[mirror_ubuntu-artful-kernel.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/cpu-type.h>
#include <asm/idle.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();
}

void r4k_wait(void)
{
	local_irq_enable();
	__r4k_wait();
}

/*
 * 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	arch=r4000	\n"
		"	wait			\n"
		"	.set	pop		\n");
	local_irq_enable();
}

/*
 * 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	arch=r4000				\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();
}

/*
 * Au1 'wait' is only useful when the 32kHz counter is used as timer,
 * since coreclock (and the cp0 counter) stops upon executing it. Only an
 * interrupt can wake it, so they must be enabled before entering idle modes.
 */
static void au1k_wait(void)
{
	unsigned long c0status = read_c0_status() | 1;	/* irqs on */

	__asm__(
	"	.set	arch=r4000			\n"
	"	cache	0x14, 0(%0)		\n"
	"	cache	0x14, 32(%0)		\n"
	"	sync				\n"
	"	mtc0	%1, $12			\n" /* wr c0status */
	"	wait				\n"
	"	nop				\n"
	"	nop				\n"
	"	nop				\n"
	"	nop				\n"
	"	.set	mips0			\n"
	: : "r" (au1k_wait), "r" (c0status));
}

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 (current_cpu_type()) {
	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_CAVIUM_OCTEON3:
	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:
	case CPU_1074K:
	case CPU_INTERAPTIV:
	case CPU_PROAPTIV:
	case CPU_P5600:
	case CPU_M5150:
		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;
	default:
		break;
	}
}

void arch_cpu_idle(void)
{
	if (cpu_wait)
		cpu_wait();
	else
		local_irq_enable();
}

#ifdef CONFIG_CPU_IDLE

int mips_cpuidle_wait_enter(struct cpuidle_device *dev,
			    struct cpuidle_driver *drv, int index)
{
	arch_cpu_idle();
	return index;
}

#endif
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>
69f24d17	21	#include <asm/cpu-type.h>
bdc92d74	22	#include <asm/idle.h>
49f2ec91 RB	23	#include <asm/mipsregs.h>
	24
	25	/*
	26	* Not all of the MIPS CPUs have the "wait" instruction available. Moreover,
	27	* the implementation of the "wait" feature differs between CPU families. This
	28	* points to the function that implements CPU specific wait.
	29	* The wait instruction stops the pipeline and reduces the power consumption of
	30	* the CPU very much.
	31	*/
	32	void (*cpu_wait)(void);
	33	EXPORT_SYMBOL(cpu_wait);
	34
	35	static void r3081_wait(void)
	36	{
	37	unsigned long cfg = read_c0_conf();
	38	write_c0_conf(cfg \| R30XX_CONF_HALT);
fb40bc3e	39	local_irq_enable();
49f2ec91 RB	40	}
	41
	42	static void r39xx_wait(void)
	43	{
49f2ec91 RB	44	if (!need_resched())
	45	write_c0_conf(read_c0_conf() \| TX39_CONF_HALT);
	46	local_irq_enable();
	47	}
	48
087d990b RB	49	void r4k_wait(void)
	50	{
	51	local_irq_enable();
	52	__r4k_wait();
	53	}
	54
49f2ec91 RB	55	/*
	56	* This variant is preferable as it allows testing need_resched and going to
	57	* sleep depending on the outcome atomically. Unfortunately the "It is
	58	* implementation-dependent whether the pipeline restarts when a non-enabled
	59	* interrupt is requested" restriction in the MIPS32/MIPS64 architecture makes
	60	* using this version a gamble.
	61	*/
	62	void r4k_wait_irqoff(void)
	63	{
49f2ec91	64	if (!need_resched())
f91a148a RB	65	__asm__(
f91a148a RB	66	" .set push \n"
a809d460	67	" .set arch=r4000 \n"
f91a148a RB	68	" wait \n"
f91a148a RB	69	" .set pop \n");
49f2ec91	70	local_irq_enable();
49f2ec91 RB	71	}
	72
	73	/*
	74	* The RM7000 variant has to handle erratum 38. The workaround is to not
	75	* have any pending stores when the WAIT instruction is executed.
	76	*/
	77	static void rm7k_wait_irqoff(void)
	78	{
49f2ec91 RB	79	if (!need_resched())
	80	__asm__(
	81	" .set push \n"
a809d460	82	" .set arch=r4000 \n"
49f2ec91 RB	83	" .set noat \n"
	84	" mfc0 $1, $12 \n"
	85	" sync \n"
	86	" mtc0 $1, $12 # stalls until W stage \n"
	87	" wait \n"
	88	" mtc0 $1, $12 # stalls until W stage \n"
	89	" .set pop \n");
	90	local_irq_enable();
	91	}
	92
	93	/*
e63a24dd ML	94	* Au1 'wait' is only useful when the 32kHz counter is used as timer,
	95	* since coreclock (and the cp0 counter) stops upon executing it. Only an
	96	* interrupt can wake it, so they must be enabled before entering idle modes.
49f2ec91 RB	97	*/
	98	static void au1k_wait(void)
	99	{
e63a24dd ML	100	unsigned long c0status = read_c0_status() \| 1; /* irqs on */
e63a24dd ML	101
f91a148a	102	__asm__(
a809d460	103	" .set arch=r4000 \n"
f91a148a RB	104	" cache 0x14, 0(%0) \n"
	105	" cache 0x14, 32(%0) \n"
	106	" sync \n"
e63a24dd	107	" mtc0 %1, $12 \n" /* wr c0status */
f91a148a RB	108	" wait \n"
	109	" nop \n"
	110	" nop \n"
	111	" nop \n"
	112	" nop \n"
	113	" .set mips0 \n"
e63a24dd	114	: : "r" (au1k_wait), "r" (c0status));
49f2ec91 RB	115	}
	116
	117	static int __initdata nowait;
	118
	119	static int __init wait_disable(char *s)
	120	{
	121	nowait = 1;
	122
	123	return 1;
	124	}
	125
	126	__setup("nowait", wait_disable);
	127
	128	void __init check_wait(void)
	129	{
	130	struct cpuinfo_mips *c = &current_cpu_data;
	131
	132	if (nowait) {
	133	printk("Wait instruction disabled.\n");
	134	return;
	135	}
	136
69f24d17	137	switch (current_cpu_type()) {
49f2ec91 RB	138	case CPU_R3081:
	139	case CPU_R3081E:
	140	cpu_wait = r3081_wait;
	141	break;
	142	case CPU_TX3927:
	143	cpu_wait = r39xx_wait;
	144	break;
	145	case CPU_R4200:
	146	/* case CPU_R4300: */
	147	case CPU_R4600:
	148	case CPU_R4640:
	149	case CPU_R4650:
	150	case CPU_R4700:
	151	case CPU_R5000:
	152	case CPU_R5500:
	153	case CPU_NEVADA:
	154	case CPU_4KC:
	155	case CPU_4KEC:
	156	case CPU_4KSC:
	157	case CPU_5KC:
	158	case CPU_25KF:
	159	case CPU_PR4450:
	160	case CPU_BMIPS3300:
	161	case CPU_BMIPS4350:
	162	case CPU_BMIPS4380:
	163	case CPU_BMIPS5000:
	164	case CPU_CAVIUM_OCTEON:
	165	case CPU_CAVIUM_OCTEON_PLUS:
	166	case CPU_CAVIUM_OCTEON2:
4122af0a	167	case CPU_CAVIUM_OCTEON3:
49f2ec91 RB	168	case CPU_JZRISC:
	169	case CPU_LOONGSON1:
	170	case CPU_XLR:
	171	case CPU_XLP:
	172	cpu_wait = r4k_wait;
	173	break;
	174
	175	case CPU_RM7000:
	176	cpu_wait = rm7k_wait_irqoff;
	177	break;
	178
	179	case CPU_M14KC:
	180	case CPU_M14KEC:
	181	case CPU_24K:
	182	case CPU_34K:
	183	case CPU_1004K:
442e14a2	184	case CPU_1074K:
26ab96df	185	case CPU_INTERAPTIV:
708ac4b8	186	case CPU_PROAPTIV:
aced4cbd	187	case CPU_P5600:
f36c4720	188	case CPU_M5150:
49f2ec91 RB	189	cpu_wait = r4k_wait;
	190	if (read_c0_config7() & MIPS_CONF7_WII)
	191	cpu_wait = r4k_wait_irqoff;
	192	break;
	193
	194	case CPU_74K:
	195	cpu_wait = r4k_wait;
	196	if ((c->processor_id & 0xff) >= PRID_REV_ENCODE_332(2, 1, 0))
	197	cpu_wait = r4k_wait_irqoff;
	198	break;
	199
	200	case CPU_TX49XX:
	201	cpu_wait = r4k_wait_irqoff;
	202	break;
	203	case CPU_ALCHEMY:
	204	cpu_wait = au1k_wait;
	205	break;
	206	case CPU_20KC:
	207	/*
	208	* WAIT on Rev1.0 has E1, E2, E3 and E16.
	209	* WAIT on Rev2.0 and Rev3.0 has E16.
	210	* Rev3.1 WAIT is nop, why bother
	211	*/
	212	if ((c->processor_id & 0xff) <= 0x64)
	213	break;
	214
	215	/*
	216	* Another rev is incremeting c0_count at a reduced clock
	217	* rate while in WAIT mode. So we basically have the choice
	218	* between using the cp0 timer as clocksource or avoiding
	219	* the WAIT instruction. Until more details are known,
	220	* disable the use of WAIT for 20Kc entirely.
	221	cpu_wait = r4k_wait;
	222	*/
	223	break;
49f2ec91 RB	224	default:
	225	break;
	226	}
	227	}
	228
00baf857 RB	229	void arch_cpu_idle(void)
00baf857 RB	230	{
49f2ec91	231	if (cpu_wait)
c9b6869d	232	cpu_wait();
49f2ec91 RB	233	else
	234	local_irq_enable();
	235	}
da9f970f PB	236
	237	#ifdef CONFIG_CPU_IDLE
	238
	239	int mips_cpuidle_wait_enter(struct cpuidle_device *dev,
	240	struct cpuidle_driver *drv, int index)
	241	{
	242	arch_cpu_idle();
	243	return index;
	244	}
	245
	246	#endif