[PATCH] lis3: Add axes module parameter for custom axis-mapping

[Takashi Iwai <tiwai@suse.de>]

The axis-mapping of lis3dev device on many (rather most) HP machines
doesn't follow the standard.  When each new model appears, users need
to adjust again.  Testing this requires the rebuild of kernel, thus
it's not trivial for end-users.

This patch adds a module parameter "axes" to allow a custom
axis-mapping without patching and recompiling the kernel driver.
User can pass the parameter such as axes=3,2,1.  Also it can be
changed via sysfs.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 drivers/hwmon/hp_accel.c  |    5 ++++-
 drivers/hwmon/lis3lv02d.c |   45 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 1 deletions(-)

diff --git a/drivers/hwmon/hp_accel.c b/drivers/hwmon/hp_accel.c
index 7580f55..3462a5d 100644
--- a/drivers/hwmon/hp_accel.c
+++ b/drivers/hwmon/hp_accel.c
@@ -297,7 +297,10 @@ static int lis3lv02d_add(struct acpi_device *device)
 	lis3lv02d_enum_resources(device);
 
 	/* If possible use a "standard" axes order */
-	if (dmi_check_system(lis3lv02d_dmi_ids) == 0) {
+	if (lis3_dev.ac.x && lis3_dev.ac.y && lis3_dev.ac.z) {
+		printk(KERN_INFO DRIVER_NAME ": Using custom axes %d,%d,%d\n",
+		       lis3_dev.ac.x, lis3_dev.ac.y, lis3_dev.ac.z);
+	} else if (dmi_check_system(lis3lv02d_dmi_ids) == 0) {
 		printk(KERN_INFO DRIVER_NAME ": laptop model unknown, "
 				 "using default axes configuration\n");
 		lis3_dev.ac = lis3lv02d_axis_normal;
diff --git a/drivers/hwmon/lis3lv02d.c b/drivers/hwmon/lis3lv02d.c
index 6138f03..4b179d5 100644
--- a/drivers/hwmon/lis3lv02d.c
+++ b/drivers/hwmon/lis3lv02d.c
@@ -75,6 +75,51 @@ struct lis3lv02d lis3_dev = {
 
 EXPORT_SYMBOL_GPL(lis3_dev);
 
+static int axis_array[3];
+static void copy_to_axis_array(void)
+{
+	axis_array[0] = lis3_dev.ac.x;
+	axis_array[1] = lis3_dev.ac.y;
+	axis_array[2] = lis3_dev.ac.z;
+}
+
+static void copy_from_axis_array(void)
+{
+	lis3_dev.ac.x = axis_array[0];
+	lis3_dev.ac.y = axis_array[1];
+	lis3_dev.ac.z = axis_array[2];
+}
+
+static int param_set_axis(const char *val, const struct kernel_param *kp)
+{
+	int ret;
+	copy_to_axis_array();
+	ret = param_set_int(val, kp);
+	if (!ret) {
+		int val = *(int *)kp->arg;
+		if (val < 0)
+			val = -val;
+		if (!val || val > 3)
+			return -EINVAL;
+		copy_from_axis_array();
+	}
+	return ret;
+}
+
+static int param_get_axis(char *buffer, const struct kernel_param *kp)
+{
+	copy_to_axis_array();
+	return param_get_int(buffer, kp);
+}
+
+static struct kernel_param_ops param_ops_axis = {
+	.set = param_set_axis,
+	.get = param_get_axis,
+};
+
+module_param_array_named(axes, axis_array, axis, NULL, 0644);
+MODULE_PARM_DESC(axes, "Axis-mapping for x,y,z directions");
+
 static s16 lis3lv02d_read_8(struct lis3lv02d *lis3, int reg)
 {
 	s8 lo;
-- 
1.7.2.1