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

[Xianwei Zhao <xianwei.zhao@xxxxxxxxxxx>]

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@xxxxxxxxxx> wrote:
>
> > From: Xianwei Zhao <xianwei.zhao@xxxxxxxxxxx>
> >
> > 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@xxxxxxxxxxx>
> > ---
> >   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