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linux/drivers/rtc/rtc-tps6594.c
Richard Genoud c88014c7aa rtc: tps6594: Add power management support 
Add power management support to the driver. This allows a SoC to wake
from suspend using the nINT provided by the RTC.
It takes care of the case when the interrupt has not been caught because
the kernel has not yet woke up.
(This is the case when only edges interrupt are caught)

Signed-off-by: Richard Genoud <richard.genoud@bootlin.com>
Link: https://lore.kernel.org/r/20240618141851.1810000-4-richard.genoud@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2024-06-28 00:18:55 +02:00

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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
struct tps6594_rtc {
struct rtc_device *rtc_dev;
int irq;
};
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 *data)
{
struct device *dev = data;
struct tps6594 *tps = dev_get_drvdata(dev->parent);
struct tps6594_rtc *rtc = 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->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 tps6594_rtc *rtc;
int irq;
int ret;
rtc = devm_kzalloc(dev, sizeof(*rtc), GFP_KERNEL);
if (!rtc)
return -ENOMEM;
rtc->rtc_dev = devm_rtc_allocate_device(dev);
if (IS_ERR(rtc->rtc_dev))
return PTR_ERR(rtc->rtc_dev);
// 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");
rtc->irq = irq;
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->rtc_dev->ops = &tps6594_rtc_ops;
rtc->rtc_dev->range_min = RTC_TIMESTAMP_BEGIN_2000;
rtc->rtc_dev->range_max = RTC_TIMESTAMP_END_2099;
return devm_rtc_register_device(rtc->rtc_dev);
}
static int tps6594_rtc_resume(struct device *dev)
{
struct tps6594 *tps = dev_get_drvdata(dev->parent);
struct tps6594_rtc *rtc = dev_get_drvdata(dev);
int ret;
ret = regmap_test_bits(tps->regmap, TPS6594_REG_INT_STARTUP,
TPS6594_BIT_RTC_INT);
if (ret < 0) {
dev_err(dev, "failed to read REG_INT_STARTUP: %d\n", ret);
goto out;
}
if (ret > 0) {
/*
* If the alarm bit is set, it means that the IRQ has been
* fired. But, the kernel may not have woke up yet when it
* happened. So, we have to clear it.
*/
ret = regmap_write(tps->regmap, TPS6594_REG_RTC_STATUS,
TPS6594_BIT_ALARM);
if (ret < 0)
dev_err(dev, "error clearing alarm bit: %d", ret);
rtc_update_irq(rtc->rtc_dev, 1, RTC_IRQF | RTC_AF);
}
out:
disable_irq_wake(rtc->irq);
return 0;
}
static int tps6594_rtc_suspend(struct device *dev)
{
struct tps6594_rtc *rtc = dev_get_drvdata(dev);
enable_irq_wake(rtc->irq);
return 0;
}
static DEFINE_SIMPLE_DEV_PM_OPS(tps6594_rtc_pm_ops, tps6594_rtc_suspend, tps6594_rtc_resume);
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",
.pm = pm_sleep_ptr(&tps6594_rtc_pm_ops),
},
.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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