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Date: Tue, 14 Oct 2014 15:44:03 +0200
From: Grant Likely <grant.likely@...aro.org>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Mika Westerberg <mika.westerberg@...ux.intel.com>,
ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
Aaron Lu <aaron.lu@...el.com>, devicetree@...r.kernel.org,
Linus Walleij <linus.walleij@...aro.org>,
Alexandre Courbot <gnurou@...il.com>,
Dmitry Torokhov <dmitry.torokhov@...il.com>,
Bryan Wu <cooloney@...il.com>, Arnd Bergmann <arnd@...db.de>,
Darren Hart <dvhart@...ux.intel.com>,
Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH 06/13] gpio / ACPI: Add support for _DSD device
properties
On Tue, 07 Oct 2014 02:15:18 +0200
, "Rafael J. Wysocki" <rjw@...ysocki.net>
wrote:
> From: Mika Westerberg <mika.westerberg@...ux.intel.com>
>
> With release of ACPI 5.1 and _DSD method we can finally name GPIOs (and
> other things as well) returned by _CRS. Previously we were only able to
> use integer index to find the corresponding GPIO, which is pretty error
> prone if the order changes.
>
> With _DSD we can now query GPIOs using name instead of an integer index,
> like the below example shows:
>
> // Bluetooth device with reset and shutdown GPIOs
> Device (BTH)
> {
> Name (_HID, ...)
>
> Name (_CRS, ResourceTemplate ()
> {
> GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly,
> "\\_SB.GPO0", 0, ResourceConsumer) {15}
> GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly,
> "\\_SB.GPO0", 0, ResourceConsumer) {27, 31}
> })
>
> Name (_DSD, Package ()
> {
> ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
> Package ()
> {
> Package () {"reset-gpio", Package() {^BTH, 1, 1, 0 }},
> Package () {"shutdown-gpio", Package() {^BTH, 0, 0, 0 }},
> }
> })
> }
>
> The format of the supported GPIO property is:
>
> Package () { "name", Package () { ref, index, pin, active_low }}
>
> ref - The device that has _CRS containing GpioIo()/GpioInt() resources,
> typically this is the device itself (BTH in our case).
> index - Index of the GpioIo()/GpioInt() resource in _CRS starting from zero.
> pin - Pin in the GpioIo()/GpioInt() resource. Typically this is zero.
> active_low - If 1 the GPIO is marked as active_low.
>
> Since ACPI GpioIo() resource does not have field saying whether it is
> active low or high, the "active_low" argument can be used here. Setting
> it to 1 marks the GPIO as active low.
>
> In our Bluetooth example the "reset-gpio" refers to the second GpioIo()
> resource, second pin in that resource with the GPIO number of 31.
>
> This patch implements necessary support to gpiolib for extracting GPIOs
> using _DSD device properties.
Patch looks good, but please put the above description into
/Documentation until we've got a better place to document extra bindings.
g.
>
> Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> Acked-by: Linus Walleij <linus.walleij@...aro.org>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
> drivers/gpio/gpiolib-acpi.c | 78 +++++++++++++++++++++++++++++++++++++--------
> drivers/gpio/gpiolib.c | 30 ++++++++++++++---
> drivers/gpio/gpiolib.h | 7 ++--
> 3 files changed, 94 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
> index 687476f..b14c045 100644
> --- a/drivers/gpio/gpiolib-acpi.c
> +++ b/drivers/gpio/gpiolib-acpi.c
> @@ -293,6 +293,7 @@ void acpi_gpiochip_free_interrupts(struct gpio_chip *chip)
> struct acpi_gpio_lookup {
> struct acpi_gpio_info info;
> int index;
> + int pin_index;
> struct gpio_desc *desc;
> int n;
> };
> @@ -306,13 +307,24 @@ static int acpi_find_gpio(struct acpi_resource *ares, void *data)
>
> if (lookup->n++ == lookup->index && !lookup->desc) {
> const struct acpi_resource_gpio *agpio = &ares->data.gpio;
> + int pin_index = lookup->pin_index;
> +
> + if (pin_index >= agpio->pin_table_length)
> + return 1;
>
> lookup->desc = acpi_get_gpiod(agpio->resource_source.string_ptr,
> - agpio->pin_table[0]);
> + agpio->pin_table[pin_index]);
> lookup->info.gpioint =
> agpio->connection_type == ACPI_RESOURCE_GPIO_TYPE_INT;
> - lookup->info.active_low =
> - agpio->polarity == ACPI_ACTIVE_LOW;
> +
> + /*
> + * ActiveLow is only specified for GpioInt resource. If
> + * GpioIo is used then the only way to set the flag is
> + * to use _DSD "gpios" property.
> + */
> + if (lookup->info.gpioint)
> + lookup->info.active_low =
> + agpio->polarity == ACPI_ACTIVE_LOW;
> }
>
> return 1;
> @@ -320,40 +332,75 @@ static int acpi_find_gpio(struct acpi_resource *ares, void *data)
>
> /**
> * acpi_get_gpiod_by_index() - get a GPIO descriptor from device resources
> - * @dev: pointer to a device to get GPIO from
> + * @adev: pointer to a ACPI device to get GPIO from
> + * @propname: Property name of the GPIO (optional)
> * @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
> + * Function goes through ACPI resources for @adev and based on @index looks
> * up a GpioIo/GpioInt resource, translates it to the Linux GPIO descriptor,
> * 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 @propname is specified the GPIO is looked using device property. In
> + * that case @index is used to select the GPIO entry in the property value
> + * (in case of multiple).
> + *
> * If the GPIO cannot be translated or there is an error an ERR_PTR is
> * returned.
> *
> * Note: if the GPIO resource has multiple entries in the pin list, this
> * function only returns the first.
> */
> -struct gpio_desc *acpi_get_gpiod_by_index(struct device *dev, int index,
> +struct gpio_desc *acpi_get_gpiod_by_index(struct acpi_device *adev,
> + const char *propname, int index,
> struct acpi_gpio_info *info)
> {
> struct acpi_gpio_lookup lookup;
> struct list_head resource_list;
> - struct acpi_device *adev;
> - acpi_handle handle;
> + bool active_low = false;
> int ret;
>
> - if (!dev)
> - return ERR_PTR(-EINVAL);
> -
> - handle = ACPI_HANDLE(dev);
> - if (!handle || acpi_bus_get_device(handle, &adev))
> + if (!adev)
> return ERR_PTR(-ENODEV);
>
> memset(&lookup, 0, sizeof(lookup));
> lookup.index = index;
>
> + if (propname) {
> + struct acpi_reference_args args;
> +
> + dev_dbg(&adev->dev, "GPIO: looking up %s\n", propname);
> +
> + memset(&args, 0, sizeof(args));
> + ret = acpi_dev_get_property_reference(adev, propname, NULL,
> + index, &args);
> + if (ret)
> + return ERR_PTR(ret);
> +
> + /*
> + * The property was found and resolved so need to
> + * lookup the GPIO based on returned args instead.
> + */
> + adev = args.adev;
> + if (args.nargs >= 2) {
> + lookup.index = args.args[0];
> + lookup.pin_index = args.args[1];
> + /*
> + * 3rd argument, if present is used to
> + * specify active_low.
> + */
> + if (args.nargs >= 3)
> + active_low = !!args.args[2];
> + }
> +
> + dev_dbg(&adev->dev, "GPIO: _DSD returned %s %zd %llu %llu %llu\n",
> + dev_name(&adev->dev), args.nargs,
> + args.args[0], args.args[1], args.args[2]);
> + } else {
> + dev_dbg(&adev->dev, "GPIO: looking up %d in _CRS\n", index);
> + }
> +
> INIT_LIST_HEAD(&resource_list);
> ret = acpi_dev_get_resources(adev, &resource_list, acpi_find_gpio,
> &lookup);
> @@ -362,8 +409,11 @@ struct gpio_desc *acpi_get_gpiod_by_index(struct device *dev, int index,
>
> acpi_dev_free_resource_list(&resource_list);
>
> - if (lookup.desc && info)
> + if (lookup.desc && info) {
> *info = lookup.info;
> + if (active_low)
> + info->active_low = active_low;
> + }
>
> return lookup.desc ? lookup.desc : ERR_PTR(-ENOENT);
> }
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index c68d037..4c86601 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1487,14 +1487,36 @@ static struct gpio_desc *acpi_find_gpio(struct device *dev, const char *con_id,
> unsigned int idx,
> enum gpio_lookup_flags *flags)
> {
> + static const char * const suffixes[] = { "gpios", "gpio" };
> + struct acpi_device *adev = ACPI_COMPANION(dev);
> struct acpi_gpio_info info;
> struct gpio_desc *desc;
> + char propname[32];
> + int i;
>
> - desc = acpi_get_gpiod_by_index(dev, idx, &info);
> - if (IS_ERR(desc))
> - return desc;
> + /* Try first from _DSD */
> + for (i = 0; i < ARRAY_SIZE(suffixes); i++) {
> + if (con_id && strcmp(con_id, "gpios")) {
> + snprintf(propname, sizeof(propname), "%s-%s",
> + con_id, suffixes[i]);
> + } else {
> + snprintf(propname, sizeof(propname), "%s",
> + suffixes[i]);
> + }
> +
> + desc = acpi_get_gpiod_by_index(adev, propname, 0, &info);
> + if (!IS_ERR(desc) || (PTR_ERR(desc) == -EPROBE_DEFER))
> + break;
> + }
> +
> + /* Then from plain _CRS GPIOs */
> + if (IS_ERR(desc)) {
> + desc = acpi_get_gpiod_by_index(adev, NULL, idx, &info);
> + if (IS_ERR(desc))
> + return desc;
> + }
>
> - if (info.gpioint && info.active_low)
> + if (info.active_low)
> *flags |= GPIO_ACTIVE_LOW;
>
> return desc;
> diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
> index 9db2b6a..e3a5211 100644
> --- a/drivers/gpio/gpiolib.h
> +++ b/drivers/gpio/gpiolib.h
> @@ -34,7 +34,8 @@ void acpi_gpiochip_remove(struct gpio_chip *chip);
> void acpi_gpiochip_request_interrupts(struct gpio_chip *chip);
> void acpi_gpiochip_free_interrupts(struct gpio_chip *chip);
>
> -struct gpio_desc *acpi_get_gpiod_by_index(struct device *dev, int index,
> +struct gpio_desc *acpi_get_gpiod_by_index(struct acpi_device *adev,
> + const char *propname, int index,
> struct acpi_gpio_info *info);
> #else
> static inline void acpi_gpiochip_add(struct gpio_chip *chip) { }
> @@ -47,8 +48,8 @@ static inline void
> acpi_gpiochip_free_interrupts(struct gpio_chip *chip) { }
>
> static inline struct gpio_desc *
> -acpi_get_gpiod_by_index(struct device *dev, int index,
> - struct acpi_gpio_info *info)
> +acpi_get_gpiod_by_index(struct acpi_device *adev, const char *propname,
> + int index, struct acpi_gpio_info *info)
> {
> return ERR_PTR(-ENOSYS);
> }
> --
> 1.9.3
>
>
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