linux-kernel - Re: [PATCH v2 3/3] mfd: atmel-flexcom: Add support for lan966x flexcom chip-select configuration

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Message-ID: <9cf14336-16c3-5df5-b235-3f988d8b5151@microchip.com>
Date:   Wed, 8 Jun 2022 07:35:02 +0000
From:   <Claudiu.Beznea@...rochip.com>
To:     <Kavyasree.Kotagiri@...rochip.com>,
        <krzysztof.kozlowski+dt@...aro.org>, <Nicolas.Ferre@...rochip.com>,
        <alexandre.belloni@...tlin.com>
CC:     <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <UNGLinuxDriver@...rochip.com>
Subject: Re: [PATCH v2 3/3] mfd: atmel-flexcom: Add support for lan966x
 flexcom chip-select configuration

On 07.06.2022 17:47, Kavyasree Kotagiri wrote:
> LAN966x SoC have 5 flexcoms. Each flexcom has 2 chip-selects.
> For each chip select of each flexcom there is a configuration
> register FLEXCOM_SHARED[0-4]:SS_MASK[0-1]. The width of
> configuration register is 21 because there are 21 shared pins
> on each of which the chip select can be mapped. Each bit of the
> register represents a different FLEXCOM_SHARED pin.
> 
> Signed-off-by: Kavyasree Kotagiri <kavyasree.kotagiri@...rochip.com>
> ---
> v1 -> v2:
>  - use GENMASK for mask, macros for maximum allowed values.
>  - use u32 values for flexcom chipselects instead of strings.
>  - disable clock in case of errors.
> 
>  drivers/mfd/atmel-flexcom.c | 93 ++++++++++++++++++++++++++++++++++++-
>  1 file changed, 92 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mfd/atmel-flexcom.c b/drivers/mfd/atmel-flexcom.c
> index 33caa4fba6af..ac700a85b46f 100644
> --- a/drivers/mfd/atmel-flexcom.c
> +++ b/drivers/mfd/atmel-flexcom.c
> @@ -28,15 +28,68 @@
>  #define FLEX_MR_OPMODE(opmode)	(((opmode) << FLEX_MR_OPMODE_OFFSET) &	\
>  				 FLEX_MR_OPMODE_MASK)
>  
> +/* LAN966x flexcom shared register offsets */
> +#define FLEX_SHRD_SS_MASK_0	0x0
> +#define FLEX_SHRD_SS_MASK_1	0x4
> +#define FLEX_SHRD_PIN_MAX	20
> +#define FLEX_CS_MAX		1
> +#define FLEX_SHRD_MASK		GENMASK(20, 0)
> +
> +struct atmel_flex_caps {
> +	bool has_flx_cs;
> +};
> +
>  struct atmel_flexcom {
>  	void __iomem *base;
> +	void __iomem *flexcom_shared_base;
>  	u32 opmode;
>  	struct clk *clk;
>  };
>  
> +static int atmel_flexcom_lan966x_cs_config(struct platform_device *pdev)
> +{
> +	struct atmel_flexcom *ddata = dev_get_drvdata(&pdev->dev);
> +	struct device_node *np = pdev->dev.of_node;
> +	u32 flx_shrd_pins[2], flx_cs[2], val;
> +	int err, i, count;
> +
> +	count = of_property_count_u32_elems(np, "microchip,flx-shrd-pins");
> +	if (count <= 0 || count > 2) {
> +		dev_err(&pdev->dev, "Invalid %s property (%d)\n", "flx-shrd-pins",
> +				count);
> +		return -EINVAL;
> +	}
> +
> +	err = of_property_read_u32_array(np, "microchip,flx-shrd-pins", flx_shrd_pins, count);
> +	if (err)
> +		return err;
> +
> +	err = of_property_read_u32_array(np, "microchip,flx-cs", flx_cs, count);
> +	if (err)
> +		return err;
> +
> +	for (i = 0; i < count; i++) {
> +		if (flx_shrd_pins[i] > FLEX_SHRD_PIN_MAX)
> +			return -EINVAL;
> +
> +		if (flx_cs[i] > FLEX_CS_MAX)
> +			return -EINVAL;
> +
> +		val = ~(1 << flx_shrd_pins[i]) & FLEX_SHRD_MASK;
> +
> +		if (flx_cs[i] == 0)
> +			writel(val, ddata->flexcom_shared_base + FLEX_SHRD_SS_MASK_0);
> +		else
> +			writel(val, ddata->flexcom_shared_base + FLEX_SHRD_SS_MASK_1);

There is still an open question on this topic from previous version.

> +	}
> +
> +	return 0;
> +}
> +
>  static int atmel_flexcom_probe(struct platform_device *pdev)
>  {
>  	struct device_node *np = pdev->dev.of_node;
> +	const struct atmel_flex_caps *caps;
>  	struct resource *res;
>  	struct atmel_flexcom *ddata;
>  	int err;
> @@ -76,13 +129,51 @@ static int atmel_flexcom_probe(struct platform_device *pdev)
>  	 */
>  	writel(FLEX_MR_OPMODE(ddata->opmode), ddata->base + FLEX_MR);
>  
> +	caps = of_device_get_match_data(&pdev->dev);
> +	if (!caps) {
> +		dev_err(&pdev->dev, "Could not retrieve flexcom caps\n");
> +		clk_disable_unprepare(ddata->clk);

Could you keep a common path to disable the clock? A goto label something
like this:
		ret = -EINVAL;
		got clk_disable_unprepare;

> +		return -EINVAL;
> +	}
> +
> +	if (caps->has_flx_cs) {
> +		ddata->flexcom_shared_base = devm_platform_get_and_ioremap_resource(pdev, 1, NULL);
> +		if (IS_ERR(ddata->flexcom_shared_base)) {
> +			clk_disable_unprepare(ddata->clk);
> +			return dev_err_probe(&pdev->dev,
> +					PTR_ERR(ddata->flexcom_shared_base),
> +					"failed to get flexcom shared base address\n");
			ret = dev_err_probe(...);
			goto clk_disable_unprepare;
> +		}
> +
> +		err = atmel_flexcom_lan966x_cs_config(pdev);
> +		if (err) {
> +			clk_disable_unprepare(ddata->clk);
> +			return err;
			goto clk_disable_unprepare;
> +		}
> +	}
> +

clk_unprepare:
>  	clk_disable_unprepare(ddata->clk);
	if (ret)
		return ret;
>  
>  	return devm_of_platform_populate(&pdev->dev);
>  }
>  
> +static const struct atmel_flex_caps atmel_flexcom_caps = {};
> +
> +static const struct atmel_flex_caps lan966x_flexcom_caps = {
> +	.has_flx_cs = true,
> +};
> +
>  static const struct of_device_id atmel_flexcom_of_match[] = {
> -	{ .compatible = "atmel,sama5d2-flexcom" },
> +	{
> +		.compatible = "atmel,sama5d2-flexcom",
> +		.data = &atmel_flexcom_caps,
> +	},
> +
> +	{
> +		.compatible = "microchip,lan966x-flexcom",
> +		.data = &lan966x_flexcom_caps,
> +	},
> +
>  	{ /* sentinel */ }
>  };
>  MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match);