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
Document STM32 VREFBUF (voltage reference buffer) which can be used as
voltage reference for ADCs, DACs and external components.
Signed-off-by: Fabrice Gasnier <[email protected]>
Acked-by: Rob Herring <[email protected]>
---
.../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@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
Add STM32H743 VREFBUF (Voltage Reference Buffer) definition.
Signed-off-by: Fabrice Gasnier <[email protected]>
---
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 36a99db..83ee8fe 100644
--- a/arch/arm/boot/dts/stm32h743.dtsi
+++ b/arch/arm/boot/dts/stm32h743.dtsi
@@ -82,6 +82,15 @@
interrupts = <50>;
clocks = <&timer_clk>;
};
+
+ vrefbuf: regulator@58003C00 {
+ compatible = "st,stm32-vrefbuf";
+ reg = <0x58003C00 0x8>;
+ clocks = <&timer_clk>;
+ regulator-min-microvolt = <1500000>;
+ regulator-max-microvolt = <2500000>;
+ status = "disabled";
+ };
};
};
--
1.9.1
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 <[email protected]>
---
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 99b9362..2cb2c63 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -746,6 +746,18 @@ 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 95b1e86..5af3788 100644
--- a/drivers/regulator/Makefile
+++ b/drivers/regulator/Makefile
@@ -94,6 +94,7 @@ 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 <[email protected]>
+ *
+ * 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 <[email protected]>");
+MODULE_DESCRIPTION("STMicroelectronics STM32 VREFBUF driver");
+MODULE_ALIAS("platform:stm32-vrefbuf");
--
1.9.1
On Mon, Aug 28, 2017 at 02:58:52PM +0200, Fabrice Gasnier wrote:
> + ret = clk_prepare_enable(priv->clk);
> + if (ret) {
> + dev_err(&pdev->dev, "clk prepare failed\n");
If you're printing an error include the error code, it'll help users
figure out what went wrong.
> + dev_info(&pdev->dev, "STM32 VREFBUF initialized\n");
This is just noise, remove it.
> +static int __init stm32_vrefbuf_init(void)
> +{
> + return platform_driver_register(&stm32_vrefbuf_driver);
> +}
> +subsys_initcall(stm32_vrefbuf_init);
Why is this at subsys_initcall()?
On 08/29/2017 08:57 PM, Mark Brown wrote:
> On Mon, Aug 28, 2017 at 02:58:52PM +0200, Fabrice Gasnier wrote:
>
>> + ret = clk_prepare_enable(priv->clk);
>> + if (ret) {
>> + dev_err(&pdev->dev, "clk prepare failed\n");
>
> If you're printing an error include the error code, it'll help users
> figure out what went wrong.
Hi Mark,
Thanks for reviewing,
I'll add it in v2.
>
>> + dev_info(&pdev->dev, "STM32 VREFBUF initialized\n");
>
> This is just noise, remove it.
I'll remove it in v2.
>
>> +static int __init stm32_vrefbuf_init(void)
>> +{
>> + return platform_driver_register(&stm32_vrefbuf_driver);
>> +}
>> +subsys_initcall(stm32_vrefbuf_init);
>
> Why is this at subsys_initcall()?
>
Several consumers depend on it when it's being used, among which: STM32
internal ADC and DAC, but also external components. Purpose is to ensure
it's ready before these drivers gets probed, instead of being deferred.
Is it ok to keep it ?
Please let me know,
Best Regards,
Fabrice
On Wed, Aug 30, 2017 at 11:11:24AM +0200, Fabrice Gasnier wrote:
> On 08/29/2017 08:57 PM, Mark Brown wrote:
> > On Mon, Aug 28, 2017 at 02:58:52PM +0200, Fabrice Gasnier wrote:
> >> +static int __init stm32_vrefbuf_init(void)
> >> +{
> >> + return platform_driver_register(&stm32_vrefbuf_driver);
> >> +}
> >> +subsys_initcall(stm32_vrefbuf_init);
> > Why is this at subsys_initcall()?
> Several consumers depend on it when it's being used, among which: STM32
> internal ADC and DAC, but also external components. Purpose is to ensure
> it's ready before these drivers gets probed, instead of being deferred.
> Is it ok to keep it ?
No, that's not OK - just let deferred probe handle it. The same thing
applies to all regulator usage.
On 08/30/2017 05:02 PM, Mark Brown wrote:
> On Wed, Aug 30, 2017 at 11:11:24AM +0200, Fabrice Gasnier wrote:
>> On 08/29/2017 08:57 PM, Mark Brown wrote:
>>> On Mon, Aug 28, 2017 at 02:58:52PM +0200, Fabrice Gasnier wrote:
>
>>>> +static int __init stm32_vrefbuf_init(void)
>>>> +{
>>>> + return platform_driver_register(&stm32_vrefbuf_driver);
>>>> +}
>>>> +subsys_initcall(stm32_vrefbuf_init);
>
>>> Why is this at subsys_initcall()?
>
>> Several consumers depend on it when it's being used, among which: STM32
>> internal ADC and DAC, but also external components. Purpose is to ensure
>> it's ready before these drivers gets probed, instead of being deferred.
>> Is it ok to keep it ?
>
> No, that's not OK - just let deferred probe handle it. The same thing
> applies to all regulator usage.
>
Hi Mark,
Ok, I'll update this in v2 as well.
Thanks,
Fabrice