Quelle  stm32-vrefbuf.c   Sprache: C

// 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_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_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_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_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_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_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 void 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);
};

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 ");
MODULE_DESCRIPTION("STMicroelectronics STM32 VREFBUF driver");
MODULE_ALIAS("platform:stm32-vrefbuf");