power: regulator: Add support for stm32-vrefbuf
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>
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
diff --git a/doc/device-tree-bindings/regulator/st,stm32-vrefbuf.txt b/doc/device-tree-bindings/regulator/st,stm32-vrefbuf.txt
new file mode 100644
index 0000000..0f6b6fe
--- /dev/null
+++ b/doc/device-tree-bindings/regulator/st,stm32-vrefbuf.txt
@@ -0,0 +1,23 @@
+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.
+
+Optional properties:
+- vdda-supply: Phandle to the parent vdda supply regulator node.
+
+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>;
+ };
diff --git a/drivers/power/regulator/Kconfig b/drivers/power/regulator/Kconfig
index 822cff6..414f4a5 100644
--- a/drivers/power/regulator/Kconfig
+++ b/drivers/power/regulator/Kconfig
@@ -197,6 +197,15 @@
be configured in multi phase modes. The driver implements
get/set api for value and enable.
+config DM_REGULATOR_STM32_VREFBUF
+ bool "Enable driver for STMicroelectronics STM32 VREFBUF"
+ depends on DM_REGULATOR && (STM32H7 || ARCH_STM32MP)
+ 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.
+
config DM_REGULATOR_TPS65910
bool "Enable driver for TPS65910 PMIC regulators"
depends on DM_PMIC_TPS65910
diff --git a/drivers/power/regulator/Makefile b/drivers/power/regulator/Makefile
index d73a6e3..16208af 100644
--- a/drivers/power/regulator/Makefile
+++ b/drivers/power/regulator/Makefile
@@ -22,5 +22,6 @@
obj-$(CONFIG_$(SPL_)DM_REGULATOR_PBIAS) += pbias_regulator.o
obj-$(CONFIG_$(SPL_)DM_REGULATOR_LP873X) += lp873x_regulator.o
obj-$(CONFIG_$(SPL_)DM_REGULATOR_LP87565) += lp87565_regulator.o
+obj-$(CONFIG_$(SPL_)DM_REGULATOR_STM32_VREFBUF) += stm32-vrefbuf.o
obj-$(CONFIG_DM_REGULATOR_TPS65910) += tps65910_regulator.o
obj-$(CONFIG_$(SPL_)DM_REGULATOR_STPMU1) += stpmu1.o
diff --git a/drivers/power/regulator/stm32-vrefbuf.c b/drivers/power/regulator/stm32-vrefbuf.c
new file mode 100644
index 0000000..0ad6833
--- /dev/null
+++ b/drivers/power/regulator/stm32-vrefbuf.c
@@ -0,0 +1,155 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2018, STMicroelectronics - All Rights Reserved
+ * Author: Fabrice Gasnier <fabrice.gasnier@st.com>
+ *
+ * Originally based on the Linux kernel v4.16 drivers/regulator/stm32-vrefbuf.c
+ */
+
+#include <common.h>
+#include <clk.h>
+#include <dm.h>
+#include <asm/io.h>
+#include <linux/iopoll.h>
+#include <linux/kernel.h>
+#include <power/regulator.h>
+
+/* STM32 VREFBUF registers */
+#define STM32_VREFBUF_CSR 0x00
+
+/* STM32 VREFBUF CSR bitfields */
+#define STM32_VRS GENMASK(6, 4)
+#define STM32_VRS_SHIFT 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;
+ struct udevice *vdda_supply;
+};
+
+static const unsigned int stm32_vrefbuf_voltages[] = {
+ /* Matches resp. VRS = 000b, 001b, 010b, 011b */
+ 2500000, 2048000, 1800000, 1500000,
+};
+
+static int stm32_vrefbuf_set_enable(struct udevice *dev, bool enable)
+{
+ struct stm32_vrefbuf *priv = dev_get_priv(dev);
+ u32 val;
+ int ret;
+
+ clrsetbits_le32(priv->base + STM32_VREFBUF_CSR, STM32_HIZ | STM32_ENVR,
+ enable ? STM32_ENVR : STM32_HIZ);
+ if (!enable)
+ return 0;
+
+ /*
+ * 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, 10000);
+ if (ret < 0) {
+ dev_err(dev, "stm32 vrefbuf timed out: %d\n", ret);
+ clrsetbits_le32(priv->base + STM32_VREFBUF_CSR, STM32_ENVR,
+ STM32_HIZ);
+ return ret;
+ }
+
+ return 0;
+}
+
+static int stm32_vrefbuf_get_enable(struct udevice *dev)
+{
+ struct stm32_vrefbuf *priv = dev_get_priv(dev);
+
+ return readl(priv->base + STM32_VREFBUF_CSR) & STM32_ENVR;
+}
+
+static int stm32_vrefbuf_set_value(struct udevice *dev, int uV)
+{
+ struct stm32_vrefbuf *priv = dev_get_priv(dev);
+ unsigned int i;
+
+ for (i = 0; i < ARRAY_SIZE(stm32_vrefbuf_voltages); i++) {
+ if (uV == stm32_vrefbuf_voltages[i]) {
+ clrsetbits_le32(priv->base + STM32_VREFBUF_CSR,
+ STM32_VRS, i << STM32_VRS_SHIFT);
+ return 0;
+ }
+ }
+
+ return -EINVAL;
+}
+
+static int stm32_vrefbuf_get_value(struct udevice *dev)
+{
+ struct stm32_vrefbuf *priv = dev_get_priv(dev);
+ u32 val;
+
+ val = readl(priv->base + STM32_VREFBUF_CSR) & STM32_VRS;
+ val >>= STM32_VRS_SHIFT;
+
+ return stm32_vrefbuf_voltages[val];
+}
+
+static const struct dm_regulator_ops stm32_vrefbuf_ops = {
+ .get_value = stm32_vrefbuf_get_value,
+ .set_value = stm32_vrefbuf_set_value,
+ .get_enable = stm32_vrefbuf_get_enable,
+ .set_enable = stm32_vrefbuf_set_enable,
+};
+
+static int stm32_vrefbuf_probe(struct udevice *dev)
+{
+ struct stm32_vrefbuf *priv = dev_get_priv(dev);
+ int ret;
+
+ priv->base = dev_read_addr_ptr(dev);
+
+ ret = clk_get_by_index(dev, 0, &priv->clk);
+ if (ret) {
+ dev_err(dev, "Can't get clock: %d\n", ret);
+ return ret;
+ }
+
+ ret = clk_enable(&priv->clk);
+ if (ret) {
+ dev_err(dev, "Can't enable clock: %d\n", ret);
+ return ret;
+ }
+
+ ret = device_get_supply_regulator(dev, "vdda-supply",
+ &priv->vdda_supply);
+ if (ret) {
+ dev_dbg(dev, "No vdda-supply: %d\n", ret);
+ return 0;
+ }
+
+ ret = regulator_set_enable(priv->vdda_supply, true);
+ if (ret) {
+ dev_err(dev, "Can't enable vdda-supply: %d\n", ret);
+ clk_disable(&priv->clk);
+ }
+
+ return ret;
+}
+
+static const struct udevice_id stm32_vrefbuf_ids[] = {
+ { .compatible = "st,stm32-vrefbuf" },
+ { }
+};
+
+U_BOOT_DRIVER(stm32_vrefbuf) = {
+ .name = "stm32-vrefbuf",
+ .id = UCLASS_REGULATOR,
+ .of_match = stm32_vrefbuf_ids,
+ .probe = stm32_vrefbuf_probe,
+ .ops = &stm32_vrefbuf_ops,
+ .priv_auto_alloc_size = sizeof(struct stm32_vrefbuf),
+};