drivers/regulator/stm32-vrefbuf.c

   1 /*
   2  * Copyright (C) STMicroelectronics 2017
   3  *
   4  * Author: Fabrice Gasnier <fabrice.gasnier@st.com>
   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 #include <linux/pm_runtime.h>
  19
  20 /* STM32 VREFBUF registers */
  21 #define STM32_VREFBUF_CSR               0x00
  22
  23 /* STM32 VREFBUF CSR bitfields */
  24 #define STM32_VRS                       GENMASK(6, 4)
  25 #define STM32_VRR                       BIT(3)
  26 #define STM32_HIZ                       BIT(1)
  27 #define STM32_ENVR                      BIT(0)
  28
  29 #define STM32_VREFBUF_AUTO_SUSPEND_DELAY_MS     10
  30
  31 struct stm32_vrefbuf {
  32         void __iomem *base;
  33         struct clk *clk;
  34         struct device *dev;
  35 };
  36
  37 static const unsigned int stm32_vrefbuf_voltages[] = {
  38         /* Matches resp. VRS = 000b, 001b, 010b, 011b */
  39         2500000, 2048000, 1800000, 1500000,
  40 };
  41
  42 static int stm32_vrefbuf_enable(struct regulator_dev *rdev)
  43 {
  44         struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
  45         u32 val;
  46         int ret;
  47
  48         ret = pm_runtime_get_sync(priv->dev);
  49         if (ret < 0) {
  50                 pm_runtime_put_noidle(priv->dev);
  51                 return ret;
  52         }
  53
  54         val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
  55         val = (val & ~STM32_HIZ) | STM32_ENVR;
  56         writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
  57
  58         /*
  59          * Vrefbuf startup time depends on external capacitor: wait here for
  60          * VRR to be set. That means output has reached expected value.
  61          * ~650us sleep should be enough for caps up to 1.5uF. Use 10ms as
  62          * arbitrary timeout.
  63          */
  64         ret = readl_poll_timeout(priv->base + STM32_VREFBUF_CSR, val,
  65                                  val & STM32_VRR, 650, 10000);
  66         if (ret) {
  67                 dev_err(&rdev->dev, "stm32 vrefbuf timed out!\n");
  68                 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
  69                 val = (val & ~STM32_ENVR) | STM32_HIZ;
  70                 writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
  71         }
  72
  73         pm_runtime_mark_last_busy(priv->dev);
  74         pm_runtime_put_autosuspend(priv->dev);
  75
  76         return ret;
  77 }
  78
  79 static int stm32_vrefbuf_disable(struct regulator_dev *rdev)
  80 {
  81         struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
  82         u32 val;
  83         int ret;
  84
  85         ret = pm_runtime_get_sync(priv->dev);
  86         if (ret < 0) {
  87                 pm_runtime_put_noidle(priv->dev);
  88                 return ret;
  89         }
  90
  91         val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
  92         val = (val & ~STM32_ENVR) | STM32_HIZ;
  93         writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
  94
  95         pm_runtime_mark_last_busy(priv->dev);
  96         pm_runtime_put_autosuspend(priv->dev);
  97
  98         return 0;
  99 }
 100
 101 static int stm32_vrefbuf_is_enabled(struct regulator_dev *rdev)
 102 {
 103         struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
 104         int ret;
 105
 106         ret = pm_runtime_get_sync(priv->dev);
 107         if (ret < 0) {
 108                 pm_runtime_put_noidle(priv->dev);
 109                 return ret;
 110         }
 111
 112         ret = readl_relaxed(priv->base + STM32_VREFBUF_CSR) & STM32_ENVR;
 113
 114         pm_runtime_mark_last_busy(priv->dev);
 115         pm_runtime_put_autosuspend(priv->dev);
 116
 117         return ret;
 118 }
 119
 120 static int stm32_vrefbuf_set_voltage_sel(struct regulator_dev *rdev,
 121                                          unsigned sel)
 122 {
 123         struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
 124         u32 val;
 125         int ret;
 126
 127         ret = pm_runtime_get_sync(priv->dev);
 128         if (ret < 0) {
 129                 pm_runtime_put_noidle(priv->dev);
 130                 return ret;
 131         }
 132
 133         val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
 134         val = (val & ~STM32_VRS) | FIELD_PREP(STM32_VRS, sel);
 135         writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
 136
 137         pm_runtime_mark_last_busy(priv->dev);
 138         pm_runtime_put_autosuspend(priv->dev);
 139
 140         return 0;
 141 }
 142
 143 static int stm32_vrefbuf_get_voltage_sel(struct regulator_dev *rdev)
 144 {
 145         struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
 146         u32 val;
 147         int ret;
 148
 149         ret = pm_runtime_get_sync(priv->dev);
 150         if (ret < 0) {
 151                 pm_runtime_put_noidle(priv->dev);
 152                 return ret;
 153         }
 154
 155         val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
 156         ret = FIELD_GET(STM32_VRS, val);
 157
 158         pm_runtime_mark_last_busy(priv->dev);
 159         pm_runtime_put_autosuspend(priv->dev);
 160
 161         return ret;
 162 }
 163
 164 static const struct regulator_ops stm32_vrefbuf_volt_ops = {
 165         .enable         = stm32_vrefbuf_enable,
 166         .disable        = stm32_vrefbuf_disable,
 167         .is_enabled     = stm32_vrefbuf_is_enabled,
 168         .get_voltage_sel = stm32_vrefbuf_get_voltage_sel,
 169         .set_voltage_sel = stm32_vrefbuf_set_voltage_sel,
 170         .list_voltage   = regulator_list_voltage_table,
 171 };
 172
 173 static const struct regulator_desc stm32_vrefbuf_regu = {
 174         .name = "vref",
 175         .supply_name = "vdda",
 176         .volt_table = stm32_vrefbuf_voltages,
 177         .n_voltages = ARRAY_SIZE(stm32_vrefbuf_voltages),
 178         .ops = &stm32_vrefbuf_volt_ops,
 179         .type = REGULATOR_VOLTAGE,
 180         .owner = THIS_MODULE,
 181 };
 182
 183 static int stm32_vrefbuf_probe(struct platform_device *pdev)
 184 {
 185         struct resource *res;
 186         struct stm32_vrefbuf *priv;
 187         struct regulator_config config = { };
 188         struct regulator_dev *rdev;
 189         int ret;
 190
 191         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 192         if (!priv)
 193                 return -ENOMEM;
 194         priv->dev = &pdev->dev;
 195
 196         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 197         priv->base = devm_ioremap_resource(&pdev->dev, res);
 198         if (IS_ERR(priv->base))
 199                 return PTR_ERR(priv->base);
 200
 201         priv->clk = devm_clk_get(&pdev->dev, NULL);
 202         if (IS_ERR(priv->clk))
 203                 return PTR_ERR(priv->clk);
 204
 205         pm_runtime_get_noresume(&pdev->dev);
 206         pm_runtime_set_active(&pdev->dev);
 207         pm_runtime_set_autosuspend_delay(&pdev->dev,
 208                                          STM32_VREFBUF_AUTO_SUSPEND_DELAY_MS);
 209         pm_runtime_use_autosuspend(&pdev->dev);
 210         pm_runtime_enable(&pdev->dev);
 211
 212         ret = clk_prepare_enable(priv->clk);
 213         if (ret) {
 214                 dev_err(&pdev->dev, "clk prepare failed with error %d\n", ret);
 215                 goto err_pm_stop;
 216         }
 217
 218         config.dev = &pdev->dev;
 219         config.driver_data = priv;
 220         config.of_node = pdev->dev.of_node;
 221         config.init_data = of_get_regulator_init_data(&pdev->dev,
 222                                                       pdev->dev.of_node,
 223                                                       &stm32_vrefbuf_regu);
 224
 225         rdev = regulator_register(&stm32_vrefbuf_regu, &config);
 226         if (IS_ERR(rdev)) {
 227                 ret = PTR_ERR(rdev);
 228                 dev_err(&pdev->dev, "register failed with error %d\n", ret);
 229                 goto err_clk_dis;
 230         }
 231         platform_set_drvdata(pdev, rdev);
 232
 233         pm_runtime_mark_last_busy(&pdev->dev);
 234         pm_runtime_put_autosuspend(&pdev->dev);
 235
 236         return 0;
 237
 238 err_clk_dis:
 239         clk_disable_unprepare(priv->clk);
 240 err_pm_stop:
 241         pm_runtime_disable(&pdev->dev);
 242         pm_runtime_set_suspended(&pdev->dev);
 243         pm_runtime_put_noidle(&pdev->dev);
 244
 245         return ret;
 246 }
 247
 248 static int stm32_vrefbuf_remove(struct platform_device *pdev)
 249 {
 250         struct regulator_dev *rdev = platform_get_drvdata(pdev);
 251         struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
 252
 253         pm_runtime_get_sync(&pdev->dev);
 254         regulator_unregister(rdev);
 255         clk_disable_unprepare(priv->clk);
 256         pm_runtime_disable(&pdev->dev);
 257         pm_runtime_set_suspended(&pdev->dev);
 258         pm_runtime_put_noidle(&pdev->dev);
 259
 260         return 0;
 261 };
 262
 263 static int __maybe_unused stm32_vrefbuf_runtime_suspend(struct device *dev)
 264 {
 265         struct regulator_dev *rdev = dev_get_drvdata(dev);
 266         struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
 267
 268         clk_disable_unprepare(priv->clk);
 269
 270         return 0;
 271 }
 272
 273 static int __maybe_unused stm32_vrefbuf_runtime_resume(struct device *dev)
 274 {
 275         struct regulator_dev *rdev = dev_get_drvdata(dev);
 276         struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
 277
 278         return clk_prepare_enable(priv->clk);
 279 }
 280
 281 static const struct dev_pm_ops stm32_vrefbuf_pm_ops = {
 282         SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
 283                                 pm_runtime_force_resume)
 284         SET_RUNTIME_PM_OPS(stm32_vrefbuf_runtime_suspend,
 285                            stm32_vrefbuf_runtime_resume,
 286                            NULL)
 287 };
 288
 289 static const struct of_device_id stm32_vrefbuf_of_match[] = {
 290         { .compatible = "st,stm32-vrefbuf", },
 291         {},
 292 };
 293 MODULE_DEVICE_TABLE(of, stm32_vrefbuf_of_match);
 294
 295 static struct platform_driver stm32_vrefbuf_driver = {
 296         .probe = stm32_vrefbuf_probe,
 297         .remove = stm32_vrefbuf_remove,
 298         .driver = {
 299                 .name  = "stm32-vrefbuf",
 300                 .of_match_table = of_match_ptr(stm32_vrefbuf_of_match),
 301                 .pm = &stm32_vrefbuf_pm_ops,
 302         },
 303 };
 304 module_platform_driver(stm32_vrefbuf_driver);
 305
 306 MODULE_LICENSE("GPL v2");
 307 MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
 308 MODULE_DESCRIPTION("STMicroelectronics STM32 VREFBUF driver");
 309 MODULE_ALIAS("platform:stm32-vrefbuf");