diff options
Diffstat (limited to 'drivers/misc/ds1682.c')
| -rw-r--r-- | drivers/misc/ds1682.c | 35 |
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, |