Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

[linux.git] / drivers / misc / ds1682.c

diff --git a/drivers/misc/ds1682.c b/drivers/misc/ds1682.c
index 0fc5366457b9861eaaa3d828cafd573dd5803e2b..98a921ea9ee898e6ad8cf7ac01b15545c0229590 100644 (file)
--- a/drivers/misc/ds1682.c
+++ b/drivers/misc/ds1682.c
@@ -59,7 +59,7 @@ 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);
-       unsigned long long val;
+       unsigned long long val, check;
        __le32 val_le = 0;
        int rc;
 
@@ -73,6 +73,23 @@ static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr,
 
        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
         * Special case: the 32 bit regs are time values with 1/4s
         * resolution, scale them up to milliseconds