Commit 9e2697ff authored by Russell King's avatar Russell King Committed by Russell King
Browse files

[ARM] pxa: add cpufreq support 



There have been patches hanging around for ages to add support for
cpufreq to PXA255 processors.  It's about time we applied one.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent cae05541

Documentation/cpu-freq/user-guide.txt

+1 −0
Original line number Diff line number Diff line
@@ -45,6 +45,7 @@ The following ARM processors are supported by cpufreq: 
ARM Integrator

ARM-SA1100

ARM-SA1110

Intel PXA





1.2 x86

arch/arm/Kconfig

+7 −1
Original line number Diff line number Diff line
@@ -868,7 +868,7 @@ config KEXEC 


endmenu



if (ARCH_SA1100 || ARCH_INTEGRATOR || ARCH_OMAP || ARCH_IMX )

if (ARCH_SA1100 || ARCH_INTEGRATOR || ARCH_OMAP || ARCH_IMX || ARCH_PXA)



menu "CPU Frequency scaling"
@@ -904,6 +904,12 @@ config CPU_FREQ_IMX 


	  If in doubt, say N.



config CPU_FREQ_PXA

	bool

	depends on CPU_FREQ && ARCH_PXA && PXA25x

	default y

	select CPU_FREQ_DEFAULT_GOV_USERSPACE



endmenu



endif

arch/arm/mach-pxa/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ obj-$(CONFIG_LEDS) += $(led-y) 


# Misc features

obj-$(CONFIG_PM)		+= pm.o sleep.o

obj-$(CONFIG_CPU_FREQ)		+= cpu-pxa.o

obj-$(CONFIG_PXA_SSP)		+= ssp.o



ifeq ($(CONFIG_PXA27x),y)

arch/arm/mach-pxa/cpu-pxa.c

0 → 100644
+293 −0
Original line number Diff line number Diff line 
/*

 *  linux/arch/arm/mach-pxa/cpu-pxa.c

 *

 *  Copyright (C) 2002,2003 Intrinsyc Software

 *

 * 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.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 *

 * History:

 *   31-Jul-2002 : Initial version [FB]

 *   29-Jan-2003 : added PXA255 support [FB]

 *   20-Apr-2003 : ported to v2.5 (Dustin McIntire, Sensoria Corp.)

 *

 * Note:

 *   This driver may change the memory bus clock rate, but will not do any

 *   platform specific access timing changes... for example if you have flash

 *   memory connected to CS0, you will need to register a platform specific

 *   notifier which will adjust the memory access strobes to maintain a

 *   minimum strobe width.

 *

 */



#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/sched.h>

#include <linux/init.h>

#include <linux/cpufreq.h>



#include <asm/hardware.h>

#include <asm/arch/pxa-regs.h>



#ifdef DEBUG

static unsigned int freq_debug;

MODULE_PARM(freq_debug, "i");

MODULE_PARM_DESC(freq_debug, "Set the debug messages to on=1/off=0");

#else

#define freq_debug  0

#endif



typedef struct {

	unsigned int khz;

	unsigned int membus;

	unsigned int cccr;

	unsigned int div2;

} pxa_freqs_t;



/* Define the refresh period in mSec for the SDRAM and the number of rows */

#define SDRAM_TREF          64      /* standard 64ms SDRAM */

#define SDRAM_ROWS          4096    /* 64MB=8192 32MB=4096 */

#define MDREFR_DRI(x)       (((x) * SDRAM_TREF) / (SDRAM_ROWS * 32))



#define CCLKCFG_TURBO       0x1

#define CCLKCFG_FCS         0x2

#define PXA25x_MIN_FREQ     99500

#define PXA25x_MAX_FREQ     398100

#define MDREFR_DB2_MASK     (MDREFR_K2DB2 | MDREFR_K1DB2)

#define MDREFR_DRI_MASK     0xFFF





/* Use the run mode frequencies for the CPUFREQ_POLICY_PERFORMANCE policy */

static pxa_freqs_t pxa255_run_freqs[] =

{

    /* CPU   MEMBUS  CCCR  DIV2*/

    { 99500,  99500, 0x121, 1}, /* run= 99, turbo= 99, PXbus=50,  SDRAM=50 */

    {132700, 132700, 0x123, 1}, /* run=133, turbo=133, PXbus=66,  SDRAM=66 */

    {199100,  99500, 0x141, 0}, /* run=199, turbo=199, PXbus=99,  SDRAM=99 */

    {265400, 132700, 0x143, 1}, /* run=265, turbo=265, PXbus=133, SDRAM=66 */

    {331800, 165900, 0x145, 1}, /* run=331, turbo=331, PXbus=166, SDRAM=83 */

    {398100,  99500, 0x161, 0}, /* run=398, turbo=398, PXbus=196, SDRAM=99 */

    {0,}

};

#define NUM_RUN_FREQS ARRAY_SIZE(pxa255_run_freqs)



static struct cpufreq_frequency_table pxa255_run_freq_table[NUM_RUN_FREQS+1];



/* Use the turbo mode frequencies for the CPUFREQ_POLICY_POWERSAVE policy */

static pxa_freqs_t pxa255_turbo_freqs[] =

{

    /* CPU   MEMBUS  CCCR  DIV2*/

    { 99500, 99500,  0x121, 1}, /* run=99,  turbo= 99, PXbus=50, SDRAM=50 */

    {199100, 99500,  0x221, 0}, /* run=99,  turbo=199, PXbus=50, SDRAM=99 */

    {298500, 99500,  0x321, 0}, /* run=99,  turbo=287, PXbus=50, SDRAM=99 */

    {298600, 99500,  0x1c1, 0}, /* run=199, turbo=287, PXbus=99, SDRAM=99 */

    {398100, 99500,  0x241, 0}, /* run=199, turbo=398, PXbus=99, SDRAM=99 */

    {0,}

};

#define NUM_TURBO_FREQS ARRAY_SIZE(pxa255_turbo_freqs)



static struct cpufreq_frequency_table pxa255_turbo_freq_table[NUM_TURBO_FREQS+1];



extern unsigned get_clk_frequency_khz(int info);



/* find a valid frequency point */

static int pxa_verify_policy(struct cpufreq_policy *policy)

{

	struct cpufreq_frequency_table *pxa_freqs_table;

	int ret;



	if (policy->policy == CPUFREQ_POLICY_PERFORMANCE) {

		pxa_freqs_table = pxa255_run_freq_table;

	} else if (policy->policy == CPUFREQ_POLICY_POWERSAVE) {

		pxa_freqs_table = pxa255_turbo_freq_table;

	} else {

		printk("CPU PXA: Unknown policy found. "

		       "Using CPUFREQ_POLICY_PERFORMANCE\n");

		pxa_freqs_table = pxa255_run_freq_table;

	}



	ret = cpufreq_frequency_table_verify(policy, pxa_freqs_table);



	if (freq_debug)

		pr_debug("Verified CPU policy: %dKhz min to %dKhz max\n",

		       policy->min, policy->max);



	return ret;

}



static int pxa_set_target(struct cpufreq_policy *policy,

			   unsigned int target_freq,

			   unsigned int relation)

{

	struct cpufreq_frequency_table *pxa_freqs_table;

	pxa_freqs_t *pxa_freq_settings;

	struct cpufreq_freqs freqs;

	int idx;

	unsigned long flags;

	unsigned int unused, preset_mdrefr, postset_mdrefr;

	void *ramstart = phys_to_virt(0xa0000000);



	/* Get the current policy */

	if (policy->policy == CPUFREQ_POLICY_PERFORMANCE) {

		pxa_freq_settings = pxa255_run_freqs;

		pxa_freqs_table   = pxa255_run_freq_table;

	} else if (policy->policy == CPUFREQ_POLICY_POWERSAVE) {

		pxa_freq_settings = pxa255_turbo_freqs;

		pxa_freqs_table   = pxa255_turbo_freq_table;

	} else {

		printk("CPU PXA: Unknown policy found. "

		       "Using CPUFREQ_POLICY_PERFORMANCE\n");

		pxa_freq_settings = pxa255_run_freqs;

		pxa_freqs_table   = pxa255_run_freq_table;

	}



	/* Lookup the next frequency */

	if (cpufreq_frequency_table_target(policy, pxa_freqs_table,

	                                   target_freq, relation, &idx)) {

		return -EINVAL;

	}



	freqs.old = policy->cur;

	freqs.new = pxa_freq_settings[idx].khz;

	freqs.cpu = policy->cpu;



	if (freq_debug)

		pr_debug(KERN_INFO "Changing CPU frequency to %d Mhz, (SDRAM %d Mhz)\n",

		       freqs.new / 1000, (pxa_freq_settings[idx].div2) ?

		       (pxa_freq_settings[idx].membus / 2000) :

		       (pxa_freq_settings[idx].membus / 1000));



	/*

	 * Tell everyone what we're about to do...

	 * you should add a notify client with any platform specific

	 * Vcc changing capability

	 */

	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);



	/* Calculate the next MDREFR.  If we're slowing down the SDRAM clock

	 * we need to preset the smaller DRI before the change.  If we're speeding

	 * up we need to set the larger DRI value after the change.

	 */

	preset_mdrefr = postset_mdrefr = MDREFR;

	if ((MDREFR & MDREFR_DRI_MASK) > MDREFR_DRI(pxa_freq_settings[idx].membus)) {

		preset_mdrefr = (preset_mdrefr & ~MDREFR_DRI_MASK) |

		                MDREFR_DRI(pxa_freq_settings[idx].membus);

	}

	postset_mdrefr = (postset_mdrefr & ~MDREFR_DRI_MASK) |

		            MDREFR_DRI(pxa_freq_settings[idx].membus);



	/* If we're dividing the memory clock by two for the SDRAM clock, this

	 * must be set prior to the change.  Clearing the divide must be done

	 * after the change.

	 */

	if (pxa_freq_settings[idx].div2) {

		preset_mdrefr  |= MDREFR_DB2_MASK;

		postset_mdrefr |= MDREFR_DB2_MASK;

	} else {

		postset_mdrefr &= ~MDREFR_DB2_MASK;

	}



	local_irq_save(flags);



	/* Set new the CCCR */

	CCCR = pxa_freq_settings[idx].cccr;



	asm volatile("							\n\

		ldr	r4, [%1]		/* load MDREFR */	\n\

		b	2f						\n\

		.align	5 						\n\

1:									\n\

		str	%4, [%1]		/* preset the MDREFR */	\n\

		mcr	p14, 0, %2, c6, c0, 0	/* set CCLKCFG[FCS] */	\n\

		str	%5, [%1]		/* postset the MDREFR */ \n\

									\n\

		b	3f						\n\

2:		b	1b						\n\

3:		nop							\n\

	  "

	  : "=&r" (unused)

	  : "r" (&MDREFR), "r" (CCLKCFG_TURBO|CCLKCFG_FCS), "r" (ramstart),

	    "r" (preset_mdrefr), "r" (postset_mdrefr)

	  : "r4", "r5");

	local_irq_restore(flags);



	/*

	 * Tell everyone what we've just done...

	 * you should add a notify client with any platform specific

	 * SDRAM refresh timer adjustments

	 */

	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);



	return 0;

}



static int pxa_cpufreq_init(struct cpufreq_policy *policy)

{

	int i;



	/* set default policy and cpuinfo */

	policy->governor = CPUFREQ_DEFAULT_GOVERNOR;

	policy->policy = CPUFREQ_POLICY_PERFORMANCE;

	policy->cpuinfo.max_freq = PXA25x_MAX_FREQ;

	policy->cpuinfo.min_freq = PXA25x_MIN_FREQ;

	policy->cpuinfo.transition_latency = 1000; /* FIXME: 1 ms, assumed */

	policy->cur = get_clk_frequency_khz(0);    /* current freq */

	policy->min = policy->max = policy->cur;



	/* Generate the run cpufreq_frequency_table struct */

	for (i = 0; i < NUM_RUN_FREQS; i++) {

		pxa255_run_freq_table[i].frequency = pxa255_run_freqs[i].khz;

		pxa255_run_freq_table[i].index = i;

	}



	pxa255_run_freq_table[i].frequency = CPUFREQ_TABLE_END;

	/* Generate the turbo cpufreq_frequency_table struct */

	for (i = 0; i < NUM_TURBO_FREQS; i++) {

		pxa255_turbo_freq_table[i].frequency = pxa255_turbo_freqs[i].khz;

		pxa255_turbo_freq_table[i].index = i;

	}

	pxa255_turbo_freq_table[i].frequency = CPUFREQ_TABLE_END;



	printk(KERN_INFO "PXA CPU frequency change support initialized\n");



	return 0;

}



static struct cpufreq_driver pxa_cpufreq_driver = {

	.verify	= pxa_verify_policy,

	.target	= pxa_set_target,

	.init	= pxa_cpufreq_init,

	.name	= "PXA25x",

};



static int __init pxa_cpu_init(void)

{

	int ret = -ENODEV;

	if (cpu_is_pxa25x())

		ret = cpufreq_register_driver(&pxa_cpufreq_driver);

	return ret;

}



static void __exit pxa_cpu_exit(void)

{

	if (cpu_is_pxa25x())

		cpufreq_unregister_driver(&pxa_cpufreq_driver);

}





MODULE_AUTHOR ("Intrinsyc Software Inc.");

MODULE_DESCRIPTION ("CPU frequency changing driver for the PXA architecture");

MODULE_LICENSE("GPL");

module_init(pxa_cpu_init);

module_exit(pxa_cpu_exit);