regulator: bd718x7: Support SNVS low power state

read ROHM BD71837 / BD71847 specific device tree bindings for
controlling the PMIC shutdown/reset states and voltages for
different HW states. The PMIC was designed to be used with NXP
i.MX8 SoC and it supports SNVS low power state which seems to
be typical for NXP i.MX SoCs. However, when SNVS is used we must
not allow SW to control enabling/disabling those regulators which
are crucial for system to boot as there is a HW limitation which
causes SW controlled regulators to be kept shut down after SNVS
reset.

Allow setting the SNVS to be used as reset target state and allow
marking those regulators which are critical for boot.
Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Tested-by: Angus Ainslie <angus@akkea.ca>
Reviewed-by: Angus Ainslie <angus@akkea.ca>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/bd718x7-regulator.c

@@ -350,6 +350,135 @@ static const struct reg_init bd71837_ldo6_inits[] = {
 	},
 };
 
+#define NUM_DVS_BUCKS 4
+
+struct of_dvs_setting {
+	const char *prop;
+	unsigned int reg;
+};
+
+static int set_dvs_levels(const struct of_dvs_setting *dvs,
+			  struct device_node *np,
+			  const struct regulator_desc *desc,
+			  struct regmap *regmap)
+{
+	int ret, i;
+	unsigned int uv;
+
+	ret = of_property_read_u32(np, dvs->prop, &uv);
+	if (ret) {
+		if (ret != -EINVAL)
+			return ret;
+		return 0;
+	}
+
+	for (i = 0; i < desc->n_voltages; i++) {
+		ret = regulator_desc_list_voltage_linear_range(desc, i);
+		if (ret < 0)
+			continue;
+		if (ret == uv) {
+			i <<= ffs(desc->vsel_mask) - 1;
+			ret = regmap_update_bits(regmap, dvs->reg,
+						 DVS_BUCK_RUN_MASK, i);
+			break;
+		}
+	}
+	return ret;
+}
+
+static int buck4_set_hw_dvs_levels(struct device_node *np,
+			    const struct regulator_desc *desc,
+			    struct regulator_config *cfg)
+{
+	int ret, i;
+	const struct of_dvs_setting dvs[] = {
+		{
+			.prop = "rohm,dvs-run-voltage",
+			.reg = BD71837_REG_BUCK4_VOLT_RUN,
+		},
+	};
+
+	for (i = 0; i < ARRAY_SIZE(dvs); i++) {
+		ret = set_dvs_levels(&dvs[i], np, desc, cfg->regmap);
+		if (ret)
+			break;
+	}
+	return ret;
+}
+static int buck3_set_hw_dvs_levels(struct device_node *np,
+			    const struct regulator_desc *desc,
+			    struct regulator_config *cfg)
+{
+	int ret, i;
+	const struct of_dvs_setting dvs[] = {
+		{
+			.prop = "rohm,dvs-run-voltage",
+			.reg = BD71837_REG_BUCK3_VOLT_RUN,
+		},
+	};
+
+	for (i = 0; i < ARRAY_SIZE(dvs); i++) {
+		ret = set_dvs_levels(&dvs[i], np, desc, cfg->regmap);
+		if (ret)
+			break;
+	}
+	return ret;
+}
+
+static int buck2_set_hw_dvs_levels(struct device_node *np,
+			    const struct regulator_desc *desc,
+			    struct regulator_config *cfg)
+{
+	int ret, i;
+	const struct of_dvs_setting dvs[] = {
+		{
+			.prop = "rohm,dvs-run-voltage",
+			.reg = BD718XX_REG_BUCK2_VOLT_RUN,
+		},
+		{
+			.prop = "rohm,dvs-idle-voltage",
+			.reg = BD718XX_REG_BUCK2_VOLT_IDLE,
+		},
+	};
+
+
+
+	for (i = 0; i < ARRAY_SIZE(dvs); i++) {
+		ret = set_dvs_levels(&dvs[i], np, desc, cfg->regmap);
+		if (ret)
+			break;
+	}
+	return ret;
+}
+
+static int buck1_set_hw_dvs_levels(struct device_node *np,
+			    const struct regulator_desc *desc,
+			    struct regulator_config *cfg)
+{
+	int ret, i;
+	const struct of_dvs_setting dvs[] = {
+		{
+			.prop = "rohm,dvs-run-voltage",
+			.reg = BD718XX_REG_BUCK1_VOLT_RUN,
+		},
+		{
+			.prop = "rohm,dvs-idle-voltage",
+			.reg = BD718XX_REG_BUCK1_VOLT_IDLE,
+		},
+		{
+			.prop = "rohm,dvs-suspend-voltage",
+			.reg = BD718XX_REG_BUCK1_VOLT_SUSP,
+		},
+	};
+
+	for (i = 0; i < ARRAY_SIZE(dvs); i++) {
+		ret = set_dvs_levels(&dvs[i], np, desc, cfg->regmap);
+		if (ret)
+			break;
+	}
+	return ret;
+}
+
 static const struct bd718xx_regulator_data bd71847_regulators[] = {
 	{
 		.desc = {
@@ -368,6 +497,7 @@ static const struct bd718xx_regulator_data bd71847_regulators[] = {
 			.enable_reg = BD718XX_REG_BUCK1_CTRL,
 			.enable_mask = BD718XX_BUCK_EN,
 			.owner = THIS_MODULE,
+			.of_parse_cb = buck1_set_hw_dvs_levels,
 		},
 		.init = {
 			.reg = BD718XX_REG_BUCK1_CTRL,
@@ -391,6 +521,7 @@ static const struct bd718xx_regulator_data bd71847_regulators[] = {
 			.enable_reg = BD718XX_REG_BUCK2_CTRL,
 			.enable_mask = BD718XX_BUCK_EN,
 			.owner = THIS_MODULE,
+			.of_parse_cb = buck2_set_hw_dvs_levels,
 		},
 		.init = {
 			.reg = BD718XX_REG_BUCK2_CTRL,
@@ -662,6 +793,7 @@ static const struct bd718xx_regulator_data bd71837_regulators[] = {
 			.enable_reg = BD718XX_REG_BUCK1_CTRL,
 			.enable_mask = BD718XX_BUCK_EN,
 			.owner = THIS_MODULE,
+			.of_parse_cb = buck1_set_hw_dvs_levels,
 		},
 		.init = {
 			.reg = BD718XX_REG_BUCK1_CTRL,
@@ -685,6 +817,7 @@ static const struct bd718xx_regulator_data bd71837_regulators[] = {
 			.enable_reg = BD718XX_REG_BUCK2_CTRL,
 			.enable_mask = BD718XX_BUCK_EN,
 			.owner = THIS_MODULE,
+			.of_parse_cb = buck2_set_hw_dvs_levels,
 		},
 		.init = {
 			.reg = BD718XX_REG_BUCK2_CTRL,
@@ -708,6 +841,7 @@ static const struct bd718xx_regulator_data bd71837_regulators[] = {
 			.enable_reg = BD71837_REG_BUCK3_CTRL,
 			.enable_mask = BD718XX_BUCK_EN,
 			.owner = THIS_MODULE,
+			.of_parse_cb = buck3_set_hw_dvs_levels,
 		},
 		.init = {
 			.reg = BD71837_REG_BUCK3_CTRL,
@@ -731,6 +865,7 @@ static const struct bd718xx_regulator_data bd71837_regulators[] = {
 			.enable_reg = BD71837_REG_BUCK4_CTRL,
 			.enable_mask = BD718XX_BUCK_EN,
 			.owner = THIS_MODULE,
+			.of_parse_cb = buck4_set_hw_dvs_levels,
 		},
 		.init = {
 			.reg = BD71837_REG_BUCK4_CTRL,
@@ -1029,6 +1164,7 @@ static int bd718xx_probe(struct platform_device *pdev)
 	};
 
 	int i, j, err;
+	bool use_snvs;
 
 	mfd = dev_get_drvdata(pdev->dev.parent);
 	if (!mfd) {
@@ -1055,27 +1191,28 @@ static int bd718xx_probe(struct platform_device *pdev)
 			BD718XX_REG_REGLOCK);
 	}
 
-	/* At poweroff transition PMIC HW disables EN bit for regulators but
-	 * leaves SEL bit untouched. So if state transition from POWEROFF
-	 * is done to SNVS - then all power rails controlled by SW (having
-	 * SEL bit set) stay disabled as EN is cleared. This may result boot
-	 * failure if any crucial systems are powered by these rails.
-	 *
+	use_snvs = of_property_read_bool(pdev->dev.parent->of_node,
+					 "rohm,reset-snvs-powered");
+
+	/*
 	 * Change the next stage from poweroff to be READY instead of SNVS
 	 * for all reset types because OTP loading at READY will clear SEL
 	 * bit allowing HW defaults for power rails to be used
 	 */
-	err = regmap_update_bits(mfd->regmap, BD718XX_REG_TRANS_COND1,
-				 BD718XX_ON_REQ_POWEROFF_MASK |
-				 BD718XX_SWRESET_POWEROFF_MASK |
-				 BD718XX_WDOG_POWEROFF_MASK |
-				 BD718XX_KEY_L_POWEROFF_MASK,
-				 BD718XX_POWOFF_TO_RDY);
-	if (err) {
-		dev_err(&pdev->dev, "Failed to change reset target\n");
-		goto err;
-	} else {
-		dev_dbg(&pdev->dev, "Changed all resets from SVNS to READY\n");
+	if (!use_snvs) {
+		err = regmap_update_bits(mfd->regmap, BD718XX_REG_TRANS_COND1,
+					 BD718XX_ON_REQ_POWEROFF_MASK |
+					 BD718XX_SWRESET_POWEROFF_MASK |
+					 BD718XX_WDOG_POWEROFF_MASK |
+					 BD718XX_KEY_L_POWEROFF_MASK,
+					 BD718XX_POWOFF_TO_RDY);
+		if (err) {
+			dev_err(&pdev->dev, "Failed to change reset target\n");
+			goto err;
+		} else {
+			dev_dbg(&pdev->dev,
+				"Changed all resets from SVNS to READY\n");
+		}
 	}
 
 	for (i = 0; i < pmic_regulators[mfd->chip_type].r_amount; i++) {
@@ -1098,19 +1235,33 @@ static int bd718xx_probe(struct platform_device *pdev)
 			err = PTR_ERR(rdev);
 			goto err;
 		}
-		/* Regulator register gets the regulator constraints and
+
+		/*
+		 * Regulator register gets the regulator constraints and
 		 * applies them (set_machine_constraints). This should have
 		 * turned the control register(s) to correct values and we
 		 * can now switch the control from PMIC state machine to the
 		 * register interface
+		 *
+		 * At poweroff transition PMIC HW disables EN bit for
+		 * regulators but leaves SEL bit untouched. So if state
+		 * transition from POWEROFF is done to SNVS - then all power
+		 * rails controlled by SW (having SEL bit set) stay disabled
+		 * as EN is cleared. This will result boot failure if any
+		 * crucial systems are powered by these rails. We don't
+		 * enable SW control for crucial regulators if snvs state is
+		 * used
 		 */
-		err = regmap_update_bits(mfd->regmap, r->init.reg,
-					 r->init.mask, r->init.val);
-		if (err) {
-			dev_err(&pdev->dev,
-				"Failed to write BUCK/LDO SEL bit for (%s)\n",
-				desc->name);
-			goto err;
+		if (!use_snvs || !rdev->constraints->always_on ||
+		    !rdev->constraints->boot_on) {
+			err = regmap_update_bits(mfd->regmap, r->init.reg,
+						 r->init.mask, r->init.val);
+			if (err) {
+				dev_err(&pdev->dev,
+					"Failed to take control for (%s)\n",
+					desc->name);
+				goto err;
+			}
 		}
 		for (j = 0; j < r->additional_init_amnt; j++) {
 			err = regmap_update_bits(mfd->regmap,