lis3lv02d: proper power on sequence

Lis3 accelerometer sensors have quite long power on delay (up to 125
ms). This patch adds necessary delay to power on sequence for currently
supported lis3 chips.
Signed-off-by: Samu Onkalo <samu.p.onkalo@nokia.com>
Tested-by: Éric Piel <eric.piel@tremplin-utc.net>
Acked-by: Éric Piel <eric.piel@tremplin-utc.net>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/hwmon/lis3lv02d.c

@@ -50,6 +50,9 @@
  * joystick.
  */
 
+#define LIS3_PWRON_DELAY_WAI_12B	(5000)
+#define LIS3_PWRON_DELAY_WAI_8B		(3000)
+
 struct lis3lv02d lis3_dev = {
 	.misc_wait   = __WAIT_QUEUE_HEAD_INITIALIZER(lis3_dev.misc_wait),
 };
@@ -112,6 +115,24 @@ static void lis3lv02d_get_xyz(struct lis3lv02d *lis3, int *x, int *y, int *z)
 	*z = lis3lv02d_get_axis(lis3->ac.z, position);
 }
 
+/* conversion btw sampling rate and the register values */
+static int lis3_12_rates[4] = {40, 160, 640, 2560};
+static int lis3_8_rates[2] = {100, 400};
+
+static int lis3lv02d_get_odr(void)
+{
+	u8 ctrl;
+	int val;
+
+	lis3_dev.read(&lis3_dev, CTRL_REG1, &ctrl);
+
+	if (lis3_dev.whoami == WAI_12B)
+		val = lis3_12_rates[(ctrl & (CTRL1_DF0 | CTRL1_DF1)) >> 4];
+	else
+		val = lis3_8_rates[(ctrl & CTRL1_DR) >> 7];
+	return val;
+}
+
 void lis3lv02d_poweroff(struct lis3lv02d *lis3)
 {
 	/* disable X,Y,Z axis and power down */
@@ -125,6 +146,9 @@ void lis3lv02d_poweron(struct lis3lv02d *lis3)
 
 	lis3->init(lis3);
 
+	/* LIS3 power on delay is quite long */
+	msleep(lis3->pwron_delay / lis3lv02d_get_odr());
+
 	/*
 	 * Common configuration
 	 * BDU: (12 bits sensors only) LSB and MSB values are not updated until
@@ -364,23 +388,10 @@ static ssize_t lis3lv02d_calibrate_store(struct device *dev,
 	return count;
 }
 
-/* conversion btw sampling rate and the register values */
-static int lis3_12_rates[4] = {40, 160, 640, 2560};
-static int lis3_8_rates[2] = {100, 400};
 static ssize_t lis3lv02d_rate_show(struct device *dev,
 			struct device_attribute *attr, char *buf)
 {
-	u8 ctrl;
-	int val;
-
-	lis3_dev.read(&lis3_dev, CTRL_REG1, &ctrl);
-
-	if (lis3_dev.whoami == WAI_12B)
-		val = lis3_12_rates[(ctrl & (CTRL1_DF0 | CTRL1_DF1)) >> 4];
-	else
-		val = lis3_8_rates[(ctrl & CTRL1_DR) >> 7];
-
-	return sprintf(buf, "%d\n", val);
+	return sprintf(buf, "%d\n", lis3lv02d_get_odr());
 }
 
 static DEVICE_ATTR(position, S_IRUGO, lis3lv02d_position_show, NULL);
@@ -430,11 +441,13 @@ int lis3lv02d_init_device(struct lis3lv02d *dev)
 		printk(KERN_INFO DRIVER_NAME ": 12 bits sensor found\n");
 		dev->read_data = lis3lv02d_read_12;
 		dev->mdps_max_val = 2048;
+		dev->pwron_delay = LIS3_PWRON_DELAY_WAI_12B;
 		break;
 	case WAI_8B:
 		printk(KERN_INFO DRIVER_NAME ": 8 bits sensor found\n");
 		dev->read_data = lis3lv02d_read_8;
 		dev->mdps_max_val = 128;
+		dev->pwron_delay = LIS3_PWRON_DELAY_WAI_8B;
 		break;
 	default:
 		printk(KERN_ERR DRIVER_NAME

drivers/hwmon/lis3lv02d.h

@@ -202,6 +202,7 @@ struct lis3lv02d {
 	u8			whoami;    /* indicates measurement precision */
 	s16 (*read_data) (struct lis3lv02d *lis3, int reg);
 	int			mdps_max_val;
+	int			pwron_delay;
 
 	struct input_polled_dev	*idev;     /* input device */
 	struct platform_device	*pdev;     /* platform device */