drivers/reset/reset-brcmstb-rescal.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (C) 2018-2020 Broadcom */
   3
   4 #include <linux/device.h>
   5 #include <linux/iopoll.h>
   6 #include <linux/module.h>
   7 #include <linux/of.h>
   8 #include <linux/platform_device.h>
   9 #include <linux/reset-controller.h>
  10
  11 #define BRCM_RESCAL_START       0x0
  12 #define  BRCM_RESCAL_START_BIT  BIT(0)
  13 #define BRCM_RESCAL_CTRL        0x4
  14 #define BRCM_RESCAL_STATUS      0x8
  15 #define  BRCM_RESCAL_STATUS_BIT BIT(0)
  16
  17 struct brcm_rescal_reset {
  18         void __iomem *base;
  19         struct device *dev;
  20         struct reset_controller_dev rcdev;
  21 };
  22
  23 /* Also doubles a deassert */
  24 static int brcm_rescal_reset_set(struct reset_controller_dev *rcdev,
  25                                  unsigned long id)
  26 {
  27         struct brcm_rescal_reset *data =
  28                 container_of(rcdev, struct brcm_rescal_reset, rcdev);
  29         void __iomem *base = data->base;
  30         u32 reg;
  31         int ret;
  32
  33         reg = readl(base + BRCM_RESCAL_START);
  34         writel(reg | BRCM_RESCAL_START_BIT, base + BRCM_RESCAL_START);
  35         reg = readl(base + BRCM_RESCAL_START);
  36         if (!(reg & BRCM_RESCAL_START_BIT)) {
  37                 dev_err(data->dev, "failed to start SATA/PCIe rescal\n");
  38                 return -EIO;
  39         }
  40
  41         ret = readl_poll_timeout(base + BRCM_RESCAL_STATUS, reg,
  42                                  (reg & BRCM_RESCAL_STATUS_BIT), 100, 1000);
  43         if (ret) {
  44                 dev_err(data->dev, "time out on SATA/PCIe rescal\n");
  45                 return ret;
  46         }
  47
  48         reg = readl(base + BRCM_RESCAL_START);
  49         writel(reg & ~BRCM_RESCAL_START_BIT, base + BRCM_RESCAL_START);
  50
  51         dev_dbg(data->dev, "SATA/PCIe rescal success\n");
  52
  53         return 0;
  54 }
  55
  56 /* A dummy function - deassert/reset does all the work */
  57 static int brcm_rescal_reset_assert(struct reset_controller_dev *rcdev,
  58                                     unsigned long id)
  59 {
  60         return 0;
  61 }
  62
  63 static int brcm_rescal_reset_xlate(struct reset_controller_dev *rcdev,
  64                                    const struct of_phandle_args *reset_spec)
  65 {
  66         /* This is needed if #reset-cells == 0. */
  67         return 0;
  68 }
  69
  70 static const struct reset_control_ops brcm_rescal_reset_ops = {
  71         .reset = brcm_rescal_reset_set,
  72         .deassert = brcm_rescal_reset_set,
  73         .assert = brcm_rescal_reset_assert,
  74 };
  75
  76 static int brcm_rescal_reset_probe(struct platform_device *pdev)
  77 {
  78         struct brcm_rescal_reset *data;
  79
  80         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
  81         if (!data)
  82                 return -ENOMEM;
  83
  84         data->base = devm_platform_ioremap_resource(pdev, 0);
  85         if (IS_ERR(data->base))
  86                 return PTR_ERR(data->base);
  87
  88         data->rcdev.owner = THIS_MODULE;
  89         data->rcdev.nr_resets = 1;
  90         data->rcdev.ops = &brcm_rescal_reset_ops;
  91         data->rcdev.of_node = pdev->dev.of_node;
  92         data->rcdev.of_xlate = brcm_rescal_reset_xlate;
  93         data->dev = &pdev->dev;
  94
  95         return devm_reset_controller_register(&pdev->dev, &data->rcdev);
  96 }
  97
  98 static const struct of_device_id brcm_rescal_reset_of_match[] = {
  99         { .compatible = "brcm,bcm7216-pcie-sata-rescal" },
 100         { },
 101 };
 102 MODULE_DEVICE_TABLE(of, brcm_rescal_reset_of_match);
 103
 104 static struct platform_driver brcm_rescal_reset_driver = {
 105         .probe = brcm_rescal_reset_probe,
 106         .driver = {
 107                 .name   = "brcm-rescal-reset",
 108                 .of_match_table = brcm_rescal_reset_of_match,
 109         }
 110 };
 111 module_platform_driver(brcm_rescal_reset_driver);
 112
 113 MODULE_AUTHOR("Broadcom");
 114 MODULE_DESCRIPTION("Broadcom SATA/PCIe rescal reset controller");
 115 MODULE_LICENSE("GPL v2");