[PATCH 0/3] Add support for STM32 vrefbuf regulator

[PATCH 0/3] Add support for STM32 vrefbuf regulator

[Fabrice Gasnier]

Some STM32 devices embed a voltage reference buffer which can be used as
voltage reference for ADCs, DACs and also as voltage reference
for external components through the dedicated VREF+ pin.

This patchset adds vrefbuf regulator driver, device tree bindings and
vrefbuf device tree node for STM32H7 SoC.

Fabrice Gasnier (3):
  dt-bindings: regulator: Add STM32 Voltage Reference Buffer
  regulator: Add support for stm32-vrefbuf
  ARM: dts: stm32: add vrefbuf to stm32h743

 .../bindings/regulator/st,stm32-vrefbuf.txt        |  20 ++
 arch/arm/boot/dts/stm32h743.dtsi                   |   9 +
 drivers/regulator/Kconfig                          |  12 ++
 drivers/regulator/Makefile                         |   1 +
 drivers/regulator/stm32-vrefbuf.c                  | 215 +++++++++++++++++++++
 5 files changed, 257 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/regulator/st,stm32-vrefbuf.txt
 create mode 100644 drivers/regulator/stm32-vrefbuf.c

-- 
1.9.1

[PATCH 1/3] dt-bindings: regulator: Add STM32 Voltage Reference Buffer

[Fabrice Gasnier]

Document STM32 VREFBUF (voltage reference buffer) which can be used as
voltage reference for ADCs, DACs and external components.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
 .../bindings/regulator/st,stm32-vrefbuf.txt          | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/regulator/st,stm32-vrefbuf.txt

diff --git a/Documentation/devicetree/bindings/regulator/st,stm32-vrefbuf.txt b/Documentation/devicetree/bindings/regulator/st,stm32-vrefbuf.txt
new file mode 100644
index 0000000..3944ee3
--- /dev/null
+++ b/Documentation/devicetree/bindings/regulator/st,stm32-vrefbuf.txt
@@ -0,0 +1,20 @@
+STM32 VREFBUF - Voltage reference buffer
+
+Some STM32 devices embed a voltage reference buffer which can be used as
+voltage reference for ADCs, DACs and also as voltage reference for external
+components through the dedicated VREF+ pin.
+
+Required properties:
+- compatible:		Must be "st,stm32-vrefbuf".
+- reg:			Offset and length of VREFBUF register set.
+- clocks:		Must contain an entry for peripheral clock.
+
+Example:
+	vrefbuf: regulator at 58003C00 {
+		compatible = "st,stm32-vrefbuf";
+		reg = <0x58003C00 0x8>;
+		clocks = <&rcc VREF_CK>;
+		regulator-min-microvolt = <1500000>;
+		regulator-max-microvolt = <2500000>;
+		vdda-supply = <&vdda>;
+	};
-- 
1.9.1

[PATCH 1/3] dt-bindings: regulator: Add STM32 Voltage Reference Buffer

[Rob Herring]

On Tue, Jul 11, 2017 at 02:30:31PM +0200, Fabrice Gasnier wrote:
> Document STM32 VREFBUF (voltage reference buffer) which can be used as
> voltage reference for ADCs, DACs and external components.
> 
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
> ---
>  .../bindings/regulator/st,stm32-vrefbuf.txt          | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/regulator/st,stm32-vrefbuf.txt

Acked-by: Rob Herring <robh@kernel.org>

Applied "regulator: Add STM32 Voltage Reference Buffer" to the regulator tree

[Mark Brown]

The patch

   regulator: Add STM32 Voltage Reference Buffer

has been applied to the regulator tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From ef7bb293a670c7a81c7a5b8aad6b93ba32e0e9ec Mon Sep 17 00:00:00 2001
From: Fabrice Gasnier <fabrice.gasnier@st.com>
Date: Wed, 30 Aug 2017 17:55:27 +0200
Subject: [PATCH] regulator: Add STM32 Voltage Reference Buffer

Document STM32 VREFBUF (voltage reference buffer) which can be used as
voltage reference for ADCs, DACs and external components.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 .../bindings/regulator/st,stm32-vrefbuf.txt          | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/regulator/st,stm32-vrefbuf.txt

diff --git a/Documentation/devicetree/bindings/regulator/st,stm32-vrefbuf.txt b/Documentation/devicetree/bindings/regulator/st,stm32-vrefbuf.txt
new file mode 100644
index 000000000000..3944ee3e731e
--- /dev/null
+++ b/Documentation/devicetree/bindings/regulator/st,stm32-vrefbuf.txt
@@ -0,0 +1,20 @@
+STM32 VREFBUF - Voltage reference buffer
+
+Some STM32 devices embed a voltage reference buffer which can be used as
+voltage reference for ADCs, DACs and also as voltage reference for external
+components through the dedicated VREF+ pin.
+
+Required properties:
+- compatible:		Must be "st,stm32-vrefbuf".
+- reg:			Offset and length of VREFBUF register set.
+- clocks:		Must contain an entry for peripheral clock.
+
+Example:
+	vrefbuf: regulator at 58003C00 {
+		compatible = "st,stm32-vrefbuf";
+		reg = <0x58003C00 0x8>;
+		clocks = <&rcc VREF_CK>;
+		regulator-min-microvolt = <1500000>;
+		regulator-max-microvolt = <2500000>;
+		vdda-supply = <&vdda>;
+	};
-- 
2.14.1

[PATCH 2/3] regulator: Add support for stm32-vrefbuf

[Fabrice Gasnier]

Add regulator driver for STM32 voltage reference buffer which can be
used as voltage reference for ADCs, DACs and external components through
dedicated VREF+ pin.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
 drivers/regulator/Kconfig         |  12 +++
 drivers/regulator/Makefile        |   1 +
 drivers/regulator/stm32-vrefbuf.c | 215 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 228 insertions(+)
 create mode 100644 drivers/regulator/stm32-vrefbuf.c

diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 48db87d..7950283 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -728,6 +728,18 @@ config REGULATOR_SKY81452
 	  This driver can also be built as a module. If so, the module
 	  will be called sky81452-regulator.
 
+config REGULATOR_STM32_VREFBUF
+	tristate "STMicroelectronics STM32 VREFBUF"
+	depends on ARCH_STM32 || COMPILE_TEST
+	help
+	  This driver supports STMicroelectronics STM32 VREFBUF (voltage
+	  reference buffer) which can be used as voltage reference for
+	  internal ADCs, DACs and also for external components through
+	  dedicated Vref+ pin.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called stm32-vrefbuf.
+
 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 dc3503f..d8caceb 100644
--- a/drivers/regulator/Makefile
+++ b/drivers/regulator/Makefile
@@ -92,6 +92,7 @@ obj-$(CONFIG_REGULATOR_S2MPA01) += s2mpa01.o
 obj-$(CONFIG_REGULATOR_S2MPS11) += s2mps11.o
 obj-$(CONFIG_REGULATOR_S5M8767) += s5m8767.o
 obj-$(CONFIG_REGULATOR_SKY81452) += sky81452-regulator.o
+obj-$(CONFIG_REGULATOR_STM32_VREFBUF) += stm32-vrefbuf.o
 obj-$(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/stm32-vrefbuf.c b/drivers/regulator/stm32-vrefbuf.c
new file mode 100644
index 0000000..a4efa3b
--- /dev/null
+++ b/drivers/regulator/stm32-vrefbuf.c
@@ -0,0 +1,215 @@
+/*
+ * Copyright (C) STMicroelectronics 2017
+ *
+ * Author: Fabrice Gasnier <fabrice.gasnier@st.com>
+ *
+ * License terms:  GNU General Public License (GPL), version 2
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/of_regulator.h>
+
+/* STM32 VREFBUF registers */
+#define STM32_VREFBUF_CSR		0x00
+
+/* STM32 VREFBUF CSR bitfields */
+#define STM32_VRS			GENMASK(6, 4)
+#define STM32_VRR			BIT(3)
+#define STM32_HIZ			BIT(1)
+#define STM32_ENVR			BIT(0)
+
+struct stm32_vrefbuf {
+	void __iomem *base;
+	struct clk *clk;
+};
+
+static const unsigned int stm32_vrefbuf_voltages[] = {
+	/* Matches resp. VRS = 000b, 001b, 010b, 011b */
+	2500000, 2048000, 1800000, 1500000,
+};
+
+static int stm32_vrefbuf_enable(struct regulator_dev *rdev)
+{
+	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
+	u32 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
+	int ret;
+
+	val = (val & ~STM32_HIZ) | STM32_ENVR;
+	writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
+
+	/*
+	 * Vrefbuf startup time depends on external capacitor: wait here for
+	 * VRR to be set. That means output has reached expected value.
+	 * ~650us sleep should be enough for caps up to 1.5uF. Use 10ms as
+	 * arbitrary timeout.
+	 */
+	ret = readl_poll_timeout(priv->base + STM32_VREFBUF_CSR, val,
+				 !(val & STM32_VRR), 650, 10000);
+	if (ret) {
+		dev_err(&rdev->dev, "stm32 vrefbuf timed out!\n");
+		val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
+		val = (val & ~STM32_ENVR) | STM32_HIZ;
+		writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
+	}
+
+	return ret;
+}
+
+static int stm32_vrefbuf_disable(struct regulator_dev *rdev)
+{
+	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
+	u32 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
+
+	val = (val & ~STM32_ENVR) | STM32_HIZ;
+	writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
+
+	return 0;
+}
+
+static int stm32_vrefbuf_is_enabled(struct regulator_dev *rdev)
+{
+	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
+
+	return readl_relaxed(priv->base + STM32_VREFBUF_CSR) & STM32_ENVR;
+}
+
+static int stm32_vrefbuf_set_voltage_sel(struct regulator_dev *rdev,
+					 unsigned sel)
+{
+	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
+	u32 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
+
+	val = (val & ~STM32_VRS) | FIELD_PREP(STM32_VRS, sel);
+	writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
+
+	return 0;
+}
+
+static int stm32_vrefbuf_get_voltage_sel(struct regulator_dev *rdev)
+{
+	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
+	u32 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
+
+	return FIELD_GET(STM32_VRS, val);
+}
+
+static const struct regulator_ops stm32_vrefbuf_volt_ops = {
+	.enable		= stm32_vrefbuf_enable,
+	.disable	= stm32_vrefbuf_disable,
+	.is_enabled	= stm32_vrefbuf_is_enabled,
+	.get_voltage_sel = stm32_vrefbuf_get_voltage_sel,
+	.set_voltage_sel = stm32_vrefbuf_set_voltage_sel,
+	.list_voltage	= regulator_list_voltage_table,
+};
+
+static const struct regulator_desc stm32_vrefbuf_regu = {
+	.name = "vref",
+	.supply_name = "vdda",
+	.volt_table = stm32_vrefbuf_voltages,
+	.n_voltages = ARRAY_SIZE(stm32_vrefbuf_voltages),
+	.ops = &stm32_vrefbuf_volt_ops,
+	.type = REGULATOR_VOLTAGE,
+	.owner = THIS_MODULE,
+};
+
+static int stm32_vrefbuf_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct stm32_vrefbuf *priv;
+	struct regulator_config config = { };
+	struct regulator_dev *rdev;
+	int ret;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	priv->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(priv->base))
+		return PTR_ERR(priv->base);
+
+	priv->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(priv->clk))
+		return PTR_ERR(priv->clk);
+
+	ret = clk_prepare_enable(priv->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "clk prepare failed\n");
+		return ret;
+	}
+
+	config.dev = &pdev->dev;
+	config.driver_data = priv;
+	config.of_node = pdev->dev.of_node;
+	config.init_data = of_get_regulator_init_data(&pdev->dev,
+						      pdev->dev.of_node,
+						      &stm32_vrefbuf_regu);
+
+	rdev = regulator_register(&stm32_vrefbuf_regu, &config);
+	if (IS_ERR(rdev)) {
+		dev_err(&pdev->dev, "vrefbuf register failed\n");
+		ret = PTR_ERR(rdev);
+		goto err_clk_dis;
+	}
+	platform_set_drvdata(pdev, rdev);
+
+	dev_info(&pdev->dev, "STM32 VREFBUF initialized\n");
+
+	return 0;
+
+err_clk_dis:
+	clk_disable_unprepare(priv->clk);
+
+	return ret;
+}
+
+static int stm32_vrefbuf_remove(struct platform_device *pdev)
+{
+	struct regulator_dev *rdev = platform_get_drvdata(pdev);
+	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
+
+	regulator_unregister(rdev);
+	clk_disable_unprepare(priv->clk);
+
+	return 0;
+};
+
+static const struct of_device_id stm32_vrefbuf_of_match[] = {
+	{ .compatible = "st,stm32-vrefbuf", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, stm32_vrefbuf_of_match);
+
+static struct platform_driver stm32_vrefbuf_driver = {
+	.probe = stm32_vrefbuf_probe,
+	.remove = stm32_vrefbuf_remove,
+	.driver = {
+		.name  = "stm32-vrefbuf",
+		.of_match_table = of_match_ptr(stm32_vrefbuf_of_match),
+	},
+};
+
+static int __init stm32_vrefbuf_init(void)
+{
+	return platform_driver_register(&stm32_vrefbuf_driver);
+}
+subsys_initcall(stm32_vrefbuf_init);
+
+static void __exit stm32_vrefbuf_exit(void)
+{
+	platform_driver_unregister(&stm32_vrefbuf_driver);
+}
+module_exit(stm32_vrefbuf_exit)
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
+MODULE_DESCRIPTION("STMicroelectronics STM32 VREFBUF driver");
+MODULE_ALIAS("platform:stm32-vrefbuf");
-- 
1.9.1

[PATCH 3/3] ARM: dts: stm32: add vrefbuf to stm32h743

[Fabrice Gasnier]

Add STM32H743 VREFBUF (Voltage Reference Buffer) definition.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
 arch/arm/boot/dts/stm32h743.dtsi | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/arm/boot/dts/stm32h743.dtsi b/arch/arm/boot/dts/stm32h743.dtsi
index 4685629..c57096a 100644
--- a/arch/arm/boot/dts/stm32h743.dtsi
+++ b/arch/arm/boot/dts/stm32h743.dtsi
@@ -74,6 +74,15 @@
 			interrupts = <50>;
 			clocks = <&timer_clk>;
 		};
+
+		vrefbuf: regulator at 58003C00 {
+			compatible = "st,stm32-vrefbuf";
+			reg = <0x58003C00 0x8>;
+			clocks = <&timer_clk>;
+			regulator-min-microvolt = <1500000>;
+			regulator-max-microvolt = <2500000>;
+			status = "disabled";
+		};
 	};
 };
 
-- 
1.9.1