drivers/reset/reset-brcmstb.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Broadcom STB generic reset controller for SW_INIT style reset controller
0004  *
0005  * Author: Florian Fainelli <f.fainelli@gmail.com>
0006  * Copyright (C) 2018 Broadcom
0007  */
0008 #include <linux/delay.h>
0009 #include <linux/device.h>
0010 #include <linux/io.h>
0011 #include <linux/module.h>
0012 #include <linux/of.h>
0013 #include <linux/platform_device.h>
0014 #include <linux/reset-controller.h>
0015 #include <linux/types.h>
0016
0017 struct brcmstb_reset {
0018     void __iomem *base;
0019     struct reset_controller_dev rcdev;
0020 };
0021
0022 #define SW_INIT_SET     0x00
0023 #define SW_INIT_CLEAR       0x04
0024 #define SW_INIT_STATUS      0x08
0025
0026 #define SW_INIT_BIT(id)     BIT((id) & 0x1f)
0027 #define SW_INIT_BANK(id)    ((id) >> 5)
0028
0029 /* A full bank contains extra registers that we are not utilizing but still
0030  * qualify as a single bank.
0031  */
0032 #define SW_INIT_BANK_SIZE   0x18
0033
0034 static inline
0035 struct brcmstb_reset *to_brcmstb(struct reset_controller_dev *rcdev)
0036 {
0037     return container_of(rcdev, struct brcmstb_reset, rcdev);
0038 }
0039
0040 static int brcmstb_reset_assert(struct reset_controller_dev *rcdev,
0041                 unsigned long id)
0042 {
0043     unsigned int off = SW_INIT_BANK(id) * SW_INIT_BANK_SIZE;
0044     struct brcmstb_reset *priv = to_brcmstb(rcdev);
0045
0046     writel_relaxed(SW_INIT_BIT(id), priv->base + off + SW_INIT_SET);
0047
0048     return 0;
0049 }
0050
0051 static int brcmstb_reset_deassert(struct reset_controller_dev *rcdev,
0052                   unsigned long id)
0053 {
0054     unsigned int off = SW_INIT_BANK(id) * SW_INIT_BANK_SIZE;
0055     struct brcmstb_reset *priv = to_brcmstb(rcdev);
0056
0057     writel_relaxed(SW_INIT_BIT(id), priv->base + off + SW_INIT_CLEAR);
0058     /* Maximum reset delay after de-asserting a line and seeing block
0059      * operation is typically 14us for the worst case, build some slack
0060      * here.
0061      */
0062     usleep_range(100, 200);
0063
0064     return 0;
0065 }
0066
0067 static int brcmstb_reset_status(struct reset_controller_dev *rcdev,
0068                 unsigned long id)
0069 {
0070     unsigned int off = SW_INIT_BANK(id) * SW_INIT_BANK_SIZE;
0071     struct brcmstb_reset *priv = to_brcmstb(rcdev);
0072
0073     return readl_relaxed(priv->base + off + SW_INIT_STATUS) &
0074                  SW_INIT_BIT(id);
0075 }
0076
0077 static const struct reset_control_ops brcmstb_reset_ops = {
0078     .assert = brcmstb_reset_assert,
0079     .deassert = brcmstb_reset_deassert,
0080     .status = brcmstb_reset_status,
0081 };
0082
0083 static int brcmstb_reset_probe(struct platform_device *pdev)
0084 {
0085     struct device *kdev = &pdev->dev;
0086     struct brcmstb_reset *priv;
0087     struct resource *res;
0088
0089     priv = devm_kzalloc(kdev, sizeof(*priv), GFP_KERNEL);
0090     if (!priv)
0091         return -ENOMEM;
0092
0093     res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
0094     priv->base = devm_ioremap_resource(kdev, res);
0095     if (IS_ERR(priv->base))
0096         return PTR_ERR(priv->base);
0097
0098     dev_set_drvdata(kdev, priv);
0099
0100     priv->rcdev.owner = THIS_MODULE;
0101     priv->rcdev.nr_resets = DIV_ROUND_DOWN_ULL(resource_size(res),
0102                            SW_INIT_BANK_SIZE) * 32;
0103     priv->rcdev.ops = &brcmstb_reset_ops;
0104     priv->rcdev.of_node = kdev->of_node;
0105     /* Use defaults: 1 cell and simple xlate function */
0106
0107     return devm_reset_controller_register(kdev, &priv->rcdev);
0108 }
0109
0110 static const struct of_device_id brcmstb_reset_of_match[] = {
0111     { .compatible = "brcm,brcmstb-reset" },
0112     { /* sentinel */ }
0113 };
0114 MODULE_DEVICE_TABLE(of, brcmstb_reset_of_match);
0115
0116 static struct platform_driver brcmstb_reset_driver = {
0117     .probe  = brcmstb_reset_probe,
0118     .driver = {
0119         .name = "brcmstb-reset",
0120         .of_match_table = brcmstb_reset_of_match,
0121     },
0122 };
0123 module_platform_driver(brcmstb_reset_driver);
0124
0125 MODULE_AUTHOR("Broadcom");
0126 MODULE_DESCRIPTION("Broadcom STB reset controller");
0127 MODULE_LICENSE("GPL");