root/drivers/rtc/rtc-tps6586x.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * rtc-tps6586x.c: RTC driver for TI PMIC TPS6586X
 *
 * Copyright (c) 2012, NVIDIA Corporation.
 *
 * Author: Laxman Dewangan <ldewangan@nvidia.com>
 */

#include <linux/device.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/mfd/tps6586x.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/rtc.h>
#include <linux/slab.h>

#define RTC_CTRL                        0xc0
#define POR_RESET_N                     BIT(7)
#define OSC_SRC_SEL                     BIT(6)
#define RTC_ENABLE                      BIT(5)  /* enables alarm */
#define RTC_BUF_ENABLE                  BIT(4)  /* 32 KHz buffer enable */
#define PRE_BYPASS                      BIT(3)  /* 0=1KHz or 1=32KHz updates */
#define CL_SEL_MASK                     (BIT(2)|BIT(1))
#define CL_SEL_POS                      1
#define RTC_ALARM1_HI                   0xc1
#define RTC_COUNT4                      0xc6

/* start a PMU RTC access by reading the register prior to the RTC_COUNT4 */
#define RTC_COUNT4_DUMMYREAD            0xc5

/*only 14-bits width in second*/
#define ALM1_VALID_RANGE_IN_SEC         0x3FFF

#define TPS6586X_RTC_CL_SEL_1_5PF       0x0
#define TPS6586X_RTC_CL_SEL_6_5PF       0x1
#define TPS6586X_RTC_CL_SEL_7_5PF       0x2
#define TPS6586X_RTC_CL_SEL_12_5PF      0x3

struct tps6586x_rtc {
        struct device           *dev;
        struct rtc_device       *rtc;
        int                     irq;
        bool                    irq_en;
};

static inline struct device *to_tps6586x_dev(struct device *dev)
{
        return dev->parent;
}

static int tps6586x_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct device *tps_dev = to_tps6586x_dev(dev);
        unsigned long long ticks = 0;
        time64_t seconds;
        u8 buff[6];
        int ret;
        int i;

        ret = tps6586x_reads(tps_dev, RTC_COUNT4_DUMMYREAD, sizeof(buff), buff);
        if (ret < 0) {
                dev_err(dev, "read counter failed with err %d\n", ret);
                return ret;
        }

        for (i = 1; i < sizeof(buff); i++) {
                ticks <<= 8;
                ticks |= buff[i];
        }

        seconds = ticks >> 10;
        rtc_time64_to_tm(seconds, tm);

        return 0;
}

static int tps6586x_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct device *tps_dev = to_tps6586x_dev(dev);
        unsigned long long ticks;
        time64_t seconds;
        u8 buff[5];
        int ret;

        seconds = rtc_tm_to_time64(tm);

        ticks = (unsigned long long)seconds << 10;
        buff[0] = (ticks >> 32) & 0xff;
        buff[1] = (ticks >> 24) & 0xff;
        buff[2] = (ticks >> 16) & 0xff;
        buff[3] = (ticks >> 8) & 0xff;
        buff[4] = ticks & 0xff;

        /* Disable RTC before changing time */
        ret = tps6586x_clr_bits(tps_dev, RTC_CTRL, RTC_ENABLE);
        if (ret < 0) {
                dev_err(dev, "failed to clear RTC_ENABLE\n");
                return ret;
        }

        ret = tps6586x_writes(tps_dev, RTC_COUNT4, sizeof(buff), buff);
        if (ret < 0) {
                dev_err(dev, "failed to program new time\n");
                return ret;
        }

        /* Enable RTC */
        ret = tps6586x_set_bits(tps_dev, RTC_CTRL, RTC_ENABLE);
        if (ret < 0) {
                dev_err(dev, "failed to set RTC_ENABLE\n");
                return ret;
        }
        return 0;
}

static int tps6586x_rtc_alarm_irq_enable(struct device *dev,
                         unsigned int enabled)
{
        struct tps6586x_rtc *rtc = dev_get_drvdata(dev);

        if (enabled && !rtc->irq_en) {
                enable_irq(rtc->irq);
                rtc->irq_en = true;
        } else if (!enabled && rtc->irq_en)  {
                disable_irq(rtc->irq);
                rtc->irq_en = false;
        }
        return 0;
}

static int tps6586x_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct device *tps_dev = to_tps6586x_dev(dev);
        time64_t seconds;
        unsigned long ticks;
        unsigned long rtc_current_time;
        unsigned long long rticks = 0;
        u8 buff[3];
        u8 rbuff[6];
        int ret;
        int i;

        seconds = rtc_tm_to_time64(&alrm->time);

        ret = tps6586x_rtc_alarm_irq_enable(dev, alrm->enabled);
        if (ret < 0) {
                dev_err(dev, "can't set alarm irq, err %d\n", ret);
                return ret;
        }

        ret = tps6586x_reads(tps_dev, RTC_COUNT4_DUMMYREAD,
                        sizeof(rbuff), rbuff);
        if (ret < 0) {
                dev_err(dev, "read counter failed with err %d\n", ret);
                return ret;
        }

        for (i = 1; i < sizeof(rbuff); i++) {
                rticks <<= 8;
                rticks |= rbuff[i];
        }

        rtc_current_time = rticks >> 10;
        if ((seconds - rtc_current_time) > ALM1_VALID_RANGE_IN_SEC)
                seconds = rtc_current_time - 1;

        ticks = (unsigned long long)seconds << 10;
        buff[0] = (ticks >> 16) & 0xff;
        buff[1] = (ticks >> 8) & 0xff;
        buff[2] = ticks & 0xff;

        ret = tps6586x_writes(tps_dev, RTC_ALARM1_HI, sizeof(buff), buff);
        if (ret)
                dev_err(dev, "programming alarm failed with err %d\n", ret);

        return ret;
}

static int tps6586x_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct device *tps_dev = to_tps6586x_dev(dev);
        unsigned long ticks;
        time64_t seconds;
        u8 buff[3];
        int ret;

        ret = tps6586x_reads(tps_dev, RTC_ALARM1_HI, sizeof(buff), buff);
        if (ret) {
                dev_err(dev, "read RTC_ALARM1_HI failed with err %d\n", ret);
                return ret;
        }

        ticks = (buff[0] << 16) | (buff[1] << 8) | buff[2];
        seconds = ticks >> 10;

        rtc_time64_to_tm(seconds, &alrm->time);
        return 0;
}

static const struct rtc_class_ops tps6586x_rtc_ops = {
        .read_time      = tps6586x_rtc_read_time,
        .set_time       = tps6586x_rtc_set_time,
        .set_alarm      = tps6586x_rtc_set_alarm,
        .read_alarm     = tps6586x_rtc_read_alarm,
        .alarm_irq_enable = tps6586x_rtc_alarm_irq_enable,
};

static irqreturn_t tps6586x_rtc_irq(int irq, void *data)
{
        struct tps6586x_rtc *rtc = data;

        rtc_update_irq(rtc->rtc, 1, RTC_IRQF | RTC_AF);
        return IRQ_HANDLED;
}

static int tps6586x_rtc_probe(struct platform_device *pdev)
{
        struct device *tps_dev = to_tps6586x_dev(&pdev->dev);
        struct tps6586x_rtc *rtc;
        int ret;

        rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
        if (!rtc)
                return -ENOMEM;

        rtc->dev = &pdev->dev;
        rtc->irq = platform_get_irq(pdev, 0);

        /* 1 kHz tick mode, enable tick counting */
        ret = tps6586x_update(tps_dev, RTC_CTRL,
                RTC_ENABLE | OSC_SRC_SEL |
                ((TPS6586X_RTC_CL_SEL_1_5PF << CL_SEL_POS) & CL_SEL_MASK),
                RTC_ENABLE | OSC_SRC_SEL | PRE_BYPASS | CL_SEL_MASK);
        if (ret < 0) {
                dev_err(&pdev->dev, "unable to start counter\n");
                return ret;
        }

        device_init_wakeup(&pdev->dev, true);

        platform_set_drvdata(pdev, rtc);
        rtc->rtc = devm_rtc_allocate_device(&pdev->dev);
        if (IS_ERR(rtc->rtc)) {
                ret = PTR_ERR(rtc->rtc);
                goto fail_rtc_register;
        }

        rtc->rtc->ops = &tps6586x_rtc_ops;
        rtc->rtc->range_max = (1ULL << 30) - 1; /* 30-bit seconds */
        rtc->rtc->alarm_offset_max = ALM1_VALID_RANGE_IN_SEC;
        rtc->rtc->start_secs = mktime64(2009, 1, 1, 0, 0, 0);
        rtc->rtc->set_start_time = true;

        irq_set_status_flags(rtc->irq, IRQ_NOAUTOEN);

        ret = devm_request_threaded_irq(&pdev->dev, rtc->irq, NULL,
                                tps6586x_rtc_irq,
                                IRQF_ONESHOT,
                                dev_name(&pdev->dev), rtc);
        if (ret < 0) {
                dev_err(&pdev->dev, "request IRQ(%d) failed with ret %d\n",
                                rtc->irq, ret);
                goto fail_rtc_register;
        }

        ret = devm_rtc_register_device(rtc->rtc);
        if (ret)
                goto fail_rtc_register;

        return 0;

fail_rtc_register:
        tps6586x_update(tps_dev, RTC_CTRL, 0,
                RTC_ENABLE | OSC_SRC_SEL | PRE_BYPASS | CL_SEL_MASK);
        return ret;
};

static void tps6586x_rtc_remove(struct platform_device *pdev)
{
        struct device *tps_dev = to_tps6586x_dev(&pdev->dev);

        tps6586x_update(tps_dev, RTC_CTRL, 0,
                RTC_ENABLE | OSC_SRC_SEL | PRE_BYPASS | CL_SEL_MASK);
}

#ifdef CONFIG_PM_SLEEP
static int tps6586x_rtc_suspend(struct device *dev)
{
        struct tps6586x_rtc *rtc = dev_get_drvdata(dev);

        if (device_may_wakeup(dev))
                enable_irq_wake(rtc->irq);
        return 0;
}

static int tps6586x_rtc_resume(struct device *dev)
{
        struct tps6586x_rtc *rtc = dev_get_drvdata(dev);

        if (device_may_wakeup(dev))
                disable_irq_wake(rtc->irq);
        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(tps6586x_pm_ops, tps6586x_rtc_suspend,
                        tps6586x_rtc_resume);

static struct platform_driver tps6586x_rtc_driver = {
        .driver = {
                .name   = "tps6586x-rtc",
                .pm     = &tps6586x_pm_ops,
        },
        .probe  = tps6586x_rtc_probe,
        .remove = tps6586x_rtc_remove,
};
module_platform_driver(tps6586x_rtc_driver);

MODULE_ALIAS("platform:tps6586x-rtc");
MODULE_DESCRIPTION("TI TPS6586x RTC driver");
MODULE_AUTHOR("Laxman dewangan <ldewangan@nvidia.com>");
MODULE_LICENSE("GPL v2");