pinctrl: pinconf-generic: Handle string values for generic properties

Allow a generic pinconf property to specify its argument as one of
the strings in a match list.
Convert the matching string to an integer value using the index in
the list, then keep using this value in the generic pinconf code.

Signed-off-by: Antonio Borneo <antonio.borneo@foss.st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Author: AntonioBorneo

drivers/pinctrl/pinconf-generic.c

@@ -65,11 +65,12 @@ static void pinconf_generic_dump_one(struct pinctrl_dev *pctldev,
 	int i;
 
 	for (i = 0; i < nitems; i++) {
+		const struct pin_config_item *item = &items[i];
 		unsigned long config;
 		int ret;
 
 		/* We want to check out this parameter */
-		config = pinconf_to_config_packed(items[i].param, 0);
+		config = pinconf_to_config_packed(item->param, 0);
 		if (gname)
 			ret = pin_config_group_get(dev_name(pctldev->dev),
 						   gname, &config);
@@ -86,15 +87,22 @@ static void pinconf_generic_dump_one(struct pinctrl_dev *pctldev,
 		if (*print_sep)
 			seq_puts(s, ", ");
 		*print_sep = 1;
-		seq_puts(s, items[i].display);
+		seq_puts(s, item->display);
 		/* Print unit if available */
-		if (items[i].has_arg) {
+		if (item->has_arg) {
 			u32 val = pinconf_to_config_argument(config);
 
-			if (items[i].format)
-				seq_printf(s, " (%u %s)", val, items[i].format);
+			if (item->format)
+				seq_printf(s, " (%u %s)", val, item->format);
 			else
 				seq_printf(s, " (0x%x)", val);
+
+			if (item->values && item->num_values) {
+				if (val < item->num_values)
+					seq_printf(s, " \"%s\"", item->values[val]);
+				else
+					seq_puts(s, " \"(unknown)\"");
+			}
 		}
 	}
 }
@@ -205,10 +213,10 @@ static const struct pinconf_generic_params dt_params[] = {
  * @ncfg. @ncfg is updated to reflect the number of entries after parsing. @cfg
  * needs to have enough memory allocated to hold all possible entries.
  */
-static void parse_dt_cfg(struct device_node *np,
-			 const struct pinconf_generic_params *params,
-			 unsigned int count, unsigned long *cfg,
-			 unsigned int *ncfg)
+static int parse_dt_cfg(struct device_node *np,
+			const struct pinconf_generic_params *params,
+			unsigned int count, unsigned long *cfg,
+			unsigned int *ncfg)
 {
 	int i;
 
@@ -217,7 +225,19 @@ static void parse_dt_cfg(struct device_node *np,
 		int ret;
 		const struct pinconf_generic_params *par = &params[i];
 
-		ret = of_property_read_u32(np, par->property, &val);
+		if (par->values && par->num_values) {
+			ret = fwnode_property_match_property_string(of_fwnode_handle(np),
+								    par->property,
+								    par->values, par->num_values);
+			if (ret == -ENOENT)
+				return ret;
+			if (ret >= 0) {
+				val = ret;
+				ret = 0;
+			}
+		} else {
+			ret = of_property_read_u32(np, par->property, &val);
+		}
 
 		/* property not found */
 		if (ret == -EINVAL)
@@ -231,6 +251,8 @@ static void parse_dt_cfg(struct device_node *np,
 		cfg[*ncfg] = pinconf_to_config_packed(par->param, val);
 		(*ncfg)++;
 	}
+
+	return 0;
 }
 
 /**
@@ -323,13 +345,16 @@ int pinconf_generic_parse_dt_config(struct device_node *np,
 	if (!cfg)
 		return -ENOMEM;
 
-	parse_dt_cfg(np, dt_params, ARRAY_SIZE(dt_params), cfg, &ncfg);
+	ret = parse_dt_cfg(np, dt_params, ARRAY_SIZE(dt_params), cfg, &ncfg);
+	if (ret)
+		return ret;
 	if (pctldev && pctldev->desc->num_custom_params &&
-		pctldev->desc->custom_params)
-		parse_dt_cfg(np, pctldev->desc->custom_params,
-			     pctldev->desc->num_custom_params, cfg, &ncfg);
-
-	ret = 0;
+		pctldev->desc->custom_params) {
+		ret = parse_dt_cfg(np, pctldev->desc->custom_params,
+				   pctldev->desc->num_custom_params, cfg, &ncfg);
+		if (ret)
+			return ret;
+	}
 
 	/* no configs found at all */
 	if (ncfg == 0) {

include/linux/pinctrl/pinconf-generic.h

@@ -181,21 +181,28 @@ static inline unsigned long pinconf_to_config_packed(enum pin_config_param param
 	return PIN_CONF_PACKED(param, argument);
 }
 
-#define PCONFDUMP(a, b, c, d) {					\
-	.param = a, .display = b, .format = c, .has_arg = d	\
+#define PCONFDUMP_WITH_VALUES(a, b, c, d, e, f) {		\
+	.param = a, .display = b, .format = c, .has_arg = d,	\
+	.values = e, .num_values = f				\
 	}
 
+#define PCONFDUMP(a, b, c, d)	PCONFDUMP_WITH_VALUES(a, b, c, d, NULL, 0)
+
 struct pin_config_item {
 	const enum pin_config_param param;
 	const char * const display;
 	const char * const format;
 	bool has_arg;
+	const char * const *values;
+	size_t num_values;
 };
 
 struct pinconf_generic_params {
 	const char * const property;
 	enum pin_config_param param;
 	u32 default_value;
+	const char * const *values;
+	size_t num_values;
 };
 
 int pinconf_generic_dt_subnode_to_map(struct pinctrl_dev *pctldev,