On Fri, Dec 16, 2016 at 09:50:52AM +0100, Amelie Delaunay wrote:
> This patch adds support for the STM32 RTC.
>
> Signed-off-by: Amelie Delaunay <amelie.delau...@st.com>
> ---
> drivers/rtc/Kconfig | 11 +
> drivers/rtc/Makefile | 1 +
> drivers/rtc/rtc-stm32.c | 776
> ++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 788 insertions(+)
> create mode 100644 drivers/rtc/rtc-stm32.c
>
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index e859d14..11eb28a 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -1706,6 +1706,17 @@ config RTC_DRV_PIC32
> This driver can also be built as a module. If so, the module
> will be called rtc-pic32
>
> +config RTC_DRV_STM32
> + tristate "STM32 RTC"
> + select REGMAP_MMIO
> + depends on ARCH_STM32 || COMPILE_TEST
> + help
> + If you say yes here you get support for the STM32 On-Chip
> + Real Time Clock.
> +
> + This driver can also be built as a module, if so, the module
> + will be called "rtc-stm32".
> +
> comment "HID Sensor RTC drivers"
>
> config RTC_DRV_HID_SENSOR_TIME
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 1ac694a..87bd9cc 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -144,6 +144,7 @@ obj-$(CONFIG_RTC_DRV_SNVS) += rtc-snvs.o
> obj-$(CONFIG_RTC_DRV_SPEAR) += rtc-spear.o
> obj-$(CONFIG_RTC_DRV_STARFIRE) += rtc-starfire.o
> obj-$(CONFIG_RTC_DRV_STK17TA8) += rtc-stk17ta8.o
> +obj-$(CONFIG_RTC_DRV_STM32) += rtc-stm32.o
> obj-$(CONFIG_RTC_DRV_STMP) += rtc-stmp3xxx.o
> obj-$(CONFIG_RTC_DRV_ST_LPC) += rtc-st-lpc.o
> obj-$(CONFIG_RTC_DRV_SUN4V) += rtc-sun4v.o
> diff --git a/drivers/rtc/rtc-stm32.c b/drivers/rtc/rtc-stm32.c
> new file mode 100644
> index 0000000..6ce0f5a
> --- /dev/null
> +++ b/drivers/rtc/rtc-stm32.c
> @@ -0,0 +1,776 @@
> +/*
> + * Copyright (C) Amelie Delaunay 2016
> + * Author: Amelie Delaunay <amelie.delau...@st.com>
> + * License terms: GNU General Public License (GPL), version 2
> + */
> +
> +#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/regmap.h>
> +#include <linux/rtc.h>
> +#include <linux/spinlock.h>
> +
> +#define DRIVER_NAME "stm32_rtc"
> +
> +/* STM32 RTC registers */
> +#define STM32_RTC_TR 0x00
> +#define STM32_RTC_DR 0x04
> +#define STM32_RTC_CR 0x08
> +#define STM32_RTC_ISR 0x0C
> +#define STM32_RTC_PRER 0x10
> +#define STM32_RTC_ALRMAR 0x1C
> +#define STM32_RTC_WPR 0x24
> +
> +/* 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 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_WPR key constants */
> +#define RTC_WPR_1ST_KEY 0xCA
> +#define RTC_WPR_2ND_KEY 0x53
> +#define RTC_WPR_WRONG_KEY 0xFF
> +
> +/*
> + * RTC registers are protected agains parasitic write access.
> + * PWR_CR_DBP bit must be set to enable write access to RTC registers.
> + */
> +/* STM32_PWR_CR */
> +#define PWR_CR 0x00
> +/* STM32_PWR_CR bit field */
> +#define PWR_CR_DBP BIT(8)
> +
> +static struct regmap *dbp;
> +
> +struct stm32_rtc {
> + struct rtc_device *rtc_dev;
> + void __iomem *base;
> + struct clk *ck_rtc;
> + spinlock_t lock; /* Protects registers accesses */
> + int irq_alarm;
> +};
> +
> +static void stm32_rtc_wpr_unlock(struct stm32_rtc *rtc)
> +{
> + writel_relaxed(RTC_WPR_1ST_KEY, rtc->base + STM32_RTC_WPR);
> + writel_relaxed(RTC_WPR_2ND_KEY, rtc->base + STM32_RTC_WPR);
> +}
> +
> +static void stm32_rtc_wpr_lock(struct stm32_rtc *rtc)
> +{
> + writel_relaxed(RTC_WPR_WRONG_KEY, rtc->base + STM32_RTC_WPR);
> +}
> +
> +static int stm32_rtc_enter_init_mode(struct stm32_rtc *rtc)
> +{
> + unsigned int isr = readl_relaxed(rtc->base + STM32_RTC_ISR);
> +
> + if (!(isr & STM32_RTC_ISR_INITF)) {
> + isr |= STM32_RTC_ISR_INIT;
> + writel_relaxed(isr, rtc->base + STM32_RTC_ISR);
> +
> + /*
> + * It takes around 2 ck_rtc clock cycles to enter in
> + * initialization phase mode (and have INITF flag set). As
> + * slowest ck_rtc 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 + STM32_RTC_ISR,
> + isr, (isr & STM32_RTC_ISR_INITF),
> + 10, 100000);
> + }
> +
> + return 0;
> +}
> +
> +static void stm32_rtc_exit_init_mode(struct stm32_rtc *rtc)
> +{
> + unsigned int isr = readl_relaxed(rtc->base + STM32_RTC_ISR);
> +
> + isr &= ~STM32_RTC_ISR_INIT;
> + writel_relaxed(isr, rtc->base + STM32_RTC_ISR);
> +}
> +
> +static int stm32_rtc_wait_sync(struct stm32_rtc *rtc)
> +{
> + unsigned int isr = readl_relaxed(rtc->base + STM32_RTC_ISR);
> +
> + isr &= ~STM32_RTC_ISR_RSF;
> + writel_relaxed(isr, rtc->base + STM32_RTC_ISR);
> +
> + /*
> + * Wait for RSF to be set to ensure the calendar registers are
> + * synchronised, it takes around 2 ck_rtc clock cycles
> + */
> + return readl_relaxed_poll_timeout_atomic(rtc->base + STM32_RTC_ISR,
> + isr,
> + (isr & STM32_RTC_ISR_RSF),
> + 10, 100000);
> +}
> +
> +static irqreturn_t stm32_rtc_alarm_irq(int irq, void *dev_id)
> +{
> + struct stm32_rtc *rtc = (struct stm32_rtc *)dev_id;
> + unsigned int isr, cr;
> +
> + mutex_lock(&rtc->rtc_dev->ops_lock);
> +
> + isr = readl_relaxed(rtc->base + STM32_RTC_ISR);
> + cr = readl_relaxed(rtc->base + STM32_RTC_CR);
> +
> + if ((isr & STM32_RTC_ISR_ALRAF) &&
> + (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 flag, otherwise new events won't be received */
> + writel_relaxed(isr & ~STM32_RTC_ISR_ALRAF,
> + rtc->base + STM32_RTC_ISR);
> + }
> +
> + 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);
> + unsigned int tr, dr;
> + unsigned long irqflags;
> +
> + spin_lock_irqsave(&rtc->lock, irqflags);
> +
> + /* Time and Date in BCD format */
> + tr = readl_relaxed(rtc->base + STM32_RTC_TR);
> + dr = readl_relaxed(rtc->base + STM32_RTC_DR);
> +
> + spin_unlock_irqrestore(&rtc->lock, irqflags);
> +
> + 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);
> +
> + if (rtc_valid_tm(tm) < 0) {
> + dev_err(dev, "%s: rtc_time is not valid.\n", __func__);
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +static int stm32_rtc_set_time(struct device *dev, struct rtc_time *tm)
> +{
> + struct stm32_rtc *rtc = dev_get_drvdata(dev);
> + unsigned int tr, dr;
> + unsigned long irqflags;
> + int ret = 0;
> +
> + if (rtc_valid_tm(tm) < 0) {
> + dev_err(dev, "%s: rtc_time is not valid.\n", __func__);
> + return -EINVAL;
> + }
> +
> + 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);
> +
> + spin_lock_irqsave(&rtc->lock, irqflags);
> +
> + 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 + STM32_RTC_TR);
> + writel_relaxed(dr, rtc->base + STM32_RTC_DR);
> +
> + stm32_rtc_exit_init_mode(rtc);
> +
> + ret = stm32_rtc_wait_sync(rtc);
> +end:
> + stm32_rtc_wpr_lock(rtc);
> +
> + spin_unlock_irqrestore(&rtc->lock, irqflags);
> +
> + return ret;
> +}
> +
> +static int stm32_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> + struct stm32_rtc *rtc = dev_get_drvdata(dev);
> + struct rtc_time *tm = &alrm->time;
> + unsigned int alrmar, cr, isr;
> + unsigned long irqflags;
> +
> + spin_lock_irqsave(&rtc->lock, irqflags);
> +
> + alrmar = readl_relaxed(rtc->base + STM32_RTC_ALRMAR);
> + cr = readl_relaxed(rtc->base + STM32_RTC_CR);
> + isr = readl_relaxed(rtc->base + STM32_RTC_ISR);
> +
> + spin_unlock_irqrestore(&rtc->lock, irqflags);
> +
> + 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 = (isr & STM32_RTC_ISR_ALRAF) ? 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);
> + unsigned long irqflags;
> + unsigned int isr, cr;
> +
> + spin_lock_irqsave(&rtc->lock, irqflags);
> +
> + cr = readl_relaxed(rtc->base + STM32_RTC_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 + STM32_RTC_CR);
> +
> + /* Clear event irqflags, otherwise new events won't be received */
> + isr = readl_relaxed(rtc->base + STM32_RTC_ISR);
> + isr &= ~STM32_RTC_ISR_ALRAF;
> + writel_relaxed(isr, rtc->base + STM32_RTC_ISR);
> +
> + stm32_rtc_wpr_lock(rtc);
> +
> + spin_unlock_irqrestore(&rtc->lock, irqflags);
> +
> + return 0;
> +}
> +
> +static int stm32_rtc_valid_alrm(struct stm32_rtc *rtc, struct rtc_time *tm)
> +{
> + unsigned int cur_day, cur_mon, cur_year, cur_hour, cur_min, cur_sec;
> + unsigned int dr = readl_relaxed(rtc->base + STM32_RTC_DR);
> + unsigned int tr = readl_relaxed(rtc->base + STM32_RTC_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);
> + struct rtc_time *tm = &alrm->time;
> + unsigned long irqflags;
> + unsigned int cr, isr, alrmar;
> + int ret = 0;
> +
> + if (rtc_valid_tm(tm)) {
> + dev_err(dev, "Alarm time not valid.\n");
> + return -EINVAL;
> + }
> +
> + 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;
> + }
> +
> + spin_lock_irqsave(&rtc->lock, irqflags);
> +
> + stm32_rtc_wpr_unlock(rtc);
> +
> + /* Disable Alarm */
> + cr = readl_relaxed(rtc->base + STM32_RTC_CR);
> + cr &= ~STM32_RTC_CR_ALRAE;
> + writel_relaxed(cr, rtc->base + STM32_RTC_CR);
> +
> + /*
> + * Poll Alarm write flag to be sure that Alarm update is allowed: it
> + * takes around 2 ck_rtc clock cycles
> + */
> + ret = readl_relaxed_poll_timeout_atomic(rtc->base + STM32_RTC_ISR,
> + isr,
> + (isr & STM32_RTC_ISR_ALRAWF),
> + 10, 100000);
> +
> + if (ret) {
> + dev_err(dev, "Alarm update not allowed\n");
> + goto end;
> + }
> +
> + 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;
All this work on alrmar is done while the spinlock is held. If I'm not
mistaking nothing prevents you from doing that processing before taking the
spinlock.
> +
> + /* Write to Alarm register */
> + writel_relaxed(alrmar, rtc->base + STM32_RTC_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);
> +
> + spin_unlock_irqrestore(&rtc->lock, irqflags);
> +
> + 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,
> +};
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id stm32_rtc_of_match[] = {
> + { .compatible = "st,stm32-rtc" },
> + {}
> +};
> +MODULE_DEVICE_TABLE(of, stm32_rtc_of_match);
> +#endif
> +
> +static int stm32_rtc_init(struct platform_device *pdev,
> + struct stm32_rtc *rtc)
> +{
> + unsigned int prer, pred_a, pred_s, pred_a_max, pred_s_max, cr;
> + unsigned int rate;
> + unsigned long irqflags;
> + int ret = 0;
> +
> + rate = clk_get_rate(rtc->ck_rtc);
> +
> + /* 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 >= 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, "ck_rtc is %s\n",
> + (rate - ((pred_a + 1) * (pred_s + 1)) < 0) ?
> + "fast" : "slow");
> + }
> +
> + spin_lock_irqsave(&rtc->lock, irqflags);
> +
> + 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 + STM32_RTC_PRER);
> + prer |= (pred_a << STM32_RTC_PRER_PRED_A_SHIFT) & STM32_RTC_PRER_PRED_A;
> + writel_relaxed(prer, rtc->base + STM32_RTC_PRER);
> +
> + /* Force 24h time format */
> + cr = readl_relaxed(rtc->base + STM32_RTC_CR);
> + cr &= ~STM32_RTC_CR_FMT;
> + writel_relaxed(cr, rtc->base + STM32_RTC_CR);
> +
> + stm32_rtc_exit_init_mode(rtc);
> +
> + ret = stm32_rtc_wait_sync(rtc);
> +end:
> + stm32_rtc_wpr_lock(rtc);
> +
> + spin_unlock_irqrestore(&rtc->lock, irqflags);
> +
> + return ret;
> +}
> +
> +static int stm32_rtc_probe(struct platform_device *pdev)
> +{
> + struct stm32_rtc *rtc;
> + 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);
> +
> + dbp = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "st,syscfg");
> + if (IS_ERR(dbp)) {
> + dev_err(&pdev->dev, "no st,syscfg\n");
> + return PTR_ERR(dbp);
> + }
> +
> + spin_lock_init(&rtc->lock);
> +
> + rtc->ck_rtc = devm_clk_get(&pdev->dev, NULL);
> + if (IS_ERR(rtc->ck_rtc)) {
> + dev_err(&pdev->dev, "no ck_rtc clock");
> + return PTR_ERR(rtc->ck_rtc);
> + }
> +
> + ret = clk_prepare_enable(rtc->ck_rtc);
> + if (ret)
> + return ret;
> +
> + regmap_update_bits(dbp, PWR_CR, PWR_CR_DBP, PWR_CR_DBP);
> +
> + /*
> + * After a system reset, RTC_ISR.INITS flag can be read to check if
> + * the calendar has been initalized or not. INITS flag is reset by a
> + * power-on reset (no vbat, no power-supply). It is not reset if
> + * ck_rtc 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 = -ENOENT;
Function platform_get_irq() returns a wealth of error codes that are lost here.
Doing 'ret = rtc->irq_alarm;' would prevent that from happening.
> + goto err;
> + }
> +
> + platform_set_drvdata(pdev, rtc);
> +
> + ret = device_init_wakeup(&pdev->dev, true);
> + if (ret)
> + dev_warn(&pdev->dev,
> + "alarm won't be able to wake up the system");
> +
> + 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_TRIGGER_RISING | 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 + STM32_RTC_ISR) & STM32_RTC_ISR_INITS))
> + dev_warn(&pdev->dev, "Date/Time must be initialized\n");
> +
> + return 0;
> +err:
> + clk_disable_unprepare(rtc->ck_rtc);
> +
> + regmap_update_bits(dbp, PWR_CR, PWR_CR_DBP, ~PWR_CR_DBP);
> +
> + device_init_wakeup(&pdev->dev, false);
> +
> + return ret;
> +}
> +
> +static int __exit stm32_rtc_remove(struct platform_device *pdev)
> +{
> + struct stm32_rtc *rtc = platform_get_drvdata(pdev);
> + unsigned int cr;
> +
> + /* Disable interrupts */
> + stm32_rtc_wpr_unlock(rtc);
> + cr = readl_relaxed(rtc->base + STM32_RTC_CR);
> + cr &= ~STM32_RTC_CR_ALRAIE;
> + writel_relaxed(cr, rtc->base + STM32_RTC_CR);
> + stm32_rtc_wpr_lock(rtc);
> +
> + clk_disable_unprepare(rtc->ck_rtc);
> +
> + /* Enable backup domain write protection */
> + regmap_update_bits(dbp, PWR_CR, PWR_CR_DBP, ~PWR_CR_DBP);
> +
> + 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 (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;
> +
> + 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.delau...@st.com>");
> +MODULE_DESCRIPTION("STMicroelectronics STM32 Real Time Clock driver");
> +MODULE_LICENSE("GPL v2");
> --
> 1.9.1
>
