root/drivers/rtc/rtc-palmas.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * rtc-palmas.c -- Palmas Real Time Clock driver.

 * RTC driver for TI Palma series devices like TPS65913,
 * TPS65914 power management IC.
 *
 * Copyright (c) 2012, NVIDIA Corporation.
 *
 * Author: Laxman Dewangan <ldewangan@nvidia.com>
 */

#include <linux/bcd.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/mfd/palmas.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/rtc.h>
#include <linux/types.h>
#include <linux/platform_device.h>
#include <linux/pm.h>

struct palmas_rtc {
        struct rtc_device       *rtc;
        struct device           *dev;
        unsigned int            irq;
};

/* Total number of RTC registers needed to set time*/
#define PALMAS_NUM_TIME_REGS    (PALMAS_YEARS_REG - PALMAS_SECONDS_REG + 1)

static int palmas_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        unsigned char rtc_data[PALMAS_NUM_TIME_REGS];
        struct palmas *palmas = dev_get_drvdata(dev->parent);
        int ret;

        /* Copy RTC counting registers to static registers or latches */
        ret = palmas_update_bits(palmas, PALMAS_RTC_BASE, PALMAS_RTC_CTRL_REG,
                PALMAS_RTC_CTRL_REG_GET_TIME, PALMAS_RTC_CTRL_REG_GET_TIME);
        if (ret < 0) {
                dev_err(dev, "RTC CTRL reg update failed, err: %d\n", ret);
                return ret;
        }

        ret = palmas_bulk_read(palmas, PALMAS_RTC_BASE, PALMAS_SECONDS_REG,
                        rtc_data, PALMAS_NUM_TIME_REGS);
        if (ret < 0) {
                dev_err(dev, "RTC_SECONDS reg read failed, err = %d\n", ret);
                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;

        return ret;
}

static int palmas_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        unsigned char rtc_data[PALMAS_NUM_TIME_REGS];
        struct palmas *palmas = 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);

        /* Stop RTC while updating the RTC time registers */
        ret = palmas_update_bits(palmas, PALMAS_RTC_BASE, PALMAS_RTC_CTRL_REG,
                PALMAS_RTC_CTRL_REG_STOP_RTC, 0);
        if (ret < 0) {
                dev_err(dev, "RTC stop failed, err = %d\n", ret);
                return ret;
        }

        ret = palmas_bulk_write(palmas, PALMAS_RTC_BASE, PALMAS_SECONDS_REG,
                rtc_data, PALMAS_NUM_TIME_REGS);
        if (ret < 0) {
                dev_err(dev, "RTC_SECONDS reg write failed, err = %d\n", ret);
                return ret;
        }

        /* Start back RTC */
        ret = palmas_update_bits(palmas, PALMAS_RTC_BASE, PALMAS_RTC_CTRL_REG,
                PALMAS_RTC_CTRL_REG_STOP_RTC, PALMAS_RTC_CTRL_REG_STOP_RTC);
        if (ret < 0)
                dev_err(dev, "RTC start failed, err = %d\n", ret);
        return ret;
}

static int palmas_rtc_alarm_irq_enable(struct device *dev, unsigned enabled)
{
        struct palmas *palmas = dev_get_drvdata(dev->parent);
        u8 val;

        val = enabled ? PALMAS_RTC_INTERRUPTS_REG_IT_ALARM : 0;
        return palmas_write(palmas, PALMAS_RTC_BASE,
                PALMAS_RTC_INTERRUPTS_REG, val);
}

static int palmas_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
        unsigned char alarm_data[PALMAS_NUM_TIME_REGS];
        u32 int_val;
        struct palmas *palmas = dev_get_drvdata(dev->parent);
        int ret;

        ret = palmas_bulk_read(palmas, PALMAS_RTC_BASE,
                        PALMAS_ALARM_SECONDS_REG,
                        alarm_data, PALMAS_NUM_TIME_REGS);
        if (ret < 0) {
                dev_err(dev, "RTC_ALARM_SECONDS read failed, err = %d\n", ret);
                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 = palmas_read(palmas, PALMAS_RTC_BASE, PALMAS_RTC_INTERRUPTS_REG,
                        &int_val);
        if (ret < 0) {
                dev_err(dev, "RTC_INTERRUPTS reg read failed, err = %d\n", ret);
                return ret;
        }

        if (int_val & PALMAS_RTC_INTERRUPTS_REG_IT_ALARM)
                alm->enabled = 1;
        return ret;
}

static int palmas_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
        unsigned char alarm_data[PALMAS_NUM_TIME_REGS];
        struct palmas *palmas = dev_get_drvdata(dev->parent);
        int ret;

        ret = palmas_rtc_alarm_irq_enable(dev, 0);
        if (ret < 0) {
                dev_err(dev, "Disable RTC alarm failed\n");
                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);

        ret = palmas_bulk_write(palmas, PALMAS_RTC_BASE,
                PALMAS_ALARM_SECONDS_REG, alarm_data, PALMAS_NUM_TIME_REGS);
        if (ret < 0) {
                dev_err(dev, "ALARM_SECONDS_REG write failed, err = %d\n", ret);
                return ret;
        }

        if (alm->enabled)
                ret = palmas_rtc_alarm_irq_enable(dev, 1);
        return ret;
}

static int palmas_clear_interrupts(struct device *dev)
{
        struct palmas *palmas = dev_get_drvdata(dev->parent);
        unsigned int rtc_reg;
        int ret;

        ret = palmas_read(palmas, PALMAS_RTC_BASE, PALMAS_RTC_STATUS_REG,
                                &rtc_reg);
        if (ret < 0) {
                dev_err(dev, "RTC_STATUS read failed, err = %d\n", ret);
                return ret;
        }

        ret = palmas_write(palmas, PALMAS_RTC_BASE, PALMAS_RTC_STATUS_REG,
                        rtc_reg);
        if (ret < 0) {
                dev_err(dev, "RTC_STATUS write failed, err = %d\n", ret);
                return ret;
        }
        return 0;
}

static irqreturn_t palmas_rtc_interrupt(int irq, void *context)
{
        struct palmas_rtc *palmas_rtc = context;
        struct device *dev = palmas_rtc->dev;
        int ret;

        ret = palmas_clear_interrupts(dev);
        if (ret < 0) {
                dev_err(dev, "RTC interrupt clear failed, err = %d\n", ret);
                return IRQ_NONE;
        }

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

static const struct rtc_class_ops palmas_rtc_ops = {
        .read_time      = palmas_rtc_read_time,
        .set_time       = palmas_rtc_set_time,
        .read_alarm     = palmas_rtc_read_alarm,
        .set_alarm      = palmas_rtc_set_alarm,
        .alarm_irq_enable = palmas_rtc_alarm_irq_enable,
};

static int palmas_rtc_probe(struct platform_device *pdev)
{
        struct palmas *palmas = dev_get_drvdata(pdev->dev.parent);
        struct palmas_rtc *palmas_rtc = NULL;
        int ret;
        bool enable_bb_charging = false;
        bool high_bb_charging = false;

        if (pdev->dev.of_node) {
                enable_bb_charging = of_property_read_bool(pdev->dev.of_node,
                                        "ti,backup-battery-chargeable");
                high_bb_charging = of_property_read_bool(pdev->dev.of_node,
                                        "ti,backup-battery-charge-high-current");
        }

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

        /* Clear pending interrupts */
        ret = palmas_clear_interrupts(&pdev->dev);
        if (ret < 0) {
                dev_err(&pdev->dev, "clear RTC int failed, err = %d\n", ret);
                return ret;
        }

        palmas_rtc->dev = &pdev->dev;
        platform_set_drvdata(pdev, palmas_rtc);

        if (enable_bb_charging) {
                unsigned reg = PALMAS_BACKUP_BATTERY_CTRL_BBS_BBC_LOW_ICHRG;

                if (high_bb_charging)
                        reg = 0;

                ret = palmas_update_bits(palmas, PALMAS_PMU_CONTROL_BASE,
                        PALMAS_BACKUP_BATTERY_CTRL,
                        PALMAS_BACKUP_BATTERY_CTRL_BBS_BBC_LOW_ICHRG, reg);
                if (ret < 0) {
                        dev_err(&pdev->dev,
                                "BACKUP_BATTERY_CTRL update failed, %d\n", ret);
                        return ret;
                }

                ret = palmas_update_bits(palmas, PALMAS_PMU_CONTROL_BASE,
                        PALMAS_BACKUP_BATTERY_CTRL,
                        PALMAS_BACKUP_BATTERY_CTRL_BB_CHG_EN,
                        PALMAS_BACKUP_BATTERY_CTRL_BB_CHG_EN);
                if (ret < 0) {
                        dev_err(&pdev->dev,
                                "BACKUP_BATTERY_CTRL update failed, %d\n", ret);
                        return ret;
                }
        }

        /* Start RTC */
        ret = palmas_update_bits(palmas, PALMAS_RTC_BASE, PALMAS_RTC_CTRL_REG,
                        PALMAS_RTC_CTRL_REG_STOP_RTC,
                        PALMAS_RTC_CTRL_REG_STOP_RTC);
        if (ret < 0) {
                dev_err(&pdev->dev, "RTC_CTRL write failed, err = %d\n", ret);
                return ret;
        }

        palmas_rtc->irq = platform_get_irq(pdev, 0);

        device_init_wakeup(&pdev->dev, true);
        palmas_rtc->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
                                &palmas_rtc_ops, THIS_MODULE);
        if (IS_ERR(palmas_rtc->rtc)) {
                ret = PTR_ERR(palmas_rtc->rtc);
                dev_err(&pdev->dev, "RTC register failed, err = %d\n", ret);
                return ret;
        }

        ret = devm_request_threaded_irq(&pdev->dev, palmas_rtc->irq, NULL,
                        palmas_rtc_interrupt,
                        IRQF_TRIGGER_LOW | IRQF_ONESHOT,
                        dev_name(&pdev->dev), palmas_rtc);
        if (ret < 0) {
                dev_err(&pdev->dev, "IRQ request failed, err = %d\n", ret);
                return ret;
        }

        return 0;
}

static void palmas_rtc_remove(struct platform_device *pdev)
{
        palmas_rtc_alarm_irq_enable(&pdev->dev, 0);
}

#ifdef CONFIG_PM_SLEEP
static int palmas_rtc_suspend(struct device *dev)
{
        struct palmas_rtc *palmas_rtc = dev_get_drvdata(dev);

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

static int palmas_rtc_resume(struct device *dev)
{
        struct palmas_rtc *palmas_rtc = dev_get_drvdata(dev);

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

static SIMPLE_DEV_PM_OPS(palmas_rtc_pm_ops, palmas_rtc_suspend,
                         palmas_rtc_resume);

#ifdef CONFIG_OF
static const struct of_device_id of_palmas_rtc_match[] = {
        { .compatible = "ti,palmas-rtc"},
        { },
};
MODULE_DEVICE_TABLE(of, of_palmas_rtc_match);
#endif

static struct platform_driver palmas_rtc_driver = {
        .probe          = palmas_rtc_probe,
        .remove         = palmas_rtc_remove,
        .driver         = {
                .name   = "palmas-rtc",
                .pm     = &palmas_rtc_pm_ops,
                .of_match_table = of_match_ptr(of_palmas_rtc_match),
        },
};

module_platform_driver(palmas_rtc_driver);

MODULE_ALIAS("platform:palmas_rtc");
MODULE_DESCRIPTION("TI PALMAS series RTC driver");
MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
MODULE_LICENSE("GPL v2");