arch/arm/mach-bcm2835/bcm2835.c

   1 /*
   2  * Copyright (C) 2010 Broadcom
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #include <linux/delay.h>
  16 #include <linux/init.h>
  17 #include <linux/irqchip.h>
  18 #include <linux/of_address.h>
  19 #include <linux/of_platform.h>
  20 #include <linux/clk/bcm2835.h>
  21
  22 #include <asm/mach/arch.h>
  23 #include <asm/mach/map.h>
  24
  25 #define PM_RSTC                         0x1c
  26 #define PM_RSTS                         0x20
  27 #define PM_WDOG                         0x24
  28
  29 #define PM_PASSWORD                     0x5a000000
  30 #define PM_RSTC_WRCFG_MASK              0x00000030
  31 #define PM_RSTC_WRCFG_FULL_RESET        0x00000020
  32 #define PM_RSTS_HADWRH_SET              0x00000040
  33
  34 #define BCM2835_PERIPH_PHYS     0x20000000
  35 #define BCM2835_PERIPH_VIRT     0xf0000000
  36 #define BCM2835_PERIPH_SIZE     SZ_16M
  37
  38 static void __iomem *wdt_regs;
  39
  40 /*
  41  * The machine restart method can be called from an atomic context so we won't
  42  * be able to ioremap the regs then.
  43  */
  44 static void bcm2835_setup_restart(void)
  45 {
  46         struct device_node *np = of_find_compatible_node(NULL, NULL,
  47                                                 "brcm,bcm2835-pm-wdt");
  48         if (WARN(!np, "unable to setup watchdog restart"))
  49                 return;
  50
  51         wdt_regs = of_iomap(np, 0);
  52         WARN(!wdt_regs, "failed to remap watchdog regs");
  53 }
  54
  55 static void bcm2835_restart(enum reboot_mode mode, const char *cmd)
  56 {
  57         u32 val;
  58
  59         if (!wdt_regs)
  60                 return;
  61
  62         /* use a timeout of 10 ticks (~150us) */
  63         writel_relaxed(10 | PM_PASSWORD, wdt_regs + PM_WDOG);
  64         val = readl_relaxed(wdt_regs + PM_RSTC);
  65         val &= ~PM_RSTC_WRCFG_MASK;
  66         val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
  67         writel_relaxed(val, wdt_regs + PM_RSTC);
  68
  69         /* No sleeping, possibly atomic. */
  70         mdelay(1);
  71 }
  72
  73 /*
  74  * We can't really power off, but if we do the normal reset scheme, and
  75  * indicate to bootcode.bin not to reboot, then most of the chip will be
  76  * powered off.
  77  */
  78 static void bcm2835_power_off(void)
  79 {
  80         u32 val;
  81
  82         /*
  83          * We set the watchdog hard reset bit here to distinguish this reset
  84          * from the normal (full) reset. bootcode.bin will not reboot after a
  85          * hard reset.
  86          */
  87         val = readl_relaxed(wdt_regs + PM_RSTS);
  88         val &= ~PM_RSTC_WRCFG_MASK;
  89         val |= PM_PASSWORD | PM_RSTS_HADWRH_SET;
  90         writel_relaxed(val, wdt_regs + PM_RSTS);
  91
  92         /* Continue with normal reset mechanism */
  93         bcm2835_restart(REBOOT_HARD, "");
  94 }
  95
  96 static struct map_desc io_map __initdata = {
  97         .virtual = BCM2835_PERIPH_VIRT,
  98         .pfn = __phys_to_pfn(BCM2835_PERIPH_PHYS),
  99         .length = BCM2835_PERIPH_SIZE,
 100         .type = MT_DEVICE
 101 };
 102
 103 static void __init bcm2835_map_io(void)
 104 {
 105         iotable_init(&io_map, 1);
 106 }
 107
 108 static void __init bcm2835_init(void)
 109 {
 110         int ret;
 111
 112         bcm2835_setup_restart();
 113         if (wdt_regs)
 114                 pm_power_off = bcm2835_power_off;
 115
 116         bcm2835_init_clocks();
 117
 118         ret = of_platform_populate(NULL, of_default_bus_match_table, NULL,
 119                                    NULL);
 120         if (ret) {
 121                 pr_err("of_platform_populate failed: %d\n", ret);
 122                 BUG();
 123         }
 124 }
 125
 126 static const char * const bcm2835_compat[] = {
 127         "brcm,bcm2835",
 128         NULL
 129 };
 130
 131 DT_MACHINE_START(BCM2835, "BCM2835")
 132         .map_io = bcm2835_map_io,
 133         .init_irq = irqchip_init,
 134         .init_machine = bcm2835_init,
 135         .restart = bcm2835_restart,
 136         .dt_compat = bcm2835_compat
 137 MACHINE_END