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        .fast_io = true,
  21};
  22
  23static int stm32_lptimer_detect_encoder(struct stm32_lptimer *ddata)
  24{
  25        u32 val;
  26        int ret;
  27
  28        /*
  29         * Quadrature encoder mode bit can only be written and read back when
  30         * Low-Power Timer supports it.
  31         */
  32        ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,
  33                                 STM32_LPTIM_ENC, STM32_LPTIM_ENC);
  34        if (ret)
  35                return ret;
  36
  37        ret = regmap_read(ddata->regmap, STM32_LPTIM_CFGR, &val);
  38        if (ret)
  39                return ret;
  40
  41        ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,
  42                                 STM32_LPTIM_ENC, 0);
  43        if (ret)
  44                return ret;
  45
  46        ddata->has_encoder = !!(val & STM32_LPTIM_ENC);
  47
  48        return 0;
  49}
  50
  51static int stm32_lptimer_probe(struct platform_device *pdev)
  52{
  53        struct device *dev = &pdev->dev;
  54        struct stm32_lptimer *ddata;
  55        struct resource *res;
  56        void __iomem *mmio;
  57        int ret;
  58
  59        ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
  60        if (!ddata)
  61                return -ENOMEM;
  62
  63        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  64        mmio = devm_ioremap_resource(dev, res);
  65        if (IS_ERR(mmio))
  66                return PTR_ERR(mmio);
  67
  68        ddata->regmap = devm_regmap_init_mmio_clk(dev, "mux", mmio,
  69                                                  &stm32_lptimer_regmap_cfg);
  70        if (IS_ERR(ddata->regmap))
  71                return PTR_ERR(ddata->regmap);
  72
  73        ddata->clk = devm_clk_get(dev, NULL);
  74        if (IS_ERR(ddata->clk))
  75                return PTR_ERR(ddata->clk);
  76
  77        ret = stm32_lptimer_detect_encoder(ddata);
  78        if (ret)
  79                return ret;
  80
  81        platform_set_drvdata(pdev, ddata);
  82
  83        return devm_of_platform_populate(&pdev->dev);
  84}
  85
  86static const struct of_device_id stm32_lptimer_of_match[] = {
  87        { .compatible = "st,stm32-lptimer", },
  88        {},
  89};
  90MODULE_DEVICE_TABLE(of, stm32_lptimer_of_match);
  91
  92static struct platform_driver stm32_lptimer_driver = {
  93        .probe = stm32_lptimer_probe,
  94        .driver = {
  95                .name = "stm32-lptimer",
  96                .of_match_table = stm32_lptimer_of_match,
  97        },
  98};
  99module_platform_driver(stm32_lptimer_driver);
 100
 101MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
 102MODULE_DESCRIPTION("STMicroelectronics STM32 Low-Power Timer");
 103MODULE_ALIAS("platform:stm32-lptimer");
 104MODULE_LICENSE("GPL v2");
 105