[v6,2/3] gpio: Cygnus: add GPIO driver
diff mbox

Message ID 1418696307-19392-3-git-send-email-rjui@broadcom.com
State Accepted
Headers show

Commit Message

Ray Jui Dec. 16, 2014, 2:18 a.m. UTC
This GPIO driver supports all 3 GPIO controllers in the Broadcom Cygnus
SoC. The 3 GPIO controllers are 1) the ASIU GPIO controller, 2) the
chipCommonG GPIO controller, and 3) the ALWAYS-ON GPIO controller

Signed-off-by: Ray Jui <rjui@broadcom.com>
Reviewed-by: Scott Branden <sbranden@broadcom.com>
---
 drivers/gpio/Kconfig           |   12 +
 drivers/gpio/Makefile          |    1 +
 drivers/gpio/gpio-bcm-cygnus.c |  607 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 620 insertions(+)
 create mode 100644 drivers/gpio/gpio-bcm-cygnus.c

Comments

Linus Walleij Jan. 13, 2015, 8:53 a.m. UTC | #1
On Tue, Dec 16, 2014 at 3:18 AM, Ray Jui <rjui@broadcom.com> wrote:

> This GPIO driver supports all 3 GPIO controllers in the Broadcom Cygnus
> SoC. The 3 GPIO controllers are 1) the ASIU GPIO controller, 2) the
> chipCommonG GPIO controller, and 3) the ALWAYS-ON GPIO controller
>
> Signed-off-by: Ray Jui <rjui@broadcom.com>
> Reviewed-by: Scott Branden <sbranden@broadcom.com>

(Big thanks to Alexandre for doing the major part of the review,
good work with following up so far!)

(...)
> +config GPIO_BCM_CYGNUS
> +       bool "Broadcom Cygnus GPIO support"
> +       depends on ARCH_BCM_CYGNUS && OF_GPIO

select GPIOLIB_IRQCHIP

See more about this below.

> +++ b/drivers/gpio/gpio-bcm-cygnus.c
> @@ -0,0 +1,607 @@
> +/*
> + * Copyright (C) 2014 Broadcom Corporation
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation version 2.
> + *
> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
> + * kind, whether express or implied; without even the implied warranty
> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/module.h>
> +#include <linux/irq.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/gpio.h>
> +#include <linux/ioport.h>
> +#include <linux/of_device.h>
> +#include <linux/of_irq.h>
> +#include <linux/irqchip/chained_irq.h>

Skip <linux/irq.h> and <linux/irqchip/chained_irq.h>
as these move to the core with GPIOLIB_IRQCHIP

> +#define CYGNUS_GPIO_DATA_IN_OFFSET   0x00
> +#define CYGNUS_GPIO_DATA_OUT_OFFSET  0x04
> +#define CYGNUS_GPIO_OUT_EN_OFFSET    0x08
> +#define CYGNUS_GPIO_IN_TYPE_OFFSET   0x0c
> +#define CYGNUS_GPIO_INT_DE_OFFSET    0x10
> +#define CYGNUS_GPIO_INT_EDGE_OFFSET  0x14
> +#define CYGNUS_GPIO_INT_MSK_OFFSET   0x18
> +#define CYGNUS_GPIO_INT_STAT_OFFSET  0x1c
> +#define CYGNUS_GPIO_INT_MSTAT_OFFSET 0x20
> +#define CYGNUS_GPIO_INT_CLR_OFFSET   0x24
> +#define CYGNUS_GPIO_PAD_RES_OFFSET   0x34
> +#define CYGNUS_GPIO_RES_EN_OFFSET    0x38
> +
> +/* drive strength control for ASIU GPIO */
> +#define CYGNUS_GPIO_ASIU_DRV0_CTRL_OFFSET 0x58
> +
> +/* drive strength control for CCM GPIO */
> +#define CYGNUS_GPIO_CCM_DRV0_CTRL_OFFSET  0x00

This stuff (drive strength) is pin control, pin config.
It does not belong in a pure GPIO driver. If you're
making a combined pin control + GPIO driver, it
shall be put in drivers/pinctrl/*

> +#define GPIO_BANK_SIZE 0x200
> +#define NGPIOS_PER_BANK 32
> +#define GPIO_BANK(pin) ((pin) / NGPIOS_PER_BANK)
> +
> +#define CYGNUS_GPIO_REG(pin, reg) (GPIO_BANK(pin) * GPIO_BANK_SIZE + (reg))
> +#define CYGNUS_GPIO_SHIFT(pin) ((pin) % NGPIOS_PER_BANK)
> +
> +#define GPIO_FLAG_BIT_MASK           0xffff
> +#define GPIO_PULL_BIT_SHIFT          16
> +#define GPIO_PULL_BIT_MASK           0x3
> +
> +#define GPIO_DRV_STRENGTH_BIT_SHIFT  20
> +#define GPIO_DRV_STRENGTH_BITS       3
> +#define GPIO_DRV_STRENGTH_BIT_MASK   ((1 << GPIO_DRV_STRENGTH_BITS) - 1)
> +
> +/*
> + * For GPIO internal pull up/down registers
> + */
> +enum gpio_pull {
> +       GPIO_PULL_NONE = 0,
> +       GPIO_PULL_UP,
> +       GPIO_PULL_DOWN,
> +       GPIO_PULL_INVALID,
> +};
> +
> +/*
> + * GPIO drive strength
> + */
> +enum gpio_drv_strength {
> +       GPIO_DRV_STRENGTH_2MA = 0,
> +       GPIO_DRV_STRENGTH_4MA,
> +       GPIO_DRV_STRENGTH_6MA,
> +       GPIO_DRV_STRENGTH_8MA,
> +       GPIO_DRV_STRENGTH_10MA,
> +       GPIO_DRV_STRENGTH_12MA,
> +       GPIO_DRV_STRENGTH_14MA,
> +       GPIO_DRV_STRENGTH_16MA,
> +       GPIO_DRV_STRENGTH_INVALID,
> +};


All this pull up/down and drive strength is pin config for
the pin control subsystem.

> +struct cygnus_gpio {
> +       struct device *dev;
> +       void __iomem *base;
> +       void __iomem *io_ctrl;
> +       spinlock_t lock;
> +       struct gpio_chip gc;
> +       unsigned num_banks;
> +       int irq;
> +       struct irq_domain *irq_domain;

Skip irq and irqdomain and use GPIOLIB_IRQCHIP

> +static u32 cygnus_readl(struct cygnus_gpio *cygnus_gpio, unsigned int offset)
> +{
> +       return readl(cygnus_gpio->base + offset);
> +}
> +
> +static void cygnus_writel(struct cygnus_gpio *cygnus_gpio,
> +                         unsigned int offset, u32 val)
> +{
> +       writel(val, cygnus_gpio->base + offset);
> +}

I don't see the value of using these accessors over just inlining
your readl/writel stuff.

(...)
> +static int cygnus_gpio_to_irq(struct gpio_chip *gc, unsigned offset)
> +{
> +       struct cygnus_gpio *cygnus_gpio = to_cygnus_gpio(gc);
> +
> +       return irq_find_mapping(cygnus_gpio->irq_domain, offset);
> +}

This goes away to the core with GPIOLIB_IRQCHIP

> +static void cygnus_gpio_irq_handler(unsigned int irq, struct irq_desc *desc)
> +{
> +       struct cygnus_gpio *cygnus_gpio;
> +       struct irq_chip *chip = irq_desc_get_chip(desc);
> +       int i, bit;
> +
> +       chained_irq_enter(chip, desc);
> +
> +       cygnus_gpio = irq_get_handler_data(irq);
> +
> +       /* go through the entire GPIO banks and handle all interrupts */
> +       for (i = 0; i < cygnus_gpio->num_banks; i++) {
> +               unsigned long val = cygnus_readl(cygnus_gpio,
> +                               (i * GPIO_BANK_SIZE) +
> +                               CYGNUS_GPIO_INT_MSTAT_OFFSET);
> +
> +               for_each_set_bit(bit, &val, NGPIOS_PER_BANK) {
> +                       unsigned pin = NGPIOS_PER_BANK * i + bit;
> +                       int child_irq =
> +                               cygnus_gpio_to_irq(&cygnus_gpio->gc, pin);
> +
> +                       /*
> +                        * Clear the interrupt before invoking the
> +                        * handler, so we do not leave any window
> +                        */
> +                       cygnus_writel(cygnus_gpio, (i * GPIO_BANK_SIZE) +
> +                               CYGNUS_GPIO_INT_CLR_OFFSET, BIT(bit));
> +
> +                       generic_handle_irq(child_irq);
> +               }
> +       }
> +
> +       chained_irq_exit(chip, desc);
> +}

Looks good, but you will need to have the struct gpio_chip * as
handler data to use GPIOLIB_IRQCHIP, so get from there to
the struct cygnus_gpio something like:

struct gpio_chip *gc = irq_desc_get_handler_data(desc);
struct cygnus_gpio *cyg = to_cygnus_gpio(gc);

> +static int cygnus_gpio_get(struct gpio_chip *gc, unsigned gpio)
> +{
> +       struct cygnus_gpio *cygnus_gpio = to_cygnus_gpio(gc);
> +       unsigned int offset = CYGNUS_GPIO_REG(gpio,
> +                       CYGNUS_GPIO_DATA_IN_OFFSET);
> +       unsigned int shift = CYGNUS_GPIO_SHIFT(gpio);
> +       u32 val;
> +
> +       val = cygnus_readl(cygnus_gpio, offset);
> +       val = (val >> shift) & 1;

No, do this:

return !!(cygnus_readl(cygnus_gpio, offset) & BIT(shift));

Maybe rename the "shift" variable to "bit" or just use the macro
directly in the readl().

> +static int cygnus_gpio_irq_map(struct irq_domain *d, unsigned int irq,
> +                              irq_hw_number_t hwirq)
> +{
> +       int ret;
> +
> +       ret = irq_set_chip_data(irq, d->host_data);
> +       if (ret < 0)
> +               return ret;
> +       irq_set_lockdep_class(irq, &gpio_lock_class);
> +       irq_set_chip_and_handler(irq, &cygnus_gpio_irq_chip,
> +                       handle_simple_irq);
> +       set_irq_flags(irq, IRQF_VALID);
> +
> +       return 0;
> +}
> +
> +static void cygnus_gpio_irq_unmap(struct irq_domain *d, unsigned int irq)
> +{
> +       irq_set_chip_and_handler(irq, NULL, NULL);
> +       irq_set_chip_data(irq, NULL);
> +}
> +
> +static struct irq_domain_ops cygnus_irq_ops = {
> +       .map = cygnus_gpio_irq_map,
> +       .unmap = cygnus_gpio_irq_unmap,
> +       .xlate = irq_domain_xlate_twocell,
> +};

All this goes away with GPIOLIB_IRQCHIP (that is what is good about it).

> +#ifdef CONFIG_OF_GPIO

What, that should be defined all the time, you depend on it in
Kconfig!

> +static void cygnus_gpio_set_pull(struct cygnus_gpio *cygnus_gpio,
> +                                unsigned gpio, enum gpio_pull pull)
(...)
> +static void cygnus_gpio_set_strength(struct cygnus_gpio *cygnus_gpio,
> +               unsigned gpio, enum gpio_drv_strength strength)
(...)
> +static int cygnus_gpio_of_xlate(struct gpio_chip *gc,
> +               const struct of_phandle_args *gpiospec, u32 *flags)

NAK. This is pin control, put this in the pin control driver.

I guess the same that is part of this patch series.

(...)
> +static int cygnus_gpio_probe(struct platform_device *pdev)
> +{
> +       struct device *dev = &pdev->dev;
> +       struct resource *res;
> +       struct cygnus_gpio *cygnus_gpio;
> +       struct gpio_chip *gc;
> +       u32 i, ngpios;
> +       int ret;
> +
> +       cygnus_gpio = devm_kzalloc(dev, sizeof(*cygnus_gpio), GFP_KERNEL);
> +       if (!cygnus_gpio)
> +               return -ENOMEM;
> +
> +       cygnus_gpio->dev = dev;
> +       platform_set_drvdata(pdev, cygnus_gpio);
> +
> +       if (of_property_read_u32(dev->of_node, "ngpios", &ngpios)) {
> +               dev_err(&pdev->dev, "missing ngpios DT property\n");
> +               return -ENODEV;
> +       }
> +       cygnus_gpio->num_banks = (ngpios + NGPIOS_PER_BANK - 1) /
> +               NGPIOS_PER_BANK;
> +
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       cygnus_gpio->base = devm_ioremap_resource(dev, res);
> +       if (IS_ERR(cygnus_gpio->base)) {
> +               dev_err(&pdev->dev, "unable to map I/O memory\n");
> +               return PTR_ERR(cygnus_gpio->base);
> +       }
> +
> +       /*
> +        * Only certain types of Cygnus GPIO interfaces have I/O control
> +        * registers
> +        */
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> +       if (res) {
> +               cygnus_gpio->io_ctrl = devm_ioremap_resource(dev, res);
> +               if (IS_ERR(cygnus_gpio->io_ctrl)) {
> +                       dev_err(&pdev->dev, "unable to map I/O memory\n");
> +                       return PTR_ERR(cygnus_gpio->io_ctrl);
> +               }
> +       }

This is a good indication that it's a separate piece of HW and should
be a separate pin control driver.

> +
> +       spin_lock_init(&cygnus_gpio->lock);
> +
> +       gc = &cygnus_gpio->gc;
> +       gc->base = -1;
> +       gc->ngpio = ngpios;
> +       gc->label = dev_name(dev);
> +       gc->dev = dev;
> +#ifdef CONFIG_OF_GPIO

You depend on this symbol.

> +       gc->of_node = dev->of_node;
> +       gc->of_gpio_n_cells = 2;
> +       gc->of_xlate = cygnus_gpio_of_xlate;
> +#endif
> +       gc->direction_input = cygnus_gpio_direction_input;
> +       gc->direction_output = cygnus_gpio_direction_output;
> +       gc->set = cygnus_gpio_set;
> +       gc->get = cygnus_gpio_get;
> +       gc->to_irq = cygnus_gpio_to_irq;
> +
> +       ret = gpiochip_add(gc);
> +       if (ret < 0) {
> +               dev_err(&pdev->dev, "unable to add GPIO chip\n");
> +               return ret;
> +       }
> +
> +       /*
> +        * Some of the GPIO interfaces do not have interrupt wired to the main
> +        * processor
> +        */
> +       cygnus_gpio->irq = platform_get_irq(pdev, 0);
> +       if (cygnus_gpio->irq < 0) {
> +               ret = cygnus_gpio->irq;
> +               if (ret == -EPROBE_DEFER)
> +                       goto err_rm_gpiochip;
> +
> +               dev_info(&pdev->dev, "no interrupt hook\n");
> +       }

From here:

> +       cygnus_gpio->irq_domain = irq_domain_add_linear(dev->of_node,
> +                       gc->ngpio, &cygnus_irq_ops, cygnus_gpio);
> +       if (!cygnus_gpio->irq_domain) {
> +               dev_err(&pdev->dev, "unable to allocate IRQ domain\n");
> +               ret = -ENXIO;
> +               goto err_rm_gpiochip;
> +       }
> +
> +       for (i = 0; i < gc->ngpio; i++) {
> +               int irq = irq_create_mapping(cygnus_gpio->irq_domain, i);
> +
> +               irq_set_lockdep_class(irq, &gpio_lock_class);
> +               irq_set_chip_data(irq, cygnus_gpio);
> +               irq_set_chip_and_handler(irq, &cygnus_gpio_irq_chip,
> +                               handle_simple_irq);
> +               set_irq_flags(irq, IRQF_VALID);
> +       }
> +
> +       irq_set_chained_handler(cygnus_gpio->irq, cygnus_gpio_irq_handler);
> +       irq_set_handler_data(cygnus_gpio->irq, cygnus_gpio);

To here, replace with a single call to
gpiochip_set_chained_irqchip(chip *, irq_chip *, irq, handler)...

Look at other drivers using GPIOLIB_IRQCHIP for inspiration.

Yours,
Linus Walleij
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Ray Jui Jan. 13, 2015, 5:05 p.m. UTC | #2
On 1/13/2015 12:53 AM, Linus Walleij wrote:
> On Tue, Dec 16, 2014 at 3:18 AM, Ray Jui <rjui@broadcom.com> wrote:
> 
>> This GPIO driver supports all 3 GPIO controllers in the Broadcom Cygnus
>> SoC. The 3 GPIO controllers are 1) the ASIU GPIO controller, 2) the
>> chipCommonG GPIO controller, and 3) the ALWAYS-ON GPIO controller
>>
>> Signed-off-by: Ray Jui <rjui@broadcom.com>
>> Reviewed-by: Scott Branden <sbranden@broadcom.com>
> 
> (Big thanks to Alexandre for doing the major part of the review,
> good work with following up so far!)
> 
> (...)
Yes, reviews from Alex and others are very helpful!

>> +config GPIO_BCM_CYGNUS
>> +       bool "Broadcom Cygnus GPIO support"
>> +       depends on ARCH_BCM_CYGNUS && OF_GPIO
> 
> select GPIOLIB_IRQCHIP
> 
> See more about this below.
> 
>> +++ b/drivers/gpio/gpio-bcm-cygnus.c
>> @@ -0,0 +1,607 @@
>> +/*
>> + * Copyright (C) 2014 Broadcom Corporation
>> + *
>> + * This program is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU General Public License as
>> + * published by the Free Software Foundation version 2.
>> + *
>> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
>> + * kind, whether express or implied; without even the implied warranty
>> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + */
>> +
>> +#include <linux/kernel.h>
>> +#include <linux/slab.h>
>> +#include <linux/module.h>
>> +#include <linux/irq.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/io.h>
>> +#include <linux/gpio.h>
>> +#include <linux/ioport.h>
>> +#include <linux/of_device.h>
>> +#include <linux/of_irq.h>
>> +#include <linux/irqchip/chained_irq.h>
> 
> Skip <linux/irq.h> and <linux/irqchip/chained_irq.h>
> as these move to the core with GPIOLIB_IRQCHIP
> 
Will do.

>> +#define CYGNUS_GPIO_DATA_IN_OFFSET   0x00
>> +#define CYGNUS_GPIO_DATA_OUT_OFFSET  0x04
>> +#define CYGNUS_GPIO_OUT_EN_OFFSET    0x08
>> +#define CYGNUS_GPIO_IN_TYPE_OFFSET   0x0c
>> +#define CYGNUS_GPIO_INT_DE_OFFSET    0x10
>> +#define CYGNUS_GPIO_INT_EDGE_OFFSET  0x14
>> +#define CYGNUS_GPIO_INT_MSK_OFFSET   0x18
>> +#define CYGNUS_GPIO_INT_STAT_OFFSET  0x1c
>> +#define CYGNUS_GPIO_INT_MSTAT_OFFSET 0x20
>> +#define CYGNUS_GPIO_INT_CLR_OFFSET   0x24
>> +#define CYGNUS_GPIO_PAD_RES_OFFSET   0x34
>> +#define CYGNUS_GPIO_RES_EN_OFFSET    0x38
>> +
>> +/* drive strength control for ASIU GPIO */
>> +#define CYGNUS_GPIO_ASIU_DRV0_CTRL_OFFSET 0x58
>> +
>> +/* drive strength control for CCM GPIO */
>> +#define CYGNUS_GPIO_CCM_DRV0_CTRL_OFFSET  0x00
> 
> This stuff (drive strength) is pin control, pin config.
> It does not belong in a pure GPIO driver. If you're
> making a combined pin control + GPIO driver, it
> shall be put in drivers/pinctrl/*
> 
Okay, I have some questions here. Are you suggesting me to register this
driver to both the pinctrl subsystem and gpiolib and move it to under
drivers/pinctrl/*? And obviously I should handle all pinctrl related
functions (drive strength, pull up/down, and etc.) using the standard
pinctrl bindings.

Or Are you suggesting me to combine this driver with the other Cygnus
pinctrl driver (which only supports pinmux)?

Note in Cygnus, all pinmux logic is done in the pinmux block. And there
are 3 GPIO controllers, that handle GPIO, drive strength of the GPIO
pins, internal pull up/down of the GPIO pins, which are handled in this
driver. So this driver is generic to all 3 GPIO controllers, as you can
see from the device tree bindings, there are 3 nodes.

Therefore, I think it makes sense to have one pinmux driver that handles
the pinmux block, and one generic pinctrl + gpio driver that handles
functions supported by all 3 GPIO controllers. Does this make sense to you?

>> +#define GPIO_BANK_SIZE 0x200
>> +#define NGPIOS_PER_BANK 32
>> +#define GPIO_BANK(pin) ((pin) / NGPIOS_PER_BANK)
>> +
>> +#define CYGNUS_GPIO_REG(pin, reg) (GPIO_BANK(pin) * GPIO_BANK_SIZE + (reg))
>> +#define CYGNUS_GPIO_SHIFT(pin) ((pin) % NGPIOS_PER_BANK)
>> +
>> +#define GPIO_FLAG_BIT_MASK           0xffff
>> +#define GPIO_PULL_BIT_SHIFT          16
>> +#define GPIO_PULL_BIT_MASK           0x3
>> +
>> +#define GPIO_DRV_STRENGTH_BIT_SHIFT  20
>> +#define GPIO_DRV_STRENGTH_BITS       3
>> +#define GPIO_DRV_STRENGTH_BIT_MASK   ((1 << GPIO_DRV_STRENGTH_BITS) - 1)
>> +
>> +/*
>> + * For GPIO internal pull up/down registers
>> + */
>> +enum gpio_pull {
>> +       GPIO_PULL_NONE = 0,
>> +       GPIO_PULL_UP,
>> +       GPIO_PULL_DOWN,
>> +       GPIO_PULL_INVALID,
>> +};
>> +
>> +/*
>> + * GPIO drive strength
>> + */
>> +enum gpio_drv_strength {
>> +       GPIO_DRV_STRENGTH_2MA = 0,
>> +       GPIO_DRV_STRENGTH_4MA,
>> +       GPIO_DRV_STRENGTH_6MA,
>> +       GPIO_DRV_STRENGTH_8MA,
>> +       GPIO_DRV_STRENGTH_10MA,
>> +       GPIO_DRV_STRENGTH_12MA,
>> +       GPIO_DRV_STRENGTH_14MA,
>> +       GPIO_DRV_STRENGTH_16MA,
>> +       GPIO_DRV_STRENGTH_INVALID,
>> +};
> 
> 
> All this pull up/down and drive strength is pin config for
> the pin control subsystem.
> 
Yes.

>> +struct cygnus_gpio {
>> +       struct device *dev;
>> +       void __iomem *base;
>> +       void __iomem *io_ctrl;
>> +       spinlock_t lock;
>> +       struct gpio_chip gc;
>> +       unsigned num_banks;
>> +       int irq;
>> +       struct irq_domain *irq_domain;
> 
> Skip irq and irqdomain and use GPIOLIB_IRQCHIP
> 
Will switch to GPIOLIB_IRQCHIP.

>> +static u32 cygnus_readl(struct cygnus_gpio *cygnus_gpio, unsigned int offset)
>> +{
>> +       return readl(cygnus_gpio->base + offset);
>> +}
>> +
>> +static void cygnus_writel(struct cygnus_gpio *cygnus_gpio,
>> +                         unsigned int offset, u32 val)
>> +{
>> +       writel(val, cygnus_gpio->base + offset);
>> +}
> 
> I don't see the value of using these accessors over just inlining
> your readl/writel stuff.
> 
> (...)
Hmmm....I can change this back to simply readl/writel

>> +static int cygnus_gpio_to_irq(struct gpio_chip *gc, unsigned offset)
>> +{
>> +       struct cygnus_gpio *cygnus_gpio = to_cygnus_gpio(gc);
>> +
>> +       return irq_find_mapping(cygnus_gpio->irq_domain, offset);
>> +}
> 
> This goes away to the core with GPIOLIB_IRQCHIP
> 
Okay, thanks!

>> +static void cygnus_gpio_irq_handler(unsigned int irq, struct irq_desc *desc)
>> +{
>> +       struct cygnus_gpio *cygnus_gpio;
>> +       struct irq_chip *chip = irq_desc_get_chip(desc);
>> +       int i, bit;
>> +
>> +       chained_irq_enter(chip, desc);
>> +
>> +       cygnus_gpio = irq_get_handler_data(irq);
>> +
>> +       /* go through the entire GPIO banks and handle all interrupts */
>> +       for (i = 0; i < cygnus_gpio->num_banks; i++) {
>> +               unsigned long val = cygnus_readl(cygnus_gpio,
>> +                               (i * GPIO_BANK_SIZE) +
>> +                               CYGNUS_GPIO_INT_MSTAT_OFFSET);
>> +
>> +               for_each_set_bit(bit, &val, NGPIOS_PER_BANK) {
>> +                       unsigned pin = NGPIOS_PER_BANK * i + bit;
>> +                       int child_irq =
>> +                               cygnus_gpio_to_irq(&cygnus_gpio->gc, pin);
>> +
>> +                       /*
>> +                        * Clear the interrupt before invoking the
>> +                        * handler, so we do not leave any window
>> +                        */
>> +                       cygnus_writel(cygnus_gpio, (i * GPIO_BANK_SIZE) +
>> +                               CYGNUS_GPIO_INT_CLR_OFFSET, BIT(bit));
>> +
>> +                       generic_handle_irq(child_irq);
>> +               }
>> +       }
>> +
>> +       chained_irq_exit(chip, desc);
>> +}
> 
> Looks good, but you will need to have the struct gpio_chip * as
> handler data to use GPIOLIB_IRQCHIP, so get from there to
> the struct cygnus_gpio something like:
> 
> struct gpio_chip *gc = irq_desc_get_handler_data(desc);
> struct cygnus_gpio *cyg = to_cygnus_gpio(gc);
> 
Okay thanks!

>> +static int cygnus_gpio_get(struct gpio_chip *gc, unsigned gpio)
>> +{
>> +       struct cygnus_gpio *cygnus_gpio = to_cygnus_gpio(gc);
>> +       unsigned int offset = CYGNUS_GPIO_REG(gpio,
>> +                       CYGNUS_GPIO_DATA_IN_OFFSET);
>> +       unsigned int shift = CYGNUS_GPIO_SHIFT(gpio);
>> +       u32 val;
>> +
>> +       val = cygnus_readl(cygnus_gpio, offset);
>> +       val = (val >> shift) & 1;
> 
> No, do this:
> 
> return !!(cygnus_readl(cygnus_gpio, offset) & BIT(shift));
> 
> Maybe rename the "shift" variable to "bit" or just use the macro
> directly in the readl().
> 
Will do!

>> +static int cygnus_gpio_irq_map(struct irq_domain *d, unsigned int irq,
>> +                              irq_hw_number_t hwirq)
>> +{
>> +       int ret;
>> +
>> +       ret = irq_set_chip_data(irq, d->host_data);
>> +       if (ret < 0)
>> +               return ret;
>> +       irq_set_lockdep_class(irq, &gpio_lock_class);
>> +       irq_set_chip_and_handler(irq, &cygnus_gpio_irq_chip,
>> +                       handle_simple_irq);
>> +       set_irq_flags(irq, IRQF_VALID);
>> +
>> +       return 0;
>> +}
>> +
>> +static void cygnus_gpio_irq_unmap(struct irq_domain *d, unsigned int irq)
>> +{
>> +       irq_set_chip_and_handler(irq, NULL, NULL);
>> +       irq_set_chip_data(irq, NULL);
>> +}
>> +
>> +static struct irq_domain_ops cygnus_irq_ops = {
>> +       .map = cygnus_gpio_irq_map,
>> +       .unmap = cygnus_gpio_irq_unmap,
>> +       .xlate = irq_domain_xlate_twocell,
>> +};
> 
> All this goes away with GPIOLIB_IRQCHIP (that is what is good about it).
> 
Great!

>> +#ifdef CONFIG_OF_GPIO
> 
> What, that should be defined all the time, you depend on it in
> Kconfig!
> 
Yes. Will get rid of this

>> +static void cygnus_gpio_set_pull(struct cygnus_gpio *cygnus_gpio,
>> +                                unsigned gpio, enum gpio_pull pull)
> (...)
>> +static void cygnus_gpio_set_strength(struct cygnus_gpio *cygnus_gpio,
>> +               unsigned gpio, enum gpio_drv_strength strength)
> (...)
>> +static int cygnus_gpio_of_xlate(struct gpio_chip *gc,
>> +               const struct of_phandle_args *gpiospec, u32 *flags)
> 
> NAK. This is pin control, put this in the pin control driver.
> 
> I guess the same that is part of this patch series.
> 
> (...)
Agreed.

>> +static int cygnus_gpio_probe(struct platform_device *pdev)
>> +{
>> +       struct device *dev = &pdev->dev;
>> +       struct resource *res;
>> +       struct cygnus_gpio *cygnus_gpio;
>> +       struct gpio_chip *gc;
>> +       u32 i, ngpios;
>> +       int ret;
>> +
>> +       cygnus_gpio = devm_kzalloc(dev, sizeof(*cygnus_gpio), GFP_KERNEL);
>> +       if (!cygnus_gpio)
>> +               return -ENOMEM;
>> +
>> +       cygnus_gpio->dev = dev;
>> +       platform_set_drvdata(pdev, cygnus_gpio);
>> +
>> +       if (of_property_read_u32(dev->of_node, "ngpios", &ngpios)) {
>> +               dev_err(&pdev->dev, "missing ngpios DT property\n");
>> +               return -ENODEV;
>> +       }
>> +       cygnus_gpio->num_banks = (ngpios + NGPIOS_PER_BANK - 1) /
>> +               NGPIOS_PER_BANK;
>> +
>> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +       cygnus_gpio->base = devm_ioremap_resource(dev, res);
>> +       if (IS_ERR(cygnus_gpio->base)) {
>> +               dev_err(&pdev->dev, "unable to map I/O memory\n");
>> +               return PTR_ERR(cygnus_gpio->base);
>> +       }
>> +
>> +       /*
>> +        * Only certain types of Cygnus GPIO interfaces have I/O control
>> +        * registers
>> +        */
>> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
>> +       if (res) {
>> +               cygnus_gpio->io_ctrl = devm_ioremap_resource(dev, res);
>> +               if (IS_ERR(cygnus_gpio->io_ctrl)) {
>> +                       dev_err(&pdev->dev, "unable to map I/O memory\n");
>> +                       return PTR_ERR(cygnus_gpio->io_ctrl);
>> +               }
>> +       }
> 
> This is a good indication that it's a separate piece of HW and should
> be a separate pin control driver.
> 
Okay.

>> +
>> +       spin_lock_init(&cygnus_gpio->lock);
>> +
>> +       gc = &cygnus_gpio->gc;
>> +       gc->base = -1;
>> +       gc->ngpio = ngpios;
>> +       gc->label = dev_name(dev);
>> +       gc->dev = dev;
>> +#ifdef CONFIG_OF_GPIO
> 
> You depend on this symbol.
> 
Will get rid of it.

>> +       gc->of_node = dev->of_node;
>> +       gc->of_gpio_n_cells = 2;
>> +       gc->of_xlate = cygnus_gpio_of_xlate;
>> +#endif
>> +       gc->direction_input = cygnus_gpio_direction_input;
>> +       gc->direction_output = cygnus_gpio_direction_output;
>> +       gc->set = cygnus_gpio_set;
>> +       gc->get = cygnus_gpio_get;
>> +       gc->to_irq = cygnus_gpio_to_irq;
>> +
>> +       ret = gpiochip_add(gc);
>> +       if (ret < 0) {
>> +               dev_err(&pdev->dev, "unable to add GPIO chip\n");
>> +               return ret;
>> +       }
>> +
>> +       /*
>> +        * Some of the GPIO interfaces do not have interrupt wired to the main
>> +        * processor
>> +        */
>> +       cygnus_gpio->irq = platform_get_irq(pdev, 0);
>> +       if (cygnus_gpio->irq < 0) {
>> +               ret = cygnus_gpio->irq;
>> +               if (ret == -EPROBE_DEFER)
>> +                       goto err_rm_gpiochip;
>> +
>> +               dev_info(&pdev->dev, "no interrupt hook\n");
>> +       }
> 
> From here:
> 
>> +       cygnus_gpio->irq_domain = irq_domain_add_linear(dev->of_node,
>> +                       gc->ngpio, &cygnus_irq_ops, cygnus_gpio);
>> +       if (!cygnus_gpio->irq_domain) {
>> +               dev_err(&pdev->dev, "unable to allocate IRQ domain\n");
>> +               ret = -ENXIO;
>> +               goto err_rm_gpiochip;
>> +       }
>> +
>> +       for (i = 0; i < gc->ngpio; i++) {
>> +               int irq = irq_create_mapping(cygnus_gpio->irq_domain, i);
>> +
>> +               irq_set_lockdep_class(irq, &gpio_lock_class);
>> +               irq_set_chip_data(irq, cygnus_gpio);
>> +               irq_set_chip_and_handler(irq, &cygnus_gpio_irq_chip,
>> +                               handle_simple_irq);
>> +               set_irq_flags(irq, IRQF_VALID);
>> +       }
>> +
>> +       irq_set_chained_handler(cygnus_gpio->irq, cygnus_gpio_irq_handler);
>> +       irq_set_handler_data(cygnus_gpio->irq, cygnus_gpio);
> 
> To here, replace with a single call to
> gpiochip_set_chained_irqchip(chip *, irq_chip *, irq, handler)...
This is excellent! Thanks!

> 
> Look at other drivers using GPIOLIB_IRQCHIP for inspiration.
> 
> Yours,
> Linus Walleij
> 
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Linus Walleij Jan. 16, 2015, 10:14 a.m. UTC | #3
On Tue, Jan 13, 2015 at 6:05 PM, Ray Jui <rjui@broadcom.com> wrote:
> On 1/13/2015 12:53 AM, Linus Walleij wrote:
>> On Tue, Dec 16, 2014 at 3:18 AM, Ray Jui <rjui@broadcom.com> wrote:
>>
>>> +/* drive strength control for ASIU GPIO */
>>> +#define CYGNUS_GPIO_ASIU_DRV0_CTRL_OFFSET 0x58
>>> +
>>> +/* drive strength control for CCM GPIO */
>>> +#define CYGNUS_GPIO_CCM_DRV0_CTRL_OFFSET  0x00
>>
>> This stuff (drive strength) is pin control, pin config.
>> It does not belong in a pure GPIO driver. If you're
>> making a combined pin control + GPIO driver, it
>> shall be put in drivers/pinctrl/*
>>
> Okay, I have some questions here. Are you suggesting me to register this
> driver to both the pinctrl subsystem and gpiolib and move it to under
> drivers/pinctrl/*?

Either you can have a combined driver in drivers/pinctrl/*
which has one probe() function calling pinctrl_register(),
gpiochip_add(), gpiochip_add_pin_range(), having the gpio
parts call into the pin control backend with
pinctrl_request_gpio(), pinctrl_free_gpio(),
pinctrl_gpio_direction_input(), pinctrl_gpio_direction_output().

Or you can split it in one driver in drivers/pinctrl/*
dealing with just the pin control stuff, and another driver
in drivers/gpio/* dealing with the GPIO stuff, each with one
probe() function.

If they are using the same register range, the first approach
is probably most intuitive. If the pin control and GPIO parts
are separated in different register ranges, probably the
second approach is the best.

> Or Are you suggesting me to combine this driver with the other Cygnus
> pinctrl driver (which only supports pinmux)?

Depends on which hardware block the pin control-like
registers belongs in. See per above.

> Note in Cygnus, all pinmux logic is done in the pinmux block. And there
> are 3 GPIO controllers, that handle GPIO, drive strength of the GPIO
> pins, internal pull up/down of the GPIO pins, which are handled in this
> driver. So this driver is generic to all 3 GPIO controllers, as you can
> see from the device tree bindings, there are 3 nodes.
>
> Therefore, I think it makes sense to have one pinmux driver that handles
> the pinmux block, and one generic pinctrl + gpio driver that handles
> functions supported by all 3 GPIO controllers. Does this make sense to you?

Yep.

Some hardware designs put the software-controlled biasing
resistors in the GPIO block electronically connected to the actual
pins, so that e.g. the biasing will be available if some MMC or
whatever is using the same pins in another muxing. In such
situations it's quite evident that they need to be a combined
GPIO and pin controller.

I have some regrets that bolting a second pin controller to the
GPIO chip make things a bit complex but it's a price we have
to pay for getting some kind of generic interface.

Yours,
Linus Walleij
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Ray Jui Jan. 17, 2015, 12:11 a.m. UTC | #4
On 1/16/2015 2:14 AM, Linus Walleij wrote:
> On Tue, Jan 13, 2015 at 6:05 PM, Ray Jui <rjui@broadcom.com> wrote:
>> On 1/13/2015 12:53 AM, Linus Walleij wrote:
>>> On Tue, Dec 16, 2014 at 3:18 AM, Ray Jui <rjui@broadcom.com> wrote:
>>>
>>>> +/* drive strength control for ASIU GPIO */
>>>> +#define CYGNUS_GPIO_ASIU_DRV0_CTRL_OFFSET 0x58
>>>> +
>>>> +/* drive strength control for CCM GPIO */
>>>> +#define CYGNUS_GPIO_CCM_DRV0_CTRL_OFFSET  0x00
>>>
>>> This stuff (drive strength) is pin control, pin config.
>>> It does not belong in a pure GPIO driver. If you're
>>> making a combined pin control + GPIO driver, it
>>> shall be put in drivers/pinctrl/*
>>>
>> Okay, I have some questions here. Are you suggesting me to register this
>> driver to both the pinctrl subsystem and gpiolib and move it to under
>> drivers/pinctrl/*?
> 
> Either you can have a combined driver in drivers/pinctrl/*
> which has one probe() function calling pinctrl_register(),
> gpiochip_add(), gpiochip_add_pin_range(), having the gpio
> parts call into the pin control backend with
> pinctrl_request_gpio(), pinctrl_free_gpio(),
> pinctrl_gpio_direction_input(), pinctrl_gpio_direction_output().
> 
> Or you can split it in one driver in drivers/pinctrl/*
> dealing with just the pin control stuff, and another driver
> in drivers/gpio/* dealing with the GPIO stuff, each with one
> probe() function.
> 
> If they are using the same register range, the first approach
> is probably most intuitive. If the pin control and GPIO parts
> are separated in different register ranges, probably the
> second approach is the best.
> 
>> Or Are you suggesting me to combine this driver with the other Cygnus
>> pinctrl driver (which only supports pinmux)?
> 
> Depends on which hardware block the pin control-like
> registers belongs in. See per above.
> 
>> Note in Cygnus, all pinmux logic is done in the pinmux block. And there
>> are 3 GPIO controllers, that handle GPIO, drive strength of the GPIO
>> pins, internal pull up/down of the GPIO pins, which are handled in this
>> driver. So this driver is generic to all 3 GPIO controllers, as you can
>> see from the device tree bindings, there are 3 nodes.
>>
>> Therefore, I think it makes sense to have one pinmux driver that handles
>> the pinmux block, and one generic pinctrl + gpio driver that handles
>> functions supported by all 3 GPIO controllers. Does this make sense to you?
> 
> Yep.
> 
> Some hardware designs put the software-controlled biasing
> resistors in the GPIO block electronically connected to the actual
> pins, so that e.g. the biasing will be available if some MMC or
> whatever is using the same pins in another muxing. In such
> situations it's quite evident that they need to be a combined
> GPIO and pin controller.
> 
> I have some regrets that bolting a second pin controller to the
> GPIO chip make things a bit complex but it's a price we have
> to pay for getting some kind of generic interface.
> 
> Yours,
> Linus Walleij
> 
Okay. In summary, I think both of us think the following approach makes
sense in my situation:
- leave pinmux in pinctrl-bcm-cygnus.c
- leave pinctrl + gpio in pinctrl-bcm-cygnus-gpio.c under drivers/pinctrl/*

But by thinking about this more, I thought this would create duplicated
pinctrl descriptors in our system, one from the pinmux driver, and the
other from this pinctrl+gpio driver. That is probably undesirable?

By reviewing various drivers in the pinctrl directory, I found what
pinctrl-u300.c and pinctrl-coh901.c does seems to serve as a good model
for me to follow:
- pinctrl-u300.c is the pinmux driver
- pinctrl-coh901.c is the gpio+pinctrl driver

The GPIO pinctrl logic is in the coh901 block, so pinctrl-coh901.c
exposed two public functions u300_gpio_config_get, u300_gpio_config_set
that pinctrl-u300.c can use. The u300 populates all pinmux/pinctrl
related functions into the subsystem. This way there's only one pinctrl
descriptor, populated through pinctrl-u300.c.

Does that model make more sense to you?

Thanks,

Ray
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Linus Walleij Jan. 20, 2015, 9:53 a.m. UTC | #5
On Sat, Jan 17, 2015 at 1:11 AM, Ray Jui <rjui@broadcom.com> wrote:
> On 1/16/2015 2:14 AM, Linus Walleij wrote:

>> Some hardware designs put the software-controlled biasing
>> resistors in the GPIO block electronically connected to the actual
>> pins, so that e.g. the biasing will be available if some MMC or
>> whatever is using the same pins in another muxing. In such
>> situations it's quite evident that they need to be a combined
>> GPIO and pin controller.
>>
>> I have some regrets that bolting a second pin controller to the
>> GPIO chip make things a bit complex but it's a price we have
>> to pay for getting some kind of generic interface.
>
> Okay. In summary, I think both of us think the following approach makes
> sense in my situation:
> - leave pinmux in pinctrl-bcm-cygnus.c
> - leave pinctrl + gpio in pinctrl-bcm-cygnus-gpio.c under drivers/pinctrl/*
>
> But by thinking about this more, I thought this would create duplicated
> pinctrl descriptors in our system, one from the pinmux driver, and the
> other from this pinctrl+gpio driver. That is probably undesirable?

No, there are several systems with multiple pin controllers and the
framework easily handles multiple pin controllers in the same
system just as well as we handle multiple GPIO chips.

> By reviewing various drivers in the pinctrl directory, I found what
> pinctrl-u300.c and pinctrl-coh901.c does seems to serve as a good model
> for me to follow:
> - pinctrl-u300.c is the pinmux driver
> - pinctrl-coh901.c is the gpio+pinctrl driver

Yeah, I don't know if the separation between them is as beautiful
as it should be. I used it when developing the pin control
subsystem.

> The GPIO pinctrl logic is in the coh901 block, so pinctrl-coh901.c
> exposed two public functions u300_gpio_config_get, u300_gpio_config_set
> that pinctrl-u300.c can use. The u300 populates all pinmux/pinctrl
> related functions into the subsystem. This way there's only one pinctrl
> descriptor, populated through pinctrl-u300.c.
>
> Does that model make more sense to you?

Yeah I wrote it myself so I'm maybe blind for any dumbness in
the code. But I think it's kind of elegant. But it is not using the
generic pinctrl device tree bindings so it's kind of oldstyle and
bloated in that sense.

Yours,
Linus Walleij
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Ray Jui Jan. 20, 2015, 7:17 p.m. UTC | #6
On 1/20/2015 1:53 AM, Linus Walleij wrote:
> On Sat, Jan 17, 2015 at 1:11 AM, Ray Jui <rjui@broadcom.com> wrote:
>> On 1/16/2015 2:14 AM, Linus Walleij wrote:
> 
>>> Some hardware designs put the software-controlled biasing
>>> resistors in the GPIO block electronically connected to the actual
>>> pins, so that e.g. the biasing will be available if some MMC or
>>> whatever is using the same pins in another muxing. In such
>>> situations it's quite evident that they need to be a combined
>>> GPIO and pin controller.
>>>
>>> I have some regrets that bolting a second pin controller to the
>>> GPIO chip make things a bit complex but it's a price we have
>>> to pay for getting some kind of generic interface.
>>
>> Okay. In summary, I think both of us think the following approach makes
>> sense in my situation:
>> - leave pinmux in pinctrl-bcm-cygnus.c
>> - leave pinctrl + gpio in pinctrl-bcm-cygnus-gpio.c under drivers/pinctrl/*
>>
>> But by thinking about this more, I thought this would create duplicated
>> pinctrl descriptors in our system, one from the pinmux driver, and the
>> other from this pinctrl+gpio driver. That is probably undesirable?
> 
> No, there are several systems with multiple pin controllers and the
> framework easily handles multiple pin controllers in the same
> system just as well as we handle multiple GPIO chips.
> 
>> By reviewing various drivers in the pinctrl directory, I found what
>> pinctrl-u300.c and pinctrl-coh901.c does seems to serve as a good model
>> for me to follow:
>> - pinctrl-u300.c is the pinmux driver
>> - pinctrl-coh901.c is the gpio+pinctrl driver
> 
> Yeah, I don't know if the separation between them is as beautiful
> as it should be. I used it when developing the pin control
> subsystem.
> 
>> The GPIO pinctrl logic is in the coh901 block, so pinctrl-coh901.c
>> exposed two public functions u300_gpio_config_get, u300_gpio_config_set
>> that pinctrl-u300.c can use. The u300 populates all pinmux/pinctrl
>> related functions into the subsystem. This way there's only one pinctrl
>> descriptor, populated through pinctrl-u300.c.
>>
>> Does that model make more sense to you?
> 
> Yeah I wrote it myself so I'm maybe blind for any dumbness in
> the code. But I think it's kind of elegant. But it is not using the
> generic pinctrl device tree bindings so it's kind of oldstyle and
> bloated in that sense.
> 
> Yours,
> Linus Walleij
> 
Okay. I think I have a pretty good idea of what you expect. Regarding
whether or not to keep pinctrl-bcm-cygnus.c and
pinctrl-bcm-cygnus-gpio.c completely independent with each other and
therefore have two pinctrl in the system, I'll play with it a bit more
and make a decision.

Thanks a lot for spending all these time explaining it to me. Really
appreciate it!
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Patch
diff mbox

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 633ec21..1790ffd 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -126,6 +126,18 @@  config GPIO_74XX_MMIO
 	    8 bits:	74244 (Input), 74273 (Output)
 	    16 bits:	741624 (Input), 7416374 (Output)
 
+config GPIO_BCM_CYGNUS
+	bool "Broadcom Cygnus GPIO support"
+	depends on ARCH_BCM_CYGNUS && OF_GPIO
+	default y
+	help
+	  Say yes here to turn on GPIO support for Broadcom Cygnus SoC
+
+	  The Broadcom Cygnus SoC has 3 GPIO controllers including the ASIU
+	  GPIO controller (ASIU), the chipCommonG GPIO controller (CCM), and
+	  the always-ON GPIO controller (CRMU). All 3 GPIO controllers are
+	  supported by this driver
+
 config GPIO_CLPS711X
 	tristate "CLPS711X GPIO support"
 	depends on ARCH_CLPS711X || COMPILE_TEST
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 81755f1..31eb7e0 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -19,6 +19,7 @@  obj-$(CONFIG_GPIO_ADP5520)	+= gpio-adp5520.o
 obj-$(CONFIG_GPIO_ADP5588)	+= gpio-adp5588.o
 obj-$(CONFIG_GPIO_AMD8111)	+= gpio-amd8111.o
 obj-$(CONFIG_GPIO_ARIZONA)	+= gpio-arizona.o
+obj-$(CONFIG_GPIO_BCM_CYGNUS)	+= gpio-bcm-cygnus.o
 obj-$(CONFIG_GPIO_BCM_KONA)	+= gpio-bcm-kona.o
 obj-$(CONFIG_GPIO_BT8XX)	+= gpio-bt8xx.o
 obj-$(CONFIG_GPIO_CLPS711X)	+= gpio-clps711x.o
diff --git a/drivers/gpio/gpio-bcm-cygnus.c b/drivers/gpio/gpio-bcm-cygnus.c
new file mode 100644
index 0000000..817bc9a
--- /dev/null
+++ b/drivers/gpio/gpio-bcm-cygnus.c
@@ -0,0 +1,607 @@ 
+/*
+ * Copyright (C) 2014 Broadcom Corporation
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/gpio.h>
+#include <linux/ioport.h>
+#include <linux/of_device.h>
+#include <linux/of_irq.h>
+#include <linux/irqchip/chained_irq.h>
+
+#define CYGNUS_GPIO_DATA_IN_OFFSET   0x00
+#define CYGNUS_GPIO_DATA_OUT_OFFSET  0x04
+#define CYGNUS_GPIO_OUT_EN_OFFSET    0x08
+#define CYGNUS_GPIO_IN_TYPE_OFFSET   0x0c
+#define CYGNUS_GPIO_INT_DE_OFFSET    0x10
+#define CYGNUS_GPIO_INT_EDGE_OFFSET  0x14
+#define CYGNUS_GPIO_INT_MSK_OFFSET   0x18
+#define CYGNUS_GPIO_INT_STAT_OFFSET  0x1c
+#define CYGNUS_GPIO_INT_MSTAT_OFFSET 0x20
+#define CYGNUS_GPIO_INT_CLR_OFFSET   0x24
+#define CYGNUS_GPIO_PAD_RES_OFFSET   0x34
+#define CYGNUS_GPIO_RES_EN_OFFSET    0x38
+
+/* drive strength control for ASIU GPIO */
+#define CYGNUS_GPIO_ASIU_DRV0_CTRL_OFFSET 0x58
+
+/* drive strength control for CCM GPIO */
+#define CYGNUS_GPIO_CCM_DRV0_CTRL_OFFSET  0x00
+
+#define GPIO_BANK_SIZE 0x200
+#define NGPIOS_PER_BANK 32
+#define GPIO_BANK(pin) ((pin) / NGPIOS_PER_BANK)
+
+#define CYGNUS_GPIO_REG(pin, reg) (GPIO_BANK(pin) * GPIO_BANK_SIZE + (reg))
+#define CYGNUS_GPIO_SHIFT(pin) ((pin) % NGPIOS_PER_BANK)
+
+#define GPIO_FLAG_BIT_MASK           0xffff
+#define GPIO_PULL_BIT_SHIFT          16
+#define GPIO_PULL_BIT_MASK           0x3
+
+#define GPIO_DRV_STRENGTH_BIT_SHIFT  20
+#define GPIO_DRV_STRENGTH_BITS       3
+#define GPIO_DRV_STRENGTH_BIT_MASK   ((1 << GPIO_DRV_STRENGTH_BITS) - 1)
+
+/*
+ * For GPIO internal pull up/down registers
+ */
+enum gpio_pull {
+	GPIO_PULL_NONE = 0,
+	GPIO_PULL_UP,
+	GPIO_PULL_DOWN,
+	GPIO_PULL_INVALID,
+};
+
+/*
+ * GPIO drive strength
+ */
+enum gpio_drv_strength {
+	GPIO_DRV_STRENGTH_2MA = 0,
+	GPIO_DRV_STRENGTH_4MA,
+	GPIO_DRV_STRENGTH_6MA,
+	GPIO_DRV_STRENGTH_8MA,
+	GPIO_DRV_STRENGTH_10MA,
+	GPIO_DRV_STRENGTH_12MA,
+	GPIO_DRV_STRENGTH_14MA,
+	GPIO_DRV_STRENGTH_16MA,
+	GPIO_DRV_STRENGTH_INVALID,
+};
+
+struct cygnus_gpio {
+	struct device *dev;
+	void __iomem *base;
+	void __iomem *io_ctrl;
+	spinlock_t lock;
+	struct gpio_chip gc;
+	unsigned num_banks;
+	int irq;
+	struct irq_domain *irq_domain;
+};
+
+static struct cygnus_gpio *to_cygnus_gpio(struct gpio_chip *gc)
+{
+	return container_of(gc, struct cygnus_gpio, gc);
+}
+
+static u32 cygnus_readl(struct cygnus_gpio *cygnus_gpio, unsigned int offset)
+{
+	return readl(cygnus_gpio->base + offset);
+}
+
+static void cygnus_writel(struct cygnus_gpio *cygnus_gpio,
+			  unsigned int offset, u32 val)
+{
+	writel(val, cygnus_gpio->base + offset);
+}
+
+/**
+ *  cygnus_set_bit - set or clear one bit (corresponding to the GPIO pin) in a
+ *  Cygnus GPIO register
+ *
+ *  @cygnus_gpio: Cygnus GPIO device
+ *  @reg: register offset
+ *  @gpio: GPIO pin
+ *  @set: set or clear. 1 - set; 0 -clear
+ */
+static void cygnus_set_bit(struct cygnus_gpio *cygnus_gpio,
+			   unsigned int reg, unsigned gpio, int set)
+{
+	unsigned int offset = CYGNUS_GPIO_REG(gpio, reg);
+	unsigned int shift = CYGNUS_GPIO_SHIFT(gpio);
+	u32 val;
+
+	val = cygnus_readl(cygnus_gpio, offset);
+	if (set)
+		val |= BIT(shift);
+	else
+		val &= ~BIT(shift);
+	cygnus_writel(cygnus_gpio, offset, val);
+}
+
+static int cygnus_gpio_to_irq(struct gpio_chip *gc, unsigned offset)
+{
+	struct cygnus_gpio *cygnus_gpio = to_cygnus_gpio(gc);
+
+	return irq_find_mapping(cygnus_gpio->irq_domain, offset);
+}
+
+static void cygnus_gpio_irq_handler(unsigned int irq, struct irq_desc *desc)
+{
+	struct cygnus_gpio *cygnus_gpio;
+	struct irq_chip *chip = irq_desc_get_chip(desc);
+	int i, bit;
+
+	chained_irq_enter(chip, desc);
+
+	cygnus_gpio = irq_get_handler_data(irq);
+
+	/* go through the entire GPIO banks and handle all interrupts */
+	for (i = 0; i < cygnus_gpio->num_banks; i++) {
+		unsigned long val = cygnus_readl(cygnus_gpio,
+				(i * GPIO_BANK_SIZE) +
+				CYGNUS_GPIO_INT_MSTAT_OFFSET);
+
+		for_each_set_bit(bit, &val, NGPIOS_PER_BANK) {
+			unsigned pin = NGPIOS_PER_BANK * i + bit;
+			int child_irq =
+				cygnus_gpio_to_irq(&cygnus_gpio->gc, pin);
+
+			/*
+			 * Clear the interrupt before invoking the
+			 * handler, so we do not leave any window
+			 */
+			cygnus_writel(cygnus_gpio, (i * GPIO_BANK_SIZE) +
+				CYGNUS_GPIO_INT_CLR_OFFSET, BIT(bit));
+
+			generic_handle_irq(child_irq);
+		}
+	}
+
+	chained_irq_exit(chip, desc);
+}
+
+
+static void cygnus_gpio_irq_ack(struct irq_data *d)
+{
+	struct cygnus_gpio *cygnus_gpio = irq_data_get_irq_chip_data(d);
+	unsigned gpio = d->hwirq;
+	unsigned int offset = CYGNUS_GPIO_REG(gpio,
+			CYGNUS_GPIO_INT_CLR_OFFSET);
+	unsigned int shift = CYGNUS_GPIO_SHIFT(gpio);
+	u32 val = BIT(shift);
+
+	cygnus_writel(cygnus_gpio, offset, val);
+}
+
+/**
+ *  cygnus_gpio_irq_set_mask - mask/unmask a GPIO interrupt
+ *
+ *  @d: IRQ chip data
+ *  @mask: mask/unmask GPIO interrupt. 0 - mask (disable); 1 - unmask (enable)
+ */
+static void cygnus_gpio_irq_set_mask(struct irq_data *d, int mask)
+{
+	struct cygnus_gpio *cygnus_gpio = irq_data_get_irq_chip_data(d);
+	unsigned gpio = d->hwirq;
+
+	cygnus_set_bit(cygnus_gpio, CYGNUS_GPIO_INT_MSK_OFFSET, gpio, mask);
+}
+
+static void cygnus_gpio_irq_mask(struct irq_data *d)
+{
+	struct cygnus_gpio *cygnus_gpio = irq_data_get_irq_chip_data(d);
+	unsigned long flags;
+
+	spin_lock_irqsave(&cygnus_gpio->lock, flags);
+	cygnus_gpio_irq_set_mask(d, 0);
+	spin_unlock_irqrestore(&cygnus_gpio->lock, flags);
+}
+
+static void cygnus_gpio_irq_unmask(struct irq_data *d)
+{
+	struct cygnus_gpio *cygnus_gpio = irq_data_get_irq_chip_data(d);
+	unsigned long flags;
+
+	spin_lock_irqsave(&cygnus_gpio->lock, flags);
+	cygnus_gpio_irq_set_mask(d, 1);
+	spin_unlock_irqrestore(&cygnus_gpio->lock, flags);
+}
+
+static int cygnus_gpio_irq_set_type(struct irq_data *d, unsigned int type)
+{
+	struct cygnus_gpio *cygnus_gpio = irq_data_get_irq_chip_data(d);
+	unsigned gpio = d->hwirq;
+	int int_type = 0, dual_edge = 0, edge_lvl = 0;
+	unsigned long flags;
+
+	switch (type & IRQ_TYPE_SENSE_MASK) {
+	case IRQ_TYPE_EDGE_RISING:
+		edge_lvl = 1;
+		break;
+
+	case IRQ_TYPE_EDGE_FALLING:
+		break;
+
+	case IRQ_TYPE_EDGE_BOTH:
+		dual_edge = 1;
+		break;
+
+	case IRQ_TYPE_LEVEL_HIGH:
+		int_type = 1;
+		edge_lvl = 1;
+		break;
+
+	case IRQ_TYPE_LEVEL_LOW:
+		int_type = 1;
+		break;
+
+	default:
+		dev_err(cygnus_gpio->dev, "invalid GPIO IRQ type 0x%x\n",
+				type);
+		return -EINVAL;
+	}
+
+	spin_lock_irqsave(&cygnus_gpio->lock, flags);
+	cygnus_set_bit(cygnus_gpio, CYGNUS_GPIO_IN_TYPE_OFFSET, gpio,
+			int_type);
+	cygnus_set_bit(cygnus_gpio, CYGNUS_GPIO_INT_DE_OFFSET, gpio,
+			dual_edge);
+	cygnus_set_bit(cygnus_gpio, CYGNUS_GPIO_INT_EDGE_OFFSET, gpio,
+			edge_lvl);
+	spin_unlock_irqrestore(&cygnus_gpio->lock, flags);
+
+	dev_dbg(cygnus_gpio->dev,
+		"gpio:%u set int_type:%d dual_edge:%d edge_lvl:%d\n",
+		gpio, int_type, dual_edge, edge_lvl);
+
+	return 0;
+}
+
+static struct irq_chip cygnus_gpio_irq_chip = {
+	.name = "bcm-cygnus-gpio",
+	.irq_ack = cygnus_gpio_irq_ack,
+	.irq_mask = cygnus_gpio_irq_mask,
+	.irq_unmask = cygnus_gpio_irq_unmask,
+	.irq_set_type = cygnus_gpio_irq_set_type,
+};
+
+static int cygnus_gpio_direction_input(struct gpio_chip *gc, unsigned gpio)
+{
+	struct cygnus_gpio *cygnus_gpio = to_cygnus_gpio(gc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&cygnus_gpio->lock, flags);
+	cygnus_set_bit(cygnus_gpio, CYGNUS_GPIO_OUT_EN_OFFSET, gpio, 0);
+	spin_unlock_irqrestore(&cygnus_gpio->lock, flags);
+
+	dev_dbg(cygnus_gpio->dev, "gpio:%u set input\n", gpio);
+
+	return 0;
+}
+
+static int cygnus_gpio_direction_output(struct gpio_chip *gc,
+		unsigned gpio, int value)
+{
+	struct cygnus_gpio *cygnus_gpio = to_cygnus_gpio(gc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&cygnus_gpio->lock, flags);
+	cygnus_set_bit(cygnus_gpio, CYGNUS_GPIO_OUT_EN_OFFSET, gpio, 1);
+	cygnus_set_bit(cygnus_gpio, CYGNUS_GPIO_DATA_OUT_OFFSET, gpio, value);
+	spin_unlock_irqrestore(&cygnus_gpio->lock, flags);
+
+	dev_dbg(cygnus_gpio->dev, "gpio:%u set output, value:%d\n",
+			gpio, value);
+
+	return 0;
+}
+
+static void cygnus_gpio_set(struct gpio_chip *gc, unsigned gpio,
+		int value)
+{
+	struct cygnus_gpio *cygnus_gpio = to_cygnus_gpio(gc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&cygnus_gpio->lock, flags);
+	cygnus_set_bit(cygnus_gpio, CYGNUS_GPIO_DATA_OUT_OFFSET, gpio, value);
+	spin_unlock_irqrestore(&cygnus_gpio->lock, flags);
+
+	dev_dbg(cygnus_gpio->dev, "gpio:%u set, value:%d\n", gpio, value);
+}
+
+static int cygnus_gpio_get(struct gpio_chip *gc, unsigned gpio)
+{
+	struct cygnus_gpio *cygnus_gpio = to_cygnus_gpio(gc);
+	unsigned int offset = CYGNUS_GPIO_REG(gpio,
+			CYGNUS_GPIO_DATA_IN_OFFSET);
+	unsigned int shift = CYGNUS_GPIO_SHIFT(gpio);
+	u32 val;
+
+	val = cygnus_readl(cygnus_gpio, offset);
+	val = (val >> shift) & 1;
+
+	dev_dbg(cygnus_gpio->dev, "gpio:%u get, value:%d\n", gpio, val);
+
+	return val;
+}
+
+static struct lock_class_key gpio_lock_class;
+
+static int cygnus_gpio_irq_map(struct irq_domain *d, unsigned int irq,
+			       irq_hw_number_t hwirq)
+{
+	int ret;
+
+	ret = irq_set_chip_data(irq, d->host_data);
+	if (ret < 0)
+		return ret;
+	irq_set_lockdep_class(irq, &gpio_lock_class);
+	irq_set_chip_and_handler(irq, &cygnus_gpio_irq_chip,
+			handle_simple_irq);
+	set_irq_flags(irq, IRQF_VALID);
+
+	return 0;
+}
+
+static void cygnus_gpio_irq_unmap(struct irq_domain *d, unsigned int irq)
+{
+	irq_set_chip_and_handler(irq, NULL, NULL);
+	irq_set_chip_data(irq, NULL);
+}
+
+static struct irq_domain_ops cygnus_irq_ops = {
+	.map = cygnus_gpio_irq_map,
+	.unmap = cygnus_gpio_irq_unmap,
+	.xlate = irq_domain_xlate_twocell,
+};
+
+#ifdef CONFIG_OF_GPIO
+static void cygnus_gpio_set_pull(struct cygnus_gpio *cygnus_gpio,
+				 unsigned gpio, enum gpio_pull pull)
+{
+	int pullup;
+	unsigned long flags;
+
+	switch (pull) {
+	case GPIO_PULL_UP:
+		pullup = 1;
+		break;
+	case GPIO_PULL_DOWN:
+		pullup = 0;
+		break;
+	case GPIO_PULL_NONE:
+	case GPIO_PULL_INVALID:
+	default:
+		return;
+	}
+
+	spin_lock_irqsave(&cygnus_gpio->lock, flags);
+	/* set pull up/down */
+	cygnus_set_bit(cygnus_gpio, CYGNUS_GPIO_PAD_RES_OFFSET, gpio, pullup);
+	/* enable pad */
+	cygnus_set_bit(cygnus_gpio, CYGNUS_GPIO_RES_EN_OFFSET, gpio, 1);
+	spin_unlock_irqrestore(&cygnus_gpio->lock, flags);
+
+	dev_dbg(cygnus_gpio->dev, "gpio:%u set pullup:%d\n", gpio, pullup);
+}
+
+static void cygnus_gpio_set_strength(struct cygnus_gpio *cygnus_gpio,
+		unsigned gpio, enum gpio_drv_strength strength)
+{
+	struct device *dev = cygnus_gpio->dev;
+	void __iomem *base;
+	unsigned int i, offset, shift;
+	u32 val;
+	unsigned long flags;
+
+	/* some GPIO controllers do not support drive strength configuration */
+	if (of_find_property(dev->of_node, "no-drv-strength", NULL))
+		return;
+
+	/*
+	 * Some GPIO controllers use a different register block for drive
+	 * strength control
+	 */
+	if (cygnus_gpio->io_ctrl) {
+		base = cygnus_gpio->io_ctrl;
+		offset = CYGNUS_GPIO_CCM_DRV0_CTRL_OFFSET;
+	} else {
+		base = cygnus_gpio->base;
+		offset = CYGNUS_GPIO_REG(gpio,
+				CYGNUS_GPIO_ASIU_DRV0_CTRL_OFFSET);
+	}
+
+	shift = CYGNUS_GPIO_SHIFT(gpio);
+
+	spin_lock_irqsave(&cygnus_gpio->lock, flags);
+
+	for (i = 0; i < GPIO_DRV_STRENGTH_BITS; i++) {
+		val = readl(base + offset);
+		val &= ~BIT(shift);
+		val |= ((strength >> i) & 0x1) << shift;
+		writel(val, base + offset);
+		offset += 4;
+	}
+
+	spin_unlock_irqrestore(&cygnus_gpio->lock, flags);
+
+	dev_dbg(cygnus_gpio->dev,
+			"gpio:%u set drive strength:%d\n", gpio, strength);
+}
+
+static int cygnus_gpio_of_xlate(struct gpio_chip *gc,
+		const struct of_phandle_args *gpiospec, u32 *flags)
+{
+	struct cygnus_gpio *cygnus_gpio = to_cygnus_gpio(gc);
+	enum gpio_pull pull;
+	enum gpio_drv_strength strength;
+
+	if (gc->of_gpio_n_cells < 2)
+		return -EINVAL;
+
+	if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
+		return -EINVAL;
+
+	if (gpiospec->args[0] >= gc->ngpio)
+		return -EINVAL;
+
+	pull = (gpiospec->args[1] >> GPIO_PULL_BIT_SHIFT) & GPIO_PULL_BIT_MASK;
+	if (WARN_ON(pull >= GPIO_PULL_INVALID))
+		return -EINVAL;
+
+	strength = (gpiospec->args[1] >> GPIO_DRV_STRENGTH_BIT_SHIFT) &
+		GPIO_DRV_STRENGTH_BIT_MASK;
+
+	if (flags)
+		*flags = gpiospec->args[1] & GPIO_FLAG_BIT_MASK;
+
+	cygnus_gpio_set_pull(cygnus_gpio, gpiospec->args[0], pull);
+	cygnus_gpio_set_strength(cygnus_gpio, gpiospec->args[0], strength);
+
+	return gpiospec->args[0];
+}
+#endif
+
+static const struct of_device_id cygnus_gpio_of_match[] = {
+	{ .compatible = "brcm,cygnus-gpio" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, cygnus_gpio_of_match);
+
+static int cygnus_gpio_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	struct cygnus_gpio *cygnus_gpio;
+	struct gpio_chip *gc;
+	u32 i, ngpios;
+	int ret;
+
+	cygnus_gpio = devm_kzalloc(dev, sizeof(*cygnus_gpio), GFP_KERNEL);
+	if (!cygnus_gpio)
+		return -ENOMEM;
+
+	cygnus_gpio->dev = dev;
+	platform_set_drvdata(pdev, cygnus_gpio);
+
+	if (of_property_read_u32(dev->of_node, "ngpios", &ngpios)) {
+		dev_err(&pdev->dev, "missing ngpios DT property\n");
+		return -ENODEV;
+	}
+	cygnus_gpio->num_banks = (ngpios + NGPIOS_PER_BANK - 1) /
+		NGPIOS_PER_BANK;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	cygnus_gpio->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(cygnus_gpio->base)) {
+		dev_err(&pdev->dev, "unable to map I/O memory\n");
+		return PTR_ERR(cygnus_gpio->base);
+	}
+
+	/*
+	 * Only certain types of Cygnus GPIO interfaces have I/O control
+	 * registers
+	 */
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	if (res) {
+		cygnus_gpio->io_ctrl = devm_ioremap_resource(dev, res);
+		if (IS_ERR(cygnus_gpio->io_ctrl)) {
+			dev_err(&pdev->dev, "unable to map I/O memory\n");
+			return PTR_ERR(cygnus_gpio->io_ctrl);
+		}
+	}
+
+	spin_lock_init(&cygnus_gpio->lock);
+
+	gc = &cygnus_gpio->gc;
+	gc->base = -1;
+	gc->ngpio = ngpios;
+	gc->label = dev_name(dev);
+	gc->dev = dev;
+#ifdef CONFIG_OF_GPIO
+	gc->of_node = dev->of_node;
+	gc->of_gpio_n_cells = 2;
+	gc->of_xlate = cygnus_gpio_of_xlate;
+#endif
+	gc->direction_input = cygnus_gpio_direction_input;
+	gc->direction_output = cygnus_gpio_direction_output;
+	gc->set = cygnus_gpio_set;
+	gc->get = cygnus_gpio_get;
+	gc->to_irq = cygnus_gpio_to_irq;
+
+	ret = gpiochip_add(gc);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "unable to add GPIO chip\n");
+		return ret;
+	}
+
+	/*
+	 * Some of the GPIO interfaces do not have interrupt wired to the main
+	 * processor
+	 */
+	cygnus_gpio->irq = platform_get_irq(pdev, 0);
+	if (cygnus_gpio->irq < 0) {
+		ret = cygnus_gpio->irq;
+		if (ret == -EPROBE_DEFER)
+			goto err_rm_gpiochip;
+
+		dev_info(&pdev->dev, "no interrupt hook\n");
+	}
+
+	cygnus_gpio->irq_domain = irq_domain_add_linear(dev->of_node,
+			gc->ngpio, &cygnus_irq_ops, cygnus_gpio);
+	if (!cygnus_gpio->irq_domain) {
+		dev_err(&pdev->dev, "unable to allocate IRQ domain\n");
+		ret = -ENXIO;
+		goto err_rm_gpiochip;
+	}
+
+	for (i = 0; i < gc->ngpio; i++) {
+		int irq = irq_create_mapping(cygnus_gpio->irq_domain, i);
+
+		irq_set_lockdep_class(irq, &gpio_lock_class);
+		irq_set_chip_data(irq, cygnus_gpio);
+		irq_set_chip_and_handler(irq, &cygnus_gpio_irq_chip,
+				handle_simple_irq);
+		set_irq_flags(irq, IRQF_VALID);
+	}
+
+	irq_set_chained_handler(cygnus_gpio->irq, cygnus_gpio_irq_handler);
+	irq_set_handler_data(cygnus_gpio->irq, cygnus_gpio);
+
+	return 0;
+
+err_rm_gpiochip:
+	gpiochip_remove(gc);
+	return ret;
+}
+
+static struct platform_driver cygnus_gpio_driver = {
+	.driver = {
+		.name = "bcm-cygnus-gpio",
+		.owner = THIS_MODULE,
+		.of_match_table = cygnus_gpio_of_match,
+	},
+	.probe = cygnus_gpio_probe,
+};
+
+module_platform_driver(cygnus_gpio_driver);
+
+MODULE_AUTHOR("Ray Jui <rjui@broadcom.com>");
+MODULE_DESCRIPTION("Broadcom Cygnus GPIO Driver");
+MODULE_LICENSE("GPL v2");