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    Subject[PATCH 5.4 228/475] pwm: lpc18xx-sct: Initialize driver data and hardware before pwmchip_add()
    Date
    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 5ff11145c1a3..9b15b6a79082 100644
    --- a/drivers/pwm/pwm-lpc18xx-sct.c
    +++ b/drivers/pwm/pwm-lpc18xx-sct.c
    @@ -400,12 +400,6 @@ 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;

    @@ -415,14 +409,12 @@ 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;
    @@ -430,10 +422,16 @@ 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


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