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Commit 22d42399 authored by Ben Dooks's avatar Ben Dooks Committed by Ben Dooks
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ARM: S3C2412: CPUFREQ: Add core support. 



Add core support for frequency scaling on the S3C2412 SoC.

Signed-off-by: default avatarBen Dooks <ben@simtec.co.uk>
Signed-off-by: default avatarBen Dooks <ben-linux@fluff.org>
parent baf6b281

arch/arm/mach-s3c2412/Kconfig

+6 −0
Original line number Diff line number Diff line
@@ -32,6 +32,12 @@ config S3C2412_PM 
	help

	  Internal config node to apply S3C2412 power management



config S3C2412_CPUFREQ

	bool

	depends on CPU_FREQ_S3C24XX && CPU_S3C2412

	default y

	help

	  CPU Frequency scaling support for S3C2412 and S3C2413 SoC CPUs.



menu "S3C2412 Machines"

arch/arm/mach-s3c2412/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ obj-$(CONFIG_CPU_S3C2412) += clock.o 
obj-$(CONFIG_CPU_S3C2412)	+= gpio.o

obj-$(CONFIG_S3C2412_DMA)	+= dma.o

obj-$(CONFIG_S3C2412_PM)	+= pm.o sleep.o

obj-$(CONFIG_S3C2412_CPUFREQ)	+= cpu-freq.o



# Machine support

arch/arm/mach-s3c2412/cpu-freq.c

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+251 −0
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/* linux/arch/arm/mach-s3c2412/cpu-freq.c

 *

 * Copyright 2008 Simtec Electronics

 *	http://armlinux.simtec.co.uk/

 *	Ben Dooks <ben@simtec.co.uk>

 *

 * S3C2412 CPU Frequency scalling

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

*/



#include <linux/init.h>

#include <linux/module.h>

#include <linux/interrupt.h>

#include <linux/ioport.h>

#include <linux/cpufreq.h>

#include <linux/sysdev.h>

#include <linux/delay.h>

#include <linux/clk.h>

#include <linux/err.h>

#include <linux/io.h>



#include <asm/mach/arch.h>

#include <asm/mach/map.h>



#include <mach/regs-clock.h>

#include <mach/regs-s3c2412-mem.h>



#include <plat/cpu.h>

#include <plat/clock.h>

#include <plat/cpu-freq-core.h>



/* our clock resources. */

static struct clk *xtal;

static struct clk *fclk;

static struct clk *hclk;

static struct clk *armclk;



/* HDIV: 1, 2, 3, 4, 6, 8 */



static int s3c2412_cpufreq_calcdivs(struct s3c_cpufreq_config *cfg)

{

	unsigned int hdiv, pdiv, armdiv, dvs;

	unsigned long hclk, fclk, armclk, armdiv_clk;

	unsigned long hclk_max;



	fclk = cfg->freq.fclk;

	armclk = cfg->freq.armclk;

	hclk_max = cfg->max.hclk;



	/* We can't run hclk above armclk as at the best we have to

	 * have armclk and hclk in dvs mode. */



	if (hclk_max > armclk)

		hclk_max = armclk;



	s3c_freq_dbg("%s: fclk=%lu, armclk=%lu, hclk_max=%lu\n",

		     __func__, fclk, armclk, hclk_max);

	s3c_freq_dbg("%s: want f=%lu, arm=%lu, h=%lu, p=%lu\n",

		     __func__, cfg->freq.fclk, cfg->freq.armclk,

		     cfg->freq.hclk, cfg->freq.pclk);



	armdiv = fclk / armclk;



	if (armdiv < 1)

		armdiv = 1;

	if (armdiv > 2)

		armdiv = 2;



	cfg->divs.arm_divisor = armdiv;

	armdiv_clk = fclk / armdiv;



	hdiv = armdiv_clk / hclk_max;

	if (hdiv < 1)

		hdiv = 1;



	cfg->freq.hclk = hclk = armdiv_clk / hdiv;



	/* set dvs depending on whether we reached armclk or not. */

	cfg->divs.dvs = dvs = armclk < armdiv_clk;



	/* update the actual armclk we achieved. */

	cfg->freq.armclk = dvs ? hclk : armdiv_clk;



	s3c_freq_dbg("%s: armclk %lu, hclk %lu, armdiv %d, hdiv %d, dvs %d\n",

		     __func__, armclk, hclk, armdiv, hdiv, cfg->divs.dvs);



	if (hdiv > 4)

		goto invalid;



	pdiv = (hclk > cfg->max.pclk) ? 2 : 1;



	if ((hclk / pdiv) > cfg->max.pclk)

		pdiv++;



	cfg->freq.pclk = hclk / pdiv;



	s3c_freq_dbg("%s: pdiv %d\n", __func__, pdiv);



	if (pdiv > 2)

		goto invalid;



	pdiv *= hdiv;



	/* store the result, and then return */



	cfg->divs.h_divisor = hdiv * armdiv;

	cfg->divs.p_divisor = pdiv * armdiv;



	return 0;



 invalid:

	return -EINVAL;

}



static void s3c2412_cpufreq_setdivs(struct s3c_cpufreq_config *cfg)

{

	unsigned long clkdiv;

	unsigned long olddiv;



	olddiv = clkdiv = __raw_readl(S3C2410_CLKDIVN);



	/* clear off current clock info */



	clkdiv &= ~S3C2412_CLKDIVN_ARMDIVN;

	clkdiv &= ~S3C2412_CLKDIVN_HDIVN_MASK;

	clkdiv &= ~S3C2412_CLKDIVN_PDIVN;



	if (cfg->divs.arm_divisor == 2)

		clkdiv |= S3C2412_CLKDIVN_ARMDIVN;



	clkdiv |= ((cfg->divs.h_divisor / cfg->divs.arm_divisor) - 1);



	if (cfg->divs.p_divisor != cfg->divs.h_divisor)

		clkdiv |= S3C2412_CLKDIVN_PDIVN;



	s3c_freq_dbg("%s: div %08lx => %08lx\n", __func__, olddiv, clkdiv);

	__raw_writel(clkdiv, S3C2410_CLKDIVN);



	clk_set_parent(armclk, cfg->divs.dvs ? hclk : fclk);

}



static void s3c2412_cpufreq_setrefresh(struct s3c_cpufreq_config *cfg)

{

	struct s3c_cpufreq_board *board = cfg->board;

	unsigned long refresh;



	s3c_freq_dbg("%s: refresh %u ns, hclk %lu\n", __func__,

		     board->refresh, cfg->freq.hclk);



	/* Reduce both the refresh time (in ns) and the frequency (in MHz)

	 * by 10 each to ensure that we do not overflow 32 bit numbers. This

	 * should work for HCLK up to 133MHz and refresh period up to 30usec.

	 */



	refresh = (board->refresh / 10);

	refresh *= (cfg->freq.hclk / 100);

	refresh /= (1 * 1000 * 1000);	/* 10^6 */



	s3c_freq_dbg("%s: setting refresh 0x%08lx\n", __func__, refresh);

	__raw_writel(refresh, S3C2412_REFRESH);

}



/* set the default cpu frequency information, based on an 200MHz part

 * as we have no other way of detecting the speed rating in software.

 */



static struct s3c_cpufreq_info s3c2412_cpufreq_info = {

	.max		= {

		.fclk	= 200000000,

		.hclk	= 100000000,

		.pclk	=  50000000,

	},



	.latency	= 5000000, /* 5ms */



	.locktime_m	= 150,

	.locktime_u	= 150,

	.locktime_bits	= 16,



	.name		= "s3c2412",

	.set_refresh	= s3c2412_cpufreq_setrefresh,

	.set_divs	= s3c2412_cpufreq_setdivs,

	.calc_divs	= s3c2412_cpufreq_calcdivs,



	.resume_clocks	= s3c2412_setup_clocks,

};



static int s3c2412_cpufreq_add(struct sys_device *sysdev)

{

	unsigned long fclk_rate;



	hclk = clk_get(NULL, "hclk");

	if (IS_ERR(hclk)) {

		printk(KERN_ERR "%s: cannot find hclk clock\n", __func__);

		return -ENOENT;

	}



	fclk = clk_get(NULL, "fclk");

	if (IS_ERR(fclk)) {

		printk(KERN_ERR "%s: cannot find fclk clock\n", __func__);

		goto err_fclk;

	}



	fclk_rate = clk_get_rate(fclk);

	if (fclk_rate > 200000000) {

		printk(KERN_INFO

		       "%s: fclk %ld MHz, assuming 266MHz capable part\n",

		       __func__, fclk_rate / 1000000);

		s3c2412_cpufreq_info.max.fclk = 266000000;

		s3c2412_cpufreq_info.max.hclk = 133000000;

		s3c2412_cpufreq_info.max.pclk =  66000000;

	}



	armclk = clk_get(NULL, "armclk");

	if (IS_ERR(armclk)) {

		printk(KERN_ERR "%s: cannot find arm clock\n", __func__);

		goto err_armclk;

	}



	xtal = clk_get(NULL, "xtal");

	if (IS_ERR(xtal)) {

		printk(KERN_ERR "%s: cannot find xtal clock\n", __func__);

		goto err_xtal;

	}



	return s3c_cpufreq_register(&s3c2412_cpufreq_info);



err_xtal:

	clk_put(armclk);

err_armclk:

	clk_put(fclk);

err_fclk:

	clk_put(hclk);



	return -ENOENT;

}



static struct sysdev_driver s3c2412_cpufreq_driver = {

	.add		= s3c2412_cpufreq_add,

};



static int s3c2412_cpufreq_init(void)

{

	return sysdev_driver_register(&s3c2412_sysclass,

				      &s3c2412_cpufreq_driver);

}



arch_initcall(s3c2412_cpufreq_init);