ACPI / scan: ACPI device object sysfs attribute for _STA evaluation

This patch adds a "status" attribute for an ACPI device. This status
attribute shows the value of the _STA object. The _STA object returns
current status of an ACPI device: enabled, disabled, functioning,
present.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
[rjw: Subject and changelog]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 32b340171d41..c0f57ff15024 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -602,6 +602,20 @@ acpi_device_sun_show(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR(sun, 0444, acpi_device_sun_show, NULL);
 
+static ssize_t status_show(struct device *dev, struct device_attribute *attr,
+                                char *buf) {
+        struct acpi_device *acpi_dev = to_acpi_device(dev);
+        acpi_status status;
+        unsigned long long sta;
+
+        status = acpi_evaluate_integer(acpi_dev->handle, "_STA", NULL, &sta);
+        if (ACPI_FAILURE(status))
+                return -ENODEV;
+
+        return sprintf(buf, "%llu\n", sta);
+}
+static DEVICE_ATTR_RO(status);
+
 static int acpi_device_setup_files(struct acpi_device *dev)
 {
         struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
@@ -657,6 +671,12 @@ static int acpi_device_setup_files(struct acpi_device *dev)
                 dev->pnp.sun = (unsigned long)-1;
         }
 
+        if (acpi_has_method(dev->handle, "_STA")) {
+                result = device_create_file(&dev->dev, &dev_attr_status);
+                if (result)
+                        goto end;
+        }
+
         /*
          * If device has _EJ0, 'eject' file is created that is used to trigger
          * hot-removal function from userland.
@@ -712,6 +732,8 @@ static void acpi_device_remove_files(struct acpi_device *dev)
                 device_remove_file(&dev->dev, &dev_attr_adr);
         device_remove_file(&dev->dev, &dev_attr_modalias);
         device_remove_file(&dev->dev, &dev_attr_hid);
+        if (acpi_has_method(dev->handle, "_STA"))
+                device_remove_file(&dev->dev, &dev_attr_status);
         if (dev->handle)
                 device_remove_file(&dev->dev, &dev_attr_path);
 }