1 /* leon_pmc.c: LEON Power-down cpu_idle() handler
2 *
3 * Copyright (C) 2011 Daniel Hellstrom (daniel@gaisler.com) 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 #include <asm/processor.h>
13
14 /* List of Systems that need fixup instructions around power-down instruction */
15 static unsigned int pmc_leon_fixup_ids[] = {
16 AEROFLEX_UT699,
17 GAISLER_GR712RC,
18 LEON4_NEXTREME1,
19 0
20 };
21
pmc_leon_need_fixup(void)22 static int pmc_leon_need_fixup(void)
23 {
24 unsigned int systemid = amba_system_id >> 16;
25 unsigned int *id;
26
27 id = &pmc_leon_fixup_ids[0];
28 while (*id != 0) {
29 if (*id == systemid)
30 return 1;
31 id++;
32 }
33
34 return 0;
35 }
36
37 /*
38 * CPU idle callback function for systems that need some extra handling
39 * See .../arch/sparc/kernel/process.c
40 */
pmc_leon_idle_fixup(void)41 static void pmc_leon_idle_fixup(void)
42 {
43 /* Prepare an address to a non-cachable region. APB is always
44 * none-cachable. One instruction is executed after the Sleep
45 * instruction, we make sure to read the bus and throw away the
46 * value by accessing a non-cachable area, also we make sure the
47 * MMU does not get a TLB miss here by using the MMU BYPASS ASI.
48 */
49 register unsigned int address = (unsigned int)leon3_irqctrl_regs;
50
51 /* Interrupts need to be enabled to not hang the CPU */
52 local_irq_enable();
53
54 __asm__ __volatile__ (
55 "wr %%g0, %%asr19\n"
56 "lda [%0] %1, %%g0\n"
57 :
58 : "r"(address), "i"(ASI_LEON_BYPASS));
59 }
60
61 /*
62 * CPU idle callback function
63 * See .../arch/sparc/kernel/process.c
64 */
pmc_leon_idle(void)65 static void pmc_leon_idle(void)
66 {
67 /* Interrupts need to be enabled to not hang the CPU */
68 local_irq_enable();
69
70 /* For systems without power-down, this will be no-op */
71 __asm__ __volatile__ ("wr %g0, %asr19\n\t");
72 }
73
74 /* Install LEON Power Down function */
leon_pmc_install(void)75 static int __init leon_pmc_install(void)
76 {
77 if (sparc_cpu_model == sparc_leon) {
78 /* Assign power management IDLE handler */
79 if (pmc_leon_need_fixup())
80 sparc_idle = pmc_leon_idle_fixup;
81 else
82 sparc_idle = pmc_leon_idle;
83
84 printk(KERN_INFO "leon: power management initialized\n");
85 }
86
87 return 0;
88 }
89
90 /* This driver is not critical to the boot process, don't care
91 * if initialized late.
92 */
93 late_initcall(leon_pmc_install);
94