Merge branch 'device-properties' (d3eaf587) · Commits · e / devices / android_kernel_oneplus_sm7250

Documentation/acpi/gpio-properties.txt

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		_DSD Device Properties Related to GPIO
		--------------------------------------

		With the release of ACPI 5.1 and the _DSD configuration objecte names
		can finally be given to GPIOs (and other things as well) returned by
		_CRS. Previously, we were only able to use an integer index to find
		the corresponding GPIO, which is pretty error prone (it depends on
		the _CRS output ordering, for example).

		With _DSD we can now query GPIOs using a name instead of an integer
		index, like the ASL example below 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 a 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.

		ACPI GPIO Mappings Provided by Drivers
		--------------------------------------

		There are systems in which the ACPI tables do not contain _DSD but provide _CRS
		with GpioIo()/GpioInt() resources and device drivers still need to work with
		them.

		In those cases ACPI device identification objects, _HID, _CID, _CLS, _SUB, _HRV,
		available to the driver can be used to identify the device and that is supposed
		to be sufficient to determine the meaning and purpose of all of the GPIO lines
		listed by the GpioIo()/GpioInt() resources returned by _CRS. In other words,
		the driver is supposed to know what to use the GpioIo()/GpioInt() resources for
		once it has identified the device. Having done that, it can simply assign names
		to the GPIO lines it is going to use and provide the GPIO subsystem with a
		mapping between those names and the ACPI GPIO resources corresponding to them.

		To do that, the driver needs to define a mapping table as a NULL-terminated
		array of struct acpi_gpio_mapping objects that each contain a name, a pointer
		to an array of line data (struct acpi_gpio_params) objects and the size of that
		array. Each struct acpi_gpio_params object consists of three fields,
		crs_entry_index, line_index, active_low, representing the index of the target
		GpioIo()/GpioInt() resource in _CRS starting from zero, the index of the target
		line in that resource starting from zero, and the active-low flag for that line,
		respectively, in analogy with the _DSD GPIO property format specified above.

		For the example Bluetooth device discussed previously the data structures in
		question would look like this:

		static const struct acpi_gpio_params reset_gpio = { 1, 1, false };
		static const struct acpi_gpio_params shutdown_gpio = { 0, 0, false };

		static const struct acpi_gpio_mapping bluetooth_acpi_gpios[] = {
		{ "reset-gpio", &reset_gpio, 1 },
		{ "shutdown-gpio", &shutdown_gpio, 1 },
		{ },
		};

		Next, the mapping table needs to be passed as the second argument to
		acpi_dev_add_driver_gpios() that will register it with the ACPI device object
		pointed to by its first argument. That should be done in the driver's .probe()
		routine. On removal, the driver should unregister its GPIO mapping table by
		calling acpi_dev_remove_driver_gpios() on the ACPI device object where that
		table was previously registered.

Documentation/gpio/consumer.txt

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		@@ -219,6 +219,24 @@ part of the IRQ interface, e.g. IRQF_TRIGGER_FALLING, as are system wakeup
		capabilities.


		GPIOs and ACPI
		==============

		On ACPI systems, GPIOs are described by GpioIo()/GpioInt() resources listed by
		the _CRS configuration objects of devices. Those resources do not provide
		connection IDs (names) for GPIOs, so it is necessary to use an additional
		mechanism for this purpose.

		Systems compliant with ACPI 5.1 or newer may provide a _DSD configuration object
		which, among other things, may be used to provide connection IDs for specific
		GPIOs described by the GpioIo()/GpioInt() resources in _CRS. If that is the
		case, it will be handled by the GPIO subsystem automatically. However, if the
		_DSD is not present, the mappings between GpioIo()/GpioInt() resources and GPIO
		connection IDs need to be provided by device drivers.

		For details refer to Documentation/acpi/gpio-properties.txt


		Interacting With the Legacy GPIO Subsystem
		==========================================
		Many kernel subsystems still handle GPIOs using the legacy integer-based

arch/arm/mach-s3c24xx/h1940-bluetooth.c

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		@@ -41,7 +41,7 @@ static void h1940bt_enable(int on)
		mdelay(10);
		gpio_set_value(S3C2410_GPH(1), 0);

		h1940_led_blink_set(-EINVAL, GPIO_LED_BLINK, NULL, NULL);
		h1940_led_blink_set(NULL, GPIO_LED_BLINK, NULL, NULL);
		}
		else {
		gpio_set_value(S3C2410_GPH(1), 1);
		@@ -50,7 +50,7 @@ static void h1940bt_enable(int on)
		mdelay(10);
		gpio_set_value(H1940_LATCH_BLUETOOTH_POWER, 0);

		h1940_led_blink_set(-EINVAL, GPIO_LED_NO_BLINK_LOW, NULL, NULL);
		h1940_led_blink_set(NULL, GPIO_LED_NO_BLINK_LOW, NULL, NULL);
		}
		}

arch/arm/mach-s3c24xx/h1940.h

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		@@ -19,8 +19,10 @@
		#define H1940_SUSPEND_RESUMEAT (0x30081000)
		#define H1940_SUSPEND_CHECK (0x30080000)

		struct gpio_desc;

		extern void h1940_pm_return(void);
		extern int h1940_led_blink_set(unsigned gpio, int state,
		extern int h1940_led_blink_set(struct gpio_desc *desc, int state,
		unsigned long *delay_on,
		unsigned long *delay_off);

arch/arm/mach-s3c24xx/mach-h1940.c

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		@@ -359,10 +359,11 @@ static struct platform_device h1940_battery = {

		static DEFINE_SPINLOCK(h1940_blink_spin);

		int h1940_led_blink_set(unsigned gpio, int state,
		int h1940_led_blink_set(struct gpio_desc *desc, int state,
		unsigned long delay_on, unsigned long delay_off)
		{
		int blink_gpio, check_gpio1, check_gpio2;
		int gpio = desc ? desc_to_gpio(desc) : -EINVAL;

		switch (gpio) {
		case H1940_LATCH_LED_GREEN: