drivers/cpufreq/s3c2416-cpufreq.c - arm/linux-arm-legacy - Git at Google

 /*
  * S3C2416/2450 CPUfreq Support
  *
  * Copyright 2011 Heiko Stuebner <heiko@sntech.de>
  *
  * based on s3c64xx_cpufreq.c
  *
  * Copyright 2009 Wolfson Microelectronics plc
  *
  * 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/kernel.h>
 #include <linux/types.h>
 #include <linux/init.h>
 #include <linux/cpufreq.h>
 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/regulator/consumer.h>
 #include <linux/reboot.h>
 #include <linux/module.h>

 static DEFINE_MUTEX(cpufreq_lock);

 struct s3c2416_data {
 	struct clk *armdiv;
 	struct clk *armclk;
 	struct clk *hclk;

 	unsigned long regulator_latency;
 #ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
 	struct regulator *vddarm;
 #endif

 	struct cpufreq_frequency_table *freq_table;

 	bool is_dvs;
 	bool disable_dvs;
 };

 static struct s3c2416_data s3c2416_cpufreq;

 struct s3c2416_dvfs {
 	unsigned int vddarm_min;
 	unsigned int vddarm_max;
 };

 /* pseudo-frequency for dvs mode */
 #define FREQ_DVS	132333

 /* frequency to sleep and reboot in
  * it's essential to leave dvs, as some boards do not reconfigure the
  * regulator on reboot
  */
 #define FREQ_SLEEP	133333

 /* Sources for the ARMCLK */
 #define SOURCE_HCLK	0
 #define SOURCE_ARMDIV	1

 #ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
 /* S3C2416 only supports changing the voltage in the dvs-mode.
  * Voltages down to 1.0V seem to work, so we take what the regulator
  * can get us.
  */
 static struct s3c2416_dvfs s3c2416_dvfs_table[] = {
 	[SOURCE_HCLK] = {  950000, 1250000 },
 	[SOURCE_ARMDIV] = { 1250000, 1350000 },
 };
 #endif

 static struct cpufreq_frequency_table s3c2416_freq_table[] = {
 	{ SOURCE_HCLK, FREQ_DVS },
 	{ SOURCE_ARMDIV, 133333 },
 	{ SOURCE_ARMDIV, 266666 },
 	{ SOURCE_ARMDIV, 400000 },
 	{ 0, CPUFREQ_TABLE_END },
 };

 static struct cpufreq_frequency_table s3c2450_freq_table[] = {
 	{ SOURCE_HCLK, FREQ_DVS },
 	{ SOURCE_ARMDIV, 133500 },
 	{ SOURCE_ARMDIV, 267000 },
 	{ SOURCE_ARMDIV, 534000 },
 	{ 0, CPUFREQ_TABLE_END },
 };

 static unsigned int s3c2416_cpufreq_get_speed(unsigned int cpu)
 {
 	struct s3c2416_data *s3c_freq = &s3c2416_cpufreq;

 	if (cpu != 0)
 		return 0;

 	/* return our pseudo-frequency when in dvs mode */
 	if (s3c_freq->is_dvs)
 		return FREQ_DVS;

 	return clk_get_rate(s3c_freq->armclk) / 1000;
 }

 static int s3c2416_cpufreq_set_armdiv(struct s3c2416_data *s3c_freq,
 				      unsigned int freq)
 {
 	int ret;

 	if (clk_get_rate(s3c_freq->armdiv) / 1000 != freq) {
 		ret = clk_set_rate(s3c_freq->armdiv, freq * 1000);
 		if (ret < 0) {
 			pr_err("cpufreq: Failed to set armdiv rate %dkHz: %d\n",
 			       freq, ret);
 			return ret;
 		}
 	}

 	return 0;
 }

 static int s3c2416_cpufreq_enter_dvs(struct s3c2416_data *s3c_freq, int idx)
 {
 #ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
 	struct s3c2416_dvfs *dvfs;
 #endif
 	int ret;

 	if (s3c_freq->is_dvs) {
 		pr_debug("cpufreq: already in dvs mode, nothing to do\n");
 		return 0;
 	}

 	pr_debug("cpufreq: switching armclk to hclk (%lukHz)\n",
 		 clk_get_rate(s3c_freq->hclk) / 1000);
 	ret = clk_set_parent(s3c_freq->armclk, s3c_freq->hclk);
 	if (ret < 0) {
 		pr_err("cpufreq: Failed to switch armclk to hclk: %d\n", ret);
 		return ret;
 	}

 #ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
 	/* changing the core voltage is only allowed when in dvs mode */
 	if (s3c_freq->vddarm) {
 		dvfs = &s3c2416_dvfs_table[idx];

 		pr_debug("cpufreq: setting regulator to %d-%d\n",
 			 dvfs->vddarm_min, dvfs->vddarm_max);
 		ret = regulator_set_voltage(s3c_freq->vddarm,
 					    dvfs->vddarm_min,
 					    dvfs->vddarm_max);

 		/* when lowering the voltage failed, there is nothing to do */
 		if (ret != 0)
 			pr_err("cpufreq: Failed to set VDDARM: %d\n", ret);
 	}
 #endif

 	s3c_freq->is_dvs = 1;

 	return 0;
 }

 static int s3c2416_cpufreq_leave_dvs(struct s3c2416_data *s3c_freq, int idx)
 {
 #ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
 	struct s3c2416_dvfs *dvfs;
 #endif
 	int ret;

 	if (!s3c_freq->is_dvs) {
 		pr_debug("cpufreq: not in dvs mode, so can't leave\n");
 		return 0;
 	}

 #ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
 	if (s3c_freq->vddarm) {
 		dvfs = &s3c2416_dvfs_table[idx];

 		pr_debug("cpufreq: setting regulator to %d-%d\n",
 			 dvfs->vddarm_min, dvfs->vddarm_max);
 		ret = regulator_set_voltage(s3c_freq->vddarm,
 					    dvfs->vddarm_min,
 					    dvfs->vddarm_max);
 		if (ret != 0) {
 			pr_err("cpufreq: Failed to set VDDARM: %d\n", ret);
 			return ret;
 		}
 	}
 #endif

 	/* force armdiv to hclk frequency for transition from dvs*/
 	if (clk_get_rate(s3c_freq->armdiv) > clk_get_rate(s3c_freq->hclk)) {
 		pr_debug("cpufreq: force armdiv to hclk frequency (%lukHz)\n",
 			 clk_get_rate(s3c_freq->hclk) / 1000);
 		ret = s3c2416_cpufreq_set_armdiv(s3c_freq,
 					clk_get_rate(s3c_freq->hclk) / 1000);
 		if (ret < 0) {
 			pr_err("cpufreq: Failed to set the armdiv to %lukHz: %d\n",
 			       clk_get_rate(s3c_freq->hclk) / 1000, ret);
 			return ret;
 		}
 	}

 	pr_debug("cpufreq: switching armclk parent to armdiv (%lukHz)\n",
 			clk_get_rate(s3c_freq->armdiv) / 1000);

 	ret = clk_set_parent(s3c_freq->armclk, s3c_freq->armdiv);
 	if (ret < 0) {
 		pr_err("cpufreq: Failed to switch armclk clock parent to armdiv: %d\n",
 		       ret);
 		return ret;
 	}

 	s3c_freq->is_dvs = 0;

 	return 0;
 }

 static int s3c2416_cpufreq_set_target(struct cpufreq_policy *policy,
 				      unsigned int index)
 {
 	struct s3c2416_data *s3c_freq = &s3c2416_cpufreq;
 	unsigned int new_freq;
 	int idx, ret, to_dvs = 0;

 	mutex_lock(&cpufreq_lock);

 	idx = s3c_freq->freq_table[index].driver_data;

 	if (idx == SOURCE_HCLK)
 		to_dvs = 1;

 	/* switching to dvs when it's not allowed */
 	if (to_dvs && s3c_freq->disable_dvs) {
 		pr_debug("cpufreq: entering dvs mode not allowed\n");
 		ret = -EINVAL;
 		goto out;
 	}

 	/* When leavin dvs mode, always switch the armdiv to the hclk rate
 	 * The S3C2416 has stability issues when switching directly to
 	 * higher frequencies.
 	 */
 	new_freq = (s3c_freq->is_dvs && !to_dvs)
 				? clk_get_rate(s3c_freq->hclk) / 1000
 				: s3c_freq->freq_table[index].frequency;

 	if (to_dvs) {
 		pr_debug("cpufreq: enter dvs\n");
 		ret = s3c2416_cpufreq_enter_dvs(s3c_freq, idx);
 	} else if (s3c_freq->is_dvs) {
 		pr_debug("cpufreq: leave dvs\n");
 		ret = s3c2416_cpufreq_leave_dvs(s3c_freq, idx);
 	} else {
 		pr_debug("cpufreq: change armdiv to %dkHz\n", new_freq);
 		ret = s3c2416_cpufreq_set_armdiv(s3c_freq, new_freq);
 	}

 out:
 	mutex_unlock(&cpufreq_lock);

 	return ret;
 }

 #ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
 static void __init s3c2416_cpufreq_cfg_regulator(struct s3c2416_data *s3c_freq)
 {
 	int count, v, i, found;
 	struct cpufreq_frequency_table *freq;
 	struct s3c2416_dvfs *dvfs;

 	count = regulator_count_voltages(s3c_freq->vddarm);
 	if (count < 0) {
 		pr_err("cpufreq: Unable to check supported voltages\n");
 		return;
 	}

 	freq = s3c_freq->freq_table;
 	while (count > 0 && freq->frequency != CPUFREQ_TABLE_END) {
 		if (freq->frequency == CPUFREQ_ENTRY_INVALID)
 			continue;

 		dvfs = &s3c2416_dvfs_table[freq->driver_data];
 		found = 0;

 		/* Check only the min-voltage, more is always ok on S3C2416 */
 		for (i = 0; i < count; i++) {
 			v = regulator_list_voltage(s3c_freq->vddarm, i);
 			if (v >= dvfs->vddarm_min)
 				found = 1;
 		}

 		if (!found) {
 			pr_debug("cpufreq: %dkHz unsupported by regulator\n",
 				 freq->frequency);
 			freq->frequency = CPUFREQ_ENTRY_INVALID;
 		}

 		freq++;
 	}

 	/* Guessed */
 	s3c_freq->regulator_latency = 1 * 1000 * 1000;
 }
 #endif

 static int s3c2416_cpufreq_reboot_notifier_evt(struct notifier_block *this,
 					       unsigned long event, void *ptr)
 {
 	struct s3c2416_data *s3c_freq = &s3c2416_cpufreq;
 	int ret;

 	mutex_lock(&cpufreq_lock);

 	/* disable further changes */
 	s3c_freq->disable_dvs = 1;

 	mutex_unlock(&cpufreq_lock);

 	/* some boards don't reconfigure the regulator on reboot, which
 	 * could lead to undervolting the cpu when the clock is reset.
 	 * Therefore we always leave the DVS mode on reboot.
 	 */
 	if (s3c_freq->is_dvs) {
 		pr_debug("cpufreq: leave dvs on reboot\n");
 		ret = cpufreq_driver_target(cpufreq_cpu_get(0), FREQ_SLEEP, 0);
 		if (ret < 0)
 			return NOTIFY_BAD;
 	}

 	return NOTIFY_DONE;
 }

 static struct notifier_block s3c2416_cpufreq_reboot_notifier = {
 	.notifier_call = s3c2416_cpufreq_reboot_notifier_evt,
 };

 static int __init s3c2416_cpufreq_driver_init(struct cpufreq_policy *policy)
 {
 	struct s3c2416_data *s3c_freq = &s3c2416_cpufreq;
 	struct cpufreq_frequency_table *freq;
 	struct clk *msysclk;
 	unsigned long rate;
 	int ret;

 	if (policy->cpu != 0)
 		return -EINVAL;

 	msysclk = clk_get(NULL, "msysclk");
 	if (IS_ERR(msysclk)) {
 		ret = PTR_ERR(msysclk);
 		pr_err("cpufreq: Unable to obtain msysclk: %d\n", ret);
 		return ret;
 	}

 	/*
 	 * S3C2416 and S3C2450 share the same processor-ID and also provide no
 	 * other means to distinguish them other than through the rate of
 	 * msysclk. On S3C2416 msysclk runs at 800MHz and on S3C2450 at 533MHz.
 	 */
 	rate = clk_get_rate(msysclk);
 	if (rate == 800 * 1000 * 1000) {
 		pr_info("cpufreq: msysclk running at %lukHz, using S3C2416 frequency table\n",
 			rate / 1000);
 		s3c_freq->freq_table = s3c2416_freq_table;
 		policy->cpuinfo.max_freq = 400000;
 	} else if (rate / 1000 == 534000) {
 		pr_info("cpufreq: msysclk running at %lukHz, using S3C2450 frequency table\n",
 			rate / 1000);
 		s3c_freq->freq_table = s3c2450_freq_table;
 		policy->cpuinfo.max_freq = 534000;
 	}

 	/* not needed anymore */
 	clk_put(msysclk);

 	if (s3c_freq->freq_table == NULL) {
 		pr_err("cpufreq: No frequency information for this CPU, msysclk at %lukHz\n",
 		       rate / 1000);
 		return -ENODEV;
 	}

 	s3c_freq->is_dvs = 0;

 	s3c_freq->armdiv = clk_get(NULL, "armdiv");
 	if (IS_ERR(s3c_freq->armdiv)) {
 		ret = PTR_ERR(s3c_freq->armdiv);
 		pr_err("cpufreq: Unable to obtain ARMDIV: %d\n", ret);
 		return ret;
 	}

 	s3c_freq->hclk = clk_get(NULL, "hclk");
 	if (IS_ERR(s3c_freq->hclk)) {
 		ret = PTR_ERR(s3c_freq->hclk);
 		pr_err("cpufreq: Unable to obtain HCLK: %d\n", ret);
 		goto err_hclk;
 	}

 	/* chech hclk rate, we only support the common 133MHz for now
 	 * hclk could also run at 66MHz, but this not often used
 	 */
 	rate = clk_get_rate(s3c_freq->hclk);
 	if (rate < 133 * 1000 * 1000) {
 		pr_err("cpufreq: HCLK not at 133MHz\n");
 		clk_put(s3c_freq->hclk);
 		ret = -EINVAL;
 		goto err_armclk;
 	}

 	s3c_freq->armclk = clk_get(NULL, "armclk");
 	if (IS_ERR(s3c_freq->armclk)) {
 		ret = PTR_ERR(s3c_freq->armclk);
 		pr_err("cpufreq: Unable to obtain ARMCLK: %d\n", ret);
 		goto err_armclk;
 	}

 #ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
 	s3c_freq->vddarm = regulator_get(NULL, "vddarm");
 	if (IS_ERR(s3c_freq->vddarm)) {
 		ret = PTR_ERR(s3c_freq->vddarm);
 		pr_err("cpufreq: Failed to obtain VDDARM: %d\n", ret);
 		goto err_vddarm;
 	}

 	s3c2416_cpufreq_cfg_regulator(s3c_freq);
 #else
 	s3c_freq->regulator_latency = 0;
 #endif

 	freq = s3c_freq->freq_table;
 	while (freq->frequency != CPUFREQ_TABLE_END) {
 		/* special handling for dvs mode */
 		if (freq->driver_data == 0) {
 			if (!s3c_freq->hclk) {
 				pr_debug("cpufreq: %dkHz unsupported as it would need unavailable dvs mode\n",
 					 freq->frequency);
 				freq->frequency = CPUFREQ_ENTRY_INVALID;
 			} else {
 				freq++;
 				continue;
 			}
 		}

 		/* Check for frequencies we can generate */
 		rate = clk_round_rate(s3c_freq->armdiv,
 				      freq->frequency * 1000);
 		rate /= 1000;
 		if (rate != freq->frequency) {
 			pr_debug("cpufreq: %dkHz unsupported by clock (clk_round_rate return %lu)\n",
 				 freq->frequency, rate);
 			freq->frequency = CPUFREQ_ENTRY_INVALID;
 		}

 		freq++;
 	}

 	/* Datasheet says PLL stabalisation time must be at least 300us,
 	 * so but add some fudge. (reference in LOCKCON0 register description)
 	 */
 	ret = cpufreq_generic_init(policy, s3c_freq->freq_table,
 			(500 * 1000) + s3c_freq->regulator_latency);
 	if (ret)
 		goto err_freq_table;

 	register_reboot_notifier(&s3c2416_cpufreq_reboot_notifier);

 	return 0;

 err_freq_table:
 #ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
 	regulator_put(s3c_freq->vddarm);
 err_vddarm:
 #endif
 	clk_put(s3c_freq->armclk);
 err_armclk:
 	clk_put(s3c_freq->hclk);
 err_hclk:
 	clk_put(s3c_freq->armdiv);

 	return ret;
 }

 static struct cpufreq_driver s3c2416_cpufreq_driver = {
 	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 	.verify		= cpufreq_generic_frequency_table_verify,
 	.target_index	= s3c2416_cpufreq_set_target,
 	.get		= s3c2416_cpufreq_get_speed,
 	.init		= s3c2416_cpufreq_driver_init,
 	.name		= "s3c2416",
 	.attr		= cpufreq_generic_attr,
 };

 static int __init s3c2416_cpufreq_init(void)
 {
 	return cpufreq_register_driver(&s3c2416_cpufreq_driver);
 }
 module_init(s3c2416_cpufreq_init);
	/*
	* S3C2416/2450 CPUfreq Support
	*
	* Copyright 2011 Heiko Stuebner <heiko@sntech.de>
	*
	* based on s3c64xx_cpufreq.c
	*
	* Copyright 2009 Wolfson Microelectronics plc
	*
	* 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/kernel.h>
	#include <linux/types.h>
	#include <linux/init.h>
	#include <linux/cpufreq.h>
	#include <linux/clk.h>
	#include <linux/err.h>
	#include <linux/regulator/consumer.h>
	#include <linux/reboot.h>
	#include <linux/module.h>

	static DEFINE_MUTEX(cpufreq_lock);

	struct s3c2416_data {
	struct clk *armdiv;
	struct clk *armclk;
	struct clk *hclk;

	unsigned long regulator_latency;
	#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
	struct regulator *vddarm;
	#endif

	struct cpufreq_frequency_table *freq_table;

	bool is_dvs;
	bool disable_dvs;
	};

	static struct s3c2416_data s3c2416_cpufreq;

	struct s3c2416_dvfs {
	unsigned int vddarm_min;
	unsigned int vddarm_max;
	};

	/* pseudo-frequency for dvs mode */
	#define FREQ_DVS 132333

	/* frequency to sleep and reboot in
	* it's essential to leave dvs, as some boards do not reconfigure the
	* regulator on reboot
	*/
	#define FREQ_SLEEP 133333

	/* Sources for the ARMCLK */
	#define SOURCE_HCLK 0
	#define SOURCE_ARMDIV 1

	#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
	/* S3C2416 only supports changing the voltage in the dvs-mode.
	* Voltages down to 1.0V seem to work, so we take what the regulator
	* can get us.
	*/
	static struct s3c2416_dvfs s3c2416_dvfs_table[] = {
	[SOURCE_HCLK] = { 950000, 1250000 },
	[SOURCE_ARMDIV] = { 1250000, 1350000 },
	};
	#endif

	static struct cpufreq_frequency_table s3c2416_freq_table[] = {
	{ SOURCE_HCLK, FREQ_DVS },
	{ SOURCE_ARMDIV, 133333 },
	{ SOURCE_ARMDIV, 266666 },
	{ SOURCE_ARMDIV, 400000 },
	{ 0, CPUFREQ_TABLE_END },
	};

	static struct cpufreq_frequency_table s3c2450_freq_table[] = {
	{ SOURCE_HCLK, FREQ_DVS },
	{ SOURCE_ARMDIV, 133500 },
	{ SOURCE_ARMDIV, 267000 },
	{ SOURCE_ARMDIV, 534000 },
	{ 0, CPUFREQ_TABLE_END },
	};

	static unsigned int s3c2416_cpufreq_get_speed(unsigned int cpu)
	{
	struct s3c2416_data *s3c_freq = &s3c2416_cpufreq;

	if (cpu != 0)
	return 0;

	/* return our pseudo-frequency when in dvs mode */
	if (s3c_freq->is_dvs)
	return FREQ_DVS;

	return clk_get_rate(s3c_freq->armclk) / 1000;
	}

	static int s3c2416_cpufreq_set_armdiv(struct s3c2416_data *s3c_freq,
	unsigned int freq)
	{
	int ret;

	if (clk_get_rate(s3c_freq->armdiv) / 1000 != freq) {
	ret = clk_set_rate(s3c_freq->armdiv, freq * 1000);
	if (ret < 0) {
	pr_err("cpufreq: Failed to set armdiv rate %dkHz: %d\n",
	freq, ret);
	return ret;
	}
	}

	return 0;
	}

	static int s3c2416_cpufreq_enter_dvs(struct s3c2416_data *s3c_freq, int idx)
	{
	#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
	struct s3c2416_dvfs *dvfs;
	#endif
	int ret;

	if (s3c_freq->is_dvs) {
	pr_debug("cpufreq: already in dvs mode, nothing to do\n");
	return 0;
	}

	pr_debug("cpufreq: switching armclk to hclk (%lukHz)\n",
	clk_get_rate(s3c_freq->hclk) / 1000);
	ret = clk_set_parent(s3c_freq->armclk, s3c_freq->hclk);
	if (ret < 0) {
	pr_err("cpufreq: Failed to switch armclk to hclk: %d\n", ret);
	return ret;
	}

	#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
	/* changing the core voltage is only allowed when in dvs mode */
	if (s3c_freq->vddarm) {
	dvfs = &s3c2416_dvfs_table[idx];

	pr_debug("cpufreq: setting regulator to %d-%d\n",
	dvfs->vddarm_min, dvfs->vddarm_max);
	ret = regulator_set_voltage(s3c_freq->vddarm,
	dvfs->vddarm_min,
	dvfs->vddarm_max);

	/* when lowering the voltage failed, there is nothing to do */
	if (ret != 0)
	pr_err("cpufreq: Failed to set VDDARM: %d\n", ret);
	}
	#endif

	s3c_freq->is_dvs = 1;

	return 0;
	}

	static int s3c2416_cpufreq_leave_dvs(struct s3c2416_data *s3c_freq, int idx)
	{
	#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
	struct s3c2416_dvfs *dvfs;
	#endif
	int ret;

	if (!s3c_freq->is_dvs) {
	pr_debug("cpufreq: not in dvs mode, so can't leave\n");
	return 0;
	}

	#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
	if (s3c_freq->vddarm) {
	dvfs = &s3c2416_dvfs_table[idx];

	pr_debug("cpufreq: setting regulator to %d-%d\n",
	dvfs->vddarm_min, dvfs->vddarm_max);
	ret = regulator_set_voltage(s3c_freq->vddarm,
	dvfs->vddarm_min,
	dvfs->vddarm_max);
	if (ret != 0) {
	pr_err("cpufreq: Failed to set VDDARM: %d\n", ret);
	return ret;
	}
	}
	#endif

	/* force armdiv to hclk frequency for transition from dvs*/
	if (clk_get_rate(s3c_freq->armdiv) > clk_get_rate(s3c_freq->hclk)) {
	pr_debug("cpufreq: force armdiv to hclk frequency (%lukHz)\n",
	clk_get_rate(s3c_freq->hclk) / 1000);
	ret = s3c2416_cpufreq_set_armdiv(s3c_freq,
	clk_get_rate(s3c_freq->hclk) / 1000);
	if (ret < 0) {
	pr_err("cpufreq: Failed to set the armdiv to %lukHz: %d\n",
	clk_get_rate(s3c_freq->hclk) / 1000, ret);
	return ret;
	}
	}

	pr_debug("cpufreq: switching armclk parent to armdiv (%lukHz)\n",
	clk_get_rate(s3c_freq->armdiv) / 1000);

	ret = clk_set_parent(s3c_freq->armclk, s3c_freq->armdiv);
	if (ret < 0) {
	pr_err("cpufreq: Failed to switch armclk clock parent to armdiv: %d\n",
	ret);
	return ret;
	}

	s3c_freq->is_dvs = 0;

	return 0;
	}

	static int s3c2416_cpufreq_set_target(struct cpufreq_policy *policy,
	unsigned int index)
	{
	struct s3c2416_data *s3c_freq = &s3c2416_cpufreq;
	unsigned int new_freq;
	int idx, ret, to_dvs = 0;

	mutex_lock(&cpufreq_lock);

	idx = s3c_freq->freq_table[index].driver_data;

	if (idx == SOURCE_HCLK)
	to_dvs = 1;

	/* switching to dvs when it's not allowed */
	if (to_dvs && s3c_freq->disable_dvs) {
	pr_debug("cpufreq: entering dvs mode not allowed\n");
	ret = -EINVAL;
	goto out;
	}

	/* When leavin dvs mode, always switch the armdiv to the hclk rate
	* The S3C2416 has stability issues when switching directly to
	* higher frequencies.
	*/
	new_freq = (s3c_freq->is_dvs && !to_dvs)
	? clk_get_rate(s3c_freq->hclk) / 1000
	: s3c_freq->freq_table[index].frequency;

	if (to_dvs) {
	pr_debug("cpufreq: enter dvs\n");
	ret = s3c2416_cpufreq_enter_dvs(s3c_freq, idx);
	} else if (s3c_freq->is_dvs) {
	pr_debug("cpufreq: leave dvs\n");
	ret = s3c2416_cpufreq_leave_dvs(s3c_freq, idx);
	} else {
	pr_debug("cpufreq: change armdiv to %dkHz\n", new_freq);
	ret = s3c2416_cpufreq_set_armdiv(s3c_freq, new_freq);
	}

	out:
	mutex_unlock(&cpufreq_lock);

	return ret;
	}

	#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
	static void __init s3c2416_cpufreq_cfg_regulator(struct s3c2416_data *s3c_freq)
	{
	int count, v, i, found;
	struct cpufreq_frequency_table *freq;
	struct s3c2416_dvfs *dvfs;

	count = regulator_count_voltages(s3c_freq->vddarm);
	if (count < 0) {
	pr_err("cpufreq: Unable to check supported voltages\n");
	return;
	}

	freq = s3c_freq->freq_table;
	while (count > 0 && freq->frequency != CPUFREQ_TABLE_END) {
	if (freq->frequency == CPUFREQ_ENTRY_INVALID)
	continue;

	dvfs = &s3c2416_dvfs_table[freq->driver_data];
	found = 0;

	/* Check only the min-voltage, more is always ok on S3C2416 */
	for (i = 0; i < count; i++) {
	v = regulator_list_voltage(s3c_freq->vddarm, i);
	if (v >= dvfs->vddarm_min)
	found = 1;
	}

	if (!found) {
	pr_debug("cpufreq: %dkHz unsupported by regulator\n",
	freq->frequency);
	freq->frequency = CPUFREQ_ENTRY_INVALID;
	}

	freq++;
	}

	/* Guessed */
	s3c_freq->regulator_latency = 1 * 1000 * 1000;
	}
	#endif

	static int s3c2416_cpufreq_reboot_notifier_evt(struct notifier_block *this,
	unsigned long event, void *ptr)
	{
	struct s3c2416_data *s3c_freq = &s3c2416_cpufreq;
	int ret;

	mutex_lock(&cpufreq_lock);

	/* disable further changes */
	s3c_freq->disable_dvs = 1;

	mutex_unlock(&cpufreq_lock);

	/* some boards don't reconfigure the regulator on reboot, which
	* could lead to undervolting the cpu when the clock is reset.
	* Therefore we always leave the DVS mode on reboot.
	*/
	if (s3c_freq->is_dvs) {
	pr_debug("cpufreq: leave dvs on reboot\n");
	ret = cpufreq_driver_target(cpufreq_cpu_get(0), FREQ_SLEEP, 0);
	if (ret < 0)
	return NOTIFY_BAD;
	}

	return NOTIFY_DONE;
	}

	static struct notifier_block s3c2416_cpufreq_reboot_notifier = {
	.notifier_call = s3c2416_cpufreq_reboot_notifier_evt,
	};

	static int __init s3c2416_cpufreq_driver_init(struct cpufreq_policy *policy)
	{
	struct s3c2416_data *s3c_freq = &s3c2416_cpufreq;
	struct cpufreq_frequency_table *freq;
	struct clk *msysclk;
	unsigned long rate;
	int ret;

	if (policy->cpu != 0)
	return -EINVAL;

	msysclk = clk_get(NULL, "msysclk");
	if (IS_ERR(msysclk)) {
	ret = PTR_ERR(msysclk);
	pr_err("cpufreq: Unable to obtain msysclk: %d\n", ret);
	return ret;
	}

	/*
	* S3C2416 and S3C2450 share the same processor-ID and also provide no
	* other means to distinguish them other than through the rate of
	* msysclk. On S3C2416 msysclk runs at 800MHz and on S3C2450 at 533MHz.
	*/
	rate = clk_get_rate(msysclk);
	if (rate == 800 * 1000 * 1000) {
	pr_info("cpufreq: msysclk running at %lukHz, using S3C2416 frequency table\n",
	rate / 1000);
	s3c_freq->freq_table = s3c2416_freq_table;
	policy->cpuinfo.max_freq = 400000;
	} else if (rate / 1000 == 534000) {
	pr_info("cpufreq: msysclk running at %lukHz, using S3C2450 frequency table\n",
	rate / 1000);
	s3c_freq->freq_table = s3c2450_freq_table;
	policy->cpuinfo.max_freq = 534000;
	}

	/* not needed anymore */
	clk_put(msysclk);

	if (s3c_freq->freq_table == NULL) {
	pr_err("cpufreq: No frequency information for this CPU, msysclk at %lukHz\n",
	rate / 1000);
	return -ENODEV;
	}

	s3c_freq->is_dvs = 0;

	s3c_freq->armdiv = clk_get(NULL, "armdiv");
	if (IS_ERR(s3c_freq->armdiv)) {
	ret = PTR_ERR(s3c_freq->armdiv);
	pr_err("cpufreq: Unable to obtain ARMDIV: %d\n", ret);
	return ret;
	}

	s3c_freq->hclk = clk_get(NULL, "hclk");
	if (IS_ERR(s3c_freq->hclk)) {
	ret = PTR_ERR(s3c_freq->hclk);
	pr_err("cpufreq: Unable to obtain HCLK: %d\n", ret);
	goto err_hclk;
	}

	/* chech hclk rate, we only support the common 133MHz for now
	* hclk could also run at 66MHz, but this not often used
	*/
	rate = clk_get_rate(s3c_freq->hclk);
	if (rate < 133 * 1000 * 1000) {
	pr_err("cpufreq: HCLK not at 133MHz\n");
	clk_put(s3c_freq->hclk);
	ret = -EINVAL;
	goto err_armclk;
	}

	s3c_freq->armclk = clk_get(NULL, "armclk");
	if (IS_ERR(s3c_freq->armclk)) {
	ret = PTR_ERR(s3c_freq->armclk);
	pr_err("cpufreq: Unable to obtain ARMCLK: %d\n", ret);
	goto err_armclk;
	}

	#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
	s3c_freq->vddarm = regulator_get(NULL, "vddarm");
	if (IS_ERR(s3c_freq->vddarm)) {
	ret = PTR_ERR(s3c_freq->vddarm);
	pr_err("cpufreq: Failed to obtain VDDARM: %d\n", ret);
	goto err_vddarm;
	}

	s3c2416_cpufreq_cfg_regulator(s3c_freq);
	#else
	s3c_freq->regulator_latency = 0;
	#endif

	freq = s3c_freq->freq_table;
	while (freq->frequency != CPUFREQ_TABLE_END) {
	/* special handling for dvs mode */
	if (freq->driver_data == 0) {
	if (!s3c_freq->hclk) {
	pr_debug("cpufreq: %dkHz unsupported as it would need unavailable dvs mode\n",
	freq->frequency);
	freq->frequency = CPUFREQ_ENTRY_INVALID;
	} else {
	freq++;
	continue;
	}
	}

	/* Check for frequencies we can generate */
	rate = clk_round_rate(s3c_freq->armdiv,
	freq->frequency * 1000);
	rate /= 1000;
	if (rate != freq->frequency) {
	pr_debug("cpufreq: %dkHz unsupported by clock (clk_round_rate return %lu)\n",
	freq->frequency, rate);
	freq->frequency = CPUFREQ_ENTRY_INVALID;
	}

	freq++;
	}

	/* Datasheet says PLL stabalisation time must be at least 300us,
	* so but add some fudge. (reference in LOCKCON0 register description)
	*/
	ret = cpufreq_generic_init(policy, s3c_freq->freq_table,
	(500 * 1000) + s3c_freq->regulator_latency);
	if (ret)
	goto err_freq_table;

	register_reboot_notifier(&s3c2416_cpufreq_reboot_notifier);

	return 0;

	err_freq_table:
	#ifdef CONFIG_ARM_S3C2416_CPUFREQ_VCORESCALE
	regulator_put(s3c_freq->vddarm);
	err_vddarm:
	#endif
	clk_put(s3c_freq->armclk);
	err_armclk:
	clk_put(s3c_freq->hclk);
	err_hclk:
	clk_put(s3c_freq->armdiv);

	return ret;
	}

	static struct cpufreq_driver s3c2416_cpufreq_driver = {
	.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
	.verify = cpufreq_generic_frequency_table_verify,
	.target_index = s3c2416_cpufreq_set_target,
	.get = s3c2416_cpufreq_get_speed,
	.init = s3c2416_cpufreq_driver_init,
	.name = "s3c2416",
	.attr = cpufreq_generic_attr,
	};

	static int __init s3c2416_cpufreq_init(void)
	{
	return cpufreq_register_driver(&s3c2416_cpufreq_driver);
	}
	module_init(s3c2416_cpufreq_init);