// SPDX-License-Identifier: GPL-2.0-or-later
/*
* rtc-st-lpc.c - ST's LPC RTC, powered by the Low Power Timer
*
* Copyright (C) 2014 STMicroelectronics Limited
*
* Author: David Paris <[email protected]> for STMicroelectronics
* Lee Jones <[email protected]> for STMicroelectronics
*
* Based on the original driver written by Stuart Menefy.
*/
#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 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_time64_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, secs;
unsigned long flags;
secs = rtc_tm_to_time64(tm);
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 long now_secs;
unsigned long long alarm_secs;
unsigned long long lpa;
st_rtc_read_time(dev, &now);
now_secs = rtc_tm_to_time64(&now);
alarm_secs = rtc_tm_to_time64(&t->time);
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 const 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;
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 as a Clocksource or 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;
rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
if (IS_ERR(rtc->rtc_dev))
return PTR_ERR(rtc->rtc_dev);
spin_lock_init(&rtc->lock);
rtc->ioaddr = devm_platform_ioremap_resource(pdev, 0);
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 = devm_clk_get_enabled(&pdev->dev, NULL);
if (IS_ERR(rtc->clk))
return dev_err_probe(&pdev->dev, PTR_ERR(rtc->clk),
"Unable to request clock\n");
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);
rtc->rtc_dev->ops = &st_rtc_ops;
rtc->rtc_dev->range_max = U64_MAX;
do_div(rtc->rtc_dev->range_max, rtc->clkrate);
ret = devm_rtc_register_device(rtc->rtc_dev);
if (ret)
return ret;
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,
};
module_platform_driver(st_rtc_platform_driver);
MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver");
MODULE_AUTHOR("David Paris <[email protected]>");
MODULE_LICENSE("GPL");
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