drivers/reset/reset-brcmstb.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Broadcom STB generic reset controller for SW_INIT style reset controller
   4  *
   5  * Author: Florian Fainelli <f.fainelli@gmail.com>
   6  * Copyright (C) 2018 Broadcom
   7  */
   8 #include <linux/delay.h>
   9 #include <linux/device.h>
  10 #include <linux/io.h>
  11 #include <linux/module.h>
  12 #include <linux/of.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/reset-controller.h>
  15 #include <linux/types.h>
  16
  17 struct brcmstb_reset {
  18         void __iomem *base;
  19         struct reset_controller_dev rcdev;
  20 };
  21
  22 #define SW_INIT_SET             0x00
  23 #define SW_INIT_CLEAR           0x04
  24 #define SW_INIT_STATUS          0x08
  25
  26 #define SW_INIT_BIT(id)         BIT((id) & 0x1f)
  27 #define SW_INIT_BANK(id)        ((id) >> 5)
  28
  29 /* A full bank contains extra registers that we are not utilizing but still
  30  * qualify as a single bank.
  31  */
  32 #define SW_INIT_BANK_SIZE       0x18
  33
  34 static inline
  35 struct brcmstb_reset *to_brcmstb(struct reset_controller_dev *rcdev)
  36 {
  37         return container_of(rcdev, struct brcmstb_reset, rcdev);
  38 }
  39
  40 static int brcmstb_reset_assert(struct reset_controller_dev *rcdev,
  41                                 unsigned long id)
  42 {
  43         unsigned int off = SW_INIT_BANK(id) * SW_INIT_BANK_SIZE;
  44         struct brcmstb_reset *priv = to_brcmstb(rcdev);
  45
  46         writel_relaxed(SW_INIT_BIT(id), priv->base + off + SW_INIT_SET);
  47
  48         return 0;
  49 }
  50
  51 static int brcmstb_reset_deassert(struct reset_controller_dev *rcdev,
  52                                   unsigned long id)
  53 {
  54         unsigned int off = SW_INIT_BANK(id) * SW_INIT_BANK_SIZE;
  55         struct brcmstb_reset *priv = to_brcmstb(rcdev);
  56
  57         writel_relaxed(SW_INIT_BIT(id), priv->base + off + SW_INIT_CLEAR);
  58         /* Maximum reset delay after de-asserting a line and seeing block
  59          * operation is typically 14us for the worst case, build some slack
  60          * here.
  61          */
  62         usleep_range(100, 200);
  63
  64         return 0;
  65 }
  66
  67 static int brcmstb_reset_status(struct reset_controller_dev *rcdev,
  68                                 unsigned long id)
  69 {
  70         unsigned int off = SW_INIT_BANK(id) * SW_INIT_BANK_SIZE;
  71         struct brcmstb_reset *priv = to_brcmstb(rcdev);
  72
  73         return readl_relaxed(priv->base + off + SW_INIT_STATUS) &
  74                              SW_INIT_BIT(id);
  75 }
  76
  77 static const struct reset_control_ops brcmstb_reset_ops = {
  78         .assert = brcmstb_reset_assert,
  79         .deassert = brcmstb_reset_deassert,
  80         .status = brcmstb_reset_status,
  81 };
  82
  83 static int brcmstb_reset_probe(struct platform_device *pdev)
  84 {
  85         struct device *kdev = &pdev->dev;
  86         struct brcmstb_reset *priv;
  87         struct resource *res;
  88
  89         priv = devm_kzalloc(kdev, sizeof(*priv), GFP_KERNEL);
  90         if (!priv)
  91                 return -ENOMEM;
  92
  93         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  94         if (!IS_ALIGNED(res->start, SW_INIT_BANK_SIZE) ||
  95             !IS_ALIGNED(resource_size(res), SW_INIT_BANK_SIZE)) {
  96                 dev_err(kdev, "incorrect register range\n");
  97                 return -EINVAL;
  98         }
  99
 100         priv->base = devm_ioremap_resource(kdev, res);
 101         if (IS_ERR(priv->base))
 102                 return PTR_ERR(priv->base);
 103
 104         dev_set_drvdata(kdev, priv);
 105
 106         priv->rcdev.owner = THIS_MODULE;
 107         priv->rcdev.nr_resets = DIV_ROUND_DOWN_ULL(resource_size(res),
 108                                                    SW_INIT_BANK_SIZE) * 32;
 109         priv->rcdev.ops = &brcmstb_reset_ops;
 110         priv->rcdev.of_node = kdev->of_node;
 111         /* Use defaults: 1 cell and simple xlate function */
 112
 113         return devm_reset_controller_register(kdev, &priv->rcdev);
 114 }
 115
 116 static const struct of_device_id brcmstb_reset_of_match[] = {
 117         { .compatible = "brcm,brcmstb-reset" },
 118         { /* sentinel */ }
 119 };
 120
 121 static struct platform_driver brcmstb_reset_driver = {
 122         .probe  = brcmstb_reset_probe,
 123         .driver = {
 124                 .name = "brcmstb-reset",
 125                 .of_match_table = brcmstb_reset_of_match,
 126         },
 127 };
 128 module_platform_driver(brcmstb_reset_driver);
 129
 130 MODULE_AUTHOR("Broadcom");
 131 MODULE_DESCRIPTION("Broadcom STB reset controller");
 132 MODULE_LICENSE("GPL");