linux-kernel - [PATCH v4] pwm: bcm-iproc: handle clk_get

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Message-Id: <20200718044606.18739-1-scott.branden@broadcom.com>
Date:   Fri, 17 Jul 2020 21:46:06 -0700
From:   Scott Branden <scott.branden@...adcom.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Lee Jones <lee.jones@...aro.org>
Cc:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        BCM Kernel Feedback <bcm-kernel-feedback-list@...adcom.com>,
        linux-pwm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Rayagonda Kokatanur <rayagonda.kokatanur@...adcom.com>,
        Scott Branden <scott.branden@...adcom.com>
Subject: [PATCH v4] pwm: bcm-iproc: handle clk_get_rate() return

From: Rayagonda Kokatanur <rayagonda.kokatanur@...adcom.com>

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 <rayagonda.kokatanur@...adcom.com>
Signed-off-by: Scott Branden <scott.branden@...adcom.com>
Reviewed-by: Ray Jui <ray.jui@...adcom.com>

---
Changes from v3: fixed typo in commit message: Reviewed-off-by.
Hopefully everything clean now.
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