Date:   Thu, 9 Jun 2022 05:18:28 +0000
From:   <Kavyasree.Kotagiri@...rochip.com>
To:     <Claudiu.Beznea@...rochip.com>
CC:     <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <UNGLinuxDriver@...rochip.com>,
        <krzysztof.kozlowski+dt@...aro.org>, <Nicolas.Ferre@...rochip.com>,
        <alexandre.belloni@...tlin.com>
Subject: RE: [PATCH v2 3/3] mfd: atmel-flexcom: Add support for lan966x
 flexcom chip-select configuration

> >>> 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.
> >>
> > https://lore.kernel.org/linux-arm-
> kernel/PH0PR11MB48724DE09A50D67F1EA9FBE092D89@...PR11MB4872.n
> amprd11.prod.outlook.com/
> 
> "previous version" meant for me this the one at [1]... Another point that
> the versioning of this series is bad.
> 
> The question was the following:
> 
> "I may miss something but I don't see here the approach you introduced in
> [1]:
> 
> +			err = mux_control_select(flx_mux, args.args[0]);
> +			if (!err) {
> +				mux_control_deselect(flx_mux);
> "
> 
> As I had in mind that you said you need mux_control_deselect() because
> your
> serial remain blocked otherwise (but I don't find that in the comments of
> [1]). And I don't see something similar to mux_control_deselect() being
> called in this patch.
> 
> [1]
> https://lore.kernel.org/linux-arm-kernel/5f9fcc33-cc0f-c404-cf7f-
> cb73f60154ff@...rochip.com/
> 
> > 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.
> >
https://lore.kernel.org/linux-arm-kernel/PH0PR11MB48724DE09A50D67F1EA9FBE092D89@PH0PR11MB4872.namprd11.prod.outlook.com/
To avoid confusion, I stopped continuing with above patch versioning(mux driver approach).
I started new patch series in which I am configuring FLEXCOM_SHARED[0-4]:SS_MASK[0-1]
registers in atmel-flexcom.c driver using new DT-properties, mux driver approach is no more followed
as suggested by Peter Rosin:
"
> If you are content with just programming a fixed set of values to
> a couple of registers depending on how the board is wired, some
> extra DT property on some node related to the flexcom seems like
> a better fit than a mux driver.
Based on your inputs, I planned to send a new patch with new DT properties
introduced in atmel-flexcom.c driver rather than mux driver.

Thanks,
Kavya
"

Thanks,
Kavya

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

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