Messages in this thread | | | Subject | Re: [PATCH] rtc: rs5c372: add offset correction support | From | Camel Guo <> | Date | Tue, 30 Nov 2021 15:55:43 +0100 |
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On 11/30/21 10:50 AM, Camel Guo wrote: > From: Camel Guo <camelg@axis.com> > > This commit adds support of offset correction by configuring the > oscillation adjustment register of rs5c372. > > Signed-off-by: Camel Guo <camelg@axis.com> > --- > drivers/rtc/rtc-rs5c372.c | 80 +++++++++++++++++++++++++++++++++++++++ > 1 file changed, 80 insertions(+) > > diff --git a/drivers/rtc/rtc-rs5c372.c b/drivers/rtc/rtc-rs5c372.c > index 80980414890c..77027498cad5 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 RS5C372_TRIM_DEV (1 << 7) > +# define RS5C372_TRIM_DECR (1 << 6) > > #define RS5C_REG_ALARM_A_MIN 8 /* or ALARM_W */ > #define RS5C_REG_ALARM_A_HOURS 9 > @@ -485,6 +487,82 @@ static int rs5c372_rtc_proc(struct device *dev, > struct seq_file *seq) > #define rs5c372_rtc_proc NULL > #endif > > +static int rs5c372_read_offset(struct device *dev, long *offset) > +{ > + struct rs5c372 *rs5c = i2c_get_clientdata(to_i2c_client(dev)); > + int addr = RS5C_ADDR(RS5C372_REG_TRIM); > + unsigned char val = i2c_smbus_read_byte_data(rs5c->client, addr); > + long ppb_per_step = (val & RS5C372_TRIM_DEV) ? 1017 : 3052; > + unsigned char decr = val & RS5C372_TRIM_DECR; > + > + /* 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); > + unsigned char val = RS5C372_TRIM_DEV; > + long steps = 0; > + > + /* > + * 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) { > + /* > + * 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 3052 ppb. > + */ > + val &= ~RS5C372_TRIM_DEV; > + steps = DIV_ROUND_CLOSEST(offset, 3052); > + > + 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 > + * with the default values, which means no increment or > + * decrement. > + */ > + 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; > + } > + > + return 0; > +} > + > static const struct rtc_class_ops rs5c372_rtc_ops = { > .proc = rs5c372_rtc_proc, > .read_time = rs5c372_rtc_read_time, > @@ -492,6 +570,8 @@ static const struct rtc_class_ops rs5c372_rtc_ops = { > .read_alarm = rs5c_read_alarm, > .set_alarm = rs5c_set_alarm, > .alarm_irq_enable = rs5c_rtc_alarm_irq_enable, > + .read_offset = rs5c372_read_offset, > + .set_offset = rs5c372_set_offset, > }; > > #if IS_ENABLED(CONFIG_RTC_INTF_SYSFS) > -- > 2.20.1 >
Just realize that the oscillation adjustment registers of r2*, rs5c* are not totally same and all of these differences need to be handled in different way. Hence this patch needs to be updated to cover all cases.
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