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

[Claudiu.Beznea]

On 08.06.2022 11:20, Kavyasree Kotagiri - I30978 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@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/

"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@xxxxxxxxxxxxx/

> 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);
>