LXR linux/drivers/mfd/stm32-lptimer.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * STM32 Low-Power Timer parent driver.
   4 * Copyright (C) STMicroelectronics 2017
   5 * Author: Fabrice Gasnier <fabrice.gasnier@st.com>
   6 * Inspired by Benjamin Gaignard's stm32-timers driver
   7 */
   8
   9#include <linux/mfd/stm32-lptimer.h>
  10#include <linux/module.h>
  11#include <linux/of_platform.h>
  12
  13#define STM32_LPTIM_MAX_REGISTER        0x3fc
  14
  15static const struct regmap_config stm32_lptimer_regmap_cfg = {
  16        .reg_bits = 32,
  17        .val_bits = 32,
  18        .reg_stride = sizeof(u32),
  19        .max_register = STM32_LPTIM_MAX_REGISTER,
  20};
  21
  22static int stm32_lptimer_detect_encoder(struct stm32_lptimer *ddata)
  23{
  24        u32 val;
  25        int ret;
  26
  27        /*
  28         * Quadrature encoder mode bit can only be written and read back when
  29         * Low-Power Timer supports it.
  30         */
  31        ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,
  32                                 STM32_LPTIM_ENC, STM32_LPTIM_ENC);
  33        if (ret)
  34                return ret;
  35
  36        ret = regmap_read(ddata->regmap, STM32_LPTIM_CFGR, &val);
  37        if (ret)
  38                return ret;
  39
  40        ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,
  41                                 STM32_LPTIM_ENC, 0);
  42        if (ret)
  43                return ret;
  44
  45        ddata->has_encoder = !!(val & STM32_LPTIM_ENC);
  46
  47        return 0;
  48}
  49
  50static int stm32_lptimer_probe(struct platform_device *pdev)
  51{
  52        struct device *dev = &pdev->dev;
  53        struct stm32_lptimer *ddata;
  54        struct resource *res;
  55        void __iomem *mmio;
  56        int ret;
  57
  58        ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
  59        if (!ddata)
  60                return -ENOMEM;
  61
  62        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  63        mmio = devm_ioremap_resource(dev, res);
  64        if (IS_ERR(mmio))
  65                return PTR_ERR(mmio);
  66
  67        ddata->regmap = devm_regmap_init_mmio_clk(dev, "mux", mmio,
  68                                                  &stm32_lptimer_regmap_cfg);
  69        if (IS_ERR(ddata->regmap))
  70                return PTR_ERR(ddata->regmap);
  71
  72        ddata->clk = devm_clk_get(dev, NULL);
  73        if (IS_ERR(ddata->clk))
  74                return PTR_ERR(ddata->clk);
  75
  76        ret = stm32_lptimer_detect_encoder(ddata);
  77        if (ret)
  78                return ret;
  79
  80        platform_set_drvdata(pdev, ddata);
  81
  82        return devm_of_platform_populate(&pdev->dev);
  83}
  84
  85static const struct of_device_id stm32_lptimer_of_match[] = {
  86        { .compatible = "st,stm32-lptimer", },
  87        {},
  88};
  89MODULE_DEVICE_TABLE(of, stm32_lptimer_of_match);
  90
  91static struct platform_driver stm32_lptimer_driver = {
  92        .probe = stm32_lptimer_probe,
  93        .driver = {
  94                .name = "stm32-lptimer",
  95                .of_match_table = stm32_lptimer_of_match,
  96        },
  97};
  98module_platform_driver(stm32_lptimer_driver);
  99
 100MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
 101MODULE_DESCRIPTION("STMicroelectronics STM32 Low-Power Timer");
 102MODULE_ALIAS("platform:stm32-lptimer");
 103MODULE_LICENSE("GPL v2");
 104