drivers/rtc/rtc-twl.c - kernel/msm-4.9 - Gitiles

 /*
  * rtc-twl.c -- TWL Real Time Clock interface
  *
  * Copyright (C) 2007 MontaVista Software, Inc
  * Author: Alexandre Rusev <source@mvista.com>
  *
  * Based on original TI driver twl4030-rtc.c
  *   Copyright (C) 2006 Texas Instruments, Inc.
  *
  * Based on rtc-omap.c
  *   Copyright (C) 2003 MontaVista Software, Inc.
  *   Author: George G. Davis <gdavis@mvista.com> or <source@mvista.com>
  *   Copyright (C) 2006 David Brownell
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version
  * 2 of the License, or (at your option) any later version.
  */

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

 #include <linux/i2c/twl.h>


 /*
  * RTC block register offsets (use TWL_MODULE_RTC)
  */
 enum {
 	REG_SECONDS_REG = 0,
 	REG_MINUTES_REG,
 	REG_HOURS_REG,
 	REG_DAYS_REG,
 	REG_MONTHS_REG,
 	REG_YEARS_REG,
 	REG_WEEKS_REG,

 	REG_ALARM_SECONDS_REG,
 	REG_ALARM_MINUTES_REG,
 	REG_ALARM_HOURS_REG,
 	REG_ALARM_DAYS_REG,
 	REG_ALARM_MONTHS_REG,
 	REG_ALARM_YEARS_REG,

 	REG_RTC_CTRL_REG,
 	REG_RTC_STATUS_REG,
 	REG_RTC_INTERRUPTS_REG,

 	REG_RTC_COMP_LSB_REG,
 	REG_RTC_COMP_MSB_REG,
 };
 static const u8 twl4030_rtc_reg_map[] = {
 	[REG_SECONDS_REG] = 0x00,
 	[REG_MINUTES_REG] = 0x01,
 	[REG_HOURS_REG] = 0x02,
 	[REG_DAYS_REG] = 0x03,
 	[REG_MONTHS_REG] = 0x04,
 	[REG_YEARS_REG] = 0x05,
 	[REG_WEEKS_REG] = 0x06,

 	[REG_ALARM_SECONDS_REG] = 0x07,
 	[REG_ALARM_MINUTES_REG] = 0x08,
 	[REG_ALARM_HOURS_REG] = 0x09,
 	[REG_ALARM_DAYS_REG] = 0x0A,
 	[REG_ALARM_MONTHS_REG] = 0x0B,
 	[REG_ALARM_YEARS_REG] = 0x0C,

 	[REG_RTC_CTRL_REG] = 0x0D,
 	[REG_RTC_STATUS_REG] = 0x0E,
 	[REG_RTC_INTERRUPTS_REG] = 0x0F,

 	[REG_RTC_COMP_LSB_REG] = 0x10,
 	[REG_RTC_COMP_MSB_REG] = 0x11,
 };
 static const u8 twl6030_rtc_reg_map[] = {
 	[REG_SECONDS_REG] = 0x00,
 	[REG_MINUTES_REG] = 0x01,
 	[REG_HOURS_REG] = 0x02,
 	[REG_DAYS_REG] = 0x03,
 	[REG_MONTHS_REG] = 0x04,
 	[REG_YEARS_REG] = 0x05,
 	[REG_WEEKS_REG] = 0x06,

 	[REG_ALARM_SECONDS_REG] = 0x08,
 	[REG_ALARM_MINUTES_REG] = 0x09,
 	[REG_ALARM_HOURS_REG] = 0x0A,
 	[REG_ALARM_DAYS_REG] = 0x0B,
 	[REG_ALARM_MONTHS_REG] = 0x0C,
 	[REG_ALARM_YEARS_REG] = 0x0D,

 	[REG_RTC_CTRL_REG] = 0x10,
 	[REG_RTC_STATUS_REG] = 0x11,
 	[REG_RTC_INTERRUPTS_REG] = 0x12,

 	[REG_RTC_COMP_LSB_REG] = 0x13,
 	[REG_RTC_COMP_MSB_REG] = 0x14,
 };

 /* RTC_CTRL_REG bitfields */
 #define BIT_RTC_CTRL_REG_STOP_RTC_M              0x01
 #define BIT_RTC_CTRL_REG_ROUND_30S_M             0x02
 #define BIT_RTC_CTRL_REG_AUTO_COMP_M             0x04
 #define BIT_RTC_CTRL_REG_MODE_12_24_M            0x08
 #define BIT_RTC_CTRL_REG_TEST_MODE_M             0x10
 #define BIT_RTC_CTRL_REG_SET_32_COUNTER_M        0x20
 #define BIT_RTC_CTRL_REG_GET_TIME_M              0x40
 #define BIT_RTC_CTRL_REG_RTC_V_OPT               0x80

 /* RTC_STATUS_REG bitfields */
 #define BIT_RTC_STATUS_REG_RUN_M                 0x02
 #define BIT_RTC_STATUS_REG_1S_EVENT_M            0x04
 #define BIT_RTC_STATUS_REG_1M_EVENT_M            0x08
 #define BIT_RTC_STATUS_REG_1H_EVENT_M            0x10
 #define BIT_RTC_STATUS_REG_1D_EVENT_M            0x20
 #define BIT_RTC_STATUS_REG_ALARM_M               0x40
 #define BIT_RTC_STATUS_REG_POWER_UP_M            0x80

 /* RTC_INTERRUPTS_REG bitfields */
 #define BIT_RTC_INTERRUPTS_REG_EVERY_M           0x03
 #define BIT_RTC_INTERRUPTS_REG_IT_TIMER_M        0x04
 #define BIT_RTC_INTERRUPTS_REG_IT_ALARM_M        0x08


 /* REG_SECONDS_REG through REG_YEARS_REG is how many registers? */
 #define ALL_TIME_REGS		6

 /*----------------------------------------------------------------------*/
 static u8  *rtc_reg_map;

 /*
  * Supports 1 byte read from TWL RTC register.
  */
 static int twl_rtc_read_u8(u8 *data, u8 reg)
 {
 	int ret;

 	ret = twl_i2c_read_u8(TWL_MODULE_RTC, data, (rtc_reg_map[reg]));
 	if (ret < 0)
 		pr_err("twl_rtc: Could not read TWL"
 		       "register %X - error %d\n", reg, ret);
 	return ret;
 }

 /*
  * Supports 1 byte write to TWL RTC registers.
  */
 static int twl_rtc_write_u8(u8 data, u8 reg)
 {
 	int ret;

 	ret = twl_i2c_write_u8(TWL_MODULE_RTC, data, (rtc_reg_map[reg]));
 	if (ret < 0)
 		pr_err("twl_rtc: Could not write TWL"
 		       "register %X - error %d\n", reg, ret);
 	return ret;
 }

 /*
  * Cache the value for timer/alarm interrupts register; this is
  * only changed by callers holding rtc ops lock (or resume).
  */
 static unsigned char rtc_irq_bits;

 /*
  * Enable 1/second update and/or alarm interrupts.
  */
 static int set_rtc_irq_bit(unsigned char bit)
 {
 	unsigned char val;
 	int ret;

 	/* if the bit is set, return from here */
 	if (rtc_irq_bits & bit)
 		return 0;

 	val = rtc_irq_bits | bit;
 	val &= ~BIT_RTC_INTERRUPTS_REG_EVERY_M;
 	ret = twl_rtc_write_u8(val, REG_RTC_INTERRUPTS_REG);
 	if (ret == 0)
 		rtc_irq_bits = val;

 	return ret;
 }

 /*
  * Disable update and/or alarm interrupts.
  */
 static int mask_rtc_irq_bit(unsigned char bit)
 {
 	unsigned char val;
 	int ret;

 	/* if the bit is clear, return from here */
 	if (!(rtc_irq_bits & bit))
 		return 0;

 	val = rtc_irq_bits & ~bit;
 	ret = twl_rtc_write_u8(val, REG_RTC_INTERRUPTS_REG);
 	if (ret == 0)
 		rtc_irq_bits = val;

 	return ret;
 }

 static int twl_rtc_alarm_irq_enable(struct device *dev, unsigned enabled)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	int irq = platform_get_irq(pdev, 0);
 	static bool twl_rtc_wake_enabled;
 	int ret;

 	if (enabled) {
 		ret = set_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_ALARM_M);
 		if (device_can_wakeup(dev) && !twl_rtc_wake_enabled) {
 			enable_irq_wake(irq);
 			twl_rtc_wake_enabled = true;
 		}
 	} else {
 		ret = mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_ALARM_M);
 		if (twl_rtc_wake_enabled) {
 			disable_irq_wake(irq);
 			twl_rtc_wake_enabled = false;
 		}
 	}

 	return ret;
 }

 /*
  * Gets current TWL RTC time and date parameters.
  *
  * The RTC's time/alarm representation is not what gmtime(3) requires
  * Linux to use:
  *
  *  - Months are 1..12 vs Linux 0-11
  *  - Years are 0..99 vs Linux 1900..N (we assume 21st century)
  */
 static int twl_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	unsigned char rtc_data[ALL_TIME_REGS];
 	int ret;
 	u8 save_control;
 	u8 rtc_control;

 	ret = twl_rtc_read_u8(&save_control, REG_RTC_CTRL_REG);
 	if (ret < 0) {
 		dev_err(dev, "%s: reading CTRL_REG, error %d\n", __func__, ret);
 		return ret;
 	}
 	/* for twl6030/32 make sure BIT_RTC_CTRL_REG_GET_TIME_M is clear */
 	if (twl_class_is_6030()) {
 		if (save_control & BIT_RTC_CTRL_REG_GET_TIME_M) {
 			save_control &= ~BIT_RTC_CTRL_REG_GET_TIME_M;
 			ret = twl_rtc_write_u8(save_control, REG_RTC_CTRL_REG);
 			if (ret < 0) {
 				dev_err(dev, "%s clr GET_TIME, error %d\n",
 					__func__, ret);
 				return ret;
 			}
 		}
 	}

 	/* Copy RTC counting registers to static registers or latches */
 	rtc_control = save_control | BIT_RTC_CTRL_REG_GET_TIME_M;

 	/* for twl6030/32 enable read access to static shadowed registers */
 	if (twl_class_is_6030())
 		rtc_control |= BIT_RTC_CTRL_REG_RTC_V_OPT;

 	ret = twl_rtc_write_u8(rtc_control, REG_RTC_CTRL_REG);
 	if (ret < 0) {
 		dev_err(dev, "%s: writing CTRL_REG, error %d\n", __func__, ret);
 		return ret;
 	}

 	ret = twl_i2c_read(TWL_MODULE_RTC, rtc_data,
 			(rtc_reg_map[REG_SECONDS_REG]), ALL_TIME_REGS);

 	if (ret < 0) {
 		dev_err(dev, "%s: reading data, error %d\n", __func__, ret);
 		return ret;
 	}

 	/* for twl6030 restore original state of rtc control register */
 	if (twl_class_is_6030()) {
 		ret = twl_rtc_write_u8(save_control, REG_RTC_CTRL_REG);
 		if (ret < 0) {
 			dev_err(dev, "%s: restore CTRL_REG, error %d\n",
 				__func__, 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 twl_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	unsigned char save_control;
 	unsigned char rtc_data[ALL_TIME_REGS];
 	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 TC registers */
 	ret = twl_rtc_read_u8(&save_control, REG_RTC_CTRL_REG);
 	if (ret < 0)
 		goto out;

 	save_control &= ~BIT_RTC_CTRL_REG_STOP_RTC_M;
 	ret = twl_rtc_write_u8(save_control, REG_RTC_CTRL_REG);
 	if (ret < 0)
 		goto out;

 	/* update all the time registers in one shot */
 	ret = twl_i2c_write(TWL_MODULE_RTC, rtc_data,
 		(rtc_reg_map[REG_SECONDS_REG]), ALL_TIME_REGS);
 	if (ret < 0) {
 		dev_err(dev, "rtc_set_time error %d\n", ret);
 		goto out;
 	}

 	/* Start back RTC */
 	save_control |= BIT_RTC_CTRL_REG_STOP_RTC_M;
 	ret = twl_rtc_write_u8(save_control, REG_RTC_CTRL_REG);

 out:
 	return ret;
 }

 /*
  * Gets current TWL RTC alarm time.
  */
 static int twl_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
 {
 	unsigned char rtc_data[ALL_TIME_REGS];
 	int ret;

 	ret = twl_i2c_read(TWL_MODULE_RTC, rtc_data,
 			(rtc_reg_map[REG_ALARM_SECONDS_REG]), ALL_TIME_REGS);
 	if (ret < 0) {
 		dev_err(dev, "rtc_read_alarm error %d\n", ret);
 		return ret;
 	}

 	/* some of these fields may be wildcard/"match all" */
 	alm->time.tm_sec = bcd2bin(rtc_data[0]);
 	alm->time.tm_min = bcd2bin(rtc_data[1]);
 	alm->time.tm_hour = bcd2bin(rtc_data[2]);
 	alm->time.tm_mday = bcd2bin(rtc_data[3]);
 	alm->time.tm_mon = bcd2bin(rtc_data[4]) - 1;
 	alm->time.tm_year = bcd2bin(rtc_data[5]) + 100;

 	/* report cached alarm enable state */
 	if (rtc_irq_bits & BIT_RTC_INTERRUPTS_REG_IT_ALARM_M)
 		alm->enabled = 1;

 	return ret;
 }

 static int twl_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
 {
 	unsigned char alarm_data[ALL_TIME_REGS];
 	int ret;

 	ret = twl_rtc_alarm_irq_enable(dev, 0);
 	if (ret)
 		goto out;

 	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 = twl_i2c_write(TWL_MODULE_RTC, alarm_data,
 		(rtc_reg_map[REG_ALARM_SECONDS_REG]), ALL_TIME_REGS);
 	if (ret) {
 		dev_err(dev, "rtc_set_alarm error %d\n", ret);
 		goto out;
 	}

 	if (alm->enabled)
 		ret = twl_rtc_alarm_irq_enable(dev, 1);
 out:
 	return ret;
 }

 static irqreturn_t twl_rtc_interrupt(int irq, void *rtc)
 {
 	unsigned long events;
 	int ret = IRQ_NONE;
 	int res;
 	u8 rd_reg;

 	res = twl_rtc_read_u8(&rd_reg, REG_RTC_STATUS_REG);
 	if (res)
 		goto out;
 	/*
 	 * Figure out source of interrupt: ALARM or TIMER in RTC_STATUS_REG.
 	 * only one (ALARM or RTC) interrupt source may be enabled
 	 * at time, we also could check our results
 	 * by reading RTS_INTERRUPTS_REGISTER[IT_TIMER,IT_ALARM]
 	 */
 	if (rd_reg & BIT_RTC_STATUS_REG_ALARM_M)
 		events = RTC_IRQF | RTC_AF;
 	else
 		events = RTC_IRQF | RTC_PF;

 	res = twl_rtc_write_u8(BIT_RTC_STATUS_REG_ALARM_M,
 				   REG_RTC_STATUS_REG);
 	if (res)
 		goto out;

 	if (twl_class_is_4030()) {
 		/* Clear on Read enabled. RTC_IT bit of TWL4030_INT_PWR_ISR1
 		 * needs 2 reads to clear the interrupt. One read is done in
 		 * do_twl_pwrirq(). Doing the second read, to clear
 		 * the bit.
 		 *
 		 * FIXME the reason PWR_ISR1 needs an extra read is that
 		 * RTC_IF retriggered until we cleared REG_ALARM_M above.
 		 * But re-reading like this is a bad hack; by doing so we
 		 * risk wrongly clearing status for some other IRQ (losing
 		 * the interrupt).  Be smarter about handling RTC_UF ...
 		 */
 		res = twl_i2c_read_u8(TWL4030_MODULE_INT,
 			&rd_reg, TWL4030_INT_PWR_ISR1);
 		if (res)
 			goto out;
 	}

 	/* Notify RTC core on event */
 	rtc_update_irq(rtc, 1, events);

 	ret = IRQ_HANDLED;
 out:
 	return ret;
 }

 static struct rtc_class_ops twl_rtc_ops = {
 	.read_time	= twl_rtc_read_time,
 	.set_time	= twl_rtc_set_time,
 	.read_alarm	= twl_rtc_read_alarm,
 	.set_alarm	= twl_rtc_set_alarm,
 	.alarm_irq_enable = twl_rtc_alarm_irq_enable,
 };

 /*----------------------------------------------------------------------*/

 static int twl_rtc_probe(struct platform_device *pdev)
 {
 	struct rtc_device *rtc;
 	int ret = -EINVAL;
 	int irq = platform_get_irq(pdev, 0);
 	u8 rd_reg;

 	if (irq <= 0)
 		goto out1;

 	/* Initialize the register map */
 	if (twl_class_is_4030())
 		rtc_reg_map = (u8 *)twl4030_rtc_reg_map;
 	else
 		rtc_reg_map = (u8 *)twl6030_rtc_reg_map;

 	ret = twl_rtc_read_u8(&rd_reg, REG_RTC_STATUS_REG);
 	if (ret < 0)
 		goto out1;

 	if (rd_reg & BIT_RTC_STATUS_REG_POWER_UP_M)
 		dev_warn(&pdev->dev, "Power up reset detected.\n");

 	if (rd_reg & BIT_RTC_STATUS_REG_ALARM_M)
 		dev_warn(&pdev->dev, "Pending Alarm interrupt detected.\n");

 	/* Clear RTC Power up reset and pending alarm interrupts */
 	ret = twl_rtc_write_u8(rd_reg, REG_RTC_STATUS_REG);
 	if (ret < 0)
 		goto out1;

 	if (twl_class_is_6030()) {
 		twl6030_interrupt_unmask(TWL6030_RTC_INT_MASK,
 			REG_INT_MSK_LINE_A);
 		twl6030_interrupt_unmask(TWL6030_RTC_INT_MASK,
 			REG_INT_MSK_STS_A);
 	}

 	dev_info(&pdev->dev, "Enabling TWL-RTC\n");
 	ret = twl_rtc_write_u8(BIT_RTC_CTRL_REG_STOP_RTC_M, REG_RTC_CTRL_REG);
 	if (ret < 0)
 		goto out1;

 	/* ensure interrupts are disabled, bootloaders can be strange */
 	ret = twl_rtc_write_u8(0, REG_RTC_INTERRUPTS_REG);
 	if (ret < 0)
 		dev_warn(&pdev->dev, "unable to disable interrupt\n");

 	/* init cached IRQ enable bits */
 	ret = twl_rtc_read_u8(&rtc_irq_bits, REG_RTC_INTERRUPTS_REG);
 	if (ret < 0)
 		goto out1;

 	rtc = rtc_device_register(pdev->name,
 				  &pdev->dev, &twl_rtc_ops, THIS_MODULE);
 	if (IS_ERR(rtc)) {
 		ret = PTR_ERR(rtc);
 		dev_err(&pdev->dev, "can't register RTC device, err %ld\n",
 			PTR_ERR(rtc));
 		goto out1;
 	}

 	ret = request_threaded_irq(irq, NULL, twl_rtc_interrupt,
 				   IRQF_TRIGGER_RISING | IRQF_ONESHOT,
 				   dev_name(&rtc->dev), rtc);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "IRQ is not free.\n");
 		goto out2;
 	}

 	platform_set_drvdata(pdev, rtc);
 	device_init_wakeup(&pdev->dev, 1);
 	return 0;

 out2:
 	rtc_device_unregister(rtc);
 out1:
 	return ret;
 }

 /*
  * Disable all TWL RTC module interrupts.
  * Sets status flag to free.
  */
 static int twl_rtc_remove(struct platform_device *pdev)
 {
 	/* leave rtc running, but disable irqs */
 	struct rtc_device *rtc = platform_get_drvdata(pdev);
 	int irq = platform_get_irq(pdev, 0);

 	mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_ALARM_M);
 	mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_TIMER_M);
 	if (twl_class_is_6030()) {
 		twl6030_interrupt_mask(TWL6030_RTC_INT_MASK,
 			REG_INT_MSK_LINE_A);
 		twl6030_interrupt_mask(TWL6030_RTC_INT_MASK,
 			REG_INT_MSK_STS_A);
 	}


 	free_irq(irq, rtc);

 	rtc_device_unregister(rtc);
 	return 0;
 }

 static void twl_rtc_shutdown(struct platform_device *pdev)
 {
 	/* mask timer interrupts, but leave alarm interrupts on to enable
 	   power-on when alarm is triggered */
 	mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_TIMER_M);
 }

 #ifdef CONFIG_PM_SLEEP
 static unsigned char irqstat;

 static int twl_rtc_suspend(struct device *dev)
 {
 	irqstat = rtc_irq_bits;

 	mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_TIMER_M);
 	return 0;
 }

 static int twl_rtc_resume(struct device *dev)
 {
 	set_rtc_irq_bit(irqstat);
 	return 0;
 }
 #endif

 static SIMPLE_DEV_PM_OPS(twl_rtc_pm_ops, twl_rtc_suspend, twl_rtc_resume);

 #ifdef CONFIG_OF
 static const struct of_device_id twl_rtc_of_match[] = {
 	{.compatible = "ti,twl4030-rtc", },
 	{ },
 };
 MODULE_DEVICE_TABLE(of, twl_rtc_of_match);
 #endif

 MODULE_ALIAS("platform:twl_rtc");

 static struct platform_driver twl4030rtc_driver = {
 	.probe		= twl_rtc_probe,
 	.remove		= twl_rtc_remove,
 	.shutdown	= twl_rtc_shutdown,
 	.driver		= {
 		.owner		= THIS_MODULE,
 		.name		= "twl_rtc",
 		.pm		= &twl_rtc_pm_ops,
 		.of_match_table = of_match_ptr(twl_rtc_of_match),
 	},
 };

 module_platform_driver(twl4030rtc_driver);

 MODULE_AUTHOR("Texas Instruments, MontaVista Software");
 MODULE_LICENSE("GPL");
	/*
	* rtc-twl.c -- TWL Real Time Clock interface
	*
	* Copyright (C) 2007 MontaVista Software, Inc
	* Author: Alexandre Rusev <source@mvista.com>
	*
	* Based on original TI driver twl4030-rtc.c
	* Copyright (C) 2006 Texas Instruments, Inc.
	*
	* Based on rtc-omap.c
	* Copyright (C) 2003 MontaVista Software, Inc.
	* Author: George G. Davis <gdavis@mvista.com> or <source@mvista.com>
	* Copyright (C) 2006 David Brownell
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation; either version
	* 2 of the License, or (at your option) any later version.
	*/

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

	#include <linux/i2c/twl.h>


	/*
	* RTC block register offsets (use TWL_MODULE_RTC)
	*/
	enum {
	REG_SECONDS_REG = 0,
	REG_MINUTES_REG,
	REG_HOURS_REG,
	REG_DAYS_REG,
	REG_MONTHS_REG,
	REG_YEARS_REG,
	REG_WEEKS_REG,

	REG_ALARM_SECONDS_REG,
	REG_ALARM_MINUTES_REG,
	REG_ALARM_HOURS_REG,
	REG_ALARM_DAYS_REG,
	REG_ALARM_MONTHS_REG,
	REG_ALARM_YEARS_REG,

	REG_RTC_CTRL_REG,
	REG_RTC_STATUS_REG,
	REG_RTC_INTERRUPTS_REG,

	REG_RTC_COMP_LSB_REG,
	REG_RTC_COMP_MSB_REG,
	};
	static const u8 twl4030_rtc_reg_map[] = {
	[REG_SECONDS_REG] = 0x00,
	[REG_MINUTES_REG] = 0x01,
	[REG_HOURS_REG] = 0x02,
	[REG_DAYS_REG] = 0x03,
	[REG_MONTHS_REG] = 0x04,
	[REG_YEARS_REG] = 0x05,
	[REG_WEEKS_REG] = 0x06,

	[REG_ALARM_SECONDS_REG] = 0x07,
	[REG_ALARM_MINUTES_REG] = 0x08,
	[REG_ALARM_HOURS_REG] = 0x09,
	[REG_ALARM_DAYS_REG] = 0x0A,
	[REG_ALARM_MONTHS_REG] = 0x0B,
	[REG_ALARM_YEARS_REG] = 0x0C,

	[REG_RTC_CTRL_REG] = 0x0D,
	[REG_RTC_STATUS_REG] = 0x0E,
	[REG_RTC_INTERRUPTS_REG] = 0x0F,

	[REG_RTC_COMP_LSB_REG] = 0x10,
	[REG_RTC_COMP_MSB_REG] = 0x11,
	};
	static const u8 twl6030_rtc_reg_map[] = {
	[REG_SECONDS_REG] = 0x00,
	[REG_MINUTES_REG] = 0x01,
	[REG_HOURS_REG] = 0x02,
	[REG_DAYS_REG] = 0x03,
	[REG_MONTHS_REG] = 0x04,
	[REG_YEARS_REG] = 0x05,
	[REG_WEEKS_REG] = 0x06,

	[REG_ALARM_SECONDS_REG] = 0x08,
	[REG_ALARM_MINUTES_REG] = 0x09,
	[REG_ALARM_HOURS_REG] = 0x0A,
	[REG_ALARM_DAYS_REG] = 0x0B,
	[REG_ALARM_MONTHS_REG] = 0x0C,
	[REG_ALARM_YEARS_REG] = 0x0D,

	[REG_RTC_CTRL_REG] = 0x10,
	[REG_RTC_STATUS_REG] = 0x11,
	[REG_RTC_INTERRUPTS_REG] = 0x12,

	[REG_RTC_COMP_LSB_REG] = 0x13,
	[REG_RTC_COMP_MSB_REG] = 0x14,
	};

	/* RTC_CTRL_REG bitfields */
	#define BIT_RTC_CTRL_REG_STOP_RTC_M 0x01
	#define BIT_RTC_CTRL_REG_ROUND_30S_M 0x02
	#define BIT_RTC_CTRL_REG_AUTO_COMP_M 0x04
	#define BIT_RTC_CTRL_REG_MODE_12_24_M 0x08
	#define BIT_RTC_CTRL_REG_TEST_MODE_M 0x10
	#define BIT_RTC_CTRL_REG_SET_32_COUNTER_M 0x20
	#define BIT_RTC_CTRL_REG_GET_TIME_M 0x40
	#define BIT_RTC_CTRL_REG_RTC_V_OPT 0x80

	/* RTC_STATUS_REG bitfields */
	#define BIT_RTC_STATUS_REG_RUN_M 0x02
	#define BIT_RTC_STATUS_REG_1S_EVENT_M 0x04
	#define BIT_RTC_STATUS_REG_1M_EVENT_M 0x08
	#define BIT_RTC_STATUS_REG_1H_EVENT_M 0x10
	#define BIT_RTC_STATUS_REG_1D_EVENT_M 0x20
	#define BIT_RTC_STATUS_REG_ALARM_M 0x40
	#define BIT_RTC_STATUS_REG_POWER_UP_M 0x80

	/* RTC_INTERRUPTS_REG bitfields */
	#define BIT_RTC_INTERRUPTS_REG_EVERY_M 0x03
	#define BIT_RTC_INTERRUPTS_REG_IT_TIMER_M 0x04
	#define BIT_RTC_INTERRUPTS_REG_IT_ALARM_M 0x08


	/* REG_SECONDS_REG through REG_YEARS_REG is how many registers? */
	#define ALL_TIME_REGS 6

	/----------------------------------------------------------------------/
	static u8 *rtc_reg_map;

	/*
	* Supports 1 byte read from TWL RTC register.
	*/
	static int twl_rtc_read_u8(u8 *data, u8 reg)
	{
	int ret;

	ret = twl_i2c_read_u8(TWL_MODULE_RTC, data, (rtc_reg_map[reg]));
	if (ret < 0)
	pr_err("twl_rtc: Could not read TWL"
	"register %X - error %d\n", reg, ret);
	return ret;
	}

	/*
	* Supports 1 byte write to TWL RTC registers.
	*/
	static int twl_rtc_write_u8(u8 data, u8 reg)
	{
	int ret;

	ret = twl_i2c_write_u8(TWL_MODULE_RTC, data, (rtc_reg_map[reg]));
	if (ret < 0)
	pr_err("twl_rtc: Could not write TWL"
	"register %X - error %d\n", reg, ret);
	return ret;
	}

	/*
	* Cache the value for timer/alarm interrupts register; this is
	* only changed by callers holding rtc ops lock (or resume).
	*/
	static unsigned char rtc_irq_bits;

	/*
	* Enable 1/second update and/or alarm interrupts.
	*/
	static int set_rtc_irq_bit(unsigned char bit)
	{
	unsigned char val;
	int ret;

	/* if the bit is set, return from here */
	if (rtc_irq_bits & bit)
	return 0;

	val = rtc_irq_bits \| bit;
	val &= ~BIT_RTC_INTERRUPTS_REG_EVERY_M;
	ret = twl_rtc_write_u8(val, REG_RTC_INTERRUPTS_REG);
	if (ret == 0)
	rtc_irq_bits = val;

	return ret;
	}

	/*
	* Disable update and/or alarm interrupts.
	*/
	static int mask_rtc_irq_bit(unsigned char bit)
	{
	unsigned char val;
	int ret;

	/* if the bit is clear, return from here */
	if (!(rtc_irq_bits & bit))
	return 0;

	val = rtc_irq_bits & ~bit;
	ret = twl_rtc_write_u8(val, REG_RTC_INTERRUPTS_REG);
	if (ret == 0)
	rtc_irq_bits = val;

	return ret;
	}

	static int twl_rtc_alarm_irq_enable(struct device *dev, unsigned enabled)
	{
	struct platform_device *pdev = to_platform_device(dev);
	int irq = platform_get_irq(pdev, 0);
	static bool twl_rtc_wake_enabled;
	int ret;

	if (enabled) {
	ret = set_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_ALARM_M);
	if (device_can_wakeup(dev) && !twl_rtc_wake_enabled) {
	enable_irq_wake(irq);
	twl_rtc_wake_enabled = true;
	}
	} else {
	ret = mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_ALARM_M);
	if (twl_rtc_wake_enabled) {
	disable_irq_wake(irq);
	twl_rtc_wake_enabled = false;
	}
	}

	return ret;
	}

	/*
	* Gets current TWL RTC time and date parameters.
	*
	* The RTC's time/alarm representation is not what gmtime(3) requires
	* Linux to use:
	*
	* - Months are 1..12 vs Linux 0-11
	* - Years are 0..99 vs Linux 1900..N (we assume 21st century)
	*/
	static int twl_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	unsigned char rtc_data[ALL_TIME_REGS];
	int ret;
	u8 save_control;
	u8 rtc_control;

	ret = twl_rtc_read_u8(&save_control, REG_RTC_CTRL_REG);
	if (ret < 0) {
	dev_err(dev, "%s: reading CTRL_REG, error %d\n", __func__, ret);
	return ret;
	}
	/* for twl6030/32 make sure BIT_RTC_CTRL_REG_GET_TIME_M is clear */
	if (twl_class_is_6030()) {
	if (save_control & BIT_RTC_CTRL_REG_GET_TIME_M) {
	save_control &= ~BIT_RTC_CTRL_REG_GET_TIME_M;
	ret = twl_rtc_write_u8(save_control, REG_RTC_CTRL_REG);
	if (ret < 0) {
	dev_err(dev, "%s clr GET_TIME, error %d\n",
	__func__, ret);
	return ret;
	}
	}
	}

	/* Copy RTC counting registers to static registers or latches */
	rtc_control = save_control \| BIT_RTC_CTRL_REG_GET_TIME_M;

	/* for twl6030/32 enable read access to static shadowed registers */
	if (twl_class_is_6030())
	rtc_control \|= BIT_RTC_CTRL_REG_RTC_V_OPT;

	ret = twl_rtc_write_u8(rtc_control, REG_RTC_CTRL_REG);
	if (ret < 0) {
	dev_err(dev, "%s: writing CTRL_REG, error %d\n", __func__, ret);
	return ret;
	}

	ret = twl_i2c_read(TWL_MODULE_RTC, rtc_data,
	(rtc_reg_map[REG_SECONDS_REG]), ALL_TIME_REGS);

	if (ret < 0) {
	dev_err(dev, "%s: reading data, error %d\n", __func__, ret);
	return ret;
	}

	/* for twl6030 restore original state of rtc control register */
	if (twl_class_is_6030()) {
	ret = twl_rtc_write_u8(save_control, REG_RTC_CTRL_REG);
	if (ret < 0) {
	dev_err(dev, "%s: restore CTRL_REG, error %d\n",
	__func__, 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 twl_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	unsigned char save_control;
	unsigned char rtc_data[ALL_TIME_REGS];
	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 TC registers */
	ret = twl_rtc_read_u8(&save_control, REG_RTC_CTRL_REG);
	if (ret < 0)
	goto out;

	save_control &= ~BIT_RTC_CTRL_REG_STOP_RTC_M;
	ret = twl_rtc_write_u8(save_control, REG_RTC_CTRL_REG);
	if (ret < 0)
	goto out;

	/* update all the time registers in one shot */
	ret = twl_i2c_write(TWL_MODULE_RTC, rtc_data,
	(rtc_reg_map[REG_SECONDS_REG]), ALL_TIME_REGS);
	if (ret < 0) {
	dev_err(dev, "rtc_set_time error %d\n", ret);
	goto out;
	}

	/* Start back RTC */
	save_control \|= BIT_RTC_CTRL_REG_STOP_RTC_M;
	ret = twl_rtc_write_u8(save_control, REG_RTC_CTRL_REG);

	out:
	return ret;
	}

	/*
	* Gets current TWL RTC alarm time.
	*/
	static int twl_rtc_read_alarm(struct device dev, struct rtc_wkalrm alm)
	{
	unsigned char rtc_data[ALL_TIME_REGS];
	int ret;

	ret = twl_i2c_read(TWL_MODULE_RTC, rtc_data,
	(rtc_reg_map[REG_ALARM_SECONDS_REG]), ALL_TIME_REGS);
	if (ret < 0) {
	dev_err(dev, "rtc_read_alarm error %d\n", ret);
	return ret;
	}

	/* some of these fields may be wildcard/"match all" */
	alm->time.tm_sec = bcd2bin(rtc_data[0]);
	alm->time.tm_min = bcd2bin(rtc_data[1]);
	alm->time.tm_hour = bcd2bin(rtc_data[2]);
	alm->time.tm_mday = bcd2bin(rtc_data[3]);
	alm->time.tm_mon = bcd2bin(rtc_data[4]) - 1;
	alm->time.tm_year = bcd2bin(rtc_data[5]) + 100;

	/* report cached alarm enable state */
	if (rtc_irq_bits & BIT_RTC_INTERRUPTS_REG_IT_ALARM_M)
	alm->enabled = 1;

	return ret;
	}

	static int twl_rtc_set_alarm(struct device dev, struct rtc_wkalrm alm)
	{
	unsigned char alarm_data[ALL_TIME_REGS];
	int ret;

	ret = twl_rtc_alarm_irq_enable(dev, 0);
	if (ret)
	goto out;

	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 = twl_i2c_write(TWL_MODULE_RTC, alarm_data,
	(rtc_reg_map[REG_ALARM_SECONDS_REG]), ALL_TIME_REGS);
	if (ret) {
	dev_err(dev, "rtc_set_alarm error %d\n", ret);
	goto out;
	}

	if (alm->enabled)
	ret = twl_rtc_alarm_irq_enable(dev, 1);
	out:
	return ret;
	}

	static irqreturn_t twl_rtc_interrupt(int irq, void *rtc)
	{
	unsigned long events;
	int ret = IRQ_NONE;
	int res;
	u8 rd_reg;

	res = twl_rtc_read_u8(&rd_reg, REG_RTC_STATUS_REG);
	if (res)
	goto out;
	/*
	* Figure out source of interrupt: ALARM or TIMER in RTC_STATUS_REG.
	* only one (ALARM or RTC) interrupt source may be enabled
	* at time, we also could check our results
	* by reading RTS_INTERRUPTS_REGISTER[IT_TIMER,IT_ALARM]
	*/
	if (rd_reg & BIT_RTC_STATUS_REG_ALARM_M)
	events = RTC_IRQF \| RTC_AF;
	else
	events = RTC_IRQF \| RTC_PF;

	res = twl_rtc_write_u8(BIT_RTC_STATUS_REG_ALARM_M,
	REG_RTC_STATUS_REG);
	if (res)
	goto out;

	if (twl_class_is_4030()) {
	/* Clear on Read enabled. RTC_IT bit of TWL4030_INT_PWR_ISR1
	* needs 2 reads to clear the interrupt. One read is done in
	* do_twl_pwrirq(). Doing the second read, to clear
	* the bit.
	*
	* FIXME the reason PWR_ISR1 needs an extra read is that
	* RTC_IF retriggered until we cleared REG_ALARM_M above.
	* But re-reading like this is a bad hack; by doing so we
	* risk wrongly clearing status for some other IRQ (losing
	* the interrupt). Be smarter about handling RTC_UF ...
	*/
	res = twl_i2c_read_u8(TWL4030_MODULE_INT,
	&rd_reg, TWL4030_INT_PWR_ISR1);
	if (res)
	goto out;
	}

	/* Notify RTC core on event */
	rtc_update_irq(rtc, 1, events);

	ret = IRQ_HANDLED;
	out:
	return ret;
	}

	static struct rtc_class_ops twl_rtc_ops = {
	.read_time = twl_rtc_read_time,
	.set_time = twl_rtc_set_time,
	.read_alarm = twl_rtc_read_alarm,
	.set_alarm = twl_rtc_set_alarm,
	.alarm_irq_enable = twl_rtc_alarm_irq_enable,
	};

	/----------------------------------------------------------------------/

	static int twl_rtc_probe(struct platform_device *pdev)
	{
	struct rtc_device *rtc;
	int ret = -EINVAL;
	int irq = platform_get_irq(pdev, 0);
	u8 rd_reg;

	if (irq <= 0)
	goto out1;

	/* Initialize the register map */
	if (twl_class_is_4030())
	rtc_reg_map = (u8 *)twl4030_rtc_reg_map;
	else
	rtc_reg_map = (u8 *)twl6030_rtc_reg_map;

	ret = twl_rtc_read_u8(&rd_reg, REG_RTC_STATUS_REG);
	if (ret < 0)
	goto out1;

	if (rd_reg & BIT_RTC_STATUS_REG_POWER_UP_M)
	dev_warn(&pdev->dev, "Power up reset detected.\n");

	if (rd_reg & BIT_RTC_STATUS_REG_ALARM_M)
	dev_warn(&pdev->dev, "Pending Alarm interrupt detected.\n");

	/* Clear RTC Power up reset and pending alarm interrupts */
	ret = twl_rtc_write_u8(rd_reg, REG_RTC_STATUS_REG);
	if (ret < 0)
	goto out1;

	if (twl_class_is_6030()) {
	twl6030_interrupt_unmask(TWL6030_RTC_INT_MASK,
	REG_INT_MSK_LINE_A);
	twl6030_interrupt_unmask(TWL6030_RTC_INT_MASK,
	REG_INT_MSK_STS_A);
	}

	dev_info(&pdev->dev, "Enabling TWL-RTC\n");
	ret = twl_rtc_write_u8(BIT_RTC_CTRL_REG_STOP_RTC_M, REG_RTC_CTRL_REG);
	if (ret < 0)
	goto out1;

	/* ensure interrupts are disabled, bootloaders can be strange */
	ret = twl_rtc_write_u8(0, REG_RTC_INTERRUPTS_REG);
	if (ret < 0)
	dev_warn(&pdev->dev, "unable to disable interrupt\n");

	/* init cached IRQ enable bits */
	ret = twl_rtc_read_u8(&rtc_irq_bits, REG_RTC_INTERRUPTS_REG);
	if (ret < 0)
	goto out1;

	rtc = rtc_device_register(pdev->name,
	&pdev->dev, &twl_rtc_ops, THIS_MODULE);
	if (IS_ERR(rtc)) {
	ret = PTR_ERR(rtc);
	dev_err(&pdev->dev, "can't register RTC device, err %ld\n",
	PTR_ERR(rtc));
	goto out1;
	}

	ret = request_threaded_irq(irq, NULL, twl_rtc_interrupt,
	IRQF_TRIGGER_RISING \| IRQF_ONESHOT,
	dev_name(&rtc->dev), rtc);
	if (ret < 0) {
	dev_err(&pdev->dev, "IRQ is not free.\n");
	goto out2;
	}

	platform_set_drvdata(pdev, rtc);
	device_init_wakeup(&pdev->dev, 1);
	return 0;

	out2:
	rtc_device_unregister(rtc);
	out1:
	return ret;
	}

	/*
	* Disable all TWL RTC module interrupts.
	* Sets status flag to free.
	*/
	static int twl_rtc_remove(struct platform_device *pdev)
	{
	/* leave rtc running, but disable irqs */
	struct rtc_device *rtc = platform_get_drvdata(pdev);
	int irq = platform_get_irq(pdev, 0);

	mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_ALARM_M);
	mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_TIMER_M);
	if (twl_class_is_6030()) {
	twl6030_interrupt_mask(TWL6030_RTC_INT_MASK,
	REG_INT_MSK_LINE_A);
	twl6030_interrupt_mask(TWL6030_RTC_INT_MASK,
	REG_INT_MSK_STS_A);
	}


	free_irq(irq, rtc);

	rtc_device_unregister(rtc);
	return 0;
	}

	static void twl_rtc_shutdown(struct platform_device *pdev)
	{
	/* mask timer interrupts, but leave alarm interrupts on to enable
	power-on when alarm is triggered */
	mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_TIMER_M);
	}

	#ifdef CONFIG_PM_SLEEP
	static unsigned char irqstat;

	static int twl_rtc_suspend(struct device *dev)
	{
	irqstat = rtc_irq_bits;

	mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_TIMER_M);
	return 0;
	}

	static int twl_rtc_resume(struct device *dev)
	{
	set_rtc_irq_bit(irqstat);
	return 0;
	}
	#endif

	static SIMPLE_DEV_PM_OPS(twl_rtc_pm_ops, twl_rtc_suspend, twl_rtc_resume);

	#ifdef CONFIG_OF
	static const struct of_device_id twl_rtc_of_match[] = {
	{.compatible = "ti,twl4030-rtc", },
	{ },
	};
	MODULE_DEVICE_TABLE(of, twl_rtc_of_match);
	#endif

	MODULE_ALIAS("platform:twl_rtc");

	static struct platform_driver twl4030rtc_driver = {
	.probe = twl_rtc_probe,
	.remove = twl_rtc_remove,
	.shutdown = twl_rtc_shutdown,
	.driver = {
	.owner = THIS_MODULE,
	.name = "twl_rtc",
	.pm = &twl_rtc_pm_ops,
	.of_match_table = of_match_ptr(twl_rtc_of_match),
	},
	};

	module_platform_driver(twl4030rtc_driver);

	MODULE_AUTHOR("Texas Instruments, MontaVista Software");
	MODULE_LICENSE("GPL");