On Wed, Jun 10, 2015 at 05:04:57PM +0200, Ludovic Desroches wrote:
> Using a string to describe a pin in the device tree can be not enough.
> Some controllers may need extra information to fully describe a pin. It
> concerns mainly controllers which have a per pin muxing approach which
> don't fit well the notions of groups and functions.
> Instead of using a pin name, a 32 bit value is used. The 16 least
> significant bits are used for the pin number. Other 16 bits can be used to
> store extra parameters.
In the Mediatek driver we use 'pinmux' as name for the property
containing the combined pin number / mux value defines. 'pinmux' better
describes what it is...
> +
> + if (pctldesc->complex_pin_desc)
> + ret = of_property_count_u32_elems(np, "pins");
> + else
> + ret = of_property_count_strings(np, "pins");
... and has the advantage that you don't have to pass in a
complex_pin_desc variable from the driver as the different property
name inherently carries this information. 'pins' can then stay a
property containing only strings.
> if (ret < 0) {
> ret = of_property_count_strings(np, "groups");
> if (ret < 0)
> @@ -297,11 +305,12 @@ int pinconf_generic_dt_subnode_to_map(struct
> pinctrl_dev *pctldev,
> if (type == PIN_MAP_TYPE_INVALID)
> type = PIN_MAP_TYPE_CONFIGS_GROUP;
> subnode_target_type = "groups";
> + pins_prop = false;
> } else {
> if (type == PIN_MAP_TYPE_INVALID)
> type = PIN_MAP_TYPE_CONFIGS_PIN;
> }
> - strings_count = ret;
> + items_count = ret;
>
> ret = of_property_read_string(np, "function", &function);
> if (ret < 0) {
> @@ -326,17 +335,31 @@ int pinconf_generic_dt_subnode_to_map(struct
> pinctrl_dev *pctldev,
> if (num_configs)
> reserve++;
>
> - reserve *= strings_count;
> + reserve *= items_count;
>
> ret = pinctrl_utils_reserve_map(pctldev, map, reserved_maps,
> num_maps, reserve);
> if (ret < 0)
> goto exit;
>
> - of_property_for_each_string(np, subnode_target_type, prop, group) {
> + items_name = kmalloc_array(items_count, sizeof(char *), GFP_KERNEL);
> + if (!items_name)
> + goto exit;
> + if (pctldesc->complex_pin_desc && pins_prop) {
> + of_property_for_each_u32(np, subnode_target_type, prop, cur,
> val) {
> + pin_id = val & PINCTRL_PIN_MASK;
> + items_name[i++] = pctldesc->pins[pin_id].name;
> + }
I don't like that even though pins have numbers here they are converted
to strings which the driver later has to search in a list just to
convert it back into the number. This is quite inefficient.
I guess this could be optimized later, but it would be nice to have the
pin number directly in the driver.
Sascha
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