diff options
Diffstat (limited to 'drivers/regulator/stm32-vrefbuf.c')
| -rw-r--r-- | drivers/regulator/stm32-vrefbuf.c | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/drivers/regulator/stm32-vrefbuf.c b/drivers/regulator/stm32-vrefbuf.c new file mode 100644 index 000000000000..72c8b3e1022b --- /dev/null +++ b/drivers/regulator/stm32-vrefbuf.c @@ -0,0 +1,202 @@ +/* + * 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"); |