regulator: Add support for stm32-vrefbuf
authorFabrice Gasnier <fabrice.gasnier@st.com>
Wed, 30 Aug 2017 15:55:28 +0000 (17:55 +0200)
committerMark Brown <broonie@kernel.org>
Wed, 30 Aug 2017 17:28:35 +0000 (18:28 +0100)
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: Mark Brown <broonie@kernel.org>
drivers/regulator/Kconfig
drivers/regulator/Makefile
drivers/regulator/stm32-vrefbuf.c [new file with mode: 0644]

index 99b9362331b56ad5f7b6aae08c7c290e80c269e9..2cb2c6324480435def64a71372c0fd64fbf54434 100644 (file)
@@ -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.
 
          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
 config REGULATOR_TI_ABB
        tristate "TI Adaptive Body Bias on-chip LDO"
        depends on ARCH_OMAP
index 95b1e86ae692ba897b3b80f2d2e6d99b70006e88..5af3788be6312e337b5d59e7baad5393f4c4c1aa 100644 (file)
@@ -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-$(CONFIG_REGULATOR_S2MPS11) += s2mps11.o
 obj-$(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-$(CONFIG_REGULATOR_TPS6105X) += tps6105x-regulator.o
 obj-$(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 (file)
index 0000000..72c8b3e
--- /dev/null
@@ -0,0 +1,202 @@
+/*
+ * 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 with error %d\n", ret);
+               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)) {
+               ret = PTR_ERR(rdev);
+               dev_err(&pdev->dev, "register failed with error %d\n", ret);
+               goto err_clk_dis;
+       }
+       platform_set_drvdata(pdev, rdev);
+
+       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),
+       },
+};
+module_platform_driver(stm32_vrefbuf_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
+MODULE_DESCRIPTION("STMicroelectronics STM32 VREFBUF driver");
+MODULE_ALIAS("platform:stm32-vrefbuf");