diff options
Diffstat (limited to 'drivers/rtc/rtc-pcf8523.c')
| -rw-r--r-- | drivers/rtc/rtc-pcf8523.c | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-pcf8523.c b/drivers/rtc/rtc-pcf8523.c index 28c48b3c1946..c312af0db729 100644 --- a/drivers/rtc/rtc-pcf8523.c +++ b/drivers/rtc/rtc-pcf8523.c @@ -35,6 +35,9 @@ #define REG_MONTHS 0x08 #define REG_YEARS 0x09 +#define REG_OFFSET 0x0e +#define REG_OFFSET_MODE BIT(7) + struct pcf8523 { struct rtc_device *rtc; }; @@ -272,10 +275,47 @@ static int pcf8523_rtc_ioctl(struct device *dev, unsigned int cmd, #define pcf8523_rtc_ioctl NULL #endif +static int pcf8523_rtc_read_offset(struct device *dev, long *offset) +{ + struct i2c_client *client = to_i2c_client(dev); + int err; + u8 value; + s8 val; + + err = pcf8523_read(client, REG_OFFSET, &value); + if (err < 0) + return err; + + /* sign extend the 7-bit offset value */ + val = value << 1; + *offset = (value & REG_OFFSET_MODE ? 4069 : 4340) * (val >> 1); + + return 0; +} + +static int pcf8523_rtc_set_offset(struct device *dev, long offset) +{ + struct i2c_client *client = to_i2c_client(dev); + long reg_m0, reg_m1; + u8 value; + + reg_m0 = clamp(DIV_ROUND_CLOSEST(offset, 4340), -64L, 63L); + reg_m1 = clamp(DIV_ROUND_CLOSEST(offset, 4069), -64L, 63L); + + if (abs(reg_m0 * 4340 - offset) < abs(reg_m1 * 4069 - offset)) + value = reg_m0 & 0x7f; + else + value = (reg_m1 & 0x7f) | REG_OFFSET_MODE; + + return pcf8523_write(client, REG_OFFSET, value); +} + static const struct rtc_class_ops pcf8523_rtc_ops = { .read_time = pcf8523_rtc_read_time, .set_time = pcf8523_rtc_set_time, .ioctl = pcf8523_rtc_ioctl, + .read_offset = pcf8523_rtc_read_offset, + .set_offset = pcf8523_rtc_set_offset, }; static int pcf8523_probe(struct i2c_client *client, |