diff options
Diffstat (limited to 'drivers/rtc/rtc-rs5c372.c')
| -rw-r--r-- | drivers/rtc/rtc-rs5c372.c | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-rs5c372.c b/drivers/rtc/rtc-rs5c372.c index 955513514179..b3155fa914f1 100644 --- a/drivers/rtc/rtc-rs5c372.c +++ b/drivers/rtc/rtc-rs5c372.c @@ -30,6 +30,8 @@ #define RS5C372_REG_TRIM 7 # define RS5C372_TRIM_XSL 0x80 # define RS5C372_TRIM_MASK 0x7F +# define R2221TL_TRIM_DEV (1 << 7) /* only if R2221TL */ +# define RS5C372_TRIM_DECR (1 << 6) #define RS5C_REG_ALARM_A_MIN 8 /* or ALARM_W */ #define RS5C_REG_ALARM_A_HOURS 9 @@ -539,6 +541,122 @@ static int rs5c372_ioctl(struct device *dev, unsigned int cmd, unsigned long arg #define rs5c372_ioctl NULL #endif +static int rs5c372_read_offset(struct device *dev, long *offset) +{ + struct rs5c372 *rs5c = i2c_get_clientdata(to_i2c_client(dev)); + u8 val = rs5c->regs[RS5C372_REG_TRIM]; + long ppb_per_step = 0; + bool decr = val & RS5C372_TRIM_DECR; + + switch (rs5c->type) { + case rtc_r2221tl: + ppb_per_step = val & R2221TL_TRIM_DEV ? 1017 : 3051; + break; + case rtc_rs5c372a: + case rtc_rs5c372b: + ppb_per_step = val & RS5C372_TRIM_XSL ? 3125 : 3051; + break; + default: + ppb_per_step = 3051; + break; + } + + /* Only bits[0:5] repsents the time counts */ + val &= 0x3F; + + /* If bits[1:5] are all 0, it means no increment or decrement */ + if (!(val & 0x3E)) { + *offset = 0; + } else { + if (decr) + *offset = -(((~val) & 0x3F) + 1) * ppb_per_step; + else + *offset = (val - 1) * ppb_per_step; + } + + return 0; +} + +static int rs5c372_set_offset(struct device *dev, long offset) +{ + struct rs5c372 *rs5c = i2c_get_clientdata(to_i2c_client(dev)); + int addr = RS5C_ADDR(RS5C372_REG_TRIM); + u8 val = 0; + u8 tmp = 0; + long ppb_per_step = 3051; + long steps = LONG_MIN; + + switch (rs5c->type) { + case rtc_rs5c372a: + case rtc_rs5c372b: + tmp = rs5c->regs[RS5C372_REG_TRIM]; + if (tmp & RS5C372_TRIM_XSL) { + ppb_per_step = 3125; + val |= RS5C372_TRIM_XSL; + } + break; + case rtc_r2221tl: + /* + * Check if it is possible to use high resolution mode (DEV=1). + * In this mode, the minimum resolution is 2 / (32768 * 20 * 3), + * which is about 1017 ppb. + */ + steps = DIV_ROUND_CLOSEST(offset, 1017); + if (steps >= -0x3E && steps <= 0x3E) { + ppb_per_step = 1017; + val |= R2221TL_TRIM_DEV; + } else { + /* + * offset is out of the range of high resolution mode. + * Try to use low resolution mode (DEV=0). In this mode, + * the minimum resolution is 2 / (32768 * 20), which is + * about 3051 ppb. + */ + steps = LONG_MIN; + } + break; + default: + break; + } + + if (steps == LONG_MIN) { + steps = DIV_ROUND_CLOSEST(offset, ppb_per_step); + if (steps > 0x3E || steps < -0x3E) + return -ERANGE; + } + + if (steps > 0) { + val |= steps + 1; + } else { + val |= RS5C372_TRIM_DECR; + val |= (~(-steps - 1)) & 0x3F; + } + + if (!steps || !(val & 0x3E)) { + /* + * if offset is too small, set oscillation adjustment register + * or time trimming register with its default value whic means + * no increment or decrement. But for rs5c372[a|b], the XSL bit + * should be kept unchanged. + */ + if (rs5c->type == rtc_rs5c372a || rs5c->type == rtc_rs5c372b) + val &= RS5C372_TRIM_XSL; + else + val = 0; + } + + dev_dbg(&rs5c->client->dev, "write 0x%x for offset %ld\n", val, offset); + + if (i2c_smbus_write_byte_data(rs5c->client, addr, val) < 0) { + dev_err(&rs5c->client->dev, "failed to write 0x%x to reg %d\n", val, addr); + return -EIO; + } + + rs5c->regs[RS5C372_REG_TRIM] = val; + + return 0; +} + static const struct rtc_class_ops rs5c372_rtc_ops = { .proc = rs5c372_rtc_proc, .read_time = rs5c372_rtc_read_time, @@ -547,6 +665,8 @@ static const struct rtc_class_ops rs5c372_rtc_ops = { .set_alarm = rs5c_set_alarm, .alarm_irq_enable = rs5c_rtc_alarm_irq_enable, .ioctl = rs5c372_ioctl, + .read_offset = rs5c372_read_offset, + .set_offset = rs5c372_set_offset, }; #if IS_ENABLED(CONFIG_RTC_INTF_SYSFS) |