diff options
Diffstat (limited to 'drivers/rtc/rtc-tps65910.c')
| -rw-r--r-- | drivers/rtc/rtc-tps65910.c | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-tps65910.c b/drivers/rtc/rtc-tps65910.c index 5a3d53caa485..9dd1db9a12af 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 +201,133 @@ 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); + unsigned int ctrl; + u16 value; + int ret; + + ret = regmap_read(tps->regmap, TPS65910_RTC_CTRL, &ctrl); + if (ret < 0) + return ret; + + /* If automatic compensation is not enabled report back zero */ + if (!(ctrl & TPS65910_RTC_CTRL_AUTO_COMP)) { + *calibration = 0; + return 0; + } + + 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 +360,8 @@ 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) |