[linux.git] / arch / mips / kernel / idle.c

/*
 * MIPS idle loop and WAIT instruction support.
 *
 * Copyright (C) xxxx  the Anonymous
 * Copyright (C) 1994 - 2006 Ralf Baechle
 * Copyright (C) 2003, 2004  Maciej W. Rozycki
 * Copyright (C) 2001, 2004, 2011, 2012	 MIPS Technologies, Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */
#include <linux/export.h>
#include <linux/init.h>
#include <linux/irqflags.h>
#include <linux/printk.h>
#include <linux/sched.h>
#include <asm/cpu.h>
#include <asm/cpu-info.h>
#include <asm/mipsregs.h>

/*
 * Not all of the MIPS CPUs have the "wait" instruction available. Moreover,
 * the implementation of the "wait" feature differs between CPU families. This
 * points to the function that implements CPU specific wait.
 * The wait instruction stops the pipeline and reduces the power consumption of
 * the CPU very much.
 */
void (*cpu_wait)(void);
EXPORT_SYMBOL(cpu_wait);

static void r3081_wait(void)
{
	unsigned long cfg = read_c0_conf();
	write_c0_conf(cfg | R30XX_CONF_HALT);
	local_irq_enable();
}

static void r39xx_wait(void)
{
	if (!need_resched())
		write_c0_conf(read_c0_conf() | TX39_CONF_HALT);
	local_irq_enable();
}

extern void r4k_wait(void);

/*
 * This variant is preferable as it allows testing need_resched and going to
 * sleep depending on the outcome atomically.  Unfortunately the "It is
 * implementation-dependent whether the pipeline restarts when a non-enabled
 * interrupt is requested" restriction in the MIPS32/MIPS64 architecture makes
 * using this version a gamble.
 */
void r4k_wait_irqoff(void)
{
	if (!need_resched())
		__asm__(
		"	.set	push		\n"
		"	.set	mips3		\n"
		"	wait			\n"
		"	.set	pop		\n");
	local_irq_enable();
	__asm__(
	"	.globl __pastwait	\n"
	"__pastwait:			\n");
}

/*
 * The RM7000 variant has to handle erratum 38.	 The workaround is to not
 * have any pending stores when the WAIT instruction is executed.
 */
static void rm7k_wait_irqoff(void)
{
	if (!need_resched())
		__asm__(
		"	.set	push					\n"
		"	.set	mips3					\n"
		"	.set	noat					\n"
		"	mfc0	$1, $12					\n"
		"	sync						\n"
		"	mtc0	$1, $12		# stalls until W stage	\n"
		"	wait						\n"
		"	mtc0	$1, $12		# stalls until W stage	\n"
		"	.set	pop					\n");
	local_irq_enable();
}

/*
 * The Au1xxx wait is available only if using 32khz counter or
 * external timer source, but specifically not CP0 Counter.
 * alchemy/common/time.c may override cpu_wait!
 */
static void au1k_wait(void)
{
	__asm__(
	"	.set	mips3			\n"
	"	cache	0x14, 0(%0)		\n"
	"	cache	0x14, 32(%0)		\n"
	"	sync				\n"
	"	nop				\n"
	"	wait				\n"
	"	nop				\n"
	"	nop				\n"
	"	nop				\n"
	"	nop				\n"
	"	.set	mips0			\n"
	: : "r" (au1k_wait));
	local_irq_enable();
}

static int __initdata nowait;

static int __init wait_disable(char *s)
{
	nowait = 1;

	return 1;
}

__setup("nowait", wait_disable);

void __init check_wait(void)
{
	struct cpuinfo_mips *c = &current_cpu_data;

	if (nowait) {
		printk("Wait instruction disabled.\n");
		return;
	}

	switch (c->cputype) {
	case CPU_R3081:
	case CPU_R3081E:
		cpu_wait = r3081_wait;
		break;
	case CPU_TX3927:
		cpu_wait = r39xx_wait;
		break;
	case CPU_R4200:
/*	case CPU_R4300: */
	case CPU_R4600:
	case CPU_R4640:
	case CPU_R4650:
	case CPU_R4700:
	case CPU_R5000:
	case CPU_R5500:
	case CPU_NEVADA:
	case CPU_4KC:
	case CPU_4KEC:
	case CPU_4KSC:
	case CPU_5KC:
	case CPU_25KF:
	case CPU_PR4450:
	case CPU_BMIPS3300:
	case CPU_BMIPS4350:
	case CPU_BMIPS4380:
	case CPU_BMIPS5000:
	case CPU_CAVIUM_OCTEON:
	case CPU_CAVIUM_OCTEON_PLUS:
	case CPU_CAVIUM_OCTEON2:
	case CPU_JZRISC:
	case CPU_LOONGSON1:
	case CPU_XLR:
	case CPU_XLP:
		cpu_wait = r4k_wait;
		break;

	case CPU_RM7000:
		cpu_wait = rm7k_wait_irqoff;
		break;

	case CPU_M14KC:
	case CPU_M14KEC:
	case CPU_24K:
	case CPU_34K:
	case CPU_1004K:
		cpu_wait = r4k_wait;
		if (read_c0_config7() & MIPS_CONF7_WII)
			cpu_wait = r4k_wait_irqoff;
		break;

	case CPU_74K:
		cpu_wait = r4k_wait;
		if ((c->processor_id & 0xff) >= PRID_REV_ENCODE_332(2, 1, 0))
			cpu_wait = r4k_wait_irqoff;
		break;

	case CPU_TX49XX:
		cpu_wait = r4k_wait_irqoff;
		break;
	case CPU_ALCHEMY:
		cpu_wait = au1k_wait;
		break;
	case CPU_20KC:
		/*
		 * WAIT on Rev1.0 has E1, E2, E3 and E16.
		 * WAIT on Rev2.0 and Rev3.0 has E16.
		 * Rev3.1 WAIT is nop, why bother
		 */
		if ((c->processor_id & 0xff) <= 0x64)
			break;

		/*
		 * Another rev is incremeting c0_count at a reduced clock
		 * rate while in WAIT mode.  So we basically have the choice
		 * between using the cp0 timer as clocksource or avoiding
		 * the WAIT instruction.  Until more details are known,
		 * disable the use of WAIT for 20Kc entirely.
		   cpu_wait = r4k_wait;
		 */
		break;
	case CPU_RM9000:
		if ((c->processor_id & 0x00ff) >= 0x40)
			cpu_wait = r4k_wait;
		break;
	default:
		break;
	}
}

static void smtc_idle_hook(void)
{
#ifdef CONFIG_MIPS_MT_SMTC
	void smtc_idle_loop_hook(void);

	smtc_idle_loop_hook();
#endif
}

void arch_cpu_idle(void)
{
	smtc_idle_hook();
	if (cpu_wait)
		cpu_wait();
	else
		local_irq_enable();
}
Commit	Line	Data
49f2ec91 RB	1	/*
	2	* MIPS idle loop and WAIT instruction support.
	3	*
	4	* Copyright (C) xxxx the Anonymous
	5	* Copyright (C) 1994 - 2006 Ralf Baechle
	6	* Copyright (C) 2003, 2004 Maciej W. Rozycki
	7	* Copyright (C) 2001, 2004, 2011, 2012 MIPS Technologies, Inc.
	8	*
	9	* This program is free software; you can redistribute it and/or
	10	* modify it under the terms of the GNU General Public License
	11	* as published by the Free Software Foundation; either version
	12	* 2 of the License, or (at your option) any later version.
	13	*/
	14	#include <linux/export.h>
	15	#include <linux/init.h>
	16	#include <linux/irqflags.h>
	17	#include <linux/printk.h>
	18	#include <linux/sched.h>
	19	#include <asm/cpu.h>
	20	#include <asm/cpu-info.h>
	21	#include <asm/mipsregs.h>
	22
	23	/*
	24	* Not all of the MIPS CPUs have the "wait" instruction available. Moreover,
	25	* the implementation of the "wait" feature differs between CPU families. This
	26	* points to the function that implements CPU specific wait.
	27	* The wait instruction stops the pipeline and reduces the power consumption of
	28	* the CPU very much.
	29	*/
	30	void (*cpu_wait)(void);
	31	EXPORT_SYMBOL(cpu_wait);
	32
	33	static void r3081_wait(void)
	34	{
	35	unsigned long cfg = read_c0_conf();
	36	write_c0_conf(cfg \| R30XX_CONF_HALT);
fb40bc3e	37	local_irq_enable();
49f2ec91 RB	38	}
	39
	40	static void r39xx_wait(void)
	41	{
49f2ec91 RB	42	if (!need_resched())
	43	write_c0_conf(read_c0_conf() \| TX39_CONF_HALT);
	44	local_irq_enable();
	45	}
	46
	47	extern void r4k_wait(void);
	48
	49	/*
	50	* This variant is preferable as it allows testing need_resched and going to
	51	* sleep depending on the outcome atomically. Unfortunately the "It is
	52	* implementation-dependent whether the pipeline restarts when a non-enabled
	53	* interrupt is requested" restriction in the MIPS32/MIPS64 architecture makes
	54	* using this version a gamble.
	55	*/
	56	void r4k_wait_irqoff(void)
	57	{
49f2ec91	58	if (!need_resched())
f91a148a RB	59	__asm__(
	60	" .set push \n"
	61	" .set mips3 \n"
	62	" wait \n"
	63	" .set pop \n");
49f2ec91	64	local_irq_enable();
f91a148a RB	65	__asm__(
	66	" .globl __pastwait \n"
	67	"__pastwait: \n");
49f2ec91 RB	68	}
	69
	70	/*
	71	* The RM7000 variant has to handle erratum 38. The workaround is to not
	72	* have any pending stores when the WAIT instruction is executed.
	73	*/
	74	static void rm7k_wait_irqoff(void)
	75	{
49f2ec91 RB	76	if (!need_resched())
	77	__asm__(
	78	" .set push \n"
	79	" .set mips3 \n"
	80	" .set noat \n"
	81	" mfc0 $1, $12 \n"
	82	" sync \n"
	83	" mtc0 $1, $12 # stalls until W stage \n"
	84	" wait \n"
	85	" mtc0 $1, $12 # stalls until W stage \n"
	86	" .set pop \n");
	87	local_irq_enable();
	88	}
	89
	90	/*
	91	* The Au1xxx wait is available only if using 32khz counter or
	92	* external timer source, but specifically not CP0 Counter.
	93	* alchemy/common/time.c may override cpu_wait!
	94	*/
	95	static void au1k_wait(void)
	96	{
f91a148a RB	97	__asm__(
	98	" .set mips3 \n"
	99	" cache 0x14, 0(%0) \n"
	100	" cache 0x14, 32(%0) \n"
	101	" sync \n"
	102	" nop \n"
	103	" wait \n"
	104	" nop \n"
	105	" nop \n"
	106	" nop \n"
	107	" nop \n"
	108	" .set mips0 \n"
	109	: : "r" (au1k_wait));
fb40bc3e	110	local_irq_enable();
49f2ec91 RB	111	}
	112
	113	static int __initdata nowait;
	114
	115	static int __init wait_disable(char *s)
	116	{
	117	nowait = 1;
	118
	119	return 1;
	120	}
	121
	122	__setup("nowait", wait_disable);
	123
	124	void __init check_wait(void)
	125	{
	126	struct cpuinfo_mips *c = &current_cpu_data;
	127
	128	if (nowait) {
	129	printk("Wait instruction disabled.\n");
	130	return;
	131	}
	132
	133	switch (c->cputype) {
	134	case CPU_R3081:
	135	case CPU_R3081E:
	136	cpu_wait = r3081_wait;
	137	break;
	138	case CPU_TX3927:
	139	cpu_wait = r39xx_wait;
	140	break;
	141	case CPU_R4200:
	142	/* case CPU_R4300: */
	143	case CPU_R4600:
	144	case CPU_R4640:
	145	case CPU_R4650:
	146	case CPU_R4700:
	147	case CPU_R5000:
	148	case CPU_R5500:
	149	case CPU_NEVADA:
	150	case CPU_4KC:
	151	case CPU_4KEC:
	152	case CPU_4KSC:
	153	case CPU_5KC:
	154	case CPU_25KF:
	155	case CPU_PR4450:
	156	case CPU_BMIPS3300:
	157	case CPU_BMIPS4350:
	158	case CPU_BMIPS4380:
	159	case CPU_BMIPS5000:
	160	case CPU_CAVIUM_OCTEON:
	161	case CPU_CAVIUM_OCTEON_PLUS:
	162	case CPU_CAVIUM_OCTEON2:
	163	case CPU_JZRISC:
	164	case CPU_LOONGSON1:
	165	case CPU_XLR:
	166	case CPU_XLP:
	167	cpu_wait = r4k_wait;
	168	break;
	169
	170	case CPU_RM7000:
	171	cpu_wait = rm7k_wait_irqoff;
	172	break;
	173
	174	case CPU_M14KC:
175	case CPU_M14KEC:
176	case CPU_24K:
177	case CPU_34K:
178	case CPU_1004K:
179	cpu_wait = r4k_wait;
180	if (read_c0_config7() & MIPS_CONF7_WII)
181	cpu_wait = r4k_wait_irqoff;
182	break;
183
184	case CPU_74K:
185	cpu_wait = r4k_wait;
186	if ((c->processor_id & 0xff) >= PRID_REV_ENCODE_332(2, 1, 0))
187	cpu_wait = r4k_wait_irqoff;
188	break;
189
190	case CPU_TX49XX:
191	cpu_wait = r4k_wait_irqoff;
192	break;
193	case CPU_ALCHEMY:
194	cpu_wait = au1k_wait;
195	break;
196	case CPU_20KC:
197	/*
198	* WAIT on Rev1.0 has E1, E2, E3 and E16.
199	* WAIT on Rev2.0 and Rev3.0 has E16.
200	* Rev3.1 WAIT is nop, why bother
201	*/
202	if ((c->processor_id & 0xff) <= 0x64)
203	break;
204
205	/*
206	* Another rev is incremeting c0_count at a reduced clock
207	* rate while in WAIT mode. So we basically have the choice
208	* between using the cp0 timer as clocksource or avoiding
209	* the WAIT instruction. Until more details are known,
210	* disable the use of WAIT for 20Kc entirely.
211	cpu_wait = r4k_wait;
212	*/
213	break;
214	case CPU_RM9000:
215	if ((c->processor_id & 0x00ff) >= 0x40)
216	cpu_wait = r4k_wait;
217	break;
218	default:
219	break;
220	}
221	}
222
00baf857	223	static void smtc_idle_hook(void)
49f2ec91 RB	224	{
49f2ec91 RB	225	#ifdef CONFIG_MIPS_MT_SMTC
00baf857	226	void smtc_idle_loop_hook(void);
49f2ec91 RB	227
	228	smtc_idle_loop_hook();
	229	#endif
00baf857 RB	230	}
	231
	232	void arch_cpu_idle(void)
	233	{
	234	smtc_idle_hook();
49f2ec91	235	if (cpu_wait)
c9b6869d	236	cpu_wait();
49f2ec91 RB	237	else
	238	local_irq_enable();
	239	}