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Date: Fri, 7 Sep 2012 10:28:16 -0600
From: Lance Ortiz <lance.ortiz@...com>
To: rob@...dley.net, lenb@...nel.org
Cc: linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-acpi@...r.kernel.org, Lance Ortiz <lance.ortiz@...com>
Subject: [PATCH] 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
Signed-off-by: Lance Ortiz <lance.ortiz@...com>
---
.../ABI/testing/sysfs-devices-firmware_node | 17 ++++++
drivers/acpi/scan.c | 58 +++++++++++++++++++-
include/acpi/acpi_bus.h | 1 +
3 files changed, 74 insertions(+), 2 deletions(-)
create mode 100644 Documentation/ABI/testing/sysfs-devices-firmware_node
diff --git a/Documentation/ABI/testing/sysfs-devices-firmware_node b/Documentation/ABI/testing/sysfs-devices-firmware_node
new file mode 100644
index 0000000..46badc9
--- /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@...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 c8a1f3b..c9c91e1 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>
@@ -192,8 +193,38 @@ 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) {
+ result = sprintf(buf, "No Description\n");
+ goto end;
+ }
+
+ /*
+ * 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';
+
+end:
+ 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;
@@ -217,6 +248,21 @@ 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.
@@ -234,8 +280,16 @@ 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)) {
+ if (dev->pnp.str_obj != NULL)
+ 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 9e6e1c6..12172d5 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -209,6 +209,7 @@ 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)
--
1.7.7.6
--
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