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 #include <linux/platform_device.h>
  13
  14 #define STM32_LPTIM_MAX_REGISTER        0x3fc
  15
  16 static const struct regmap_config stm32_lptimer_regmap_cfg = {
  17         .reg_bits = 32,
  18         .val_bits = 32,
  19         .reg_stride = sizeof(u32),
  20         .max_register = STM32_LPTIM_MAX_REGISTER,
  21         .fast_io = true,
  22 };
  23
  24 static int stm32_lptimer_detect_encoder(struct stm32_lptimer *ddata)
  25 {
  26         u32 val;
  27         int ret;
  28
  29         /*
  30          * Quadrature encoder mode bit can only be written and read back when
  31          * Low-Power Timer supports it.
  32          */
  33         ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,
  34                                  STM32_LPTIM_ENC, STM32_LPTIM_ENC);
  35         if (ret)
  36                 return ret;
  37
  38         ret = regmap_read(ddata->regmap, STM32_LPTIM_CFGR, &val);
  39         if (ret)
  40                 return ret;
  41
  42         ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,
  43                                  STM32_LPTIM_ENC, 0);
  44         if (ret)
  45                 return ret;
  46
  47         ddata->has_encoder = !!(val & STM32_LPTIM_ENC);
  48
  49         return 0;
  50 }
  51
  52 static int stm32_lptimer_probe(struct platform_device *pdev)
  53 {
  54         struct device *dev = &pdev->dev;
  55         struct stm32_lptimer *ddata;
  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         mmio = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
  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
  85 static const struct of_device_id stm32_lptimer_of_match[] = {
  86         { .compatible = "st,stm32-lptimer", },
  87         {},
  88 };
  89 MODULE_DEVICE_TABLE(of, stm32_lptimer_of_match);
  90
  91 static 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 };
  98 module_platform_driver(stm32_lptimer_driver);
  99
 100 MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
 101 MODULE_DESCRIPTION("STMicroelectronics STM32 Low-Power Timer");
 102 MODULE_ALIAS("platform:stm32-lptimer");
 103 MODULE_LICENSE("GPL v2");