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authorMika Westerberg <mika.westerberg@linux.intel.com>2014-03-14 19:58:07 +0400
committerLinus Walleij <linus.walleij@linaro.org>2014-03-14 20:25:02 +0400
commit473ed7be0da041275d57ab0bde1c21a6f23e637f (patch)
tree28b6085da8ad829a6453c91502d47a69f315046e /drivers/gpio
parenta176973ee83e561c0e4a9f3a2fcf6ab671e5e87b (diff)
downloadlinux-473ed7be0da041275d57ab0bde1c21a6f23e637f.tar.xz
gpio / ACPI: Add support for ACPI GPIO operation regions
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) } } } How this works is that whenever _PS0 or _PS3 method is run (typically when SHUB device is transitioned to D0 or D3 respectively), ASL code checks if the GPIO operation region is available (\_SB.GPO0.AVBL). If it is we go and store either 0 or 1 to \_SB.GPO0.SHD3. Now, when ACPICA notices ACPI GPIO operation region access (the store above) it will call acpi_gpio_adr_space_handler() that then toggles the GPIO accordingly using standard gpiolib interfaces. 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. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'drivers/gpio')
-rw-r--r--drivers/gpio/gpiolib-acpi.c163
1 files changed, 163 insertions, 0 deletions
diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index 092ea4e5c9a8..bf0f8b476696 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 +348,153 @@ 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_up;
+ 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_up = 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:
+ /*
+ * ACPI GPIO resources don't contain an
+ * initial value for the GPIO. Therefore we
+ * deduce that value from the pull field
+ * instead. If the pin is pulled up we
+ * assume default to be high, otherwise
+ * low.
+ */
+ gpiod_direction_output(desc, pull_up);
+ 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;
+ gpiochip_free_own_desc(desc);
+ 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 *acpi_gpio;
@@ -361,6 +522,7 @@ void acpi_gpiochip_add(struct gpio_chip *chip)
}
acpi_gpiochip_request_interrupts(acpi_gpio);
+ acpi_gpiochip_request_regions(acpi_gpio);
}
void acpi_gpiochip_remove(struct gpio_chip *chip)
@@ -379,6 +541,7 @@ void acpi_gpiochip_remove(struct gpio_chip *chip)
return;
}
+ acpi_gpiochip_free_regions(acpi_gpio);
acpi_gpiochip_free_interrupts(acpi_gpio);
acpi_detach_data(handle, acpi_gpio_chip_dh);