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From:   andy.shevchenko@gmail.com
Date:   Wed, 5 Jul 2023 12:45:23 +0300
To:     Esteban Blanc <eblanc@baylibre.com>
Cc:     linus.walleij@linaro.org, a.zummo@towertech.it,
        alexandre.belloni@bootlin.com, linux-kernel@vger.kernel.org,
        linux-gpio@vger.kernel.org, linux-rtc@vger.kernel.org,
        jpanis@baylibre.com, jneanne@baylibre.com, aseketeli@baylibre.com,
        u-kumar1@ti.com
Subject: Re: [PATCH v7 1/2] rtc: tps6594: Add driver for TPS6594 RTC
Message-ID: <ZKU7s-q0Q_ZWWVgd@surfacebook>
References: <20230628133021.500477-1-eblanc@baylibre.com>
 <20230628133021.500477-2-eblanc@baylibre.com>
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In-Reply-To: <20230628133021.500477-2-eblanc@baylibre.com>
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Wed, Jun 28, 2023 at 03:30:20PM +0200, Esteban Blanc kirjoitti:
> TPS6594 PMIC is a MFD. This patch adds support for
> the RTC found inside TPS6594 family of PMIC.
> 
> Alarm is also supported.

LGTM from generic style and code comments perspective,
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> Signed-off-by: Esteban Blanc <eblanc@baylibre.com>
> ---
>  drivers/rtc/Kconfig       |  12 +
>  drivers/rtc/Makefile      |   1 +
>  drivers/rtc/rtc-tps6594.c | 452 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 465 insertions(+)
>  create mode 100644 drivers/rtc/rtc-tps6594.c
> 
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 753872408615..39b5c93c6282 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -578,6 +578,18 @@ config RTC_DRV_TPS6586X
>  	  along with alarm. This driver supports the RTC driver for
>  	  the TPS6586X RTC module.
>  
> +config RTC_DRV_TPS6594
> +	tristate "TI TPS6594 RTC driver"
> +	depends on MFD_TPS6594
> +	default MFD_TPS6594
> +	help
> +	  TI Power Management IC TPS6594 supports RTC functionality
> +	  along with alarm. This driver supports the RTC driver for
> +	  the TPS6594 RTC module.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called rtc-tps6594.
> +
>  config RTC_DRV_TPS65910
>  	tristate "TI TPS65910 RTC driver"
>  	depends on MFD_TPS65910
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index ea445d1ebb17..3d3f8c9d0697 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -175,6 +175,7 @@ obj-$(CONFIG_RTC_DRV_TEGRA)	+= rtc-tegra.o
>  obj-$(CONFIG_RTC_DRV_TEST)	+= rtc-test.o
>  obj-$(CONFIG_RTC_DRV_TI_K3)	+= rtc-ti-k3.o
>  obj-$(CONFIG_RTC_DRV_TPS6586X)	+= rtc-tps6586x.o
> +obj-$(CONFIG_RTC_DRV_TPS6594)	+= rtc-tps6594.o
>  obj-$(CONFIG_RTC_DRV_TPS65910)	+= rtc-tps65910.o
>  obj-$(CONFIG_RTC_DRV_TWL4030)	+= rtc-twl.o
>  obj-$(CONFIG_RTC_DRV_VT8500)	+= rtc-vt8500.o
> diff --git a/drivers/rtc/rtc-tps6594.c b/drivers/rtc/rtc-tps6594.c
> new file mode 100644
> index 000000000000..7328ea7da849
> --- /dev/null
> +++ b/drivers/rtc/rtc-tps6594.c
> @@ -0,0 +1,452 @@
> +// 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/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:
> +	 * Compution 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;
> +	unsigned long events = 0;
> +	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;
> +
> +	if (rtc_reg & TPS6594_BIT_ALARM)
> +		events = RTC_IRQF | RTC_AF;
> +
> +	// Notify RTC core on event.
> +	rtc_update_irq(rtc_dev, 1, events);
> +
> +	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 struct platform_driver tps6594_rtc_driver = {
> +	.probe		= tps6594_rtc_probe,
> +	.driver		= {
> +		.name	= "tps6594-rtc",
> +	},
> +};
> +
> +module_platform_driver(tps6594_rtc_driver);
> +MODULE_ALIAS("platform:tps6594-rtc");
> +MODULE_AUTHOR("Esteban Blanc <eblanc@baylibre.com>");
> +MODULE_DESCRIPTION("TPS6594 RTC driver");
> +MODULE_LICENSE("GPL");
> -- 
> 2.41.0
> 

-- 
With Best Regards,
Andy Shevchenko