power: regulator: add pwm regulator

add driver support for pwm regulator.

Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Acked-by: Simon Glass <sjg@chromium.org>

drivers/power/regulator/Kconfig

@@ -42,6 +42,16 @@ config DM_REGULATOR_PFUZE100
 	features for REGULATOR PFUZE100. The driver implements get/set api for:
 	value, enable and mode.
 
+config REGULATOR_PWM
+	bool "Enable driver for PWM regulators"
+	depends on DM_REGULATOR
+	---help---
+	Enable support for the PWM regulator functions which voltage are
+	controlled by PWM duty ratio. Some of Rockchip board using this kind
+	of regulator. The driver implements get/set api for the various BUCKS.
+	This driver is controlled by a device tree node
+	which includes voltage limits.
+
 config DM_REGULATOR_MAX77686
 	bool "Enable Driver Model for REGULATOR MAX77686"
 	depends on DM_REGULATOR && DM_PMIC_MAX77686

drivers/power/regulator/Makefile

@@ -9,6 +9,7 @@ obj-$(CONFIG_$(SPL_)DM_REGULATOR) += regulator-uclass.o
 obj-$(CONFIG_REGULATOR_ACT8846) += act8846.o
 obj-$(CONFIG_DM_REGULATOR_MAX77686) += max77686.o
 obj-$(CONFIG_DM_REGULATOR_PFUZE100) += pfuze100.o
+obj-$(CONFIG_REGULATOR_PWM) += pwm_regulator.o
 obj-$(CONFIG_$(SPL_)DM_REGULATOR_FIXED) += fixed.o
 obj-$(CONFIG_REGULATOR_RK808) += rk808.o
 obj-$(CONFIG_REGULATOR_S5M8767) += s5m8767.o

drivers/power/regulator/pwm_regulator.c

+/*
+ * Copyright (C) 2016 Rockchip Electronics Co., Ltd
+ *
+ * Based on kernel drivers/regulator/pwm-regulator.c
+ * Copyright (C) 2014 - STMicroelectronics Inc.
+ * Author: Lee Jones <lee.jones@linaro.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <pwm.h>
+#include <power/regulator.h>
+#include <libfdt.h>
+#include <fdt_support.h>
+#include <fdtdec.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct pwm_regulator_info {
+	/* pwm id corresponding to the PWM driver */
+	int pwm_id;
+	/* the period of one PWM cycle */
+	int period_ns;
+	struct udevice *pwm;
+	/* initialize voltage of regulator */
+	unsigned int init_voltage;
+	/* the maximum voltage of regulator */
+	unsigned int max_voltage;
+	/* the minimum voltage of regulator */
+	unsigned int min_voltage;
+	/* the current voltage of regulator */
+	unsigned int volt_uV;
+};
+
+static int pwm_regulator_enable(struct udevice *dev, bool enable)
+{
+	struct pwm_regulator_info *priv = dev_get_priv(dev);
+
+	return pwm_set_enable(priv->pwm, priv->pwm_id, enable);
+}
+
+static int pwm_voltage_to_duty_cycle_percentage(struct udevice *dev, int req_uV)
+{
+	struct pwm_regulator_info *priv = dev_get_priv(dev);
+	int min_uV = priv->min_voltage;
+	int max_uV = priv->max_voltage;
+	int diff = max_uV - min_uV;
+
+	return 100 - (((req_uV * 100) - (min_uV * 100)) / diff);
+}
+
+static int pwm_regulator_get_voltage(struct udevice *dev)
+{
+	struct pwm_regulator_info *priv = dev_get_priv(dev);
+
+	return priv->volt_uV;
+}
+
+static int pwm_regulator_set_voltage(struct udevice *dev, int uvolt)
+{
+	struct pwm_regulator_info *priv = dev_get_priv(dev);
+	int duty_cycle;
+	int ret = 0;
+
+	duty_cycle = pwm_voltage_to_duty_cycle_percentage(dev, uvolt);
+
+	ret = pwm_set_config(priv->pwm, priv->pwm_id,
+			(priv->period_ns / 100) * duty_cycle, priv->period_ns);
+	if (ret) {
+		dev_err(dev, "Failed to configure PWM\n");
+		return ret;
+	}
+
+	ret = pwm_set_enable(priv->pwm, priv->pwm_id, true);
+	if (ret) {
+		dev_err(dev, "Failed to enable PWM\n");
+		return ret;
+	}
+	priv->volt_uV = uvolt;
+	return ret;
+}
+
+static int pwm_regulator_ofdata_to_platdata(struct udevice *dev)
+{
+	struct pwm_regulator_info *priv = dev_get_priv(dev);
+	struct fdtdec_phandle_args args;
+	const void *blob = gd->fdt_blob;
+	int node = dev->of_offset;
+	int ret;
+
+	ret = fdtdec_parse_phandle_with_args(blob, node, "pwms", "#pwm-cells",
+					     0, 0, &args);
+	if (ret) {
+		debug("%s: Cannot get PWM phandle: ret=%d\n", __func__, ret);
+		return ret;
+	}
+	/* TODO: pwm_id here from device tree if needed */
+
+	priv->period_ns = args.args[1];
+
+	priv->init_voltage = fdtdec_get_int(blob, node,
+			"regulator-init-microvolt", -1);
+	if (priv->init_voltage < 0) {
+		printf("Cannot find regulator pwm init_voltage\n");
+		return -EINVAL;
+	}
+
+	ret = uclass_get_device_by_of_offset(UCLASS_PWM, args.node, &priv->pwm);
+	if (ret) {
+		debug("%s: Cannot get PWM: ret=%d\n", __func__, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int pwm_regulator_probe(struct udevice *dev)
+{
+	struct pwm_regulator_info *priv = dev_get_priv(dev);
+	struct dm_regulator_uclass_platdata *uc_pdata;
+
+	uc_pdata = dev_get_uclass_platdata(dev);
+
+	uc_pdata->type = REGULATOR_TYPE_BUCK;
+	uc_pdata->mode_count = 0;
+	priv->max_voltage = uc_pdata->max_uV;
+	priv->min_voltage = uc_pdata->min_uV;
+
+	if (priv->init_voltage)
+		pwm_regulator_set_voltage(dev, priv->init_voltage);
+
+	pwm_regulator_enable(dev, 1);
+
+	return 0;
+}
+
+static const struct dm_regulator_ops pwm_regulator_ops = {
+	.get_value  = pwm_regulator_get_voltage,
+	.set_value  = pwm_regulator_set_voltage,
+	.set_enable = pwm_regulator_enable,
+};
+
+static const struct udevice_id pwm_regulator_ids[] = {
+	{ .compatible = "pwm-regulator" },
+	{ }
+};
+
+U_BOOT_DRIVER(pwm_regulator) = {
+	.name = "pwm_regulator",
+	.id = UCLASS_REGULATOR,
+	.ops = &pwm_regulator_ops,
+	.probe = pwm_regulator_probe,
+	.of_match = pwm_regulator_ids,
+	.ofdata_to_platdata	= pwm_regulator_ofdata_to_platdata,
+	.priv_auto_alloc_size	= sizeof(struct pwm_regulator_info),
+};