2020-07-17 23:22:59

by Scott Branden

Subject: [PATCH v3] pwm: bcm-iproc: handle clk_get_rate() return

From: Rayagonda Kokatanur <[email protected]>

Handle clk_get_rate() returning 0 to avoid possible division by zero.

Fixes: daa5abc41c80 ("pwm: Add support for Broadcom iProc PWM controller")
Signed-off-by: Rayagonda Kokatanur <[email protected]>
Signed-off-by: Scott Branden <[email protected]>
Reviewed-off-by: Ray Jui <[email protected]>

---
Changes from v2: update commit message to remove <= condition
as clk_get_rate only returns value >= 0
---
drivers/pwm/pwm-bcm-iproc.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/pwm/pwm-bcm-iproc.c b/drivers/pwm/pwm-bcm-iproc.c
index 1f829edd8ee7..d392a828fc49 100644
--- a/drivers/pwm/pwm-bcm-iproc.c
+++ b/drivers/pwm/pwm-bcm-iproc.c
@@ -85,8 +85,6 @@ static void iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
u64 tmp, multi, rate;
u32 value, prescale;

- rate = clk_get_rate(ip->clk);
-
value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);

if (value & BIT(IPROC_PWM_CTRL_EN_SHIFT(pwm->hwpwm)))
@@ -99,6 +97,13 @@ static void iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
else
state->polarity = PWM_POLARITY_INVERSED;

+ rate = clk_get_rate(ip->clk);
+ if (rate == 0) {
+ state->period = 0;
+ state->duty_cycle = 0;
+ return;
+ }
+
value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
prescale = value >> IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm);
prescale &= IPROC_PWM_PRESCALE_MAX;
--
2.17.1

2020-07-17 23:58:43

by Ray Jui

Subject: Re: [PATCH v3] pwm: bcm-iproc: handle clk_get_rate() return

On 7/17/2020 4:19 PM, Scott Branden wrote:
> From: Rayagonda Kokatanur <[email protected]>
>
> Handle clk_get_rate() returning 0 to avoid possible division by zero.
>
> Fixes: daa5abc41c80 ("pwm: Add support for Broadcom iProc PWM controller")
> Signed-off-by: Rayagonda Kokatanur <[email protected]>
> Signed-off-by: Scott Branden <[email protected]>
> Reviewed-off-by: Ray Jui <[email protected]>

Typo. Should be 'Reviewed-by: Ray Jui <[email protected]>', :)

>
> ---
> Changes from v2: update commit message to remove <= condition
> as clk_get_rate only returns value >= 0
> ---
> drivers/pwm/pwm-bcm-iproc.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pwm/pwm-bcm-iproc.c b/drivers/pwm/pwm-bcm-iproc.c
> index 1f829edd8ee7..d392a828fc49 100644
> --- a/drivers/pwm/pwm-bcm-iproc.c
> +++ b/drivers/pwm/pwm-bcm-iproc.c
> @@ -85,8 +85,6 @@ static void iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> u64 tmp, multi, rate;
> u32 value, prescale;
>
> - rate = clk_get_rate(ip->clk);
> -
> value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
>
> if (value & BIT(IPROC_PWM_CTRL_EN_SHIFT(pwm->hwpwm)))
> @@ -99,6 +97,13 @@ static void iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> else
> state->polarity = PWM_POLARITY_INVERSED;
>
> + rate = clk_get_rate(ip->clk);
> + if (rate == 0) {
> + state->period = 0;
> + state->duty_cycle = 0;
> + return;
> + }
> +
> value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
> prescale = value >> IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm);
> prescale &= IPROC_PWM_PRESCALE_MAX;
>