From: Chris Verges <kg4ysn@xxxxxxxxx>
The LM73 sensor supports four resolutions (11-bit to 14-bit). The
number of bits used are controlled via the control/status register on
the LM73. This patch adds a sysfs interface to manipulate the
appropriate bits in the control/status register.
Example usage:
# set resolution to 11-bit (default)
echo "11" > /sys/class/hwmon/hwmon0/device/temp1_resolution
# set resolution to 14-bit
echo "14" > /sys/class/hwmon/hwmon0/device/temp1_resolution
# read current resolution
cat /sys/class/hwmon/hwmon0/device/temp1_resolution
Signed-off-by: Chris Verges <kg4ysn@xxxxxxxxx>
---
drivers/hwmon/lm73.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 58 insertions(+), 2 deletions(-)
diff --git a/drivers/hwmon/lm73.c b/drivers/hwmon/lm73.c
index 9e64d96..e9fb992 100644
--- a/drivers/hwmon/lm73.c
+++ b/drivers/hwmon/lm73.c
@@ -73,6 +73,61 @@ static ssize_t show_temp(struct device *dev, struct device_attribute *da,
return sprintf(buf, "%d\n", temp);
}
+static ssize_t set_resolution(struct device *dev,
+ struct device_attribute *da, const char *buf,
+ size_t count)
+{
+ struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+ struct i2c_client *client = to_i2c_client(dev);
+ long value;
+ int reg = strict_strtol(buf, 10, &value);
+ if (reg < 0)
+ return reg;
+
+ if (value < 11 || value > 14)
+ return -EINVAL;
+
+ /* Read the current control/status register */
+ reg = i2c_smbus_read_byte_data(client, attr->index);
+ if (reg < 0)
+ return -EIO;
+
+ reg &= 0x7F; /* Remove all non-essential bits */
+
+ /*
+ * Control/Status register bit description:
+ *
+ * D[7] Time-Out Disable
+ * D[6:5] Temperature Resolution
+ * 00: 0.25 C/LSB
+ * 01: 0.125 C/LSB
+ * 10: 0.0625 C/LSB
+ * 11: 0.03125 C/LSB
+ * D[4] Reserved
+ * D[3] Alert Pin Status
+ * D[2] Temperature High Flag
+ * D[1] Temperature Low Flag
+ * D[0] Data Available Flag
+ */
+
+ /* Convert the resolution from the integer value to the bitmask */
+ value -= 11;
+ value <<= 5;
+ value |= reg;
+
+ /* Write the new control/status register value */
+ i2c_smbus_write_byte_data(client, attr->index, value);
+ return count;
+}
+
+static ssize_t show_resolution(struct device *dev, struct device_attribute *da,
+ char *buf)
+{
+ struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+ struct i2c_client *client = to_i2c_client(dev);
+ int value = i2c_smbus_read_byte_data(client, attr->index);
+ return sprintf(buf, "%d\n", value);
+}
/*-----------------------------------------------------------------------*/
@@ -84,13 +139,14 @@ static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO,
show_temp, set_temp, LM73_REG_MIN);
static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
show_temp, NULL, LM73_REG_INPUT);
-
+static SENSOR_DEVICE_ATTR(temp1_resolution, S_IWUSR | S_IRUGO,
+ show_resolution, set_resolution, LM73_REG_CTRL);
static struct attribute *lm73_attributes[] = {
&sensor_dev_attr_temp1_input.dev_attr.attr,
&sensor_dev_attr_temp1_max.dev_attr.attr,
&sensor_dev_attr_temp1_min.dev_attr.attr,
-
+ &sensor_dev_attr_temp1_resolution.dev_attr.attr,
NULL
};
--
1.7.4.1
>From 171bd4d58d5e9ded28bf3d105a714c6d9486927b Mon Sep 17 00:00:00 2001
From: Chris Verges <kg4ysn@xxxxxxxxx>
Date: Fri, 23 Dec 2011 02:10:27 -0800
Subject: [PATCH 2/2] Replaced strict_strtol with kstrtol in lm73 set_resolution()
Signed-off-by: Chris Verges <kg4ysn@xxxxxxxxx>
---
drivers/hwmon/lm73.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/drivers/hwmon/lm73.c b/drivers/hwmon/lm73.c
index e9fb992..ca1eff1 100644
--- a/drivers/hwmon/lm73.c
+++ b/drivers/hwmon/lm73.c
@@ -80,7 +80,7 @@ static ssize_t set_resolution(struct device *dev,
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
struct i2c_client *client = to_i2c_client(dev);
long value;
- int reg = strict_strtol(buf, 10, &value);
+ int reg = kstrtol(buf, 10, &value);
if (reg < 0)
return reg;
--
1.7.4.1
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