[PATCH v3 0/2] regulator: get voltage & duty table from dts for st-pwm

[PATCH v3 0/2] regulator: get voltage & duty table from dts for st-pwm

[Chris Zhong]

get voltage & duty table from device tree might be better, other platforms can also use this
driver without any modify.
Tested on a rk3288 sdk board as logic voltage regulator.

Changes in v3:
Adviced by Doug Anderson
- Make Kconfig & Makefile alphabetical
- remove pwm_reg_period from pwm_regulator_data
- modify the calculation in pwm_regulator_set_voltage_sel
- add length validity check
Adviced by Doug Anderson
- update the Example

Changes in v2:
Adviced by Lee Jones
- rename the file
- remove all the prefix st_
- add depend on PWM in Kconfig
Adviced by Lee Jones
- rename the documentation
Adviced by Doug Anderson
- update the example
Adviced by Mark Rutland
- remove pwm-reg-period

Chris Zhong (2):
  regulator: st-pwm: get voltage and duty table from dts
  dt-bindings: add devicetree bindings for st-pwm regulator

 .../bindings/regulator/pwm-regulator.txt           |   29 +++
 drivers/regulator/Kconfig                          |   13 +-
 drivers/regulator/Makefile                         |    2 +-
 drivers/regulator/pwm-regulator.c                  |  197 ++++++++++++++++++++
 drivers/regulator/st-pwm.c                         |  190 -------------------
 5 files changed, 234 insertions(+), 197 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/regulator/pwm-regulator.txt
 create mode 100644 drivers/regulator/pwm-regulator.c
 delete mode 100644 drivers/regulator/st-pwm.c

-- 
1.7.9.5

[PATCH v3 1/2] regulator: st-pwm: get voltage and duty table from dts

[Chris Zhong]

Get voltage & duty table from device tree might be better, other platforms can also use this
driver without any modify.

Signed-off-by: Chris Zhong <zyw@rock-chips.com>

---

Changes in v3:
Adviced by Doug Anderson
- Make Kconfig & Makefile alphabetical
- remove pwm_reg_period from pwm_regulator_data
- modify the calculation in pwm_regulator_set_voltage_sel
- add length validity check

Changes in v2:
Adviced by Lee Jones
- rename the file
- remove all the prefix st_
- add depend on PWM in Kconfig

 drivers/regulator/Kconfig         |   13 +--
 drivers/regulator/Makefile        |    2 +-
 drivers/regulator/pwm-regulator.c |  197 +++++++++++++++++++++++++++++++++++++
 drivers/regulator/st-pwm.c        |  190 -----------------------------------
 4 files changed, 205 insertions(+), 197 deletions(-)
 create mode 100644 drivers/regulator/pwm-regulator.c
 delete mode 100644 drivers/regulator/st-pwm.c

diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index fb32bab..320751a 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -449,6 +449,13 @@ config REGULATOR_PFUZE100
 	  Say y here to support the regulators found on the Freescale
 	  PFUZE100/PFUZE200 PMIC.
 
+config REGULATOR_PWM
+	tristate "PWM voltage regulator"
+	depends on PWM
+	help
+	  This driver supports PWM controlled voltage regulators. Config PWM
+	  duty can increasing or decreasing the voltage.
+
 config REGULATOR_RC5T583
 	tristate "RICOH RC5T583 Power regulators"
 	depends on MFD_RC5T583
@@ -493,12 +500,6 @@ config REGULATOR_S5M8767
 	 via I2C bus. S5M8767A have 9 Bucks and 28 LDOs output and
 	 supports DVS mode with 8bits of output voltage control.
 
-config REGULATOR_ST_PWM
-	tristate "STMicroelectronics PWM voltage regulator"
-	depends on ARCH_STI
-	help
-	 This driver supports ST's PWM controlled voltage regulators.
-
 config REGULATOR_TI_ABB
 	tristate "TI Adaptive Body Bias on-chip LDO"
 	depends on ARCH_OMAP
diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
index 236fdbb..f3cf5a5 100644
--- a/drivers/regulator/Makefile
+++ b/drivers/regulator/Makefile
@@ -57,6 +57,7 @@ obj-$(CONFIG_REGULATOR_MC13892) += mc13892-regulator.o
 obj-$(CONFIG_REGULATOR_MC13XXX_CORE) +=  mc13xxx-regulator-core.o
 obj-$(CONFIG_REGULATOR_PALMAS) += palmas-regulator.o
 obj-$(CONFIG_REGULATOR_PFUZE100) += pfuze100-regulator.o
+obj-$(CONFIG_REGULATOR_PWM) += pwm-regulator.o
 obj-$(CONFIG_REGULATOR_TPS51632) += tps51632-regulator.o
 obj-$(CONFIG_REGULATOR_PBIAS) += pbias-regulator.o
 obj-$(CONFIG_REGULATOR_PCAP) += pcap-regulator.o
@@ -66,7 +67,6 @@ obj-$(CONFIG_REGULATOR_RK808)   += rk808-regulator.o
 obj-$(CONFIG_REGULATOR_S2MPA01) += s2mpa01.o
 obj-$(CONFIG_REGULATOR_S2MPS11) += s2mps11.o
 obj-$(CONFIG_REGULATOR_S5M8767) += s5m8767.o
-obj-$(CONFIG_REGULATOR_ST_PWM) += st-pwm.o
 obj-$(CONFIG_REGULATOR_STW481X_VMMC) += stw481x-vmmc.o
 obj-$(CONFIG_REGULATOR_TI_ABB) += ti-abb-regulator.o
 obj-$(CONFIG_REGULATOR_TPS6105X) += tps6105x-regulator.o
diff --git a/drivers/regulator/pwm-regulator.c b/drivers/regulator/pwm-regulator.c
new file mode 100644
index 0000000..97af94e
--- /dev/null
+++ b/drivers/regulator/pwm-regulator.c
@@ -0,0 +1,197 @@
+/*
+ * Regulator driver for PWM Regulators
+ *
+ * Copyright (C) 2014 - STMicroelectronics Inc.
+ *
+ * Author: Lee Jones <lee.jones@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+#include <linux/regulator/of_regulator.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/pwm.h>
+
+struct pwm_regulator_data {
+	struct regulator_desc desc;
+	struct pwm_voltages *duty_cycle_table;
+	struct pwm_device *pwm;
+	bool enabled;
+	int state;
+};
+
+struct pwm_voltages {
+	unsigned int uV;
+	unsigned int dutycycle;
+};
+
+static int pwm_regulator_get_voltage_sel(struct regulator_dev *dev)
+{
+	struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
+
+	return drvdata->state;
+}
+
+static int pwm_regulator_set_voltage_sel(struct regulator_dev *dev,
+					 unsigned selector)
+{
+	struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
+	unsigned int pwm_reg_period;
+	int dutycycle;
+	int ret;
+
+	pwm_reg_period = pwm_get_period(drvdata->pwm);
+
+	dutycycle = (pwm_reg_period *
+		    drvdata->duty_cycle_table[selector].dutycycle) / 100;
+
+	ret = pwm_config(drvdata->pwm, dutycycle, pwm_reg_period);
+	if (ret) {
+		dev_err(&dev->dev, "Failed to configure PWM\n");
+		return ret;
+	}
+
+	drvdata->state = selector;
+
+	if (!drvdata->enabled) {
+		ret = pwm_enable(drvdata->pwm);
+		if (ret) {
+			dev_err(&dev->dev, "Failed to enable PWM\n");
+			return ret;
+		}
+		drvdata->enabled = true;
+	}
+
+	return 0;
+}
+
+static int pwm_regulator_list_voltage(struct regulator_dev *dev,
+				      unsigned selector)
+{
+	struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
+
+	if (selector >= drvdata->desc.n_voltages)
+		return -EINVAL;
+
+	return drvdata->duty_cycle_table[selector].uV;
+}
+
+static struct regulator_ops pwm_regulator_voltage_ops = {
+	.set_voltage_sel = pwm_regulator_set_voltage_sel,
+	.get_voltage_sel = pwm_regulator_get_voltage_sel,
+	.list_voltage    = pwm_regulator_list_voltage,
+	.map_voltage     = regulator_map_voltage_iterate,
+};
+
+static struct regulator_desc pwm_regulator_desc = {
+	.name		= "pwm-regulator",
+	.ops		= &pwm_regulator_voltage_ops,
+	.type		= REGULATOR_VOLTAGE,
+	.owner		= THIS_MODULE,
+	.supply_name    = "pwm",
+};
+
+static int pwm_regulator_probe(struct platform_device *pdev)
+{
+	struct pwm_regulator_data *drvdata;
+	struct property *prop;
+	struct regulator_dev *regulator;
+	struct regulator_config config = { };
+	struct device_node *np = pdev->dev.of_node;
+	int length, ret;
+
+	if (!np) {
+		dev_err(&pdev->dev, "Device Tree node missing\n");
+		return -EINVAL;
+	}
+
+	drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
+	if (!drvdata)
+		return -ENOMEM;
+
+	memcpy(&drvdata->desc, &pwm_regulator_desc, sizeof(pwm_regulator_desc));
+
+	/* determine the number of voltage-table */
+	prop = of_find_property(np, "voltage-table", &length);
+	if (!prop) {
+		dev_err(&pdev->dev, "No voltage-table\n");
+		return -EINVAL;
+	}
+
+	if ((length < sizeof(*drvdata->duty_cycle_table)) ||
+	    (length % sizeof(*drvdata->duty_cycle_table))) {
+		dev_err(&pdev->dev, "voltage-table length(%d) is invalid\n",
+			length);
+		return -EINVAL;
+	}
+
+	drvdata->desc.n_voltages = length / sizeof(*drvdata->duty_cycle_table);
+
+	drvdata->duty_cycle_table = devm_kzalloc(&pdev->dev,
+						 length, GFP_KERNEL);
+	if (!drvdata->duty_cycle_table)
+		return -ENOMEM;
+
+	/* read voltage table from DT property */
+	ret = of_property_read_u32_array(np, "voltage-table",
+					 (u32 *)drvdata->duty_cycle_table,
+					 length / sizeof(u32));
+	if (ret < 0) {
+		dev_err(&pdev->dev, "read voltage-table failed\n");
+		return ret;
+	}
+
+	config.init_data = of_get_regulator_init_data(&pdev->dev, np);
+	if (!config.init_data)
+		return -ENOMEM;
+
+	config.of_node = np;
+	config.dev = &pdev->dev;
+	config.driver_data = drvdata;
+
+	drvdata->pwm = devm_pwm_get(&pdev->dev, NULL);
+	if (IS_ERR(drvdata->pwm)) {
+		dev_err(&pdev->dev, "Failed to get PWM\n");
+		return PTR_ERR(drvdata->pwm);
+	}
+
+	regulator = devm_regulator_register(&pdev->dev,
+					    &drvdata->desc, &config);
+	if (IS_ERR(regulator)) {
+		dev_err(&pdev->dev, "Failed to register regulator %s\n",
+			drvdata->desc.name);
+		return PTR_ERR(regulator);
+	}
+
+	return 0;
+}
+
+static const struct of_device_id pwm_of_match[] = {
+	{ .compatible = "pwm-regulator" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, pwm_of_match);
+
+static struct platform_driver pwm_regulator_driver = {
+	.driver = {
+		.name		= "pwm-regulator",
+		.owner		= THIS_MODULE,
+		.of_match_table = of_match_ptr(pwm_of_match),
+	},
+	.probe = pwm_regulator_probe,
+};
+
+module_platform_driver(pwm_regulator_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Lee Jones <lee.jones@linaro.org>");
+MODULE_DESCRIPTION("PWM Regulator Driver");
+MODULE_ALIAS("platform:pwm-regulator");
diff --git a/drivers/regulator/st-pwm.c b/drivers/regulator/st-pwm.c
deleted file mode 100644
index 5ea78df..0000000
--- a/drivers/regulator/st-pwm.c
+++ /dev/null
@@ -1,190 +0,0 @@
-/*
- * Regulator driver for ST's PWM Regulators
- *
- * Copyright (C) 2014 - STMicroelectronics Inc.
- *
- * Author: Lee Jones <lee.jones@linaro.org>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
-
-#include <linux/module.h>
-#include <linux/init.h>
-#include <linux/err.h>
-#include <linux/regulator/driver.h>
-#include <linux/regulator/machine.h>
-#include <linux/regulator/of_regulator.h>
-#include <linux/of.h>
-#include <linux/of_device.h>
-#include <linux/pwm.h>
-
-#define ST_PWM_REG_PERIOD 8448
-
-struct st_pwm_regulator_pdata {
-	const struct regulator_desc *desc;
-	struct st_pwm_voltages *duty_cycle_table;
-};
-
-struct st_pwm_regulator_data {
-	const struct st_pwm_regulator_pdata *pdata;
-	struct pwm_device *pwm;
-	bool enabled;
-	int state;
-};
-
-struct st_pwm_voltages {
-	unsigned int uV;
-	unsigned int dutycycle;
-};
-
-static int st_pwm_regulator_get_voltage_sel(struct regulator_dev *dev)
-{
-	struct st_pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
-
-	return drvdata->state;
-}
-
-static int st_pwm_regulator_set_voltage_sel(struct regulator_dev *dev,
-					    unsigned selector)
-{
-	struct st_pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
-	int dutycycle;
-	int ret;
-
-	dutycycle = (ST_PWM_REG_PERIOD / 100) *
-		drvdata->pdata->duty_cycle_table[selector].dutycycle;
-
-	ret = pwm_config(drvdata->pwm, dutycycle, ST_PWM_REG_PERIOD);
-	if (ret) {
-		dev_err(&dev->dev, "Failed to configure PWM\n");
-		return ret;
-	}
-
-	drvdata->state = selector;
-
-	if (!drvdata->enabled) {
-		ret = pwm_enable(drvdata->pwm);
-		if (ret) {
-			dev_err(&dev->dev, "Failed to enable PWM\n");
-			return ret;
-		}
-		drvdata->enabled = true;
-	}
-
-	return 0;
-}
-
-static int st_pwm_regulator_list_voltage(struct regulator_dev *dev,
-					 unsigned selector)
-{
-	struct st_pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
-
-	if (selector >= dev->desc->n_voltages)
-		return -EINVAL;
-
-	return drvdata->pdata->duty_cycle_table[selector].uV;
-}
-
-static struct regulator_ops st_pwm_regulator_voltage_ops = {
-	.set_voltage_sel = st_pwm_regulator_set_voltage_sel,
-	.get_voltage_sel = st_pwm_regulator_get_voltage_sel,
-	.list_voltage    = st_pwm_regulator_list_voltage,
-	.map_voltage     = regulator_map_voltage_iterate,
-};
-
-static struct st_pwm_voltages b2105_duty_cycle_table[] = {
-	{ .uV = 1114000, .dutycycle = 0,  },
-	{ .uV = 1095000, .dutycycle = 10, },
-	{ .uV = 1076000, .dutycycle = 20, },
-	{ .uV = 1056000, .dutycycle = 30, },
-	{ .uV = 1036000, .dutycycle = 40, },
-	{ .uV = 1016000, .dutycycle = 50, },
-	/* WARNING: Values above 50% duty-cycle cause boot failures. */
-};
-
-static const struct regulator_desc b2105_desc = {
-	.name		= "b2105-pwm-regulator",
-	.ops		= &st_pwm_regulator_voltage_ops,
-	.type		= REGULATOR_VOLTAGE,
-	.owner		= THIS_MODULE,
-	.n_voltages	= ARRAY_SIZE(b2105_duty_cycle_table),
-	.supply_name    = "pwm",
-};
-
-static const struct st_pwm_regulator_pdata b2105_info = {
-	.desc		  = &b2105_desc,
-	.duty_cycle_table = b2105_duty_cycle_table,
-};
-
-static const struct of_device_id st_pwm_of_match[] = {
-	{ .compatible = "st,b2105-pwm-regulator", .data = &b2105_info, },
-	{ },
-};
-MODULE_DEVICE_TABLE(of, st_pwm_of_match);
-
-static int st_pwm_regulator_probe(struct platform_device *pdev)
-{
-	struct st_pwm_regulator_data *drvdata;
-	struct regulator_dev *regulator;
-	struct regulator_config config = { };
-	struct device_node *np = pdev->dev.of_node;
-	const struct of_device_id *of_match;
-
-	if (!np) {
-		dev_err(&pdev->dev, "Device Tree node missing\n");
-		return -EINVAL;
-	}
-
-	drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
-	if (!drvdata)
-		return -ENOMEM;
-
-	of_match = of_match_device(st_pwm_of_match, &pdev->dev);
-	if (!of_match) {
-		dev_err(&pdev->dev, "failed to match of device\n");
-		return -ENODEV;
-	}
-	drvdata->pdata = of_match->data;
-
-	config.init_data = of_get_regulator_init_data(&pdev->dev, np);
-	if (!config.init_data)
-		return -ENOMEM;
-
-	config.of_node = np;
-	config.dev = &pdev->dev;
-	config.driver_data = drvdata;
-
-	drvdata->pwm = devm_pwm_get(&pdev->dev, NULL);
-	if (IS_ERR(drvdata->pwm)) {
-		dev_err(&pdev->dev, "Failed to get PWM\n");
-		return PTR_ERR(drvdata->pwm);
-	}
-
-	regulator = devm_regulator_register(&pdev->dev,
-					    drvdata->pdata->desc, &config);
-	if (IS_ERR(regulator)) {
-		dev_err(&pdev->dev, "Failed to register regulator %s\n",
-			drvdata->pdata->desc->name);
-		return PTR_ERR(regulator);
-	}
-
-	return 0;
-}
-
-static struct platform_driver st_pwm_regulator_driver = {
-	.driver = {
-		.name		= "st-pwm-regulator",
-		.owner		= THIS_MODULE,
-		.of_match_table = of_match_ptr(st_pwm_of_match),
-	},
-	.probe = st_pwm_regulator_probe,
-};
-
-module_platform_driver(st_pwm_regulator_driver);
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Lee Jones <lee.jones@linaro.org>");
-MODULE_DESCRIPTION("ST PWM Regulator Driver");
-MODULE_ALIAS("platform:st_pwm-regulator");
-- 
1.7.9.5

[PATCH v3 2/2] dt-bindings: add devicetree bindings for st-pwm regulator

[Chris Zhong]

Document the st-pwm regulator

Signed-off-by: Chris Zhong <zyw@rock-chips.com>

---

Changes in v3:
Adviced by Doug Anderson
- update the Example

Changes in v2:
Adviced by Lee Jones
- rename the documentation
Adviced by Doug Anderson
- update the example
Adviced by Mark Rutland
- remove pwm-reg-period

 .../bindings/regulator/pwm-regulator.txt           |   29 ++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/regulator/pwm-regulator.txt

diff --git a/Documentation/devicetree/bindings/regulator/pwm-regulator.txt b/Documentation/devicetree/bindings/regulator/pwm-regulator.txt
new file mode 100644
index 0000000..eb46f7b
--- /dev/null
+++ b/Documentation/devicetree/bindings/regulator/pwm-regulator.txt
@@ -0,0 +1,29 @@
+pwm regulator bindings
+
+Required properties:
+- compatible: Should be "pwm-regulator"
+- pwms: OF device-tree PWM specification (see PWM binding pwm.txt)
+- voltage-table: voltage and duty table, include 2 merbers in each set of
+  brackets, first one is voltage(unit: uv), the next is duty(unit: percent)
+
+Any property defined as part of the core regulator binding defined in
+regulator.txt can also be used.
+
+Example:
+	pwm_regulator {
+		compatible = "pwm-regulator;
+		pwms = <&pwm1 0 8448 0>;
+
+		voltage-table = <1114000 0>,
+				<1095000 10>,
+				<1076000 20>,
+				<1056000 30>,
+				<1036000 40>,
+				<1016000 50>;
+
+		regulator-always-on;
+		regulator-boot-on;
+		regulator-min-microvolt = <1016000>;
+		regulator-max-microvolt = <1114000>;
+		regulator-name = "vdd_logic";
+	};
-- 
1.7.9.5

Re: [PATCH v3 1/2] regulator: st-pwm: get voltage and duty table from dts

[Doug Anderson]

Chris,

On Fri, Sep 19, 2014 at 1:02 AM, Chris Zhong <zyw@rock-chips.com> wrote:
> Get voltage & duty table from device tree might be better, other platforms can also use this
> driver without any modify.
>
> Signed-off-by: Chris Zhong <zyw@rock-chips.com>
>
> ---
>
> Changes in v3:
> Adviced by Doug Anderson
> - Make Kconfig & Makefile alphabetical
> - remove pwm_reg_period from pwm_regulator_data
> - modify the calculation in pwm_regulator_set_voltage_sel
> - add length validity check
>
> Changes in v2:
> Adviced by Lee Jones
> - rename the file
> - remove all the prefix st_
> - add depend on PWM in Kconfig
>
>  drivers/regulator/Kconfig         |   13 +--
>  drivers/regulator/Makefile        |    2 +-
>  drivers/regulator/pwm-regulator.c |  197 +++++++++++++++++++++++++++++++++++++
>  drivers/regulator/st-pwm.c        |  190 -----------------------------------
>  4 files changed, 205 insertions(+), 197 deletions(-)
>  create mode 100644 drivers/regulator/pwm-regulator.c
>  delete mode 100644 drivers/regulator/st-pwm.c
>
> diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
> index fb32bab..320751a 100644
> --- a/drivers/regulator/Kconfig
> +++ b/drivers/regulator/Kconfig
> @@ -449,6 +449,13 @@ config REGULATOR_PFUZE100
>           Say y here to support the regulators found on the Freescale
>           PFUZE100/PFUZE200 PMIC.
>
> +config REGULATOR_PWM
> +       tristate "PWM voltage regulator"
> +       depends on PWM
> +       help
> +         This driver supports PWM controlled voltage regulators. Config PWM
> +         duty can increasing or decreasing the voltage.

Slightly more proper English:
        This driver supports PWM controlled voltage regulators. PWM
        duty cycle can increase or decrease the voltage.


> +static struct regulator_desc pwm_regulator_desc = {
> +       .name           = "pwm-regulator",
> +       .ops            = &pwm_regulator_voltage_ops,
> +       .type           = REGULATOR_VOLTAGE,
> +       .owner          = THIS_MODULE,
> +       .supply_name    = "pwm",
> +};

nit: the pwm_regulator_desc can now be "const".


Neither of those is huge.  If you get no other feedback, Mark could
maybe give advice on whether you should spin your series or whether
he'd like to fix them when he applies.

Reviewed-by: Doug Anderson <dianders@chromium.org>

Re: [PATCH v3 2/2] dt-bindings: add devicetree bindings for st-pwm regulator

[Doug Anderson]

Chris,

On Fri, Sep 19, 2014 at 1:02 AM, Chris Zhong <zyw@rock-chips.com> wrote:
> Document the st-pwm regulator
>
> Signed-off-by: Chris Zhong <zyw@rock-chips.com>
>
> ---
>
> Changes in v3:
> Adviced by Doug Anderson
> - update the Example
>
> Changes in v2:
> Adviced by Lee Jones
> - rename the documentation
> Adviced by Doug Anderson
> - update the example
> Adviced by Mark Rutland
> - remove pwm-reg-period
>
>  .../bindings/regulator/pwm-regulator.txt           |   29 ++++++++++++++++++++
>  1 file changed, 29 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/regulator/pwm-regulator.txt
>
> diff --git a/Documentation/devicetree/bindings/regulator/pwm-regulator.txt b/Documentation/devicetree/bindings/regulator/pwm-regulator.txt
> new file mode 100644
> index 0000000..eb46f7b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/regulator/pwm-regulator.txt
> @@ -0,0 +1,29 @@
> +pwm regulator bindings
> +
> +Required properties:
> +- compatible: Should be "pwm-regulator"
> +- pwms: OF device-tree PWM specification (see PWM binding pwm.txt)
> +- voltage-table: voltage and duty table, include 2 merbers in each set of
> +  brackets, first one is voltage(unit: uv), the next is duty(unit: percent)
> +
> +Any property defined as part of the core regulator binding defined in
> +regulator.txt can also be used.
> +
> +Example:
> +       pwm_regulator {
> +               compatible = "pwm-regulator;
> +               pwms = <&pwm1 0 8448 0>;
> +
> +               voltage-table = <1114000 0>,
> +                               <1095000 10>,
> +                               <1076000 20>,
> +                               <1056000 30>,
> +                               <1036000 40>,
> +                               <1016000 50>;
> +
> +               regulator-always-on;
> +               regulator-boot-on;

I think Mark suggested that the two properties above were not useful
on a regulator that is always enabled.  That seems to match the code:

/* If we don't know then assume that the regulator is always on */
if (!rdev->desc->ops->is_enabled)
  return 1;

...so I'd remove them from your example...

Again, if there's no additional feedback you'd need Mark's advice
about whether he wants a respin.

Reviewed-by: Doug Anderson <dianders@chromium.org>