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| 1 | +/* |
| 2 | + * Copyright (C) STMicroelectronics 2017 |
| 3 | + * |
| 4 | + * Author: Fabrice Gasnier <[email protected]> |
| 5 | + * |
| 6 | + * License terms: GNU General Public License (GPL), version 2 |
| 7 | + */ |
| 8 | + |
| 9 | +#include <linux/bitfield.h> |
| 10 | +#include <linux/clk.h> |
| 11 | +#include <linux/io.h> |
| 12 | +#include <linux/iopoll.h> |
| 13 | +#include <linux/module.h> |
| 14 | +#include <linux/of_device.h> |
| 15 | +#include <linux/platform_device.h> |
| 16 | +#include <linux/regulator/driver.h> |
| 17 | +#include <linux/regulator/of_regulator.h> |
| 18 | + |
| 19 | +/* STM32 VREFBUF registers */ |
| 20 | +#define STM32_VREFBUF_CSR 0x00 |
| 21 | + |
| 22 | +/* STM32 VREFBUF CSR bitfields */ |
| 23 | +#define STM32_VRS GENMASK(6, 4) |
| 24 | +#define STM32_VRR BIT(3) |
| 25 | +#define STM32_HIZ BIT(1) |
| 26 | +#define STM32_ENVR BIT(0) |
| 27 | + |
| 28 | +struct stm32_vrefbuf { |
| 29 | + void __iomem *base; |
| 30 | + struct clk *clk; |
| 31 | +}; |
| 32 | + |
| 33 | +static const unsigned int stm32_vrefbuf_voltages[] = { |
| 34 | + /* Matches resp. VRS = 000b, 001b, 010b, 011b */ |
| 35 | + 2500000, 2048000, 1800000, 1500000, |
| 36 | +}; |
| 37 | + |
| 38 | +static int stm32_vrefbuf_enable(struct regulator_dev *rdev) |
| 39 | +{ |
| 40 | + struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev); |
| 41 | + u32 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR); |
| 42 | + int ret; |
| 43 | + |
| 44 | + val = (val & ~STM32_HIZ) | STM32_ENVR; |
| 45 | + writel_relaxed(val, priv->base + STM32_VREFBUF_CSR); |
| 46 | + |
| 47 | + /* |
| 48 | + * Vrefbuf startup time depends on external capacitor: wait here for |
| 49 | + * VRR to be set. That means output has reached expected value. |
| 50 | + * ~650us sleep should be enough for caps up to 1.5uF. Use 10ms as |
| 51 | + * arbitrary timeout. |
| 52 | + */ |
| 53 | + ret = readl_poll_timeout(priv->base + STM32_VREFBUF_CSR, val, |
| 54 | + !(val & STM32_VRR), 650, 10000); |
| 55 | + if (ret) { |
| 56 | + dev_err(&rdev->dev, "stm32 vrefbuf timed out!\n"); |
| 57 | + val = readl_relaxed(priv->base + STM32_VREFBUF_CSR); |
| 58 | + val = (val & ~STM32_ENVR) | STM32_HIZ; |
| 59 | + writel_relaxed(val, priv->base + STM32_VREFBUF_CSR); |
| 60 | + } |
| 61 | + |
| 62 | + return ret; |
| 63 | +} |
| 64 | + |
| 65 | +static int stm32_vrefbuf_disable(struct regulator_dev *rdev) |
| 66 | +{ |
| 67 | + struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev); |
| 68 | + u32 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR); |
| 69 | + |
| 70 | + val = (val & ~STM32_ENVR) | STM32_HIZ; |
| 71 | + writel_relaxed(val, priv->base + STM32_VREFBUF_CSR); |
| 72 | + |
| 73 | + return 0; |
| 74 | +} |
| 75 | + |
| 76 | +static int stm32_vrefbuf_is_enabled(struct regulator_dev *rdev) |
| 77 | +{ |
| 78 | + struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev); |
| 79 | + |
| 80 | + return readl_relaxed(priv->base + STM32_VREFBUF_CSR) & STM32_ENVR; |
| 81 | +} |
| 82 | + |
| 83 | +static int stm32_vrefbuf_set_voltage_sel(struct regulator_dev *rdev, |
| 84 | + unsigned sel) |
| 85 | +{ |
| 86 | + struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev); |
| 87 | + u32 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR); |
| 88 | + |
| 89 | + val = (val & ~STM32_VRS) | FIELD_PREP(STM32_VRS, sel); |
| 90 | + writel_relaxed(val, priv->base + STM32_VREFBUF_CSR); |
| 91 | + |
| 92 | + return 0; |
| 93 | +} |
| 94 | + |
| 95 | +static int stm32_vrefbuf_get_voltage_sel(struct regulator_dev *rdev) |
| 96 | +{ |
| 97 | + struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev); |
| 98 | + u32 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR); |
| 99 | + |
| 100 | + return FIELD_GET(STM32_VRS, val); |
| 101 | +} |
| 102 | + |
| 103 | +static const struct regulator_ops stm32_vrefbuf_volt_ops = { |
| 104 | + .enable = stm32_vrefbuf_enable, |
| 105 | + .disable = stm32_vrefbuf_disable, |
| 106 | + .is_enabled = stm32_vrefbuf_is_enabled, |
| 107 | + .get_voltage_sel = stm32_vrefbuf_get_voltage_sel, |
| 108 | + .set_voltage_sel = stm32_vrefbuf_set_voltage_sel, |
| 109 | + .list_voltage = regulator_list_voltage_table, |
| 110 | +}; |
| 111 | + |
| 112 | +static const struct regulator_desc stm32_vrefbuf_regu = { |
| 113 | + .name = "vref", |
| 114 | + .supply_name = "vdda", |
| 115 | + .volt_table = stm32_vrefbuf_voltages, |
| 116 | + .n_voltages = ARRAY_SIZE(stm32_vrefbuf_voltages), |
| 117 | + .ops = &stm32_vrefbuf_volt_ops, |
| 118 | + .type = REGULATOR_VOLTAGE, |
| 119 | + .owner = THIS_MODULE, |
| 120 | +}; |
| 121 | + |
| 122 | +static int stm32_vrefbuf_probe(struct platform_device *pdev) |
| 123 | +{ |
| 124 | + struct resource *res; |
| 125 | + struct stm32_vrefbuf *priv; |
| 126 | + struct regulator_config config = { }; |
| 127 | + struct regulator_dev *rdev; |
| 128 | + int ret; |
| 129 | + |
| 130 | + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); |
| 131 | + if (!priv) |
| 132 | + return -ENOMEM; |
| 133 | + |
| 134 | + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
| 135 | + priv->base = devm_ioremap_resource(&pdev->dev, res); |
| 136 | + if (IS_ERR(priv->base)) |
| 137 | + return PTR_ERR(priv->base); |
| 138 | + |
| 139 | + priv->clk = devm_clk_get(&pdev->dev, NULL); |
| 140 | + if (IS_ERR(priv->clk)) |
| 141 | + return PTR_ERR(priv->clk); |
| 142 | + |
| 143 | + ret = clk_prepare_enable(priv->clk); |
| 144 | + if (ret) { |
| 145 | + dev_err(&pdev->dev, "clk prepare failed with error %d\n", ret); |
| 146 | + return ret; |
| 147 | + } |
| 148 | + |
| 149 | + config.dev = &pdev->dev; |
| 150 | + config.driver_data = priv; |
| 151 | + config.of_node = pdev->dev.of_node; |
| 152 | + config.init_data = of_get_regulator_init_data(&pdev->dev, |
| 153 | + pdev->dev.of_node, |
| 154 | + &stm32_vrefbuf_regu); |
| 155 | + |
| 156 | + rdev = regulator_register(&stm32_vrefbuf_regu, &config); |
| 157 | + if (IS_ERR(rdev)) { |
| 158 | + ret = PTR_ERR(rdev); |
| 159 | + dev_err(&pdev->dev, "register failed with error %d\n", ret); |
| 160 | + goto err_clk_dis; |
| 161 | + } |
| 162 | + platform_set_drvdata(pdev, rdev); |
| 163 | + |
| 164 | + return 0; |
| 165 | + |
| 166 | +err_clk_dis: |
| 167 | + clk_disable_unprepare(priv->clk); |
| 168 | + |
| 169 | + return ret; |
| 170 | +} |
| 171 | + |
| 172 | +static int stm32_vrefbuf_remove(struct platform_device *pdev) |
| 173 | +{ |
| 174 | + struct regulator_dev *rdev = platform_get_drvdata(pdev); |
| 175 | + struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev); |
| 176 | + |
| 177 | + regulator_unregister(rdev); |
| 178 | + clk_disable_unprepare(priv->clk); |
| 179 | + |
| 180 | + return 0; |
| 181 | +}; |
| 182 | + |
| 183 | +static const struct of_device_id stm32_vrefbuf_of_match[] = { |
| 184 | + { .compatible = "st,stm32-vrefbuf", }, |
| 185 | + {}, |
| 186 | +}; |
| 187 | +MODULE_DEVICE_TABLE(of, stm32_vrefbuf_of_match); |
| 188 | + |
| 189 | +static struct platform_driver stm32_vrefbuf_driver = { |
| 190 | + .probe = stm32_vrefbuf_probe, |
| 191 | + .remove = stm32_vrefbuf_remove, |
| 192 | + .driver = { |
| 193 | + .name = "stm32-vrefbuf", |
| 194 | + .of_match_table = of_match_ptr(stm32_vrefbuf_of_match), |
| 195 | + }, |
| 196 | +}; |
| 197 | +module_platform_driver(stm32_vrefbuf_driver); |
| 198 | + |
| 199 | +MODULE_LICENSE("GPL v2"); |
| 200 | +MODULE_AUTHOR( "Fabrice Gasnier <[email protected]>"); |
| 201 | +MODULE_DESCRIPTION("STMicroelectronics STM32 VREFBUF driver"); |
| 202 | +MODULE_ALIAS("platform:stm32-vrefbuf"); |
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