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drivers/regulator/stm32-vrefbuf.c
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/* * 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! "); 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 ", 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 ", 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"); |