1 files changed, 298 insertions, 0 deletions
diff --git a/drivers/regulator/stm32-vrefbuf.c b/drivers/regulator/stm32-vrefbuf.c
new file mode 100644
index 0000000000..717144cbe0
--- /dev/null
+++ b/drivers/regulator/stm32-vrefbuf.c
@@ -0,0 +1,298 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) STMicroelectronics 2017
+ *
+ * Author: Fabrice Gasnier <fabrice.gasnier@st.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/of_regulator.h>
+#include <linux/pm_runtime.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)
+
+#define STM32_VREFBUF_AUTO_SUSPEND_DELAY_MS	10
+
+struct stm32_vrefbuf {
+	void __iomem *base;
+	struct clk *clk;
+	struct device *dev;
+};
+
+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;
+	int ret;
+
+	ret = pm_runtime_resume_and_get(priv->dev);
+	if (ret < 0)
+		return ret;
+
+	val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
+	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);
+	}
+
+	pm_runtime_mark_last_busy(priv->dev);
+	pm_runtime_put_autosuspend(priv->dev);
+
+	return ret;
+}
+
+static int stm32_vrefbuf_disable(struct regulator_dev *rdev)
+{
+	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
+	u32 val;
+	int ret;
+
+	ret = pm_runtime_resume_and_get(priv->dev);
+	if (ret < 0)
+		return ret;
+
+	val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
+	val &= ~STM32_ENVR;
+	writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
+
+	pm_runtime_mark_last_busy(priv->dev);
+	pm_runtime_put_autosuspend(priv->dev);
+
+	return 0;
+}
+
+static int stm32_vrefbuf_is_enabled(struct regulator_dev *rdev)
+{
+	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
+	int ret;
+
+	ret = pm_runtime_resume_and_get(priv->dev);
+	if (ret < 0)
+		return ret;
+
+	ret = readl_relaxed(priv->base + STM32_VREFBUF_CSR) & STM32_ENVR;
+
+	pm_runtime_mark_last_busy(priv->dev);
+	pm_runtime_put_autosuspend(priv->dev);
+
+	return ret;
+}
+
+static int stm32_vrefbuf_set_voltage_sel(struct regulator_dev *rdev,
+					 unsigned sel)
+{
+	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
+	u32 val;
+	int ret;
+
+	ret = pm_runtime_resume_and_get(priv->dev);
+	if (ret < 0)
+		return ret;
+
+	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);
+
+	pm_runtime_mark_last_busy(priv->dev);
+	pm_runtime_put_autosuspend(priv->dev);
+
+	return 0;
+}
+
+static int stm32_vrefbuf_get_voltage_sel(struct regulator_dev *rdev)
+{
+	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
+	u32 val;
+	int ret;
+
+	ret = pm_runtime_resume_and_get(priv->dev);
+	if (ret < 0)
+		return ret;
+
+	val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
+	ret = FIELD_GET(STM32_VRS, val);
+
+	pm_runtime_mark_last_busy(priv->dev);
+	pm_runtime_put_autosuspend(priv->dev);
+
+	return ret;
+}
+
+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,
+	.off_on_delay = 1000,
+	.type = REGULATOR_VOLTAGE,
+	.owner = THIS_MODULE,
+};
+
+static int stm32_vrefbuf_probe(struct platform_device *pdev)
+{
+	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;
+	priv->dev = &pdev->dev;
+
+	priv->base = devm_platform_ioremap_resource(pdev, 0);
+	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);
+
+	pm_runtime_get_noresume(&pdev->dev);
+	pm_runtime_set_active(&pdev->dev);
+	pm_runtime_set_autosuspend_delay(&pdev->dev,
+					 STM32_VREFBUF_AUTO_SUSPEND_DELAY_MS);
+	pm_runtime_use_autosuspend(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+
+	ret = clk_prepare_enable(priv->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "clk prepare failed with error %d\n", ret);
+		goto err_pm_stop;
+	}
+
+	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(&pdev->dev, &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);
+
+	pm_runtime_mark_last_busy(&pdev->dev);
+	pm_runtime_put_autosuspend(&pdev->dev);
+
+	return 0;
+
+err_clk_dis:
+	clk_disable_unprepare(priv->clk);
+err_pm_stop:
+	pm_runtime_disable(&pdev->dev);
+	pm_runtime_set_suspended(&pdev->dev);
+	pm_runtime_put_noidle(&pdev->dev);
+
+	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);
+
+	pm_runtime_get_sync(&pdev->dev);
+	regulator_unregister(rdev);
+	clk_disable_unprepare(priv->clk);
+	pm_runtime_disable(&pdev->dev);
+	pm_runtime_set_suspended(&pdev->dev);
+	pm_runtime_put_noidle(&pdev->dev);
+
+	return 0;
+};
+
+static int __maybe_unused stm32_vrefbuf_runtime_suspend(struct device *dev)
+{
+	struct regulator_dev *rdev = dev_get_drvdata(dev);
+	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
+
+	clk_disable_unprepare(priv->clk);
+
+	return 0;
+}
+
+static int __maybe_unused stm32_vrefbuf_runtime_resume(struct device *dev)
+{
+	struct regulator_dev *rdev = dev_get_drvdata(dev);
+	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
+
+	return clk_prepare_enable(priv->clk);
+}
+
+static const struct dev_pm_ops stm32_vrefbuf_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+				pm_runtime_force_resume)
+	SET_RUNTIME_PM_OPS(stm32_vrefbuf_runtime_suspend,
+			   stm32_vrefbuf_runtime_resume,
+			   NULL)
+};
+
+static const struct of_device_id __maybe_unused 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",
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+		.of_match_table = of_match_ptr(stm32_vrefbuf_of_match),
+		.pm = &stm32_vrefbuf_pm_ops,
+	},
+};
+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");