1 // SPDX-License-Identifier: GPL-2.0
2 /* leon_pmc.c: LEON Power-down cpu_idle() handler
4 * Copyright (C) 2011 Daniel Hellstrom (daniel@gaisler.com) Aeroflex Gaisler AB
7 #include <linux/init.h>
10 #include <asm/leon_amba.h>
11 #include <asm/cpu_type.h>
13 #include <asm/processor.h>
15 /* List of Systems that need fixup instructions around power-down instruction */
16 static unsigned int pmc_leon_fixup_ids
[] = {
23 static int pmc_leon_need_fixup(void)
25 unsigned int systemid
= amba_system_id
>> 16;
28 id
= &pmc_leon_fixup_ids
[0];
39 * CPU idle callback function for systems that need some extra handling
40 * See .../arch/sparc/kernel/process.c
42 static void pmc_leon_idle_fixup(void)
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.
50 register unsigned int address
= (unsigned int)leon3_irqctrl_regs
;
52 /* Interrupts need to be enabled to not hang the CPU */
53 raw_local_irq_enable();
55 __asm__
__volatile__ (
59 : "r"(address
), "i"(ASI_LEON_BYPASS
));
61 raw_local_irq_disable();
65 * CPU idle callback function
66 * See .../arch/sparc/kernel/process.c
68 static void pmc_leon_idle(void)
70 /* Interrupts need to be enabled to not hang the CPU */
71 raw_local_irq_enable();
73 /* For systems without power-down, this will be no-op */
74 __asm__
__volatile__ ("wr %g0, %asr19\n\t");
76 raw_local_irq_disable();
79 /* Install LEON Power Down function */
80 static int __init
leon_pmc_install(void)
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
;
87 sparc_idle
= pmc_leon_idle
;
89 printk(KERN_INFO
"leon: power management initialized\n");
95 /* This driver is not critical to the boot process, don't care
96 * if initialized late.
98 late_initcall(leon_pmc_install
);