cpuidle.c
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/*
* CPU idle for DaVinci SoCs
*
* Copyright (C) 2009 Texas Instruments Incorporated. http://www.ti.com/
*
* Derived from Marvell Kirkwood CPU idle code
* (arch/arm/mach-kirkwood/cpuidle.c)
*
* 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/init.h>
#include <linux/platform_device.h>
#include <linux/cpuidle.h>
#include <linux/io.h>
#include <linux/export.h>
#include <asm/proc-fns.h>
#include <mach/cpuidle.h>
#include <mach/ddr2.h>
#define DAVINCI_CPUIDLE_MAX_STATES 2
struct davinci_ops {
void (*enter) (u32 flags);
void (*exit) (u32 flags);
u32 flags;
};
/* fields in davinci_ops.flags */
#define DAVINCI_CPUIDLE_FLAGS_DDR2_PWDN BIT(0)
static struct cpuidle_driver davinci_idle_driver = {
.name = "cpuidle-davinci",
.owner = THIS_MODULE,
};
static DEFINE_PER_CPU(struct cpuidle_device, davinci_cpuidle_device);
static void __iomem *ddr2_reg_base;
static void davinci_save_ddr_power(int enter, bool pdown)
{
u32 val;
val = __raw_readl(ddr2_reg_base + DDR2_SDRCR_OFFSET);
if (enter) {
if (pdown)
val |= DDR2_SRPD_BIT;
else
val &= ~DDR2_SRPD_BIT;
val |= DDR2_LPMODEN_BIT;
} else {
val &= ~(DDR2_SRPD_BIT | DDR2_LPMODEN_BIT);
}
__raw_writel(val, ddr2_reg_base + DDR2_SDRCR_OFFSET);
}
static void davinci_c2state_enter(u32 flags)
{
davinci_save_ddr_power(1, !!(flags & DAVINCI_CPUIDLE_FLAGS_DDR2_PWDN));
}
static void davinci_c2state_exit(u32 flags)
{
davinci_save_ddr_power(0, !!(flags & DAVINCI_CPUIDLE_FLAGS_DDR2_PWDN));
}
static struct davinci_ops davinci_states[DAVINCI_CPUIDLE_MAX_STATES] = {
[1] = {
.enter = davinci_c2state_enter,
.exit = davinci_c2state_exit,
},
};
/* Actual code that puts the SoC in different idle states */
static int davinci_enter_idle(struct cpuidle_device *dev,
struct cpuidle_driver *drv,
int index)
{
struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
struct davinci_ops *ops = cpuidle_get_statedata(state_usage);
struct timeval before, after;
int idle_time;
local_irq_disable();
do_gettimeofday(&before);
if (ops && ops->enter)
ops->enter(ops->flags);
/* Wait for interrupt state */
cpu_do_idle();
if (ops && ops->exit)
ops->exit(ops->flags);
do_gettimeofday(&after);
local_irq_enable();
idle_time = (after.tv_sec - before.tv_sec) * USEC_PER_SEC +
(after.tv_usec - before.tv_usec);
dev->last_residency = idle_time;
return index;
}
static int __init davinci_cpuidle_probe(struct platform_device *pdev)
{
int ret;
struct cpuidle_device *device;
struct cpuidle_driver *driver = &davinci_idle_driver;
struct davinci_cpuidle_config *pdata = pdev->dev.platform_data;
device = &per_cpu(davinci_cpuidle_device, smp_processor_id());
if (!pdata) {
dev_err(&pdev->dev, "cannot get platform data\n");
return -ENOENT;
}
ddr2_reg_base = pdata->ddr2_ctlr_base;
/* Wait for interrupt state */
driver->states[0].enter = davinci_enter_idle;
driver->states[0].exit_latency = 1;
driver->states[0].target_residency = 10000;
driver->states[0].flags = CPUIDLE_FLAG_TIME_VALID;
strcpy(driver->states[0].name, "WFI");
strcpy(driver->states[0].desc, "Wait for interrupt");
/* Wait for interrupt and DDR self refresh state */
driver->states[1].enter = davinci_enter_idle;
driver->states[1].exit_latency = 10;
driver->states[1].target_residency = 10000;
driver->states[1].flags = CPUIDLE_FLAG_TIME_VALID;
strcpy(driver->states[1].name, "DDR SR");
strcpy(driver->states[1].desc, "WFI and DDR Self Refresh");
if (pdata->ddr2_pdown)
davinci_states[1].flags |= DAVINCI_CPUIDLE_FLAGS_DDR2_PWDN;
cpuidle_set_statedata(&device->states_usage[1], &davinci_states[1]);
device->state_count = DAVINCI_CPUIDLE_MAX_STATES;
driver->state_count = DAVINCI_CPUIDLE_MAX_STATES;
ret = cpuidle_register_driver(&davinci_idle_driver);
if (ret) {
dev_err(&pdev->dev, "failed to register driver\n");
return ret;
}
ret = cpuidle_register_device(device);
if (ret) {
dev_err(&pdev->dev, "failed to register device\n");
cpuidle_unregister_driver(&davinci_idle_driver);
return ret;
}
return 0;
}
static struct platform_driver davinci_cpuidle_driver = {
.driver = {
.name = "cpuidle-davinci",
.owner = THIS_MODULE,
},
};
static int __init davinci_cpuidle_init(void)
{
return platform_driver_probe(&davinci_cpuidle_driver,
davinci_cpuidle_probe);
}
device_initcall(davinci_cpuidle_init);