[deliverable/linux.git] / drivers / cpufreq / sa1100-cpufreq.c

/*
 * cpu-sa1100.c: clock scaling for the SA1100
 *
 * Copyright (C) 2000 2001, The Delft University of Technology
 *
 * Authors:
 * - Johan Pouwelse (J.A.Pouwelse@its.tudelft.nl): initial version
 * - Erik Mouw (J.A.K.Mouw@its.tudelft.nl):
 *   - major rewrite for linux-2.3.99
 *   - rewritten for the more generic power management scheme in
 *     linux-2.4.5-rmk1
 *
 * This software has been developed while working on the LART
 * computing board (http://www.lartmaker.nl/), which is
 * sponsored by the Mobile Multi-media Communications
 * (http://www.mobimedia.org/) and Ubiquitous Communications
 * (http://www.ubicom.tudelft.nl/) projects.
 *
 * The authors can be reached at:
 *
 *  Erik Mouw
 *  Information and Communication Theory Group
 *  Faculty of Information Technology and Systems
 *  Delft University of Technology
 *  P.O. Box 5031
 *  2600 GA Delft
 *  The Netherlands
 *
 *
 * 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
 *
 *
 * Theory of operations
 * ====================
 *
 * Clock scaling can be used to lower the power consumption of the CPU
 * core. This will give you a somewhat longer running time.
 *
 * The SA-1100 has a single register to change the core clock speed:
 *
 *   PPCR      0x90020014    PLL config
 *
 * However, the DRAM timings are closely related to the core clock
 * speed, so we need to change these, too. The used registers are:
 *
 *   MDCNFG    0xA0000000    DRAM config
 *   MDCAS0    0xA0000004    Access waveform
 *   MDCAS1    0xA0000008    Access waveform
 *   MDCAS2    0xA000000C    Access waveform
 *
 * Care must be taken to change the DRAM parameters the correct way,
 * because otherwise the DRAM becomes unusable and the kernel will
 * crash.
 *
 * The simple solution to avoid a kernel crash is to put the actual
 * clock change in ROM and jump to that code from the kernel. The main
 * disadvantage is that the ROM has to be modified, which is not
 * possible on all SA-1100 platforms. Another disadvantage is that
 * jumping to ROM makes clock switching unnecessary complicated.
 *
 * The idea behind this driver is that the memory configuration can be
 * changed while running from DRAM (even with interrupts turned on!)
 * as long as all re-configuration steps yield a valid DRAM
 * configuration. The advantages are clear: it will run on all SA-1100
 * platforms, and the code is very simple.
 *
 * If you really want to understand what is going on in
 * sa1100_update_dram_timings(), you'll have to read sections 8.2,
 * 9.5.7.3, and 10.2 from the "Intel StrongARM SA-1100 Microprocessor
 * Developers Manual" (available for free from Intel).
 *
 */

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/io.h>

#include <asm/cputype.h>

#include <mach/generic.h>
#include <mach/hardware.h>

struct sa1100_dram_regs {
	int speed;
	u32 mdcnfg;
	u32 mdcas0;
	u32 mdcas1;
	u32 mdcas2;
};


static struct cpufreq_driver sa1100_driver;

static struct sa1100_dram_regs sa1100_dram_settings[] = {
	/*speed,     mdcnfg,     mdcas0,     mdcas1,     mdcas2,   clock freq */
	{ 59000, 0x00dc88a3, 0xcccccccf, 0xfffffffc, 0xffffffff},/*  59.0 MHz */
	{ 73700, 0x011490a3, 0xcccccccf, 0xfffffffc, 0xffffffff},/*  73.7 MHz */
	{ 88500, 0x014e90a3, 0xcccccccf, 0xfffffffc, 0xffffffff},/*  88.5 MHz */
	{103200, 0x01889923, 0xcccccccf, 0xfffffffc, 0xffffffff},/* 103.2 MHz */
	{118000, 0x01c29923, 0x9999998f, 0xfffffff9, 0xffffffff},/* 118.0 MHz */
	{132700, 0x01fb2123, 0x9999998f, 0xfffffff9, 0xffffffff},/* 132.7 MHz */
	{147500, 0x02352123, 0x3333330f, 0xfffffff3, 0xffffffff},/* 147.5 MHz */
	{162200, 0x026b29a3, 0x38e38e1f, 0xfff8e38e, 0xffffffff},/* 162.2 MHz */
	{176900, 0x02a329a3, 0x71c71c1f, 0xfff1c71c, 0xffffffff},/* 176.9 MHz */
	{191700, 0x02dd31a3, 0xe38e383f, 0xffe38e38, 0xffffffff},/* 191.7 MHz */
	{206400, 0x03153223, 0xc71c703f, 0xffc71c71, 0xffffffff},/* 206.4 MHz */
	{221200, 0x034fba23, 0xc71c703f, 0xffc71c71, 0xffffffff},/* 221.2 MHz */
	{235900, 0x03853a23, 0xe1e1e07f, 0xe1e1e1e1, 0xffffffe1},/* 235.9 MHz */
	{250700, 0x03bf3aa3, 0xc3c3c07f, 0xc3c3c3c3, 0xffffffc3},/* 250.7 MHz */
	{265400, 0x03f7c2a3, 0xc3c3c07f, 0xc3c3c3c3, 0xffffffc3},/* 265.4 MHz */
	{280200, 0x0431c2a3, 0x878780ff, 0x87878787, 0xffffff87},/* 280.2 MHz */
	{ 0, 0, 0, 0, 0 } /* last entry */
};

static void sa1100_update_dram_timings(int current_speed, int new_speed)
{
	struct sa1100_dram_regs *settings = sa1100_dram_settings;

	/* find speed */
	while (settings->speed != 0) {
		if (new_speed == settings->speed)
			break;

		settings++;
	}

	if (settings->speed == 0) {
		panic("%s: couldn't find dram setting for speed %d\n",
		      __func__, new_speed);
	}

	/* No risk, no fun: run with interrupts on! */
	if (new_speed > current_speed) {
		/* We're going FASTER, so first relax the memory
		 * timings before changing the core frequency
		 */

		/* Half the memory access clock */
		MDCNFG |= MDCNFG_CDB2;

		/* The order of these statements IS important, keep 8
		 * pulses!!
		 */
		MDCAS2 = settings->mdcas2;
		MDCAS1 = settings->mdcas1;
		MDCAS0 = settings->mdcas0;
		MDCNFG = settings->mdcnfg;
	} else {
		/* We're going SLOWER: first decrease the core
		 * frequency and then tighten the memory settings.
		 */

		/* Half the memory access clock */
		MDCNFG |= MDCNFG_CDB2;

		/* The order of these statements IS important, keep 8
		 * pulses!!
		 */
		MDCAS0 = settings->mdcas0;
		MDCAS1 = settings->mdcas1;
		MDCAS2 = settings->mdcas2;
		MDCNFG = settings->mdcnfg;
	}
}

static int sa1100_target(struct cpufreq_policy *policy, unsigned int ppcr)
{
	unsigned int cur = sa11x0_getspeed(0);
	unsigned int new_freq;

	new_freq = sa11x0_freq_table[ppcr].frequency;

	if (new_freq > cur)
		sa1100_update_dram_timings(cur, new_freq);

	PPCR = ppcr;

	if (new_freq < cur)
		sa1100_update_dram_timings(cur, new_freq);

	return 0;
}

static int __init sa1100_cpu_init(struct cpufreq_policy *policy)
{
	return cpufreq_generic_init(policy, sa11x0_freq_table, CPUFREQ_ETERNAL);
}

static struct cpufreq_driver sa1100_driver __refdata = {
	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
	.verify		= cpufreq_generic_frequency_table_verify,
	.target_index	= sa1100_target,
	.get		= sa11x0_getspeed,
	.init		= sa1100_cpu_init,
	.name		= "sa1100",
};

static int __init sa1100_dram_init(void)
{
	if (cpu_is_sa1100())
		return cpufreq_register_driver(&sa1100_driver);
	else
		return -ENODEV;
}

arch_initcall(sa1100_dram_init);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* cpu-sa1100.c: clock scaling for the SA1100
	3	*
	4	* Copyright (C) 2000 2001, The Delft University of Technology
	5	*
93982535	6	* Authors:
1da177e4 LT	7	* - Johan Pouwelse (J.A.Pouwelse@its.tudelft.nl): initial version
	8	* - Erik Mouw (J.A.K.Mouw@its.tudelft.nl):
	9	* - major rewrite for linux-2.3.99
93982535	10	* - rewritten for the more generic power management scheme in
1da177e4 LT	11	* linux-2.4.5-rmk1
	12	*
	13	* This software has been developed while working on the LART
c8c4b939	14	* computing board (http://www.lartmaker.nl/), which is
1da177e4	15	* sponsored by the Mobile Multi-media Communications
50a23e6e	16	* (http://www.mobimedia.org/) and Ubiquitous Communications
1da177e4 LT	17	* (http://www.ubicom.tudelft.nl/) projects.
	18	*
	19	* The authors can be reached at:
	20	*
	21	* Erik Mouw
	22	* Information and Communication Theory Group
	23	* Faculty of Information Technology and Systems
	24	* Delft University of Technology
	25	* P.O. Box 5031
	26	* 2600 GA Delft
	27	* The Netherlands
	28	*
	29	*
	30	* This program is free software; you can redistribute it and/or modify
	31	* it under the terms of the GNU General Public License as published by
	32	* the Free Software Foundation; either version 2 of the License, or
	33	* (at your option) any later version.
	34	*
	35	* This program is distributed in the hope that it will be useful,
	36	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	37	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	38	* GNU General Public License for more details.
93982535	39	*
1da177e4 LT	40	* You should have received a copy of the GNU General Public License
	41	* along with this program; if not, write to the Free Software
	42	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	43	*
	44	*
	45	* Theory of operations
	46	* ====================
93982535	47	*
1da177e4 LT	48	* Clock scaling can be used to lower the power consumption of the CPU
	49	* core. This will give you a somewhat longer running time.
	50	*
	51	* The SA-1100 has a single register to change the core clock speed:
	52	*
	53	* PPCR 0x90020014 PLL config
	54	*
	55	* However, the DRAM timings are closely related to the core clock
	56	* speed, so we need to change these, too. The used registers are:
	57	*
	58	* MDCNFG 0xA0000000 DRAM config
	59	* MDCAS0 0xA0000004 Access waveform
	60	* MDCAS1 0xA0000008 Access waveform
93982535	61	* MDCAS2 0xA000000C Access waveform
1da177e4 LT	62	*
	63	* Care must be taken to change the DRAM parameters the correct way,
	64	* because otherwise the DRAM becomes unusable and the kernel will
93982535	65	* crash.
1da177e4 LT	66	*
	67	* The simple solution to avoid a kernel crash is to put the actual
	68	* clock change in ROM and jump to that code from the kernel. The main
	69	* disadvantage is that the ROM has to be modified, which is not
	70	* possible on all SA-1100 platforms. Another disadvantage is that
25985edc	71	* jumping to ROM makes clock switching unnecessary complicated.
1da177e4 LT	72	*
	73	* The idea behind this driver is that the memory configuration can be
	74	* changed while running from DRAM (even with interrupts turned on!)
	75	* as long as all re-configuration steps yield a valid DRAM
	76	* configuration. The advantages are clear: it will run on all SA-1100
	77	* platforms, and the code is very simple.
93982535	78	*
1da177e4 LT	79	* If you really want to understand what is going on in
	80	* sa1100_update_dram_timings(), you'll have to read sections 8.2,
	81	* 9.5.7.3, and 10.2 from the "Intel StrongARM SA-1100 Microprocessor
	82	* Developers Manual" (available for free from Intel).
	83	*
	84	*/
	85
	86	#include <linux/kernel.h>
	87	#include <linux/types.h>
	88	#include <linux/init.h>
	89	#include <linux/cpufreq.h>
3169663a	90	#include <linux/io.h>
1da177e4	91
0ba8b9b2 RK	92	#include <asm/cputype.h>
0ba8b9b2 RK	93
59a2e613	94	#include <mach/generic.h>
a09e64fb	95	#include <mach/hardware.h>
1da177e4	96
d03f322c	97	struct sa1100_dram_regs {
1da177e4 LT	98	int speed;
1da177e4 LT	99	u32 mdcnfg;
93982535	100	u32 mdcas0;
1da177e4 LT	101	u32 mdcas1;
1da177e4 LT	102	u32 mdcas2;
d03f322c	103	};
1da177e4 LT	104
	105
	106	static struct cpufreq_driver sa1100_driver;
	107
d03f322c MRJ	108	static struct sa1100_dram_regs sa1100_dram_settings[] = {
	109	/speed, mdcnfg, mdcas0, mdcas1, mdcas2, clock freq /
	110	{ 59000, 0x00dc88a3, 0xcccccccf, 0xfffffffc, 0xffffffff},/* 59.0 MHz */
	111	{ 73700, 0x011490a3, 0xcccccccf, 0xfffffffc, 0xffffffff},/* 73.7 MHz */
	112	{ 88500, 0x014e90a3, 0xcccccccf, 0xfffffffc, 0xffffffff},/* 88.5 MHz */
	113	{103200, 0x01889923, 0xcccccccf, 0xfffffffc, 0xffffffff},/* 103.2 MHz */
	114	{118000, 0x01c29923, 0x9999998f, 0xfffffff9, 0xffffffff},/* 118.0 MHz */
	115	{132700, 0x01fb2123, 0x9999998f, 0xfffffff9, 0xffffffff},/* 132.7 MHz */
	116	{147500, 0x02352123, 0x3333330f, 0xfffffff3, 0xffffffff},/* 147.5 MHz */
	117	{162200, 0x026b29a3, 0x38e38e1f, 0xfff8e38e, 0xffffffff},/* 162.2 MHz */
	118	{176900, 0x02a329a3, 0x71c71c1f, 0xfff1c71c, 0xffffffff},/* 176.9 MHz */
	119	{191700, 0x02dd31a3, 0xe38e383f, 0xffe38e38, 0xffffffff},/* 191.7 MHz */
	120	{206400, 0x03153223, 0xc71c703f, 0xffc71c71, 0xffffffff},/* 206.4 MHz */
	121	{221200, 0x034fba23, 0xc71c703f, 0xffc71c71, 0xffffffff},/* 221.2 MHz */
	122	{235900, 0x03853a23, 0xe1e1e07f, 0xe1e1e1e1, 0xffffffe1},/* 235.9 MHz */
	123	{250700, 0x03bf3aa3, 0xc3c3c07f, 0xc3c3c3c3, 0xffffffc3},/* 250.7 MHz */
	124	{265400, 0x03f7c2a3, 0xc3c3c07f, 0xc3c3c3c3, 0xffffffc3},/* 265.4 MHz */
	125	{280200, 0x0431c2a3, 0x878780ff, 0x87878787, 0xffffff87},/* 280.2 MHz */
1da177e4 LT	126	{ 0, 0, 0, 0, 0 } /* last entry */
	127	};
	128
	129	static void sa1100_update_dram_timings(int current_speed, int new_speed)
	130	{
d03f322c	131	struct sa1100_dram_regs *settings = sa1100_dram_settings;
1da177e4 LT	132
	133	/* find speed */
	134	while (settings->speed != 0) {
d03f322c	135	if (new_speed == settings->speed)
1da177e4	136	break;
d03f322c	137
1da177e4 LT	138	settings++;
	139	}
	140
	141	if (settings->speed == 0) {
	142	panic("%s: couldn't find dram setting for speed %d\n",
8e86f427	143	__func__, new_speed);
1da177e4 LT	144	}
	145
	146	/* No risk, no fun: run with interrupts on! */
	147	if (new_speed > current_speed) {
	148	/* We're going FASTER, so first relax the memory
93982535	149	* timings before changing the core frequency
1da177e4	150	*/
d03f322c	151
1da177e4 LT	152	/* Half the memory access clock */
	153	MDCNFG \|= MDCNFG_CDB2;
	154
	155	/* The order of these statements IS important, keep 8
	156	* pulses!!
	157	*/
	158	MDCAS2 = settings->mdcas2;
	159	MDCAS1 = settings->mdcas1;
	160	MDCAS0 = settings->mdcas0;
	161	MDCNFG = settings->mdcnfg;
	162	} else {
	163	/* We're going SLOWER: first decrease the core
	164	* frequency and then tighten the memory settings.
	165	*/
	166
	167	/* Half the memory access clock */
	168	MDCNFG \|= MDCNFG_CDB2;
	169
	170	/* The order of these statements IS important, keep 8
	171	* pulses!!
	172	*/
	173	MDCAS0 = settings->mdcas0;
	174	MDCAS1 = settings->mdcas1;
	175	MDCAS2 = settings->mdcas2;
	176	MDCNFG = settings->mdcnfg;
	177	}
	178	}
	179
9c0ebcf7	180	static int sa1100_target(struct cpufreq_policy *policy, unsigned int ppcr)
1da177e4 LT	181	{
1da177e4 LT	182	unsigned int cur = sa11x0_getspeed(0);
d4019f0a	183	unsigned int new_freq;
521e9549	184
d4019f0a	185	new_freq = sa11x0_freq_table[ppcr].frequency;
1da177e4	186
d4019f0a VK	187	if (new_freq > cur)
d4019f0a VK	188	sa1100_update_dram_timings(cur, new_freq);
1da177e4	189
9c0ebcf7	190	PPCR = ppcr;
1da177e4	191
d4019f0a VK	192	if (new_freq < cur)
d4019f0a VK	193	sa1100_update_dram_timings(cur, new_freq);
1da177e4 LT	194
	195	return 0;
	196	}
	197
	198	static int __init sa1100_cpu_init(struct cpufreq_policy *policy)
	199	{
9b30367b	200	return cpufreq_generic_init(policy, sa11x0_freq_table, CPUFREQ_ETERNAL);
1da177e4 LT	201	}
1da177e4 LT	202
7a28b5a2	203	static struct cpufreq_driver sa1100_driver __refdata = {
ae6b4271	204	.flags = CPUFREQ_STICKY \| CPUFREQ_NEED_INITIAL_FREQ_CHECK,
dd9f2639	205	.verify = cpufreq_generic_frequency_table_verify,
9c0ebcf7	206	.target_index = sa1100_target,
1da177e4 LT	207	.get = sa11x0_getspeed,
	208	.init = sa1100_cpu_init,
	209	.name = "sa1100",
	210	};
	211
	212	static int __init sa1100_dram_init(void)
	213	{
0ba8b9b2	214	if (cpu_is_sa1100())
1da177e4 LT	215	return cpufreq_register_driver(&sa1100_driver);
	216	else
	217	return -ENODEV;
	218	}
	219
	220	arch_initcall(sa1100_dram_init);