xref: /linux/arch/sparc/kernel/leon_pmc.c (revision 827634added7f38b7d724cab1dccdb2b004c13c3)
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 
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  */
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  */
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 */
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