drivers/regulator/stm32-vrefbuf.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) STMicroelectronics 2017
   4  *
   5  * Author: Fabrice Gasnier <fabrice.gasnier@st.com>
   6  */
   7
   8 #include <linux/bitfield.h>
   9 #include <linux/clk.h>
  10 #include <linux/io.h>
  11 #include <linux/iopoll.h>
  12 #include <linux/module.h>
  13 #include <linux/of.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/regulator/driver.h>
  16 #include <linux/regulator/of_regulator.h>
  17 #include <linux/pm_runtime.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 #define STM32_VREFBUF_AUTO_SUSPEND_DELAY_MS     10
  29
  30 struct stm32_vrefbuf {
  31         void __iomem *base;
  32         struct clk *clk;
  33         struct device *dev;
  34 };
  35
  36 static const unsigned int stm32_vrefbuf_voltages[] = {
  37         /* Matches resp. VRS = 000b, 001b, 010b, 011b */
  38         2500000, 2048000, 1800000, 1500000,
  39 };
  40
  41 static int stm32_vrefbuf_enable(struct regulator_dev *rdev)
  42 {
  43         struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
  44         u32 val;
  45         int ret;
  46
  47         ret = pm_runtime_resume_and_get(priv->dev);
  48         if (ret < 0)
  49                 return ret;
  50
  51         val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
  52         val = (val & ~STM32_HIZ) | STM32_ENVR;
  53         writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
  54
  55         /*
  56          * Vrefbuf startup time depends on external capacitor: wait here for
  57          * VRR to be set. That means output has reached expected value.
  58          * ~650us sleep should be enough for caps up to 1.5uF. Use 10ms as
  59          * arbitrary timeout.
  60          */
  61         ret = readl_poll_timeout(priv->base + STM32_VREFBUF_CSR, val,
  62                                  val & STM32_VRR, 650, 10000);
  63         if (ret) {
  64                 dev_err(&rdev->dev, "stm32 vrefbuf timed out!\n");
  65                 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
  66                 val = (val & ~STM32_ENVR) | STM32_HIZ;
  67                 writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
  68         }
  69
  70         pm_runtime_mark_last_busy(priv->dev);
  71         pm_runtime_put_autosuspend(priv->dev);
  72
  73         return ret;
  74 }
  75
  76 static int stm32_vrefbuf_disable(struct regulator_dev *rdev)
  77 {
  78         struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
  79         u32 val;
  80         int ret;
  81
  82         ret = pm_runtime_resume_and_get(priv->dev);
  83         if (ret < 0)
  84                 return ret;
  85
  86         val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
  87         val &= ~STM32_ENVR;
  88         writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
  89
  90         pm_runtime_mark_last_busy(priv->dev);
  91         pm_runtime_put_autosuspend(priv->dev);
  92
  93         return 0;
  94 }
  95
  96 static int stm32_vrefbuf_is_enabled(struct regulator_dev *rdev)
  97 {
  98         struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
  99         int ret;
 100
 101         ret = pm_runtime_resume_and_get(priv->dev);
 102         if (ret < 0)
 103                 return ret;
 104
 105         ret = readl_relaxed(priv->base + STM32_VREFBUF_CSR) & STM32_ENVR;
 106
 107         pm_runtime_mark_last_busy(priv->dev);
 108         pm_runtime_put_autosuspend(priv->dev);
 109
 110         return ret;
 111 }
 112
 113 static int stm32_vrefbuf_set_voltage_sel(struct regulator_dev *rdev,
 114                                          unsigned sel)
 115 {
 116         struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
 117         u32 val;
 118         int ret;
 119
 120         ret = pm_runtime_resume_and_get(priv->dev);
 121         if (ret < 0)
 122                 return ret;
 123
 124         val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
 125         val = (val & ~STM32_VRS) | FIELD_PREP(STM32_VRS, sel);
 126         writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
 127
 128         pm_runtime_mark_last_busy(priv->dev);
 129         pm_runtime_put_autosuspend(priv->dev);
 130
 131         return 0;
 132 }
 133
 134 static int stm32_vrefbuf_get_voltage_sel(struct regulator_dev *rdev)
 135 {
 136         struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
 137         u32 val;
 138         int ret;
 139
 140         ret = pm_runtime_resume_and_get(priv->dev);
 141         if (ret < 0)
 142                 return ret;
 143
 144         val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
 145         ret = FIELD_GET(STM32_VRS, val);
 146
 147         pm_runtime_mark_last_busy(priv->dev);
 148         pm_runtime_put_autosuspend(priv->dev);
 149
 150         return ret;
 151 }
 152
 153 static const struct regulator_ops stm32_vrefbuf_volt_ops = {
 154         .enable         = stm32_vrefbuf_enable,
 155         .disable        = stm32_vrefbuf_disable,
 156         .is_enabled     = stm32_vrefbuf_is_enabled,
 157         .get_voltage_sel = stm32_vrefbuf_get_voltage_sel,
 158         .set_voltage_sel = stm32_vrefbuf_set_voltage_sel,
 159         .list_voltage   = regulator_list_voltage_table,
 160 };
 161
 162 static const struct regulator_desc stm32_vrefbuf_regu = {
 163         .name = "vref",
 164         .supply_name = "vdda",
 165         .volt_table = stm32_vrefbuf_voltages,
 166         .n_voltages = ARRAY_SIZE(stm32_vrefbuf_voltages),
 167         .ops = &stm32_vrefbuf_volt_ops,
 168         .off_on_delay = 1000,
 169         .type = REGULATOR_VOLTAGE,
 170         .owner = THIS_MODULE,
 171 };
 172
 173 static int stm32_vrefbuf_probe(struct platform_device *pdev)
 174 {
 175         struct stm32_vrefbuf *priv;
 176         struct regulator_config config = { };
 177         struct regulator_dev *rdev;
 178         int ret;
 179
 180         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 181         if (!priv)
 182                 return -ENOMEM;
 183         priv->dev = &pdev->dev;
 184
 185         priv->base = devm_platform_ioremap_resource(pdev, 0);
 186         if (IS_ERR(priv->base))
 187                 return PTR_ERR(priv->base);
 188
 189         priv->clk = devm_clk_get(&pdev->dev, NULL);
 190         if (IS_ERR(priv->clk))
 191                 return PTR_ERR(priv->clk);
 192
 193         pm_runtime_get_noresume(&pdev->dev);
 194         pm_runtime_set_active(&pdev->dev);
 195         pm_runtime_set_autosuspend_delay(&pdev->dev,
 196                                          STM32_VREFBUF_AUTO_SUSPEND_DELAY_MS);
 197         pm_runtime_use_autosuspend(&pdev->dev);
 198         pm_runtime_enable(&pdev->dev);
 199
 200         ret = clk_prepare_enable(priv->clk);
 201         if (ret) {
 202                 dev_err(&pdev->dev, "clk prepare failed with error %d\n", ret);
 203                 goto err_pm_stop;
 204         }
 205
 206         config.dev = &pdev->dev;
 207         config.driver_data = priv;
 208         config.of_node = pdev->dev.of_node;
 209         config.init_data = of_get_regulator_init_data(&pdev->dev,
 210                                                       pdev->dev.of_node,
 211                                                       &stm32_vrefbuf_regu);
 212
 213         rdev = regulator_register(&pdev->dev, &stm32_vrefbuf_regu, &config);
 214         if (IS_ERR(rdev)) {
 215                 ret = PTR_ERR(rdev);
 216                 dev_err(&pdev->dev, "register failed with error %d\n", ret);
 217                 goto err_clk_dis;
 218         }
 219         platform_set_drvdata(pdev, rdev);
 220
 221         pm_runtime_mark_last_busy(&pdev->dev);
 222         pm_runtime_put_autosuspend(&pdev->dev);
 223
 224         return 0;
 225
 226 err_clk_dis:
 227         clk_disable_unprepare(priv->clk);
 228 err_pm_stop:
 229         pm_runtime_disable(&pdev->dev);
 230         pm_runtime_set_suspended(&pdev->dev);
 231         pm_runtime_put_noidle(&pdev->dev);
 232
 233         return ret;
 234 }
 235
 236 static void stm32_vrefbuf_remove(struct platform_device *pdev)
 237 {
 238         struct regulator_dev *rdev = platform_get_drvdata(pdev);
 239         struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
 240
 241         pm_runtime_get_sync(&pdev->dev);
 242         regulator_unregister(rdev);
 243         clk_disable_unprepare(priv->clk);
 244         pm_runtime_disable(&pdev->dev);
 245         pm_runtime_set_suspended(&pdev->dev);
 246         pm_runtime_put_noidle(&pdev->dev);
 247 };
 248
 249 static int __maybe_unused stm32_vrefbuf_runtime_suspend(struct device *dev)
 250 {
 251         struct regulator_dev *rdev = dev_get_drvdata(dev);
 252         struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
 253
 254         clk_disable_unprepare(priv->clk);
 255
 256         return 0;
 257 }
 258
 259 static int __maybe_unused stm32_vrefbuf_runtime_resume(struct device *dev)
 260 {
 261         struct regulator_dev *rdev = dev_get_drvdata(dev);
 262         struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
 263
 264         return clk_prepare_enable(priv->clk);
 265 }
 266
 267 static const struct dev_pm_ops stm32_vrefbuf_pm_ops = {
 268         SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
 269                                 pm_runtime_force_resume)
 270         SET_RUNTIME_PM_OPS(stm32_vrefbuf_runtime_suspend,
 271                            stm32_vrefbuf_runtime_resume,
 272                            NULL)
 273 };
 274
 275 static const struct of_device_id __maybe_unused stm32_vrefbuf_of_match[] = {
 276         { .compatible = "st,stm32-vrefbuf", },
 277         {},
 278 };
 279 MODULE_DEVICE_TABLE(of, stm32_vrefbuf_of_match);
 280
 281 static struct platform_driver stm32_vrefbuf_driver = {
 282         .probe = stm32_vrefbuf_probe,
 283         .remove = stm32_vrefbuf_remove,
 284         .driver = {
 285                 .name  = "stm32-vrefbuf",
 286                 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
 287                 .of_match_table = of_match_ptr(stm32_vrefbuf_of_match),
 288                 .pm = &stm32_vrefbuf_pm_ops,
 289         },
 290 };
 291 module_platform_driver(stm32_vrefbuf_driver);
 292
 293 MODULE_LICENSE("GPL v2");
 294 MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
 295 MODULE_DESCRIPTION("STMicroelectronics STM32 VREFBUF driver");
 296 MODULE_ALIAS("platform:stm32-vrefbuf");