/*
   * 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
  ", 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
  ", max_freq);

  	pr_debug("initializing frequency table
  ");
  
  	/* initialize frequency table */

  	cpufreq_for_each_entry(pos, pas_freqs) {
  		pos->frequency = get_astate_freq(pos->driver_data) * 100000;
  		pr_debug("%d: %d
  ", (int)(pos - pas_freqs), pos->frequency);

  	}

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