/*
* 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[] = {
{ 0, SOURCE_HCLK, FREQ_DVS },
{ 0, SOURCE_ARMDIV, 133333 },
{ 0, SOURCE_ARMDIV, 266666 },
{ 0, SOURCE_ARMDIV, 400000 },
{ 0, 0, CPUFREQ_TABLE_END },
};
static struct cpufreq_frequency_table s3c2450_freq_table[] = {
{ 0, SOURCE_HCLK, FREQ_DVS },
{ 0, SOURCE_ARMDIV, 133500 },
{ 0, SOURCE_ARMDIV, 267000 },
{ 0, SOURCE_ARMDIV, 534000 },
{ 0, 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 *pos;
struct s3c2416_dvfs *dvfs;
count = regulator_count_voltages(s3c_freq->vddarm);
if (count < 0) {
pr_err("cpufreq: Unable to check supported voltages\n");
return;
}
if (!count)
goto out;
cpufreq_for_each_valid_entry(pos, s3c_freq->freq_table) {
dvfs = &s3c2416_dvfs_table[pos->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",
pos->frequency);
pos->frequency = CPUFREQ_ENTRY_INVALID;
}
}
out:
/* 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 *pos;
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
cpufreq_for_each_entry(pos, s3c_freq->freq_table) {
/* special handling for dvs mode */
if (pos->driver_data == 0) {
if (!s3c_freq->hclk) {
pr_debug("cpufreq: %dkHz unsupported as it would need unavailable dvs mode\n",
pos->frequency);
pos->frequency = CPUFREQ_ENTRY_INVALID;
} else {
continue;
}
}
/* Check for frequencies we can generate */
rate = clk_round_rate(s3c_freq->armdiv,
pos->frequency * 1000);
rate /= 1000;
if (rate != pos->frequency) {
pr_debug("cpufreq: %dkHz unsupported by clock (clk_round_rate return %lu)\n",
pos->frequency, rate);
pos->frequency = CPUFREQ_ENTRY_INVALID;
}
}
/* 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);
