Documentation: ACPI: move enumeration.txt to firmware-guide/acpi and convert to reST

This converts the plain text documentation to reStructuredText format
and adds it to Sphinx TOC tree.

No essential content change.

Signed-off-by: Changbin Du <changbin.du@gmail.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 0 insertions, 452 deletions

diff --git a/Documentation/acpi/enumeration.txt b/Documentation/acpi/enumeration.txt
deleted file mode 100644
index 1395b844649c..000000000000
--- a/Documentation/acpi/enumeration.txt
+++ /dev/null
@@ -1,452 +0,0 @@
-ACPI based device enumeration
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-ACPI 5 introduced a set of new resources (UartTSerialBus, I2cSerialBus,
-SpiSerialBus, GpioIo and GpioInt) which can be used in enumerating slave
-devices behind serial bus controllers.
-
-In addition we are starting to see peripherals integrated in the
-SoC/Chipset to appear only in ACPI namespace. These are typically devices
-that are accessed through memory-mapped registers.
-
-In order to support this and re-use the existing drivers as much as
-possible we decided to do following:
-
-	o Devices that have no bus connector resource are represented as
-	  platform devices.
-
-	o Devices behind real busses where there is a connector resource
-	  are represented as struct spi_device or struct i2c_device
-	  (standard UARTs are not busses so there is no struct uart_device).
-
-As both ACPI and Device Tree represent a tree of devices (and their
-resources) this implementation follows the Device Tree way as much as
-possible.
-
-The ACPI implementation enumerates devices behind busses (platform, SPI and
-I2C), creates the physical devices and binds them to their ACPI handle in
-the ACPI namespace.
-
-This means that when ACPI_HANDLE(dev) returns non-NULL the device was
-enumerated from ACPI namespace. This handle can be used to extract other
-device-specific configuration. There is an example of this below.
-
-Platform bus support
-~~~~~~~~~~~~~~~~~~~~
-Since we are using platform devices to represent devices that are not
-connected to any physical bus we only need to implement a platform driver
-for the device and add supported ACPI IDs. If this same IP-block is used on
-some other non-ACPI platform, the driver might work out of the box or needs
-some minor changes.
-
-Adding ACPI support for an existing driver should be pretty
-straightforward. Here is the simplest example:
-
-	#ifdef CONFIG_ACPI
-	static const struct acpi_device_id mydrv_acpi_match[] = {
-		/* ACPI IDs here */
-		{ }
-	};
-	MODULE_DEVICE_TABLE(acpi, mydrv_acpi_match);
-	#endif
-
-	static struct platform_driver my_driver = {
-		...
-		.driver = {
-			.acpi_match_table = ACPI_PTR(mydrv_acpi_match),
-		},
-	};
-
-If the driver needs to perform more complex initialization like getting and
-configuring GPIOs it can get its ACPI handle and extract this information
-from ACPI tables.
-
-DMA support
-~~~~~~~~~~~
-DMA controllers enumerated via ACPI should be registered in the system to
-provide generic access to their resources. For example, a driver that would
-like to be accessible to slave devices via generic API call
-dma_request_slave_channel() must register itself at the end of the probe
-function like this:
-
-	err = devm_acpi_dma_controller_register(dev, xlate_func, dw);
-	/* Handle the error if it's not a case of !CONFIG_ACPI */
-
-and implement custom xlate function if needed (usually acpi_dma_simple_xlate()
-is enough) which converts the FixedDMA resource provided by struct
-acpi_dma_spec into the corresponding DMA channel. A piece of code for that case
-could look like:
-
-	#ifdef CONFIG_ACPI
-	struct filter_args {
-		/* Provide necessary information for the filter_func */
-		...
-	};
-
-	static bool filter_func(struct dma_chan *chan, void *param)
-	{
-		/* Choose the proper channel */
-		...
-	}
-
-	static struct dma_chan *xlate_func(struct acpi_dma_spec *dma_spec,
-			struct acpi_dma *adma)
-	{
-		dma_cap_mask_t cap;
-		struct filter_args args;
-
-		/* Prepare arguments for filter_func */
-		...
-		return dma_request_channel(cap, filter_func, &args);
-	}
-	#else
-	static struct dma_chan *xlate_func(struct acpi_dma_spec *dma_spec,
-			struct acpi_dma *adma)
-	{
-		return NULL;
-	}
-	#endif
-
-dma_request_slave_channel() will call xlate_func() for each registered DMA
-controller. In the xlate function the proper channel must be chosen based on
-information in struct acpi_dma_spec and the properties of the controller
-provided by struct acpi_dma.
-
-Clients must call dma_request_slave_channel() with the string parameter that
-corresponds to a specific FixedDMA resource. By default "tx" means the first
-entry of the FixedDMA resource array, "rx" means the second entry. The table
-below shows a layout:
-
-	Device (I2C0)
-	{
-		...
-		Method (_CRS, 0, NotSerialized)
-		{
-			Name (DBUF, ResourceTemplate ()
-			{
-				FixedDMA (0x0018, 0x0004, Width32bit, _Y48)
-				FixedDMA (0x0019, 0x0005, Width32bit, )
-			})
-		...
-		}
-	}
-
-So, the FixedDMA with request line 0x0018 is "tx" and next one is "rx" in
-this example.
-
-In robust cases the client unfortunately needs to call
-acpi_dma_request_slave_chan_by_index() directly and therefore choose the
-specific FixedDMA resource by its index.
-
-SPI serial bus support
-~~~~~~~~~~~~~~~~~~~~~~
-Slave devices behind SPI bus have SpiSerialBus resource attached to them.
-This is extracted automatically by the SPI core and the slave devices are
-enumerated once spi_register_master() is called by the bus driver.
-
-Here is what the ACPI namespace for a SPI slave might look like:
-
-	Device (EEP0)
-	{
-		Name (_ADR, 1)
-		Name (_CID, Package() {
-			"ATML0025",
-			"AT25",
-		})
-		...
-		Method (_CRS, 0, NotSerialized)
-		{
-			SPISerialBus(1, PolarityLow, FourWireMode, 8,
-				ControllerInitiated, 1000000, ClockPolarityLow,
-				ClockPhaseFirst, "\\_SB.PCI0.SPI1",)
-		}
-		...
-
-The SPI device drivers only need to add ACPI IDs in a similar way than with
-the platform device drivers. Below is an example where we add ACPI support
-to at25 SPI eeprom driver (this is meant for the above ACPI snippet):
-
-	#ifdef CONFIG_ACPI
-	static const struct acpi_device_id at25_acpi_match[] = {
-		{ "AT25", 0 },
-		{ },
-	};
-	MODULE_DEVICE_TABLE(acpi, at25_acpi_match);
-	#endif
-
-	static struct spi_driver at25_driver = {
-		.driver = {
-			...
-			.acpi_match_table = ACPI_PTR(at25_acpi_match),
-		},
-	};
-
-Note that this driver actually needs more information like page size of the
-eeprom etc. but at the time writing this there is no standard way of
-passing those. One idea is to return this in _DSM method like:
-
-	Device (EEP0)
-	{
-		...
-		Method (_DSM, 4, NotSerialized)
-		{
-			Store (Package (6)
-			{
-				"byte-len", 1024,
-				"addr-mode", 2,
-				"page-size, 32
-			}, Local0)
-
-			// Check UUIDs etc.
-
-			Return (Local0)
-		}
-
-Then the at25 SPI driver can get this configuration by calling _DSM on its
-ACPI handle like:
-
-	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
-	struct acpi_object_list input;
-	acpi_status status;
-
-	/* Fill in the input buffer */
-
-	status = acpi_evaluate_object(ACPI_HANDLE(&spi->dev), "_DSM",
-				      &input, &output);
-	if (ACPI_FAILURE(status))
-		/* Handle the error */
-
-	/* Extract the data here */
-
-	kfree(output.pointer);
-
-I2C serial bus support
-~~~~~~~~~~~~~~~~~~~~~~
-The slaves behind I2C bus controller only need to add the ACPI IDs like
-with the platform and SPI drivers. The I2C core automatically enumerates
-any slave devices behind the controller device once the adapter is
-registered.
-
-Below is an example of how to add ACPI support to the existing mpu3050
-input driver:
-
-	#ifdef CONFIG_ACPI
-	static const struct acpi_device_id mpu3050_acpi_match[] = {
-		{ "MPU3050", 0 },
-		{ },
-	};
-	MODULE_DEVICE_TABLE(acpi, mpu3050_acpi_match);
-	#endif
-
-	static struct i2c_driver mpu3050_i2c_driver = {
-		.driver	= {
-			.name	= "mpu3050",
-			.owner	= THIS_MODULE,
-			.pm	= &mpu3050_pm,
-			.of_match_table = mpu3050_of_match,
-			.acpi_match_table = ACPI_PTR(mpu3050_acpi_match),
-		},
-		.probe		= mpu3050_probe,
-		.remove		= mpu3050_remove,
-		.id_table	= mpu3050_ids,
-	};
-
-GPIO support
-~~~~~~~~~~~~
-ACPI 5 introduced two new resources to describe GPIO connections: GpioIo
-and GpioInt. These resources can be used to pass GPIO numbers used by
-the device to the driver. ACPI 5.1 extended this with _DSD (Device
-Specific Data) which made it possible to name the GPIOs among other things.
-
-For example:
-
-Device (DEV)
-{
-	Method (_CRS, 0, NotSerialized)
-	{
-		Name (SBUF, ResourceTemplate()
-		{
-			...
-			// Used to power on/off the device
-			GpioIo (Exclusive, PullDefault, 0x0000, 0x0000,
-				IoRestrictionOutputOnly, "\\_SB.PCI0.GPI0",
-				0x00, ResourceConsumer,,)
-			{
-				// Pin List
-				0x0055
-			}
-
-			// Interrupt for the device
-			GpioInt (Edge, ActiveHigh, ExclusiveAndWake, PullNone,
-				 0x0000, "\\_SB.PCI0.GPI0", 0x00, ResourceConsumer,,)
-			{
-				// Pin list
-				0x0058
-			}
-
-			...
-
-		}
-
-		Return (SBUF)
-	}
-
-	// ACPI 5.1 _DSD used for naming the GPIOs
-	Name (_DSD, Package ()
-	{
-		ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
-		Package ()
-		{
-			Package () {"power-gpios", Package() {^DEV, 0, 0, 0 }},
-			Package () {"irq-gpios", Package() {^DEV, 1, 0, 0 }},
-		}
-	})
-	...
-
-These GPIO numbers are controller relative and path "\\_SB.PCI0.GPI0"
-specifies the path to the controller. In order to use these GPIOs in Linux
-we need to translate them to the corresponding Linux GPIO descriptors.
-
-There is a standard GPIO API for that and is documented in
-Documentation/gpio/.
-
-In the above example we can get the corresponding two GPIO descriptors with
-a code like this:
-
-	#include <linux/gpio/consumer.h>
-	...
-
-	struct gpio_desc *irq_desc, *power_desc;
-
-	irq_desc = gpiod_get(dev, "irq");
-	if (IS_ERR(irq_desc))
-		/* handle error */
-
-	power_desc = gpiod_get(dev, "power");
-	if (IS_ERR(power_desc))
-		/* handle error */
-
-	/* Now we can use the GPIO descriptors */
-
-There are also devm_* versions of these functions which release the
-descriptors once the device is released.
-
-See Documentation/acpi/gpio-properties.txt for more information about the
-_DSD binding related to GPIOs.
-
-MFD devices
-~~~~~~~~~~~
-The MFD devices register their children as platform devices. For the child
-devices there needs to be an ACPI handle that they can use to reference
-parts of the ACPI namespace that relate to them. In the Linux MFD subsystem
-we provide two ways:
-
-	o The children share the parent ACPI handle.
-	o The MFD cell can specify the ACPI id of the device.
-
-For the first case, the MFD drivers do not need to do anything. The
-resulting child platform device will have its ACPI_COMPANION() set to point
-to the parent device.
-
-If the ACPI namespace has a device that we can match using an ACPI id or ACPI
-adr, the cell should be set like:
-
-	static struct mfd_cell_acpi_match my_subdevice_cell_acpi_match = {
-		.pnpid = "XYZ0001",
-		.adr = 0,
-	};
-
-	static struct mfd_cell my_subdevice_cell = {
-		.name = "my_subdevice",
-		/* set the resources relative to the parent */
-		.acpi_match = &my_subdevice_cell_acpi_match,
-	};
-
-The ACPI id "XYZ0001" is then used to lookup an ACPI device directly under
-the MFD device and if found, that ACPI companion device is bound to the
-resulting child platform device.
-
-Device Tree namespace link device ID
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The Device Tree protocol uses device identification based on the "compatible"
-property whose value is a string or an array of strings recognized as device
-identifiers by drivers and the driver core.  The set of all those strings may be
-regarded as a device identification namespace analogous to the ACPI/PNP device
-ID namespace.  Consequently, in principle it should not be necessary to allocate
-a new (and arguably redundant) ACPI/PNP device ID for a devices with an existing
-identification string in the Device Tree (DT) namespace, especially if that ID
-is only needed to indicate that a given device is compatible with another one,
-presumably having a matching driver in the kernel already.
-
-In ACPI, the device identification object called _CID (Compatible ID) is used to
-list the IDs of devices the given one is compatible with, but those IDs must
-belong to one of the namespaces prescribed by the ACPI specification (see
-Section 6.1.2 of ACPI 6.0 for details) and the DT namespace is not one of them.
-Moreover, the specification mandates that either a _HID or an _ADR identification
-object be present for all ACPI objects representing devices (Section 6.1 of ACPI
-6.0).  For non-enumerable bus types that object must be _HID and its value must
-be a device ID from one of the namespaces prescribed by the specification too.
-
-The special DT namespace link device ID, PRP0001, provides a means to use the
-existing DT-compatible device identification in ACPI and to satisfy the above
-requirements following from the ACPI specification at the same time.  Namely,
-if PRP0001 is returned by _HID, the ACPI subsystem will look for the
-"compatible" property in the device object's _DSD and will use the value of that
-property to identify the corresponding device in analogy with the original DT
-device identification algorithm.  If the "compatible" property is not present
-or its value is not valid, the device will not be enumerated by the ACPI
-subsystem.  Otherwise, it will be enumerated automatically as a platform device
-(except when an I2C or SPI link from the device to its parent is present, in
-which case the ACPI core will leave the device enumeration to the parent's
-driver) and the identification strings from the "compatible" property value will
-be used to find a driver for the device along with the device IDs listed by _CID
-(if present).
-
-Analogously, if PRP0001 is present in the list of device IDs returned by _CID,
-the identification strings listed by the "compatible" property value (if present
-and valid) will be used to look for a driver matching the device, but in that
-case their relative priority with respect to the other device IDs listed by
-_HID and _CID depends on the position of PRP0001 in the _CID return package.
-Specifically, the device IDs returned by _HID and preceding PRP0001 in the _CID
-return package will be checked first.  Also in that case the bus type the device
-will be enumerated to depends on the device ID returned by _HID.
-
-For example, the following ACPI sample might be used to enumerate an lm75-type
-I2C temperature sensor and match it to the driver using the Device Tree
-namespace link:
-
-	Device (TMP0)
-	{
-		Name (_HID, "PRP0001")
-		Name (_DSD, Package() {
-			ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
-			Package () {
-				Package (2) { "compatible", "ti,tmp75" },
-			}
-		})
-		Method (_CRS, 0, Serialized)
-		{
-			Name (SBUF, ResourceTemplate ()
-			{
-				I2cSerialBusV2 (0x48, ControllerInitiated,
-					400000, AddressingMode7Bit,
-					"\\_SB.PCI0.I2C1", 0x00,
-					ResourceConsumer, , Exclusive,)
-			})
-			Return (SBUF)
-		}
-	}
-
-It is valid to define device objects with a _HID returning PRP0001 and without
-the "compatible" property in the _DSD or a _CID as long as one of their
-ancestors provides a _DSD with a valid "compatible" property.  Such device
-objects are then simply regarded as additional "blocks" providing hierarchical
-configuration information to the driver of the composite ancestor device.
-
-However, PRP0001 can only be returned from either _HID or _CID of a device
-object if all of the properties returned by the _DSD associated with it (either
-the _DSD of the device object itself or the _DSD of its ancestor in the
-"composite device" case described above) can be used in the ACPI environment.
-Otherwise, the _DSD itself is regarded as invalid and therefore the "compatible"
-property returned by it is meaningless.
-
-Refer to DSD-properties-rules.txt for more information.