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authorAlbin Tonnerre <albin.tonnerre@free-electrons.com>2009-11-01 18:40:50 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2009-11-10 23:46:35 +0000
commit1ea60cf7062271f0d53d09268726aa1544bf4836 (patch)
tree4e975655fa555fd2346ec50112fbbc8244cb03da /arch/arm/mach-at91/cpuidle.c
parentcd3abf98aeaec9b23a926159856b54a95707ee88 (diff)
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 <nicolas.ferre@atmel.com> Signed-off-by: Albin Tonnerre <albin.tonnerre@free-electrons.com> Acked-by: Andrew Victor <linux@maxim.org.za> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/mach-at91/cpuidle.c')
-rw-r--r--arch/arm/mach-at91/cpuidle.c94
1 files changed, 94 insertions, 0 deletions
diff --git a/arch/arm/mach-at91/cpuidle.c b/arch/arm/mach-at91/cpuidle.c
new file mode 100644
index 000000000000..1cfeac1483d6
--- /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 <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/cpuidle.h>
+#include <asm/proc-fns.h>
+#include <linux/io.h>
+
+#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);