From 1ea60cf7062271f0d53d09268726aa1544bf4836 Mon Sep 17 00:00:00 2001 From: Albin Tonnerre Date: Sun, 1 Nov 2009 18:40:50 +0100 Subject: ARM: 5778/1: AT91: Add cpuidle support This patch adds the support for cpuidle on AT91 SoCs, taken from the cpuidle support in mach-kirkwood. cpuidle needs sdram_selfrefresh_enable and _disable, so move their definition to a separate header file instead of duplicating the code already used in pm.c. Tested-by: Nicolas Ferre Signed-off-by: Albin Tonnerre Acked-by: Andrew Victor Signed-off-by: Russell King --- arch/arm/mach-at91/cpuidle.c | 94 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 94 insertions(+) create mode 100644 arch/arm/mach-at91/cpuidle.c (limited to 'arch/arm/mach-at91/cpuidle.c') diff --git a/arch/arm/mach-at91/cpuidle.c b/arch/arm/mach-at91/cpuidle.c new file mode 100644 index 00000000000..1cfeac1483d --- /dev/null +++ b/arch/arm/mach-at91/cpuidle.c @@ -0,0 +1,94 @@ +/* + * based on arch/arm/mach-kirkwood/cpuidle.c + * + * CPU idle support for AT91 SoC + * + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + * + * The cpu idle uses wait-for-interrupt and RAM self refresh in order + * to implement two idle states - + * #1 wait-for-interrupt + * #2 wait-for-interrupt and RAM self refresh + */ + +#include +#include +#include +#include +#include +#include + +#include "pm.h" + +#define AT91_MAX_STATES 2 + +static DEFINE_PER_CPU(struct cpuidle_device, at91_cpuidle_device); + +static struct cpuidle_driver at91_idle_driver = { + .name = "at91_idle", + .owner = THIS_MODULE, +}; + +/* Actual code that puts the SoC in different idle states */ +static int at91_enter_idle(struct cpuidle_device *dev, + struct cpuidle_state *state) +{ + struct timeval before, after; + int idle_time; + u32 saved_lpr; + + local_irq_disable(); + do_gettimeofday(&before); + if (state == &dev->states[0]) + /* Wait for interrupt state */ + cpu_do_idle(); + else if (state == &dev->states[1]) { + asm("b 1f; .align 5; 1:"); + asm("mcr p15, 0, r0, c7, c10, 4"); /* drain write buffer */ + saved_lpr = sdram_selfrefresh_enable(); + cpu_do_idle(); + sdram_selfrefresh_disable(saved_lpr); + } + do_gettimeofday(&after); + local_irq_enable(); + idle_time = (after.tv_sec - before.tv_sec) * USEC_PER_SEC + + (after.tv_usec - before.tv_usec); + return idle_time; +} + +/* Initialize CPU idle by registering the idle states */ +static int at91_init_cpuidle(void) +{ + struct cpuidle_device *device; + + cpuidle_register_driver(&at91_idle_driver); + + device = &per_cpu(at91_cpuidle_device, smp_processor_id()); + device->state_count = AT91_MAX_STATES; + + /* Wait for interrupt state */ + device->states[0].enter = at91_enter_idle; + device->states[0].exit_latency = 1; + device->states[0].target_residency = 10000; + device->states[0].flags = CPUIDLE_FLAG_TIME_VALID; + strcpy(device->states[0].name, "WFI"); + strcpy(device->states[0].desc, "Wait for interrupt"); + + /* Wait for interrupt and RAM self refresh state */ + device->states[1].enter = at91_enter_idle; + device->states[1].exit_latency = 10; + device->states[1].target_residency = 10000; + device->states[1].flags = CPUIDLE_FLAG_TIME_VALID; + strcpy(device->states[1].name, "RAM_SR"); + strcpy(device->states[1].desc, "WFI and RAM Self Refresh"); + + if (cpuidle_register_device(device)) { + printk(KERN_ERR "at91_init_cpuidle: Failed registering\n"); + return -EIO; + } + return 0; +} + +device_initcall(at91_init_cpuidle); -- cgit v1.2.3-70-g09d2