regulator: Introduce Qualcomm REFGEN regulator driver

Modern Qualcomm SoCs have a REFGEN (reference voltage generator)
regulator, providing reference voltage to on-chip IP, like PHYs.

Add a driver to support toggling that regulator.
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20230628-topic-refgen-v3-2-9fbf0e605d23@linaro.orgSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/Kconfig

@@ -989,6 +989,17 @@ config REGULATOR_PWM
 	  This driver supports PWM controlled voltage regulators. PWM
 	  duty cycle can increase or decrease the voltage.
 
+config REGULATOR_QCOM_REFGEN
+	tristate "Qualcomm REFGEN regulator driver"
+	depends on HAS_IOMEM
+	depends on REGMAP
+	help
+	  This driver supports the MMIO-mapped reference voltage regulator,
+	  used internally by some PHYs on many Qualcomm SoCs.
+
+	  Say M here if you want to include support for this regulator as
+	  a module. The module will be named "qcom-refgen-regulator".
+
 config REGULATOR_QCOM_RPM
 	tristate "Qualcomm RPM regulator driver"
 	depends on MFD_QCOM_RPM

drivers/regulator/Makefile

@@ -108,6 +108,7 @@ obj-$(CONFIG_REGULATOR_MT6380)	+= mt6380-regulator.o
 obj-$(CONFIG_REGULATOR_MT6397)	+= mt6397-regulator.o
 obj-$(CONFIG_REGULATOR_MTK_DVFSRC) += mtk-dvfsrc-regulator.o
 obj-$(CONFIG_REGULATOR_QCOM_LABIBB) += qcom-labibb-regulator.o
+obj-$(CONFIG_REGULATOR_QCOM_REFGEN) += qcom-refgen-regulator.o
 obj-$(CONFIG_REGULATOR_QCOM_RPM) += qcom_rpm-regulator.o
 obj-$(CONFIG_REGULATOR_QCOM_RPMH) += qcom-rpmh-regulator.o
 obj-$(CONFIG_REGULATOR_QCOM_SMD_RPM) += qcom_smd-regulator.o

drivers/regulator/qcom-refgen-regulator.c

+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (c) 2017, 2019-2020, The Linux Foundation. All rights reserved.
+// Copyright (c) 2023, Linaro Limited
+
+#include <linux/bitfield.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+#include <linux/regulator/of_regulator.h>
+
+#define REFGEN_REG_BIAS_EN		0x08
+#define REFGEN_BIAS_EN_MASK		GENMASK(2, 0)
+ #define REFGEN_BIAS_EN_ENABLE		0x7
+ #define REFGEN_BIAS_EN_DISABLE		0x6
+
+#define REFGEN_REG_BG_CTRL		0x14
+#define REFGEN_BG_CTRL_MASK		GENMASK(2, 1)
+ #define REFGEN_BG_CTRL_ENABLE		0x3
+ #define REFGEN_BG_CTRL_DISABLE		0x2
+
+#define REFGEN_REG_PWRDWN_CTRL5		0x80
+#define REFGEN_PWRDWN_CTRL5_MASK	BIT(0)
+ #define REFGEN_PWRDWN_CTRL5_ENABLE	0x1
+
+static int qcom_sdm845_refgen_enable(struct regulator_dev *rdev)
+{
+	regmap_update_bits(rdev->regmap, REFGEN_REG_BG_CTRL, REFGEN_BG_CTRL_MASK,
+			   FIELD_PREP(REFGEN_BG_CTRL_MASK, REFGEN_BG_CTRL_ENABLE));
+
+	regmap_write(rdev->regmap, REFGEN_REG_BIAS_EN,
+		     FIELD_PREP(REFGEN_BIAS_EN_MASK, REFGEN_BIAS_EN_ENABLE));
+
+	return 0;
+}
+
+static int qcom_sdm845_refgen_disable(struct regulator_dev *rdev)
+{
+	regmap_write(rdev->regmap, REFGEN_REG_BIAS_EN,
+		     FIELD_PREP(REFGEN_BIAS_EN_MASK, REFGEN_BIAS_EN_DISABLE));
+
+	regmap_update_bits(rdev->regmap, REFGEN_REG_BG_CTRL, REFGEN_BG_CTRL_MASK,
+			   FIELD_PREP(REFGEN_BG_CTRL_MASK, REFGEN_BG_CTRL_DISABLE));
+
+	return 0;
+}
+
+static int qcom_sdm845_refgen_is_enabled(struct regulator_dev *rdev)
+{
+	u32 val;
+
+	regmap_read(rdev->regmap, REFGEN_REG_BG_CTRL, &val);
+	if (FIELD_GET(REFGEN_BG_CTRL_MASK, val) != REFGEN_BG_CTRL_ENABLE)
+		return 0;
+
+	regmap_read(rdev->regmap, REFGEN_REG_BIAS_EN, &val);
+	if (FIELD_GET(REFGEN_BIAS_EN_MASK, val) != REFGEN_BIAS_EN_ENABLE)
+		return 0;
+
+	return 1;
+}
+
+static struct regulator_desc sdm845_refgen_desc = {
+	.enable_time = 5,
+	.name = "refgen",
+	.owner = THIS_MODULE,
+	.type = REGULATOR_VOLTAGE,
+	.ops = &(const struct regulator_ops) {
+		.enable		= qcom_sdm845_refgen_enable,
+		.disable	= qcom_sdm845_refgen_disable,
+		.is_enabled	= qcom_sdm845_refgen_is_enabled,
+	},
+};
+
+static struct regulator_desc sm8250_refgen_desc = {
+	.enable_reg = REFGEN_REG_PWRDWN_CTRL5,
+	.enable_mask = REFGEN_PWRDWN_CTRL5_MASK,
+	.enable_val = REFGEN_PWRDWN_CTRL5_ENABLE,
+	.disable_val = 0,
+	.enable_time = 5,
+	.name = "refgen",
+	.owner = THIS_MODULE,
+	.type = REGULATOR_VOLTAGE,
+	.ops = &(const struct regulator_ops) {
+		.enable		= regulator_enable_regmap,
+		.disable	= regulator_disable_regmap,
+		.is_enabled	= regulator_is_enabled_regmap,
+	},
+};
+
+static const struct regmap_config qcom_refgen_regmap_config = {
+	.reg_bits = 32,
+	.reg_stride = 4,
+	.val_bits = 32,
+	.fast_io = true,
+};
+
+static int qcom_refgen_probe(struct platform_device *pdev)
+{
+	struct regulator_init_data *init_data;
+	struct regulator_config config = {};
+	const struct regulator_desc *rdesc;
+	struct device *dev = &pdev->dev;
+	struct regulator_dev *rdev;
+	struct regmap *regmap;
+	void __iomem *base;
+
+	rdesc = of_device_get_match_data(dev);
+	if (!rdesc)
+		return -ENODATA;
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	regmap = devm_regmap_init_mmio(dev, base, &qcom_refgen_regmap_config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	init_data = of_get_regulator_init_data(dev, dev->of_node, rdesc);
+	if (!init_data)
+		return -ENOMEM;
+
+	config.dev = dev;
+	config.init_data = init_data;
+	config.of_node = dev->of_node;
+	config.regmap = regmap;
+
+	rdev = devm_regulator_register(dev, rdesc, &config);
+	if (IS_ERR(rdev))
+		return PTR_ERR(rdev);
+
+	return 0;
+}
+
+static const struct of_device_id qcom_refgen_match_table[] = {
+	{ .compatible = "qcom,sdm845-refgen-regulator", .data = &sdm845_refgen_desc },
+	{ .compatible = "qcom,sm8250-refgen-regulator", .data = &sm8250_refgen_desc },
+	{ }
+};
+
+static struct platform_driver qcom_refgen_driver = {
+	.probe = qcom_refgen_probe,
+	.driver = {
+		.name = "qcom-refgen-regulator",
+		.of_match_table = qcom_refgen_match_table,
+	},
+};
+module_platform_driver(qcom_refgen_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Qualcomm REFGEN regulator driver");