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/mod_devicetable.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/reset-controller.h>
  23 #include <linux/reboot.h>
  24
  25 struct ath79_reset {
  26         struct reset_controller_dev rcdev;
  27         struct notifier_block restart_nb;
  28         void __iomem *base;
  29         spinlock_t lock;
  30 };
  31
  32 #define FULL_CHIP_RESET 24
  33
  34 static int ath79_reset_update(struct reset_controller_dev *rcdev,
  35                         unsigned long id, bool assert)
  36 {
  37         struct ath79_reset *ath79_reset =
  38                 container_of(rcdev, struct ath79_reset, rcdev);
  39         unsigned long flags;
  40         u32 val;
  41
  42         spin_lock_irqsave(&ath79_reset->lock, flags);
  43         val = readl(ath79_reset->base);
  44         if (assert)
  45                 val |= BIT(id);
  46         else
  47                 val &= ~BIT(id);
  48         writel(val, ath79_reset->base);
  49         spin_unlock_irqrestore(&ath79_reset->lock, flags);
  50
  51         return 0;
  52 }
  53
  54 static int ath79_reset_assert(struct reset_controller_dev *rcdev,
  55                         unsigned long id)
  56 {
  57         return ath79_reset_update(rcdev, id, true);
  58 }
  59
  60 static int ath79_reset_deassert(struct reset_controller_dev *rcdev,
  61                                 unsigned long id)
  62 {
  63         return ath79_reset_update(rcdev, id, false);
  64 }
  65
  66 static int ath79_reset_status(struct reset_controller_dev *rcdev,
  67                         unsigned long id)
  68 {
  69         struct ath79_reset *ath79_reset =
  70                 container_of(rcdev, struct ath79_reset, rcdev);
  71         u32 val;
  72
  73         val = readl(ath79_reset->base);
  74
  75         return !!(val & BIT(id));
  76 }
  77
  78 static const struct reset_control_ops ath79_reset_ops = {
  79         .assert = ath79_reset_assert,
  80         .deassert = ath79_reset_deassert,
  81         .status = ath79_reset_status,
  82 };
  83
  84 static int ath79_reset_restart_handler(struct notifier_block *nb,
  85                                 unsigned long action, void *data)
  86 {
  87         struct ath79_reset *ath79_reset =
  88                 container_of(nb, struct ath79_reset, restart_nb);
  89
  90         ath79_reset_assert(&ath79_reset->rcdev, FULL_CHIP_RESET);
  91
  92         return NOTIFY_DONE;
  93 }
  94
  95 static int ath79_reset_probe(struct platform_device *pdev)
  96 {
  97         struct ath79_reset *ath79_reset;
  98         struct resource *res;
  99         int err;
 100
 101         ath79_reset = devm_kzalloc(&pdev->dev,
 102                                 sizeof(*ath79_reset), GFP_KERNEL);
 103         if (!ath79_reset)
 104                 return -ENOMEM;
 105
 106         platform_set_drvdata(pdev, ath79_reset);
 107
 108         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 109         ath79_reset->base = devm_ioremap_resource(&pdev->dev, res);
 110         if (IS_ERR(ath79_reset->base))
 111                 return PTR_ERR(ath79_reset->base);
 112
 113         spin_lock_init(&ath79_reset->lock);
 114         ath79_reset->rcdev.ops = &ath79_reset_ops;
 115         ath79_reset->rcdev.owner = THIS_MODULE;
 116         ath79_reset->rcdev.of_node = pdev->dev.of_node;
 117         ath79_reset->rcdev.of_reset_n_cells = 1;
 118         ath79_reset->rcdev.nr_resets = 32;
 119
 120         err = devm_reset_controller_register(&pdev->dev, &ath79_reset->rcdev);
 121         if (err)
 122                 return err;
 123
 124         ath79_reset->restart_nb.notifier_call = ath79_reset_restart_handler;
 125         ath79_reset->restart_nb.priority = 128;
 126
 127         err = register_restart_handler(&ath79_reset->restart_nb);
 128         if (err)
 129                 dev_warn(&pdev->dev, "Failed to register restart handler\n");
 130
 131         return 0;
 132 }
 133
 134 static const struct of_device_id ath79_reset_dt_ids[] = {
 135         { .compatible = "qca,ar7100-reset", },
 136         { },
 137 };
 138
 139 static struct platform_driver ath79_reset_driver = {
 140         .probe  = ath79_reset_probe,
 141         .driver = {
 142                 .name                   = "ath79-reset",
 143                 .of_match_table         = ath79_reset_dt_ids,
 144                 .suppress_bind_attrs    = true,
 145         },
 146 };
 147 builtin_platform_driver(ath79_reset_driver);