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
  15 static 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
  23 static 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
  51 static 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
  86 static const struct of_device_id stm32_lptimer_of_match[] = {
  87         { .compatible = "st,stm32-lptimer", },
  88         {},
  89 };
  90 MODULE_DEVICE_TABLE(of, stm32_lptimer_of_match);
  91
  92 static 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 };
  99 module_platform_driver(stm32_lptimer_driver);
 100
 101 MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
 102 MODULE_DESCRIPTION("STMicroelectronics STM32 Low-Power Timer");
 103 MODULE_ALIAS("platform:stm32-lptimer");
 104 MODULE_LICENSE("GPL v2");