drivers/reset/reset-ath79.c

   1 /*
   2  * AR71xx Reset Controller Driver
   3  * Author: Alban Bedel
   4  *
   5  * Copyright (C) 2015 Alban Bedel <albeu@free.fr>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  */
  17
  18 #include <linux/io.h>
  19 #include <linux/init.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/reset-controller.h>
  22 #include <linux/reboot.h>
  23
  24 struct ath79_reset {
  25         struct reset_controller_dev rcdev;
  26         struct notifier_block restart_nb;
  27         void __iomem *base;
  28         spinlock_t lock;
  29 };
  30
  31 #define FULL_CHIP_RESET 24
  32
  33 static int ath79_reset_update(struct reset_controller_dev *rcdev,
  34                         unsigned long id, bool assert)
  35 {
  36         struct ath79_reset *ath79_reset =
  37                 container_of(rcdev, struct ath79_reset, rcdev);
  38         unsigned long flags;
  39         u32 val;
  40
  41         spin_lock_irqsave(&ath79_reset->lock, flags);
  42         val = readl(ath79_reset->base);
  43         if (assert)
  44                 val |= BIT(id);
  45         else
  46                 val &= ~BIT(id);
  47         writel(val, ath79_reset->base);
  48         spin_unlock_irqrestore(&ath79_reset->lock, flags);
  49
  50         return 0;
  51 }
  52
  53 static int ath79_reset_assert(struct reset_controller_dev *rcdev,
  54                         unsigned long id)
  55 {
  56         return ath79_reset_update(rcdev, id, true);
  57 }
  58
  59 static int ath79_reset_deassert(struct reset_controller_dev *rcdev,
  60                                 unsigned long id)
  61 {
  62         return ath79_reset_update(rcdev, id, false);
  63 }
  64
  65 static int ath79_reset_status(struct reset_controller_dev *rcdev,
  66                         unsigned long id)
  67 {
  68         struct ath79_reset *ath79_reset =
  69                 container_of(rcdev, struct ath79_reset, rcdev);
  70         u32 val;
  71
  72         val = readl(ath79_reset->base);
  73
  74         return !!(val & BIT(id));
  75 }
  76
  77 static const struct reset_control_ops ath79_reset_ops = {
  78         .assert = ath79_reset_assert,
  79         .deassert = ath79_reset_deassert,
  80         .status = ath79_reset_status,
  81 };
  82
  83 static int ath79_reset_restart_handler(struct notifier_block *nb,
  84                                 unsigned long action, void *data)
  85 {
  86         struct ath79_reset *ath79_reset =
  87                 container_of(nb, struct ath79_reset, restart_nb);
  88
  89         ath79_reset_assert(&ath79_reset->rcdev, FULL_CHIP_RESET);
  90
  91         return NOTIFY_DONE;
  92 }
  93
  94 static int ath79_reset_probe(struct platform_device *pdev)
  95 {
  96         struct ath79_reset *ath79_reset;
  97         struct resource *res;
  98         int err;
  99
 100         ath79_reset = devm_kzalloc(&pdev->dev,
 101                                 sizeof(*ath79_reset), GFP_KERNEL);
 102         if (!ath79_reset)
 103                 return -ENOMEM;
 104
 105         platform_set_drvdata(pdev, ath79_reset);
 106
 107         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 108         ath79_reset->base = devm_ioremap_resource(&pdev->dev, res);
 109         if (IS_ERR(ath79_reset->base))
 110                 return PTR_ERR(ath79_reset->base);
 111
 112         spin_lock_init(&ath79_reset->lock);
 113         ath79_reset->rcdev.ops = &ath79_reset_ops;
 114         ath79_reset->rcdev.owner = THIS_MODULE;
 115         ath79_reset->rcdev.of_node = pdev->dev.of_node;
 116         ath79_reset->rcdev.of_reset_n_cells = 1;
 117         ath79_reset->rcdev.nr_resets = 32;
 118
 119         err = devm_reset_controller_register(&pdev->dev, &ath79_reset->rcdev);
 120         if (err)
 121                 return err;
 122
 123         ath79_reset->restart_nb.notifier_call = ath79_reset_restart_handler;
 124         ath79_reset->restart_nb.priority = 128;
 125
 126         err = register_restart_handler(&ath79_reset->restart_nb);
 127         if (err)
 128                 dev_warn(&pdev->dev, "Failed to register restart handler\n");
 129
 130         return 0;
 131 }
 132
 133 static const struct of_device_id ath79_reset_dt_ids[] = {
 134         { .compatible = "qca,ar7100-reset", },
 135         { },
 136 };
 137
 138 static struct platform_driver ath79_reset_driver = {
 139         .probe  = ath79_reset_probe,
 140         .driver = {
 141                 .name                   = "ath79-reset",
 142                 .of_match_table         = ath79_reset_dt_ids,
 143                 .suppress_bind_attrs    = true,
 144         },
 145 };
 146 builtin_platform_driver(ath79_reset_driver);