From 0401f24cd238ae200a23a13925f98de3d2c883b8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>
Date: Wed, 10 Nov 2021 09:49:48 +0100
Subject: [PATCH] pwm: lpc18xx-sct: Initialize driver data and hardware before pwmchip_add()
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Git-commit: 0401f24cd238ae200a23a13925f98de3d2c883b8
Patch-mainline: v5.18-rc1
References: git-fixes

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>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 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;
-- 
2.31.1