drivers/clk/sunxi-ng/ccu_reset.c

   1 /*
   2  * Copyright (C) 2016 Maxime Ripard
   3  * Maxime Ripard <maxime.ripard@free-electrons.com>
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation; either version 2 of
   8  * the License, or (at your option) any later version.
   9  */
  10
  11 #include <linux/delay.h>
  12 #include <linux/io.h>
  13 #include <linux/reset-controller.h>
  14
  15 #include "ccu_reset.h"
  16
  17 static int ccu_reset_assert(struct reset_controller_dev *rcdev,
  18                             unsigned long id)
  19 {
  20         struct ccu_reset *ccu = rcdev_to_ccu_reset(rcdev);
  21         const struct ccu_reset_map *map = &ccu->reset_map[id];
  22         unsigned long flags;
  23         u32 reg;
  24
  25         spin_lock_irqsave(ccu->lock, flags);
  26
  27         reg = readl(ccu->base + map->reg);
  28         writel(reg & ~map->bit, ccu->base + map->reg);
  29
  30         spin_unlock_irqrestore(ccu->lock, flags);
  31
  32         return 0;
  33 }
  34
  35 static int ccu_reset_deassert(struct reset_controller_dev *rcdev,
  36                               unsigned long id)
  37 {
  38         struct ccu_reset *ccu = rcdev_to_ccu_reset(rcdev);
  39         const struct ccu_reset_map *map = &ccu->reset_map[id];
  40         unsigned long flags;
  41         u32 reg;
  42
  43         spin_lock_irqsave(ccu->lock, flags);
  44
  45         reg = readl(ccu->base + map->reg);
  46         writel(reg | map->bit, ccu->base + map->reg);
  47
  48         spin_unlock_irqrestore(ccu->lock, flags);
  49
  50         return 0;
  51 }
  52
  53 static int ccu_reset_reset(struct reset_controller_dev *rcdev,
  54                            unsigned long id)
  55 {
  56         ccu_reset_assert(rcdev, id);
  57         udelay(10);
  58         ccu_reset_deassert(rcdev, id);
  59
  60         return 0;
  61 }
  62
  63 static int ccu_reset_status(struct reset_controller_dev *rcdev,
  64                             unsigned long id)
  65 {
  66         struct ccu_reset *ccu = rcdev_to_ccu_reset(rcdev);
  67         const struct ccu_reset_map *map = &ccu->reset_map[id];
  68
  69         /*
  70          * The reset control API expects 0 if reset is not asserted,
  71          * which is the opposite of what our hardware uses.
  72          */
  73         return !(map->bit & readl(ccu->base + map->reg));
  74 }
  75
  76 const struct reset_control_ops ccu_reset_ops = {
  77         .assert         = ccu_reset_assert,
  78         .deassert       = ccu_reset_deassert,
  79         .reset          = ccu_reset_reset,
  80         .status         = ccu_reset_status,
  81 };