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
  26 static void __iomem *kona_reset_base;
  27
  28 static 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
  44 static struct notifier_block kona_reset_nb = {
  45         .notifier_call = kona_reset_handler,
  46         .priority = 128,
  47 };
  48
  49 static 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
  60 static const struct of_device_id of_match[] = {
  61         { .compatible = "brcm,bcm21664-resetmgr" },
  62         {},
  63 };
  64
  65 static 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
  73 builtin_platform_driver(bcm_kona_reset_driver);