sh: cpuidle for SuperH Mobile using hwblk

This patch adds cpuidle support for SuperH Mobile.

The sleep mode selected by cpuidle is compared with
the mode selected by the hwblk sleep code and the
best allowed mode is entered.

At this point "Sleep mode" and "Sleep mode + SF" are
supported. This code can easily be extended to support
"Software suspend mode", but the assembly code must
first be updated to avoid loosing interrupts.

Also, update the code to only copy the assembly snippet
into internal memory once at bootup.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

4 files changed, 125 insertions, 13 deletions

diff --git a/arch/sh/include/asm/suspend.h b/arch/sh/include/asm/suspend.h
index b1b995370e7..5c8ea28ff7a 100644
--- a/arch/sh/include/asm/suspend.h
+++ b/arch/sh/include/asm/suspend.h
@@ -10,6 +10,15 @@ struct swsusp_arch_regs {
 	struct pt_regs user_regs;
 	unsigned long bank1_regs[8];
 };
+
+void sh_mobile_call_standby(unsigned long mode);
+
+#ifdef CONFIG_CPU_IDLE
+void sh_mobile_setup_cpuidle(void);
+#else
+static inline void sh_mobile_setup_cpuidle(void) {}
+#endif
+
 #endif
 
 /* flags passed to assembly suspend code */
diff --git a/arch/sh/kernel/cpu/shmobile/Makefile b/arch/sh/kernel/cpu/shmobile/Makefile
index 08bfa7c7db2..e8a5111e848 100644
--- a/arch/sh/kernel/cpu/shmobile/Makefile
+++ b/arch/sh/kernel/cpu/shmobile/Makefile
@@ -4,3 +4,4 @@
 
 # Power Management & Sleep mode
 obj-$(CONFIG_PM)	+= pm.o sleep.o
+obj-$(CONFIG_CPU_IDLE)	+= cpuidle.o
diff --git a/arch/sh/kernel/cpu/shmobile/cpuidle.c b/arch/sh/kernel/cpu/shmobile/cpuidle.c
new file mode 100644
index 00000000000..4afdd975cc6
--- /dev/null
+++ b/arch/sh/kernel/cpu/shmobile/cpuidle.c
@@ -0,0 +1,102 @@
+/*
+ * arch/sh/kernel/cpu/shmobile/cpuidle.c
+ *
+ * Cpuidle support code for SuperH Mobile
+ *
+ *  Copyright (C) 2009 Magnus Damm
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/io.h>
+#include <linux/suspend.h>
+#include <linux/cpuidle.h>
+#include <asm/suspend.h>
+#include <asm/uaccess.h>
+#include <asm/hwblk.h>
+
+static unsigned long cpuidle_mode[] = {
+	SUSP_SH_SLEEP, /* regular sleep mode */
+	SUSP_SH_SLEEP | SUSP_SH_SF, /* sleep mode + self refresh */
+};
+
+static int cpuidle_sleep_enter(struct cpuidle_device *dev,
+			       struct cpuidle_state *state)
+{
+	unsigned long allowed_mode = arch_hwblk_sleep_mode();
+	ktime_t before, after;
+	int requested_state = state - &dev->states[0];
+	int allowed_state;
+	int k;
+
+	/* convert allowed mode to allowed state */
+	for (k = ARRAY_SIZE(cpuidle_mode) - 1; k > 0; k--)
+		if (cpuidle_mode[k] == allowed_mode)
+			break;
+
+	allowed_state = k;
+
+	/* take the following into account for sleep mode selection:
+	 * - allowed_state: best mode allowed by hardware (clock deps)
+	 * - requested_state: best mode allowed by software (latencies)
+	 */
+	k = min_t(int, allowed_state, requested_state);
+
+	dev->last_state = &dev->states[k];
+	before = ktime_get();
+	sh_mobile_call_standby(cpuidle_mode[k]);
+	after = ktime_get();
+	return ktime_to_ns(ktime_sub(after, before)) >> 10;
+}
+
+static struct cpuidle_device cpuidle_dev;
+static struct cpuidle_driver cpuidle_driver = {
+	.name =		"sh_idle",
+	.owner =	THIS_MODULE,
+};
+
+void sh_mobile_setup_cpuidle(void)
+{
+	struct cpuidle_device *dev = &cpuidle_dev;
+	struct cpuidle_state *state;
+	int i;
+
+	cpuidle_register_driver(&cpuidle_driver);
+
+	for (i = 0; i < CPUIDLE_STATE_MAX; i++) {
+		dev->states[i].name[0] = '\0';
+		dev->states[i].desc[0] = '\0';
+	}
+
+	i = CPUIDLE_DRIVER_STATE_START;
+
+	state = &dev->states[i++];
+	snprintf(state->name, CPUIDLE_NAME_LEN, "C0");
+	strncpy(state->desc, "SuperH Sleep Mode", CPUIDLE_DESC_LEN);
+	state->exit_latency = 1;
+	state->target_residency = 1 * 2;
+	state->power_usage = 3;
+	state->flags = 0;
+	state->flags |= CPUIDLE_FLAG_SHALLOW;
+	state->flags |= CPUIDLE_FLAG_TIME_VALID;
+	state->enter = cpuidle_sleep_enter;
+
+	dev->safe_state = state;
+
+	state = &dev->states[i++];
+	snprintf(state->name, CPUIDLE_NAME_LEN, "C1");
+	strncpy(state->desc, "SuperH Sleep Mode [SF]", CPUIDLE_DESC_LEN);
+	state->exit_latency = 100;
+	state->target_residency = 1 * 2;
+	state->power_usage = 1;
+	state->flags = 0;
+	state->flags |= CPUIDLE_FLAG_TIME_VALID;
+	state->enter = cpuidle_sleep_enter;
+
+	dev->state_count = i;
+
+	cpuidle_register_device(dev);
+}
diff --git a/arch/sh/kernel/cpu/shmobile/pm.c b/arch/sh/kernel/cpu/shmobile/pm.c
index 8c067adf683..de078d24ce5 100644
--- a/arch/sh/kernel/cpu/shmobile/pm.c
+++ b/arch/sh/kernel/cpu/shmobile/pm.c
@@ -1,5 +1,5 @@
 /*
- * arch/sh/kernel/cpu/sh4a/pm-sh_mobile.c
+ * arch/sh/kernel/cpu/shmobile/pm.c
  *
  * Power management support code for SuperH Mobile
  *
@@ -32,20 +32,17 @@
  *
  * R-standby mode is unsupported, but will be added in the future
  * U-standby mode is low priority since it needs bootloader hacks
- *
- * All modes should be tied in with cpuidle. But before that can
- * happen we need to keep track of enabled hardware blocks so we
- * can avoid entering sleep modes that stop clocks to hardware
- * blocks that are in use even though the cpu core is idle.
  */
 
+#define ILRAM_BASE 0xe5200000
+
 extern const unsigned char sh_mobile_standby[];
 extern const unsigned int sh_mobile_standby_size;
 
-static void sh_mobile_call_standby(unsigned long mode)
+void sh_mobile_call_standby(unsigned long mode)
 {
 	extern void *vbr_base;
-	void *onchip_mem = (void *)0xe5200000; /* ILRAM */
+	void *onchip_mem = (void *)ILRAM_BASE;
 	void (*standby_onchip_mem)(unsigned long) = onchip_mem;
 
 	/* Note: Wake up from sleep may generate exceptions!
@@ -55,11 +52,6 @@ static void sh_mobile_call_standby(unsigned long mode)
 	if (mode & SUSP_SH_SF)
 		asm volatile("ldc %0, vbr" : : "r" (onchip_mem) : "memory");
 
-	/* Copy the assembly snippet to the otherwise ununsed ILRAM */
-	memcpy(onchip_mem, sh_mobile_standby, sh_mobile_standby_size);
-	wmb();
-	ctrl_barrier();
-
 	/* Let assembly snippet in on-chip memory handle the rest */
 	standby_onchip_mem(mode);
 
@@ -85,7 +77,15 @@ static struct platform_suspend_ops sh_pm_ops = {
 
 static int __init sh_pm_init(void)
 {
+	void *onchip_mem = (void *)ILRAM_BASE;
+
+	/* Copy the assembly snippet to the otherwise ununsed ILRAM */
+	memcpy(onchip_mem, sh_mobile_standby, sh_mobile_standby_size);
+	wmb();
+	ctrl_barrier();
+
 	suspend_set_ops(&sh_pm_ops);
+	sh_mobile_setup_cpuidle();
 	return 0;
 }