[ARM] Kirkwood: CPU idle driver

The patch adds support for Kirkwood cpu idle.
Two idle states are defined:
1. Wait-for-interrupt (replacing default kirkwood wfi)
2. Wait-for-interrupt and DDR self refresh

Signed-off-by: Rabeeh Khoury <rabeeh@marvell.com>
Signed-off-by: Nicolas Pitre <nico@marvell.com>

1 files changed, 96 insertions, 0 deletions

diff --git a/arch/arm/mach-kirkwood/cpuidle.c b/arch/arm/mach-kirkwood/cpuidle.c
new file mode 100644
index 000000000000..f68d33f1f396
--- /dev/null
+++ b/arch/arm/mach-kirkwood/cpuidle.c
@@ -0,0 +1,96 @@
+/*
+ * arch/arm/mach-kirkwood/cpuidle.c
+ *
+ * CPU idle Marvell Kirkwood SoCs
+ *
+ * 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 DDR self refresh in order
+ * to implement two idle states -
+ * #1 wait-for-interrupt
+ * #2 wait-for-interrupt and DDR self refresh
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/cpuidle.h>
+#include <linux/io.h>
+#include <asm/proc-fns.h>
+#include <mach/kirkwood.h>
+
+#define KIRKWOOD_MAX_STATES     2
+
+static struct cpuidle_driver kirkwood_idle_driver = {
+        .name =         "kirkwood_idle",
+        .owner =        THIS_MODULE,
+};
+
+static DEFINE_PER_CPU(struct cpuidle_device, kirkwood_cpuidle_device);
+
+/* Actual code that puts the SoC in different idle states */
+static int kirkwood_enter_idle(struct cpuidle_device *dev,
+                               struct cpuidle_state *state)
+{
+        struct timeval before, after;
+        int idle_time;
+
+        local_irq_disable();
+        do_gettimeofday(&before);
+        if (state == &dev->states[0])
+                /* Wait for interrupt state */
+                cpu_do_idle();
+        else if (state == &dev->states[1]) {
+                /*
+                 * Following write will put DDR in self refresh.
+                 * Note that we have 256 cycles before DDR puts it
+                 * self in self-refresh, so the wait-for-interrupt
+                 * call afterwards won't get the DDR from self refresh
+                 * mode.
+                 */
+                writel(0x7, DDR_OPERATION_BASE);
+                cpu_do_idle();
+        }
+        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 kirkwood_init_cpuidle(void)
+{
+        struct cpuidle_device *device;
+
+        cpuidle_register_driver(&kirkwood_idle_driver);
+
+        device = &per_cpu(kirkwood_cpuidle_device, smp_processor_id());
+        device->state_count = KIRKWOOD_MAX_STATES;
+
+        /* Wait for interrupt state */
+        device->states[0].enter = kirkwood_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 DDR self refresh state */
+        device->states[1].enter = kirkwood_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, "DDR SR");
+        strcpy(device->states[1].desc, "WFI and DDR Self Refresh");
+
+        if (cpuidle_register_device(device)) {
+                printk(KERN_ERR "kirkwood_init_cpuidle: Failed registering\n");
+                return -EIO;
+        }
+        return 0;
+}
+
+device_initcall(kirkwood_init_cpuidle);