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
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