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linux/drivers/rtc/rtc-stm32.c

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) STMicroelectronics 2017
* Author: Amelie Delaunay <amelie.delaunay@st.com>
*/
#include <linux/bcd.h>
#include <linux/clk.h>
#include <linux/iopoll.h>
#include <linux/ioport.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/pm_wakeirq.h>
#include <linux/regmap.h>
#include <linux/rtc.h>
#define DRIVER_NAME "stm32_rtc"
/* STM32_RTC_TR bit fields */
#define STM32_RTC_TR_SEC_SHIFT 0
#define STM32_RTC_TR_SEC GENMASK(6, 0)
#define STM32_RTC_TR_MIN_SHIFT 8
#define STM32_RTC_TR_MIN GENMASK(14, 8)
#define STM32_RTC_TR_HOUR_SHIFT 16
#define STM32_RTC_TR_HOUR GENMASK(21, 16)
/* STM32_RTC_DR bit fields */
#define STM32_RTC_DR_DATE_SHIFT 0
#define STM32_RTC_DR_DATE GENMASK(5, 0)
#define STM32_RTC_DR_MONTH_SHIFT 8
#define STM32_RTC_DR_MONTH GENMASK(12, 8)
#define STM32_RTC_DR_WDAY_SHIFT 13
#define STM32_RTC_DR_WDAY GENMASK(15, 13)
#define STM32_RTC_DR_YEAR_SHIFT 16
#define STM32_RTC_DR_YEAR GENMASK(23, 16)
/* STM32_RTC_CR bit fields */
#define STM32_RTC_CR_FMT BIT(6)
#define STM32_RTC_CR_ALRAE BIT(8)
#define STM32_RTC_CR_ALRAIE BIT(12)
/* STM32_RTC_ISR/STM32_RTC_ICSR bit fields */
#define STM32_RTC_ISR_ALRAWF BIT(0)
#define STM32_RTC_ISR_INITS BIT(4)
#define STM32_RTC_ISR_RSF BIT(5)
#define STM32_RTC_ISR_INITF BIT(6)
#define STM32_RTC_ISR_INIT BIT(7)
#define STM32_RTC_ISR_ALRAF BIT(8)
/* STM32_RTC_PRER bit fields */
#define STM32_RTC_PRER_PRED_S_SHIFT 0
#define STM32_RTC_PRER_PRED_S GENMASK(14, 0)
#define STM32_RTC_PRER_PRED_A_SHIFT 16
#define STM32_RTC_PRER_PRED_A GENMASK(22, 16)
/* STM32_RTC_ALRMAR and STM32_RTC_ALRMBR bit fields */
#define STM32_RTC_ALRMXR_SEC_SHIFT 0
#define STM32_RTC_ALRMXR_SEC GENMASK(6, 0)
#define STM32_RTC_ALRMXR_SEC_MASK BIT(7)
#define STM32_RTC_ALRMXR_MIN_SHIFT 8
#define STM32_RTC_ALRMXR_MIN GENMASK(14, 8)
#define STM32_RTC_ALRMXR_MIN_MASK BIT(15)
#define STM32_RTC_ALRMXR_HOUR_SHIFT 16
#define STM32_RTC_ALRMXR_HOUR GENMASK(21, 16)
#define STM32_RTC_ALRMXR_PM BIT(22)
#define STM32_RTC_ALRMXR_HOUR_MASK BIT(23)
#define STM32_RTC_ALRMXR_DATE_SHIFT 24
#define STM32_RTC_ALRMXR_DATE GENMASK(29, 24)
#define STM32_RTC_ALRMXR_WDSEL BIT(30)
#define STM32_RTC_ALRMXR_WDAY_SHIFT 24
#define STM32_RTC_ALRMXR_WDAY GENMASK(27, 24)
#define STM32_RTC_ALRMXR_DATE_MASK BIT(31)
/* STM32_RTC_SR/_SCR bit fields */
#define STM32_RTC_SR_ALRA BIT(0)
/* STM32_RTC_VERR bit fields */
#define STM32_RTC_VERR_MINREV_SHIFT 0
#define STM32_RTC_VERR_MINREV GENMASK(3, 0)
#define STM32_RTC_VERR_MAJREV_SHIFT 4
#define STM32_RTC_VERR_MAJREV GENMASK(7, 4)
/* STM32_RTC_WPR key constants */
#define RTC_WPR_1ST_KEY 0xCA
#define RTC_WPR_2ND_KEY 0x53
#define RTC_WPR_WRONG_KEY 0xFF
/* Max STM32 RTC register offset is 0x3FC */
#define UNDEF_REG 0xFFFF
struct stm32_rtc;
struct stm32_rtc_registers {
u16 tr;
u16 dr;
u16 cr;
u16 isr;
u16 prer;
u16 alrmar;
u16 wpr;
u16 sr;
u16 scr;
u16 verr;
};
struct stm32_rtc_events {
u32 alra;
};
struct stm32_rtc_data {
const struct stm32_rtc_registers regs;
const struct stm32_rtc_events events;
void (*clear_events)(struct stm32_rtc *rtc, unsigned int flags);
bool has_pclk;
bool need_dbp;
bool has_wakeirq;
};
struct stm32_rtc {
struct rtc_device *rtc_dev;
void __iomem *base;
struct regmap *dbp;
unsigned int dbp_reg;
unsigned int dbp_mask;
struct clk *pclk;
struct clk *rtc_ck;
const struct stm32_rtc_data *data;
int irq_alarm;
int wakeirq_alarm;
};
static void stm32_rtc_wpr_unlock(struct stm32_rtc *rtc)
{
const struct stm32_rtc_registers *regs = &rtc->data->regs;
writel_relaxed(RTC_WPR_1ST_KEY, rtc->base + regs->wpr);
writel_relaxed(RTC_WPR_2ND_KEY, rtc->base + regs->wpr);
}
static void stm32_rtc_wpr_lock(struct stm32_rtc *rtc)
{
const struct stm32_rtc_registers *regs = &rtc->data->regs;
writel_relaxed(RTC_WPR_WRONG_KEY, rtc->base + regs->wpr);
}
static int stm32_rtc_enter_init_mode(struct stm32_rtc *rtc)
{
const struct stm32_rtc_registers *regs = &rtc->data->regs;
unsigned int isr = readl_relaxed(rtc->base + regs->isr);
if (!(isr & STM32_RTC_ISR_INITF)) {
isr |= STM32_RTC_ISR_INIT;
writel_relaxed(isr, rtc->base + regs->isr);
/*
* It takes around 2 rtc_ck clock cycles to enter in
* initialization phase mode (and have INITF flag set). As
* slowest rtc_ck frequency may be 32kHz and highest should be
* 1MHz, we poll every 10 us with a timeout of 100ms.
*/
return readl_relaxed_poll_timeout_atomic(
rtc->base + regs->isr,
isr, (isr & STM32_RTC_ISR_INITF),
10, 100000);
}
return 0;
}
static void stm32_rtc_exit_init_mode(struct stm32_rtc *rtc)
{
const struct stm32_rtc_registers *regs = &rtc->data->regs;
unsigned int isr = readl_relaxed(rtc->base + regs->isr);
isr &= ~STM32_RTC_ISR_INIT;
writel_relaxed(isr, rtc->base + regs->isr);
}
static int stm32_rtc_wait_sync(struct stm32_rtc *rtc)
{
const struct stm32_rtc_registers *regs = &rtc->data->regs;
unsigned int isr = readl_relaxed(rtc->base + regs->isr);
isr &= ~STM32_RTC_ISR_RSF;
writel_relaxed(isr, rtc->base + regs->isr);
/*
* Wait for RSF to be set to ensure the calendar registers are
* synchronised, it takes around 2 rtc_ck clock cycles
*/
return readl_relaxed_poll_timeout_atomic(rtc->base + regs->isr,
isr,
(isr & STM32_RTC_ISR_RSF),
10, 100000);
}
static void stm32_rtc_clear_event_flags(struct stm32_rtc *rtc,
unsigned int flags)
{
rtc->data->clear_events(rtc, flags);
}
static irqreturn_t stm32_rtc_alarm_irq(int irq, void *dev_id)
{
struct stm32_rtc *rtc = (struct stm32_rtc *)dev_id;
const struct stm32_rtc_registers *regs = &rtc->data->regs;
const struct stm32_rtc_events *evts = &rtc->data->events;
unsigned int status, cr;
mutex_lock(&rtc->rtc_dev->ops_lock);
status = readl_relaxed(rtc->base + regs->sr);
cr = readl_relaxed(rtc->base + regs->cr);
if ((status & evts->alra) &&
(cr & STM32_RTC_CR_ALRAIE)) {
/* Alarm A flag - Alarm interrupt */
dev_dbg(&rtc->rtc_dev->dev, "Alarm occurred\n");
/* Pass event to the kernel */
rtc_update_irq(rtc->rtc_dev, 1, RTC_IRQF | RTC_AF);
/* Clear event flags, otherwise new events won't be received */
stm32_rtc_clear_event_flags(rtc, evts->alra);
}
mutex_unlock(&rtc->rtc_dev->ops_lock);
return IRQ_HANDLED;
}
/* Convert rtc_time structure from bin to bcd format */
static void tm2bcd(struct rtc_time *tm)
{
tm->tm_sec = bin2bcd(tm->tm_sec);
tm->tm_min = bin2bcd(tm->tm_min);
tm->tm_hour = bin2bcd(tm->tm_hour);
tm->tm_mday = bin2bcd(tm->tm_mday);
tm->tm_mon = bin2bcd(tm->tm_mon + 1);
tm->tm_year = bin2bcd(tm->tm_year - 100);
/*
* Number of days since Sunday
* - on kernel side, 0=Sunday...6=Saturday
* - on rtc side, 0=invalid,1=Monday...7=Sunday
*/
tm->tm_wday = (!tm->tm_wday) ? 7 : tm->tm_wday;
}
/* Convert rtc_time structure from bcd to bin format */
static void bcd2tm(struct rtc_time *tm)
{
tm->tm_sec = bcd2bin(tm->tm_sec);
tm->tm_min = bcd2bin(tm->tm_min);
tm->tm_hour = bcd2bin(tm->tm_hour);
tm->tm_mday = bcd2bin(tm->tm_mday);
tm->tm_mon = bcd2bin(tm->tm_mon) - 1;
tm->tm_year = bcd2bin(tm->tm_year) + 100;
/*
* Number of days since Sunday
* - on kernel side, 0=Sunday...6=Saturday
* - on rtc side, 0=invalid,1=Monday...7=Sunday
*/
tm->tm_wday %= 7;
}
static int stm32_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct stm32_rtc *rtc = dev_get_drvdata(dev);
const struct stm32_rtc_registers *regs = &rtc->data->regs;
unsigned int tr, dr;
/* Time and Date in BCD format */
tr = readl_relaxed(rtc->base + regs->tr);
dr = readl_relaxed(rtc->base + regs->dr);
tm->tm_sec = (tr & STM32_RTC_TR_SEC) >> STM32_RTC_TR_SEC_SHIFT;
tm->tm_min = (tr & STM32_RTC_TR_MIN) >> STM32_RTC_TR_MIN_SHIFT;
tm->tm_hour = (tr & STM32_RTC_TR_HOUR) >> STM32_RTC_TR_HOUR_SHIFT;
tm->tm_mday = (dr & STM32_RTC_DR_DATE) >> STM32_RTC_DR_DATE_SHIFT;
tm->tm_mon = (dr & STM32_RTC_DR_MONTH) >> STM32_RTC_DR_MONTH_SHIFT;
tm->tm_year = (dr & STM32_RTC_DR_YEAR) >> STM32_RTC_DR_YEAR_SHIFT;
tm->tm_wday = (dr & STM32_RTC_DR_WDAY) >> STM32_RTC_DR_WDAY_SHIFT;
/* We don't report tm_yday and tm_isdst */
bcd2tm(tm);
return 0;
}
static int stm32_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct stm32_rtc *rtc = dev_get_drvdata(dev);
const struct stm32_rtc_registers *regs = &rtc->data->regs;
unsigned int tr, dr;
int ret = 0;
tm2bcd(tm);
/* Time in BCD format */
tr = ((tm->tm_sec << STM32_RTC_TR_SEC_SHIFT) & STM32_RTC_TR_SEC) |
((tm->tm_min << STM32_RTC_TR_MIN_SHIFT) & STM32_RTC_TR_MIN) |
((tm->tm_hour << STM32_RTC_TR_HOUR_SHIFT) & STM32_RTC_TR_HOUR);
/* Date in BCD format */
dr = ((tm->tm_mday << STM32_RTC_DR_DATE_SHIFT) & STM32_RTC_DR_DATE) |
((tm->tm_mon << STM32_RTC_DR_MONTH_SHIFT) & STM32_RTC_DR_MONTH) |
((tm->tm_year << STM32_RTC_DR_YEAR_SHIFT) & STM32_RTC_DR_YEAR) |
((tm->tm_wday << STM32_RTC_DR_WDAY_SHIFT) & STM32_RTC_DR_WDAY);
stm32_rtc_wpr_unlock(rtc);
ret = stm32_rtc_enter_init_mode(rtc);
if (ret) {
dev_err(dev, "Can't enter in init mode. Set time aborted.\n");
goto end;
}
writel_relaxed(tr, rtc->base + regs->tr);
writel_relaxed(dr, rtc->base + regs->dr);
stm32_rtc_exit_init_mode(rtc);
ret = stm32_rtc_wait_sync(rtc);
end:
stm32_rtc_wpr_lock(rtc);
return ret;
}
static int stm32_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct stm32_rtc *rtc = dev_get_drvdata(dev);
const struct stm32_rtc_registers *regs = &rtc->data->regs;
const struct stm32_rtc_events *evts = &rtc->data->events;
struct rtc_time *tm = &alrm->time;
unsigned int alrmar, cr, status;
alrmar = readl_relaxed(rtc->base + regs->alrmar);
cr = readl_relaxed(rtc->base + regs->cr);
status = readl_relaxed(rtc->base + regs->sr);
if (alrmar & STM32_RTC_ALRMXR_DATE_MASK) {
/*
* Date/day doesn't matter in Alarm comparison so alarm
* triggers every day
*/
tm->tm_mday = -1;
tm->tm_wday = -1;
} else {
if (alrmar & STM32_RTC_ALRMXR_WDSEL) {
/* Alarm is set to a day of week */
tm->tm_mday = -1;
tm->tm_wday = (alrmar & STM32_RTC_ALRMXR_WDAY) >>
STM32_RTC_ALRMXR_WDAY_SHIFT;
tm->tm_wday %= 7;
} else {
/* Alarm is set to a day of month */
tm->tm_wday = -1;
tm->tm_mday = (alrmar & STM32_RTC_ALRMXR_DATE) >>
STM32_RTC_ALRMXR_DATE_SHIFT;
}
}
if (alrmar & STM32_RTC_ALRMXR_HOUR_MASK) {
/* Hours don't matter in Alarm comparison */
tm->tm_hour = -1;
} else {
tm->tm_hour = (alrmar & STM32_RTC_ALRMXR_HOUR) >>
STM32_RTC_ALRMXR_HOUR_SHIFT;
if (alrmar & STM32_RTC_ALRMXR_PM)
tm->tm_hour += 12;
}
if (alrmar & STM32_RTC_ALRMXR_MIN_MASK) {
/* Minutes don't matter in Alarm comparison */
tm->tm_min = -1;
} else {
tm->tm_min = (alrmar & STM32_RTC_ALRMXR_MIN) >>
STM32_RTC_ALRMXR_MIN_SHIFT;
}
if (alrmar & STM32_RTC_ALRMXR_SEC_MASK) {
/* Seconds don't matter in Alarm comparison */
tm->tm_sec = -1;
} else {
tm->tm_sec = (alrmar & STM32_RTC_ALRMXR_SEC) >>
STM32_RTC_ALRMXR_SEC_SHIFT;
}
bcd2tm(tm);
alrm->enabled = (cr & STM32_RTC_CR_ALRAE) ? 1 : 0;
alrm->pending = (status & evts->alra) ? 1 : 0;
return 0;
}
static int stm32_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct stm32_rtc *rtc = dev_get_drvdata(dev);
const struct stm32_rtc_registers *regs = &rtc->data->regs;
const struct stm32_rtc_events *evts = &rtc->data->events;
unsigned int cr;
cr = readl_relaxed(rtc->base + regs->cr);
stm32_rtc_wpr_unlock(rtc);
/* We expose Alarm A to the kernel */
if (enabled)
cr |= (STM32_RTC_CR_ALRAIE | STM32_RTC_CR_ALRAE);
else
cr &= ~(STM32_RTC_CR_ALRAIE | STM32_RTC_CR_ALRAE);
writel_relaxed(cr, rtc->base + regs->cr);
/* Clear event flags, otherwise new events won't be received */
stm32_rtc_clear_event_flags(rtc, evts->alra);
stm32_rtc_wpr_lock(rtc);
return 0;
}
static int stm32_rtc_valid_alrm(struct stm32_rtc *rtc, struct rtc_time *tm)
{
const struct stm32_rtc_registers *regs = &rtc->data->regs;
int cur_day, cur_mon, cur_year, cur_hour, cur_min, cur_sec;
unsigned int dr = readl_relaxed(rtc->base + regs->dr);
unsigned int tr = readl_relaxed(rtc->base + regs->tr);
cur_day = (dr & STM32_RTC_DR_DATE) >> STM32_RTC_DR_DATE_SHIFT;
cur_mon = (dr & STM32_RTC_DR_MONTH) >> STM32_RTC_DR_MONTH_SHIFT;
cur_year = (dr & STM32_RTC_DR_YEAR) >> STM32_RTC_DR_YEAR_SHIFT;
cur_sec = (tr & STM32_RTC_TR_SEC) >> STM32_RTC_TR_SEC_SHIFT;
cur_min = (tr & STM32_RTC_TR_MIN) >> STM32_RTC_TR_MIN_SHIFT;
cur_hour = (tr & STM32_RTC_TR_HOUR) >> STM32_RTC_TR_HOUR_SHIFT;
/*
* Assuming current date is M-D-Y H:M:S.
* RTC alarm can't be set on a specific month and year.
* So the valid alarm range is:
* M-D-Y H:M:S < alarm <= (M+1)-D-Y H:M:S
* with a specific case for December...
*/
if ((((tm->tm_year > cur_year) &&
(tm->tm_mon == 0x1) && (cur_mon == 0x12)) ||
((tm->tm_year == cur_year) &&
(tm->tm_mon <= cur_mon + 1))) &&
((tm->tm_mday > cur_day) ||
((tm->tm_mday == cur_day) &&
((tm->tm_hour > cur_hour) ||
((tm->tm_hour == cur_hour) && (tm->tm_min > cur_min)) ||
((tm->tm_hour == cur_hour) && (tm->tm_min == cur_min) &&
(tm->tm_sec >= cur_sec))))))
return 0;
return -EINVAL;
}
static int stm32_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct stm32_rtc *rtc = dev_get_drvdata(dev);
const struct stm32_rtc_registers *regs = &rtc->data->regs;
struct rtc_time *tm = &alrm->time;
unsigned int cr, isr, alrmar;
int ret = 0;
tm2bcd(tm);
/*
* RTC alarm can't be set on a specific date, unless this date is
* up to the same day of month next month.
*/
if (stm32_rtc_valid_alrm(rtc, tm) < 0) {
dev_err(dev, "Alarm can be set only on upcoming month.\n");
return -EINVAL;
}
alrmar = 0;
/* tm_year and tm_mon are not used because not supported by RTC */
alrmar |= (tm->tm_mday << STM32_RTC_ALRMXR_DATE_SHIFT) &
STM32_RTC_ALRMXR_DATE;
/* 24-hour format */
alrmar &= ~STM32_RTC_ALRMXR_PM;
alrmar |= (tm->tm_hour << STM32_RTC_ALRMXR_HOUR_SHIFT) &
STM32_RTC_ALRMXR_HOUR;
alrmar |= (tm->tm_min << STM32_RTC_ALRMXR_MIN_SHIFT) &
STM32_RTC_ALRMXR_MIN;
alrmar |= (tm->tm_sec << STM32_RTC_ALRMXR_SEC_SHIFT) &
STM32_RTC_ALRMXR_SEC;
stm32_rtc_wpr_unlock(rtc);
/* Disable Alarm */
cr = readl_relaxed(rtc->base + regs->cr);
cr &= ~STM32_RTC_CR_ALRAE;
writel_relaxed(cr, rtc->base + regs->cr);
/*
* Poll Alarm write flag to be sure that Alarm update is allowed: it
* takes around 2 rtc_ck clock cycles
*/
ret = readl_relaxed_poll_timeout_atomic(rtc->base + regs->isr,
isr,
(isr & STM32_RTC_ISR_ALRAWF),
10, 100000);
if (ret) {
dev_err(dev, "Alarm update not allowed\n");
goto end;
}
/* Write to Alarm register */
writel_relaxed(alrmar, rtc->base + regs->alrmar);
if (alrm->enabled)
stm32_rtc_alarm_irq_enable(dev, 1);
else
stm32_rtc_alarm_irq_enable(dev, 0);
end:
stm32_rtc_wpr_lock(rtc);
return ret;
}
static const struct rtc_class_ops stm32_rtc_ops = {
.read_time = stm32_rtc_read_time,
.set_time = stm32_rtc_set_time,
.read_alarm = stm32_rtc_read_alarm,
.set_alarm = stm32_rtc_set_alarm,
.alarm_irq_enable = stm32_rtc_alarm_irq_enable,
};
static void stm32_rtc_clear_events(struct stm32_rtc *rtc,
unsigned int flags)
{
const struct stm32_rtc_registers *regs = &rtc->data->regs;
/* Flags are cleared by writing 0 in RTC_ISR */
writel_relaxed(readl_relaxed(rtc->base + regs->isr) & ~flags,
rtc->base + regs->isr);
}
static const struct stm32_rtc_data stm32_rtc_data = {
.has_pclk = false,
.need_dbp = true,
.has_wakeirq = false,
.regs = {
.tr = 0x00,
.dr = 0x04,
.cr = 0x08,
.isr = 0x0C,
.prer = 0x10,
.alrmar = 0x1C,
.wpr = 0x24,
.sr = 0x0C, /* set to ISR offset to ease alarm management */
.scr = UNDEF_REG,
.verr = UNDEF_REG,
},
.events = {
.alra = STM32_RTC_ISR_ALRAF,
},
.clear_events = stm32_rtc_clear_events,
};
static const struct stm32_rtc_data stm32h7_rtc_data = {
.has_pclk = true,
.need_dbp = true,
.has_wakeirq = false,
.regs = {
.tr = 0x00,
.dr = 0x04,
.cr = 0x08,
.isr = 0x0C,
.prer = 0x10,
.alrmar = 0x1C,
.wpr = 0x24,
.sr = 0x0C, /* set to ISR offset to ease alarm management */
.scr = UNDEF_REG,
.verr = UNDEF_REG,
},
.events = {
.alra = STM32_RTC_ISR_ALRAF,
},
.clear_events = stm32_rtc_clear_events,
};
static void stm32mp1_rtc_clear_events(struct stm32_rtc *rtc,
unsigned int flags)
{
struct stm32_rtc_registers regs = rtc->data->regs;
/* Flags are cleared by writing 1 in RTC_SCR */
writel_relaxed(flags, rtc->base + regs.scr);
}
static const struct stm32_rtc_data stm32mp1_data = {
.has_pclk = true,
.need_dbp = false,
.has_wakeirq = true,
.regs = {
.tr = 0x00,
.dr = 0x04,
.cr = 0x18,
.isr = 0x0C, /* named RTC_ICSR on stm32mp1 */
.prer = 0x10,
.alrmar = 0x40,
.wpr = 0x24,
.sr = 0x50,
.scr = 0x5C,
.verr = 0x3F4,
},
.events = {
.alra = STM32_RTC_SR_ALRA,
},
.clear_events = stm32mp1_rtc_clear_events,
};
static const struct of_device_id stm32_rtc_of_match[] = {
{ .compatible = "st,stm32-rtc", .data = &stm32_rtc_data },
{ .compatible = "st,stm32h7-rtc", .data = &stm32h7_rtc_data },
{ .compatible = "st,stm32mp1-rtc", .data = &stm32mp1_data },
{}
};
MODULE_DEVICE_TABLE(of, stm32_rtc_of_match);
static int stm32_rtc_init(struct platform_device *pdev,
struct stm32_rtc *rtc)
{
const struct stm32_rtc_registers *regs = &rtc->data->regs;
unsigned int prer, pred_a, pred_s, pred_a_max, pred_s_max, cr;
unsigned int rate;
int ret = 0;
rate = clk_get_rate(rtc->rtc_ck);
/* Find prediv_a and prediv_s to obtain the 1Hz calendar clock */
pred_a_max = STM32_RTC_PRER_PRED_A >> STM32_RTC_PRER_PRED_A_SHIFT;
pred_s_max = STM32_RTC_PRER_PRED_S >> STM32_RTC_PRER_PRED_S_SHIFT;
for (pred_a = pred_a_max; pred_a + 1 > 0; pred_a--) {
pred_s = (rate / (pred_a + 1)) - 1;
if (((pred_s + 1) * (pred_a + 1)) == rate)
break;
}
/*
* Can't find a 1Hz, so give priority to RTC power consumption
* by choosing the higher possible value for prediv_a
*/
if ((pred_s > pred_s_max) || (pred_a > pred_a_max)) {
pred_a = pred_a_max;
pred_s = (rate / (pred_a + 1)) - 1;
dev_warn(&pdev->dev, "rtc_ck is %s\n",
(rate < ((pred_a + 1) * (pred_s + 1))) ?
"fast" : "slow");
}
stm32_rtc_wpr_unlock(rtc);
ret = stm32_rtc_enter_init_mode(rtc);
if (ret) {
dev_err(&pdev->dev,
"Can't enter in init mode. Prescaler config failed.\n");
goto end;
}
prer = (pred_s << STM32_RTC_PRER_PRED_S_SHIFT) & STM32_RTC_PRER_PRED_S;
writel_relaxed(prer, rtc->base + regs->prer);
prer |= (pred_a << STM32_RTC_PRER_PRED_A_SHIFT) & STM32_RTC_PRER_PRED_A;
writel_relaxed(prer, rtc->base + regs->prer);
/* Force 24h time format */
cr = readl_relaxed(rtc->base + regs->cr);
cr &= ~STM32_RTC_CR_FMT;
writel_relaxed(cr, rtc->base + regs->cr);
stm32_rtc_exit_init_mode(rtc);
ret = stm32_rtc_wait_sync(rtc);
end:
stm32_rtc_wpr_lock(rtc);
return ret;
}
static int stm32_rtc_probe(struct platform_device *pdev)
{
struct stm32_rtc *rtc;
const struct stm32_rtc_registers *regs;
struct resource *res;
int ret;
rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
if (!rtc)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
rtc->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(rtc->base))
return PTR_ERR(rtc->base);
rtc->data = (struct stm32_rtc_data *)
of_device_get_match_data(&pdev->dev);
regs = &rtc->data->regs;
if (rtc->data->need_dbp) {
rtc->dbp = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
"st,syscfg");
if (IS_ERR(rtc->dbp)) {
dev_err(&pdev->dev, "no st,syscfg\n");
return PTR_ERR(rtc->dbp);
}
ret = of_property_read_u32_index(pdev->dev.of_node, "st,syscfg",
1, &rtc->dbp_reg);
if (ret) {
dev_err(&pdev->dev, "can't read DBP register offset\n");
return ret;
}
ret = of_property_read_u32_index(pdev->dev.of_node, "st,syscfg",
2, &rtc->dbp_mask);
if (ret) {
dev_err(&pdev->dev, "can't read DBP register mask\n");
return ret;
}
}
if (!rtc->data->has_pclk) {
rtc->pclk = NULL;
rtc->rtc_ck = devm_clk_get(&pdev->dev, NULL);
} else {
rtc->pclk = devm_clk_get(&pdev->dev, "pclk");
if (IS_ERR(rtc->pclk)) {
dev_err(&pdev->dev, "no pclk clock");
return PTR_ERR(rtc->pclk);
}
rtc->rtc_ck = devm_clk_get(&pdev->dev, "rtc_ck");
}
if (IS_ERR(rtc->rtc_ck)) {
dev_err(&pdev->dev, "no rtc_ck clock");
return PTR_ERR(rtc->rtc_ck);
}
if (rtc->data->has_pclk) {
ret = clk_prepare_enable(rtc->pclk);
if (ret)
return ret;
}
ret = clk_prepare_enable(rtc->rtc_ck);
if (ret)
goto err;
if (rtc->data->need_dbp)
regmap_update_bits(rtc->dbp, rtc->dbp_reg,
rtc->dbp_mask, rtc->dbp_mask);
/*
* After a system reset, RTC_ISR.INITS flag can be read to check if
* the calendar has been initialized or not. INITS flag is reset by a
* power-on reset (no vbat, no power-supply). It is not reset if
* rtc_ck parent clock has changed (so RTC prescalers need to be
* changed). That's why we cannot rely on this flag to know if RTC
* init has to be done.
*/
ret = stm32_rtc_init(pdev, rtc);
if (ret)
goto err;
rtc->irq_alarm = platform_get_irq(pdev, 0);
if (rtc->irq_alarm <= 0) {
dev_err(&pdev->dev, "no alarm irq\n");
ret = rtc->irq_alarm;
goto err;
}
ret = device_init_wakeup(&pdev->dev, true);
if (rtc->data->has_wakeirq) {
rtc->wakeirq_alarm = platform_get_irq(pdev, 1);
if (rtc->wakeirq_alarm > 0) {
ret = dev_pm_set_dedicated_wake_irq(&pdev->dev,
rtc->wakeirq_alarm);
} else {
ret = rtc->wakeirq_alarm;
if (rtc->wakeirq_alarm == -EPROBE_DEFER)
goto err;
}
}
if (ret)
dev_warn(&pdev->dev, "alarm can't wake up the system: %d", ret);
platform_set_drvdata(pdev, rtc);
rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, pdev->name,
&stm32_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc->rtc_dev)) {
ret = PTR_ERR(rtc->rtc_dev);
dev_err(&pdev->dev, "rtc device registration failed, err=%d\n",
ret);
goto err;
}
/* Handle RTC alarm interrupts */
ret = devm_request_threaded_irq(&pdev->dev, rtc->irq_alarm, NULL,
stm32_rtc_alarm_irq, IRQF_ONESHOT,
pdev->name, rtc);
if (ret) {
dev_err(&pdev->dev, "IRQ%d (alarm interrupt) already claimed\n",
rtc->irq_alarm);
goto err;
}
/*
* If INITS flag is reset (calendar year field set to 0x00), calendar
* must be initialized
*/
if (!(readl_relaxed(rtc->base + regs->isr) & STM32_RTC_ISR_INITS))
dev_warn(&pdev->dev, "Date/Time must be initialized\n");
if (regs->verr != UNDEF_REG) {
u32 ver = readl_relaxed(rtc->base + regs->verr);
dev_info(&pdev->dev, "registered rev:%d.%d\n",
(ver >> STM32_RTC_VERR_MAJREV_SHIFT) & 0xF,
(ver >> STM32_RTC_VERR_MINREV_SHIFT) & 0xF);
}
return 0;
err:
if (rtc->data->has_pclk)
clk_disable_unprepare(rtc->pclk);
clk_disable_unprepare(rtc->rtc_ck);
if (rtc->data->need_dbp)
regmap_update_bits(rtc->dbp, rtc->dbp_reg, rtc->dbp_mask, 0);
dev_pm_clear_wake_irq(&pdev->dev);
device_init_wakeup(&pdev->dev, false);
return ret;
}
static int stm32_rtc_remove(struct platform_device *pdev)
{
struct stm32_rtc *rtc = platform_get_drvdata(pdev);
const struct stm32_rtc_registers *regs = &rtc->data->regs;
unsigned int cr;
/* Disable interrupts */
stm32_rtc_wpr_unlock(rtc);
cr = readl_relaxed(rtc->base + regs->cr);
cr &= ~STM32_RTC_CR_ALRAIE;
writel_relaxed(cr, rtc->base + regs->cr);
stm32_rtc_wpr_lock(rtc);
clk_disable_unprepare(rtc->rtc_ck);
if (rtc->data->has_pclk)
clk_disable_unprepare(rtc->pclk);
/* Enable backup domain write protection if needed */
if (rtc->data->need_dbp)
regmap_update_bits(rtc->dbp, rtc->dbp_reg, rtc->dbp_mask, 0);
dev_pm_clear_wake_irq(&pdev->dev);
device_init_wakeup(&pdev->dev, false);
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int stm32_rtc_suspend(struct device *dev)
{
struct stm32_rtc *rtc = dev_get_drvdata(dev);
if (rtc->data->has_pclk)
clk_disable_unprepare(rtc->pclk);
if (device_may_wakeup(dev))
return enable_irq_wake(rtc->irq_alarm);
return 0;
}
static int stm32_rtc_resume(struct device *dev)
{
struct stm32_rtc *rtc = dev_get_drvdata(dev);
int ret = 0;
if (rtc->data->has_pclk) {
ret = clk_prepare_enable(rtc->pclk);
if (ret)
return ret;
}
ret = stm32_rtc_wait_sync(rtc);
if (ret < 0)
return ret;
if (device_may_wakeup(dev))
return disable_irq_wake(rtc->irq_alarm);
return ret;
}
#endif
static SIMPLE_DEV_PM_OPS(stm32_rtc_pm_ops,
stm32_rtc_suspend, stm32_rtc_resume);
static struct platform_driver stm32_rtc_driver = {
.probe = stm32_rtc_probe,
.remove = stm32_rtc_remove,
.driver = {
.name = DRIVER_NAME,
.pm = &stm32_rtc_pm_ops,
.of_match_table = stm32_rtc_of_match,
},
};
module_platform_driver(stm32_rtc_driver);
MODULE_ALIAS("platform:" DRIVER_NAME);
MODULE_AUTHOR("Amelie Delaunay <amelie.delaunay@st.com>");
MODULE_DESCRIPTION("STMicroelectronics STM32 Real Time Clock driver");
MODULE_LICENSE("GPL v2");
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