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Subject[PATCHv2 2/2] rtc: stm32: add STM32H7 RTC support
Date
This patch adds support for STM32H7 RTC. On STM32H7, the RTC bus interface
clock (APB clock) needs to be enabled.

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
---
drivers/rtc/rtc-stm32.c | 82 +++++++++++++++++++++++++++++++++++++++----------
1 file changed, 65 insertions(+), 17 deletions(-)

diff --git a/drivers/rtc/rtc-stm32.c b/drivers/rtc/rtc-stm32.c
index bd57eb1..3a5c3d7 100644
--- a/drivers/rtc/rtc-stm32.c
+++ b/drivers/rtc/rtc-stm32.c
@@ -94,11 +94,17 @@
/* STM32_PWR_CR bit field */
#define PWR_CR_DBP BIT(8)

+struct stm32_rtc_data {
+ bool has_pclk;
+};
+
struct stm32_rtc {
struct rtc_device *rtc_dev;
void __iomem *base;
struct regmap *dbp;
- struct clk *ck_rtc;
+ struct stm32_rtc_data *data;
+ struct clk *pclk;
+ struct clk *rtc_ck;
int irq_alarm;
};

@@ -122,9 +128,9 @@ static int stm32_rtc_enter_init_mode(struct stm32_rtc *rtc)
writel_relaxed(isr, rtc->base + STM32_RTC_ISR);

/*
- * It takes around 2 ck_rtc clock cycles to enter in
+ * It takes around 2 rtc_ck 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
+ * 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(
@@ -153,7 +159,7 @@ static int stm32_rtc_wait_sync(struct stm32_rtc *rtc)

/*
* Wait for RSF to be set to ensure the calendar registers are
- * synchronised, it takes around 2 ck_rtc clock cycles
+ * synchronised, it takes around 2 rtc_ck clock cycles
*/
return readl_relaxed_poll_timeout_atomic(rtc->base + STM32_RTC_ISR,
isr,
@@ -456,7 +462,7 @@ static int stm32_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)

/*
* Poll Alarm write flag to be sure that Alarm update is allowed: it
- * takes around 2 ck_rtc clock cycles
+ * takes around 2 rtc_ck clock cycles
*/
ret = readl_relaxed_poll_timeout_atomic(rtc->base + STM32_RTC_ISR,
isr,
@@ -490,8 +496,17 @@ static int stm32_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
.alarm_irq_enable = stm32_rtc_alarm_irq_enable,
};

+static const struct stm32_rtc_data stm32_rtc_data = {
+ .has_pclk = false,
+};
+
+static const struct stm32_rtc_data stm32h7_rtc_data = {
+ .has_pclk = true,
+};
+
static const struct of_device_id stm32_rtc_of_match[] = {
- { .compatible = "st,stm32-rtc" },
+ { .compatible = "st,stm32-rtc", .data = &stm32_rtc_data },
+ { .compatible = "st,stm32h7-rtc", .data = &stm32h7_rtc_data },
{}
};
MODULE_DEVICE_TABLE(of, stm32_rtc_of_match);
@@ -503,7 +518,7 @@ static int stm32_rtc_init(struct platform_device *pdev,
unsigned int rate;
int ret = 0;

- rate = clk_get_rate(rtc->ck_rtc);
+ 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;
@@ -524,7 +539,7 @@ static int stm32_rtc_init(struct platform_device *pdev,
pred_a = pred_a_max;
pred_s = (rate / (pred_a + 1)) - 1;

- dev_warn(&pdev->dev, "ck_rtc is %s\n",
+ dev_warn(&pdev->dev, "rtc_ck is %s\n",
(rate < ((pred_a + 1) * (pred_s + 1))) ?
"fast" : "slow");
}
@@ -561,6 +576,7 @@ static int stm32_rtc_probe(struct platform_device *pdev)
{
struct stm32_rtc *rtc;
struct resource *res;
+ const struct of_device_id *match;
int ret;

rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
@@ -579,15 +595,34 @@ static int stm32_rtc_probe(struct platform_device *pdev)
return PTR_ERR(rtc->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);
+ match = of_match_device(stm32_rtc_of_match, &pdev->dev);
+ rtc->data = (struct stm32_rtc_data *)match->data;
+
+ 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->ck_rtc);
+ ret = clk_prepare_enable(rtc->rtc_ck);
if (ret)
- return ret;
+ goto err;

regmap_update_bits(rtc->dbp, PWR_CR, PWR_CR_DBP, PWR_CR_DBP);

@@ -595,7 +630,7 @@ static int stm32_rtc_probe(struct platform_device *pdev)
* 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
+ * 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.
*/
@@ -646,7 +681,9 @@ static int stm32_rtc_probe(struct platform_device *pdev)

return 0;
err:
- clk_disable_unprepare(rtc->ck_rtc);
+ if (rtc->data->has_pclk)
+ clk_disable_unprepare(rtc->pclk);
+ clk_disable_unprepare(rtc->rtc_ck);

regmap_update_bits(rtc->dbp, PWR_CR, PWR_CR_DBP, 0);

@@ -667,7 +704,9 @@ static int stm32_rtc_remove(struct platform_device *pdev)
writel_relaxed(cr, rtc->base + STM32_RTC_CR);
stm32_rtc_wpr_lock(rtc);

- clk_disable_unprepare(rtc->ck_rtc);
+ clk_disable_unprepare(rtc->rtc_ck);
+ if (rtc->data->has_pclk)
+ clk_disable_unprepare(rtc->pclk);

/* Enable backup domain write protection */
regmap_update_bits(rtc->dbp, PWR_CR, PWR_CR_DBP, 0);
@@ -682,6 +721,9 @@ 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);

@@ -693,6 +735,12 @@ 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;
--
1.9.1
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