[v3,02/12] mailbox: Add Tegra HSP driver

From: Thierry Reding <treding@nvidia.com>

This driver exposes a mailbox interface for interprocessor communication
using the Hardware Synchronization Primitives (HSP) module's doorbell
mechanism. There are multiple HSP instances and they provide additional
features such as shared mailboxes, shared and arbitrated semaphores.

A driver for a remote processor can use the mailbox client provided by
the HSP driver and build an IPC protocol on top of this synchronization
mechanism.

Based on work by Joseph Lo <josephl@nvidia.com>.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
Changes in v3:
- use a more object oriented design
- fix some locking issues

 drivers/mailbox/Kconfig     |   9 +
 drivers/mailbox/Makefile    |   2 +
 drivers/mailbox/tegra-hsp.c | 561 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 572 insertions(+)
 create mode 100644 drivers/mailbox/tegra-hsp.c

On Friday, August 19, 2016 7:32:23 PM CEST Thierry Reding wrote:
> +static int tegra_hsp_doorbell_send_data(struct tegra_hsp_channel *channel,
> +                                       void *data)
> +{
> +       tegra_hsp_channel_writel(channel, 1, HSP_DB_TRIGGER);
> +
> +       return 0;
> +}
> 

It seems very odd that you don't write the data at all but just trigger
the communication here. My interpretation is that you bypass
the mailbox infrastructure for the actual message, and instead reimplement
it on top of the mailbox infrastructure as part of the bpmp driver.

Why not expose the bpmp itself as the mailbox here?

	Arnd

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On Mon, Aug 22, 2016 at 03:43:23PM +0200, Arnd Bergmann wrote:
> On Friday, August 19, 2016 7:32:23 PM CEST Thierry Reding wrote:
> > +static int tegra_hsp_doorbell_send_data(struct tegra_hsp_channel *channel,
> > +                                       void *data)
> > +{
> > +       tegra_hsp_channel_writel(channel, 1, HSP_DB_TRIGGER);
> > +
> > +       return 0;
> > +}
> > 
> 
> It seems very odd that you don't write the data at all but just trigger
> the communication here. My interpretation is that you bypass
> the mailbox infrastructure for the actual message, and instead reimplement
> it on top of the mailbox infrastructure as part of the bpmp driver.
> 
> Why not expose the bpmp itself as the mailbox here?

My understanding is that doorbell doesn't provide any means to transfer
data. It merely signals the availability of data. It is up to a use-case
specific implementation to arrange for the transport of data.

BPMP implements a shmem-based protocol and uses the doorbell merely as a
mechanism for the BPMP and CPU to signal each other when data is ready.

Exposing the BPMP as the mailbox could possibly be done, but it would
implement a fairly large software layer in the mailbox system which is
targetted primarily at simple mailbox hardware that exchanges small
amounts of data (usually fitting into 32 bits). mailbox-sti is another
driver that uses the framework only to signal, so this doesn't seem to
be a mechanism exclusive to Tegra.

Thierry

On 08/22/2016 08:17 AM, Thierry Reding wrote:
> On Mon, Aug 22, 2016 at 03:43:23PM +0200, Arnd Bergmann wrote:
>> On Friday, August 19, 2016 7:32:23 PM CEST Thierry Reding wrote:
>>> +static int tegra_hsp_doorbell_send_data(struct tegra_hsp_channel *channel,
>>> +                                       void *data)
>>> +{
>>> +       tegra_hsp_channel_writel(channel, 1, HSP_DB_TRIGGER);
>>> +
>>> +       return 0;
>>> +}
>>>
>>
>> It seems very odd that you don't write the data at all but just trigger
>> the communication here. My interpretation is that you bypass
>> the mailbox infrastructure for the actual message, and instead reimplement
>> it on top of the mailbox infrastructure as part of the bpmp driver.
>>
>> Why not expose the bpmp itself as the mailbox here?
>
> My understanding is that doorbell doesn't provide any means to transfer
> data. It merely signals the availability of data. It is up to a use-case
> specific implementation to arrange for the transport of data.

Yes, the doorbell doesn't transfer any data.

> BPMP implements a shmem-based protocol and uses the doorbell merely as a
> mechanism for the BPMP and CPU to signal each other when data is ready.
>
> Exposing the BPMP as the mailbox could possibly be done, but it would
> implement a fairly large software layer in the mailbox system which is
> targetted primarily at simple mailbox hardware that exchanges small
> amounts of data (usually fitting into 32 bits). mailbox-sti is another
> driver that uses the framework only to signal, so this doesn't seem to
> be a mechanism exclusive to Tegra.

I also don't think that in-memory IPC mechanisms are what the mailbox 
subsystem is all about; it's about pure HW mechanisms that transfer data.
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On 08/19/2016 11:32 AM, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
>
> This driver exposes a mailbox interface for interprocessor communication
> using the Hardware Synchronization Primitives (HSP) module's doorbell
> mechanism. There are multiple HSP instances and they provide additional
> features such as shared mailboxes, shared and arbitrated semaphores.
>
> A driver for a remote processor can use the mailbox client provided by
> the HSP driver and build an IPC protocol on top of this synchronization
> mechanism.

> +static int tegra_hsp_doorbell_startup(struct tegra_hsp_channel *channel)
...
> +	spin_lock_irqsave(&hsp->lock, flags);
> +
> +	value = tegra_hsp_channel_readl(&ccplex->channel, HSP_DB_ENABLE);
> +	value |= BIT(db->master);
> +	tegra_hsp_channel_writel(&ccplex->channel, value, HSP_DB_ENABLE);
> +
> +	spin_unlock_irqrestore(&hsp->lock, flags);
> +
> +	if (!tegra_hsp_doorbell_can_ring(db))
> +		return -ENODEV;

Should the error-check happen before enabling the RX path? Otherwise, 
presumably that HSP_DB_ENABLE bit should be cleared on failure.

> +static int tegra_hsp_probe(struct platform_device *pdev)

> +	dev_dbg(&pdev->dev, "regs: %pR (%p-%p)\n", res, hsp->regs, hsp->regs + resource_size(res) - 1);

Line width?
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On Fri, Aug 19, 2016 at 07:32:23PM +0200, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> This driver exposes a mailbox interface for interprocessor communication
> using the Hardware Synchronization Primitives (HSP) module's doorbell
> mechanism. There are multiple HSP instances and they provide additional
> features such as shared mailboxes, shared and arbitrated semaphores.
> 
> A driver for a remote processor can use the mailbox client provided by
> the HSP driver and build an IPC protocol on top of this synchronization
> mechanism.
> 
> Based on work by Joseph Lo <josephl@nvidia.com>.
> 
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
> Changes in v3:
> - use a more object oriented design
> - fix some locking issues
> 
>  drivers/mailbox/Kconfig     |   9 +
>  drivers/mailbox/Makefile    |   2 +
>  drivers/mailbox/tegra-hsp.c | 561 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 572 insertions(+)
>  create mode 100644 drivers/mailbox/tegra-hsp.c
> 
> diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
> index 97c372908e78..90e7b94a1199 100644
> --- a/drivers/mailbox/Kconfig
> +++ b/drivers/mailbox/Kconfig
> @@ -114,6 +114,15 @@ config MAILBOX_TEST
>  	  Test client to help with testing new Controller driver
>  	  implementations.
>  
> +config TEGRA_HSP_MBOX
> +	bool "Tegra HSP(Hardware Synchronization Primitives) Driver"
> +	depends on ARCH_TEGRA_186_SOC
> +	help
> +	  The Tegra HSP driver is used for the interprocessor communication
> +	  between different remote processors and host processors on Tegra186
> +	  and later SoCs. Say Y here if you want to have this support.
> +	  If unsure say N.
> +
>  config XGENE_SLIMPRO_MBOX
>  	tristate "APM SoC X-Gene SLIMpro Mailbox Controller"
>  	depends on ARCH_XGENE
> diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
> index 66c38e300dfc..3fa01673f288 100644
> --- a/drivers/mailbox/Makefile
> +++ b/drivers/mailbox/Makefile
> @@ -27,3 +27,5 @@ obj-$(CONFIG_XGENE_SLIMPRO_MBOX) += mailbox-xgene-slimpro.o
>  obj-$(CONFIG_HI6220_MBOX)	+= hi6220-mailbox.o
>  
>  obj-$(CONFIG_BCM_PDC_MBOX)	+= bcm-pdc-mailbox.o
> +
> +obj-$(CONFIG_TEGRA_HSP_MBOX)	+= tegra-hsp.o
> diff --git a/drivers/mailbox/tegra-hsp.c b/drivers/mailbox/tegra-hsp.c
> new file mode 100644
> index 000000000000..8770ba9b58fe
> --- /dev/null
> +++ b/drivers/mailbox/tegra-hsp.c
> @@ -0,0 +1,561 @@
> +/*
> + * Copyright (c) 2016, NVIDIA CORPORATION.  All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + */
> +
> +#define DEBUG
> +
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/mailbox_controller.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +#include <dt-bindings/mailbox/tegra186-hsp.h>
> +
> +#define HSP_INT_DIMENSIONING	0x380
> +#define HSP_nSM_SHIFT		0
> +#define HSP_nSS_SHIFT		4
> +#define HSP_nAS_SHIFT		8
> +#define HSP_nDB_SHIFT		12
> +#define HSP_nSI_SHIFT		16
> +#define HSP_nINT_MASK		0xf
> +
> +#define HSP_DB_TRIGGER	0x0
> +#define HSP_DB_ENABLE	0x4
> +#define HSP_DB_RAW	0x8
> +#define HSP_DB_PENDING	0xc
> +
> +#define HSP_DB_CCPLEX		1
> +#define HSP_DB_BPMP		3
> +#define HSP_DB_MAX		7
> +
> +struct tegra_hsp_channel;
> +struct tegra_hsp;
> +
> +struct tegra_hsp_channel_ops {
> +	int (*send_data)(struct tegra_hsp_channel *channel, void *data);
> +	int (*startup)(struct tegra_hsp_channel *channel);
> +	void (*shutdown)(struct tegra_hsp_channel *channel);
> +	bool (*last_tx_done)(struct tegra_hsp_channel *channel);
> +};
> +
> +struct tegra_hsp_channel {
> +	struct tegra_hsp *hsp;
> +	const struct tegra_hsp_channel_ops *ops;
> +	struct mbox_chan *chan;
> +	void __iomem *regs;
> +};
> +
> +static struct tegra_hsp_channel *to_tegra_hsp_channel(struct mbox_chan *chan)
> +{
> +	return chan->con_priv;
> +}
> +
> +struct tegra_hsp_doorbell {
> +	struct tegra_hsp_channel channel;
> +	struct list_head list;
> +	const char *name;
> +	unsigned int master;
> +	unsigned int index;
> +};
> +
> +static struct tegra_hsp_doorbell *
> +to_tegra_hsp_doorbell(struct tegra_hsp_channel *channel)
> +{
> +	if (!channel)
> +		return NULL;
> +
> +	return container_of(channel, struct tegra_hsp_doorbell, channel);
> +}
> +
> +struct tegra_hsp_db_map {
> +	const char *name;
> +	unsigned int master;
> +	unsigned int index;
> +};
> +
> +struct tegra_hsp_soc {
> +	const struct tegra_hsp_db_map *map;
> +};
> +
> +struct tegra_hsp {
> +	const struct tegra_hsp_soc *soc;
> +	struct mbox_controller mbox;
> +	void __iomem *regs;
> +	unsigned int irq;
> +	unsigned int num_sm;
> +	unsigned int num_as;
> +	unsigned int num_ss;
> +	unsigned int num_db;
> +	unsigned int num_si;
> +	spinlock_t lock;
> +
> +	struct list_head doorbells;
> +};
> +
> +static inline struct tegra_hsp *
> +to_tegra_hsp(struct mbox_controller *mbox)
> +{
> +	return container_of(mbox, struct tegra_hsp, mbox);
> +}
> +
> +static inline u32 tegra_hsp_readl(struct tegra_hsp *hsp, unsigned int offset)
> +{
> +	return readl(hsp->regs + offset);
> +}
> +
> +static inline void tegra_hsp_writel(struct tegra_hsp *hsp, u32 value,
> +				    unsigned int offset)
> +{
> +	writel(value, hsp->regs + offset);
> +	(void)readl(hsp->regs + offset);

I am not aware of a need for such barriers (even if the downstream code
has them).

> +}
> +
> +static inline u32 tegra_hsp_channel_readl(struct tegra_hsp_channel *channel,
> +					  unsigned int offset)
> +{
> +	return readl(channel->regs + offset);
> +}
> +
> +static inline void tegra_hsp_channel_writel(struct tegra_hsp_channel *channel,
> +					    u32 value, unsigned int offset)
> +{
> +	writel(value, channel->regs + offset);
> +	(void)readl(channel->regs + offset);

same here.

> +}
> +
> +static int tegra_hsp_doorbell_can_ring(struct tegra_hsp_doorbell *db)
> +{
> +	u32 value;
> +
> +	value = tegra_hsp_channel_readl(&db->channel, HSP_DB_ENABLE);
> +
> +	return !!(value & BIT(TEGRA_HSP_DB_MASTER_CCPLEX));
> +}
> +
> +static struct tegra_hsp_doorbell *
> +__tegra_hsp_doorbell_get(struct tegra_hsp *hsp, unsigned int master)
> +{
> +	struct tegra_hsp_doorbell *db = NULL, *entry;
> +
> +	list_for_each_entry(entry, &hsp->doorbells, list)
> +		if (entry->master == master) {

you might as well say: 'return entry;' and remove 'db' ?

> +			db = entry;
> +			break;
> +		}
> +
> +	return db;
> +}
> +
> +static struct tegra_hsp_doorbell *
> +tegra_hsp_doorbell_get(struct tegra_hsp *hsp, unsigned int master)
> +{
> +	struct tegra_hsp_doorbell *db;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&hsp->lock, flags);
> +	db = __tegra_hsp_doorbell_get(hsp, master);
> +	spin_unlock_irqrestore(&hsp->lock, flags);
> +
> +	return db;
> +}
> +
> +static irqreturn_t tegra_hsp_doorbell_irq(int irq, void *data)
> +{
> +	struct tegra_hsp *hsp = data;
> +	struct tegra_hsp_doorbell *db;
> +	unsigned long master, value;
> +
> +	db = tegra_hsp_doorbell_get(hsp, TEGRA_HSP_DB_MASTER_CCPLEX);
> +	if (!db)
> +		return IRQ_NONE;
> +
> +	value = tegra_hsp_channel_readl(&db->channel, HSP_DB_PENDING);
> +	tegra_hsp_channel_writel(&db->channel, value, HSP_DB_PENDING);
> +
> +	spin_lock(&hsp->lock);
> +
> +	for_each_set_bit(master, &value, hsp->mbox.num_chans) {
> +		struct tegra_hsp_doorbell *db;
> +
> +		db = __tegra_hsp_doorbell_get(hsp, master);
> +		if (db)
> +			mbox_chan_received_data(db->channel.chan, NULL);
> +	}
> +
> +	spin_unlock(&hsp->lock);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int tegra_hsp_doorbell_send_data(struct tegra_hsp_channel *channel,
> +					void *data)
> +{
> +	tegra_hsp_channel_writel(channel, 1, HSP_DB_TRIGGER);
> +
> +	return 0;
> +}
> +
> +static int tegra_hsp_doorbell_startup(struct tegra_hsp_channel *channel)
> +{
> +	struct tegra_hsp_doorbell *db = to_tegra_hsp_doorbell(channel);
> +	struct tegra_hsp *hsp = channel->hsp;
> +	struct tegra_hsp_doorbell *ccplex;
> +	unsigned long flags;
> +	u32 value;
> +
> +	dev_dbg(hsp->mbox.dev, "> %s(channel=%p)\n", __func__, channel);
> +	dev_dbg(hsp->mbox.dev, "  regs: %p\n", channel->regs);
> +
> +	if (db->master >= hsp->mbox.num_chans) {
> +		dev_err(hsp->mbox.dev,
> +			"invalid master ID %u for HSP channel\n",
> +			db->master);
> +		return -EINVAL;
> +	}
> +
> +	ccplex = tegra_hsp_doorbell_get(hsp, TEGRA_HSP_DB_MASTER_CCPLEX);
> +	if (!ccplex)
> +		return -ENODEV;
> +
> +	spin_lock_irqsave(&hsp->lock, flags);
> +
> +	value = tegra_hsp_channel_readl(&ccplex->channel, HSP_DB_ENABLE);
> +	value |= BIT(db->master);
> +	tegra_hsp_channel_writel(&ccplex->channel, value, HSP_DB_ENABLE);
> +
> +	spin_unlock_irqrestore(&hsp->lock, flags);
> +
> +	if (!tegra_hsp_doorbell_can_ring(db))
> +		return -ENODEV;
> +
> +	dev_dbg(hsp->mbox.dev, "< %s()\n", __func__);
> +	return 0;
> +}
> +
> +static void tegra_hsp_doorbell_shutdown(struct tegra_hsp_channel *channel)
> +{
> +	struct tegra_hsp_doorbell *db = to_tegra_hsp_doorbell(channel);
> +	struct tegra_hsp *hsp = channel->hsp;
> +	struct tegra_hsp_doorbell *ccplex;
> +	unsigned long flags;
> +	u32 value;
> +
> +	ccplex = tegra_hsp_doorbell_get(hsp, TEGRA_HSP_DB_MASTER_CCPLEX);
> +	if (!ccplex)
> +		return;
> +
> +	spin_lock_irqsave(&hsp->lock, flags);
> +
> +	value = tegra_hsp_channel_readl(&ccplex->channel, HSP_DB_ENABLE);
> +	value &= ~BIT(db->master);
> +	tegra_hsp_channel_writel(&ccplex->channel, value, HSP_DB_ENABLE);
> +
> +	spin_unlock_irqrestore(&hsp->lock, flags);
> +}
> +
> +static bool tegra_hsp_doorbell_last_tx_done(struct tegra_hsp_channel *channel)
> +{
> +	return true;
> +}
> +
> +static const struct tegra_hsp_channel_ops tegra_hsp_doorbell_ops = {
> +	.send_data = tegra_hsp_doorbell_send_data,
> +	.startup = tegra_hsp_doorbell_startup,
> +	.shutdown = tegra_hsp_doorbell_shutdown,
> +	.last_tx_done = tegra_hsp_doorbell_last_tx_done,
> +};
> +
> +static struct tegra_hsp_channel *
> +tegra_hsp_doorbell_create(struct tegra_hsp *hsp, const char *name,
> +			  unsigned int master, unsigned int index)
> +{
> +	struct tegra_hsp_doorbell *db;
> +	unsigned int offset;
> +	unsigned long flags;
> +
> +	db = kzalloc(sizeof(*db), GFP_KERNEL);
> +	if (!db)
> +		return ERR_PTR(-ENOMEM);
> +
> +	offset = (1 + (hsp->num_sm / 2) + hsp->num_ss + hsp->num_as) << 16;
> +	offset += index * 0x100;
> +
> +	db->channel.ops = &tegra_hsp_doorbell_ops;
> +	db->channel.regs = hsp->regs + offset;
> +	db->channel.hsp = hsp;
> +
> +	db->name = kstrdup_const(name, GFP_KERNEL);
> +	db->master = master;
> +	db->index = index;
> +
> +	spin_lock_irqsave(&hsp->lock, flags);
> +	list_add_tail(&db->list, &hsp->doorbells);
> +	spin_unlock_irqrestore(&hsp->lock, flags);
> +
> +	return &db->channel;
> +}
> +
> +static void __tegra_hsp_doorbell_destroy(struct tegra_hsp_doorbell *db)
> +{
> +	list_del(&db->list);
> +	kfree_const(db->name);
> +	kfree(db);
> +}
> +
> +static int tegra_hsp_send_data(struct mbox_chan *chan, void *data)
> +{
> +	struct tegra_hsp_channel *channel = to_tegra_hsp_channel(chan);
> +
> +	return channel->ops->send_data(channel, data);
> +}
> +
> +static int tegra_hsp_startup(struct mbox_chan *chan)
> +{
> +	struct tegra_hsp_channel *channel = to_tegra_hsp_channel(chan);
> +
> +	return channel->ops->startup(channel);
> +}
> +
> +static void tegra_hsp_shutdown(struct mbox_chan *chan)
> +{
> +	struct tegra_hsp_channel *channel = to_tegra_hsp_channel(chan);
> +
> +	return channel->ops->shutdown(channel);
> +}
> +
> +static bool tegra_hsp_last_tx_done(struct mbox_chan *chan)
> +{
> +	struct tegra_hsp_channel *channel = to_tegra_hsp_channel(chan);
> +
> +	return channel->ops->last_tx_done(channel);
> +}
> +
> +static const struct mbox_chan_ops tegra_hsp_ops = {
> +	.send_data = tegra_hsp_send_data,
> +	.startup = tegra_hsp_startup,
> +	.shutdown = tegra_hsp_shutdown,
> +	.last_tx_done = tegra_hsp_last_tx_done,
> +};
> +
> +static struct mbox_chan *of_tegra_hsp_xlate(struct mbox_controller *mbox,
> +					    const struct of_phandle_args *args)
> +{
> +	struct tegra_hsp *hsp = to_tegra_hsp(mbox);
> +	struct tegra_hsp_channel *channel = ERR_PTR(-ENODEV);
> +	unsigned int type = args->args[0];
> +	unsigned int master = args->args[1];
> +	struct tegra_hsp_doorbell *db;
> +	struct mbox_chan *chan;
> +	unsigned long flags;
> +	unsigned int i;
> +
> +	dev_dbg(mbox->dev, "> %s(mbox=%p, args=%p)\n", __func__, mbox, args);
> +	dev_dbg(mbox->dev, "  type: %x, master: %x\n", type, master);
> +
> +	switch (type) {
> +	case TEGRA_HSP_MBOX_TYPE_DB:
> +		db = tegra_hsp_doorbell_get(hsp, master);
> +		dev_dbg(mbox->dev, "  doorbell: %p\n", db);
> +		if (db)
> +			channel = &db->channel;
> +
> +		break;
> +
> +	default:
> +		break;
> +	}
> +
> +	if (IS_ERR(channel))
> +		return ERR_CAST(channel);
> +
> +	spin_lock_irqsave(&hsp->lock, flags);
> +
> +	for (i = 0; i < hsp->mbox.num_chans; i++) {
> +		chan = &hsp->mbox.chans[i];
> +		if (!chan->con_priv) {
> +			chan->con_priv = channel;
> +			channel->chan = chan;
> +			break;
> +		}
> +
> +		chan = NULL;
> +	}
> +
> +	spin_unlock_irqrestore(&hsp->lock, flags);
> +
> +	dev_dbg(mbox->dev, "< %s() = %p\n", __func__, chan);
> +	return chan ?: ERR_PTR(-EBUSY);
> +}
> +
> +static void tegra_hsp_remove_doorbells(struct tegra_hsp *hsp)
> +{
> +	struct tegra_hsp_doorbell *db;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&hsp->lock, flags);
> +
> +	list_for_each_entry(db, &hsp->doorbells, list)
> +		__tegra_hsp_doorbell_destroy(db);
> +
> +	spin_unlock_irqrestore(&hsp->lock, flags);
> +}
> +
> +static int tegra_hsp_add_doorbells(struct tegra_hsp *hsp)
> +{
> +	const struct tegra_hsp_db_map *map = hsp->soc->map;
> +	struct tegra_hsp_channel *channel;
> +
> +	dev_dbg(hsp->mbox.dev, "> %s(hsp=%p)\n", __func__, hsp);
> +
> +	while (map->name) {
> +		dev_dbg(hsp->mbox.dev, "  adding doorbell for master %u (%s), index %u\n", map->master, map->name, map->index);
> +
> +		channel = tegra_hsp_doorbell_create(hsp, map->name,
> +						    map->master, map->index);
> +		if (IS_ERR(channel)) {
> +			tegra_hsp_remove_doorbells(hsp);
> +			return PTR_ERR(channel);
> +		}
> +
> +		map++;
> +	}
> +
> +	dev_dbg(hsp->mbox.dev, "< %s()\n", __func__);
> +	return 0;
> +}
> +
> +static int tegra_hsp_probe(struct platform_device *pdev)
> +{
> +	struct tegra_hsp *hsp;
> +	struct resource *res;
> +	u32 value;
> +	int err;
> +
> +	dev_dbg(&pdev->dev, "> %s(pdev=%p)\n", __func__, pdev);
> +
> +	hsp = devm_kzalloc(&pdev->dev, sizeof(*hsp), GFP_KERNEL);
> +	if (!hsp)
> +		return -ENOMEM;
> +
> +	dev_dbg(&pdev->dev, "  hsp: %p\n", hsp);
> +
> +	hsp->soc = of_device_get_match_data(&pdev->dev);
> +	INIT_LIST_HEAD(&hsp->doorbells);
> +	spin_lock_init(&hsp->lock);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	hsp->regs = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(hsp->regs))
> +		return PTR_ERR(hsp->regs);
> +
> +	value = tegra_hsp_readl(hsp, HSP_INT_DIMENSIONING);
> +	hsp->num_sm = (value >> HSP_nSM_SHIFT) & HSP_nINT_MASK;
> +	hsp->num_ss = (value >> HSP_nSS_SHIFT) & HSP_nINT_MASK;
> +	hsp->num_as = (value >> HSP_nAS_SHIFT) & HSP_nINT_MASK;
> +	hsp->num_db = (value >> HSP_nDB_SHIFT) & HSP_nINT_MASK;
> +	hsp->num_si = (value >> HSP_nSI_SHIFT) & HSP_nINT_MASK;
> +
> +	dev_dbg(&pdev->dev, "regs: %pR (%p-%p)\n", res, hsp->regs, hsp->regs + resource_size(res) - 1);
> +	dev_dbg(&pdev->dev, "sm: %u ss:%u as: %u db: %u, si: %u\n",
> +		hsp->num_sm, hsp->num_ss, hsp->num_as, hsp->num_db,
> +		hsp->num_si);
> +
> +	err = platform_get_irq_byname(pdev, "doorbell");
> +	if (err < 0) {
> +		dev_err(&pdev->dev, "failed to get doorbell IRQ: %d\n", err);
> +		return err;
> +	}
> +
> +	hsp->irq = err;
> +
> +	err = devm_request_irq(&pdev->dev, hsp->irq, tegra_hsp_doorbell_irq,
> +			       IRQF_NO_SUSPEND, dev_name(&pdev->dev), hsp);
> +	if (err < 0) {
> +		dev_err(&pdev->dev, "failed to request IRQ#%u: %d\n",
> +			hsp->irq, err);
> +		return err;
> +	}
> +
> +	hsp->mbox.of_xlate = of_tegra_hsp_xlate;
> +	hsp->mbox.num_chans = 32;
> +	hsp->mbox.dev = &pdev->dev;
> +	hsp->mbox.txdone_irq = false;
> +	hsp->mbox.txdone_poll = false;
> +	hsp->mbox.ops = &tegra_hsp_ops;
> +
> +	hsp->mbox.chans = devm_kcalloc(&pdev->dev, hsp->mbox.num_chans,
> +					sizeof(*hsp->mbox.chans),
> +					GFP_KERNEL);
> +	if (!hsp->mbox.chans)
> +		return -ENOMEM;
> +
> +	err = tegra_hsp_add_doorbells(hsp);
> +	if (err < 0) {
> +		dev_err(&pdev->dev, "failed to add doorbells: %d\n", err);
> +		return err;
> +	}
> +
> +	platform_set_drvdata(pdev, hsp);
> +
> +	err = mbox_controller_register(&hsp->mbox);
> +	if (err) {
> +		dev_err(&pdev->dev, "failed to register mailbox: %d\n", err);
> +		tegra_hsp_remove_doorbells(hsp);
> +		return err;
> +	}
> +
> +	dev_dbg(&pdev->dev, "< %s()\n", __func__);
> +	return 0;
> +}
> +
> +static int tegra_hsp_remove(struct platform_device *pdev)
> +{
> +	struct tegra_hsp *hsp = platform_get_drvdata(pdev);
> +
> +	mbox_controller_unregister(&hsp->mbox);
> +	tegra_hsp_remove_doorbells(hsp);
> +
> +	return 0;
> +}
> +
> +static const struct tegra_hsp_db_map tegra186_hsp_db_map[] = {
> +	{ "ccplex", TEGRA_HSP_DB_MASTER_CCPLEX, HSP_DB_CCPLEX },
> +	{ "bpmp",   TEGRA_HSP_DB_MASTER_BPMP,   HSP_DB_BPMP   },
> +	{ /* sentinel */ }
> +};
> +
> +static const struct tegra_hsp_soc tegra186_hsp_soc = {
> +	.map = tegra186_hsp_db_map,
> +};
> +
> +static const struct of_device_id tegra_hsp_match[] = {
> +	{ .compatible = "nvidia,tegra186-hsp", .data = &tegra186_hsp_soc },
> +	{ }
> +};
> +
> +static struct platform_driver tegra_hsp_driver = {
> +	.driver = {
> +		.name = "tegra-hsp",
> +		.of_match_table = tegra_hsp_match,
> +	},
> +	.probe = tegra_hsp_probe,
> +	.remove = tegra_hsp_remove,
> +};
> +
> +static int __init tegra_hsp_init(void)
> +{
> +	return platform_driver_register(&tegra_hsp_driver);
> +}
> +core_initcall(tegra_hsp_init);
> -- 
> 2.9.0
> 
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On Fri, Aug 19, 2016 at 07:32:23PM +0200, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + */
> +
> +#define DEBUG

Is this a leftover from your debugging (elsewhere in this series too)?

> +
> +#include <linux/interrupt.h>
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