drivers/power/reset/ocelot-reset.c

   1 // SPDX-License-Identifier: (GPL-2.0 OR MIT)
   2 /*
   3  * Microsemi MIPS SoC reset driver
   4  *
   5  * License: Dual MIT/GPL
   6  * Copyright (c) 2017 Microsemi Corporation
   7  */
   8 #include <linux/delay.h>
   9 #include <linux/io.h>
  10 #include <linux/notifier.h>
  11 #include <linux/mfd/syscon.h>
  12 #include <linux/of_address.h>
  13 #include <linux/of_device.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/reboot.h>
  16 #include <linux/regmap.h>
  17
  18 struct ocelot_reset_context {
  19         void __iomem *base;
  20         struct regmap *cpu_ctrl;
  21         struct notifier_block restart_handler;
  22 };
  23
  24 #define ICPU_CFG_CPU_SYSTEM_CTRL_RESET 0x20
  25 #define CORE_RST_PROTECT BIT(2)
  26
  27 #define SOFT_CHIP_RST BIT(0)
  28
  29 static int ocelot_restart_handle(struct notifier_block *this,
  30                                  unsigned long mode, void *cmd)
  31 {
  32         struct ocelot_reset_context *ctx = container_of(this, struct
  33                                                         ocelot_reset_context,
  34                                                         restart_handler);
  35
  36         /* Make sure the core is not protected from reset */
  37         regmap_update_bits(ctx->cpu_ctrl, ICPU_CFG_CPU_SYSTEM_CTRL_RESET,
  38                            CORE_RST_PROTECT, 0);
  39
  40         writel(SOFT_CHIP_RST, ctx->base);
  41
  42         pr_emerg("Unable to restart system\n");
  43         return NOTIFY_DONE;
  44 }
  45
  46 static int ocelot_reset_probe(struct platform_device *pdev)
  47 {
  48         struct ocelot_reset_context *ctx;
  49         struct resource *res;
  50
  51         struct device *dev = &pdev->dev;
  52         int err;
  53
  54         ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
  55         if (!ctx)
  56                 return -ENOMEM;
  57
  58         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  59         ctx->base = devm_ioremap_resource(dev, res);
  60         if (IS_ERR(ctx->base))
  61                 return PTR_ERR(ctx->base);
  62
  63         ctx->cpu_ctrl = syscon_regmap_lookup_by_compatible("mscc,ocelot-cpu-syscon");
  64         if (IS_ERR(ctx->cpu_ctrl))
  65                 return PTR_ERR(ctx->cpu_ctrl);
  66
  67         ctx->restart_handler.notifier_call = ocelot_restart_handle;
  68         ctx->restart_handler.priority = 192;
  69         err = register_restart_handler(&ctx->restart_handler);
  70         if (err)
  71                 dev_err(dev, "can't register restart notifier (err=%d)\n", err);
  72
  73         return err;
  74 }
  75
  76 static const struct of_device_id ocelot_reset_of_match[] = {
  77         { .compatible = "mscc,ocelot-chip-reset" },
  78         {}
  79 };
  80
  81 static struct platform_driver ocelot_reset_driver = {
  82         .probe = ocelot_reset_probe,
  83         .driver = {
  84                 .name = "ocelot-chip-reset",
  85                 .of_match_table = ocelot_reset_of_match,
  86         },
  87 };
  88 builtin_platform_driver(ocelot_reset_driver);