LXR linux/drivers/power/reset/brcm-kona-reset.c

   1/*
   2 * Copyright (C) 2016 Broadcom
   3 *
   4 * This program is free software; you can redistribute it and/or
   5 * modify it under the terms of the GNU General Public License as
   6 * published by the Free Software Foundation version 2.
   7 *
   8 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
   9 * kind, whether express or implied; without even the implied warranty
  10 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 * GNU General Public License for more details.
  12 */
  13
  14#include <linux/io.h>
  15#include <linux/of_address.h>
  16#include <linux/of_platform.h>
  17#include <linux/reboot.h>
  18
  19#define RSTMGR_REG_WR_ACCESS_OFFSET     0
  20#define RSTMGR_REG_CHIP_SOFT_RST_OFFSET 4
  21
  22#define RSTMGR_WR_PASSWORD              0xa5a5
  23#define RSTMGR_WR_PASSWORD_SHIFT        8
  24#define RSTMGR_WR_ACCESS_ENABLE         1
  25
  26static void __iomem *kona_reset_base;
  27
  28static int kona_reset_handler(struct notifier_block *this,
  29                                unsigned long mode, void *cmd)
  30{
  31        /*
  32         * A soft reset is triggered by writing a 0 to bit 0 of the soft reset
  33         * register. To write to that register we must first write the password
  34         * and the enable bit in the write access enable register.
  35         */
  36        writel((RSTMGR_WR_PASSWORD << RSTMGR_WR_PASSWORD_SHIFT) |
  37                RSTMGR_WR_ACCESS_ENABLE,
  38                kona_reset_base + RSTMGR_REG_WR_ACCESS_OFFSET);
  39        writel(0, kona_reset_base + RSTMGR_REG_CHIP_SOFT_RST_OFFSET);
  40
  41        return NOTIFY_DONE;
  42}
  43
  44static struct notifier_block kona_reset_nb = {
  45        .notifier_call = kona_reset_handler,
  46        .priority = 128,
  47};
  48
  49static int kona_reset_probe(struct platform_device *pdev)
  50{
  51        struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  52
  53        kona_reset_base = devm_ioremap_resource(&pdev->dev, res);
  54        if (IS_ERR(kona_reset_base))
  55                return PTR_ERR(kona_reset_base);
  56
  57        return register_restart_handler(&kona_reset_nb);
  58}
  59
  60static const struct of_device_id of_match[] = {
  61        { .compatible = "brcm,bcm21664-resetmgr" },
  62        {},
  63};
  64
  65static struct platform_driver bcm_kona_reset_driver = {
  66        .probe = kona_reset_probe,
  67        .driver = {
  68                .name = "brcm-kona-reset",
  69                .of_match_table = of_match,
  70        },
  71};
  72
  73builtin_platform_driver(bcm_kona_reset_driver);
  74