drivers/reset/reset-bcm6345.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * BCM6345 Reset Controller Driver
   4  *
   5  * Copyright (C) 2020 Álvaro Fernández Rojas <noltari@gmail.com>
   6  */
   7
   8 #include <linux/delay.h>
   9 #include <linux/init.h>
  10 #include <linux/io.h>
  11 #include <linux/mod_devicetable.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/reset-controller.h>
  14
  15 #define BCM6345_RESET_NUM               32
  16 #define BCM6345_RESET_SLEEP_MIN_US      10000
  17 #define BCM6345_RESET_SLEEP_MAX_US      20000
  18
  19 struct bcm6345_reset {
  20         struct reset_controller_dev rcdev;
  21         void __iomem *base;
  22         spinlock_t lock;
  23 };
  24
  25 static inline struct bcm6345_reset *
  26 to_bcm6345_reset(struct reset_controller_dev *rcdev)
  27 {
  28         return container_of(rcdev, struct bcm6345_reset, rcdev);
  29 }
  30
  31 static int bcm6345_reset_update(struct reset_controller_dev *rcdev,
  32                                 unsigned long id, bool assert)
  33 {
  34         struct bcm6345_reset *bcm6345_reset = to_bcm6345_reset(rcdev);
  35         unsigned long flags;
  36         uint32_t val;
  37
  38         spin_lock_irqsave(&bcm6345_reset->lock, flags);
  39         val = __raw_readl(bcm6345_reset->base);
  40         if (assert)
  41                 val &= ~BIT(id);
  42         else
  43                 val |= BIT(id);
  44         __raw_writel(val, bcm6345_reset->base);
  45         spin_unlock_irqrestore(&bcm6345_reset->lock, flags);
  46
  47         return 0;
  48 }
  49
  50 static int bcm6345_reset_assert(struct reset_controller_dev *rcdev,
  51                                 unsigned long id)
  52 {
  53         return bcm6345_reset_update(rcdev, id, true);
  54 }
  55
  56 static int bcm6345_reset_deassert(struct reset_controller_dev *rcdev,
  57                                   unsigned long id)
  58 {
  59         return bcm6345_reset_update(rcdev, id, false);
  60 }
  61
  62 static int bcm6345_reset_reset(struct reset_controller_dev *rcdev,
  63                                unsigned long id)
  64 {
  65         bcm6345_reset_update(rcdev, id, true);
  66         usleep_range(BCM6345_RESET_SLEEP_MIN_US,
  67                      BCM6345_RESET_SLEEP_MAX_US);
  68
  69         bcm6345_reset_update(rcdev, id, false);
  70         /*
  71          * Ensure component is taken out reset state by sleeping also after
  72          * deasserting the reset. Otherwise, the component may not be ready
  73          * for operation.
  74          */
  75         usleep_range(BCM6345_RESET_SLEEP_MIN_US,
  76                      BCM6345_RESET_SLEEP_MAX_US);
  77
  78         return 0;
  79 }
  80
  81 static int bcm6345_reset_status(struct reset_controller_dev *rcdev,
  82                                 unsigned long id)
  83 {
  84         struct bcm6345_reset *bcm6345_reset = to_bcm6345_reset(rcdev);
  85
  86         return !(__raw_readl(bcm6345_reset->base) & BIT(id));
  87 }
  88
  89 static const struct reset_control_ops bcm6345_reset_ops = {
  90         .assert = bcm6345_reset_assert,
  91         .deassert = bcm6345_reset_deassert,
  92         .reset = bcm6345_reset_reset,
  93         .status = bcm6345_reset_status,
  94 };
  95
  96 static int bcm6345_reset_probe(struct platform_device *pdev)
  97 {
  98         struct bcm6345_reset *bcm6345_reset;
  99
 100         bcm6345_reset = devm_kzalloc(&pdev->dev,
 101                                      sizeof(*bcm6345_reset), GFP_KERNEL);
 102         if (!bcm6345_reset)
 103                 return -ENOMEM;
 104
 105         platform_set_drvdata(pdev, bcm6345_reset);
 106
 107         bcm6345_reset->base = devm_platform_ioremap_resource(pdev, 0);
 108         if (IS_ERR(bcm6345_reset->base))
 109                 return PTR_ERR(bcm6345_reset->base);
 110
 111         spin_lock_init(&bcm6345_reset->lock);
 112         bcm6345_reset->rcdev.ops = &bcm6345_reset_ops;
 113         bcm6345_reset->rcdev.owner = THIS_MODULE;
 114         bcm6345_reset->rcdev.of_node = pdev->dev.of_node;
 115         bcm6345_reset->rcdev.of_reset_n_cells = 1;
 116         bcm6345_reset->rcdev.nr_resets = BCM6345_RESET_NUM;
 117
 118         return devm_reset_controller_register(&pdev->dev,
 119                                               &bcm6345_reset->rcdev);
 120 }
 121
 122 static const struct of_device_id bcm6345_reset_of_match[] = {
 123         { .compatible = "brcm,bcm6345-reset" },
 124         { /* sentinel */ },
 125 };
 126
 127 static struct platform_driver bcm6345_reset_driver = {
 128         .probe = bcm6345_reset_probe,
 129         .driver = {
 130                 .name = "bcm6345-reset",
 131                 .of_match_table = bcm6345_reset_of_match,
 132                 .suppress_bind_attrs = true,
 133         },
 134 };
 135 builtin_platform_driver(bcm6345_reset_driver);