pwm: stm32: Refuse too small period requests

commit c45fcf46ca2368dafe7e5c513a711a6f0f974308 upstream.

If period_ns is small, prd might well become 0. Catch that case because
otherwise with

	regmap_write(priv->regmap, TIM_ARR, prd - 1);

a few lines down quite a big period is configured.

Fixes: 7edf7369205b ("pwm: Add driver for STM32 plaftorm")
Cc: stable@vger.kernel.org
Reviewed-by: Trevor Gamblin <tgamblin@baylibre.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/b86f62f099983646f97eeb6bfc0117bb2d0c340d.1718979150.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c
index dd2ee5d9ca066a94bcb07525fe52952a5b4df397..9bdab6c24fbafa8b5e8fdffd98b3273d270797ce 100644 (file)
--- a/drivers/pwm/pwm-stm32.c
+++ b/drivers/pwm/pwm-stm32.c
@@ -344,6 +344,9 @@ static int stm32_pwm_config(struct stm32_pwm *priv, int ch,
 
        prd = div;
 
+       if (!prd)
+               return -EINVAL;
+
        if (prescaler > MAX_TIM_PSC)
                return -EINVAL;