[PATCH 5.17 0716/1126] pwm: lpc18xx-sct: Initialize driver data and hardware before pwmchip_add()

Greg Kroah-Hartman
2022-04-05T08:36:09Z

From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

[ Upstream commit 0401f24cd238ae200a23a13925f98de3d2c883b8 ]

When a driver calls pwmchip_add() it has to be prepared to immediately
get its callbacks called. So move allocation of driver data and hardware
initialization before the call to pwmchip_add().

This fixes a potential NULL pointer exception and a race condition on
register writes.

Fixes: 841e6f90bb78 ("pwm: NXP LPC18xx PWM/SCT driver")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/pwm/pwm-lpc18xx-sct.c | 20 +++++++++-----------
1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/drivers/pwm/pwm-lpc18xx-sct.c b/drivers/pwm/pwm-lpc18xx-sct.c
index 8e461f3baa05..8cc8ae16553c 100644
--- a/drivers/pwm/pwm-lpc18xx-sct.c
+++ b/drivers/pwm/pwm-lpc18xx-sct.c
@@ -395,12 +395,6 @@ static int lpc18xx_pwm_probe(struct platform_device *pdev)
lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_LIMIT,
BIT(lpc18xx_pwm->period_event));

- ret = pwmchip_add(&lpc18xx_pwm->chip);
- if (ret < 0) {
- dev_err(&pdev->dev, "pwmchip_add failed: %d\n", ret);
- goto disable_pwmclk;
- }
-
for (i = 0; i < lpc18xx_pwm->chip.npwm; i++) {
struct lpc18xx_pwm_data *data;

@@ -410,14 +404,12 @@ static int lpc18xx_pwm_probe(struct platform_device *pdev)
GFP_KERNEL);
if (!data) {
ret = -ENOMEM;
- goto remove_pwmchip;
+ goto disable_pwmclk;
}

pwm_set_chip_data(pwm, data);
}

- platform_set_drvdata(pdev, lpc18xx_pwm);
-
val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_CTRL);
val &= ~LPC18XX_PWM_BIDIR;
val &= ~LPC18XX_PWM_CTRL_HALT;
@@ -425,10 +417,16 @@ static int lpc18xx_pwm_probe(struct platform_device *pdev)
val |= LPC18XX_PWM_PRE(0);
lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CTRL, val);

+ ret = pwmchip_add(&lpc18xx_pwm->chip);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "pwmchip_add failed: %d\n", ret);
+ goto disable_pwmclk;
+ }
+
+ platform_set_drvdata(pdev, lpc18xx_pwm);
+
return 0;

-remove_pwmchip:
- pwmchip_remove(&lpc18xx_pwm->chip);
disable_pwmclk:
clk_disable_unprepare(lpc18xx_pwm->pwm_clk);
return ret;
--
2.34.1