[RFC 4/5] regulator: bq257xx: Add bq257xx boost regulator driver

[Chris Morgan <macroalpha82@gmail.com>]

From: Chris Morgan <macromorgan@hotmail.com>

Add support for the boost regulator found in the Texas Instruments
BQ25703. The boost regulator is capable of outputting between 4.48
and 20.8 volts and between 0 and 6.35 amps.

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
---
 drivers/regulator/Kconfig             |   8 ++
 drivers/regulator/Makefile            |   1 +
 drivers/regulator/bq257xx-regulator.c | 195 ++++++++++++++++++++++++++
 3 files changed, 204 insertions(+)
 create mode 100644 drivers/regulator/bq257xx-regulator.c

diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 4b411a09c1a6..db432e3fb37e 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -286,6 +286,14 @@ config REGULATOR_BD96801
 	  This driver can also be built as a module. If so, the module
 	  will be called bd96801-regulator.
 
+config REGULATOR_BQ257XX
+	tristate "TI BQ257XX regulator family"
+	depends on MFD_BQ257XX
+	depends on GPIOLIB || COMPILE_TEST
+	help
+	  Say Y to enable support for the boost regulator function of
+	  the BQ257XX family of charger circuits.
+
 config REGULATOR_CPCAP
 	tristate "Motorola CPCAP regulator"
 	depends on MFD_CPCAP
diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
index a61fa42b13c4..6e8cdb0f554f 100644
--- a/drivers/regulator/Makefile
+++ b/drivers/regulator/Makefile
@@ -37,6 +37,7 @@ obj-$(CONFIG_REGULATOR_BD71828) += bd71828-regulator.o
 obj-$(CONFIG_REGULATOR_BD718XX) += bd718x7-regulator.o
 obj-$(CONFIG_REGULATOR_BD9571MWV) += bd9571mwv-regulator.o
 obj-$(CONFIG_REGULATOR_BD957XMUF) += bd9576-regulator.o
+obj-$(CONFIG_REGULATOR_BQ257XX) += bq257xx-regulator.o
 obj-$(CONFIG_REGULATOR_DA903X)	+= da903x-regulator.o
 obj-$(CONFIG_REGULATOR_BD96801) += bd96801-regulator.o
 obj-$(CONFIG_REGULATOR_DA9052)	+= da9052-regulator.o
diff --git a/drivers/regulator/bq257xx-regulator.c b/drivers/regulator/bq257xx-regulator.c
new file mode 100644
index 000000000000..9246b091288c
--- /dev/null
+++ b/drivers/regulator/bq257xx-regulator.c
@@ -0,0 +1,195 @@
+// SPDX-License-Identifier: GPL-2.0
+/* BQ257XX Battery Charger Driver
+ * Copyright (C) 2024 Chris Morgan <macromorgan@hotmail.com>
+ * Based off of BQ256XX Battery Charger driver and
+ * RK808 Regulator driver.
+ */
+
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/mfd/bq257xx.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/of_regulator.h>
+
+struct bq257xx_reg_data {
+	struct bq257xx_device *bq;
+	struct regulator_dev *bq257xx_reg;
+	struct gpio_desc *otg_en_gpio;
+	struct regulator_desc desc;
+};
+
+static int bq25703_vbus_get_cur_limit(struct regulator_dev *rdev)
+{
+	struct bq257xx_reg_data *pdata = rdev_get_drvdata(rdev);
+	int ret;
+	unsigned int reg;
+
+	ret = regmap_read(pdata->bq->regmap, BQ25703_OTG_CURRENT, &reg);
+	if (ret)
+		return ret;
+	return FIELD_GET(BQ25703_OTG_CUR_MASK, reg) * BQ25703_OTG_CUR_STEP_UA;
+}
+
+/*
+ * Check if the minimum current and maximum current requested are
+ * sane values, then set the register accordingly.
+ */
+static int bq25703_vbus_set_cur_limit(struct regulator_dev *rdev,
+				      int min_uA, int max_uA)
+{
+	struct bq257xx_reg_data *pdata = rdev_get_drvdata(rdev);
+	unsigned int reg;
+
+	if ((min_uA > BQ25703_OTG_CUR_MAX_UA) || (max_uA < 0))
+		return -EINVAL;
+
+	reg = (max_uA / BQ25703_OTG_CUR_STEP_UA);
+
+	/* Catch rounding errors since our step is 50000uA. */
+	if ((reg * BQ25703_OTG_CUR_STEP_UA) < min_uA)
+		return -EINVAL;
+
+	return regmap_write(pdata->bq->regmap, BQ25703_OTG_CURRENT,
+			    FIELD_PREP(BQ25703_OTG_CUR_MASK, reg));
+}
+
+static int bq25703_vbus_enable(struct regulator_dev *rdev)
+{
+	struct bq257xx_reg_data *pdata = rdev_get_drvdata(rdev);
+
+	if (pdata->otg_en_gpio)
+		gpiod_set_value_cansleep(pdata->otg_en_gpio, 1);
+	return regulator_enable_regmap(rdev);
+}
+
+static int bq25703_vbus_disable(struct regulator_dev *rdev)
+{
+	struct bq257xx_reg_data *pdata = rdev_get_drvdata(rdev);
+
+	if (pdata->otg_en_gpio)
+		gpiod_set_value_cansleep(pdata->otg_en_gpio, 0);
+	return regulator_disable_regmap(rdev);
+}
+
+static const struct regulator_ops bq25703_vbus_ops = {
+	.enable = bq25703_vbus_enable,
+	.disable = bq25703_vbus_disable,
+	.is_enabled = regulator_is_enabled_regmap,
+	.list_voltage = regulator_list_voltage_linear,
+	.get_voltage_sel = regulator_get_voltage_sel_regmap,
+	.set_voltage_sel = regulator_set_voltage_sel_regmap,
+	.get_current_limit = bq25703_vbus_get_cur_limit,
+	.set_current_limit = bq25703_vbus_set_cur_limit,
+};
+
+static const struct regulator_desc bq25703_vbus_desc = {
+	.name = "usb_otg_vbus",
+	.of_match = of_match_ptr("usb-otg-vbus"),
+	.regulators_node = of_match_ptr("regulators"),
+	.type = REGULATOR_VOLTAGE,
+	.owner = THIS_MODULE,
+	.ops = &bq25703_vbus_ops,
+	.min_uV = BQ25703_OTG_VOLT_MIN_UV,
+	.uV_step = BQ25703_OTG_VOLT_STEP_UV,
+	.n_voltages = BQ25703_OTG_VOLT_NUM_VOLT,
+	.enable_mask = BQ25703_EN_OTG_MASK,
+	.enable_reg = BQ25703_CHARGE_OPTION_3,
+	.enable_val = BQ25703_EN_OTG_MASK,
+	.disable_val = 0,
+	.vsel_reg = BQ25703_OTG_VOLT,
+	.vsel_mask = BQ25703_OTG_VOLT_MASK,
+};
+
+/* Get optional GPIO for OTG regulator enable. */
+static void bq257xx_reg_dt_parse_gpio(struct platform_device *pdev)
+{
+	struct device_node *child, *subchild;
+	struct bq257xx_reg_data *pdata = platform_get_drvdata(pdev);
+
+	child = of_get_child_by_name(pdev->dev.of_node,
+				     pdata->desc.regulators_node);
+	if (!child)
+		return;
+
+	subchild = of_get_child_by_name(child, pdata->desc.of_match);
+	if (!subchild)
+		return;
+
+	of_node_put(child);
+
+	pdata->otg_en_gpio = devm_fwnode_gpiod_get_index(&pdev->dev,
+							 of_fwnode_handle(subchild),
+							 "enable", 0,
+							 GPIOD_OUT_LOW,
+							 pdata->desc.of_match);
+
+	of_node_put(subchild);
+
+	if (IS_ERR_OR_NULL(pdata->otg_en_gpio)) {
+		dev_err(&pdev->dev, "Error getting enable gpio: %ld\n",
+			PTR_ERR(pdata->otg_en_gpio));
+	}
+}
+
+static int bq257xx_regulator_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct bq257xx_device *bq = dev_get_drvdata(pdev->dev.parent);
+	struct bq257xx_reg_data *pdata;
+	struct device_node *np = dev->of_node;
+	struct regulator_init_data *init_data;
+	struct regulator_config cfg = {};
+	int ret;
+
+	pdev->dev.of_node = pdev->dev.parent->of_node;
+	pdev->dev.of_node_reused = true;
+
+	pdata = devm_kzalloc(&pdev->dev, sizeof(struct bq257xx_reg_data), GFP_KERNEL);
+	if (!pdata)
+		return -ENOMEM;
+
+	pdata->bq = bq;
+
+	switch (pdata->bq->variant) {
+	case BQ25703A:
+		pdata->desc = bq25703_vbus_desc;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	platform_set_drvdata(pdev, pdata);
+	bq257xx_reg_dt_parse_gpio(pdev);
+
+	cfg.dev = &pdev->dev;
+	cfg.init_data = init_data;
+	cfg.driver_data = pdata;
+	cfg.of_node = np;
+	cfg.regmap = dev_get_regmap(pdev->dev.parent, NULL);
+	if (!cfg.regmap)
+		return -ENODEV;
+
+	pdata->bq257xx_reg = devm_regulator_register(dev, &pdata->desc, &cfg);
+	if (IS_ERR(pdata->bq257xx_reg)) {
+		return dev_err_probe(&pdev->dev, PTR_ERR(pdata->bq257xx_reg),
+				     "error registering bq257xx regulator");
+	}
+
+	return ret;
+}
+
+static struct platform_driver bq257xx_reg_driver = {
+	.driver = {
+		.name = "bq257xx-regulator",
+	},
+	.probe = bq257xx_regulator_probe,
+};
+
+module_platform_driver(bq257xx_reg_driver);
+
+MODULE_DESCRIPTION("bq257xx regulator driver");
+MODULE_AUTHOR("Chris Morgan <macromorgan@hotmail.com>");
+MODULE_LICENSE("GPL");
-- 
2.34.1