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/bcm2835.h>
  18 #include <linux/of_address.h>
  19 #include <linux/of_platform.h>
  20 #include <linux/clk/bcm2835.h>
  21 #include <linux/clocksource.h>
  22
  23 #include <asm/mach/arch.h>
  24 #include <asm/mach/map.h>
  25
  26 #define PM_RSTC                         0x1c
  27 #define PM_RSTS                         0x20
  28 #define PM_WDOG                         0x24
  29
  30 #define PM_PASSWORD                     0x5a000000
  31 #define PM_RSTC_WRCFG_MASK              0x00000030
  32 #define PM_RSTC_WRCFG_FULL_RESET        0x00000020
  33 #define PM_RSTS_HADWRH_SET              0x00000040
  34
  35 #define BCM2835_PERIPH_PHYS     0x20000000
  36 #define BCM2835_PERIPH_VIRT     0xf0000000
  37 #define BCM2835_PERIPH_SIZE     SZ_16M
  38
  39 static void __iomem *wdt_regs;
  40
  41 /*
  42  * The machine restart method can be called from an atomic context so we won't
  43  * be able to ioremap the regs then.
  44  */
  45 static void bcm2835_setup_restart(void)
  46 {
  47         struct device_node *np = of_find_compatible_node(NULL, NULL,
  48                                                 "brcm,bcm2835-pm-wdt");
  49         if (WARN(!np, "unable to setup watchdog restart"))
  50                 return;
  51
  52         wdt_regs = of_iomap(np, 0);
  53         WARN(!wdt_regs, "failed to remap watchdog regs");
  54 }
  55
  56 static void bcm2835_restart(enum reboot_mode mode, const char *cmd)
  57 {
  58         u32 val;
  59
  60         if (!wdt_regs)
  61                 return;
  62
  63         /* use a timeout of 10 ticks (~150us) */
  64         writel_relaxed(10 | PM_PASSWORD, wdt_regs + PM_WDOG);
  65         val = readl_relaxed(wdt_regs + PM_RSTC);
  66         val &= ~PM_RSTC_WRCFG_MASK;
  67         val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
  68         writel_relaxed(val, wdt_regs + PM_RSTC);
  69
  70         /* No sleeping, possibly atomic. */
  71         mdelay(1);
  72 }
  73
  74 /*
  75  * We can't really power off, but if we do the normal reset scheme, and
  76  * indicate to bootcode.bin not to reboot, then most of the chip will be
  77  * powered off.
  78  */
  79 static void bcm2835_power_off(void)
  80 {
  81         u32 val;
  82
  83         /*
  84          * We set the watchdog hard reset bit here to distinguish this reset
  85          * from the normal (full) reset. bootcode.bin will not reboot after a
  86          * hard reset.
  87          */
  88         val = readl_relaxed(wdt_regs + PM_RSTS);
  89         val &= ~PM_RSTC_WRCFG_MASK;
  90         val |= PM_PASSWORD | PM_RSTS_HADWRH_SET;
  91         writel_relaxed(val, wdt_regs + PM_RSTS);
  92
  93         /* Continue with normal reset mechanism */
  94         bcm2835_restart(REBOOT_HARD, "");
  95 }
  96
  97 static struct map_desc io_map __initdata = {
  98         .virtual = BCM2835_PERIPH_VIRT,
  99         .pfn = __phys_to_pfn(BCM2835_PERIPH_PHYS),
 100         .length = BCM2835_PERIPH_SIZE,
 101         .type = MT_DEVICE
 102 };
 103
 104 static void __init bcm2835_map_io(void)
 105 {
 106         iotable_init(&io_map, 1);
 107 }
 108
 109 static void __init bcm2835_init(void)
 110 {
 111         int ret;
 112
 113         bcm2835_setup_restart();
 114         if (wdt_regs)
 115                 pm_power_off = bcm2835_power_off;
 116
 117         bcm2835_init_clocks();
 118
 119         ret = of_platform_populate(NULL, of_default_bus_match_table, NULL,
 120                                    NULL);
 121         if (ret) {
 122                 pr_err("of_platform_populate failed: %d\n", ret);
 123                 BUG();
 124         }
 125 }
 126
 127 static const char * const bcm2835_compat[] = {
 128         "brcm,bcm2835",
 129         NULL
 130 };
 131
 132 DT_MACHINE_START(BCM2835, "BCM2835")
 133         .map_io = bcm2835_map_io,
 134         .init_irq = bcm2835_init_irq,
 135         .handle_irq = bcm2835_handle_irq,
 136         .init_machine = bcm2835_init,
 137         .init_time = clocksource_of_init,
 138         .restart = bcm2835_restart,
 139         .dt_compat = bcm2835_compat
 140 MACHINE_END