Re: [PATCH v2 2/5] pinctrl: pinconf-generic: Add API for pinmux propertity in DTS file

[Xianwei Zhao <xianwei.zhao@amlogic.com>]

Hi Jerome,
     Thanks for your reply.

On 2025/1/8 00:47, Jerome Brunet wrote:
> [ EXTERNAL EMAIL ]
> 
> On Thu 26 Dec 2024 at 15:57, Xianwei Zhao via B4 Relay <devnull+xianwei.zhao.amlogic.com@kernel.org> wrote:
> 
>> From: Xianwei Zhao <xianwei.zhao@amlogic.com>
>>
>> When describing pin mux func through pinmux propertity,
>> a standard API is added for support. The pinmux contains pin
>> identification and mux values, which can include multiple
>> pins. And groups configuration use other word. DTS such as:
>>
>> func-name {
>>        group_alias: group-name{
>>                pinmux= <pin_id << 8 | mux_value)>,
>>                        <pin_id << 8 | mux_value)>;
> 
> This representation does not seem very generic but more tailored to
> your use-case
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/Documentation/devicetree/bindings/pinctrl/pinmux-node.yaml?h=next-20250113

The document above includes a description of the pinmux property. This 
is not my personal usage but rather a common practice, as other 
manufacturers' drivers also use it in a similar way. However, the 
specific definitions within pinmux may vary between manufacturers.

> 
>>                bias-pull-up;
>>                drive-strength-microamp = <4000>;
> 
> If you want to add pinmux (aka alternate function) selection as a
> pinconf prop then I think there should be a single pinmux setting per
> group, and as many groups as you need per function defined.
> 
> something like
> 
> func-foo {
>          group-a {
>                  groups = "pin_a", "pin_b";
>                  bias-pull-up;
>                  alternate-function = <2>;
>          };
> 
>          group-b {
>                  groups = "pin_c"";
>                  bias-disable;
>                  alternate-function = <5>;
>          };
> };
> 
> Something similar is already done to handle different pin bias requirement
> on single function on amlogic platforms:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/amlogic/meson-axg.dtsi?h=v6.13-rc6#n421
> 
> 
>>        };
>> };
>>
>> Signed-off-by: Xianwei Zhao <xianwei.zhao@amlogic.com>
>> ---
>>   drivers/pinctrl/pinconf-generic.c       | 130 ++++++++++++++++++++++++++++++++
>>   drivers/pinctrl/pinconf.h               |   4 +
>>   include/linux/pinctrl/pinconf-generic.h |   4 +
>>   3 files changed, 138 insertions(+)
>>
>> diff --git a/drivers/pinctrl/pinconf-generic.c b/drivers/pinctrl/pinconf-generic.c
>> index 0b13d7f17b32..a4d3c12a80c4 100644
>> --- a/drivers/pinctrl/pinconf-generic.c
>> +++ b/drivers/pinctrl/pinconf-generic.c
>> @@ -233,6 +233,67 @@ static void parse_dt_cfg(struct device_node *np,
>>        }
>>   }
>>
>> +/**
>> + * pinconf_generic_parse_dt_pinmux()
>> + * parse the pinmux properties into generic pin mux values.
>> + * @np: node containing the pinmux properties
>> + * @pctldev: pincontrol device
>> + * @pid: array with pin identity entries
>> + * @pmux: array with pin mux value entries
>> + * @npins: number of pins
>> + *
>> + * pinmux propertity: mux value [0,7]bits and pin identity [8,31]bits.
>> + */
>> +int pinconf_generic_parse_dt_pinmux(struct device_node *np, struct device *dev,
>> +                                 unsigned int **pid, unsigned int **pmux,
>> +                                 unsigned int *npins)
>> +{
>> +     unsigned int *pid_t;
>> +     unsigned int *pmux_t;
>> +     struct property *prop;
>> +     unsigned int npins_t, i;
>> +     u32 value;
>> +     int ret;
>> +
>> +     prop = of_find_property(np, "pinmux", NULL);
>> +     if (!prop) {
>> +             dev_info(dev, "Missing pinmux property\n");
>> +             return -ENOENT;
>> +     }
>> +
>> +     if (!pid || !pmux || !npins) {
>> +             dev_err(dev, "paramers error\n");
>> +             return -EINVAL;
>> +     }
>> +
>> +     npins_t = prop->length / sizeof(u32);
>> +     pid_t = devm_kcalloc(dev, npins_t, sizeof(*pid_t), GFP_KERNEL);
>> +     pmux_t = devm_kcalloc(dev, npins_t, sizeof(*pmux_t), GFP_KERNEL);
>> +     if (!pid_t || !pmux_t) {
>> +             dev_err(dev, "kalloc memory fail\n");
>> +             return -ENOMEM;
>> +     }
>> +     for (i = 0; i < npins_t; i++) {
>> +             ret = of_property_read_u32_index(np, "pinmux", i, &value);
>> +             if (ret) {
>> +                     dev_err(dev, "get pinmux value fail\n");
>> +                     goto exit;
>> +             }
>> +             pmux_t[i] = value & 0xff;
>> +             pid_t[i] = (value >> 8) & 0xffffff;
>> +     }
>> +     *pid = pid_t;
>> +     *pmux = pmux_t;
>> +     *npins = npins_t;
>> +
>> +     return 0;
>> +exit:
>> +     devm_kfree(dev, pid_t);
>> +     devm_kfree(dev, pmux_t);
>> +     return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(pinconf_generic_parse_dt_pinmux);
>> +
>>   /**
>>    * pinconf_generic_parse_dt_config()
>>    * parse the config properties into generic pinconfig values.
>> @@ -295,6 +356,75 @@ int pinconf_generic_parse_dt_config(struct device_node *np,
>>   }
>>   EXPORT_SYMBOL_GPL(pinconf_generic_parse_dt_config);
>>
>> +int pinconf_generic_dt_node_to_map_pinmux(struct pinctrl_dev *pctldev,
>> +                                       struct device_node *np,
>> +                                       struct pinctrl_map **map,
>> +                                       unsigned int *num_maps)
>> +{
>> +     struct device *dev = pctldev->dev;
>> +     struct device_node *pnode;
>> +     unsigned long *configs = NULL;
>> +     unsigned int num_configs = 0;
>> +     struct property *prop;
>> +     unsigned int reserved_maps;
>> +     int reserve;
>> +     int ret;
>> +
>> +     prop = of_find_property(np, "pinmux", NULL);
>> +     if (!prop) {
>> +             dev_info(dev, "Missing pinmux property\n");
>> +             return -ENOENT;
>> +     }
>> +
>> +     pnode = of_get_parent(np);
>> +     if (!pnode) {
>> +             dev_info(dev, "Missing function node\n");
>> +             return -EINVAL;
>> +     }
>> +
>> +     reserved_maps = 0;
>> +     *map = NULL;
>> +     *num_maps = 0;
>> +
>> +     ret = pinconf_generic_parse_dt_config(np, pctldev, &configs,
>> +                                           &num_configs);
>> +     if (ret < 0) {
>> +             dev_err(dev, "%pOF: could not parse node property\n", np);
>> +             return ret;
>> +     }
>> +
>> +     reserve = 1;
>> +     if (num_configs)
>> +             reserve++;
>> +
>> +     ret = pinctrl_utils_reserve_map(pctldev, map, &reserved_maps,
>> +                                     num_maps, reserve);
>> +     if (ret < 0)
>> +             goto exit;
>> +
>> +     ret = pinctrl_utils_add_map_mux(pctldev, map,
>> +                                     &reserved_maps, num_maps, np->name,
>> +                                     pnode->name);
>> +     if (ret < 0)
>> +             goto exit;
>> +
>> +     if (num_configs) {
>> +             ret = pinctrl_utils_add_map_configs(pctldev, map, &reserved_maps,
>> +                                                 num_maps, np->name, configs,
>> +                                                 num_configs, PIN_MAP_TYPE_CONFIGS_GROUP);
>> +             if (ret < 0)
>> +                     goto exit;
>> +     }
>> +
>> +exit:
>> +     kfree(configs);
>> +     if (ret)
>> +             pinctrl_utils_free_map(pctldev, *map, *num_maps);
>> +
>> +     return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(pinconf_generic_dt_node_to_map_pinmux);
>> +
>>   int pinconf_generic_dt_subnode_to_map(struct pinctrl_dev *pctldev,
>>                struct device_node *np, struct pinctrl_map **map,
>>                unsigned int *reserved_maps, unsigned int *num_maps,
>> diff --git a/drivers/pinctrl/pinconf.h b/drivers/pinctrl/pinconf.h
>> index a14c950bc700..a171195b3615 100644
>> --- a/drivers/pinctrl/pinconf.h
>> +++ b/drivers/pinctrl/pinconf.h
>> @@ -138,4 +138,8 @@ int pinconf_generic_parse_dt_config(struct device_node *np,
>>                                    struct pinctrl_dev *pctldev,
>>                                    unsigned long **configs,
>>                                    unsigned int *nconfigs);
>> +
>> +int pinconf_generic_parse_dt_pinmux(struct device_node *np, struct device *dev,
>> +                                 unsigned int **pid, unsigned int **pmux,
>> +                                 unsigned int *npins);
>>   #endif
>> diff --git a/include/linux/pinctrl/pinconf-generic.h b/include/linux/pinctrl/pinconf-generic.h
>> index 53cfde98433d..1bcf071b860e 100644
>> --- a/include/linux/pinctrl/pinconf-generic.h
>> +++ b/include/linux/pinctrl/pinconf-generic.h
>> @@ -232,4 +232,8 @@ static inline int pinconf_generic_dt_node_to_map_all(struct pinctrl_dev *pctldev
>>                        PIN_MAP_TYPE_INVALID);
>>   }
>>
>> +int pinconf_generic_dt_node_to_map_pinmux(struct pinctrl_dev *pctldev,
>> +                                       struct device_node *np,
>> +                                       struct pinctrl_map **map,
>> +                                       unsigned int *num_maps);
>>   #endif /* __LINUX_PINCTRL_PINCONF_GENERIC_H */
> 
> --
> Jerome

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