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Message-Id: <20090609140239.260428eb.akpm@linux-foundation.org>
Date: Tue, 9 Jun 2009 14:02:39 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Baruch Siach <baruch@...s.co.il>
Cc: linux-kernel@...r.kernel.org, dbrownell@...rs.sourceforge.net,
linux-arm-kernel@...ts.arm.linux.org.uk, linux@....linux.org.uk,
baruch@...s.co.il
Subject: Re: [PATCH v4] gpio: driver for PrimeCell PL061 GPIO controller
On Sun, 7 Jun 2009 21:38:55 +0300
Baruch Siach <baruch@...s.co.il> wrote:
> This is a driver for the ARM PrimeCell PL061 GPIO AMBA peripheral. The driver
> is implemented using the gpiolib framework.
>
> This driver also includes support for the use of the PL061 as an interrupt
> controller (secondary).
>
> Signed-off-by: Baruch Siach <baruch@...s.co.il>
> ---
> Changes in v4:
> - Depend on CONFIG_ARM_AMBA
> - Do not request the gpio for IRQ automatically, just warn if it's not
> requested
> - Remove SZ_4K
> - Iterate through a linked list find the source of interrupt when
> multiple PL061s are connected to the same IRQ trigger
> - Move hardware register defines into the .c file
I generated an incremental diff so that we can see what you did.
> drivers/gpio/Kconfig | 1
> drivers/gpio/pl061.c | 92 ++++++++++++++++-------------------
> include/linux/amba/pl061.h | 19 +++----
> 3 files changed, 54 insertions(+), 58 deletions(-)
>
> diff -puN drivers/gpio/Kconfig~gpio-driver-for-primecell-pl061-gpio-controller-v4 drivers/gpio/Kconfig
> --- a/drivers/gpio/Kconfig~gpio-driver-for-primecell-pl061-gpio-controller-v4
> +++ a/drivers/gpio/Kconfig
> @@ -69,6 +69,7 @@ comment "Memory mapped GPIO expanders:"
>
> config GPIO_PL061
> bool "PrimeCell PL061 GPIO support"
> + depends on ARM_AMBA
> help
> Say yes here to support the PrimeCell PL061 GPIO device
>
> diff -puN drivers/gpio/pl061.c~gpio-driver-for-primecell-pl061-gpio-controller-v4 drivers/gpio/pl061.c
> --- a/drivers/gpio/pl061.c~gpio-driver-for-primecell-pl061-gpio-controller-v4
> +++ a/drivers/gpio/pl061.c
> @@ -14,6 +14,7 @@
> #include <linux/spinlock.h>
> #include <linux/errno.h>
> #include <linux/module.h>
> +#include <linux/list.h>
> #include <linux/io.h>
> #include <linux/ioport.h>
> #include <linux/irq.h>
> @@ -24,9 +25,22 @@
> #include <linux/amba/bus.h>
> #include <linux/amba/pl061.h>
>
> +#define GPIODIR 0x400
> +#define GPIOIS 0x404
> +#define GPIOIBE 0x408
> +#define GPIOIEV 0x40C
> +#define GPIOIE 0x410
> +#define GPIORIS 0x414
> +#define GPIOMIS 0x418
> +#define GPIOIC 0x41C
> +
> #define PL061_GPIO_NR 8
>
> +#define PL061_REG_SIZE (4*1024)
> +
> struct pl061_gpio {
> + struct list_head list;
Some commentary which describes this field would be nice. What lock
protects it, what other list_head this list is anchored to, etc
> /* Each of the two spinlocks protects a different set of hardware
> * regiters and data structurs. This decouples the code of the IRQ from
> * the GPIO code. This also makes the case of a GPIO routine call from
> @@ -37,12 +51,8 @@ struct pl061_gpio {
>
> void __iomem *base;
> struct gpio_chip gc;
> - struct work_struct gpio_free_work;
> - DECLARE_BITMAP(gpios_to_free, PL061_GPIO_NR);
> };
>
> -static u32 (*pl061_pending_irq)(int irq);
> -
> static int pl061_direction_input(struct gpio_chip *gc, unsigned offset)
> {
> struct pl061_gpio *chip = container_of(gc, struct pl061_gpio, gc);
> @@ -112,16 +122,6 @@ static void pl061_irq_disable(unsigned i
> spin_unlock_irqrestore(&chip->irq_lock, flags);
> }
>
> -static void pl061_irq_shutdown(unsigned irq)
> -{
> - struct pl061_gpio *chip = get_irq_chip_data(irq);
> - int offset = irq_to_gpio(irq) - chip->gc.base;
> -
> - pl061_irq_disable(irq);
> - set_bit(offset, chip->gpios_to_free);
> - schedule_work(&chip->gpio_free_work);
> -}
> -
> static void pl061_irq_enable(unsigned irq)
> {
> struct pl061_gpio *chip = get_irq_chip_data(irq);
> @@ -138,16 +138,10 @@ static void pl061_irq_enable(unsigned ir
>
> static unsigned int pl061_irq_startup(unsigned irq)
> {
> - int ret;
> -
> - ret = gpio_request(irq_to_gpio(irq), "IRQ");
> - if (ret < 0) {
> - pr_warning("%s: warning: gpio_request(%d) returned %d\n",
> - __func__, irq_to_gpio(irq), ret);
> - return 0;
> - }
> + if (gpio_request(irq_to_gpio(irq), "IRQ") == 0)
> + pr_warning("%s: warning: GPIO%d has not been requested\n",
> + __func__, irq_to_gpio(irq));
This is wrong, isn't it? gpio_request() returns 0 on success.
> - gpio_direction_input(irq_to_gpio(irq));
> pl061_irq_enable(irq);
>
> return 0;
> @@ -202,45 +196,38 @@ static struct irq_chip pl061_irqchip = {
> .startup = pl061_irq_startup,
> .enable = pl061_irq_enable,
> .disable = pl061_irq_disable,
> - .shutdown = pl061_irq_shutdown,
> .set_type = pl061_irq_type,
> };
>
> static void pl061_irq_handler(unsigned irq, struct irq_desc *desc)
> {
> + struct list_head *chip_list = get_irq_chip_data(irq);
> + struct list_head *ptr;
> + struct pl061_gpio *chip;
> +
> desc->chip->ack(irq);
> - while (1) {
> + list_for_each(ptr, chip_list) {
What locking protects the newly-added list?
> unsigned long pending;
> int gpio;
>
> - pending = pl061_pending_irq(irq);
> + chip = list_entry(ptr, struct pl061_gpio, list);
> + pending = readb(chip->base + GPIOMIS);
> + writeb(pending, chip->base + GPIOIC);
> +
> if (pending == 0)
> - break;
> + continue;
>
> - for_each_bit(gpio, &pending, BITS_PER_LONG)
> + for_each_bit(gpio, &pending, PL061_GPIO_NR)
> generic_handle_irq(gpio_to_irq(gpio));
> }
> desc->chip->unmask(irq);
> }
>
> -static void pl061_gpio_free(struct work_struct *work)
> -{
> - struct pl061_gpio *chip = container_of(work, struct pl061_gpio,
> - gpio_free_work);
> - int offset;
> -
> - for_each_bit(offset, chip->gpios_to_free, PL061_GPIO_NR) {
> - int gpio = offset + chip->gc.base;
> -
> - if (test_and_clear_bit(offset, chip->gpios_to_free))
> - gpio_free(gpio);
> - }
> -}
> -
> static int __init pl061_probe(struct amba_device *dev, struct amba_id *id)
> {
> struct pl061_platform_data *pdata;
> struct pl061_gpio *chip;
> + struct list_head *chip_list;
> int ret, irq, i;
>
> pdata = dev->dev.platform_data;
> @@ -251,12 +238,12 @@ static int __init pl061_probe(struct amb
> if (chip == NULL)
> return -ENOMEM;
>
> - if (request_mem_region(dev->res.start, SZ_4K, "pl061") == NULL) {
> + if (!request_mem_region(dev->res.start, PL061_REG_SIZE, "pl061")) {
> ret = -EBUSY;
> goto free_mem;
> }
>
> - chip->base = ioremap(dev->res.start, SZ_4K);
> + chip->base = ioremap(dev->res.start, PL061_REG_SIZE);
> if (chip->base == NULL) {
> ret = -ENOMEM;
> goto release_region;
> @@ -264,8 +251,7 @@ static int __init pl061_probe(struct amb
>
> spin_lock_init(&chip->lock);
> spin_lock_init(&chip->irq_lock);
> -
> - INIT_WORK(&chip->gpio_free_work, pl061_gpio_free);
> + INIT_LIST_HEAD(&chip->list);
>
> chip->gc.direction_input = pl061_direction_input;
> chip->gc.direction_output = pl061_direction_output;
> @@ -291,7 +277,17 @@ static int __init pl061_probe(struct amb
> goto iounmap;
> }
> set_irq_chained_handler(irq, pl061_irq_handler);
> - pl061_pending_irq = pdata->pending_irqs;
> + if (!pdata->is_irq_initialized || !pdata->is_irq_initialized(irq)) {
> + chip_list = kmalloc(sizeof(*chip_list), GFP_KERNEL);
> + if (chip_list == NULL) {
> + ret = -ENOMEM;
> + goto iounmap;
> + }
> + INIT_LIST_HEAD(chip_list);
> + set_irq_chip_data(irq, chip_list);
> + } else
> + chip_list = get_irq_chip_data(irq);
> + list_add(&chip->list, chip_list);
>
> for (i = 0; i < PL061_GPIO_NR; i++) {
> if (pdata->directions & (1 << i))
> @@ -312,7 +308,7 @@ static int __init pl061_probe(struct amb
> iounmap:
> iounmap(chip->base);
> release_region:
> - release_mem_region(dev->res.start, SZ_4K);
> + release_mem_region(dev->res.start, PL061_REG_SIZE);
> free_mem:
> kfree(chip);
>
> diff -puN include/linux/amba/pl061.h~gpio-driver-for-primecell-pl061-gpio-controller-v4 include/linux/amba/pl061.h
> --- a/include/linux/amba/pl061.h~gpio-driver-for-primecell-pl061-gpio-controller-v4
> +++ a/include/linux/amba/pl061.h
> @@ -1,18 +1,17 @@
> /* platform data for the PL061 GPIO driver */
>
> -#define GPIODIR 0x400
> -#define GPIOIS 0x404
> -#define GPIOIBE 0x408
> -#define GPIOIEV 0x40C
> -#define GPIOIE 0x410
> -#define GPIORIS 0x414
> -#define GPIOMIS 0x418
> -#define GPIOIC 0x41C
> -
> struct pl061_platform_data {
> /* number of the first GPIO */
> unsigned gpio_base;
> - u32 (*pending_irqs)(int irq);
> +
> u8 directions; /* startup directions, 1: out, 0: in */
> u8 values; /* startup values */
> +
> + /* This callback may be used when you have more than one PL061
> + * connected to the same IRQ trigger. This callback must return 0 on
> + * the first time it is called for each irq, and 1 on any other call.
> + * In case you are not unfortunate enough to have this setup, this
> + * pointer must be set to NULL.
> + */
> + int (*is_irq_initialized)(int irq);
> };
> _
>
>
--
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