95 lines
2.6 KiB
C
95 lines
2.6 KiB
C
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/*
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* based on arch/arm/mach-kirkwood/cpuidle.c
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*
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* CPU idle support for AT91 SoC
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*
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* This file is licensed under the terms of the GNU General Public
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* License version 2. This program is licensed "as is" without any
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* warranty of any kind, whether express or implied.
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*
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* The cpu idle uses wait-for-interrupt and RAM self refresh in order
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* to implement two idle states -
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* #1 wait-for-interrupt
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* #2 wait-for-interrupt and RAM self refresh
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/platform_device.h>
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#include <linux/cpuidle.h>
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#include <asm/proc-fns.h>
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#include <linux/io.h>
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#include "pm.h"
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#define AT91_MAX_STATES 2
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static DEFINE_PER_CPU(struct cpuidle_device, at91_cpuidle_device);
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static struct cpuidle_driver at91_idle_driver = {
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.name = "at91_idle",
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.owner = THIS_MODULE,
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};
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/* Actual code that puts the SoC in different idle states */
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static int at91_enter_idle(struct cpuidle_device *dev,
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struct cpuidle_state *state)
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{
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struct timeval before, after;
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int idle_time;
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u32 saved_lpr;
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local_irq_disable();
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do_gettimeofday(&before);
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if (state == &dev->states[0])
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/* Wait for interrupt state */
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cpu_do_idle();
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else if (state == &dev->states[1]) {
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asm("b 1f; .align 5; 1:");
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asm("mcr p15, 0, r0, c7, c10, 4"); /* drain write buffer */
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saved_lpr = sdram_selfrefresh_enable();
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cpu_do_idle();
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sdram_selfrefresh_disable(saved_lpr);
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}
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do_gettimeofday(&after);
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local_irq_enable();
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idle_time = (after.tv_sec - before.tv_sec) * USEC_PER_SEC +
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(after.tv_usec - before.tv_usec);
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return idle_time;
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}
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/* Initialize CPU idle by registering the idle states */
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static int at91_init_cpuidle(void)
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{
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struct cpuidle_device *device;
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cpuidle_register_driver(&at91_idle_driver);
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device = &per_cpu(at91_cpuidle_device, smp_processor_id());
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device->state_count = AT91_MAX_STATES;
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/* Wait for interrupt state */
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device->states[0].enter = at91_enter_idle;
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device->states[0].exit_latency = 1;
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device->states[0].target_residency = 10000;
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device->states[0].flags = CPUIDLE_FLAG_TIME_VALID;
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strcpy(device->states[0].name, "WFI");
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strcpy(device->states[0].desc, "Wait for interrupt");
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/* Wait for interrupt and RAM self refresh state */
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device->states[1].enter = at91_enter_idle;
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device->states[1].exit_latency = 10;
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device->states[1].target_residency = 10000;
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device->states[1].flags = CPUIDLE_FLAG_TIME_VALID;
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strcpy(device->states[1].name, "RAM_SR");
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strcpy(device->states[1].desc, "WFI and RAM Self Refresh");
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if (cpuidle_register_device(device)) {
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printk(KERN_ERR "at91_init_cpuidle: Failed registering\n");
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return -EIO;
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}
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return 0;
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}
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device_initcall(at91_init_cpuidle);
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