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linux/drivers/rtc/rtc-tps6594.c
Esteban Blanc 9f67c1e639 rtc: tps6594: Add driver for TPS6594 RTC 
TPS6594 PMIC is a MFD. This patch adds support for
the RTC found inside TPS6594 family of PMIC.

Alarm is also supported.

Signed-off-by: Esteban Blanc <eblanc@baylibre.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Tested-by: Thomas Richard <thomas.richard@bootlin.com>
Link: https://lore.kernel.org/r/20231107094701.2223486-1-eblanc@baylibre.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2024-01-08 01:12:16 +01:00

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// SPDX-License-Identifier: GPL-2.0
/*
* RTC driver for tps6594 PMIC
*
* Copyright (C) 2023 BayLibre Incorporated - https://www.baylibre.com/
*/
#include <linux/bcd.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/limits.h>
#include <linux/math64.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/mod_devicetable.h>
#include <linux/property.h>
#include <linux/rtc.h>
#include <linux/types.h>
#include <linux/units.h>
#include <linux/mfd/tps6594.h>
// Total number of RTC registers needed to set time
#define NUM_TIME_REGS (TPS6594_REG_RTC_WEEKS - TPS6594_REG_RTC_SECONDS + 1)
// Total number of RTC alarm registers
#define NUM_TIME_ALARM_REGS (NUM_TIME_REGS - 1)
/*
* Min and max values supported by 'offset' interface (swapped sign).
* After conversion, the values do not exceed the range [-32767, 33767]
* which COMP_REG must conform to.
*/
#define MIN_OFFSET (-277774)
#define MAX_OFFSET (277774)
// Number of ticks per hour
#define TICKS_PER_HOUR (32768 * 3600)
// Multiplier for ppb conversions
#define PPB_MULT NANO
static int tps6594_rtc_alarm_irq_enable(struct device *dev,
unsigned int enabled)
{
struct tps6594 *tps = dev_get_drvdata(dev->parent);
u8 val;
val = enabled ? TPS6594_BIT_IT_ALARM : 0;
return regmap_update_bits(tps->regmap, TPS6594_REG_RTC_INTERRUPTS,
TPS6594_BIT_IT_ALARM, val);
}
/* Pulse GET_TIME field of RTC_CTRL_1 to store a timestamp in shadow registers. */
static int tps6594_rtc_shadow_timestamp(struct device *dev, struct tps6594 *tps)
{
int ret;
/*
* Set GET_TIME to 0. Next time we set GET_TIME to 1 we will be sure to store
* an up-to-date timestamp.
*/
ret = regmap_clear_bits(tps->regmap, TPS6594_REG_RTC_CTRL_1,
TPS6594_BIT_GET_TIME);
if (ret < 0)
return ret;
/*
* Copy content of RTC registers to shadow registers or latches to read
* a coherent timestamp.
*/
return regmap_set_bits(tps->regmap, TPS6594_REG_RTC_CTRL_1,
TPS6594_BIT_GET_TIME);
}
static int tps6594_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
unsigned char rtc_data[NUM_TIME_REGS];
struct tps6594 *tps = dev_get_drvdata(dev->parent);
int ret;
// Check if RTC is running.
ret = regmap_test_bits(tps->regmap, TPS6594_REG_RTC_STATUS,
TPS6594_BIT_RUN);
if (ret < 0)
return ret;
if (ret == 0)
return -EINVAL;
ret = tps6594_rtc_shadow_timestamp(dev, tps);
if (ret < 0)
return ret;
// Read shadowed RTC registers.
ret = regmap_bulk_read(tps->regmap, TPS6594_REG_RTC_SECONDS, rtc_data,
NUM_TIME_REGS);
if (ret < 0)
return ret;
tm->tm_sec = bcd2bin(rtc_data[0]);
tm->tm_min = bcd2bin(rtc_data[1]);
tm->tm_hour = bcd2bin(rtc_data[2]);
tm->tm_mday = bcd2bin(rtc_data[3]);
tm->tm_mon = bcd2bin(rtc_data[4]) - 1;
tm->tm_year = bcd2bin(rtc_data[5]) + 100;
tm->tm_wday = bcd2bin(rtc_data[6]);
return 0;
}
static int tps6594_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
unsigned char rtc_data[NUM_TIME_REGS];
struct tps6594 *tps = dev_get_drvdata(dev->parent);
int ret;
rtc_data[0] = bin2bcd(tm->tm_sec);
rtc_data[1] = bin2bcd(tm->tm_min);
rtc_data[2] = bin2bcd(tm->tm_hour);
rtc_data[3] = bin2bcd(tm->tm_mday);
rtc_data[4] = bin2bcd(tm->tm_mon + 1);
rtc_data[5] = bin2bcd(tm->tm_year - 100);
rtc_data[6] = bin2bcd(tm->tm_wday);
// Stop RTC while updating the RTC time registers.
ret = regmap_clear_bits(tps->regmap, TPS6594_REG_RTC_CTRL_1,
TPS6594_BIT_STOP_RTC);
if (ret < 0)
return ret;
// Update all the time registers in one shot.
ret = regmap_bulk_write(tps->regmap, TPS6594_REG_RTC_SECONDS, rtc_data,
NUM_TIME_REGS);
if (ret < 0)
return ret;
// Start back RTC.
return regmap_set_bits(tps->regmap, TPS6594_REG_RTC_CTRL_1,
TPS6594_BIT_STOP_RTC);
}
static int tps6594_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
unsigned char alarm_data[NUM_TIME_ALARM_REGS];
u32 int_val;
struct tps6594 *tps = dev_get_drvdata(dev->parent);
int ret;
ret = regmap_bulk_read(tps->regmap, TPS6594_REG_ALARM_SECONDS,
alarm_data, NUM_TIME_ALARM_REGS);
if (ret < 0)
return ret;
alm->time.tm_sec = bcd2bin(alarm_data[0]);
alm->time.tm_min = bcd2bin(alarm_data[1]);
alm->time.tm_hour = bcd2bin(alarm_data[2]);
alm->time.tm_mday = bcd2bin(alarm_data[3]);
alm->time.tm_mon = bcd2bin(alarm_data[4]) - 1;
alm->time.tm_year = bcd2bin(alarm_data[5]) + 100;
ret = regmap_read(tps->regmap, TPS6594_REG_RTC_INTERRUPTS, &int_val);
if (ret < 0)
return ret;
alm->enabled = int_val & TPS6594_BIT_IT_ALARM;
return 0;
}
static int tps6594_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
unsigned char alarm_data[NUM_TIME_ALARM_REGS];
struct tps6594 *tps = dev_get_drvdata(dev->parent);
int ret;
// Disable alarm irq before changing the alarm timestamp.
ret = tps6594_rtc_alarm_irq_enable(dev, 0);
if (ret)
return ret;
alarm_data[0] = bin2bcd(alm->time.tm_sec);
alarm_data[1] = bin2bcd(alm->time.tm_min);
alarm_data[2] = bin2bcd(alm->time.tm_hour);
alarm_data[3] = bin2bcd(alm->time.tm_mday);
alarm_data[4] = bin2bcd(alm->time.tm_mon + 1);
alarm_data[5] = bin2bcd(alm->time.tm_year - 100);
// Update all the alarm registers in one shot.
ret = regmap_bulk_write(tps->regmap, TPS6594_REG_ALARM_SECONDS,
alarm_data, NUM_TIME_ALARM_REGS);
if (ret < 0)
return ret;
if (alm->enabled)
ret = tps6594_rtc_alarm_irq_enable(dev, 1);
return ret;
}
static int tps6594_rtc_set_calibration(struct device *dev, int calibration)
{
struct tps6594 *tps = dev_get_drvdata(dev->parent);
__le16 value;
int ret;
/*
* TPS6594 uses two's complement 16 bit value for compensation of 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.
*
* Valid range for compensation value: [-32767 .. 32767].
*/
if (calibration < S16_MIN + 1 || calibration > S16_MAX)
return -ERANGE;
value = cpu_to_le16(calibration);
// Update all the compensation registers in one shot.
ret = regmap_bulk_write(tps->regmap, TPS6594_REG_RTC_COMP_LSB, &value,
sizeof(value));
if (ret < 0)
return ret;
// Enable automatic compensation.
return regmap_set_bits(tps->regmap, TPS6594_REG_RTC_CTRL_1,
TPS6594_BIT_AUTO_COMP);
}
static int tps6594_rtc_get_calibration(struct device *dev, int *calibration)
{
struct tps6594 *tps = dev_get_drvdata(dev->parent);
unsigned int ctrl;
__le16 value;
int ret;
ret = regmap_read(tps->regmap, TPS6594_REG_RTC_CTRL_1, &ctrl);
if (ret < 0)
return ret;
// If automatic compensation is not enabled report back zero.
if (!(ctrl & TPS6594_BIT_AUTO_COMP)) {
*calibration = 0;
return 0;
}
ret = regmap_bulk_read(tps->regmap, TPS6594_REG_RTC_COMP_LSB, &value,
sizeof(value));
if (ret < 0)
return ret;
*calibration = le16_to_cpu(value);
return 0;
}
static int tps6594_rtc_read_offset(struct device *dev, long *offset)
{
int calibration;
s64 tmp;
int ret;
ret = tps6594_rtc_get_calibration(dev, &calibration);
if (ret < 0)
return ret;
// Convert from RTC calibration register format to ppb format.
tmp = calibration * PPB_MULT;
if (tmp < 0)
tmp -= TICKS_PER_HOUR / 2LL;
else
tmp += TICKS_PER_HOUR / 2LL;
tmp = div_s64(tmp, TICKS_PER_HOUR);
/*
* SAFETY:
* Computatiion is the reverse operation of the one done in
* `tps6594_rtc_set_offset`. The safety remarks applie here too.
*/
/*
* Offset value operates in negative way, so swap sign.
* See 8.3.10.5, (32768 - COMP_REG).
*/
*offset = (long)-tmp;
return 0;
}
static int tps6594_rtc_set_offset(struct device *dev, long offset)
{
int calibration;
s64 tmp;
// 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 * TICKS_PER_HOUR;
if (tmp < 0)
tmp -= PPB_MULT / 2LL;
else
tmp += PPB_MULT / 2LL;
tmp = div_s64(tmp, PPB_MULT);
/*
* SAFETY:
* - tmp = offset * TICK_PER_HOUR :
* `offset` can't be more than 277774, so `tmp` can't exceed 277774000000000
* which is lower than the maximum value in an `s64` (2^63-1). No overflow here.
*
* - tmp += TICK_PER_HOUR / 2LL :
* tmp will have a maximum value of 277774117964800 which is still inferior to 2^63-1.
*/
// Offset value operates in negative way, so swap sign.
calibration = (int)-tmp;
return tps6594_rtc_set_calibration(dev, calibration);
}
static irqreturn_t tps6594_rtc_interrupt(int irq, void *rtc)
{
struct device *dev = rtc;
struct tps6594 *tps = dev_get_drvdata(dev->parent);
struct rtc_device *rtc_dev = dev_get_drvdata(dev);
int ret;
u32 rtc_reg;
ret = regmap_read(tps->regmap, TPS6594_REG_RTC_STATUS, &rtc_reg);
if (ret)
return IRQ_NONE;
rtc_update_irq(rtc_dev, 1, RTC_IRQF | RTC_AF);
return IRQ_HANDLED;
}
static const struct rtc_class_ops tps6594_rtc_ops = {
.read_time = tps6594_rtc_read_time,
.set_time = tps6594_rtc_set_time,
.read_alarm = tps6594_rtc_read_alarm,
.set_alarm = tps6594_rtc_set_alarm,
.alarm_irq_enable = tps6594_rtc_alarm_irq_enable,
.read_offset = tps6594_rtc_read_offset,
.set_offset = tps6594_rtc_set_offset,
};
static int tps6594_rtc_probe(struct platform_device *pdev)
{
struct tps6594 *tps = dev_get_drvdata(pdev->dev.parent);
struct device *dev = &pdev->dev;
struct rtc_device *rtc;
int irq;
int ret;
rtc = devm_kzalloc(dev, sizeof(*rtc), GFP_KERNEL);
if (!rtc)
return -ENOMEM;
rtc = devm_rtc_allocate_device(dev);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
// Enable crystal oscillator.
ret = regmap_set_bits(tps->regmap, TPS6594_REG_RTC_CTRL_2,
TPS6594_BIT_XTAL_EN);
if (ret < 0)
return ret;
ret = regmap_test_bits(tps->regmap, TPS6594_REG_RTC_STATUS,
TPS6594_BIT_RUN);
if (ret < 0)
return ret;
// RTC not running.
if (ret == 0) {
ret = regmap_set_bits(tps->regmap, TPS6594_REG_RTC_CTRL_1,
TPS6594_BIT_STOP_RTC);
if (ret < 0)
return ret;
/*
* On some boards, a 40 ms delay is needed before BIT_RUN is set.
* 80 ms should provide sufficient margin.
*/
mdelay(80);
/*
* RTC should be running now. Check if this is the case.
* If not it might be a missing oscillator.
*/
ret = regmap_test_bits(tps->regmap, TPS6594_REG_RTC_STATUS,
TPS6594_BIT_RUN);
if (ret < 0)
return ret;
if (ret == 0)
return -ENODEV;
// Stop RTC until first call to `tps6594_rtc_set_time`.
ret = regmap_clear_bits(tps->regmap, TPS6594_REG_RTC_CTRL_1,
TPS6594_BIT_STOP_RTC);
if (ret < 0)
return ret;
}
platform_set_drvdata(pdev, rtc);
irq = platform_get_irq_byname(pdev, TPS6594_IRQ_NAME_ALARM);
if (irq < 0)
return dev_err_probe(dev, irq, "Failed to get irq\n");
ret = devm_request_threaded_irq(dev, irq, NULL, tps6594_rtc_interrupt,
IRQF_ONESHOT, TPS6594_IRQ_NAME_ALARM,
dev);
if (ret < 0)
return dev_err_probe(dev, ret,
"Failed to request_threaded_irq\n");
ret = device_init_wakeup(dev, true);
if (ret < 0)
return dev_err_probe(dev, ret,
"Failed to init rtc as wakeup source\n");
rtc->ops = &tps6594_rtc_ops;
rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
rtc->range_max = RTC_TIMESTAMP_END_2099;
return devm_rtc_register_device(rtc);
}
static const struct platform_device_id tps6594_rtc_id_table[] = {
{ "tps6594-rtc", },
{}
};
MODULE_DEVICE_TABLE(platform, tps6594_rtc_id_table);
static struct platform_driver tps6594_rtc_driver = {
.probe = tps6594_rtc_probe,
.driver = {
.name = "tps6594-rtc",
},
.id_table = tps6594_rtc_id_table,
};
module_platform_driver(tps6594_rtc_driver);
MODULE_AUTHOR("Esteban Blanc <eblanc@baylibre.com>");
MODULE_DESCRIPTION("TPS6594 RTC driver");
MODULE_LICENSE("GPL");
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