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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!\n");
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\n", 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\n", 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");
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