[PATCH 3/3] platform/wmi: Expose the raw WDG data in sysfs

[Andy Lutomirski <luto@xxxxxxxxxx>]

This adds a sysfs binary attribute 'wdg' on the bus device
(i.e. /sys/class/wmi_bus/wmi_bus-*/wdg) that contains the raw _WDG
data from ACPI.  This can be used along with the wmi-bmof driver to
decode the raw interface data from ACPI.

There is very little new information here, as most of the contents
were already exposed in sysfs attributes on the wmi devices.

Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
---
 drivers/platform/x86/wmi.c | 63 ++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 61 insertions(+), 2 deletions(-)

diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
index 1a764e311e11..37ca56aa6025 100644
--- a/drivers/platform/x86/wmi.c
+++ b/drivers/platform/x86/wmi.c
@@ -76,6 +76,11 @@ struct wmi_block {
 	bool read_takes_no_args;
 };
 
+struct wmi_bus_priv {
+	union acpi_object *wdg_obj;
+	struct bin_attribute wdg_bin_attr;
+	bool wdg_bin_attr_created;
+};
 
 /*
  * If the GUID data block is marked as expensive, we must enable and
@@ -938,6 +943,7 @@ static bool guid_already_parsed(struct acpi_device *device,
  */
 static int parse_wdg(struct device *wmi_bus_dev, struct acpi_device *device)
 {
+	struct wmi_bus_priv *priv = dev_get_drvdata(wmi_bus_dev);
 	struct acpi_buffer out = {ACPI_ALLOCATE_BUFFER, NULL};
 	const struct guid_block *gblock;
 	struct wmi_block *wblock, *next;
@@ -1017,11 +1023,35 @@ static int parse_wdg(struct device *wmi_bus_dev, struct acpi_device *device)
 		}
 	}
 
+	priv->wdg_obj = obj;
+	return 0;
+
 out_free_pointer:
 	kfree(out.pointer);
 	return retval;
 }
 
+static ssize_t
+read_wdg(struct file *filp, struct kobject *kobj,
+	 struct bin_attribute *attr,
+	 char *buf, loff_t off, size_t count)
+{
+	struct wmi_bus_priv *priv =
+		container_of(attr, struct wmi_bus_priv, wdg_bin_attr);
+
+	if (off < 0)
+		return -EINVAL;
+
+	if (off >= priv->wdg_obj->buffer.length)
+		return 0;
+
+	if (count > priv->wdg_obj->buffer.length - off)
+		count = priv->wdg_obj->buffer.length - off;
+
+	memcpy(buf, priv->wdg_obj->buffer.pointer + off, count);
+	return count;
+}
+
 /*
  * WMI can have EmbeddedControl access regions. In which case, we just want to
  * hand these off to the EC driver.
@@ -1138,6 +1168,8 @@ static void acpi_wmi_notify_handler(acpi_handle handle, u32 event,
 
 static int acpi_wmi_remove(struct platform_device *device)
 {
+	struct device *wmi_bus_dev = dev_get_drvdata(&device->dev);
+	struct wmi_bus_priv *priv = dev_get_drvdata(wmi_bus_dev);
 	struct acpi_device *acpi_device = ACPI_COMPANION(&device->dev);
 
 	acpi_remove_notify_handler(acpi_device->handle, ACPI_DEVICE_NOTIFY,
@@ -1145,7 +1177,13 @@ static int acpi_wmi_remove(struct platform_device *device)
 	acpi_remove_address_space_handler(acpi_device->handle,
 				ACPI_ADR_SPACE_EC, &acpi_wmi_ec_space_handler);
 	wmi_free_devices(acpi_device);
-	device_unregister((struct device *)dev_get_drvdata(&device->dev));
+
+	if (priv->wdg_bin_attr_created)
+		sysfs_remove_bin_file(&wmi_bus_dev->kobj,
+				      &priv->wdg_bin_attr);
+	kfree(priv->wdg_obj);
+	kfree(priv);
+	device_unregister(wmi_bus_dev);
 
 	return 0;
 }
@@ -1154,6 +1192,7 @@ static int acpi_wmi_probe(struct platform_device *device)
 {
 	struct acpi_device *acpi_device;
 	struct device *wmi_bus_dev;
+	struct wmi_bus_priv *priv;
 	acpi_status status;
 	int error;
 
@@ -1190,14 +1229,34 @@ static int acpi_wmi_probe(struct platform_device *device)
 	}
 	dev_set_drvdata(&device->dev, wmi_bus_dev);
 
+	priv = kzalloc(sizeof(struct wmi_bus_priv), GFP_KERNEL);
+	if (!priv) {
+		error = -ENOMEM;
+		goto err_remove_busdev;
+	}
+	dev_set_drvdata(wmi_bus_dev, priv);
+
 	error = parse_wdg(wmi_bus_dev, acpi_device);
 	if (error) {
 		pr_err("Failed to parse WDG method\n");
-		goto err_remove_busdev;
+		goto err_free_priv;
 	}
 
+	sysfs_bin_attr_init(&priv->wdg_bin_attr);
+	priv->wdg_bin_attr.attr.name = "wdg";
+	priv->wdg_bin_attr.attr.mode = 0400;
+	priv->wdg_bin_attr.read = read_wdg;
+	priv->wdg_bin_attr.size = priv->wdg_obj->buffer.length;
+
+	/* A failure here isn't fatal. */
+	if (sysfs_create_bin_file(&wmi_bus_dev->kobj, &priv->wdg_bin_attr) == 0)
+		priv->wdg_bin_attr_created = true;
+
 	return 0;
 
+err_free_priv:
+	kfree(priv);
+
 err_remove_busdev:
 	device_unregister(wmi_bus_dev);
 
-- 
2.13.3