hp accelerometer: add freefall detection

This adds freefall handling to hp_accel driver.  According to HP, it
should just work, without us having to set the chip up by hand.

hpfall.c is example .c program that parks the disk when accelerometer
detects free fall.  It should work; for now, it uses fixed 20seconds
protection period.

Signed-off-by: Pavel Machek <pavel@suse.cz>
Cc: Thomas Renninger <trenn@suse.de>
Cc: Éric Piel <eric.piel@tremplin-utc.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 27 insertions, 0 deletions

diff --git a/drivers/hwmon/hp_accel.c b/drivers/hwmon/hp_accel.c
index abf4dfc8ec2..dcefe1d2adb 100644
--- a/drivers/hwmon/hp_accel.c
+++ b/drivers/hwmon/hp_accel.c
@@ -213,6 +213,30 @@ static struct delayed_led_classdev hpled_led = {
 	.set_brightness = hpled_set,
 };
 
+static acpi_status
+lis3lv02d_get_resource(struct acpi_resource *resource, void *context)
+{
+	if (resource->type == ACPI_RESOURCE_TYPE_EXTENDED_IRQ) {
+		struct acpi_resource_extended_irq *irq;
+		u32 *device_irq = context;
+
+		irq = &resource->data.extended_irq;
+		*device_irq = irq->interrupts[0];
+	}
+
+	return AE_OK;
+}
+
+static void lis3lv02d_enum_resources(struct acpi_device *device)
+{
+	acpi_status status;
+
+	status = acpi_walk_resources(device->handle, METHOD_NAME__CRS,
+					lis3lv02d_get_resource, &adev.irq);
+	if (ACPI_FAILURE(status))
+		printk(KERN_DEBUG DRIVER_NAME ": Error getting resources\n");
+}
+
 static int lis3lv02d_add(struct acpi_device *device)
 {
 	u8 val;
@@ -247,6 +271,9 @@ static int lis3lv02d_add(struct acpi_device *device)
 	if (ret)
 		return ret;
 
+	/* obtain IRQ number of our device from ACPI */
+	lis3lv02d_enum_resources(adev.device);
+
 	ret = lis3lv02d_init_device(&adev);
 	if (ret) {
 		flush_work(&hpled_led.work);