1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* leon_pmc.c: LEON Power-down cpu_idle() handler |
3 | * |
4 | * Copyright (C) 2011 Daniel Hellstrom (daniel@gaisler.com) Aeroflex Gaisler AB |
5 | */ |
6 | |
7 | #include <linux/init.h> |
8 | #include <linux/pm.h> |
9 | |
10 | #include <asm/leon_amba.h> |
11 | #include <asm/cpu_type.h> |
12 | #include <asm/leon.h> |
13 | #include <asm/processor.h> |
14 | |
15 | /* List of Systems that need fixup instructions around power-down instruction */ |
16 | static unsigned int pmc_leon_fixup_ids[] = { |
17 | AEROFLEX_UT699, |
18 | GAISLER_GR712RC, |
19 | LEON4_NEXTREME1, |
20 | 0 |
21 | }; |
22 | |
23 | static int pmc_leon_need_fixup(void) |
24 | { |
25 | unsigned int systemid = amba_system_id >> 16; |
26 | unsigned int *id; |
27 | |
28 | id = &pmc_leon_fixup_ids[0]; |
29 | while (*id != 0) { |
30 | if (*id == systemid) |
31 | return 1; |
32 | id++; |
33 | } |
34 | |
35 | return 0; |
36 | } |
37 | |
38 | /* |
39 | * CPU idle callback function for systems that need some extra handling |
40 | * See .../arch/sparc/kernel/process.c |
41 | */ |
42 | static void pmc_leon_idle_fixup(void) |
43 | { |
44 | /* Prepare an address to a non-cachable region. APB is always |
45 | * none-cachable. One instruction is executed after the Sleep |
46 | * instruction, we make sure to read the bus and throw away the |
47 | * value by accessing a non-cachable area, also we make sure the |
48 | * MMU does not get a TLB miss here by using the MMU BYPASS ASI. |
49 | */ |
50 | register unsigned int address = (unsigned int)leon3_irqctrl_regs; |
51 | |
52 | /* Interrupts need to be enabled to not hang the CPU */ |
53 | raw_local_irq_enable(); |
54 | |
55 | __asm__ __volatile__ ( |
56 | "wr %%g0, %%asr19\n" |
57 | "lda [%0] %1, %%g0\n" |
58 | : |
59 | : "r" (address), "i" (ASI_LEON_BYPASS)); |
60 | |
61 | raw_local_irq_disable(); |
62 | } |
63 | |
64 | /* |
65 | * CPU idle callback function |
66 | * See .../arch/sparc/kernel/process.c |
67 | */ |
68 | static void pmc_leon_idle(void) |
69 | { |
70 | /* Interrupts need to be enabled to not hang the CPU */ |
71 | raw_local_irq_enable(); |
72 | |
73 | /* For systems without power-down, this will be no-op */ |
74 | __asm__ __volatile__ ("wr %g0, %asr19\n\t" ); |
75 | |
76 | raw_local_irq_disable(); |
77 | } |
78 | |
79 | /* Install LEON Power Down function */ |
80 | static int __init leon_pmc_install(void) |
81 | { |
82 | if (sparc_cpu_model == sparc_leon) { |
83 | /* Assign power management IDLE handler */ |
84 | if (pmc_leon_need_fixup()) |
85 | sparc_idle = pmc_leon_idle_fixup; |
86 | else |
87 | sparc_idle = pmc_leon_idle; |
88 | |
89 | printk(KERN_INFO "leon: power management initialized\n" ); |
90 | } |
91 | |
92 | return 0; |
93 | } |
94 | |
95 | /* This driver is not critical to the boot process, don't care |
96 | * if initialized late. |
97 | */ |
98 | late_initcall(leon_pmc_install); |
99 | |