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/*
* cpufreq driver for the cell processor
*
* (C) Copyright IBM Deutschland Entwicklung GmbH 2005
*
* Author: Christian Krafft <krafft@de.ibm.com>
*
* 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 <asm/hw_irq.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/prom.h>
#include <asm/time.h>
#include "cbe_regs.h"
static DEFINE_MUTEX(cbe_switch_mutex);
/* the CBE supports an 8 step frequency scaling */
static struct cpufreq_frequency_table cbe_freqs[] = {
{1, 0},
{2, 0},
{3, 0},
{4, 0},
{5, 0},
{6, 0},
{8, 0},
{10, 0},
{0, CPUFREQ_TABLE_END},
};
/* to write to MIC register */
static u64 MIC_Slow_Fast_Timer_table[] = {
[0 ... 7] = 0x007fc00000000000ull,
};
/* more values for the MIC */
static u64 MIC_Slow_Next_Timer_table[] = {
0x0000240000000000ull,
0x0000268000000000ull,
0x000029C000000000ull,
0x00002D0000000000ull,
0x0000300000000000ull,
0x0000334000000000ull,
0x000039C000000000ull,
0x00003FC000000000ull,
};
/*
* hardware specific functions
*/
static int get_pmode(int cpu)
{
int ret;
struct cbe_pmd_regs __iomem *pmd_regs;
pmd_regs = cbe_get_cpu_pmd_regs(cpu);
ret = in_be64(&pmd_regs->pmsr) & 0x07;
return ret;
}
static int set_pmode(int cpu, unsigned int pmode)
{
struct cbe_pmd_regs __iomem *pmd_regs;
struct cbe_mic_tm_regs __iomem *mic_tm_regs;
u64 flags;
u64 value;
local_irq_save(flags);
mic_tm_regs = cbe_get_cpu_mic_tm_regs(cpu);
pmd_regs = cbe_get_cpu_pmd_regs(cpu);
pr_debug("pm register is mapped at %p\n", &pmd_regs->pmcr);
pr_debug("mic register is mapped at %p\n", &mic_tm_regs->slow_fast_timer_0);
out_be64(&mic_tm_regs->slow_fast_timer_0, MIC_Slow_Fast_Timer_table[pmode]);
out_be64(&mic_tm_regs->slow_fast_timer_1, MIC_Slow_Fast_Timer_table[pmode]);
out_be64(&mic_tm_regs->slow_next_timer_0, MIC_Slow_Next_Timer_table[pmode]);
out_be64(&mic_tm_regs->slow_next_timer_1, MIC_Slow_Next_Timer_table[pmode]);
value = in_be64(&pmd_regs->pmcr);
/* set bits to zero */
value &= 0xFFFFFFFFFFFFFFF8ull;
/* set bits to next pmode */
value |= pmode;
out_be64(&pmd_regs->pmcr, value);
/* wait until new pmode appears in status register */
value = in_be64(&pmd_regs->pmsr) & 0x07;
while(value != pmode) {
cpu_relax();
value = in_be64(&pmd_regs->pmsr) & 0x07;
}
local_irq_restore(flags);
return 0;
}
/*
* cpufreq functions
*/
static int cbe_cpufreq_cpu_init (struct cpufreq_policy *policy)
{
u32 *max_freq;
int i, cur_pmode;
struct device_node *cpu;
cpu = of_get_cpu_node(policy->cpu, NULL);
if(!cpu)
return -ENODEV;
pr_debug("init cpufreq on CPU %d\n", policy->cpu);
max_freq = (u32*) get_property(cpu, "clock-frequency", NULL);
if(!max_freq)
return -EINVAL;
// we need the freq in kHz
*max_freq /= 1000;
pr_debug("max clock-frequency is at %u kHz\n", *max_freq);
pr_debug("initializing frequency table\n");
// initialize frequency table
for (i=0; cbe_freqs[i].frequency!=CPUFREQ_TABLE_END; i++) {
cbe_freqs[i].frequency = *max_freq / cbe_freqs[i].index;
pr_debug("%d: %d\n", i, cbe_freqs[i].frequency);
}
policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
/* if DEBUG is enabled set_pmode() measures the correct latency of a transition */
policy->cpuinfo.transition_latency = 25000;
cur_pmode = get_pmode(policy->cpu);
pr_debug("current pmode is at %d\n",cur_pmode);
policy->cur = cbe_freqs[cur_pmode].frequency;
#ifdef CONFIG_SMP
policy->cpus = cpu_sibling_map[policy->cpu];
#endif
cpufreq_frequency_table_get_attr (cbe_freqs, policy->cpu);
/* this ensures that policy->cpuinfo_min and policy->cpuinfo_max are set correctly */
return cpufreq_frequency_table_cpuinfo (policy, cbe_freqs);
}
static int cbe_cpufreq_cpu_exit(struct cpufreq_policy *policy)
{
cpufreq_frequency_table_put_attr(policy->cpu);
return 0;
}
static int cbe_cpufreq_verify(struct cpufreq_policy *policy)
{
return cpufreq_frequency_table_verify(policy, cbe_freqs);
}
static int cbe_cpufreq_target(struct cpufreq_policy *policy, unsigned int target_freq,
unsigned int relation)
{
int rc;
struct cpufreq_freqs freqs;
int cbe_pmode_new;
cpufreq_frequency_table_target(policy,
cbe_freqs,
target_freq,
relation,
&cbe_pmode_new);
freqs.old = policy->cur;
freqs.new = cbe_freqs[cbe_pmode_new].frequency;
freqs.cpu = policy->cpu;
mutex_lock (&cbe_switch_mutex);
cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
pr_debug("setting frequency for cpu %d to %d kHz, 1/%d of max frequency\n",
policy->cpu,
cbe_freqs[cbe_pmode_new].frequency,
cbe_freqs[cbe_pmode_new].index);
rc = set_pmode(policy->cpu, cbe_pmode_new);
cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
mutex_unlock(&cbe_switch_mutex);
return rc;
}
static struct cpufreq_driver cbe_cpufreq_driver = {
.verify = cbe_cpufreq_verify,
.target = cbe_cpufreq_target,
.init = cbe_cpufreq_cpu_init,
.exit = cbe_cpufreq_cpu_exit,
.name = "cbe-cpufreq",
.owner = THIS_MODULE,
.flags = CPUFREQ_CONST_LOOPS,
};
/*
* module init and destoy
*/
static int __init cbe_cpufreq_init(void)
{
return cpufreq_register_driver(&cbe_cpufreq_driver);
}
static void __exit cbe_cpufreq_exit(void)
{
cpufreq_unregister_driver(&cbe_cpufreq_driver);
}
module_init(cbe_cpufreq_init);
module_exit(cbe_cpufreq_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");
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