linux-kernel - Re: [PATCH v2 2/2] Add PWM fan controller driver for LGM SoC

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Date:   Thu, 18 Jun 2020 14:25:50 +0200
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     Rahul Tanwar <rahul.tanwar@...ux.intel.com>,
        u.kleine-koenig@...gutronix.de, linux-pwm@...r.kernel.org
Cc:     thierry.reding@...il.com, robh+dt@...nel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        andriy.shevchenko@...el.com, songjun.Wu@...el.com,
        cheol.yong.kim@...el.com, qi-ming.wu@...el.com,
        rahul.tanwar.linux@...il.com
Subject: Re: [PATCH v2 2/2] Add PWM fan controller driver for LGM SoC

Hi Rahul,

On Thu, 2020-06-18 at 20:05 +0800, Rahul Tanwar wrote:
> Intel Lightning Mountain(LGM) SoC contains a PWM fan controller.
> This PWM controller does not have any other consumer, it is a
> dedicated PWM controller for fan attached to the system. Add
> driver for this PWM fan controller.
> 
> Signed-off-by: Rahul Tanwar <rahul.tanwar@...ux.intel.com>
> ---
>  drivers/pwm/Kconfig         |   9 +
>  drivers/pwm/Makefile        |   1 +
>  drivers/pwm/pwm-intel-lgm.c | 400 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 410 insertions(+)
>  create mode 100644 drivers/pwm/pwm-intel-lgm.c
> 
[...]
> diff --git a/drivers/pwm/pwm-intel-lgm.c b/drivers/pwm/pwm-intel-lgm.c
> new file mode 100644
> index 000000000000..3c7077acb161
> --- /dev/null
> +++ b/drivers/pwm/pwm-intel-lgm.c
> @@ -0,0 +1,400 @@
[...]
> +static int lgm_pwm_probe(struct platform_device *pdev)
> +{
> +	struct lgm_pwm_chip *pc;
> +	struct device *dev = &pdev->dev;
> +	void __iomem *io_base;
> +	int ret;
> +
> +	pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL);
> +	if (!pc)
> +		return -ENOMEM;
> +
> +	io_base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(io_base))
> +		return PTR_ERR(io_base);
> +
> +	pc->regmap = devm_regmap_init_mmio(dev, io_base, &pwm_regmap_config);
> +	if (IS_ERR(pc->regmap)) {
> +		ret = PTR_ERR(pc->regmap);
> +		dev_err(dev, "failed to init register map: %pe\n", pc->regmap);
> +		return ret;
> +	}
> +
> +	pc->clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(pc->clk)) {
> +		ret = PTR_ERR(pc->clk);
> +		dev_err(dev, "failed to get clock: %pe\n", pc->clk);
> +		return ret;
> +	}
> +
> +	pc->rst = devm_reset_control_get(dev, NULL);
> +	if (IS_ERR(pc->rst)) {
> +		ret = PTR_ERR(pc->rst);
> +		dev_err(dev, "failed to get reset control: %pe\n", pc->rst);
> +		return ret;
> +	}

Please use devm_reset_control_get_exclusive() to make it explicit an
that exclusive reset control is requested. Given how the reset control
is used, I think this driver could also use
devm_reset_control_get_shared() to potentially allow sharing a reset
line with other devices.

regards
Philipp