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Date: Wed, 03 Apr 2013 13:04:26 +0200
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc: linux-kernel@...r.kernel.org,
Grant Likely <grant.likely@...retlab.ca>,
Linus Walleij <linus.walleij@...aro.org>,
"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
Mathias Nyman <mathias.nyman@...ux.intel.com>,
linux-acpi@...r.kernel.org
Subject: Re: [PATCH] gpiolib-acpi: introduce acpi_get_gpio_by_index() helper
On Wednesday, April 03, 2013 01:56:54 PM Mika Westerberg wrote:
> Instead of open-coding ACPI GPIO resource lookup in each driver, we provide
> a helper function analogous to Device Tree version that allows drivers to
> specify which GPIO resource they are interested (using an index to the GPIO
> resources). The function then finds out the correct resource, translates
> the ACPI GPIO number to the corresponding Linux GPIO number and returns
> that.
>
> Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
> Documentation/acpi/enumeration.txt | 32 ++++++++++++++-
> drivers/gpio/gpiolib-acpi.c | 77 ++++++++++++++++++++++++++++++++++++
> include/linux/acpi_gpio.h | 17 ++++++++
> 3 files changed, 125 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/acpi/enumeration.txt b/Documentation/acpi/enumeration.txt
> index 94a6561..b0d5410 100644
> --- a/Documentation/acpi/enumeration.txt
> +++ b/Documentation/acpi/enumeration.txt
> @@ -199,6 +199,8 @@ the device to the driver. For example:
> {
> Name (SBUF, ResourceTemplate()
> {
> + ...
> + // Used to power on/off the device
> GpioIo (Exclusive, PullDefault, 0x0000, 0x0000,
> IoRestrictionOutputOnly, "\\_SB.PCI0.GPI0",
> 0x00, ResourceConsumer,,)
> @@ -206,10 +208,20 @@ the device to the driver. For example:
> // Pin List
> 0x0055
> }
> +
> + // Interrupt for the device
> + GpioInt (Edge, ActiveHigh, ExclusiveAndWake, PullNone,
> + 0x0000, "\\_SB.PCI0.GPI0", 0x00, ResourceConsumer,,)
> + {
> + // Pin list
> + 0x0058
> + }
> +
> ...
>
> - Return (SBUF)
> }
> +
> + Return (SBUF)
> }
>
> These GPIO numbers are controller relative and path "\\_SB.PCI0.GPI0"
> @@ -220,6 +232,24 @@ The driver can do this by including <linux/acpi_gpio.h> and then calling
> acpi_get_gpio(path, gpio). This will return the Linux GPIO number or
> negative errno if there was no translation found.
>
> +In a simple case of just getting the Linux GPIO number from device
> +resources one can use acpi_get_gpio_by_index() helper function. It takes
> +pointer to the device and index of the GpioIo/GpioInt descriptor in the
> +device resources list. For example:
> +
> + int gpio_irq, gpio_power;
> + int ret;
> +
> + gpio_irq = acpi_get_gpio_by_index(dev, 1, NULL);
> + if (gpio_irq < 0)
> + /* handle error */
> +
> + gpio_power = acpi_get_gpio_by_index(dev, 0, NULL);
> + if (gpio_power < 0)
> + /* handle error */
> +
> + /* Now we can use the GPIO numbers */
> +
> Other GpioIo parameters must be converted first by the driver to be
> suitable to the gpiolib before passing them.
>
> diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
> index a063eb0..b66df3b 100644
> --- a/drivers/gpio/gpiolib-acpi.c
> +++ b/drivers/gpio/gpiolib-acpi.c
> @@ -54,6 +54,83 @@ int acpi_get_gpio(char *path, int pin)
> }
> EXPORT_SYMBOL_GPL(acpi_get_gpio);
>
> +struct acpi_gpio_lookup {
> + struct acpi_gpio_info info;
> + int index;
> + int gpio;
> + int n;
> +};
> +
> +static int acpi_find_gpio(struct acpi_resource *ares, void *data)
> +{
> + struct acpi_gpio_lookup *lookup = data;
> +
> + if (ares->type != ACPI_RESOURCE_TYPE_GPIO)
> + return 1;
> +
> + if (lookup->n++ == lookup->index && lookup->gpio < 0) {
> + const struct acpi_resource_gpio *agpio = &ares->data.gpio;
> +
> + lookup->gpio = acpi_get_gpio(agpio->resource_source.string_ptr,
> + agpio->pin_table[0]);
> + lookup->info.gpioint =
> + agpio->connection_type == ACPI_RESOURCE_GPIO_TYPE_INT;
> + }
> +
> + return 1;
> +}
> +
> +/**
> + * acpi_get_gpio_by_index() - get a GPIO number from device resources
> + * @dev: pointer to a device to get GPIO from
> + * @index: index of GpioIo/GpioInt resource (starting from %0)
> + * @info: info pointer to fill in (optional)
> + *
> + * Function goes through ACPI resources for @dev and based on @index looks
> + * up a GpioIo/GpioInt resource, translates it to the Linux GPIO number,
> + * and returns it. @index matches GpioIo/GpioInt resources only so if there
> + * are total %3 GPIO resources, the index goes from %0 to %2.
> + *
> + * If the GPIO cannot be translated or there is an error, negative errno is
> + * returned.
> + *
> + * Note: if the GPIO resource has multiple entries in the pin list, this
> + * function only returns the first.
> + */
> +int acpi_get_gpio_by_index(struct device *dev, int index,
> + struct acpi_gpio_info *info)
> +{
> + struct acpi_gpio_lookup lookup;
> + struct list_head resource_list;
> + struct acpi_device *adev;
> + acpi_handle handle;
> + int ret;
> +
> + if (!dev)
> + return -EINVAL;
> +
> + handle = ACPI_HANDLE(dev);
> + if (!handle || acpi_bus_get_device(handle, &adev))
> + return -ENODEV;
> +
> + memset(&lookup, 0, sizeof(lookup));
> + lookup.index = index;
> + lookup.gpio = -ENODEV;
> +
> + INIT_LIST_HEAD(&resource_list);
> + ret = acpi_dev_get_resources(adev, &resource_list, acpi_find_gpio,
> + &lookup);
> + if (ret < 0)
> + return ret;
> +
> + acpi_dev_free_resource_list(&resource_list);
> +
> + if (lookup.gpio >= 0 && info)
> + *info = lookup.info;
> +
> + return lookup.gpio;
> +}
> +EXPORT_SYMBOL_GPL(acpi_get_gpio_by_index);
>
> static irqreturn_t acpi_gpio_irq_handler(int irq, void *data)
> {
> diff --git a/include/linux/acpi_gpio.h b/include/linux/acpi_gpio.h
> index b76ebd0..598ea41 100644
> --- a/include/linux/acpi_gpio.h
> +++ b/include/linux/acpi_gpio.h
> @@ -1,12 +1,23 @@
> #ifndef _LINUX_ACPI_GPIO_H_
> #define _LINUX_ACPI_GPIO_H_
>
> +#include <linux/device.h>
> #include <linux/errno.h>
> #include <linux/gpio.h>
>
> +/**
> + * struct acpi_gpio_info - ACPI GPIO specific information
> + * @gpioint: if %true this GPIO is of type GpioInt otherwise type is GpioIo
> + */
> +struct acpi_gpio_info {
> + bool gpioint;
> +};
> +
> #ifdef CONFIG_GPIO_ACPI
>
> int acpi_get_gpio(char *path, int pin);
> +int acpi_get_gpio_by_index(struct device *dev, int index,
> + struct acpi_gpio_info *info);
> void acpi_gpiochip_request_interrupts(struct gpio_chip *chip);
>
> #else /* CONFIG_GPIO_ACPI */
> @@ -16,6 +27,12 @@ static inline int acpi_get_gpio(char *path, int pin)
> return -ENODEV;
> }
>
> +static inline int acpi_get_gpio_by_index(struct device *dev, int index,
> + struct acpi_gpio_info *info)
> +{
> + return -ENODEV;
> +}
> +
> static inline void acpi_gpiochip_request_interrupts(struct gpio_chip *chip) { }
>
> #endif /* CONFIG_GPIO_ACPI */
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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