lis3: sysfs entry for setting chip measurement rate

It is possible to read position information at the chip measurement rate
via sysfs.  This patch adds possibility to configure chip measurement
rate.
Signed-off-by: Samu Onkalo <samu.p.onkalo@nokia.com>
Signed-off-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

@@ -121,18 +121,35 @@ static void lis3lv02d_get_xyz(struct lis3lv02d *lis3, int *x, int *y, int *z)
 static int lis3_12_rates[4] = {40, 160, 640, 2560};
 static int lis3_8_rates[2] = {100, 400};
 
+/* ODR is Output Data Rate */
 static int lis3lv02d_get_odr(void)
 {
 	u8 ctrl;
-	int val;
+	int shift;
 
 	lis3_dev.read(&lis3_dev, CTRL_REG1, &ctrl);
+	ctrl &= lis3_dev.odr_mask;
+	shift = ffs(lis3_dev.odr_mask) - 1;
+	return lis3_dev.odrs[(ctrl >> shift)];
+}
 
-	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;
+static int lis3lv02d_set_odr(int rate)
+{
+	u8 ctrl;
+	int i, len, shift;
+
+	lis3_dev.read(&lis3_dev, CTRL_REG1, &ctrl);
+	ctrl &= ~lis3_dev.odr_mask;
+	len = 1 << hweight_long(lis3_dev.odr_mask); /* # of possible values */
+	shift = ffs(lis3_dev.odr_mask) - 1;
+
+	for (i = 0; i < len; i++)
+		if (lis3_dev.odrs[i] == rate) {
+			lis3_dev.write(&lis3_dev, CTRL_REG1,
+					ctrl | (i << shift));
+			return 0;
+		}
+	return -EINVAL;
 }
 
 static int lis3lv02d_selftest(struct lis3lv02d *lis3, s16 results[3])
@@ -433,9 +450,25 @@ static ssize_t lis3lv02d_rate_show(struct device *dev,
 	return sprintf(buf, "%d\n", lis3lv02d_get_odr());
 }
 
+static ssize_t lis3lv02d_rate_set(struct device *dev,
+				struct device_attribute *attr, const char *buf,
+				size_t count)
+{
+	unsigned long rate;
+
+	if (strict_strtoul(buf, 0, &rate))
+		return -EINVAL;
+
+	if (lis3lv02d_set_odr(rate))
+		return -EINVAL;
+
+	return count;
+}
+
 static DEVICE_ATTR(selftest, S_IRUSR, lis3lv02d_selftest_show, NULL);
 static DEVICE_ATTR(position, S_IRUGO, lis3lv02d_position_show, NULL);
-static DEVICE_ATTR(rate, S_IRUGO, lis3lv02d_rate_show, NULL);
+static DEVICE_ATTR(rate, S_IRUGO | S_IWUSR, lis3lv02d_rate_show,
+					    lis3lv02d_rate_set);
 
 static struct attribute *lis3lv02d_attributes[] = {
 	&dev_attr_selftest.attr,
@@ -480,12 +513,16 @@ int lis3lv02d_init_device(struct lis3lv02d *dev)
 		dev->read_data = lis3lv02d_read_12;
 		dev->mdps_max_val = 2048;
 		dev->pwron_delay = LIS3_PWRON_DELAY_WAI_12B;
+		dev->odrs = lis3_12_rates;
+		dev->odr_mask = CTRL1_DF0 | CTRL1_DF1;
 		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;
+		dev->odrs = lis3_8_rates;
+		dev->odr_mask = CTRL1_DR;
 		break;
 	default:
 		printk(KERN_ERR DRIVER_NAME

drivers/hwmon/lis3lv02d.h

@@ -208,6 +208,8 @@ struct lis3lv02d {
 	int (*write) (struct lis3lv02d *lis3, int reg, u8 val);
 	int (*read) (struct lis3lv02d *lis3, int reg, u8 *ret);
 
+	int                     *odrs;     /* Supported output data rates */
+	u8                      odr_mask;  /* ODR bit mask */
 	u8			whoami;    /* indicates measurement precision */
 	s16 (*read_data) (struct lis3lv02d *lis3, int reg);
 	int			mdps_max_val;