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
138