/*
   * Cpufreq driver for the loongson-2 processors
   *
   * The 2E revision of loongson processor not support this feature.
   *
   * Copyright (C) 2006 - 2008 Lemote Inc. & Insititute of Computing Technology
   * Author: Yanhua, yanh@lemote.com
   *
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   */
  #include <linux/cpufreq.h>
  #include <linux/module.h>
  #include <linux/err.h>
  #include <linux/sched.h>	/* set_cpus_allowed() */
  #include <linux/delay.h>
  #include <linux/platform_device.h>
  
  #include <asm/clock.h>
  #include <asm/idle.h>
  
  #include <asm/mach-loongson/loongson.h>
  
  static uint nowait;
  
  static void (*saved_cpu_wait) (void);
  
  static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
  					unsigned long val, void *data);
  
  static struct notifier_block loongson2_cpufreq_notifier_block = {
  	.notifier_call = loongson2_cpu_freq_notifier
  };
  
  static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
  					unsigned long val, void *data)
  {
  	if (val == CPUFREQ_POSTCHANGE)
  		current_cpu_data.udelay_val = loops_per_jiffy;
  
  	return 0;
  }
  
  /*
   * Here we notify other drivers of the proposed change and the final change.
   */
  static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
  				     unsigned int index)
  {
  	unsigned int cpu = policy->cpu;
  	cpumask_t cpus_allowed;
  	unsigned int freq;
  
  	cpus_allowed = current->cpus_allowed;
  	set_cpus_allowed_ptr(current, cpumask_of(cpu));
  
  	freq =
  	    ((cpu_clock_freq / 1000) *
  	     loongson2_clockmod_table[index].driver_data) / 8;
  
  	set_cpus_allowed_ptr(current, &cpus_allowed);
  
  	/* setting the cpu frequency */
  	clk_set_rate(policy->clk, freq * 1000);
  
  	return 0;
  }
  
  static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
  {
  	struct clk *cpuclk;
  	int i;
  	unsigned long rate;
  	int ret;
  
  	cpuclk = clk_get(NULL, "cpu_clk");
  	if (IS_ERR(cpuclk)) {
  		printk(KERN_ERR "cpufreq: couldn't get CPU clk
  ");
  		return PTR_ERR(cpuclk);
  	}
  
  	rate = cpu_clock_freq / 1000;
  	if (!rate) {
  		clk_put(cpuclk);
  		return -EINVAL;
  	}
  
  	/* clock table init */
  	for (i = 2;
  	     (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
  	     i++)
  		loongson2_clockmod_table[i].frequency = (rate * i) / 8;
  
  	ret = clk_set_rate(cpuclk, rate * 1000);
  	if (ret) {
  		clk_put(cpuclk);
  		return ret;
  	}
  
  	policy->clk = cpuclk;
  	return cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
  }
  
  static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
  {
  	cpufreq_frequency_table_put_attr(policy->cpu);
  	clk_put(policy->clk);
  	return 0;
  }
  
  static struct cpufreq_driver loongson2_cpufreq_driver = {
  	.name = "loongson2",
  	.init = loongson2_cpufreq_cpu_init,
  	.verify = cpufreq_generic_frequency_table_verify,
  	.target_index = loongson2_cpufreq_target,
  	.get = cpufreq_generic_get,
  	.exit = loongson2_cpufreq_exit,
  	.attr = cpufreq_generic_attr,
  };
  
  static struct platform_device_id platform_device_ids[] = {
  	{
  		.name = "loongson2_cpufreq",
  	},
  	{}
  };
  
  MODULE_DEVICE_TABLE(platform, platform_device_ids);
  
  static struct platform_driver platform_driver = {
  	.driver = {
  		.name = "loongson2_cpufreq",
  		.owner = THIS_MODULE,
  	},
  	.id_table = platform_device_ids,
  };
  
  /*
   * This is the simple version of Loongson-2 wait, Maybe we need do this in
   * interrupt disabled context.
   */
  
  static DEFINE_SPINLOCK(loongson2_wait_lock);
  
  static void loongson2_cpu_wait(void)
  {
  	unsigned long flags;
  	u32 cpu_freq;
  
  	spin_lock_irqsave(&loongson2_wait_lock, flags);
  	cpu_freq = LOONGSON_CHIPCFG0;
  	LOONGSON_CHIPCFG0 &= ~0x7;	/* Put CPU into wait mode */
  	LOONGSON_CHIPCFG0 = cpu_freq;	/* Restore CPU state */
  	spin_unlock_irqrestore(&loongson2_wait_lock, flags);
  	local_irq_enable();
  }
  
  static int __init cpufreq_init(void)
  {
  	int ret;
  
  	/* Register platform stuff */
  	ret = platform_driver_register(&platform_driver);
  	if (ret)
  		return ret;
  
  	pr_info("cpufreq: Loongson-2F CPU frequency driver.
  ");
  
  	cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
  				  CPUFREQ_TRANSITION_NOTIFIER);
  
  	ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
  
  	if (!ret && !nowait) {
  		saved_cpu_wait = cpu_wait;
  		cpu_wait = loongson2_cpu_wait;
  	}
  
  	return ret;
  }
  
  static void __exit cpufreq_exit(void)
  {
  	if (!nowait && saved_cpu_wait)
  		cpu_wait = saved_cpu_wait;
  	cpufreq_unregister_driver(&loongson2_cpufreq_driver);
  	cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
  				    CPUFREQ_TRANSITION_NOTIFIER);
  
  	platform_driver_unregister(&platform_driver);
  }
  
  module_init(cpufreq_init);
  module_exit(cpufreq_exit);
  
  module_param(nowait, uint, 0644);
  MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
  
  MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
  MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
  MODULE_LICENSE("GPL");