regulator: da91xx: Allow caching of buck registers when no GPIO input control is configured

André Svensson <andre.svensson@axis.com> says:

This series introduces a boolean DT property, dlg,no-gpio-control, for
the DA91xx regulators. Use this property to indicate that GPIO control
is not configured with the functions DVC/RELOAD/EN, allowing buck
registers to be cached.

The DA9121 driver checks dlg,no-gpio-control and updates regmap_config's
volatile_table if the property is present. Buck registers are removed
from the volatile_table if the property is present, enabling caching of
the registers, which removes I2C reads when performing an I2C write to
the buck registers.

Link: https://patch.msgid.link/20260320-no-gpio-control-v2-0-dbc938e462cb@axis.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: broonie

Documentation/devicetree/bindings/regulator/dlg,da9121.yaml

@@ -81,6 +81,14 @@ properties:
       Specify the polling period, measured in milliseconds, between interrupt status
       update checks. Range 1000-10000 ms.
 
+  dlg,no-gpio-control:
+    type: boolean
+    description: |
+      Available GPIO input pins of the regulator are strapped to fixed levels, therefore
+      GPIO configurable input functions, DVC/RELOAD/EN, cannot dynamically update BUCK
+      registers. GPIO pins connected as output pins are not required to be strapped to a
+      fixed level. Not allowed together with enable-gpios.
+
   regulators:
     type: object
     additionalProperties: false
@@ -134,6 +142,17 @@ allOf:
           properties:
             buck2: false
 
+  - if:
+      required:
+        - dlg,no-gpio-control
+    then:
+      properties:
+        regulators:
+          patternProperties:
+            "^buck([1-2])$":
+              properties:
+                enable-gpios: false
+
 additionalProperties: false
 
 examples:
@@ -168,6 +187,36 @@ examples:
       };
     };
 
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    #include <dt-bindings/regulator/dlg,da9121-regulator.h>
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+      pmic@68 {
+        compatible = "dlg,da9121";
+        reg = <0x68>;
+
+        interrupt-parent = <&gpio6>;
+        interrupts = <11 IRQ_TYPE_LEVEL_LOW>;
+
+        dlg,irq-polling-delay-passive-ms = <2000>;
+        dlg,no-gpio-control;
+
+        regulators {
+          DA9121_BUCK: buck1 {
+            regulator-name = "BUCK1";
+            regulator-min-microvolt = <300000>;
+            regulator-max-microvolt = <1900000>;
+            regulator-min-microamp = <7000000>;
+            regulator-max-microamp = <20000000>;
+            regulator-boot-on;
+            regulator-initial-mode = <DA9121_BUCK_MODE_AUTO>;
+          };
+        };
+      };
+    };
+
   - |
     #include <dt-bindings/gpio/gpio.h>
     #include <dt-bindings/interrupt-controller/irq.h>

drivers/regulator/da9121-regulator.c

@@ -400,8 +400,14 @@ static int da9121_of_parse_cb(struct device_node *np,
 						GPIOD_OUT_HIGH |
 						GPIOD_FLAGS_BIT_NONEXCLUSIVE,
 						"da9121-enable");
-	if (!IS_ERR(ena_gpiod))
+	if (!IS_ERR(ena_gpiod)) {
+		if (of_property_read_bool(chip->dev->of_node, "dlg,no-gpio-control")) {
+			gpiod_put(ena_gpiod);
+			dev_err(chip->dev, "dlg,no-gpio-control conflicts with enable-gpios\n");
+			return -EINVAL;
+		}
 		config->ena_gpiod = ena_gpiod;
+	}
 
 	if (variant_parameters[chip->variant_id].num_bucks == 2) {
 		uint32_t ripple_cancel;
@@ -864,6 +870,21 @@ static const struct regmap_access_table da9121_volatile_table = {
 	.n_yes_ranges = ARRAY_SIZE(da9121_volatile_ranges),
 };
 
+/*
+ * When GPIO functions DVC/RELOAD/EN are not used, the registers in the range
+ * DA9121_REG_BUCK_BUCK1_0 to DA9121_REG_BUCK_BUCK1_6 need not be volatile
+ * because register writes to these registers can only be performed via I2C.
+ */
+static const struct regmap_range da9121_volatile_ranges_no_gpio_ctrl[] = {
+	regmap_reg_range(DA9121_REG_SYS_STATUS_0, DA9121_REG_SYS_EVENT_2),
+	regmap_reg_range(DA9121_REG_SYS_GPIO0_0, DA9121_REG_SYS_GPIO2_1),
+};
+
+static const struct regmap_access_table da9121_volatile_table_no_gpio_ctrl = {
+	.yes_ranges = da9121_volatile_ranges_no_gpio_ctrl,
+	.n_yes_ranges = ARRAY_SIZE(da9121_volatile_ranges_no_gpio_ctrl),
+};
+
 /* DA9121 regmap config for 1 channel variants */
 static const struct regmap_config da9121_1ch_regmap_config = {
 	.reg_bits = 8,
@@ -994,40 +1015,48 @@ static int da9121_assign_chip_model(struct i2c_client *i2c,
 			struct da9121 *chip)
 {
 	const struct regmap_config *regmap;
+	struct regmap_config regmap_config_1ch = da9121_1ch_regmap_config;
+	struct regmap_config regmap_config_2ch = da9121_2ch_regmap_config;
+
 	int ret = 0;
 
 	chip->dev = &i2c->dev;
 
+	if (of_property_read_bool(i2c->dev.of_node, "dlg,no-gpio-control")) {
+		regmap_config_1ch.volatile_table = &da9121_volatile_table_no_gpio_ctrl;
+		regmap_config_2ch.volatile_table = &da9121_volatile_table_no_gpio_ctrl;
+	}
+
 	/* Use configured subtype to select the regulator descriptor index and
 	 * register map, common to both consumer and automotive grade variants
 	 */
 	switch (chip->subvariant_id) {
 	case DA9121_SUBTYPE_DA9121:
 	case DA9121_SUBTYPE_DA9130:
 		chip->variant_id = DA9121_TYPE_DA9121_DA9130;
-		regmap = &da9121_1ch_regmap_config;
+		regmap = &regmap_config_1ch;
 		break;
 	case DA9121_SUBTYPE_DA9217:
 		chip->variant_id = DA9121_TYPE_DA9217;
-		regmap = &da9121_1ch_regmap_config;
+		regmap = &regmap_config_1ch;
 		break;
 	case DA9121_SUBTYPE_DA9122:
 	case DA9121_SUBTYPE_DA9131:
 		chip->variant_id = DA9121_TYPE_DA9122_DA9131;
-		regmap = &da9121_2ch_regmap_config;
+		regmap = &regmap_config_2ch;
 		break;
 	case DA9121_SUBTYPE_DA9220:
 	case DA9121_SUBTYPE_DA9132:
 		chip->variant_id = DA9121_TYPE_DA9220_DA9132;
-		regmap = &da9121_2ch_regmap_config;
+		regmap = &regmap_config_2ch;
 		break;
 	case DA9121_SUBTYPE_DA9141:
 		chip->variant_id = DA9121_TYPE_DA9141;
-		regmap = &da9121_1ch_regmap_config;
+		regmap = &regmap_config_1ch;
 		break;
 	case DA9121_SUBTYPE_DA9142:
 		chip->variant_id = DA9121_TYPE_DA9142;
-		regmap = &da9121_2ch_regmap_config;
+		regmap = &regmap_config_2ch;
 		break;
 	default:
 		return -EINVAL;