[PATCH] clk: stm32: add support for reset_control_reset()

[Gabriel Fernandez]

The STM32 RCC reset controller currently implements only .assert(),
.deassert(), and .status().
As a result, reset_control_reset() returns -ENOTSUPP, forcing consumers
to open-code the assert / delay / deassert sequence.

Implement .reset() to provide the standard reset operation and avoid
duplicating this logic in consumers.

Signed-off-by: Gabriel Fernandez <gabriel.fernandez at foss.st.com>
---
 drivers/clk/stm32/reset-stm32.c | 45 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/drivers/clk/stm32/reset-stm32.c b/drivers/clk/stm32/reset-stm32.c
index fc237fccae68..9b853417e9c5 100644
--- a/drivers/clk/stm32/reset-stm32.c
+++ b/drivers/clk/stm32/reset-stm32.c
@@ -4,6 +4,8 @@
  * Author: Gabriel Fernandez <gabriel.fernandez at foss.st.com> for STMicroelectronics.
  */
 
+#include <linux/delay.h>
+#include <linux/iopoll.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
@@ -13,6 +15,13 @@
 
 #include "reset-stm32.h"
 
+/* Hold time between reset assertion and deassertion */
+#define STM32_RESET_ASSERT_DELAY_US		2
+
+/* Polling of the reset status bit after deassertion */
+#define STM32_RESET_DEASSERT_POLL_US		10
+#define STM32_RESET_DEASSERT_TIMEOUT_US		(10 * USEC_PER_MSEC)
+
 struct stm32_reset_data {
 	/* reset lock */
 	spinlock_t			lock;
@@ -119,9 +128,45 @@ static int stm32_reset_status(struct reset_controller_dev *rcdev,
 	return !!(reg & BIT(ptr_line->bit_idx));
 }
 
+static int stm32_check_deassert(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	struct stm32_reset_data *data = to_stm32_reset_data(rcdev);
+	struct stm32_reset_cfg line_reset;
+	const struct stm32_reset_cfg *ptr_line;
+	u32 reg;
+
+	ptr_line = stm32_get_reset_line(rcdev, id, &line_reset);
+	if (!ptr_line)
+		return -EPERM;
+
+	return readl_poll_timeout(data->membase + ptr_line->offset, reg,
+				  !(reg & BIT(ptr_line->bit_idx)),
+				  STM32_RESET_DEASSERT_POLL_US,
+				  STM32_RESET_DEASSERT_TIMEOUT_US);
+}
+
+static int stm32_reset(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	int ret;
+
+	ret = stm32_reset_assert(rcdev, id);
+	if (ret)
+		return ret;
+
+	fsleep(STM32_RESET_ASSERT_DELAY_US);
+
+	ret = stm32_reset_deassert(rcdev, id);
+	if (ret)
+		return ret;
+
+	return stm32_check_deassert(rcdev, id);
+}
+
 static const struct reset_control_ops stm32_reset_ops = {
 	.assert		= stm32_reset_assert,
 	.deassert	= stm32_reset_deassert,
+	.reset		= stm32_reset,
 	.status		= stm32_reset_status,
 };
 

---
base-commit: a90ee4305c4a5df72c11b31dacfdc76e00fcf78a
change-id: 20261013-ups_reset_control_reset-4c2f1b08ddf1

Best regards,
-- 
Gabriel Fernandez <gabriel.fernandez at foss.st.com>