arch/arm/mach-picoxcell/common.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2011 Picochip Ltd., Jamie Iles
   4  *
   5  * All enquiries to support@picochip.com
   6  */
   7 #include <linux/delay.h>
   8 #include <linux/of.h>
   9 #include <linux/of_address.h>
  10 #include <linux/reboot.h>
  11
  12 #include <asm/mach/arch.h>
  13 #include <asm/mach/map.h>
  14
  15 #define PHYS_TO_IO(x)                   (((x) & 0x00ffffff) | 0xfe000000)
  16 #define PICOXCELL_PERIPH_BASE           0x80000000
  17 #define PICOXCELL_PERIPH_LENGTH         SZ_4M
  18
  19 #define WDT_CTRL_REG_EN_MASK            (1 << 0)
  20 #define WDT_CTRL_REG_OFFS               (0x00)
  21 #define WDT_TIMEOUT_REG_OFFS            (0x04)
  22 static void __iomem *wdt_regs;
  23
  24 /*
  25  * The machine restart method can be called from an atomic context so we won't
  26  * be able to ioremap the regs then.
  27  */
  28 static void picoxcell_setup_restart(void)
  29 {
  30         struct device_node *np = of_find_compatible_node(NULL, NULL,
  31                                                          "snps,dw-apb-wdg");
  32         if (WARN(!np, "unable to setup watchdog restart"))
  33                 return;
  34
  35         wdt_regs = of_iomap(np, 0);
  36         WARN(!wdt_regs, "failed to remap watchdog regs");
  37 }
  38
  39 static struct map_desc io_map __initdata = {
  40         .virtual        = PHYS_TO_IO(PICOXCELL_PERIPH_BASE),
  41         .pfn            = __phys_to_pfn(PICOXCELL_PERIPH_BASE),
  42         .length         = PICOXCELL_PERIPH_LENGTH,
  43         .type           = MT_DEVICE,
  44 };
  45
  46 static void __init picoxcell_map_io(void)
  47 {
  48         iotable_init(&io_map, 1);
  49 }
  50
  51 static void __init picoxcell_init_machine(void)
  52 {
  53         picoxcell_setup_restart();
  54 }
  55
  56 static const char *picoxcell_dt_match[] = {
  57         "picochip,pc3x2",
  58         "picochip,pc3x3",
  59         NULL
  60 };
  61
  62 static void picoxcell_wdt_restart(enum reboot_mode mode, const char *cmd)
  63 {
  64         /*
  65          * Configure the watchdog to reset with the shortest possible timeout
  66          * and give it chance to do the reset.
  67          */
  68         if (wdt_regs) {
  69                 writel_relaxed(WDT_CTRL_REG_EN_MASK, wdt_regs + WDT_CTRL_REG_OFFS);
  70                 writel_relaxed(0, wdt_regs + WDT_TIMEOUT_REG_OFFS);
  71                 /* No sleeping, possibly atomic. */
  72                 mdelay(500);
  73         }
  74 }
  75
  76 DT_MACHINE_START(PICOXCELL, "Picochip picoXcell")
  77         .map_io         = picoxcell_map_io,
  78         .init_machine   = picoxcell_init_machine,
  79         .dt_compat      = picoxcell_dt_match,
  80         .restart        = picoxcell_wdt_restart,
  81 MACHINE_END