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/*
 * Copyright (C) 2007 PA Semi, Inc
 *
 * Authors: Egor Martovetsky <egor@pasemi.com>
 *	    Olof Johansson <olof@lixom.net>
 *
 * Maintained by: Olof Johansson <olof@lixom.net>
 *
 * Based on arch/powerpc/platforms/cell/cbe_cpufreq.c:
 * (C) Copyright IBM Deutschland Entwicklung GmbH 2005
 *
 * 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, 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <linux/cpufreq.h>
#include <linux/timer.h>
#include <linux/module.h>
#include <linux/of_address.h>

#include <asm/hw_irq.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/time.h>
#include <asm/smp.h>

#define SDCASR_REG		0x0100
#define SDCASR_REG_STRIDE	0x1000
#define SDCPWR_CFGA0_REG	0x0100
#define SDCPWR_PWST0_REG	0x0000
#define SDCPWR_GIZTIME_REG	0x0440

/* SDCPWR_GIZTIME_REG fields */
#define SDCPWR_GIZTIME_GR	0x80000000
#define SDCPWR_GIZTIME_LONGLOCK	0x000000ff

/* Offset of ASR registers from SDC base */
#define SDCASR_OFFSET		0x120000

static void __iomem *sdcpwr_mapbase;
static void __iomem *sdcasr_mapbase;

/* Current astate, is used when waking up from power savings on
 * one core, in case the other core has switched states during
 * the idle time.
 */
static int current_astate;

/* We support 5(A0-A4) power states excluding turbo(A5-A6) modes */
static struct cpufreq_frequency_table pas_freqs[] = {
	{0, 0,	0},
	{0, 1,	0},
	{0, 2,	0},
	{0, 3,	0},
	{0, 4,	0},
	{0, 0,	CPUFREQ_TABLE_END},
};

/*
 * hardware specific functions
 */

static int get_astate_freq(int astate)
{
	u32 ret;
	ret = in_le32(sdcpwr_mapbase + SDCPWR_CFGA0_REG + (astate * 0x10));

	return ret & 0x3f;
}

static int get_cur_astate(int cpu)
{
	u32 ret;

	ret = in_le32(sdcpwr_mapbase + SDCPWR_PWST0_REG);
	ret = (ret >> (cpu * 4)) & 0x7;

	return ret;
}

static int get_gizmo_latency(void)
{
	u32 giztime, ret;

	giztime = in_le32(sdcpwr_mapbase + SDCPWR_GIZTIME_REG);

	/* just provide the upper bound */
	if (giztime & SDCPWR_GIZTIME_GR)
		ret = (giztime & SDCPWR_GIZTIME_LONGLOCK) * 128000;
	else
		ret = (giztime & SDCPWR_GIZTIME_LONGLOCK) * 1000;

	return ret;
}

static void set_astate(int cpu, unsigned int astate)
{
	unsigned long flags;

	/* Return if called before init has run */
	if (unlikely(!sdcasr_mapbase))
		return;

	local_irq_save(flags);

	out_le32(sdcasr_mapbase + SDCASR_REG + SDCASR_REG_STRIDE*cpu, astate);

	local_irq_restore(flags);
}

int check_astate(void)
{
	return get_cur_astate(hard_smp_processor_id());
}

void restore_astate(int cpu)
{
	set_astate(cpu, current_astate);
}

/*
 * cpufreq functions
 */

static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
	struct cpufreq_frequency_table *pos;
	const u32 *max_freqp;
	u32 max_freq;
	int cur_astate;
	struct resource res;
	struct device_node *cpu, *dn;
	int err = -ENODEV;

	cpu = of_get_cpu_node(policy->cpu, NULL);

	if (!cpu)
		goto out;

	dn = of_find_compatible_node(NULL, NULL, "1682m-sdc");
	if (!dn)
		dn = of_find_compatible_node(NULL, NULL,
					     "pasemi,pwrficient-sdc");
	if (!dn)
		goto out;
	err = of_address_to_resource(dn, 0, &res);
	of_node_put(dn);
	if (err)
		goto out;
	sdcasr_mapbase = ioremap(res.start + SDCASR_OFFSET, 0x2000);
	if (!sdcasr_mapbase) {
		err = -EINVAL;
		goto out;
	}

	dn = of_find_compatible_node(NULL, NULL, "1682m-gizmo");
	if (!dn)
		dn = of_find_compatible_node(NULL, NULL,
					     "pasemi,pwrficient-gizmo");
	if (!dn) {
		err = -ENODEV;
		goto out_unmap_sdcasr;
	}
	err = of_address_to_resource(dn, 0, &res);
	of_node_put(dn);
	if (err)
		goto out_unmap_sdcasr;
	sdcpwr_mapbase = ioremap(res.start, 0x1000);
	if (!sdcpwr_mapbase) {
		err = -EINVAL;
		goto out_unmap_sdcasr;
	}

	pr_debug("init cpufreq on CPU %d\n", policy->cpu);

	max_freqp = of_get_property(cpu, "clock-frequency", NULL);
	if (!max_freqp) {
		err = -EINVAL;
		goto out_unmap_sdcpwr;
	}

	/* we need the freq in kHz */
	max_freq = *max_freqp / 1000;

	pr_debug("max clock-frequency is at %u kHz\n", max_freq);
	pr_debug("initializing frequency table\n");

	/* initialize frequency table */
	cpufreq_for_each_entry(pos, pas_freqs) {
		pos->frequency = get_astate_freq(pos->driver_data) * 100000;
		pr_debug("%d: %d\n", (int)(pos - pas_freqs), pos->frequency);
	}

	cur_astate = get_cur_astate(policy->cpu);
	pr_debug("current astate is at %d\n",cur_astate);

	policy->cur = pas_freqs[cur_astate].frequency;
	ppc_proc_freq = policy->cur * 1000ul;

	return cpufreq_generic_init(policy, pas_freqs, get_gizmo_latency());

out_unmap_sdcpwr:
	iounmap(sdcpwr_mapbase);

out_unmap_sdcasr:
	iounmap(sdcasr_mapbase);
out:
	return err;
}

static int pas_cpufreq_cpu_exit(struct cpufreq_policy *policy)
{
	/*
	 * We don't support CPU hotplug. Don't unmap after the system
	 * has already made it to a running state.
	 */
	if (system_state >= SYSTEM_RUNNING)
		return 0;

	if (sdcasr_mapbase)
		iounmap(sdcasr_mapbase);
	if (sdcpwr_mapbase)
		iounmap(sdcpwr_mapbase);

	return 0;
}

static int pas_cpufreq_target(struct cpufreq_policy *policy,
			      unsigned int pas_astate_new)
{
	int i;

	pr_debug("setting frequency for cpu %d to %d kHz, 1/%d of max frequency\n",
		 policy->cpu,
		 pas_freqs[pas_astate_new].frequency,
		 pas_freqs[pas_astate_new].driver_data);

	current_astate = pas_astate_new;

	for_each_online_cpu(i)
		set_astate(i, pas_astate_new);

	ppc_proc_freq = pas_freqs[pas_astate_new].frequency * 1000ul;
	return 0;
}

static struct cpufreq_driver pas_cpufreq_driver = {
	.name		= "pas-cpufreq",
	.flags		= CPUFREQ_CONST_LOOPS,
	.init		= pas_cpufreq_cpu_init,
	.exit		= pas_cpufreq_cpu_exit,
	.verify		= cpufreq_generic_frequency_table_verify,
	.target_index	= pas_cpufreq_target,
	.attr		= cpufreq_generic_attr,
};

/*
 * module init and destoy
 */

static int __init pas_cpufreq_init(void)
{
	if (!of_machine_is_compatible("PA6T-1682M") &&
	    !of_machine_is_compatible("pasemi,pwrficient"))
		return -ENODEV;

	return cpufreq_register_driver(&pas_cpufreq_driver);
}

static void __exit pas_cpufreq_exit(void)
{
	cpufreq_unregister_driver(&pas_cpufreq_driver);
}

module_init(pas_cpufreq_init);
module_exit(pas_cpufreq_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>, Olof Johansson <olof@lixom.net>");