1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/kernel.h>
3 #include <linux/module.h>
4 #include <linux/delay.h>
5 #include <linux/gpio.h>
6 #include <linux/io.h>
7 #include <asm/proc-fns.h>
8 #include <asm/system_misc.h>
9
10 #include "regs-ost.h"
11 #include "reset.h"
12 #include "smemc.h"
13 #include "generic.h"
14
15 static void do_hw_reset(void);
16
17 static int reset_gpio = -1;
18
19 int init_gpio_reset(int gpio, int output, int level)
20 {
21 int rc;
22
23 rc = gpio_request(gpio, "reset generator");
24 if (rc) {
25 printk(KERN_ERR "Can't request reset_gpio\n");
26 goto out;
27 }
28
29 if (output)
30 rc = gpio_direction_output(gpio, level);
31 else
32 rc = gpio_direction_input(gpio);
33 if (rc) {
34 printk(KERN_ERR "Can't configure reset_gpio\n");
35 gpio_free(gpio);
36 goto out;
37 }
38
39 out:
40 if (!rc)
41 reset_gpio = gpio;
42
43 return rc;
44 }
45
46 /*
47 * Trigger GPIO reset.
48 * This covers various types of logic connecting gpio pin
49 * to RESET pins (nRESET or GPIO_RESET):
50 */
51 static void do_gpio_reset(void)
52 {
53 BUG_ON(reset_gpio == -1);
54
55 /* drive it low */
56 gpio_direction_output(reset_gpio, 0);
57 mdelay(2);
58 /* rising edge or drive high */
59 gpio_set_value(reset_gpio, 1);
60 mdelay(2);
61 /* falling edge */
62 gpio_set_value(reset_gpio, 0);
63
64 /* give it some time */
65 mdelay(10);
66
67 WARN_ON(1);
68 /* fallback */
69 do_hw_reset();
70 }
71
72 static void do_hw_reset(void)
73 {
74 /* Initialize the watchdog and let it fire */
75 writel_relaxed(OWER_WME, OWER);
76 writel_relaxed(OSSR_M3, OSSR);
77 /* ... in 100 ms */
78 writel_relaxed(readl_relaxed(OSCR) + 368640, OSMR3);
79 /*
80 * SDRAM hangs on watchdog reset on Marvell PXA270 (erratum 71)
81 * we put SDRAM into self-refresh to prevent that
82 */
83 while (1)
84 writel_relaxed(MDREFR_SLFRSH, MDREFR);
85 }
86
87 void pxa_restart(enum reboot_mode mode, const char *cmd)
88 {
89 local_irq_disable();
90 local_fiq_disable();
91
92 clear_reset_status(RESET_STATUS_ALL);
93
94 switch (mode) {
95 case REBOOT_SOFT:
96 /* Jump into ROM at address 0 */
97 soft_restart(0);
98 break;
99 case REBOOT_GPIO:
100 do_gpio_reset();
101 break;
102 case REBOOT_HARD:
103 default:
104 do_hw_reset();
105 break;
106 }
107 }
108
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