platform devices.
- 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).
+ are represented as struct spi_device or struct i2c_device. Note
+ that standard UARTs are not busses so there is no struct uart_device,
+ although some of them may be represented by sturct 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 and
-I2C), creates the physical devices and binds them to their ACPI handle in
-the ACPI namespace.
+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
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),
+ .acpi_match_table = mydrv_acpi_match,
},
};
Device (EEP0)
{
Name (_ADR, 1)
- Name (_CID, Package() {
+ Name (_CID, Package () {
"ATML0025",
"AT25",
})
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),
+ .acpi_match_table = 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::
+eeprom, etc. This information can be passed via _DSD method like::
Device (EEP0)
{
...
- Method (_DSM, 4, NotSerialized)
+ Name (_DSD, Package ()
{
- Store (Package (6)
+ ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+ Package ()
{
- "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;
+ Package () { "size", 1024 },
+ Package () { "pagesize", 32 },
+ Package () { "address-width", 16 },
+ }
+ })
+ }
- /* Fill in the input buffer */
+Then the at25 SPI driver can get this configuration by calling device property
+APIs during ->probe() phase like::
- status = acpi_evaluate_object(ACPI_HANDLE(&spi->dev), "_DSM",
- &input, &output);
- if (ACPI_FAILURE(status))
- /* Handle the error */
+ err = device_property_read_u32(dev, "size", &size);
+ if (err)
+ ...error handling...
- /* Extract the data here */
+ err = device_property_read_u32(dev, "pagesize", &page_size);
+ if (err)
+ ...error handling...
- kfree(output.pointer);
+ err = device_property_read_u32(dev, "address-width", &addr_width);
+ if (err)
+ ...error handling...
I2C serial bus support
======================
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),
+ .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
=======================
}
}
}
-
})
...
+ }
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
{
Name (SBUF, ResourceTemplate()
{
- ...
// Used to power on/off the device
- GpioIo (Exclusive, PullDefault, 0x0000, 0x0000,
- IoRestrictionOutputOnly, "\\_SB.PCI0.GPI0",
- 0x00, ResourceConsumer,,)
- {
- // Pin List
- 0x0055
- }
+ GpioIo (Exclusive, PullNone, 0, 0, IoRestrictionOutputOnly,
+ "\\_SB.PCI0.GPI0", 0, ResourceConsumer) { 85 }
// Interrupt for the device
- GpioInt (Edge, ActiveHigh, ExclusiveAndWake, PullNone,
- 0x0000, "\\_SB.PCI0.GPI0", 0x00, ResourceConsumer,,)
- {
- // Pin list
- 0x0058
- }
-
- ...
-
+ GpioInt (Edge, ActiveHigh, ExclusiveAndWake, PullNone, 0,
+ "\\_SB.PCI0.GPI0", 0, ResourceConsumer) { 88 }
}
Return (SBUF)
ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
Package ()
{
- Package () {"power-gpios", Package() {^DEV, 0, 0, 0 }},
- Package () {"irq-gpios", Package() {^DEV, 1, 0, 0 }},
+ 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
Device (TMP0)
{
Name (_HID, "PRP0001")
- Name (_DSD, Package() {
+ Name (_DSD, Package () {
ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
Package () {
- Package (2) { "compatible", "ti,tmp75" },
+ Package () { "compatible", "ti,tmp75" },
}
})
Method (_CRS, 0, Serialized)
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