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linux/drivers/cpufreq/s3c2416-cpufreq.c
Viresh Kumar ae6b427132 cpufreq: Mark ARM drivers with CPUFREQ_NEED_INITIAL_FREQ_CHECK flag 
Sometimes boot loaders set CPU frequency to a value outside of frequency table
present with cpufreq core. In such cases CPU might be unstable if it has to run
on that frequency for long duration of time and so its better to set it to a
frequency which is specified in frequency table.

On some systems we can't really say what frequency we're running at the moment
and so for these we shouldn't check if we are running at a frequency present in
frequency table. And so we really can't force this for all the cpufreq drivers.

Hence we are created another flag here: CPUFREQ_NEED_INITIAL_FREQ_CHECK that
will be marked by platforms which want to go for this check at boot time.

Initially this is done for all ARM platforms but others may follow if required.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-01-06 14:17:25 +01:00

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/*
* 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);
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