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Diffstat (limited to 'drivers/misc/ds1682.c')
-rw-r--r--drivers/misc/ds1682.c35
1 files changed, 26 insertions, 9 deletions
diff --git a/drivers/misc/ds1682.c b/drivers/misc/ds1682.c
index 7231260ac287..98a921ea9ee8 100644
--- a/drivers/misc/ds1682.c
+++ b/drivers/misc/ds1682.c
@@ -59,25 +59,42 @@ static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr,
{
struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
struct i2c_client *client = to_i2c_client(dev);
- __le32 val = 0;
+ unsigned long long val, check;
+ __le32 val_le = 0;
int rc;
dev_dbg(dev, "ds1682_show() called on %s\n", attr->attr.name);
/* Read the register */
rc = i2c_smbus_read_i2c_block_data(client, sattr->index, sattr->nr,
- (u8 *) & val);
+ (u8 *)&val_le);
if (rc < 0)
return -EIO;
- /* Special case: the 32 bit regs are time values with 1/4s
- * resolution, scale them up to milliseconds */
- if (sattr->nr == 4)
- return sprintf(buf, "%llu\n",
- ((unsigned long long)le32_to_cpu(val)) * 250);
+ val = le32_to_cpu(val_le);
+
+ if (sattr->index == DS1682_REG_ELAPSED) {
+ int retries = 5;
+
+ /* Detect and retry when a tick occurs mid-read */
+ do {
+ rc = i2c_smbus_read_i2c_block_data(client, sattr->index,
+ sattr->nr,
+ (u8 *)&val_le);
+ if (rc < 0 || retries <= 0)
+ return -EIO;
+
+ check = val;
+ val = le32_to_cpu(val_le);
+ retries--;
+ } while (val != check && val != (check + 1));
+ }
- /* Format the output string and return # of bytes */
- return sprintf(buf, "%li\n", (long)le32_to_cpu(val));
+ /* Format the output string and return # of bytes
+ * Special case: the 32 bit regs are time values with 1/4s
+ * resolution, scale them up to milliseconds
+ */
+ return sprintf(buf, "%llu\n", (sattr->nr == 4) ? (val * 250) : val);
}
static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr,