1 /*
2 * Copyright (c) 2011 Picochip Ltd., Jamie Iles
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 version 2 as
6 * published by the Free Software Foundation.
7 *
8 * All enquiries to support@picochip.com
9 */
10 #include <linux/delay.h>
11 #include <linux/of.h>
12 #include <linux/of_address.h>
13 #include <linux/of_platform.h>
14 #include <linux/reboot.h>
15
16 #include <asm/mach/arch.h>
17 #include <asm/mach/map.h>
18
19 #define PHYS_TO_IO(x) (((x) & 0x00ffffff) | 0xfe000000)
20 #define PICOXCELL_PERIPH_BASE 0x80000000
21 #define PICOXCELL_PERIPH_LENGTH SZ_4M
22
23 #define WDT_CTRL_REG_EN_MASK (1 << 0)
24 #define WDT_CTRL_REG_OFFS (0x00)
25 #define WDT_TIMEOUT_REG_OFFS (0x04)
26 static void __iomem *wdt_regs;
27
28 /*
29 * The machine restart method can be called from an atomic context so we won't
30 * be able to ioremap the regs then.
31 */
picoxcell_setup_restart(void)32 static void picoxcell_setup_restart(void)
33 {
34 struct device_node *np = of_find_compatible_node(NULL, NULL,
35 "snps,dw-apb-wdg");
36 if (WARN(!np, "unable to setup watchdog restart"))
37 return;
38
39 wdt_regs = of_iomap(np, 0);
40 WARN(!wdt_regs, "failed to remap watchdog regs");
41 }
42
43 static struct map_desc io_map __initdata = {
44 .virtual = PHYS_TO_IO(PICOXCELL_PERIPH_BASE),
45 .pfn = __phys_to_pfn(PICOXCELL_PERIPH_BASE),
46 .length = PICOXCELL_PERIPH_LENGTH,
47 .type = MT_DEVICE,
48 };
49
picoxcell_map_io(void)50 static void __init picoxcell_map_io(void)
51 {
52 iotable_init(&io_map, 1);
53 }
54
picoxcell_init_machine(void)55 static void __init picoxcell_init_machine(void)
56 {
57 of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
58 picoxcell_setup_restart();
59 }
60
61 static const char *picoxcell_dt_match[] = {
62 "picochip,pc3x2",
63 "picochip,pc3x3",
64 NULL
65 };
66
picoxcell_wdt_restart(enum reboot_mode mode,const char * cmd)67 static void picoxcell_wdt_restart(enum reboot_mode mode, const char *cmd)
68 {
69 /*
70 * Configure the watchdog to reset with the shortest possible timeout
71 * and give it chance to do the reset.
72 */
73 if (wdt_regs) {
74 writel_relaxed(WDT_CTRL_REG_EN_MASK, wdt_regs + WDT_CTRL_REG_OFFS);
75 writel_relaxed(0, wdt_regs + WDT_TIMEOUT_REG_OFFS);
76 /* No sleeping, possibly atomic. */
77 mdelay(500);
78 }
79 }
80
81 DT_MACHINE_START(PICOXCELL, "Picochip picoXcell")
82 .map_io = picoxcell_map_io,
83 .init_machine = picoxcell_init_machine,
84 .dt_compat = picoxcell_dt_match,
85 .restart = picoxcell_wdt_restart,
86 MACHINE_END
87