On Thu, Oct 22, 2015 at 10:32:25AM +0200, Linus Walleij wrote:
> GPIO chips have been around for years, but were never real devices,
> instead they were piggy-backing on a parent device (such as a
> platform_device or amba_device) but this was always optional.
> GPIO chips could also exist without any device at all, with its
> struct device *dev pointer being set to null.
>
> When sysfs was in use, a mock device would be created, with the
> optional parent assigned, or just floating orphaned with NULL
> as parent.
>
> For a proper userspace ABI we need gpiochips to *always have a
> populated struct device, so add this in the gpio_chip struct.
> The name "dev" is unfortunately already take so we use "device"
> to name it.
>
> If sysfs is active, it will use this device as parent, and the
> former parent device "dev" will be set as parent of the new
> "device" struct member.
>
> From this point on, gpiochips are devices.
>
> Cc: Johan Hovold <jo...@kernel.org>
> Cc: Michael Welling <mwell...@ieee.org>
> Cc: Markus Pargmann <m...@pengutronix.de>
> Signed-off-by: Linus Walleij <linus.wall...@linaro.org>
> ---
> drivers/gpio/gpiolib-sysfs.c | 2 +-
> drivers/gpio/gpiolib.c | 44
> +++++++++++++++++++++++++++++++++++++++-----
> include/linux/gpio/driver.h | 9 +++++++--
> 3 files changed, 47 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
> index b57ed8e55ab5..7e5bc5736e47 100644
> --- a/drivers/gpio/gpiolib-sysfs.c
> +++ b/drivers/gpio/gpiolib-sysfs.c
> @@ -605,7 +605,7 @@ int gpiod_export(struct gpio_desc *desc, bool
> direction_may_change)
> if (chip->names && chip->names[offset])
> ioname = chip->names[offset];
>
> - dev = device_create_with_groups(&gpio_class, chip->dev,
> + dev = device_create_with_groups(&gpio_class, &chip->device,
> MKDEV(0, 0), data, gpio_groups,
> ioname ? ioname : "gpio%u",
> desc_to_gpio(desc));
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 6798355c61c6..0ab4f75b7f8e 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -16,6 +16,7 @@
> #include <linux/gpio/driver.h>
> #include <linux/gpio/machine.h>
> #include <linux/pinctrl/consumer.h>
> +#include <linux/idr.h>
>
> #include "gpiolib.h"
>
> @@ -42,6 +43,9 @@
> #define extra_checks 0
> #endif
>
> +/* Device and char device-related information */
> +static DEFINE_IDA(gpio_ida);
> +
> /* gpio_lock prevents conflicts during gpio_desc[] table updates.
> * While any GPIO is requested, its gpio_chip is not removable;
> * each GPIO's "requested" flag serves as a lock and refcount.
> @@ -52,7 +56,6 @@ static DEFINE_MUTEX(gpio_lookup_lock);
> static LIST_HEAD(gpio_lookup_list);
> LIST_HEAD(gpio_chips);
>
> -
> static void gpiochip_free_hogs(struct gpio_chip *chip);
> static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip);
>
> @@ -300,7 +303,7 @@ int gpiochip_add(struct gpio_chip *chip)
> {
> unsigned long flags;
> int status = 0;
> - unsigned id;
> + unsigned i;
> int base = chip->base;
> struct gpio_desc *descs;
>
> @@ -308,6 +311,28 @@ int gpiochip_add(struct gpio_chip *chip)
> if (!descs)
> return -ENOMEM;
>
> + /*
> + * The "dev" member of gpiochip is the parent, and the actual
> + * device is named "device" for historical reasons.
> + *
> + * We memset the struct to zero to avoid reentrance issues.
> + */
> + memset(&chip->device, 0, sizeof(chip->device));
> + if (chip->dev) {
> + chip->device.parent = chip->dev;
> + chip->device.of_node = chip->dev->of_node;
> + } else {
> +#ifdef CONFIG_OF_GPIO
> + /* If the gpiochip has an assigned OF node this takes precedence */
> + if (chip->of_node)
> + chip->device.of_node = chip->of_node;
This is in the else case. I think this should be indented an additional
level.
Best Regards,
Markus
> +#endif
> + }
> + chip->id = ida_simple_get(&gpio_ida, 0, 0, GFP_KERNEL);
> + dev_set_name(&chip->device, "gpiochip%d", chip->id);
> + device_initialize(&chip->device);
> + dev_set_drvdata(&chip->device, chip);
> +
> spin_lock_irqsave(&gpio_lock, flags);
>
> if (base < 0) {
> @@ -326,8 +351,8 @@ int gpiochip_add(struct gpio_chip *chip)
> goto err_free_descs;
> }
>
> - for (id = 0; id < chip->ngpio; id++) {
> - struct gpio_desc *desc = &descs[id];
> + for (i = 0; i < chip->ngpio; i++) {
> + struct gpio_desc *desc = &descs[i];
>
> desc->chip = chip;
>
> @@ -361,16 +386,22 @@ int gpiochip_add(struct gpio_chip *chip)
>
> acpi_gpiochip_add(chip);
>
> - status = gpiochip_sysfs_register(chip);
> + status = device_add(&chip->device);
> if (status)
> goto err_remove_chip;
>
> + status = gpiochip_sysfs_register(chip);
> + if (status)
> + goto err_remove_device;
> +
> pr_debug("%s: registered GPIOs %d to %d on device: %s\n", __func__,
> chip->base, chip->base + chip->ngpio - 1,
> chip->label ? : "generic");
>
> return 0;
>
> +err_remove_device:
> + device_del(&chip->device);
> err_remove_chip:
> acpi_gpiochip_remove(chip);
> gpiochip_free_hogs(chip);
> @@ -381,6 +412,7 @@ err_remove_from_list:
> spin_unlock_irqrestore(&gpio_lock, flags);
> chip->desc = NULL;
> err_free_descs:
> + ida_simple_remove(&gpio_ida, chip->id);
> kfree(descs);
>
> /* failures here can mean systems won't boot... */
> @@ -426,6 +458,8 @@ void gpiochip_remove(struct gpio_chip *chip)
> if (requested)
> dev_crit(chip->dev, "REMOVING GPIOCHIP WITH GPIOS STILL
> REQUESTED\n");
>
> + device_del(&chip->device);
> + ida_simple_remove(&gpio_ida, chip->id);
> kfree(chip->desc);
> chip->desc = NULL;
> }
> diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
> index d1baebf350d8..cf3028eccc4b 100644
> --- a/include/linux/gpio/driver.h
> +++ b/include/linux/gpio/driver.h
> @@ -1,6 +1,7 @@
> #ifndef __LINUX_GPIO_DRIVER_H
> #define __LINUX_GPIO_DRIVER_H
>
> +#include <linux/device.h>
> #include <linux/types.h>
> #include <linux/module.h>
> #include <linux/irq.h>
> @@ -8,8 +9,8 @@
> #include <linux/irqdomain.h>
> #include <linux/lockdep.h>
> #include <linux/pinctrl/pinctrl.h>
> +#include <linux/cdev.h>
>
> -struct device;
> struct gpio_desc;
> struct of_phandle_args;
> struct device_node;
> @@ -20,7 +21,9 @@ struct seq_file;
> /**
> * struct gpio_chip - abstract a GPIO controller
> * @label: for diagnostics
> - * @dev: optional device providing the GPIOs
> + * @id: numerical ID number for the GPIO chip
> + * @device: the GPIO device struct.
> + * @dev: optional parent device (hardware) providing the GPIOs
> * @cdev: class device used by sysfs interface (may be NULL)
> * @owner: helps prevent removal of modules exporting active GPIOs
> * @list: links gpio_chips together for traversal
> @@ -89,6 +92,8 @@ struct seq_file;
> */
> struct gpio_chip {
> const char *label;
> + int id;
> + struct device device;
> struct device *dev;
> struct device *cdev;
> struct module *owner;
> --
> 2.4.3
>
>
--
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