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Subject[PATCHv4 3/8] rtc: add STM32 RTC driver
Date
This patch adds support for the STM32 RTC.

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
---
drivers/rtc/Kconfig | 11 +
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-stm32.c | 727 ++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 739 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..f49226e
--- /dev/null
+++ b/drivers/rtc/rtc-stm32.c
@@ -0,0 +1,727 @@
+/*
+ * Copyright (C) Amelie Delaunay 2016
+ * Author: Amelie Delaunay <amelie.delaunay@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>
+
+#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;
+ 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;
+
+ /* Time and Date in BCD format */
+ tr = readl_relaxed(rtc->base + STM32_RTC_TR);
+ dr = readl_relaxed(rtc->base + STM32_RTC_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);
+ 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 + 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);
+
+ 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;
+
+ alrmar = readl_relaxed(rtc->base + STM32_RTC_ALRMAR);
+ cr = readl_relaxed(rtc->base + STM32_RTC_CR);
+ isr = readl_relaxed(rtc->base + STM32_RTC_ISR);
+
+ 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 int isr, cr;
+
+ 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 flag, 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);
+
+ 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 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 + 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;
+ }
+
+ /* 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);
+
+ 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;
+ 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");
+ }
+
+ 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);
+
+ 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);
+ }
+
+ 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 = rtc->irq_alarm;
+ 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.delaunay@st.com>");
+MODULE_DESCRIPTION("STMicroelectronics STM32 Real Time Clock driver");
+MODULE_LICENSE("GPL v2");
--
1.9.1
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  Last update: 2017-01-11 13:50    [W:0.048 / U:0.448 seconds]
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