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rtc: tps65910: Add RTC calibration support
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.jaaskelainen@vaisala.com> Acked-by: Lee Jones <lee.jones@linaro.org> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
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@ -21,6 +21,7 @@
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#include <linux/types.h>
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#include <linux/types.h>
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#include <linux/rtc.h>
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#include <linux/rtc.h>
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#include <linux/bcd.h>
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#include <linux/bcd.h>
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#include <linux/math64.h>
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#include <linux/platform_device.h>
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#include <linux/platform_device.h>
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#include <linux/interrupt.h>
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#include <linux/interrupt.h>
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#include <linux/mfd/tps65910.h>
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#include <linux/mfd/tps65910.h>
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@ -33,6 +34,19 @@ struct tps65910_rtc {
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/* Total number of RTC registers needed to set time*/
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/* Total number of RTC registers needed to set time*/
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#define NUM_TIME_REGS (TPS65910_YEARS - TPS65910_SECONDS + 1)
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#define NUM_TIME_REGS (TPS65910_YEARS - TPS65910_SECONDS + 1)
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/* Total number of RTC registers needed to set compensation registers */
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#define NUM_COMP_REGS (TPS65910_RTC_COMP_MSB - TPS65910_RTC_COMP_LSB + 1)
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/* Min and max values supported with 'offset' interface (swapped sign) */
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#define MIN_OFFSET (-277761)
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#define MAX_OFFSET (277778)
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/* Number of ticks per hour */
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#define TICKS_PER_HOUR (32768 * 3600)
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/* Multiplier for ppb conversions */
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#define PPB_MULT (1000000000LL)
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static int tps65910_rtc_alarm_irq_enable(struct device *dev, unsigned enabled)
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static int tps65910_rtc_alarm_irq_enable(struct device *dev, unsigned enabled)
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{
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{
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struct tps65910 *tps = dev_get_drvdata(dev->parent);
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struct tps65910 *tps = dev_get_drvdata(dev->parent);
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@ -187,6 +201,133 @@ static int tps65910_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
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return ret;
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return ret;
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}
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}
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static int tps65910_rtc_set_calibration(struct device *dev, int calibration)
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{
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unsigned char comp_data[NUM_COMP_REGS];
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struct tps65910 *tps = dev_get_drvdata(dev->parent);
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s16 value;
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int ret;
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/*
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* TPS65910 uses two's complement 16 bit value for compensation for RTC
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* crystal inaccuracies. One time every hour when seconds counter
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* increments from 0 to 1 compensation value will be added to internal
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* RTC counter value.
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*
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* Compensation value 0x7FFF is prohibited value.
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*
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* Valid range for compensation value: [-32768 .. 32766]
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*/
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if ((calibration < -32768) || (calibration > 32766)) {
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dev_err(dev, "RTC calibration value out of range: %d\n",
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calibration);
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return -EINVAL;
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}
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value = (s16)calibration;
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comp_data[0] = (u16)value & 0xFF;
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comp_data[1] = ((u16)value >> 8) & 0xFF;
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/* Update all the compensation registers in one shot */
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ret = regmap_bulk_write(tps->regmap, TPS65910_RTC_COMP_LSB,
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comp_data, NUM_COMP_REGS);
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if (ret < 0) {
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dev_err(dev, "rtc_set_calibration error: %d\n", ret);
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return ret;
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}
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/* Enable automatic compensation */
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ret = regmap_update_bits(tps->regmap, TPS65910_RTC_CTRL,
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TPS65910_RTC_CTRL_AUTO_COMP, TPS65910_RTC_CTRL_AUTO_COMP);
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if (ret < 0)
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dev_err(dev, "auto_comp enable failed with error: %d\n", ret);
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return ret;
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}
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static int tps65910_rtc_get_calibration(struct device *dev, int *calibration)
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{
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unsigned char comp_data[NUM_COMP_REGS];
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struct tps65910 *tps = dev_get_drvdata(dev->parent);
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unsigned int ctrl;
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u16 value;
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int ret;
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ret = regmap_read(tps->regmap, TPS65910_RTC_CTRL, &ctrl);
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if (ret < 0)
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return ret;
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/* If automatic compensation is not enabled report back zero */
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if (!(ctrl & TPS65910_RTC_CTRL_AUTO_COMP)) {
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*calibration = 0;
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return 0;
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}
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ret = regmap_bulk_read(tps->regmap, TPS65910_RTC_COMP_LSB, comp_data,
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NUM_COMP_REGS);
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if (ret < 0) {
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dev_err(dev, "rtc_get_calibration error: %d\n", ret);
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return ret;
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}
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value = (u16)comp_data[0] | ((u16)comp_data[1] << 8);
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*calibration = (s16)value;
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return 0;
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}
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static int tps65910_read_offset(struct device *dev, long *offset)
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{
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int calibration;
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s64 tmp;
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int ret;
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ret = tps65910_rtc_get_calibration(dev, &calibration);
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if (ret < 0)
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return ret;
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/* Convert from RTC calibration register format to ppb format */
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tmp = calibration * (s64)PPB_MULT;
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if (tmp < 0)
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tmp -= TICKS_PER_HOUR / 2LL;
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else
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tmp += TICKS_PER_HOUR / 2LL;
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tmp = div_s64(tmp, TICKS_PER_HOUR);
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/* Offset value operates in negative way, so swap sign */
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*offset = (long)-tmp;
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return 0;
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}
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static int tps65910_set_offset(struct device *dev, long offset)
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{
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int calibration;
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s64 tmp;
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int ret;
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/* Make sure offset value is within supported range */
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if (offset < MIN_OFFSET || offset > MAX_OFFSET)
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return -ERANGE;
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/* Convert from ppb format to RTC calibration register format */
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tmp = offset * (s64)TICKS_PER_HOUR;
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if (tmp < 0)
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tmp -= PPB_MULT / 2LL;
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else
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tmp += PPB_MULT / 2LL;
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tmp = div_s64(tmp, PPB_MULT);
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/* Offset value operates in negative way, so swap sign */
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calibration = (int)-tmp;
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ret = tps65910_rtc_set_calibration(dev, calibration);
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return ret;
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}
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static irqreturn_t tps65910_rtc_interrupt(int irq, void *rtc)
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static irqreturn_t tps65910_rtc_interrupt(int irq, void *rtc)
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{
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{
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struct device *dev = rtc;
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struct device *dev = rtc;
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@ -219,6 +360,8 @@ static const struct rtc_class_ops tps65910_rtc_ops = {
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.read_alarm = tps65910_rtc_read_alarm,
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.read_alarm = tps65910_rtc_read_alarm,
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.set_alarm = tps65910_rtc_set_alarm,
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.set_alarm = tps65910_rtc_set_alarm,
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.alarm_irq_enable = tps65910_rtc_alarm_irq_enable,
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.alarm_irq_enable = tps65910_rtc_alarm_irq_enable,
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.read_offset = tps65910_read_offset,
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.set_offset = tps65910_set_offset,
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};
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};
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static int tps65910_rtc_probe(struct platform_device *pdev)
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static int tps65910_rtc_probe(struct platform_device *pdev)
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@ -134,6 +134,7 @@
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/* RTC_CTRL_REG bitfields */
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/* RTC_CTRL_REG bitfields */
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#define TPS65910_RTC_CTRL_STOP_RTC 0x01 /*0=stop, 1=run */
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#define TPS65910_RTC_CTRL_STOP_RTC 0x01 /*0=stop, 1=run */
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#define TPS65910_RTC_CTRL_AUTO_COMP 0x04
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#define TPS65910_RTC_CTRL_GET_TIME 0x40
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#define TPS65910_RTC_CTRL_GET_TIME 0x40
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/* RTC_STATUS_REG bitfields */
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/* RTC_STATUS_REG bitfields */
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