Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 690 insertions, 0 deletions

diff --git a/Documentation/firmware-guide/acpi/enumeration.rst b/Documentation/firmware-guide/acpi/enumeration.rst
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+.. SPDX-License-Identifier: GPL-2.0
+
+=============================
+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:
+
+  - Devices that have no bus connector resource are represented as
+    platform devices.
+
+  - Devices behind real busses where there is a connector resource
+    are represented as struct spi_device or struct i2c_client. Note
+    that standard UARTs are not busses so there is no struct uart_device,
+    although some of them may be represented by struct serdev_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,
+I2C, and in some cases UART), 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::
+
+	static const struct acpi_device_id mydrv_acpi_match[] = {
+		/* ACPI IDs here */
+		{ }
+	};
+	MODULE_DEVICE_TABLE(acpi, mydrv_acpi_match);
+
+	static struct platform_driver my_driver = {
+		...
+		.driver = {
+			.acpi_match_table = 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_chan() 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_chan() 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_chan() 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.
+
+Named Interrupts
+================
+
+Drivers enumerated via ACPI can have names to interrupts in the ACPI table
+which can be used to get the IRQ number in the driver.
+
+The interrupt name can be listed in _DSD as 'interrupt-names'. The names
+should be listed as an array of strings which will map to the Interrupt()
+resource in the ACPI table corresponding to its index.
+
+The table below shows an example of its usage::
+
+    Device (DEV0) {
+        ...
+        Name (_CRS, ResourceTemplate() {
+            ...
+            Interrupt (ResourceConsumer, Level, ActiveHigh, Exclusive) {
+                0x20,
+                0x24
+            }
+        })
+
+        Name (_DSD, Package () {
+            ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+            Package () {
+                Package () { "interrupt-names", Package () { "default", "alert" } },
+            }
+        ...
+        })
+    }
+
+The interrupt name 'default' will correspond to 0x20 in Interrupt()
+resource and 'alert' to 0x24. Note that only the Interrupt() resource
+is mapped and not GpioInt() or similar.
+
+The driver can call the function - fwnode_irq_get_byname() with the fwnode
+and interrupt name as arguments to get the corresponding IRQ number.
+
+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 to
+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)::
+
+	static const struct acpi_device_id at25_acpi_match[] = {
+		{ "AT25", 0 },
+		{ }
+	};
+	MODULE_DEVICE_TABLE(acpi, at25_acpi_match);
+
+	static struct spi_driver at25_driver = {
+		.driver = {
+			...
+			.acpi_match_table = at25_acpi_match,
+		},
+	};
+
+Note that this driver actually needs more information like page size of the
+eeprom, etc. This information can be passed via _DSD method like::
+
+	Device (EEP0)
+	{
+		...
+		Name (_DSD, Package ()
+		{
+			ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+			Package ()
+			{
+				Package () { "size", 1024 },
+				Package () { "pagesize", 32 },
+				Package () { "address-width", 16 },
+			}
+		})
+	}
+
+Then the at25 SPI driver can get this configuration by calling device property
+APIs during ->probe() phase like::
+
+	err = device_property_read_u32(dev, "size", &size);
+	if (err)
+		...error handling...
+
+	err = device_property_read_u32(dev, "pagesize", &page_size);
+	if (err)
+		...error handling...
+
+	err = device_property_read_u32(dev, "address-width", &addr_width);
+	if (err)
+		...error handling...
+
+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::
+
+	static const struct acpi_device_id mpu3050_acpi_match[] = {
+		{ "MPU3050", 0 },
+		{ }
+	};
+	MODULE_DEVICE_TABLE(acpi, mpu3050_acpi_match);
+
+	static struct i2c_driver mpu3050_i2c_driver = {
+		.driver	= {
+			.name	= "mpu3050",
+			.pm	= &mpu3050_pm,
+			.of_match_table = mpu3050_of_match,
+			.acpi_match_table = mpu3050_acpi_match,
+		},
+		.probe		= mpu3050_probe,
+		.remove		= mpu3050_remove,
+		.id_table	= mpu3050_ids,
+	};
+	module_i2c_driver(mpu3050_i2c_driver);
+
+Reference to PWM device
+=======================
+
+Sometimes a device can be a consumer of PWM channel. Obviously OS would like
+to know which one. To provide this mapping the special property has been
+introduced, i.e.::
+
+    Device (DEV)
+    {
+        Name (_DSD, Package ()
+        {
+            ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+            Package () {
+                Package () { "compatible", Package () { "pwm-leds" } },
+                Package () { "label", "alarm-led" },
+                Package () { "pwms",
+                    Package () {
+                        "\\_SB.PCI0.PWM",  // <PWM device reference>
+                        0,                 // <PWM index>
+                        600000000,         // <PWM period>
+                        0,                 // <PWM flags>
+                    }
+                }
+            }
+        })
+        ...
+    }
+
+In the above example the PWM-based LED driver references to the PWM channel 0
+of \_SB.PCI0.PWM device with initial period setting equal to 600 ms (note that
+value is given in nanoseconds).
+
+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, PullNone, 0, 0, IoRestrictionOutputOnly,
+					"\\_SB.PCI0.GPI0", 0, ResourceConsumer) { 85 }
+
+				// Interrupt for the device
+				GpioInt (Edge, ActiveHigh, ExclusiveAndWake, PullNone, 0,
+					 "\\_SB.PCI0.GPI0", 0, ResourceConsumer) { 88 }
+			}
+
+			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 it is documented in
+Documentation/admin-guide/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/firmware-guide/acpi/gpio-properties.rst for more information
+about the _DSD binding related to GPIOs.
+
+RS-485 support
+==============
+
+ACPI _DSD (Device Specific Data) can be used to describe RS-485 capability
+of UART.
+
+For example::
+
+	Device (DEV)
+	{
+		...
+
+		// ACPI 5.1 _DSD used for RS-485 capabilities
+		Name (_DSD, Package ()
+		{
+			ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+			Package ()
+			{
+				Package () {"rs485-rts-active-low", Zero},
+				Package () {"rs485-rx-active-high", Zero},
+				Package () {"rs485-rx-during-tx", Zero},
+			}
+		})
+		...
+
+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:
+
+  - The children share the parent ACPI handle.
+  - 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 () { "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 Documentation/firmware-guide/acpi/DSD-properties-rules.rst for more
+information.
+
+PCI hierarchy representation
+============================
+
+Sometimes it could be useful to enumerate a PCI device, knowing its position on
+the PCI bus.
+
+For example, some systems use PCI devices soldered directly on the mother board,
+in a fixed position (ethernet, Wi-Fi, serial ports, etc.). In this conditions it
+is possible to refer to these PCI devices knowing their position on the PCI bus
+topology.
+
+To identify a PCI device, a complete hierarchical description is required, from
+the chipset root port to the final device, through all the intermediate
+bridges/switches of the board.
+
+For example, let's assume we have a system with a PCIe serial port, an
+Exar XR17V3521, soldered on the main board. This UART chip also includes
+16 GPIOs and we want to add the property ``gpio-line-names`` [1] to these pins.
+In this case, the ``lspci`` output for this component is::
+
+	07:00.0 Serial controller: Exar Corp. XR17V3521 Dual PCIe UART (rev 03)
+
+The complete ``lspci`` output (manually reduced in length) is::
+
+	00:00.0 Host bridge: Intel Corp... Host Bridge (rev 0d)
+	...
+	00:13.0 PCI bridge: Intel Corp... PCI Express Port A #1 (rev fd)
+	00:13.1 PCI bridge: Intel Corp... PCI Express Port A #2 (rev fd)
+	00:13.2 PCI bridge: Intel Corp... PCI Express Port A #3 (rev fd)
+	00:14.0 PCI bridge: Intel Corp... PCI Express Port B #1 (rev fd)
+	00:14.1 PCI bridge: Intel Corp... PCI Express Port B #2 (rev fd)
+	...
+	05:00.0 PCI bridge: Pericom Semiconductor Device 2404 (rev 05)
+	06:01.0 PCI bridge: Pericom Semiconductor Device 2404 (rev 05)
+	06:02.0 PCI bridge: Pericom Semiconductor Device 2404 (rev 05)
+	06:03.0 PCI bridge: Pericom Semiconductor Device 2404 (rev 05)
+	07:00.0 Serial controller: Exar Corp. XR17V3521 Dual PCIe UART (rev 03) <-- Exar
+	...
+
+The bus topology is::
+
+	-[0000:00]-+-00.0
+	           ...
+	           +-13.0-[01]----00.0
+	           +-13.1-[02]----00.0
+	           +-13.2-[03]--
+	           +-14.0-[04]----00.0
+	           +-14.1-[05-09]----00.0-[06-09]--+-01.0-[07]----00.0 <-- Exar
+	           |                               +-02.0-[08]----00.0
+	           |                               \-03.0-[09]--
+	           ...
+	           \-1f.1
+
+To describe this Exar device on the PCI bus, we must start from the ACPI name
+of the chipset bridge (also called "root port") with address::
+
+	Bus: 0 - Device: 14 - Function: 1
+
+To find this information, it is necessary to disassemble the BIOS ACPI tables,
+in particular the DSDT (see also [2])::
+
+	mkdir ~/tables/
+	cd ~/tables/
+	acpidump > acpidump
+	acpixtract -a acpidump
+	iasl -e ssdt?.* -d dsdt.dat
+
+Now, in the dsdt.dsl, we have to search the device whose address is related to
+0x14 (device) and 0x01 (function). In this case we can find the following
+device::
+
+	Scope (_SB.PCI0)
+	{
+	... other definitions follow ...
+		Device (RP02)
+		{
+			Method (_ADR, 0, NotSerialized)  // _ADR: Address
+			{
+				If ((RPA2 != Zero))
+				{
+					Return (RPA2) /* \RPA2 */
+				}
+				Else
+				{
+					Return (0x00140001)
+				}
+			}
+	... other definitions follow ...
+
+and the _ADR method [3] returns exactly the device/function couple that
+we are looking for. With this information and analyzing the above ``lspci``
+output (both the devices list and the devices tree), we can write the following
+ACPI description for the Exar PCIe UART, also adding the list of its GPIO line
+names::
+
+	Scope (_SB.PCI0.RP02)
+	{
+		Device (BRG1) //Bridge
+		{
+			Name (_ADR, 0x0000)
+
+			Device (BRG2) //Bridge
+			{
+				Name (_ADR, 0x00010000)
+
+				Device (EXAR)
+				{
+					Name (_ADR, 0x0000)
+
+					Name (_DSD, Package ()
+					{
+						ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+						Package ()
+						{
+							Package ()
+							{
+								"gpio-line-names",
+								Package ()
+								{
+									"mode_232",
+									"mode_422",
+									"mode_485",
+									"misc_1",
+									"misc_2",
+									"misc_3",
+									"",
+									"",
+									"aux_1",
+									"aux_2",
+									"aux_3",
+								}
+							}
+						}
+					})
+				}
+			}
+		}
+	}
+
+The location "_SB.PCI0.RP02" is obtained by the above investigation in the
+dsdt.dsl table, whereas the device names "BRG1", "BRG2" and "EXAR" are
+created analyzing the position of the Exar UART in the PCI bus topology.
+
+References
+==========
+
+[1] Documentation/firmware-guide/acpi/gpio-properties.rst
+
+[2] Documentation/admin-guide/acpi/initrd_table_override.rst
+
+[3] ACPI Specifications, Version 6.3 - Paragraph 6.1.1 _ADR Address)
+    https://uefi.org/sites/default/files/resources/ACPI_6_3_May16.pdf,
+    referenced 2020-11-18