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 (file)
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 (file)
--- a/drivers/power/regulator/Kconfig
+++ b/drivers/power/regulator/Kconfig
@@ -197,6 +197,15 @@ config DM_REGULATOR_LP87565
        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 (file)
--- a/drivers/power/regulator/Makefile
+++ b/drivers/power/regulator/Makefile
@@ -22,5 +22,6 @@ obj-$(CONFIG_$(SPL_)DM_REGULATOR_PALMAS) += palmas_regulator.o
 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 (file)
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),
+};