Linux Kernel  3.7.1
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leon_pmc.c
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1 /* leon_pmc.c: LEON Power-down cpu_idle() handler
2  *
3  * Copyright (C) 2011 Daniel Hellstrom ([email protected]) Aeroflex Gaisler AB
4  */
5 
6 #include <linux/init.h>
7 #include <linux/pm.h>
8 
9 #include <asm/leon_amba.h>
10 #include <asm/cpu_type.h>
11 #include <asm/leon.h>
12 
13 /* List of Systems that need fixup instructions around power-down instruction */
14 unsigned int pmc_leon_fixup_ids[] = {
18  0
19 };
20 
22 {
23  unsigned int systemid = amba_system_id >> 16;
24  unsigned int *id;
25 
26  id = &pmc_leon_fixup_ids[0];
27  while (*id != 0) {
28  if (*id == systemid)
29  return 1;
30  id++;
31  }
32 
33  return 0;
34 }
35 
36 /*
37  * CPU idle callback function for systems that need some extra handling
38  * See .../arch/sparc/kernel/process.c
39  */
41 {
42  /* Prepare an address to a non-cachable region. APB is always
43  * none-cachable. One instruction is executed after the Sleep
44  * instruction, we make sure to read the bus and throw away the
45  * value by accessing a non-cachable area, also we make sure the
46  * MMU does not get a TLB miss here by using the MMU BYPASS ASI.
47  */
48  register unsigned int address = (unsigned int)leon3_irqctrl_regs;
49  __asm__ __volatile__ (
50  "mov %%g0, %%asr19\n"
51  "lda [%0] %1, %%g0\n"
52  :
53  : "r"(address), "i"(ASI_LEON_BYPASS));
54 }
55 
56 /*
57  * CPU idle callback function
58  * See .../arch/sparc/kernel/process.c
59  */
60 void pmc_leon_idle(void)
61 {
62  /* For systems without power-down, this will be no-op */
63  __asm__ __volatile__ ("mov %g0, %asr19\n\t");
64 }
65 
66 /* Install LEON Power Down function */
67 static int __init leon_pmc_install(void)
68 {
69  if (sparc_cpu_model == sparc_leon) {
70  /* Assign power management IDLE handler */
71  if (pmc_leon_need_fixup())
73  else
75 
76  printk(KERN_INFO "leon: power management initialized\n");
77  }
78 
79  return 0;
80 }
81 
82 /* This driver is not critical to the boot process, don't care
83  * if initialized late.
84  */
85 late_initcall(leon_pmc_install);