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SubjectRe: [PATCH 6/6] gpio / ACPI: Add support for ACPI GPIO operation regions
Date
On Monday, February 24, 2014 06:00:11 PM Mika Westerberg wrote:
> GPIO operation regions is a new feature introduced in ACPI 5.0
> specification. This feature adds a way for platform ASL code to call back
> to OS GPIO driver and toggle GPIO pins.
>
> An example ASL code from Lenovo Miix 2 tablet with only relevant part
> listed:
>
> Device (\_SB.GPO0)
> {
> Name (AVBL, Zero)
> Method (_REG, 2, NotSerialized)
> {
> If (LEqual (Arg0, 0x08))
> {
> // Marks the region available
> Store (Arg1, AVBL)
> }
> }
>
> OperationRegion (GPOP, GeneralPurposeIo, Zero, 0x0C)
> Field (GPOP, ByteAcc, NoLock, Preserve)
> {
> Connection (
> GpioIo (Exclusive, PullDefault, 0, 0, IoRestrictionOutputOnly,
> "\\_SB.GPO0", 0x00, ResourceConsumer,,)
> {
> 0x003B
> }
> ),
> SHD3, 1,
> }
> }
>
> Device (SHUB)
> {
> Method (_PS0, 0, Serialized)
> {
> If (LEqual (\_SB.GPO0.AVBL, One))
> {
> Store (One, \_SB.GPO0.SHD3)
> Sleep (0x32)
> }
> }
> Method (_PS3, 0, Serialized)
> {
> If (LEqual (\_SB.GPO0.AVBL, One))
> {
> Store (Zero, \_SB.GPO0.SHD3)
> }
> }
> }
>
> The sensor hub (SHUB) device uses GPIO connection SHD3 to power the device
> whenever the GPIO operation region is available.

I would add more explanation of the ASL above here. Basically, how it is
supposed to work and what's the handler's role in it.

> Implement the support by registering GPIO operation region handlers for all
> GPIO devices that have an ACPI handle. First time the GPIO is used by the
> ASL code we make sure that the GPIO stays requested until the GPIO chip
> driver itself is unloaded. If we find out that the GPIO is already
> requested we just toggle it according to the value got from ASL code.

The patch itself looks good to me.

> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> ---
> drivers/gpio/gpiolib-acpi.c | 156 ++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 156 insertions(+)
>
> diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
> index 275735f390af..0133d38c447f 100644
> --- a/drivers/gpio/gpiolib-acpi.c
> +++ b/drivers/gpio/gpiolib-acpi.c
> @@ -16,6 +16,7 @@
> #include <linux/export.h>
> #include <linux/acpi.h>
> #include <linux/interrupt.h>
> +#include <linux/mutex.h>
>
> #include "gpiolib.h"
>
> @@ -26,7 +27,20 @@ struct acpi_gpio_event {
> unsigned int irq;
> };
>
> +struct acpi_gpio_connection {
> + struct list_head node;
> + struct gpio_desc *desc;
> +};
> +
> struct acpi_gpio_chip {
> + /*
> + * ACPICA requires that the first field of the context parameter
> + * passed to acpi_install_address_space_handler() is large enough
> + * to hold struct acpi_connection_info.
> + */
> + struct acpi_connection_info conn_info;
> + struct list_head conns;
> + struct mutex conn_lock;
> struct gpio_chip *chip;
> struct list_head events;
> };
> @@ -334,6 +348,146 @@ struct gpio_desc *acpi_get_gpiod_by_index(struct device *dev, int index,
> return lookup.desc ? lookup.desc : ERR_PTR(-ENOENT);
> }
>
> +static acpi_status
> +acpi_gpio_adr_space_handler(u32 function, acpi_physical_address address,
> + u32 bits, u64 *value, void *handler_context,
> + void *region_context)
> +{
> + struct acpi_gpio_chip *achip = region_context;
> + struct gpio_chip *chip = achip->chip;
> + struct acpi_resource_gpio *agpio;
> + struct acpi_resource *ares;
> + acpi_status status;
> + bool pull;
> + int i;
> +
> + status = acpi_buffer_to_resource(achip->conn_info.connection,
> + achip->conn_info.length, &ares);
> + if (ACPI_FAILURE(status))
> + return status;
> +
> + if (WARN_ON(ares->type != ACPI_RESOURCE_TYPE_GPIO)) {
> + ACPI_FREE(ares);
> + return AE_BAD_PARAMETER;
> + }
> +
> + agpio = &ares->data.gpio;
> + pull = agpio->pin_config == ACPI_PIN_CONFIG_PULLUP;
> +
> + if (WARN_ON(agpio->io_restriction == ACPI_IO_RESTRICT_INPUT &&
> + function == ACPI_WRITE)) {
> + ACPI_FREE(ares);
> + return AE_BAD_PARAMETER;
> + }
> +
> + for (i = 0; i < agpio->pin_table_length; i++) {
> + unsigned pin = agpio->pin_table[i];
> + struct acpi_gpio_connection *conn;
> + struct gpio_desc *desc;
> + bool found;
> +
> + desc = gpiochip_get_desc(chip, pin);
> + if (IS_ERR(desc)) {
> + status = AE_ERROR;
> + goto out;
> + }
> +
> + mutex_lock(&achip->conn_lock);
> +
> + found = false;
> + list_for_each_entry(conn, &achip->conns, node) {
> + if (conn->desc == desc) {
> + found = true;
> + break;
> + }
> + }
> + if (!found) {
> + int ret;
> +
> + ret = gpiochip_request_own_desc(desc, "ACPI:OpRegion");
> + if (ret) {
> + status = AE_ERROR;
> + mutex_unlock(&achip->conn_lock);
> + goto out;
> + }
> +
> + switch (agpio->io_restriction) {
> + case ACPI_IO_RESTRICT_INPUT:
> + gpiod_direction_input(desc);
> + break;
> + case ACPI_IO_RESTRICT_OUTPUT:
> + gpiod_direction_output(desc, pull);
> + break;
> + default:
> + /*
> + * Assume that the BIOS has configured the
> + * direction and pull accordingly.
> + */
> + break;
> + }
> +
> + conn = kzalloc(sizeof(*conn), GFP_KERNEL);
> + if (!conn) {
> + status = AE_NO_MEMORY;
> + mutex_unlock(&achip->conn_lock);
> + goto out;
> + }
> +
> + conn->desc = desc;
> +
> + list_add_tail(&conn->node, &achip->conns);
> + }
> +
> + mutex_unlock(&achip->conn_lock);
> +
> +
> + if (function == ACPI_WRITE)
> + gpiod_set_raw_value(desc, !!((1 << i) & *value));
> + else
> + *value |= gpiod_get_raw_value(desc) << i;
> + }
> +
> +out:
> + ACPI_FREE(ares);
> + return status;
> +}
> +
> +static void acpi_gpiochip_request_regions(struct acpi_gpio_chip *achip)
> +{
> + struct gpio_chip *chip = achip->chip;
> + acpi_handle handle = ACPI_HANDLE(chip->dev);
> + acpi_status status;
> +
> + INIT_LIST_HEAD(&achip->conns);
> + mutex_init(&achip->conn_lock);
> + status = acpi_install_address_space_handler(handle, ACPI_ADR_SPACE_GPIO,
> + acpi_gpio_adr_space_handler,
> + NULL, achip);
> + if (ACPI_FAILURE(status))
> + dev_err(chip->dev, "Failed to install GPIO OpRegion handler\n");
> +}
> +
> +static void acpi_gpiochip_free_regions(struct acpi_gpio_chip *achip)
> +{
> + struct gpio_chip *chip = achip->chip;
> + acpi_handle handle = ACPI_HANDLE(chip->dev);
> + struct acpi_gpio_connection *conn, *tmp;
> + acpi_status status;
> +
> + status = acpi_remove_address_space_handler(handle, ACPI_ADR_SPACE_GPIO,
> + acpi_gpio_adr_space_handler);
> + if (ACPI_FAILURE(status)) {
> + dev_err(chip->dev, "Failed to remove GPIO OpRegion handler\n");
> + return;
> + }
> +
> + list_for_each_entry_safe_reverse(conn, tmp, &achip->conns, node) {
> + gpiochip_free_own_desc(conn->desc);
> + list_del(&conn->node);
> + kfree(conn);
> + }
> +}
> +
> void acpi_gpiochip_add(struct gpio_chip *chip)
> {
> struct acpi_gpio_chip *achip;
> @@ -361,6 +515,7 @@ void acpi_gpiochip_add(struct gpio_chip *chip)
> }
>
> acpi_gpiochip_request_interrupts(achip);
> + acpi_gpiochip_request_regions(achip);
> }
>
> void acpi_gpiochip_remove(struct gpio_chip *chip)
> @@ -379,6 +534,7 @@ void acpi_gpiochip_remove(struct gpio_chip *chip)
> return;
> }
>
> + acpi_gpiochip_free_regions(achip);
> acpi_gpiochip_free_interrupts(achip);
>
> acpi_detach_data(handle, acpi_gpio_chip_dh);
>

--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.


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