Subject: [PATCH] [acpi video] Add helper for enumerating devices on the video bus

- Add enumerate_bus() and call from video_bus_init()
- Add helpers to assist that function
  - get_int_array() to get a list of ints from a package
  - get_package() to simply extract a package

Signed-off-by: Patrick Mochel <mochel@linux.intel.com>

---

 drivers/acpi/drivers/video/bus-device.c |   99 +++++++++++++++++++++++++++++++
 1 files changed, 99 insertions(+), 0 deletions(-)

applies-to: c3b9c5bc31cf92ab815f641fdcb534a2be680d18
f3d125468a74a1abd2eecd19fcdbc6a9eacae680
diff --git a/drivers/acpi/drivers/video/bus-device.c b/drivers/acpi/drivers/video/bus-device.c
index b7e48de..c9dbd7b 100644
--- a/drivers/acpi/drivers/video/bus-device.c
+++ b/drivers/acpi/drivers/video/bus-device.c
@@ -67,6 +67,71 @@ static int set_int(struct acpi_dev * ad,
 }
 
 
+static int get_package(struct acpi_dev * ad, char * method, 
+		       union acpi_object ** package)
+{
+	struct acpi_buffer buffer = {
+		.length		= ACPI_ALLOCATE_BUFFER,
+	};
+	union acpi_object * obj;
+	acpi_status status;
+
+	status = acpi_evaluate_object(ad->acpi_device->handle,
+				      method, NULL, &buffer);
+	if (ACPI_FAILURE(status)) {
+		err("Evaluating %s", method);
+		return -ENODEV;
+	}
+
+	obj = buffer.pointer;
+	if (!(obj && obj->type == ACPI_TYPE_PACKAGE)) {
+		err("Invalid %s data", method);
+		kfree(buffer.pointer);
+		return -EFAULT;
+	}
+	*package = obj;
+	return 0;
+}
+
+static int get_int_array(struct acpi_dev * ad, char * method, 
+			 u32 * values, u32 * num)
+{
+	union acpi_object * package;
+	int ret;
+	int i;
+
+	/*
+	 * Get the package from the namespace
+	 */
+	ret = get_package(ad, method, &package);
+	if (ret)
+		return ret;
+
+	/*
+	 * Modify the count, based on passed limits
+	 */
+	if (package->package.count <= *num)
+		*num = package->package.count;
+	else
+		err("Ignoring elements from %s: Have room for %d, need %d",
+		    method, *num, package->package.count);
+
+	/*
+	 * Fill the array with the package contents
+	 */
+	for (i = 0; i < *num; i++) {
+		union acpi_object * o = &package->package.elements[i];
+
+		if (o->type != ACPI_TYPE_INTEGER) {
+			err("Invalid %s data at [%d]", method, i);
+		}
+		values[i] = o->integer.value;
+	}
+	kfree(package);
+	return 0;
+}
+
+
 /**
  *	can_switch - Check if a video bus supports video switching
  *	@ad:	The ACPI device representing the video bus
@@ -254,6 +319,36 @@ static int get_post_info(struct acpi_vid
 }
 
 
+/**
+ *	enumerate_bus - Discover and count video devices for a bus
+ *	@vb:	The ACPI video bus
+ *
+ *
+ *	NOTE: The ACPI spec implies that a maximum of 8 devices can be
+ *	attached to a video bus (based on the fact that they reserve 
+ *	3 bits for the "head/pipe ID" field in the video device attribute.
+ *	Having 8 attached displays seems unlikely in 2006, but it is a 
+ *	hard-coded limit in the future when we all have 64 monitors plugged
+ *	into our laptops..
+ */
+
+static int enumerate_bus(struct acpi_video_bus * vb)
+{
+	u32 dod_values[VIDEO_DEVICE_MAX];
+	int ret;
+	int i;
+
+	ret = get_int_array(vb->v_ad, "_DOD", dod_values, &vb->v_dev_num);
+	if (ret)
+		return ret;
+
+	dbg("Found %d video heads in _DOD", vb->v_dev_num);
+
+	for (i = 0; i < vb->v_dev_num; i++)
+		vb->v_dev[i].v_attrib = dod_values[i];
+	return 0;
+}
+
 int video_bus_init(struct acpi_video_bus * vb)
 {
 	int ret = 0;
@@ -279,6 +374,10 @@ int video_bus_init(struct acpi_video_bus
 			return ret;
 	}
 
+	if (vb->v_can_switch) {
+		ret = enumerate_bus(vb);
+	}
+
 	return ret;
 }
 
---
0.99.9.GIT