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authorLance Ortiz <lance.ortiz@hp.com>2012-10-02 12:43:23 -0600
committerLen Brown <len.brown@intel.com>2012-10-06 15:52:16 -0400
commitd1efe3c324ead77d3f6cd85093b50f6bd2e17aba (patch)
tree7c85ab68cc0d906c0479e816d955481723e945b1
parent369d913b242cae2205471b11b6e33ac368ed33ec (diff)
downloadlinux-linaro-stable-d1efe3c324ead77d3f6cd85093b50f6bd2e17aba.tar.gz
ACPI: Add new sysfs interface to export device description
Add support to export the device description obtained from the ACPI _STR method, if one exists for a device, to user-space via a sysfs interface. This new interface provides a standard and platform neutral way for users to obtain the description text stored in the ACPI _STR method. If no _STR method exists for the device, no sysfs 'description' file will be created. The 'description' file will be located in the /sys/devices/ directory using the device's path. /sys/device/<bus>/<bridge path>/<device path>.../firmware_node/description Example: /sys/devices/pci0000:00/0000:00.07.0/0000:0e:00.0/firmware_node/description It can also be located using the ACPI device path, for example: /sys/devices/LNXSYSTM:00/device:00/ACPI0004:00/PNP0A08:00/device:13/device:15/description /sys/devices/LNXSYSTM:00/device:00/ACPI0004:00/ACPI0004:01/ACPI0007:02/description Execute the 'cat' command on the 'description' file to obtain the description string for that device. This patch also includes documentation describing how the new sysfs interface works Changes from v1-v2 based on comments by Len Brown and Fengguang Wu * Removed output "No Description" and leaving a NULL attribute if the _STR method failed to evaluate. * In acpi_device_remove_files() removed the redundent check of dev->pnp.str_obj before calling free. This check triggered a message from smatch. Signed-off-by: Lance Ortiz <lance.ortiz@hp.com> Signed-off-by: Len Brown <len.brown@intel.com>
-rw-r--r--Documentation/ABI/testing/sysfs-devices-firmware_node17
-rw-r--r--drivers/acpi/scan.c54
-rw-r--r--include/acpi/acpi_bus.h1
3 files changed, 70 insertions, 2 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-firmware_node b/Documentation/ABI/testing/sysfs-devices-firmware_node
new file mode 100644
index 000000000000..46badc9ea284
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-firmware_node
@@ -0,0 +1,17 @@
+What: /sys/devices/.../firmware_node/
+Date: September 2012
+Contact: <>
+Description:
+ The /sys/devices/.../firmware_node directory contains attributes
+ allowing the user space to check and modify some firmware
+ related properties of given device.
+
+What: /sys/devices/.../firmware_node/description
+Date: September 2012
+Contact: Lance Ortiz <lance.ortiz@hp.com>
+Description:
+ The /sys/devices/.../firmware/description attribute contains a string
+ that describes the device as provided by the _STR method in the ACPI
+ namespace. This attribute is read-only. If the device does not have
+ an _STR method associated with it in the ACPI namespace, this
+ attribute is not present.
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index d1ecca2b641a..04302835723d 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -10,6 +10,7 @@
#include <linux/signal.h>
#include <linux/kthread.h>
#include <linux/dmi.h>
+#include <linux/nls.h>
#include <acpi/acpi_drivers.h>
@@ -232,8 +233,35 @@ end:
}
static DEVICE_ATTR(path, 0444, acpi_device_path_show, NULL);
+/* sysfs file that shows description text from the ACPI _STR method */
+static ssize_t description_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf) {
+ struct acpi_device *acpi_dev = to_acpi_device(dev);
+ int result;
+
+ if (acpi_dev->pnp.str_obj == NULL)
+ return 0;
+
+ /*
+ * The _STR object contains a Unicode identifier for a device.
+ * We need to convert to utf-8 so it can be displayed.
+ */
+ result = utf16s_to_utf8s(
+ (wchar_t *)acpi_dev->pnp.str_obj->buffer.pointer,
+ acpi_dev->pnp.str_obj->buffer.length,
+ UTF16_LITTLE_ENDIAN, buf,
+ PAGE_SIZE);
+
+ buf[result++] = '\n';
+
+ return result;
+}
+static DEVICE_ATTR(description, 0444, description_show, NULL);
+
static int acpi_device_setup_files(struct acpi_device *dev)
{
+ struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
acpi_status status;
acpi_handle temp;
int result = 0;
@@ -257,6 +285,21 @@ static int acpi_device_setup_files(struct acpi_device *dev)
goto end;
}
+ /*
+ * If device has _STR, 'description' file is created
+ */
+ status = acpi_get_handle(dev->handle, "_STR", &temp);
+ if (ACPI_SUCCESS(status)) {
+ status = acpi_evaluate_object(dev->handle, "_STR",
+ NULL, &buffer);
+ if (ACPI_FAILURE(status))
+ buffer.pointer = NULL;
+ dev->pnp.str_obj = buffer.pointer;
+ result = device_create_file(&dev->dev, &dev_attr_description);
+ if (result)
+ goto end;
+ }
+
/*
* If device has _EJ0, 'eject' file is created that is used to trigger
* hot-removal function from userland.
@@ -274,8 +317,15 @@ static void acpi_device_remove_files(struct acpi_device *dev)
acpi_handle temp;
/*
- * If device has _EJ0, 'eject' file is created that is used to trigger
- * hot-removal function from userland.
+ * If device has _STR, remove 'description' file
+ */
+ status = acpi_get_handle(dev->handle, "_STR", &temp);
+ if (ACPI_SUCCESS(status)) {
+ kfree(dev->pnp.str_obj);
+ device_remove_file(&dev->dev, &dev_attr_description);
+ }
+ /*
+ * If device has _EJ0, remove 'eject' file.
*/
status = acpi_get_handle(dev->handle, "_EJ0", &temp);
if (ACPI_SUCCESS(status))
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index bde976ee068d..3eb9de318824 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -208,6 +208,7 @@ struct acpi_device_pnp {
struct list_head ids; /* _HID and _CIDs */
acpi_device_name device_name; /* Driver-determined */
acpi_device_class device_class; /* " */
+ union acpi_object *str_obj; /* unicode string for _STR method */
};
#define acpi_device_bid(d) ((d)->pnp.bus_id)