On Sat, 10 Dec 2016, Vesa Jääskeläinen wrote:
> Texas Instrument's TPS65910 has support for compensating RTC crystal
> inaccuracies. When enabled every hour RTC counter value will be compensated
> with two's complement value.
>
> Signed-off-by: Vesa Jääskeläinen <vesa.jaaskelai...@vaisala.com>
> ---
> drivers/rtc/rtc-tps65910.c | 132
> +++++++++++++++++++++++++++++++++++++++++++
> include/linux/mfd/tps65910.h | 1 +
For the MFD change:
Acked-by: Lee Jones <lee.jo...@linaro.org>
> 2 files changed, 133 insertions(+)
>
> diff --git a/drivers/rtc/rtc-tps65910.c b/drivers/rtc/rtc-tps65910.c
> index 5a3d53c..aafa716 100644
> --- a/drivers/rtc/rtc-tps65910.c
> +++ b/drivers/rtc/rtc-tps65910.c
> @@ -21,6 +21,7 @@
> #include <linux/types.h>
> #include <linux/rtc.h>
> #include <linux/bcd.h>
> +#include <linux/math64.h>
> #include <linux/platform_device.h>
> #include <linux/interrupt.h>
> #include <linux/mfd/tps65910.h>
> @@ -33,6 +34,19 @@ struct tps65910_rtc {
> /* Total number of RTC registers needed to set time*/
> #define NUM_TIME_REGS (TPS65910_YEARS - TPS65910_SECONDS + 1)
>
> +/* Total number of RTC registers needed to set compensation registers */
> +#define NUM_COMP_REGS (TPS65910_RTC_COMP_MSB - TPS65910_RTC_COMP_LSB
> + 1)
> +
> +/* Min and max values supported with 'offset' interface (swapped sign) */
> +#define MIN_OFFSET (-277761)
> +#define MAX_OFFSET (277778)
> +
> +/* Number of ticks per hour */
> +#define TICKS_PER_HOUR (32768 * 3600)
> +
> +/* Multiplier for ppb conversions */
> +#define PPB_MULT (1000000000LL)
> +
> static int tps65910_rtc_alarm_irq_enable(struct device *dev, unsigned
> enabled)
> {
> struct tps65910 *tps = dev_get_drvdata(dev->parent);
> @@ -187,6 +201,122 @@ static int tps65910_rtc_set_alarm(struct device *dev,
> struct rtc_wkalrm *alm)
> return ret;
> }
>
> +static int tps65910_rtc_set_calibration(struct device *dev, int calibration)
> +{
> + unsigned char comp_data[NUM_COMP_REGS];
> + struct tps65910 *tps = dev_get_drvdata(dev->parent);
> + s16 value;
> + int ret;
> +
> + /*
> + * TPS65910 uses two's complement 16 bit value for compensation for RTC
> + * crystal inaccuracies. One time every hour when seconds counter
> + * increments from 0 to 1 compensation value will be added to internal
> + * RTC counter value.
> + *
> + * Compensation value 0x7FFF is prohibited value.
> + *
> + * Valid range for compensation value: [-32768 .. 32766]
> + */
> + if ((calibration < -32768) || (calibration > 32766)) {
> + dev_err(dev, "RTC calibration value out of range: %d\n",
> + calibration);
> + return -EINVAL;
> + }
> +
> + value = (s16)calibration;
> +
> + comp_data[0] = (u16)value & 0xFF;
> + comp_data[1] = ((u16)value >> 8) & 0xFF;
> +
> + /* Update all the compensation registers in one shot */
> + ret = regmap_bulk_write(tps->regmap, TPS65910_RTC_COMP_LSB,
> + comp_data, NUM_COMP_REGS);
> + if (ret < 0) {
> + dev_err(dev, "rtc_set_calibration error: %d\n", ret);
> + return ret;
> + }
> +
> + /* Enable automatic compensation */
> + ret = regmap_update_bits(tps->regmap, TPS65910_RTC_CTRL,
> + TPS65910_RTC_CTRL_AUTO_COMP, TPS65910_RTC_CTRL_AUTO_COMP);
> + if (ret < 0)
> + dev_err(dev, "auto_comp enable failed with error: %d\n", ret);
> +
> + return ret;
> +}
> +
> +static int tps65910_rtc_get_calibration(struct device *dev, int *calibration)
> +{
> + unsigned char comp_data[NUM_COMP_REGS];
> + struct tps65910 *tps = dev_get_drvdata(dev->parent);
> + u16 value;
> + int ret;
> +
> + ret = regmap_bulk_read(tps->regmap, TPS65910_RTC_COMP_LSB, comp_data,
> + NUM_COMP_REGS);
> + if (ret < 0) {
> + dev_err(dev, "rtc_get_calibration error: %d\n", ret);
> + return ret;
> + }
> +
> + value = (u16)comp_data[0] | ((u16)comp_data[1] << 8);
> +
> + *calibration = (s16)value;
> +
> + return 0;
> +}
> +
> +static int tps65910_read_offset(struct device *dev, long *offset)
> +{
> + int calibration;
> + s64 tmp;
> + int ret;
> +
> + ret = tps65910_rtc_get_calibration(dev, &calibration);
> + if (ret < 0)
> + return ret;
> +
> + /* Convert from RTC calibration register format to ppb format */
> + tmp = calibration * (s64)PPB_MULT;
> + if (tmp < 0)
> + tmp -= TICKS_PER_HOUR / 2LL;
> + else
> + tmp += TICKS_PER_HOUR / 2LL;
> + tmp = div_s64(tmp, TICKS_PER_HOUR);
> +
> + /* Offset value operates in negative way, so swap sign */
> + *offset = (long)-tmp;
> +
> + return 0;
> +}
> +
> +static int tps65910_set_offset(struct device *dev, long offset)
> +{
> + int calibration;
> + s64 tmp;
> + int ret;
> +
> + /* Make sure offset value is within supported range */
> + if (offset < MIN_OFFSET || offset > MAX_OFFSET)
> + return -ERANGE;
> +
> + /* Convert from ppb format to RTC calibration register format */
> + tmp = offset * (s64)TICKS_PER_HOUR;
> + if (tmp < 0)
> + tmp -= PPB_MULT / 2LL;
> + else
> + tmp += PPB_MULT / 2LL;
> + tmp = div_s64(tmp, PPB_MULT);
> +
> + /* Offset value operates in negative way, so swap sign */
> + calibration = (int)-tmp;
> +
> + ret = tps65910_rtc_set_calibration(dev, calibration);
> +
> + return ret;
> +}
> +
> static irqreturn_t tps65910_rtc_interrupt(int irq, void *rtc)
> {
> struct device *dev = rtc;
> @@ -219,6 +349,8 @@ static const struct rtc_class_ops tps65910_rtc_ops = {
> .read_alarm = tps65910_rtc_read_alarm,
> .set_alarm = tps65910_rtc_set_alarm,
> .alarm_irq_enable = tps65910_rtc_alarm_irq_enable,
> + .read_offset = tps65910_read_offset,
> + .set_offset = tps65910_set_offset,
> };
>
> static int tps65910_rtc_probe(struct platform_device *pdev)
> diff --git a/include/linux/mfd/tps65910.h b/include/linux/mfd/tps65910.h
> index 6483a6f..ffb21e7 100644
> --- a/include/linux/mfd/tps65910.h
> +++ b/include/linux/mfd/tps65910.h
> @@ -134,6 +134,7 @@
>
> /* RTC_CTRL_REG bitfields */
> #define TPS65910_RTC_CTRL_STOP_RTC 0x01 /*0=stop, 1=run */
> +#define TPS65910_RTC_CTRL_AUTO_COMP 0x04
> #define TPS65910_RTC_CTRL_GET_TIME 0x40
>
> /* RTC_STATUS_REG bitfields */
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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