PCI: hotplug: Add OCTEON PCI hotplug controller driver

This patch introduces a PCI hotplug controller driver for the OCTEON
PCIe device, a multi-function PCIe device where the first function acts
as a hotplug controller. It is equipped with MSI-x interrupts to notify
the host of hotplug events from the OCTEON firmware.

The driver facilitates the hotplugging of non-controller functions
within the same device. During probe, non-controller functions are
removed and registered as PCI hotplug slots. The slots are added back
only upon request from the device firmware. The driver also allows the
enabling and disabling of the slots via sysfs slot entries, provided by
the PCI hotplug framework.

Signed-off-by: Shijith Thotton <sthotton@marvell.com>
Signed-off-by: Vamsi Attunuru <vattunuru@marvell.com>
---

This patch introduces a PCI hotplug controller driver for OCTEON PCIe hotplug
controller. The OCTEON PCIe device is a multi-function device where the first
function acts as a PCI hotplug controller.

              +--------------------------------+
              |           Root Port            |
              +--------------------------------+
                              |
                             PCIe
                              |
+---------------------------------------------------------------+
|              OCTEON PCIe Multifunction Device                 |
+---------------------------------------------------------------+
            |                    |              |            |
            |                    |              |            |
+---------------------+  +----------------+  +-----+  +----------------+
|      Function 0     |  |   Function 1   |  | ... |  |   Function 7   |
| (Hotplug controller)|  | (Hotplug slot) |  |     |  | (Hotplug slot) |
+---------------------+  +----------------+  +-----+  +----------------+
            |
            |
+-------------------------+
|   Controller Firmware   |
+-------------------------+

The hotplug controller driver facilitates the hotplugging of non-controller
functions in the same device. During the probe of the driver, the non-controller
function are removed and registered as PCI hotplug slots. They are added back
only upon request from the device firmware. The driver also allows the user to
enable/disable the functions using sysfs slot entries provided by PCI hotplug
framework.

This solution adopts a hardware + software approach for several reasons:

1. To reduce hardware implementation cost. Supporting complete hotplug
   capability within the card would require a PCI switch implemented within.

2. In the multi-function device, non-controller functions can act as emulated
   devices. The firmware can dynamically enable or disable them at runtime.

3. Not all root ports support PCI hotplug. This approach provides greater
   flexibility and compatibility across different hardware configurations.

The hotplug controller function is lightweight and is equipped with MSI-x
interrupts to notify the host about hotplug events. Upon receiving an
interrupt, the hotplug register is read, and the required function is enabled
or disabled.

This driver will be beneficial for managing PCI hotplug events on the OCTEON
PCIe device without requiring complex hardware solutions.

 MAINTAINERS                    |   6 +
 drivers/pci/hotplug/Kconfig    |  10 +
 drivers/pci/hotplug/Makefile   |   1 +
 drivers/pci/hotplug/octep_hp.c | 351 +++++++++++++++++++++++++++++++++
 4 files changed, 368 insertions(+)
 create mode 100644 drivers/pci/hotplug/octep_hp.c

On Tue, 20 Aug 2024, Shijith Thotton wrote:

> This patch introduces a PCI hotplug controller driver for the OCTEON
> PCIe device, a multi-function PCIe device where the first function acts
> as a hotplug controller. It is equipped with MSI-x interrupts to notify
> the host of hotplug events from the OCTEON firmware.
> 
> The driver facilitates the hotplugging of non-controller functions
> within the same device. During probe, non-controller functions are
> removed and registered as PCI hotplug slots. The slots are added back
> only upon request from the device firmware. The driver also allows the
> enabling and disabling of the slots via sysfs slot entries, provided by
> the PCI hotplug framework.
> 
> Signed-off-by: Shijith Thotton <sthotton@marvell.com>
> Signed-off-by: Vamsi Attunuru <vattunuru@marvell.com>
> ---
> 
> This patch introduces a PCI hotplug controller driver for OCTEON PCIe hotplug
> controller. The OCTEON PCIe device is a multi-function device where the first
> function acts as a PCI hotplug controller.
> 
>               +--------------------------------+
>               |           Root Port            |
>               +--------------------------------+
>                               |
>                              PCIe
>                               |
> +---------------------------------------------------------------+
> |              OCTEON PCIe Multifunction Device                 |
> +---------------------------------------------------------------+
>             |                    |              |            |
>             |                    |              |            |
> +---------------------+  +----------------+  +-----+  +----------------+
> |      Function 0     |  |   Function 1   |  | ... |  |   Function 7   |
> | (Hotplug controller)|  | (Hotplug slot) |  |     |  | (Hotplug slot) |
> +---------------------+  +----------------+  +-----+  +----------------+
>             |
>             |
> +-------------------------+
> |   Controller Firmware   |
> +-------------------------+
> 
> The hotplug controller driver facilitates the hotplugging of non-controller
> functions in the same device. During the probe of the driver, the non-controller
> function are removed and registered as PCI hotplug slots. They are added back
> only upon request from the device firmware. The driver also allows the user to
> enable/disable the functions using sysfs slot entries provided by PCI hotplug
> framework.
> 
> This solution adopts a hardware + software approach for several reasons:
> 
> 1. To reduce hardware implementation cost. Supporting complete hotplug
>    capability within the card would require a PCI switch implemented within.
> 
> 2. In the multi-function device, non-controller functions can act as emulated
>    devices. The firmware can dynamically enable or disable them at runtime.
> 
> 3. Not all root ports support PCI hotplug. This approach provides greater
>    flexibility and compatibility across different hardware configurations.
> 
> The hotplug controller function is lightweight and is equipped with MSI-x
> interrupts to notify the host about hotplug events. Upon receiving an
> interrupt, the hotplug register is read, and the required function is enabled
> or disabled.
> 
> This driver will be beneficial for managing PCI hotplug events on the OCTEON
> PCIe device without requiring complex hardware solutions.
> 
>  MAINTAINERS                    |   6 +
>  drivers/pci/hotplug/Kconfig    |  10 +
>  drivers/pci/hotplug/Makefile   |   1 +
>  drivers/pci/hotplug/octep_hp.c | 351 +++++++++++++++++++++++++++++++++
>  4 files changed, 368 insertions(+)
>  create mode 100644 drivers/pci/hotplug/octep_hp.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 42decde38320..7b5a618eed1c 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -13677,6 +13677,12 @@ R:	schalla@marvell.com
>  R:	vattunuru@marvell.com
>  F:	drivers/vdpa/octeon_ep/
>  
> +MARVELL OCTEON HOTPLUG CONTROLLER DRIVER
> +R:	Shijith Thotton <sthotton@marvell.com>
> +R:	Vamsi Attunuru <vattunuru@marvell.com>
> +S:	Supported
> +F:	drivers/pci/hotplug/octep_hp.c
> +
>  MATROX FRAMEBUFFER DRIVER
>  L:	linux-fbdev@vger.kernel.org
>  S:	Orphan
> diff --git a/drivers/pci/hotplug/Kconfig b/drivers/pci/hotplug/Kconfig
> index 1472aef0fb81..2e38fd25f7ef 100644
> --- a/drivers/pci/hotplug/Kconfig
> +++ b/drivers/pci/hotplug/Kconfig
> @@ -173,4 +173,14 @@ config HOTPLUG_PCI_S390
>  
>  	  When in doubt, say Y.
>  
> +config HOTPLUG_PCI_OCTEONEP
> +	bool "OCTEON PCI device Hotplug controller driver"
> +	depends on HOTPLUG_PCI
> +	help
> +	  Say Y here if you have an OCTEON PCIe device with a hotplug
> +	  controller. This driver enables the non-controller functions of the
> +	  device to be registered as hotplug slots.
> +
> +	  When in doubt, say N.
> +
>  endif # HOTPLUG_PCI
> diff --git a/drivers/pci/hotplug/Makefile b/drivers/pci/hotplug/Makefile
> index 240c99517d5e..40aaf31fe338 100644
> --- a/drivers/pci/hotplug/Makefile
> +++ b/drivers/pci/hotplug/Makefile
> @@ -20,6 +20,7 @@ obj-$(CONFIG_HOTPLUG_PCI_RPA)		+= rpaphp.o
>  obj-$(CONFIG_HOTPLUG_PCI_RPA_DLPAR)	+= rpadlpar_io.o
>  obj-$(CONFIG_HOTPLUG_PCI_ACPI)		+= acpiphp.o
>  obj-$(CONFIG_HOTPLUG_PCI_S390)		+= s390_pci_hpc.o
> +obj-$(CONFIG_HOTPLUG_PCI_OCTEONEP)	+= octep_hp.o
>  
>  # acpiphp_ibm extends acpiphp, so should be linked afterwards.
>  
> diff --git a/drivers/pci/hotplug/octep_hp.c b/drivers/pci/hotplug/octep_hp.c
> new file mode 100644
> index 000000000000..efeb542d4993
> --- /dev/null
> +++ b/drivers/pci/hotplug/octep_hp.c
> @@ -0,0 +1,351 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright (C) 2024 Marvell. */
> +
> +#include <linux/delay.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/pci.h>
> +#include <linux/pci_hotplug.h>
> +#include <linux/slab.h>
> +
> +#define OCTEP_HP_INTR_OFFSET(x) (0x20400 + ((x) << 4))
> +#define OCTEP_HP_INTR_VECTOR(x) (16 + (x))
> +#define OCTEP_HP_DRV_NAME       "octep_hp"
> +
> +/* Interrupt vectors for hotplug enable and disable events. */
> +enum octep_hp_vec_type {
> +	OCTEP_HP_VEC_ENA,
> +	OCTEP_HP_VEC_DIS,

If I understand your code right, these cannot be arbitrary numbers but has 
to be specific numbers to match the vector number so you should explicitly 
set them to those values.

> +};
> +
> +struct octep_hp_cmd {
> +	struct list_head list;

Missing include for list_head.

> +	enum octep_hp_vec_type vec_type;
> +	u64 slot_mask;
> +};
> +
> +struct octep_hp_slot {
> +	struct list_head list;
> +	struct hotplug_slot slot;
> +	u16 slot_number;
> +	struct pci_dev *hp_pdev;
> +	unsigned int hp_devfn;
> +	struct octep_hp_controller *ctrl;
> +};
> +
> +struct octep_hp_controller {
> +	void __iomem *base;
> +	struct pci_dev *pdev;
> +	struct work_struct work;

Missing include.

> +	struct list_head slot_list;
> +	struct mutex slot_lock; /* Protects slot_list */

Missing include.

> +	struct list_head hp_cmd_list;
> +	spinlock_t hp_cmd_lock; /* Protects hp_cmd_list */
> +};
> +
> +static void octep_hp_enable_pdev(struct octep_hp_controller *hp_ctrl, struct octep_hp_slot *hp_slot)
> +{
> +	mutex_lock(&hp_ctrl->slot_lock);

Use guard().

> +	if (hp_slot->hp_pdev) {
> +		dev_dbg(&hp_slot->hp_pdev->dev, "Slot %u already enabled\n", hp_slot->slot_number);
> +		mutex_unlock(&hp_ctrl->slot_lock);
> +		return;
> +	}
> +
> +	/* Scan the device and add it to the bus */
> +	hp_slot->hp_pdev = pci_scan_single_device(hp_ctrl->pdev->bus, hp_slot->hp_devfn);
> +	pci_bus_assign_resources(hp_ctrl->pdev->bus);
> +	pci_bus_add_device(hp_slot->hp_pdev);
> +
> +	dev_dbg(&hp_slot->hp_pdev->dev, "Enabled slot %u\n", hp_slot->slot_number);

Missing include for dev_dbg().

> +	mutex_unlock(&hp_ctrl->slot_lock);
> +}
> +
> +static void octep_hp_disable_pdev(struct octep_hp_controller *hp_ctrl,
> +				  struct octep_hp_slot *hp_slot)
> +{
> +	mutex_lock(&hp_ctrl->slot_lock);

Use guard().

> +	if (!hp_slot->hp_pdev) {
> +		dev_dbg(&hp_ctrl->pdev->dev, "Slot %u already disabled\n", hp_slot->slot_number);
> +		mutex_unlock(&hp_ctrl->slot_lock);
> +		return;
> +	}
> +
> +	dev_dbg(&hp_slot->hp_pdev->dev, "Disabling slot %u\n", hp_slot->slot_number);
> +
> +	/* Remove the device from the bus */
> +	pci_stop_and_remove_bus_device_locked(hp_slot->hp_pdev);
> +	hp_slot->hp_pdev = NULL;
> +	mutex_unlock(&hp_ctrl->slot_lock);
> +}
> +
> +static int octep_hp_enable_slot(struct hotplug_slot *slot)
> +{
> +	struct octep_hp_slot *hp_slot = container_of(slot, struct octep_hp_slot, slot);

Missing include for container_of().

> +
> +	octep_hp_enable_pdev(hp_slot->ctrl, hp_slot);
> +	return 0;
> +}
> +
> +static int octep_hp_disable_slot(struct hotplug_slot *slot)
> +{
> +	struct octep_hp_slot *hp_slot = container_of(slot, struct octep_hp_slot, slot);
> +
> +	octep_hp_disable_pdev(hp_slot->ctrl, hp_slot);
> +	return 0;
> +}
> +
> +static struct hotplug_slot_ops octep_hp_slot_ops = {
> +	.enable_slot = octep_hp_enable_slot,
> +	.disable_slot = octep_hp_disable_slot,
> +};
> +
> +#define SLOT_NAME_SIZE 16
> +static int octep_hp_register_slot(struct octep_hp_controller *hp_ctrl, struct pci_dev *pdev,
> +				  u16 slot_number)
> +{
> +	char slot_name[SLOT_NAME_SIZE];
> +	struct octep_hp_slot *hp_slot;
> +	int ret;
> +
> +	hp_slot = kzalloc(sizeof(*hp_slot), GFP_KERNEL);
> +	if (!hp_slot)
> +		return -ENOMEM;
> +
> +	hp_slot->ctrl = hp_ctrl;
> +	hp_slot->hp_pdev = pdev;
> +	hp_slot->hp_devfn = pdev->devfn;
> +	hp_slot->slot_number = slot_number;
> +	hp_slot->slot.ops = &octep_hp_slot_ops;
> +
> +	snprintf(slot_name, SLOT_NAME_SIZE, "octep_hp_%u", slot_number);

SLOT_NAME_SIZE -> sizeof(slot_name)

> +	ret = pci_hp_register(&hp_slot->slot, hp_ctrl->pdev->bus, PCI_SLOT(pdev->devfn), slot_name);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to register hotplug slot %u\n", slot_number);
> +		kfree(hp_slot);
> +		return ret;
> +	}
> +
> +	octep_hp_disable_pdev(hp_ctrl, hp_slot);
> +	list_add_tail(&hp_slot->list, &hp_ctrl->slot_list);
> +
> +	return 0;
> +}
> +
> +static bool octep_hp_slot(struct octep_hp_controller *hp_ctrl, struct pci_dev *pdev)
> +{
> +	/* Check if the PCI device can be hotplugged */
> +	return pdev != hp_ctrl->pdev && pdev->bus == hp_ctrl->pdev->bus &&
> +		PCI_SLOT(pdev->devfn) == PCI_SLOT(hp_ctrl->pdev->devfn);
> +}
> +
> +static void octep_hp_cmd_handler(struct octep_hp_controller *hp_ctrl, struct octep_hp_cmd *hp_cmd)
> +{
> +	struct octep_hp_slot *hp_slot;
> +
> +	/* Enable or disable the slots based on the slot mask */
> +	list_for_each_entry(hp_slot, &hp_ctrl->slot_list, list) {
> +		if (hp_cmd->slot_mask & BIT(hp_slot->slot_number)) {

Reverse logic & use continue ?

> +			if (hp_cmd->vec_type == OCTEP_HP_VEC_ENA)
> +				octep_hp_enable_pdev(hp_ctrl, hp_slot);
> +			else
> +				octep_hp_disable_pdev(hp_ctrl, hp_slot);
> +		}
> +	}
> +}
> +
> +static void octep_hp_work_handler(struct work_struct *work)
> +{
> +	struct octep_hp_controller *hp_ctrl = container_of(work, struct octep_hp_controller, work);
> +	struct octep_hp_cmd *hp_cmd;
> +	unsigned long flags;
> +
> +	/* Process all the hotplug commands */
> +	spin_lock_irqsave(&hp_ctrl->hp_cmd_lock, flags);
> +	while (!list_empty(&hp_ctrl->hp_cmd_list)) {
> +		hp_cmd = list_first_entry(&hp_ctrl->hp_cmd_list, struct octep_hp_cmd, list);
> +		list_del(&hp_cmd->list);
> +		spin_unlock_irqrestore(&hp_ctrl->hp_cmd_lock, flags);
> +
> +		octep_hp_cmd_handler(hp_ctrl, hp_cmd);
> +		kfree(hp_cmd);
> +
> +		spin_lock_irqsave(&hp_ctrl->hp_cmd_lock, flags);
> +	}
> +	spin_unlock_irqrestore(&hp_ctrl->hp_cmd_lock, flags);
> +}
> +
> +static irqreturn_t octep_hp_intr_handler(int irq, void *data)
> +{
> +	struct octep_hp_controller *hp_ctrl = data;
> +	struct pci_dev *pdev = hp_ctrl->pdev;
> +	enum octep_hp_vec_type vec_type;
> +	struct octep_hp_cmd *hp_cmd;
> +	u64 slot_mask;
> +
> +	vec_type = pci_irq_vector(pdev, OCTEP_HP_INTR_VECTOR(OCTEP_HP_VEC_ENA)) == irq ?
> +		OCTEP_HP_VEC_ENA : OCTEP_HP_VEC_DIS;

This is a bit unusual and complicated to do all this in one statement. But 
can't you just store that ena irq number into struct octep_hp_controller 
so you don't need to make the call here every time?

> +	slot_mask = readq(hp_ctrl->base + OCTEP_HP_INTR_OFFSET(vec_type));
> +	if (!slot_mask) {
> +		dev_err(&pdev->dev, "Invalid slot mask %llx\n", slot_mask);
> +		return IRQ_HANDLED;
> +	}
> +
> +	hp_cmd = kzalloc(sizeof(*hp_cmd), GFP_ATOMIC);
> +	if (!hp_cmd)
> +		return IRQ_HANDLED;
> +
> +	hp_cmd->slot_mask = slot_mask;
> +	hp_cmd->vec_type = vec_type;
> +
> +	/* Add the command to the list and schedule the work */
> +	spin_lock(&hp_ctrl->hp_cmd_lock);
> +	list_add_tail(&hp_cmd->list, &hp_ctrl->hp_cmd_list);
> +	spin_unlock(&hp_ctrl->hp_cmd_lock);
> +	schedule_work(&hp_ctrl->work);
> +
> +	/* Clear the interrupt */
> +	writeq(slot_mask, hp_ctrl->base + OCTEP_HP_INTR_OFFSET(vec_type));
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static void octep_hp_deregister_slots(struct octep_hp_controller *hp_ctrl)
> +{
> +	struct octep_hp_slot *hp_slot, *tmp;
> +
> +	/* Deregister all the hotplug slots */
> +	list_for_each_entry_safe(hp_slot, tmp, &hp_ctrl->slot_list, list) {
> +		pci_hp_deregister(&hp_slot->slot);
> +		octep_hp_enable_pdev(hp_ctrl, hp_slot);
> +		list_del(&hp_slot->list);
> +		kfree(hp_slot);
> +	}
> +}
> +
> +static void octep_hp_controller_cleanup(void *data)
> +{
> +	struct octep_hp_controller *hp_ctrl = data;
> +
> +	pci_free_irq_vectors(hp_ctrl->pdev);
> +	flush_work(&hp_ctrl->work);
> +	octep_hp_deregister_slots(hp_ctrl);
> +}
> +
> +static int octep_hp_controller_setup(struct pci_dev *pdev, struct octep_hp_controller *hp_ctrl)
> +{
> +	struct device *dev = &pdev->dev;
> +	int ret;
> +
> +	ret = pcim_enable_device(pdev);
> +	if (ret) {
> +		dev_err(dev, "Failed to enable PCI device\n");
> +		return ret;
> +	}
> +
> +	ret = pcim_iomap_regions(pdev, BIT(0), OCTEP_HP_DRV_NAME);
> +	if (ret) {
> +		dev_err(dev, "Failed to request MMIO region\n");
> +		return ret;
> +	}
> +
> +	pci_set_master(pdev);
> +	pci_set_drvdata(pdev, hp_ctrl);
> +
> +	INIT_LIST_HEAD(&hp_ctrl->slot_list);
> +	INIT_LIST_HEAD(&hp_ctrl->hp_cmd_list);
> +	mutex_init(&hp_ctrl->slot_lock);
> +	spin_lock_init(&hp_ctrl->hp_cmd_lock);
> +	INIT_WORK(&hp_ctrl->work, octep_hp_work_handler);
> +
> +	hp_ctrl->pdev = pdev;
> +	hp_ctrl->base = pcim_iomap_table(pdev)[0];
> +	if (!hp_ctrl->base) {
> +		dev_err(dev, "Failed to get device resource map\n");
> +		return -ENODEV;
> +	}
> +
> +	ret = pci_alloc_irq_vectors(pdev, 1, OCTEP_HP_INTR_VECTOR(OCTEP_HP_VEC_DIS) + 1,
> +				    PCI_IRQ_MSIX);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to alloc MSI-X vectors");
> +		return ret;
> +	}
> +
> +	ret = devm_add_action(dev, octep_hp_controller_cleanup, hp_ctrl);
> +	if (ret) {
> +		dev_err(dev, "Failed to add action for controller cleanup\n");
> +		return ret;
> +	}
> +
> +	ret = devm_request_irq(dev, pci_irq_vector(pdev, OCTEP_HP_INTR_VECTOR(OCTEP_HP_VEC_ENA)),
> +			       octep_hp_intr_handler, 0, "octep_hp_ena", hp_ctrl);
> +	if (ret) {
> +		dev_err(dev, "Failed to register slot enable interrupt handle\n");
> +		return ret;
> +	}
> +
> +	ret = devm_request_irq(dev, pci_irq_vector(pdev, OCTEP_HP_INTR_VECTOR(OCTEP_HP_VEC_DIS)),
> +			       octep_hp_intr_handler, 0, "octep_hp_dis", hp_ctrl);
> +	if (ret) {
> +		dev_err(dev, "Failed to register slot disable interrupt handle\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int octep_hp_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> +{
> +	struct octep_hp_controller *hp_ctrl;
> +	struct pci_dev *tmp_pdev = NULL;
> +	u16 slot_number = 0;
> +	int ret;
> +
> +	hp_ctrl = devm_kzalloc(&pdev->dev, sizeof(*hp_ctrl), GFP_KERNEL);
> +	if (!hp_ctrl)
> +		return -ENOMEM;
> +
> +	ret = octep_hp_controller_setup(pdev, hp_ctrl);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to setup octep controller\n");

So both octep_hp_controller_setup() and this function print an error? 
Wouldn't the one from octep_hp_controller_setup() suffice?

>On Tue, 20 Aug 2024, Shijith Thotton wrote:
>
>> This patch introduces a PCI hotplug controller driver for the OCTEON
>> PCIe device, a multi-function PCIe device where the first function acts
>> as a hotplug controller. It is equipped with MSI-x interrupts to notify
>> the host of hotplug events from the OCTEON firmware.
>>
>> The driver facilitates the hotplugging of non-controller functions
>> within the same device. During probe, non-controller functions are
>> removed and registered as PCI hotplug slots. The slots are added back
>> only upon request from the device firmware. The driver also allows the
>> enabling and disabling of the slots via sysfs slot entries, provided by
>> the PCI hotplug framework.
>>
>> Signed-off-by: Shijith Thotton <sthotton@marvell.com>
>> Signed-off-by: Vamsi Attunuru <vattunuru@marvell.com>
>> ---
>>
>> This patch introduces a PCI hotplug controller driver for OCTEON PCIe hotplug
>> controller. The OCTEON PCIe device is a multi-function device where the first
>> function acts as a PCI hotplug controller.
>>
>>               +--------------------------------+
>>               |           Root Port            |
>>               +--------------------------------+
>>                               |
>>                              PCIe
>>                               |
>> +---------------------------------------------------------------+
>> |              OCTEON PCIe Multifunction Device                 |
>> +---------------------------------------------------------------+
>>             |                    |              |            |
>>             |                    |              |            |
>> +---------------------+  +----------------+  +-----+  +----------------+
>> |      Function 0     |  |   Function 1   |  | ... |  |   Function 7   |
>> | (Hotplug controller)|  | (Hotplug slot) |  |     |  | (Hotplug slot) |
>> +---------------------+  +----------------+  +-----+  +----------------+
>>             |
>>             |
>> +-------------------------+
>> |   Controller Firmware   |
>> +-------------------------+
>>
>> The hotplug controller driver facilitates the hotplugging of non-controller
>> functions in the same device. During the probe of the driver, the non-
>controller
>> function are removed and registered as PCI hotplug slots. They are added
>back
>> only upon request from the device firmware. The driver also allows the user
>to
>> enable/disable the functions using sysfs slot entries provided by PCI hotplug
>> framework.
>>
>> This solution adopts a hardware + software approach for several reasons:
>>
>> 1. To reduce hardware implementation cost. Supporting complete hotplug
>>    capability within the card would require a PCI switch implemented within.
>>
>> 2. In the multi-function device, non-controller functions can act as emulated
>>    devices. The firmware can dynamically enable or disable them at runtime.
>>
>> 3. Not all root ports support PCI hotplug. This approach provides greater
>>    flexibility and compatibility across different hardware configurations.
>>
>> The hotplug controller function is lightweight and is equipped with MSI-x
>> interrupts to notify the host about hotplug events. Upon receiving an
>> interrupt, the hotplug register is read, and the required function is enabled
>> or disabled.
>>
>> This driver will be beneficial for managing PCI hotplug events on the OCTEON
>> PCIe device without requiring complex hardware solutions.
>>
>>  MAINTAINERS                    |   6 +
>>  drivers/pci/hotplug/Kconfig    |  10 +
>>  drivers/pci/hotplug/Makefile   |   1 +
>>  drivers/pci/hotplug/octep_hp.c | 351
>+++++++++++++++++++++++++++++++++
>>  4 files changed, 368 insertions(+)
>>  create mode 100644 drivers/pci/hotplug/octep_hp.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 42decde38320..7b5a618eed1c 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -13677,6 +13677,12 @@ R:	schalla@marvell.com
>>  R:	vattunuru@marvell.com
>>  F:	drivers/vdpa/octeon_ep/
>>
>> +MARVELL OCTEON HOTPLUG CONTROLLER DRIVER
>> +R:	Shijith Thotton <sthotton@marvell.com>
>> +R:	Vamsi Attunuru <vattunuru@marvell.com>
>> +S:	Supported
>> +F:	drivers/pci/hotplug/octep_hp.c
>> +
>>  MATROX FRAMEBUFFER DRIVER
>>  L:	linux-fbdev@vger.kernel.org
>>  S:	Orphan
>> diff --git a/drivers/pci/hotplug/Kconfig b/drivers/pci/hotplug/Kconfig
>> index 1472aef0fb81..2e38fd25f7ef 100644
>> --- a/drivers/pci/hotplug/Kconfig
>> +++ b/drivers/pci/hotplug/Kconfig
>> @@ -173,4 +173,14 @@ config HOTPLUG_PCI_S390
>>
>>  	  When in doubt, say Y.
>>
>> +config HOTPLUG_PCI_OCTEONEP
>> +	bool "OCTEON PCI device Hotplug controller driver"
>> +	depends on HOTPLUG_PCI
>> +	help
>> +	  Say Y here if you have an OCTEON PCIe device with a hotplug
>> +	  controller. This driver enables the non-controller functions of the
>> +	  device to be registered as hotplug slots.
>> +
>> +	  When in doubt, say N.
>> +
>>  endif # HOTPLUG_PCI
>> diff --git a/drivers/pci/hotplug/Makefile b/drivers/pci/hotplug/Makefile
>> index 240c99517d5e..40aaf31fe338 100644
>> --- a/drivers/pci/hotplug/Makefile
>> +++ b/drivers/pci/hotplug/Makefile
>> @@ -20,6 +20,7 @@ obj-$(CONFIG_HOTPLUG_PCI_RPA)		+=
>rpaphp.o
>>  obj-$(CONFIG_HOTPLUG_PCI_RPA_DLPAR)	+= rpadlpar_io.o
>>  obj-$(CONFIG_HOTPLUG_PCI_ACPI)		+= acpiphp.o
>>  obj-$(CONFIG_HOTPLUG_PCI_S390)		+= s390_pci_hpc.o
>> +obj-$(CONFIG_HOTPLUG_PCI_OCTEONEP)	+= octep_hp.o
>>
>>  # acpiphp_ibm extends acpiphp, so should be linked afterwards.
>>
>> diff --git a/drivers/pci/hotplug/octep_hp.c b/drivers/pci/hotplug/octep_hp.c
>> new file mode 100644
>> index 000000000000..efeb542d4993
>> --- /dev/null
>> +++ b/drivers/pci/hotplug/octep_hp.c
>> @@ -0,0 +1,351 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/* Copyright (C) 2024 Marvell. */
>> +
>> +#include <linux/delay.h>
>> +#include <linux/init.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/pci.h>
>> +#include <linux/pci_hotplug.h>
>> +#include <linux/slab.h>
>> +
>> +#define OCTEP_HP_INTR_OFFSET(x) (0x20400 + ((x) << 4))
>> +#define OCTEP_HP_INTR_VECTOR(x) (16 + (x))
>> +#define OCTEP_HP_DRV_NAME       "octep_hp"
>> +
>> +/* Interrupt vectors for hotplug enable and disable events. */
>> +enum octep_hp_vec_type {
>> +	OCTEP_HP_VEC_ENA,
>> +	OCTEP_HP_VEC_DIS,
>
>If I understand your code right, these cannot be arbitrary numbers but has
>to be specific numbers to match the vector number so you should explicitly
>set them to those values.

octep_hp_vec_type is used to specify the type of hotplug interrupt. There are
two types of hotplug interrupts, enable and disable. The vectors for these
interrupts are formed using the macros OCTEP_HP_INTR_VECTOR(x) where x is the
type of interrupt. The vectors for enable and disable interrupts are 16 and 17
respectively.

I have not set them in enum since the vectors are sequential. I will change it as
below to make it clearer.

enum octep_hp_intr_type {
        OCTEP_HP_INTR_INVALID = -1,
        OCTEP_HP_INTR_ENA = 0,
        OCTEP_HP_INTR_DIS = 1,
};

>> +};
>> +
>> +struct octep_hp_cmd {
>> +	struct list_head list;
>
>Missing include for list_head.

Will add.

>
>> +	enum octep_hp_vec_type vec_type;
>> +	u64 slot_mask;
>> +};
>> +
>> +struct octep_hp_slot {
>> +	struct list_head list;
>> +	struct hotplug_slot slot;
>> +	u16 slot_number;
>> +	struct pci_dev *hp_pdev;
>> +	unsigned int hp_devfn;
>> +	struct octep_hp_controller *ctrl;
>> +};
>> +
>> +struct octep_hp_controller {
>> +	void __iomem *base;
>> +	struct pci_dev *pdev;
>> +	struct work_struct work;
>
>Missing include.

Will add.

>
>> +	struct list_head slot_list;
>> +	struct mutex slot_lock; /* Protects slot_list */
>
>Missing include.

Will add.

>
>> +	struct list_head hp_cmd_list;
>> +	spinlock_t hp_cmd_lock; /* Protects hp_cmd_list */
>> +};
>> +
>> +static void octep_hp_enable_pdev(struct octep_hp_controller *hp_ctrl,
>struct octep_hp_slot *hp_slot)
>> +{
>> +	mutex_lock(&hp_ctrl->slot_lock);
>
>Use guard().

Will change to use guard().

>
>> +	if (hp_slot->hp_pdev) {
>> +		dev_dbg(&hp_slot->hp_pdev->dev, "Slot %u already
>enabled\n", hp_slot->slot_number);
>> +		mutex_unlock(&hp_ctrl->slot_lock);
>> +		return;
>> +	}
>> +
>> +	/* Scan the device and add it to the bus */
>> +	hp_slot->hp_pdev = pci_scan_single_device(hp_ctrl->pdev->bus,
>hp_slot->hp_devfn);
>> +	pci_bus_assign_resources(hp_ctrl->pdev->bus);
>> +	pci_bus_add_device(hp_slot->hp_pdev);
>> +
>> +	dev_dbg(&hp_slot->hp_pdev->dev, "Enabled slot %u\n", hp_slot-
>>slot_number);
>
>Missing include for dev_dbg().
>

Will add.

>> +	mutex_unlock(&hp_ctrl->slot_lock);
>> +}
>> +
>> +static void octep_hp_disable_pdev(struct octep_hp_controller *hp_ctrl,
>> +				  struct octep_hp_slot *hp_slot)
>> +{
>> +	mutex_lock(&hp_ctrl->slot_lock);
>
>Use guard().

Will change.

>
>> +	if (!hp_slot->hp_pdev) {
>> +		dev_dbg(&hp_ctrl->pdev->dev, "Slot %u already disabled\n",
>hp_slot->slot_number);
>> +		mutex_unlock(&hp_ctrl->slot_lock);
>> +		return;
>> +	}
>> +
>> +	dev_dbg(&hp_slot->hp_pdev->dev, "Disabling slot %u\n", hp_slot-
>>slot_number);
>> +
>> +	/* Remove the device from the bus */
>> +	pci_stop_and_remove_bus_device_locked(hp_slot->hp_pdev);
>> +	hp_slot->hp_pdev = NULL;
>> +	mutex_unlock(&hp_ctrl->slot_lock);
>> +}
>> +
>> +static int octep_hp_enable_slot(struct hotplug_slot *slot)
>> +{
>> +	struct octep_hp_slot *hp_slot = container_of(slot, struct
>octep_hp_slot, slot);
>
>Missing include for container_of().

Will add.

>
>> +
>> +	octep_hp_enable_pdev(hp_slot->ctrl, hp_slot);
>> +	return 0;
>> +}
>> +
>> +static int octep_hp_disable_slot(struct hotplug_slot *slot)
>> +{
>> +	struct octep_hp_slot *hp_slot = container_of(slot, struct
>octep_hp_slot, slot);
>> +
>> +	octep_hp_disable_pdev(hp_slot->ctrl, hp_slot);
>> +	return 0;
>> +}
>> +
>> +static struct hotplug_slot_ops octep_hp_slot_ops = {
>> +	.enable_slot = octep_hp_enable_slot,
>> +	.disable_slot = octep_hp_disable_slot,
>> +};
>> +
>> +#define SLOT_NAME_SIZE 16
>> +static int octep_hp_register_slot(struct octep_hp_controller *hp_ctrl, struct
>pci_dev *pdev,
>> +				  u16 slot_number)
>> +{
>> +	char slot_name[SLOT_NAME_SIZE];
>> +	struct octep_hp_slot *hp_slot;
>> +	int ret;
>> +
>> +	hp_slot = kzalloc(sizeof(*hp_slot), GFP_KERNEL);
>> +	if (!hp_slot)
>> +		return -ENOMEM;
>> +
>> +	hp_slot->ctrl = hp_ctrl;
>> +	hp_slot->hp_pdev = pdev;
>> +	hp_slot->hp_devfn = pdev->devfn;
>> +	hp_slot->slot_number = slot_number;
>> +	hp_slot->slot.ops = &octep_hp_slot_ops;
>> +
>> +	snprintf(slot_name, SLOT_NAME_SIZE, "octep_hp_%u", slot_number);
>
>SLOT_NAME_SIZE -> sizeof(slot_name)

Will change.

>
>> +	ret = pci_hp_register(&hp_slot->slot, hp_ctrl->pdev->bus,
>PCI_SLOT(pdev->devfn), slot_name);
>> +	if (ret) {
>> +		dev_err(&pdev->dev, "Failed to register hotplug slot %u\n",
>slot_number);
>> +		kfree(hp_slot);
>> +		return ret;
>> +	}
>> +
>> +	octep_hp_disable_pdev(hp_ctrl, hp_slot);
>> +	list_add_tail(&hp_slot->list, &hp_ctrl->slot_list);
>> +
>> +	return 0;
>> +}
>> +
>> +static bool octep_hp_slot(struct octep_hp_controller *hp_ctrl, struct pci_dev
>*pdev)
>> +{
>> +	/* Check if the PCI device can be hotplugged */
>> +	return pdev != hp_ctrl->pdev && pdev->bus == hp_ctrl->pdev->bus &&
>> +		PCI_SLOT(pdev->devfn) == PCI_SLOT(hp_ctrl->pdev->devfn);
>> +}
>> +
>> +static void octep_hp_cmd_handler(struct octep_hp_controller *hp_ctrl,
>struct octep_hp_cmd *hp_cmd)
>> +{
>> +	struct octep_hp_slot *hp_slot;
>> +
>> +	/* Enable or disable the slots based on the slot mask */
>> +	list_for_each_entry(hp_slot, &hp_ctrl->slot_list, list) {
>> +		if (hp_cmd->slot_mask & BIT(hp_slot->slot_number)) {
>
>Reverse logic & use continue ?

Sure. Will change.

>
>> +			if (hp_cmd->vec_type == OCTEP_HP_VEC_ENA)
>> +				octep_hp_enable_pdev(hp_ctrl, hp_slot);
>> +			else
>> +				octep_hp_disable_pdev(hp_ctrl, hp_slot);
>> +		}
>> +	}
>> +}
>> +
>> +static void octep_hp_work_handler(struct work_struct *work)
>> +{
>> +	struct octep_hp_controller *hp_ctrl = container_of(work, struct
>octep_hp_controller, work);
>> +	struct octep_hp_cmd *hp_cmd;
>> +	unsigned long flags;
>> +
>> +	/* Process all the hotplug commands */
>> +	spin_lock_irqsave(&hp_ctrl->hp_cmd_lock, flags);
>> +	while (!list_empty(&hp_ctrl->hp_cmd_list)) {
>> +		hp_cmd = list_first_entry(&hp_ctrl->hp_cmd_list, struct
>octep_hp_cmd, list);
>> +		list_del(&hp_cmd->list);
>> +		spin_unlock_irqrestore(&hp_ctrl->hp_cmd_lock, flags);
>> +
>> +		octep_hp_cmd_handler(hp_ctrl, hp_cmd);
>> +		kfree(hp_cmd);
>> +
>> +		spin_lock_irqsave(&hp_ctrl->hp_cmd_lock, flags);
>> +	}
>> +	spin_unlock_irqrestore(&hp_ctrl->hp_cmd_lock, flags);
>> +}
>> +
>> +static irqreturn_t octep_hp_intr_handler(int irq, void *data)
>> +{
>> +	struct octep_hp_controller *hp_ctrl = data;
>> +	struct pci_dev *pdev = hp_ctrl->pdev;
>> +	enum octep_hp_vec_type vec_type;
>> +	struct octep_hp_cmd *hp_cmd;
>> +	u64 slot_mask;
>> +
>> +	vec_type = pci_irq_vector(pdev,
>OCTEP_HP_INTR_VECTOR(OCTEP_HP_VEC_ENA)) == irq ?
>> +		OCTEP_HP_VEC_ENA : OCTEP_HP_VEC_DIS;
>
>This is a bit unusual and complicated to do all this in one statement. But
>can't you just store that ena irq number into struct octep_hp_controller
>so you don't need to make the call here every time?
>

Will move this logic to a new function to get the vector type based on the irq
number. Avoided storing the irq number in the controller structure as we don't
expect a lot of hotplug interrupts.

>> +	slot_mask = readq(hp_ctrl->base +
>OCTEP_HP_INTR_OFFSET(vec_type));
>> +	if (!slot_mask) {
>> +		dev_err(&pdev->dev, "Invalid slot mask %llx\n", slot_mask);
>> +		return IRQ_HANDLED;
>> +	}
>> +
>> +	hp_cmd = kzalloc(sizeof(*hp_cmd), GFP_ATOMIC);
>> +	if (!hp_cmd)
>> +		return IRQ_HANDLED;
>> +
>> +	hp_cmd->slot_mask = slot_mask;
>> +	hp_cmd->vec_type = vec_type;
>> +
>> +	/* Add the command to the list and schedule the work */
>> +	spin_lock(&hp_ctrl->hp_cmd_lock);
>> +	list_add_tail(&hp_cmd->list, &hp_ctrl->hp_cmd_list);
>> +	spin_unlock(&hp_ctrl->hp_cmd_lock);
>> +	schedule_work(&hp_ctrl->work);
>> +
>> +	/* Clear the interrupt */
>> +	writeq(slot_mask, hp_ctrl->base +
>OCTEP_HP_INTR_OFFSET(vec_type));
>> +
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +static void octep_hp_deregister_slots(struct octep_hp_controller *hp_ctrl)
>> +{
>> +	struct octep_hp_slot *hp_slot, *tmp;
>> +
>> +	/* Deregister all the hotplug slots */
>> +	list_for_each_entry_safe(hp_slot, tmp, &hp_ctrl->slot_list, list) {
>> +		pci_hp_deregister(&hp_slot->slot);
>> +		octep_hp_enable_pdev(hp_ctrl, hp_slot);
>> +		list_del(&hp_slot->list);
>> +		kfree(hp_slot);
>> +	}
>> +}
>> +
>> +static void octep_hp_controller_cleanup(void *data)
>> +{
>> +	struct octep_hp_controller *hp_ctrl = data;
>> +
>> +	pci_free_irq_vectors(hp_ctrl->pdev);
>> +	flush_work(&hp_ctrl->work);
>> +	octep_hp_deregister_slots(hp_ctrl);
>> +}
>> +
>> +static int octep_hp_controller_setup(struct pci_dev *pdev, struct
>octep_hp_controller *hp_ctrl)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	int ret;
>> +
>> +	ret = pcim_enable_device(pdev);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to enable PCI device\n");
>> +		return ret;
>> +	}
>> +
>> +	ret = pcim_iomap_regions(pdev, BIT(0), OCTEP_HP_DRV_NAME);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to request MMIO region\n");
>> +		return ret;
>> +	}
>> +
>> +	pci_set_master(pdev);
>> +	pci_set_drvdata(pdev, hp_ctrl);
>> +
>> +	INIT_LIST_HEAD(&hp_ctrl->slot_list);
>> +	INIT_LIST_HEAD(&hp_ctrl->hp_cmd_list);
>> +	mutex_init(&hp_ctrl->slot_lock);
>> +	spin_lock_init(&hp_ctrl->hp_cmd_lock);
>> +	INIT_WORK(&hp_ctrl->work, octep_hp_work_handler);
>> +
>> +	hp_ctrl->pdev = pdev;
>> +	hp_ctrl->base = pcim_iomap_table(pdev)[0];
>> +	if (!hp_ctrl->base) {
>> +		dev_err(dev, "Failed to get device resource map\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	ret = pci_alloc_irq_vectors(pdev, 1,
>OCTEP_HP_INTR_VECTOR(OCTEP_HP_VEC_DIS) + 1,
>> +				    PCI_IRQ_MSIX);
>> +	if (ret < 0) {
>> +		dev_err(dev, "Failed to alloc MSI-X vectors");
>> +		return ret;
>> +	}
>> +
>> +	ret = devm_add_action(dev, octep_hp_controller_cleanup, hp_ctrl);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to add action for controller cleanup\n");
>> +		return ret;
>> +	}
>> +
>> +	ret = devm_request_irq(dev, pci_irq_vector(pdev,
>OCTEP_HP_INTR_VECTOR(OCTEP_HP_VEC_ENA)),
>> +			       octep_hp_intr_handler, 0, "octep_hp_ena",
>hp_ctrl);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to register slot enable interrupt
>handle\n");
>> +		return ret;
>> +	}
>> +
>> +	ret = devm_request_irq(dev, pci_irq_vector(pdev,
>OCTEP_HP_INTR_VECTOR(OCTEP_HP_VEC_DIS)),
>> +			       octep_hp_intr_handler, 0, "octep_hp_dis", hp_ctrl);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to register slot disable interrupt
>handle\n");
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int octep_hp_pci_probe(struct pci_dev *pdev, const struct
>pci_device_id *id)
>> +{
>> +	struct octep_hp_controller *hp_ctrl;
>> +	struct pci_dev *tmp_pdev = NULL;
>> +	u16 slot_number = 0;
>> +	int ret;
>> +
>> +	hp_ctrl = devm_kzalloc(&pdev->dev, sizeof(*hp_ctrl), GFP_KERNEL);
>> +	if (!hp_ctrl)
>> +		return -ENOMEM;
>> +
>> +	ret = octep_hp_controller_setup(pdev, hp_ctrl);
>> +	if (ret) {
>> +		dev_err(&pdev->dev, "Failed to setup octep controller\n");
>
>So both octep_hp_controller_setup() and this function print an error?
>Wouldn't the one from octep_hp_controller_setup() suffice?

Will remove the extra print.

>--
> i.
>
>> +		return ret;
>> +	}
>> +
>> +	/*
>> +	 * Register all hotplug slots. Hotplug controller is the first function of
>the PCI device.
>> +	 * The hotplug slots are the remaining functions of the PCI device. They
>are removed from
>> +	 * the bus and are added back when the hotplug event is triggered.
>
>Reflow the comment to 80 chars.

Will change.

>
>> +	 */
>> +	for_each_pci_dev(tmp_pdev) {
>> +		if (octep_hp_slot(hp_ctrl, tmp_pdev)) {
>
>Reverse logic & use continue.
>

Will change.

>> +			ret = octep_hp_register_slot(hp_ctrl, tmp_pdev,
>slot_number++);
>> +			if (ret) {
>> +				dev_err(&pdev->dev, "Failed to register
>hotplug slots.\n");
>> +				return ret;
>> +			}
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +#define OCTEP_DEVID_HP_CONTROLLER 0xa0e3
>> +static struct pci_device_id octep_hp_pci_map[] = {
>> +	{ PCI_DEVICE(PCI_VENDOR_ID_CAVIUM,
>OCTEP_DEVID_HP_CONTROLLER) },
>> +	{ 0 },
>> +};
>> +
>> +static struct pci_driver octep_hp = {
>> +	.name     = OCTEP_HP_DRV_NAME,
>> +	.id_table = octep_hp_pci_map,
>> +	.probe    = octep_hp_pci_probe,
>> +};
>> +
>> +module_pci_driver(octep_hp);
>> +
>> +MODULE_LICENSE("GPL");
>> +MODULE_AUTHOR("Marvell");
>> +MODULE_DESCRIPTION("OCTEON PCIe device hotplug controller driver");
>>

Thanks for the review.
Shijith

On Tue, 20 Aug 2024 20:57:20 +0530
Shijith Thotton <sthotton@marvell.com> wrote:

> This patch introduces a PCI hotplug controller driver for the OCTEON
> PCIe device, a multi-function PCIe device where the first function acts
> as a hotplug controller. It is equipped with MSI-x interrupts to notify
> the host of hotplug events from the OCTEON firmware.
> 
> The driver facilitates the hotplugging of non-controller functions
> within the same device. During probe, non-controller functions are
> removed and registered as PCI hotplug slots. The slots are added back
> only upon request from the device firmware. The driver also allows the
> enabling and disabling of the slots via sysfs slot entries, provided by
> the PCI hotplug framework.
> 
> Signed-off-by: Shijith Thotton <sthotton@marvell.com>
> Signed-off-by: Vamsi Attunuru <vattunuru@marvell.com>
I was curious, so drive by review.

What was Vamsi's involvement?  Given Shijith sent this
I'd guess co developer?  In which Co-developed-by tag
should be used.

Various random comments on things inline.

> ---
> 
> This patch introduces a PCI hotplug controller driver for OCTEON PCIe hotplug
> controller. The OCTEON PCIe device is a multi-function device where the first
> function acts as a PCI hotplug controller.
> 
>               +--------------------------------+
>               |           Root Port            |
>               +--------------------------------+
>                               |
>                              PCIe
>                               |
> +---------------------------------------------------------------+
> |              OCTEON PCIe Multifunction Device                 |
> +---------------------------------------------------------------+
>             |                    |              |            |
>             |                    |              |            |
> +---------------------+  +----------------+  +-----+  +----------------+
> |      Function 0     |  |   Function 1   |  | ... |  |   Function 7   |
> | (Hotplug controller)|  | (Hotplug slot) |  |     |  | (Hotplug slot) |
> +---------------------+  +----------------+  +-----+  +----------------+
>             |
>             |
> +-------------------------+
> |   Controller Firmware   |
> +-------------------------+
> 
> The hotplug controller driver facilitates the hotplugging of non-controller
> functions in the same device. During the probe of the driver, the non-controller
> function are removed and registered as PCI hotplug slots. They are added back
> only upon request from the device firmware. The driver also allows the user to
> enable/disable the functions using sysfs slot entries provided by PCI hotplug
> framework.
> 
> This solution adopts a hardware + software approach for several reasons:
> 
> 1. To reduce hardware implementation cost. Supporting complete hotplug
>    capability within the card would require a PCI switch implemented within.
> 
> 2. In the multi-function device, non-controller functions can act as emulated
>    devices. The firmware can dynamically enable or disable them at runtime.
> 
> 3. Not all root ports support PCI hotplug. This approach provides greater
>    flexibility and compatibility across different hardware configurations.
> 
> The hotplug controller function is lightweight and is equipped with MSI-x
> interrupts to notify the host about hotplug events. Upon receiving an
> interrupt, the hotplug register is read, and the required function is enabled
> or disabled.
> 
> This driver will be beneficial for managing PCI hotplug events on the OCTEON
> PCIe device without requiring complex hardware solutions.
> 
>  MAINTAINERS                    |   6 +
>  drivers/pci/hotplug/Kconfig    |  10 +
>  drivers/pci/hotplug/Makefile   |   1 +
>  drivers/pci/hotplug/octep_hp.c | 351 +++++++++++++++++++++++++++++++++
>  4 files changed, 368 insertions(+)
>  create mode 100644 drivers/pci/hotplug/octep_hp.c
> 


> diff --git a/drivers/pci/hotplug/octep_hp.c b/drivers/pci/hotplug/octep_hp.c
> new file mode 100644
> index 000000000000..efeb542d4993
> --- /dev/null
> +++ b/drivers/pci/hotplug/octep_hp.c
> @@ -0,0 +1,351 @@

> +struct octep_hp_controller {
> +	void __iomem *base;
> +	struct pci_dev *pdev;
> +	struct work_struct work;
> +	struct list_head slot_list;
> +	struct mutex slot_lock; /* Protects slot_list */
> +	struct list_head hp_cmd_list;
> +	spinlock_t hp_cmd_lock; /* Protects hp_cmd_list */
> +};

> +static void octep_hp_disable_pdev(struct octep_hp_controller *hp_ctrl,
> +				  struct octep_hp_slot *hp_slot)
> +{
> +	mutex_lock(&hp_ctrl->slot_lock);

guard(mutex)(&hp_ctrl->slot_lock);

Same for other simple cases where we can avoid explicit unlock in error paths
+ main path.


> +	if (!hp_slot->hp_pdev) {
> +		dev_dbg(&hp_ctrl->pdev->dev, "Slot %u already disabled\n", hp_slot->slot_number);
> +		mutex_unlock(&hp_ctrl->slot_lock);
> +		return;
> +	}
> +
> +	dev_dbg(&hp_slot->hp_pdev->dev, "Disabling slot %u\n", hp_slot->slot_number);
> +
> +	/* Remove the device from the bus */
> +	pci_stop_and_remove_bus_device_locked(hp_slot->hp_pdev);
> +	hp_slot->hp_pdev = NULL;
> +	mutex_unlock(&hp_ctrl->slot_lock);
> +}

> +#define SLOT_NAME_SIZE 16
> +static int octep_hp_register_slot(struct octep_hp_controller *hp_ctrl, struct pci_dev *pdev,
> +				  u16 slot_number)
> +{
> +	char slot_name[SLOT_NAME_SIZE];
> +	struct octep_hp_slot *hp_slot;
> +	int ret;
> +
> +	hp_slot = kzalloc(sizeof(*hp_slot), GFP_KERNEL);
> +	if (!hp_slot)
> +		return -ENOMEM;
> +
> +	hp_slot->ctrl = hp_ctrl;
> +	hp_slot->hp_pdev = pdev;
> +	hp_slot->hp_devfn = pdev->devfn;
> +	hp_slot->slot_number = slot_number;
> +	hp_slot->slot.ops = &octep_hp_slot_ops;
> +
> +	snprintf(slot_name, SLOT_NAME_SIZE, "octep_hp_%u", slot_number);
> +	ret = pci_hp_register(&hp_slot->slot, hp_ctrl->pdev->bus, PCI_SLOT(pdev->devfn), slot_name);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to register hotplug slot %u\n", slot_number);
> +		kfree(hp_slot);
> +		return ret;
		return dev_err_probe() in here as well.

> +	}
> +
> +	octep_hp_disable_pdev(hp_ctrl, hp_slot);
> +	list_add_tail(&hp_slot->list, &hp_ctrl->slot_list);
> +
> +	return 0;
> +}
> +
> +static bool octep_hp_slot(struct octep_hp_controller *hp_ctrl, struct pci_dev *pdev)
> +{
> +	/* Check if the PCI device can be hotplugged */
> +	return pdev != hp_ctrl->pdev && pdev->bus == hp_ctrl->pdev->bus &&
> +		PCI_SLOT(pdev->devfn) == PCI_SLOT(hp_ctrl->pdev->devfn);
> +}
> +
> +static void octep_hp_cmd_handler(struct octep_hp_controller *hp_ctrl, struct octep_hp_cmd *hp_cmd)

Line break as that's getting long for little reason.

> +{
> +	struct octep_hp_slot *hp_slot;
> +
> +	/* Enable or disable the slots based on the slot mask */
> +	list_for_each_entry(hp_slot, &hp_ctrl->slot_list, list) {
> +		if (hp_cmd->slot_mask & BIT(hp_slot->slot_number)) {
> +			if (hp_cmd->vec_type == OCTEP_HP_VEC_ENA)
> +				octep_hp_enable_pdev(hp_ctrl, hp_slot);
> +			else
> +				octep_hp_disable_pdev(hp_ctrl, hp_slot);
> +		}
> +	}
> +}
> +
> +static void octep_hp_work_handler(struct work_struct *work)
> +{
> +	struct octep_hp_controller *hp_ctrl = container_of(work, struct octep_hp_controller, work);

Add a line break.

> +	struct octep_hp_cmd *hp_cmd;
> +	unsigned long flags;

...

> +
> +static void octep_hp_deregister_slots(struct octep_hp_controller *hp_ctrl)
> +{
> +	struct octep_hp_slot *hp_slot, *tmp;
> +
> +	/* Deregister all the hotplug slots */
> +	list_for_each_entry_safe(hp_slot, tmp, &hp_ctrl->slot_list, list) {
> +		pci_hp_deregister(&hp_slot->slot);
> +		octep_hp_enable_pdev(hp_ctrl, hp_slot);
> +		list_del(&hp_slot->list);
> +		kfree(hp_slot);

As below, maybe just register cleanup for one slot at a time.
That will need a bit of magic to get form the slot to the hp_ctrl though.

Plus point is simpler logic to follow.


> +	}
> +}
> +
> +static void octep_hp_controller_cleanup(void *data)
> +{
> +	struct octep_hp_controller *hp_ctrl = data;
> +
> +	pci_free_irq_vectors(hp_ctrl->pdev);
> +	flush_work(&hp_ctrl->work);
I'd prefer to see this broken up so we have
simple steps.
1. Add action 1 in probe.
2. Add cleanup for action 1 in probe
3. Add action 2 in probe etc.

Otherwise it can be a bit tricky to review.

> +	octep_hp_deregister_slots(hp_ctrl);

This is particular is no where near the place where the
slots are registered.
May be better to register one cleanup function call
per slot as then it will also be nice and simple to follow.


> +}
> +
> +static int octep_hp_controller_setup(struct pci_dev *pdev, struct octep_hp_controller *hp_ctrl)
> +{
> +	struct device *dev = &pdev->dev;
> +	int ret;
> +
> +	ret = pcim_enable_device(pdev);
> +	if (ret) {
> +		dev_err(dev, "Failed to enable PCI device\n");
Only called from probe, so
		return dev_err_probe()

> +		return ret;
> +	}
> +
> +	ret = pcim_iomap_regions(pdev, BIT(0), OCTEP_HP_DRV_NAME);
Given there is a patch on list deprecating this, reconsider.
https://lore.kernel.org/all/20240807083018.8734-2-pstanner@redhat.com/
+CC Philipp


> +	if (ret) {
> +		dev_err(dev, "Failed to request MMIO region\n");
> +		return ret;

Same thing on return dev_err_probe here and later.

> +	}
> +
> +	pci_set_master(pdev);
> +	pci_set_drvdata(pdev, hp_ctrl);
> +
> +	INIT_LIST_HEAD(&hp_ctrl->slot_list);
> +	INIT_LIST_HEAD(&hp_ctrl->hp_cmd_list);
> +	mutex_init(&hp_ctrl->slot_lock);
> +	spin_lock_init(&hp_ctrl->hp_cmd_lock);
> +	INIT_WORK(&hp_ctrl->work, octep_hp_work_handler);
> +
> +	hp_ctrl->pdev = pdev;
> +	hp_ctrl->base = pcim_iomap_table(pdev)[0];
> +	if (!hp_ctrl->base) {
> +		dev_err(dev, "Failed to get device resource map\n");
> +		return -ENODEV;
> +	}
> +
> +	ret = pci_alloc_irq_vectors(pdev, 1, OCTEP_HP_INTR_VECTOR(OCTEP_HP_VEC_DIS) + 1,
> +				    PCI_IRQ_MSIX);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to alloc MSI-X vectors");
> +		return ret;
> +	}
> +
> +	ret = devm_add_action(dev, octep_hp_controller_cleanup, hp_ctrl);
> +	if (ret) {
> +		dev_err(dev, "Failed to add action for controller cleanup\n");
> +		return ret;
> +	}
> +
> +	ret = devm_request_irq(dev, pci_irq_vector(pdev, OCTEP_HP_INTR_VECTOR(OCTEP_HP_VEC_ENA)),
> +			       octep_hp_intr_handler, 0, "octep_hp_ena", hp_ctrl);
> +	if (ret) {
> +		dev_err(dev, "Failed to register slot enable interrupt handle\n");
> +		return ret;
> +	}
> +
> +	ret = devm_request_irq(dev, pci_irq_vector(pdev, OCTEP_HP_INTR_VECTOR(OCTEP_HP_VEC_DIS)),
> +			       octep_hp_intr_handler, 0, "octep_hp_dis", hp_ctrl);
> +	if (ret) {
> +		dev_err(dev, "Failed to register slot disable interrupt handle\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int octep_hp_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> +{
> +	struct octep_hp_controller *hp_ctrl;
> +	struct pci_dev *tmp_pdev = NULL;
> +	u16 slot_number = 0;
> +	int ret;
> +
> +	hp_ctrl = devm_kzalloc(&pdev->dev, sizeof(*hp_ctrl), GFP_KERNEL);
> +	if (!hp_ctrl)
> +		return -ENOMEM;
> +
> +	ret = octep_hp_controller_setup(pdev, hp_ctrl);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to setup octep controller\n");
> +		return ret;
return dev_err_probe()
actually no. Drop it. There are more informative error prints for all the
conditions. We probably don't care that the end result is this specific
function fails (more than an irq request failed etc).


> +	}
> +
> +	/*
> +	 * Register all hotplug slots. Hotplug controller is the first function of the PCI device.
> +	 * The hotplug slots are the remaining functions of the PCI device. They are removed from
> +	 * the bus and are added back when the hotplug event is triggered.
> +	 */
> +	for_each_pci_dev(tmp_pdev) {
> +		if (octep_hp_slot(hp_ctrl, tmp_pdev)) {
What IIpo said on this.  No one likes deep indent ;)
> +			ret = octep_hp_register_slot(hp_ctrl, tmp_pdev, slot_number++);
> +			if (ret) {
> +				dev_err(&pdev->dev, "Failed to register hotplug slots.\n");
> +				return ret;

return dev_err_probe();

Cleaner in general even if no chance of deferral.



> +			}
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +#define OCTEP_DEVID_HP_CONTROLLER 0xa0e3
> +static struct pci_device_id octep_hp_pci_map[] = {
> +	{ PCI_DEVICE(PCI_VENDOR_ID_CAVIUM, OCTEP_DEVID_HP_CONTROLLER) },
> +	{ 0 },

{ }
Is sufficient. I can't remember if that's common style in PCI or not though.

> +};

Hi Shijith,

kernel test robot noticed the following build errors:

[auto build test ERROR on pci/next]
[also build test ERROR on pci/for-linus linus/master v6.11-rc4 next-20240821]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Shijith-Thotton/PCI-hotplug-Add-OCTEON-PCI-hotplug-controller-driver/20240820-233005
base:   https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git next
patch link:    https://lore.kernel.org/r/20240820152734.642533-1-sthotton%40marvell.com
patch subject: [PATCH] PCI: hotplug: Add OCTEON PCI hotplug controller driver
config: mips-allyesconfig (https://download.01.org/0day-ci/archive/20240821/202408212127.ed49pQkJ-lkp@intel.com/config)
compiler: mips-linux-gcc (GCC) 14.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240821/202408212127.ed49pQkJ-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202408212127.ed49pQkJ-lkp@intel.com/

All errors (new ones prefixed by >>):

   drivers/pci/hotplug/octep_hp.c: In function 'octep_hp_intr_handler':
>> drivers/pci/hotplug/octep_hp.c:190:21: error: implicit declaration of function 'readq'; did you mean 'readl'? [-Wimplicit-function-declaration]
     190 |         slot_mask = readq(hp_ctrl->base + OCTEP_HP_INTR_OFFSET(vec_type));
         |                     ^~~~~
         |                     readl
>> drivers/pci/hotplug/octep_hp.c:210:9: error: implicit declaration of function 'writeq'; did you mean 'writel'? [-Wimplicit-function-declaration]
     210 |         writeq(slot_mask, hp_ctrl->base + OCTEP_HP_INTR_OFFSET(vec_type));
         |         ^~~~~~
         |         writel


vim +190 drivers/pci/hotplug/octep_hp.c

   178	
   179	static irqreturn_t octep_hp_intr_handler(int irq, void *data)
   180	{
   181		struct octep_hp_controller *hp_ctrl = data;
   182		struct pci_dev *pdev = hp_ctrl->pdev;
   183		enum octep_hp_vec_type vec_type;
   184		struct octep_hp_cmd *hp_cmd;
   185		u64 slot_mask;
   186	
   187		vec_type = pci_irq_vector(pdev, OCTEP_HP_INTR_VECTOR(OCTEP_HP_VEC_ENA)) == irq ?
   188			OCTEP_HP_VEC_ENA : OCTEP_HP_VEC_DIS;
   189	
 > 190		slot_mask = readq(hp_ctrl->base + OCTEP_HP_INTR_OFFSET(vec_type));
   191		if (!slot_mask) {
   192			dev_err(&pdev->dev, "Invalid slot mask %llx\n", slot_mask);
   193			return IRQ_HANDLED;
   194		}
   195	
   196		hp_cmd = kzalloc(sizeof(*hp_cmd), GFP_ATOMIC);
   197		if (!hp_cmd)
   198			return IRQ_HANDLED;
   199	
   200		hp_cmd->slot_mask = slot_mask;
   201		hp_cmd->vec_type = vec_type;
   202	
   203		/* Add the command to the list and schedule the work */
   204		spin_lock(&hp_ctrl->hp_cmd_lock);
   205		list_add_tail(&hp_cmd->list, &hp_ctrl->hp_cmd_list);
   206		spin_unlock(&hp_ctrl->hp_cmd_lock);
   207		schedule_work(&hp_ctrl->work);
   208	
   209		/* Clear the interrupt */
 > 210		writeq(slot_mask, hp_ctrl->base + OCTEP_HP_INTR_OFFSET(vec_type));
   211	
   212		return IRQ_HANDLED;
   213	}
   214

>> This patch introduces a PCI hotplug controller driver for the OCTEON
>> PCIe device, a multi-function PCIe device where the first function acts
>> as a hotplug controller. It is equipped with MSI-x interrupts to notify
>> the host of hotplug events from the OCTEON firmware.
>>
>> The driver facilitates the hotplugging of non-controller functions
>> within the same device. During probe, non-controller functions are
>> removed and registered as PCI hotplug slots. The slots are added back
>> only upon request from the device firmware. The driver also allows the
>> enabling and disabling of the slots via sysfs slot entries, provided by
>> the PCI hotplug framework.
>>
>> Signed-off-by: Shijith Thotton <sthotton@marvell.com>
>> Signed-off-by: Vamsi Attunuru <vattunuru@marvell.com>
>I was curious, so drive by review.
>
>What was Vamsi's involvement?  Given Shijith sent this
>I'd guess co developer?  In which Co-developed-by tag
>should be used.
>

Will add the co-developer tag.

>Various random comments on things inline.
>
>> ---
>>
>> This patch introduces a PCI hotplug controller driver for OCTEON PCIe hotplug
>> controller. The OCTEON PCIe device is a multi-function device where the first
>> function acts as a PCI hotplug controller.
>>
>>               +--------------------------------+
>>               |           Root Port            |
>>               +--------------------------------+
>>                               |
>>                              PCIe
>>                               |
>> +---------------------------------------------------------------+
>> |              OCTEON PCIe Multifunction Device                 |
>> +---------------------------------------------------------------+
>>             |                    |              |            |
>>             |                    |              |            |
>> +---------------------+  +----------------+  +-----+  +----------------+
>> |      Function 0     |  |   Function 1   |  | ... |  |   Function 7   |
>> | (Hotplug controller)|  | (Hotplug slot) |  |     |  | (Hotplug slot) |
>> +---------------------+  +----------------+  +-----+  +----------------+
>>             |
>>             |
>> +-------------------------+
>> |   Controller Firmware   |
>> +-------------------------+
>>
>> The hotplug controller driver facilitates the hotplugging of non-controller
>> functions in the same device. During the probe of the driver, the non-
>controller
>> function are removed and registered as PCI hotplug slots. They are added
>back
>> only upon request from the device firmware. The driver also allows the user
>to
>> enable/disable the functions using sysfs slot entries provided by PCI hotplug
>> framework.
>>
>> This solution adopts a hardware + software approach for several reasons:
>>
>> 1. To reduce hardware implementation cost. Supporting complete hotplug
>>    capability within the card would require a PCI switch implemented within.
>>
>> 2. In the multi-function device, non-controller functions can act as emulated
>>    devices. The firmware can dynamically enable or disable them at runtime.
>>
>> 3. Not all root ports support PCI hotplug. This approach provides greater
>>    flexibility and compatibility across different hardware configurations.
>>
>> The hotplug controller function is lightweight and is equipped with MSI-x
>> interrupts to notify the host about hotplug events. Upon receiving an
>> interrupt, the hotplug register is read, and the required function is enabled
>> or disabled.
>>
>> This driver will be beneficial for managing PCI hotplug events on the OCTEON
>> PCIe device without requiring complex hardware solutions.
>>
>>  MAINTAINERS                    |   6 +
>>  drivers/pci/hotplug/Kconfig    |  10 +
>>  drivers/pci/hotplug/Makefile   |   1 +
>>  drivers/pci/hotplug/octep_hp.c | 351
>+++++++++++++++++++++++++++++++++
>>  4 files changed, 368 insertions(+)
>>  create mode 100644 drivers/pci/hotplug/octep_hp.c
>>
>
>
>> diff --git a/drivers/pci/hotplug/octep_hp.c b/drivers/pci/hotplug/octep_hp.c
>> new file mode 100644
>> index 000000000000..efeb542d4993
>> --- /dev/null
>> +++ b/drivers/pci/hotplug/octep_hp.c
>> @@ -0,0 +1,351 @@
>
>> +struct octep_hp_controller {
>> +	void __iomem *base;
>> +	struct pci_dev *pdev;
>> +	struct work_struct work;
>> +	struct list_head slot_list;
>> +	struct mutex slot_lock; /* Protects slot_list */
>> +	struct list_head hp_cmd_list;
>> +	spinlock_t hp_cmd_lock; /* Protects hp_cmd_list */
>> +};
>
>> +static void octep_hp_disable_pdev(struct octep_hp_controller *hp_ctrl,
>> +				  struct octep_hp_slot *hp_slot)
>> +{
>> +	mutex_lock(&hp_ctrl->slot_lock);
>
>guard(mutex)(&hp_ctrl->slot_lock);
>
>Same for other simple cases where we can avoid explicit unlock in error paths
>+ main path.
>
>

Will change to use guard.

>> +	if (!hp_slot->hp_pdev) {
>> +		dev_dbg(&hp_ctrl->pdev->dev, "Slot %u already disabled\n",
>hp_slot->slot_number);
>> +		mutex_unlock(&hp_ctrl->slot_lock);
>> +		return;
>> +	}
>> +
>> +	dev_dbg(&hp_slot->hp_pdev->dev, "Disabling slot %u\n", hp_slot-
>>slot_number);
>> +
>> +	/* Remove the device from the bus */
>> +	pci_stop_and_remove_bus_device_locked(hp_slot->hp_pdev);
>> +	hp_slot->hp_pdev = NULL;
>> +	mutex_unlock(&hp_ctrl->slot_lock);
>> +}
>
>> +#define SLOT_NAME_SIZE 16
>> +static int octep_hp_register_slot(struct octep_hp_controller *hp_ctrl, struct
>pci_dev *pdev,
>> +				  u16 slot_number)
>> +{
>> +	char slot_name[SLOT_NAME_SIZE];
>> +	struct octep_hp_slot *hp_slot;
>> +	int ret;
>> +
>> +	hp_slot = kzalloc(sizeof(*hp_slot), GFP_KERNEL);
>> +	if (!hp_slot)
>> +		return -ENOMEM;
>> +
>> +	hp_slot->ctrl = hp_ctrl;
>> +	hp_slot->hp_pdev = pdev;
>> +	hp_slot->hp_devfn = pdev->devfn;
>> +	hp_slot->slot_number = slot_number;
>> +	hp_slot->slot.ops = &octep_hp_slot_ops;
>> +
>> +	snprintf(slot_name, SLOT_NAME_SIZE, "octep_hp_%u", slot_number);
>> +	ret = pci_hp_register(&hp_slot->slot, hp_ctrl->pdev->bus,
>PCI_SLOT(pdev->devfn), slot_name);
>> +	if (ret) {
>> +		dev_err(&pdev->dev, "Failed to register hotplug slot %u\n",
>slot_number);
>> +		kfree(hp_slot);
>> +		return ret;
>		return dev_err_probe() in here as well.
>

Will change.

>> +	}
>> +
>> +	octep_hp_disable_pdev(hp_ctrl, hp_slot);
>> +	list_add_tail(&hp_slot->list, &hp_ctrl->slot_list);
>> +
>> +	return 0;
>> +}
>> +
>> +static bool octep_hp_slot(struct octep_hp_controller *hp_ctrl, struct pci_dev
>*pdev)
>> +{
>> +	/* Check if the PCI device can be hotplugged */
>> +	return pdev != hp_ctrl->pdev && pdev->bus == hp_ctrl->pdev->bus &&
>> +		PCI_SLOT(pdev->devfn) == PCI_SLOT(hp_ctrl->pdev->devfn);
>> +}
>> +
>> +static void octep_hp_cmd_handler(struct octep_hp_controller *hp_ctrl,
>struct octep_hp_cmd *hp_cmd)
>
>Line break as that's getting long for little reason.
>

Okay. Will also change other places that cross  the 80 mark.

>> +{
>> +	struct octep_hp_slot *hp_slot;
>> +
>> +	/* Enable or disable the slots based on the slot mask */
>> +	list_for_each_entry(hp_slot, &hp_ctrl->slot_list, list) {
>> +		if (hp_cmd->slot_mask & BIT(hp_slot->slot_number)) {
>> +			if (hp_cmd->vec_type == OCTEP_HP_VEC_ENA)
>> +				octep_hp_enable_pdev(hp_ctrl, hp_slot);
>> +			else
>> +				octep_hp_disable_pdev(hp_ctrl, hp_slot);
>> +		}
>> +	}
>> +}
>> +
>> +static void octep_hp_work_handler(struct work_struct *work)
>> +{
>> +	struct octep_hp_controller *hp_ctrl = container_of(work, struct
>octep_hp_controller, work);
>
>Add a line break.
>

Okay.

>> +	struct octep_hp_cmd *hp_cmd;
>> +	unsigned long flags;
>
>...
>
>> +
>> +static void octep_hp_deregister_slots(struct octep_hp_controller *hp_ctrl)
>> +{
>> +	struct octep_hp_slot *hp_slot, *tmp;
>> +
>> +	/* Deregister all the hotplug slots */
>> +	list_for_each_entry_safe(hp_slot, tmp, &hp_ctrl->slot_list, list) {
>> +		pci_hp_deregister(&hp_slot->slot);
>> +		octep_hp_enable_pdev(hp_ctrl, hp_slot);
>> +		list_del(&hp_slot->list);
>> +		kfree(hp_slot);
>
>As below, maybe just register cleanup for one slot at a time.
>That will need a bit of magic to get form the slot to the hp_ctrl though.
>
>Plus point is simpler logic to follow.
>
>

Will change.

>> +	}
>> +}
>> +
>> +static void octep_hp_controller_cleanup(void *data)
>> +{
>> +	struct octep_hp_controller *hp_ctrl = data;
>> +
>> +	pci_free_irq_vectors(hp_ctrl->pdev);
>> +	flush_work(&hp_ctrl->work);
>I'd prefer to see this broken up so we have
>simple steps.
>1. Add action 1 in probe.
>2. Add cleanup for action 1 in probe
>3. Add action 2 in probe etc.
>
>Otherwise it can be a bit tricky to review.
>

Will break the cleanup to IRQ and slot specific.

>> +	octep_hp_deregister_slots(hp_ctrl);
>
>This is particular is no where near the place where the
>slots are registered.
>May be better to register one cleanup function call
>per slot as then it will also be nice and simple to follow.
>
>

Will change to cleanup per slot.

>> +}
>> +
>> +static int octep_hp_controller_setup(struct pci_dev *pdev, struct
>octep_hp_controller *hp_ctrl)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	int ret;
>> +
>> +	ret = pcim_enable_device(pdev);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to enable PCI device\n");
>Only called from probe, so
>		return dev_err_probe()
>
>> +		return ret;
>> +	}
>> +
>> +	ret = pcim_iomap_regions(pdev, BIT(0), OCTEP_HP_DRV_NAME);
>Given there is a patch on list deprecating this, reconsider.
> https://lore.kernel.org/all/20240807083018.8734-2-pstanner@redhat.com/ 
>+CC Philipp
>

Okay. The API is available in origin/devres branch.  Will rebase on top of it.

>> +	if (ret) {
>> +		dev_err(dev, "Failed to request MMIO region\n");
>> +		return ret;
>
>Same thing on return dev_err_probe here and later.
>

Will change.

>> +	}
>> +
>> +	pci_set_master(pdev);
>> +	pci_set_drvdata(pdev, hp_ctrl);
>> +
>> +	INIT_LIST_HEAD(&hp_ctrl->slot_list);
>> +	INIT_LIST_HEAD(&hp_ctrl->hp_cmd_list);
>> +	mutex_init(&hp_ctrl->slot_lock);
>> +	spin_lock_init(&hp_ctrl->hp_cmd_lock);
>> +	INIT_WORK(&hp_ctrl->work, octep_hp_work_handler);
>> +
>> +	hp_ctrl->pdev = pdev;
>> +	hp_ctrl->base = pcim_iomap_table(pdev)[0];
>> +	if (!hp_ctrl->base) {
>> +		dev_err(dev, "Failed to get device resource map\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	ret = pci_alloc_irq_vectors(pdev, 1,
>OCTEP_HP_INTR_VECTOR(OCTEP_HP_VEC_DIS) + 1,
>> +				    PCI_IRQ_MSIX);
>> +	if (ret < 0) {
>> +		dev_err(dev, "Failed to alloc MSI-X vectors");
>> +		return ret;
>> +	}
>> +
>> +	ret = devm_add_action(dev, octep_hp_controller_cleanup, hp_ctrl);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to add action for controller cleanup\n");
>> +		return ret;
>> +	}
>> +
>> +	ret = devm_request_irq(dev, pci_irq_vector(pdev,
>OCTEP_HP_INTR_VECTOR(OCTEP_HP_VEC_ENA)),
>> +			       octep_hp_intr_handler, 0, "octep_hp_ena",
>hp_ctrl);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to register slot enable interrupt
>handle\n");
>> +		return ret;
>> +	}
>> +
>> +	ret = devm_request_irq(dev, pci_irq_vector(pdev,
>OCTEP_HP_INTR_VECTOR(OCTEP_HP_VEC_DIS)),
>> +			       octep_hp_intr_handler, 0, "octep_hp_dis", hp_ctrl);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to register slot disable interrupt
>handle\n");
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int octep_hp_pci_probe(struct pci_dev *pdev, const struct
>pci_device_id *id)
>> +{
>> +	struct octep_hp_controller *hp_ctrl;
>> +	struct pci_dev *tmp_pdev = NULL;
>> +	u16 slot_number = 0;
>> +	int ret;
>> +
>> +	hp_ctrl = devm_kzalloc(&pdev->dev, sizeof(*hp_ctrl), GFP_KERNEL);
>> +	if (!hp_ctrl)
>> +		return -ENOMEM;
>> +
>> +	ret = octep_hp_controller_setup(pdev, hp_ctrl);
>> +	if (ret) {
>> +		dev_err(&pdev->dev, "Failed to setup octep controller\n");
>> +		return ret;
>return dev_err_probe()
>actually no. Drop it. There are more informative error prints for all the
>conditions. We probably don't care that the end result is this specific
>function fails (more than an irq request failed etc).
>

Okay.

>
>> +	}
>> +
>> +	/*
>> +	 * Register all hotplug slots. Hotplug controller is the first function of
>the PCI device.
>> +	 * The hotplug slots are the remaining functions of the PCI device. They
>are removed from
>> +	 * the bus and are added back when the hotplug event is triggered.
>> +	 */
>> +	for_each_pci_dev(tmp_pdev) {
>> +		if (octep_hp_slot(hp_ctrl, tmp_pdev)) {
>What IIpo said on this.  No one likes deep indent ;)
>> +			ret = octep_hp_register_slot(hp_ctrl, tmp_pdev,
>slot_number++);
>> +			if (ret) {
>> +				dev_err(&pdev->dev, "Failed to register
>hotplug slots.\n");
>> +				return ret;
>
>return dev_err_probe();
>
>Cleaner in general even if no chance of deferral.
>
>
>
>> +			}
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +#define OCTEP_DEVID_HP_CONTROLLER 0xa0e3
>> +static struct pci_device_id octep_hp_pci_map[] = {
>> +	{ PCI_DEVICE(PCI_VENDOR_ID_CAVIUM,
>OCTEP_DEVID_HP_CONTROLLER) },
>> +	{ 0 },
>
>{ }
>Is sufficient. I can't remember if that's common style in PCI or not though.
>

Will change.

>> +};

Thanks for the review.
Shijith

>>> This patch introduces a PCI hotplug controller driver for the OCTEON
>>> PCIe device, a multi-function PCIe device where the first function acts
>>> as a hotplug controller. It is equipped with MSI-x interrupts to notify
>>> the host of hotplug events from the OCTEON firmware.
>>>
>>> The driver facilitates the hotplugging of non-controller functions
>>> within the same device. During probe, non-controller functions are
>>> removed and registered as PCI hotplug slots. The slots are added back
>>> only upon request from the device firmware. The driver also allows the
>>> enabling and disabling of the slots via sysfs slot entries, provided by
>>> the PCI hotplug framework.
>>>
>>> Signed-off-by: Shijith Thotton <sthotton@marvell.com>
>>> Signed-off-by: Vamsi Attunuru <vattunuru@marvell.com>
>>I was curious, so drive by review.
>>
>>What was Vamsi's involvement?  Given Shijith sent this
>>I'd guess co developer?  In which Co-developed-by tag
>>should be used.
>>
...
>>> +}
>>> +
>>> +static int octep_hp_controller_setup(struct pci_dev *pdev, struct
>>octep_hp_controller *hp_ctrl)
>>> +{
>>> +	struct device *dev = &pdev->dev;
>>> +	int ret;
>>> +
>>> +	ret = pcim_enable_device(pdev);
>>> +	if (ret) {
>>> +		dev_err(dev, "Failed to enable PCI device\n");
>>Only called from probe, so
>>		return dev_err_probe()
>>
>>> +		return ret;
>>> +	}
>>> +
>>> +	ret = pcim_iomap_regions(pdev, BIT(0), OCTEP_HP_DRV_NAME);
>>Given there is a patch on list deprecating this, reconsider.
>> https://lore.kernel.org/all/20240807083018.8734-2-
>pstanner@redhat.com/
>>+CC Philipp
>>
>
>Okay. The API is available in origin/devres branch.  Will rebase on top of it.
>

I forgot about the kernel test robot.
I'll hold off on making this change until the patch is merged into pci/next.