Linux Kernel  3.7.1
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reset.c
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1 /*
2  * This program is free software; you can redistribute it and/or modify
3  * it under the terms of the GNU General Public License version 2 as
4  * published by the Free Software Foundation.
5  */
6 #include <linux/kernel.h>
7 #include <linux/module.h>
8 #include <linux/delay.h>
9 #include <linux/gpio.h>
10 #include <linux/io.h>
11 #include <asm/proc-fns.h>
12 #include <asm/system_misc.h>
13 
14 #include <mach/regs-ost.h>
15 #include <mach/reset.h>
16 
17 unsigned int reset_status;
19 
20 static void do_hw_reset(void);
21 
22 static int reset_gpio = -1;
23 
24 int init_gpio_reset(int gpio, int output, int level)
25 {
26  int rc;
27 
28  rc = gpio_request(gpio, "reset generator");
29  if (rc) {
30  printk(KERN_ERR "Can't request reset_gpio\n");
31  goto out;
32  }
33 
34  if (output)
35  rc = gpio_direction_output(gpio, level);
36  else
37  rc = gpio_direction_input(gpio);
38  if (rc) {
39  printk(KERN_ERR "Can't configure reset_gpio\n");
40  gpio_free(gpio);
41  goto out;
42  }
43 
44 out:
45  if (!rc)
46  reset_gpio = gpio;
47 
48  return rc;
49 }
50 
51 /*
52  * Trigger GPIO reset.
53  * This covers various types of logic connecting gpio pin
54  * to RESET pins (nRESET or GPIO_RESET):
55  */
56 static void do_gpio_reset(void)
57 {
58  BUG_ON(reset_gpio == -1);
59 
60  /* drive it low */
61  gpio_direction_output(reset_gpio, 0);
62  mdelay(2);
63  /* rising edge or drive high */
64  gpio_set_value(reset_gpio, 1);
65  mdelay(2);
66  /* falling edge */
67  gpio_set_value(reset_gpio, 0);
68 
69  /* give it some time */
70  mdelay(10);
71 
72  WARN_ON(1);
73  /* fallback */
74  do_hw_reset();
75 }
76 
77 static void do_hw_reset(void)
78 {
79  /* Initialize the watchdog and let it fire */
80  writel_relaxed(OWER_WME, OWER);
81  writel_relaxed(OSSR_M3, OSSR);
82  /* ... in 100 ms */
83  writel_relaxed(readl_relaxed(OSCR) + 368640, OSMR3);
84 }
85 
86 void pxa_restart(char mode, const char *cmd)
87 {
89  local_fiq_disable();
90 
92 
93  switch (mode) {
94  case 's':
95  /* Jump into ROM at address 0 */
96  soft_restart(0);
97  break;
98  case 'g':
99  do_gpio_reset();
100  break;
101  case 'h':
102  default:
103  do_hw_reset();
104  break;
105  }
106 }
107