drivers/reset/reset-stm32.c

   1 /*
   2  * Copyright (C) Maxime Coquelin 2015
   3  * Author:  Maxime Coquelin <mcoquelin.stm32@gmail.com>
   4  * License terms:  GNU General Public License (GPL), version 2
   5  *
   6  * Heavily based on sunxi driver from Maxime Ripard.
   7  */
   8
   9 #include <linux/err.h>
  10 #include <linux/io.h>
  11 #include <linux/of.h>
  12 #include <linux/of_address.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/reset-controller.h>
  15 #include <linux/slab.h>
  16 #include <linux/spinlock.h>
  17 #include <linux/types.h>
  18
  19 struct stm32_reset_data {
  20         spinlock_t                      lock;
  21         void __iomem                    *membase;
  22         struct reset_controller_dev     rcdev;
  23 };
  24
  25 static int stm32_reset_assert(struct reset_controller_dev *rcdev,
  26                               unsigned long id)
  27 {
  28         struct stm32_reset_data *data = container_of(rcdev,
  29                                                      struct stm32_reset_data,
  30                                                      rcdev);
  31         int bank = id / BITS_PER_LONG;
  32         int offset = id % BITS_PER_LONG;
  33         unsigned long flags;
  34         u32 reg;
  35
  36         spin_lock_irqsave(&data->lock, flags);
  37
  38         reg = readl(data->membase + (bank * 4));
  39         writel(reg | BIT(offset), data->membase + (bank * 4));
  40
  41         spin_unlock_irqrestore(&data->lock, flags);
  42
  43         return 0;
  44 }
  45
  46 static int stm32_reset_deassert(struct reset_controller_dev *rcdev,
  47                                 unsigned long id)
  48 {
  49         struct stm32_reset_data *data = container_of(rcdev,
  50                                                      struct stm32_reset_data,
  51                                                      rcdev);
  52         int bank = id / BITS_PER_LONG;
  53         int offset = id % BITS_PER_LONG;
  54         unsigned long flags;
  55         u32 reg;
  56
  57         spin_lock_irqsave(&data->lock, flags);
  58
  59         reg = readl(data->membase + (bank * 4));
  60         writel(reg & ~BIT(offset), data->membase + (bank * 4));
  61
  62         spin_unlock_irqrestore(&data->lock, flags);
  63
  64         return 0;
  65 }
  66
  67 static const struct reset_control_ops stm32_reset_ops = {
  68         .assert         = stm32_reset_assert,
  69         .deassert       = stm32_reset_deassert,
  70 };
  71
  72 static const struct of_device_id stm32_reset_dt_ids[] = {
  73          { .compatible = "st,stm32-rcc", },
  74          { /* sentinel */ },
  75 };
  76
  77 static int stm32_reset_probe(struct platform_device *pdev)
  78 {
  79         struct stm32_reset_data *data;
  80         struct resource *res;
  81
  82         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
  83         if (!data)
  84                 return -ENOMEM;
  85
  86         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  87         data->membase = devm_ioremap_resource(&pdev->dev, res);
  88         if (IS_ERR(data->membase))
  89                 return PTR_ERR(data->membase);
  90
  91         spin_lock_init(&data->lock);
  92
  93         data->rcdev.owner = THIS_MODULE;
  94         data->rcdev.nr_resets = resource_size(res) * 8;
  95         data->rcdev.ops = &stm32_reset_ops;
  96         data->rcdev.of_node = pdev->dev.of_node;
  97
  98         return devm_reset_controller_register(&pdev->dev, &data->rcdev);
  99 }
 100
 101 static struct platform_driver stm32_reset_driver = {
 102         .probe  = stm32_reset_probe,
 103         .driver = {
 104                 .name           = "stm32-rcc-reset",
 105                 .of_match_table = stm32_reset_dt_ids,
 106         },
 107 };
 108 builtin_platform_driver(stm32_reset_driver);