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/*
* Copyright (C) STMicroelectronics 2009
* Copyright (C) ST-Ericsson SA 2010
*
* License Terms: GNU General Public License v2
* Author: Sundar Iyer <sundar.iyer@stericsson.com>
*
* CPUIdle driver for U8500
*/
#include <linux/module.h>
#include <linux/hrtimer.h>
#include <linux/sched.h>
#include <linux/clockchips.h>
#include <mach/prcmu-fw-api.h>
#include "cpuidle.h"
struct u8500_cstate u8500_cstates[U8500_NUM_CSTATES] = {
{
.type = U8500_CSTATE_C0,
.sleep_latency = 0,
.wakeup_latency = 0,
.threshold = 0,
.power_usage = -1,
.flags = CPUIDLE_FLAG_SHALLOW | CPUIDLE_FLAG_TIME_VALID,
.desc = "C0 - running",
},
{
.type = U8500_CSTATE_C1,
.sleep_latency = 10,
.wakeup_latency = 10,
.threshold = 10,
.power_usage = 10,
.flags = CPUIDLE_FLAG_SHALLOW | CPUIDLE_FLAG_TIME_VALID,
.desc = "C1 - wait for interrupt",
},
{
.type = U8500_CSTATE_C2,
.sleep_latency = 50,
.wakeup_latency = 50,
.threshold = 20000,
.power_usage = 5,
.flags = CPUIDLE_FLAG_SHALLOW | CPUIDLE_FLAG_TIME_VALID,
.desc = "C2 - WFI-Retention",
},
};
DEFINE_PER_CPU(struct cpuidle_device, u8500_cpuidle_dev);
DEFINE_PER_CPU(int, u8500_cpu_in_wfi) = {0};
struct cpuidle_driver u8500_cpuidle_drv = {
.name = "U8500_CPUIdle",
.owner = THIS_MODULE,
};
static void do_nothing(void *unused)
{
}
/*
* cpu_idle_wait - Used to ensure that all the CPUs discard old value of
* pm_idle and update to new pm_idle value. Required while changing pm_idle
* handler on SMP systems.
*
* Caller must have changed pm_idle to the new value before the call. Old
* pm_idle value will not be used by any CPU after the return of this function.
*/
void cpu_idle_wait(void)
{
smp_mb();
/* kick all the CPUs so that they exit out of pm_idle */
smp_call_function(do_nothing, NULL, 1);
}
EXPORT_SYMBOL_GPL(cpu_idle_wait);
static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *state)
{
ktime_t t1, t2;
s64 diff;
int ret;
t1 = ktime_get();
local_irq_enable();
while (!need_resched())
cpu_relax();
t2 = ktime_get();
diff = ktime_to_us(ktime_sub(t2, t1));
if (diff > INT_MAX)
diff = INT_MAX;
ret = (int)diff;
return ret;
}
static int wfi_idle(struct cpuidle_device *dev, struct cpuidle_state *state)
{
ktime_t t1, t2;
s64 diff;
int ret;
t1 = ktime_get();
__asm__ __volatile__("dsb\n\t" "wfi\n\t" : : : "memory");
t2 = ktime_get();
diff = ktime_to_us(ktime_sub(t2, t1));
if (diff > INT_MAX)
diff = INT_MAX;
ret = (int)diff;
return ret;
}
static int wfi_retention_idle(struct cpuidle_device *dev,
struct cpuidle_state *state)
{
ktime_t t1, t2;
s64 diff;
int ret, cpu, i = 0;
t1 = ktime_get();
per_cpu(u8500_cpu_in_wfi, smp_processor_id()) = 1;
smp_wmb();
cpu = smp_processor_id();
clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
for_each_online_cpu(cpu)
if (per_cpu(u8500_cpu_in_wfi, cpu) == 1)
i++;
if (i == num_online_cpus())
prcmu_apply_ap_state_transition(APEXECUTE_TO_APIDLE,
DDR_PWR_STATE_UNCHANGED, 0);
else {
__asm__ __volatile__("dsb\n\t" "wfi\n\t" : : : "memory");
}
local_irq_disable();
clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
local_irq_enable();
per_cpu(u8500_cpu_in_wfi, smp_processor_id()) = 0;
smp_wmb();
t2 = ktime_get();
diff = ktime_to_us(ktime_sub(t2, t1));
if (diff > INT_MAX)
diff = INT_MAX;
ret = (int)diff;
return ret;
}
static int u8500_enter_idle(struct cpuidle_device *dev,
struct cpuidle_state *state)
{
struct u8500_cstate *cstate;
int ret = 0;
cstate = cpuidle_get_statedata(state);
local_irq_disable();
if (cstate->type == U8500_CSTATE_C1)
ret = wfi_idle(dev, state);
if (cstate->type == U8500_CSTATE_C2)
ret = wfi_retention_idle(dev, state);
if (cstate->type == U8500_CSTATE_C0) {
ret = poll_idle(dev, state);
/* irq already enabled so just return. */
return ret;
}
local_irq_enable();
return ret;
}
static void u8500_cpu_cstate_init(unsigned int cpu)
{
struct cpuidle_device *dev;
struct u8500_cstate *cstate;
struct cpuidle_state *state;
int i;
printk("Initializing CPUIdle for CPU%d...\n", cpu);
dev = &per_cpu(u8500_cpuidle_dev, cpu);
dev->cpu = cpu;
for (i = 0; i < U8500_NUM_CSTATES; i++) {
cstate = &u8500_cstates[i];
state = &dev->states[i];
cpuidle_set_statedata(state, cstate);
state->exit_latency =
cstate->sleep_latency + cstate->wakeup_latency;
state->target_residency = cstate->threshold;
state->flags = cstate->flags;
state->enter = u8500_enter_idle;
state->power_usage = cstate->power_usage;
snprintf(state->name, CPUIDLE_NAME_LEN, "C%d", i);
strncpy(state->desc, cstate->desc, CPUIDLE_DESC_LEN);
}
dev->state_count = U8500_NUM_CSTATES;
if (dev->state_count >= 2)
dev->safe_state = &dev->states[1];
else
dev->safe_state = &dev->states[0];
if (cpuidle_register_device(dev)) {
printk(KERN_ERR "%s: CPUidle register device failed\n",
__func__);
}
}
static int __init u8500_cpuidle_init(void)
{
int result = 0;
unsigned int cpu;
result = cpuidle_register_driver(&u8500_cpuidle_drv);
if (result < 0)
goto out;
/* TODO: pass a per-cpu var to get the return value of
cpuidle_register_device */
/* on_each_cpu(u8500_cpu_cstate_init, NULL, 0); */
for_each_online_cpu(cpu)
u8500_cpu_cstate_init(cpu);
out:
return result;
}
static void __exit u8500_cpuidle_exit(void)
{
/* TODO: disable cpuidle devices & unregister driver */
}
module_init(u8500_cpuidle_init);
module_exit(u8500_cpuidle_exit);
MODULE_DESCRIPTION("U8500 CPUIdle driver");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("STMicroelectronics/Sundar Iyer, ST-Ericsson");
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