linux-kernel - [PATCH v2] counter: stm32-timer-cnt: Reset TIM

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Date:   Thu, 13 Apr 2023 23:23:39 +0200
From:   Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
To:     Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        William Breathitt Gray <william.gray@...aro.org>,
        Fabrice Gasnier <fabrice.gasnier@...s.st.com>
Cc:     Olivier Moysan <olivier.moysan@...s.st.com>,
        linux-iio@...r.kernel.org, Lee Jones <lee@...nel.org>,
        linux-kernel@...r.kernel.org,
        Thierry Reding <thierry.reding@...il.com>,
        kernel@...gutronix.de, linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH v2] counter: stm32-timer-cnt: Reset TIM_TISEL to its default value in probe

The driver assumes that the input selection register (TIM_TISEL) is at
its reset default value. Usually this is the case, but the bootloader
might have modified it.

This bases on a similar patch submitted by Olivier Moysan for pwm-stm32.

Reviewed-by: Fabrice Gasnier <fabrice.gasnier@...s.st.com
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
---
Changes since (implicit) v1 sent with Message-Id:
20230412153709.3557323-1-u.kleine-koenig@...gutronix.de .

 - Only reset TIM_TISEL as suggested by Fabrice
 - Add Fabrice's Review tag

 drivers/counter/stm32-timer-cnt.c | 3 +++
 include/linux/mfd/stm32-timers.h  | 1 +
 2 files changed, 4 insertions(+)

diff --git a/drivers/counter/stm32-timer-cnt.c b/drivers/counter/stm32-timer-cnt.c
index 9bf20a5d6bda..6206d2dc3d47 100644
--- a/drivers/counter/stm32-timer-cnt.c
+++ b/drivers/counter/stm32-timer-cnt.c
@@ -342,6 +342,9 @@ static int stm32_timer_cnt_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, priv);
 
+	/* Reset input selector to its default input */
+	regmap_write(priv->regmap, TIM_TISEL, 0x0);
+
 	/* Register Counter device */
 	ret = devm_counter_add(dev, counter);
 	if (ret < 0)
diff --git a/include/linux/mfd/stm32-timers.h b/include/linux/mfd/stm32-timers.h
index 5f5c43fd69dd..1b94325febb3 100644
--- a/include/linux/mfd/stm32-timers.h
+++ b/include/linux/mfd/stm32-timers.h
@@ -31,6 +31,7 @@
 #define TIM_BDTR	0x44	/* Break and Dead-Time Reg */
 #define TIM_DCR		0x48	/* DMA control register    */
 #define TIM_DMAR	0x4C	/* DMA register for transfer */
+#define TIM_TISEL	0x68	/* Input Selection         */
 
 #define TIM_CR1_CEN	BIT(0)	/* Counter Enable	   */
 #define TIM_CR1_DIR	BIT(4)  /* Counter Direction	   */

base-commit: fe15c26ee26efa11741a7b632e9f23b01aca4cc6
-- 
2.39.2