Commit b5b2bdfc authored by Lee Jones's avatar Lee Jones
Browse files

rtc: st: Add new driver for ST's LPC RTC 



ST's Low Power Controller (LPC) controls two devices; watchdog and RTC.
Only one of the devices can be used at any one time.  This is enforced
by the correlating MFD driver.  This portion of the driver-set controls
the Real Time Clock.

Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: default avatarLee Jones <lee.jones@linaro.org>
parent 5cb69745

drivers/rtc/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -1510,6 +1510,17 @@ config RTC_DRV_SIRFSOC 
	  Say "yes" here to support the real time clock on SiRF SOC chips.

	  This driver can also be built as a module called rtc-sirfsoc.



config RTC_DRV_ST_LPC

	tristate "STMicroelectronics LPC RTC"

	depends on ARCH_STI

	depends on OF

	help

	  Say Y here to include STMicroelectronics Low Power Controller

	  (LPC) based RTC support.



	  To compile this driver as a module, choose M here: the

	  module will be called rtc-st-lpc.



config RTC_DRV_MOXART

	tristate "MOXA ART RTC"

	depends on ARCH_MOXART || COMPILE_TEST

drivers/rtc/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -153,4 +153,5 @@ obj-$(CONFIG_RTC_DRV_WM8350) += rtc-wm8350.o 
obj-$(CONFIG_RTC_DRV_X1205)	+= rtc-x1205.o

obj-$(CONFIG_RTC_DRV_XGENE)	+= rtc-xgene.o

obj-$(CONFIG_RTC_DRV_SIRFSOC)	+= rtc-sirfsoc.o

obj-$(CONFIG_RTC_DRV_ST_LPC)	+= rtc-st-lpc.o

obj-$(CONFIG_RTC_DRV_MOXART)	+= rtc-moxart.o

drivers/rtc/rtc-st-lpc.c

0 → 100644
+354 −0
Original line number Diff line number Diff line 
/*

 * rtc-st-lpc.c - ST's LPC RTC, powered by the Low Power Timer

 *

 * Copyright (C) 2014 STMicroelectronics Limited

 *

 * Author: David Paris <david.paris@st.com> for STMicroelectronics

 *         Lee Jones <lee.jones@linaro.org> for STMicroelectronics

 *

 * Based on the original driver written by Stuart Menefy.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public Licence

 * as published by the Free Software Foundation; either version

 * 2 of the Licence, or (at your option) any later version.

 */



#include <linux/clk.h>

#include <linux/delay.h>

#include <linux/init.h>

#include <linux/io.h>

#include <linux/irq.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/of.h>

#include <linux/of_irq.h>

#include <linux/platform_device.h>

#include <linux/rtc.h>



#include <dt-bindings/mfd/st-lpc.h>



/* Low Power Timer */

#define LPC_LPT_LSB_OFF		0x400

#define LPC_LPT_MSB_OFF		0x404

#define LPC_LPT_START_OFF	0x408



/* Low Power Alarm */

#define LPC_LPA_LSB_OFF		0x410

#define LPC_LPA_MSB_OFF		0x414

#define LPC_LPA_START_OFF	0x418



/* LPC as WDT */

#define LPC_WDT_OFF		0x510

#define LPC_WDT_FLAG_OFF	0x514



struct st_rtc {

	struct rtc_device *rtc_dev;

	struct rtc_wkalrm alarm;

	struct resource *res;

	struct clk *clk;

	unsigned long clkrate;

	void __iomem *ioaddr;

	bool irq_enabled:1;

	spinlock_t lock;

	short irq;

};



static void st_rtc_set_hw_alarm(struct st_rtc *rtc,

				unsigned long msb, unsigned long  lsb)

{

	unsigned long flags;



	spin_lock_irqsave(&rtc->lock, flags);



	writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);



	writel_relaxed(msb, rtc->ioaddr + LPC_LPA_MSB_OFF);

	writel_relaxed(lsb, rtc->ioaddr + LPC_LPA_LSB_OFF);

	writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF);



	writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);



	spin_unlock_irqrestore(&rtc->lock, flags);

}



static irqreturn_t st_rtc_handler(int this_irq, void *data)

{

	struct st_rtc *rtc = (struct st_rtc *)data;



	rtc_update_irq(rtc->rtc_dev, 1, RTC_AF);



	return IRQ_HANDLED;

}



static int st_rtc_read_time(struct device *dev, struct rtc_time *tm)

{

	struct st_rtc *rtc = dev_get_drvdata(dev);

	unsigned long lpt_lsb, lpt_msb;

	unsigned long long lpt;

	unsigned long flags;



	spin_lock_irqsave(&rtc->lock, flags);



	do {

		lpt_msb = readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF);

		lpt_lsb = readl_relaxed(rtc->ioaddr + LPC_LPT_LSB_OFF);

	} while (readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF) != lpt_msb);



	spin_unlock_irqrestore(&rtc->lock, flags);



	lpt = ((unsigned long long)lpt_msb << 32) | lpt_lsb;

	do_div(lpt, rtc->clkrate);

	rtc_time_to_tm(lpt, tm);



	return 0;

}



static int st_rtc_set_time(struct device *dev, struct rtc_time *tm)

{

	struct st_rtc *rtc = dev_get_drvdata(dev);

	unsigned long long lpt;

	unsigned long secs, flags;

	int ret;



	ret = rtc_tm_to_time(tm, &secs);

	if (ret)

		return ret;



	lpt = (unsigned long long)secs * rtc->clkrate;



	spin_lock_irqsave(&rtc->lock, flags);



	writel_relaxed(lpt >> 32, rtc->ioaddr + LPC_LPT_MSB_OFF);

	writel_relaxed(lpt, rtc->ioaddr + LPC_LPT_LSB_OFF);

	writel_relaxed(1, rtc->ioaddr + LPC_LPT_START_OFF);



	spin_unlock_irqrestore(&rtc->lock, flags);



	return 0;

}



static int st_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)

{

	struct st_rtc *rtc = dev_get_drvdata(dev);

	unsigned long flags;



	spin_lock_irqsave(&rtc->lock, flags);



	memcpy(wkalrm, &rtc->alarm, sizeof(struct rtc_wkalrm));



	spin_unlock_irqrestore(&rtc->lock, flags);



	return 0;

}



static int st_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)

{

	struct st_rtc *rtc = dev_get_drvdata(dev);



	if (enabled && !rtc->irq_enabled) {

		enable_irq(rtc->irq);

		rtc->irq_enabled = true;

	} else if (!enabled && rtc->irq_enabled) {

		disable_irq(rtc->irq);

		rtc->irq_enabled = false;

	}



	return 0;

}



static int st_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)

{

	struct st_rtc *rtc = dev_get_drvdata(dev);

	struct rtc_time now;

	unsigned long now_secs;

	unsigned long alarm_secs;

	unsigned long long lpa;



	st_rtc_read_time(dev, &now);

	rtc_tm_to_time(&now, &now_secs);

	rtc_tm_to_time(&t->time, &alarm_secs);



	/* Invalid alarm time */

	if (now_secs > alarm_secs)

		return -EINVAL;



	memcpy(&rtc->alarm, t, sizeof(struct rtc_wkalrm));



	/* Now many secs to fire */

	alarm_secs -= now_secs;

	lpa = (unsigned long long)alarm_secs * rtc->clkrate;



	st_rtc_set_hw_alarm(rtc, lpa >> 32, lpa);

	st_rtc_alarm_irq_enable(dev, t->enabled);



	return 0;

}



static struct rtc_class_ops st_rtc_ops = {

	.read_time		= st_rtc_read_time,

	.set_time		= st_rtc_set_time,

	.read_alarm		= st_rtc_read_alarm,

	.set_alarm		= st_rtc_set_alarm,

	.alarm_irq_enable	= st_rtc_alarm_irq_enable,

};



static int st_rtc_probe(struct platform_device *pdev)

{

	struct device_node *np = pdev->dev.of_node;

	struct st_rtc *rtc;

	struct resource *res;

	struct rtc_time tm_check;

	uint32_t mode;

	int ret = 0;



	ret = of_property_read_u32(np, "st,lpc-mode", &mode);

	if (ret) {

		dev_err(&pdev->dev, "An LPC mode must be provided\n");

		return -EINVAL;

	}



	/* LPC can either run in RTC or WDT mode */

	if (mode != ST_LPC_MODE_RTC)

		return -ENODEV;



	rtc = devm_kzalloc(&pdev->dev, sizeof(struct st_rtc), GFP_KERNEL);

	if (!rtc)

		return -ENOMEM;



	spin_lock_init(&rtc->lock);



	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	rtc->ioaddr = devm_ioremap_resource(&pdev->dev, res);

	if (IS_ERR(rtc->ioaddr))

		return PTR_ERR(rtc->ioaddr);



	rtc->irq = irq_of_parse_and_map(np, 0);

	if (!rtc->irq) {

		dev_err(&pdev->dev, "IRQ missing or invalid\n");

		return -EINVAL;

	}



	ret = devm_request_irq(&pdev->dev, rtc->irq, st_rtc_handler, 0,

			       pdev->name, rtc);

	if (ret) {

		dev_err(&pdev->dev, "Failed to request irq %i\n", rtc->irq);

		return ret;

	}



	enable_irq_wake(rtc->irq);

	disable_irq(rtc->irq);



	rtc->clk = clk_get(&pdev->dev, NULL);

	if (IS_ERR(rtc->clk)) {

		dev_err(&pdev->dev, "Unable to request clock\n");

		return PTR_ERR(rtc->clk);

	}



	clk_prepare_enable(rtc->clk);



	rtc->clkrate = clk_get_rate(rtc->clk);

	if (!rtc->clkrate) {

		dev_err(&pdev->dev, "Unable to fetch clock rate\n");

		return -EINVAL;

	}



	device_set_wakeup_capable(&pdev->dev, 1);



	platform_set_drvdata(pdev, rtc);



	/*

	 * The RTC-LPC is able to manage date.year > 2038

	 * but currently the kernel can not manage this date!

	 * If the RTC-LPC has a date.year > 2038 then

	 * it's set to the epoch "Jan 1st 2000"

	 */

	st_rtc_read_time(&pdev->dev, &tm_check);



	if (tm_check.tm_year >=  (2038 - 1900)) {

		memset(&tm_check, 0, sizeof(tm_check));

		tm_check.tm_year = 100;

		tm_check.tm_mday = 1;

		st_rtc_set_time(&pdev->dev, &tm_check);

	}



	rtc->rtc_dev = rtc_device_register("st-lpc-rtc", &pdev->dev,

					   &st_rtc_ops, THIS_MODULE);

	if (IS_ERR(rtc->rtc_dev)) {

		clk_disable_unprepare(rtc->clk);

		return PTR_ERR(rtc->rtc_dev);

	}



	return 0;

}



static int st_rtc_remove(struct platform_device *pdev)

{

	struct st_rtc *rtc = platform_get_drvdata(pdev);



	if (likely(rtc->rtc_dev))

		rtc_device_unregister(rtc->rtc_dev);



	return 0;

}



#ifdef CONFIG_PM_SLEEP

static int st_rtc_suspend(struct device *dev)

{

	struct st_rtc *rtc = dev_get_drvdata(dev);



	if (device_may_wakeup(dev))

		return 0;



	writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);

	writel_relaxed(0, rtc->ioaddr + LPC_LPA_START_OFF);

	writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);



	return 0;

}



static int st_rtc_resume(struct device *dev)

{

	struct st_rtc *rtc = dev_get_drvdata(dev);



	rtc_alarm_irq_enable(rtc->rtc_dev, 0);



	/*

	 * clean 'rtc->alarm' to allow a new

	 * .set_alarm to the upper RTC layer

	 */

	memset(&rtc->alarm, 0, sizeof(struct rtc_wkalrm));



	writel_relaxed(0, rtc->ioaddr + LPC_LPA_MSB_OFF);

	writel_relaxed(0, rtc->ioaddr + LPC_LPA_LSB_OFF);

	writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF);

	writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF);

	writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF);



	return 0;

}

#endif



static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume);



static const struct of_device_id st_rtc_match[] = {

	{ .compatible = "st,stih407-lpc" },

	{}

};

MODULE_DEVICE_TABLE(of, st_rtc_match);



static struct platform_driver st_rtc_platform_driver = {

	.driver = {

		.name = "st-lpc-rtc",

		.pm = &st_rtc_pm_ops,

		.of_match_table = st_rtc_match,

	},

	.probe = st_rtc_probe,

	.remove = st_rtc_remove,

};



module_platform_driver(st_rtc_platform_driver);



MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver");

MODULE_AUTHOR("David Paris <david.paris@st.com>");

MODULE_LICENSE("GPL");

CRA Git | Maintained and supported by SUSTech CRA and CCSE