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

[Kavyasree.Kotagiri]

> > 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@xxxxxxxxxxxxx>
> > ---
> > 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.
> 
https://lore.kernel.org/linux-arm-kernel/PH0PR11MB48724DE09A50D67F1EA9FBE092D89@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
As part of comments from Peter Rosin - Instead of using mux driver, This patch is introducing 
new dt-properties in atmel-flexom driver itlself to configure Flexcom shared registers. 
Based on the chip-select(0 or 1) to be mapped to flexcom shared pin, write to the
respective register. 
If you still have any questions, please comment.

> > +	}
> > +
> > +	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);