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 */
picoxcell_setup_restart(void)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
picoxcell_map_io(void)46 static void __init picoxcell_map_io(void)
47 {
48 iotable_init(&io_map, 1);
49 }
50
picoxcell_init_machine(void)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
picoxcell_wdt_restart(enum reboot_mode mode,const char * cmd)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
82