cpuidle: add Calxeda SOC idle support

Add support for core powergating on Calxeda platforms. Initially, this
supports ECX-1000 (highbank), but support will be added for ECX-2000
later.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: Len Brown <len.brown@intel.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>

3 files changed, 173 insertions, 0 deletions

diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
index a76b689e553b..d2d007b0651a 100644
--- a/drivers/cpuidle/Kconfig
+++ b/drivers/cpuidle/Kconfig
@@ -21,3 +21,13 @@ config CPU_IDLE_GOV_MENU
 
 config ARCH_NEEDS_CPU_IDLE_COUPLED
         def_bool n
+
+if CPU_IDLE
+
+config CPU_IDLE_CALXEDA
+        bool "CPU Idle Driver for Calxeda processors"
+        depends on ARCH_HIGHBANK
+        help
+          Select this to enable cpuidle on Calxeda processors.
+
+endif
diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
index 38c8f69f30cf..03ee87482c71 100644
--- a/drivers/cpuidle/Makefile
+++ b/drivers/cpuidle/Makefile
@@ -4,3 +4,5 @@
 
 obj-y += cpuidle.o driver.o governor.o sysfs.o governors/
 obj-$(CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED) += coupled.o
+
+obj-$(CONFIG_CPU_IDLE_CALXEDA) += cpuidle-calxeda.o
diff --git a/drivers/cpuidle/cpuidle-calxeda.c b/drivers/cpuidle/cpuidle-calxeda.c
new file mode 100644
index 000000000000..e1aab38c5a8d
--- /dev/null
+++ b/drivers/cpuidle/cpuidle-calxeda.c
@@ -0,0 +1,161 @@
+/*
+ * Copyright 2012 Calxeda, Inc.
+ *
+ * Based on arch/arm/plat-mxc/cpuidle.c:
+ * Copyright 2012 Freescale Semiconductor, Inc.
+ * Copyright 2012 Linaro Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/cpuidle.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/time.h>
+#include <linux/delay.h>
+#include <linux/suspend.h>
+#include <asm/cpuidle.h>
+#include <asm/proc-fns.h>
+#include <asm/smp_scu.h>
+#include <asm/suspend.h>
+#include <asm/cacheflush.h>
+#include <asm/cp15.h>
+
+extern void highbank_set_cpu_jump(int cpu, void *jump_addr);
+extern void *scu_base_addr;
+
+static struct cpuidle_device __percpu *calxeda_idle_cpuidle_devices;
+
+static inline unsigned int get_auxcr(void)
+{
+        unsigned int val;
+        asm("mrc p15, 0, %0, c1, c0, 1  @ get AUXCR" : "=r" (val) : : "cc");
+        return val;
+}
+
+static inline void set_auxcr(unsigned int val)
+{
+        asm volatile("mcr p15, 0, %0, c1, c0, 1 @ set AUXCR"
+          : : "r" (val) : "cc");
+        isb();
+}
+
+static noinline void calxeda_idle_restore(void)
+{
+        set_cr(get_cr() | CR_C);
+        set_auxcr(get_auxcr() | 0x40);
+        scu_power_mode(scu_base_addr, SCU_PM_NORMAL);
+}
+
+static int calxeda_idle_finish(unsigned long val)
+{
+        /* Already flushed cache, but do it again as the outer cache functions
+         * dirty the cache with spinlocks */
+        flush_cache_all();
+
+        set_auxcr(get_auxcr() & ~0x40);
+        set_cr(get_cr() & ~CR_C);
+
+        scu_power_mode(scu_base_addr, SCU_PM_DORMANT);
+
+        cpu_do_idle();
+
+        /* Restore things if we didn't enter power-gating */
+        calxeda_idle_restore();
+        return 1;
+}
+
+static int calxeda_pwrdown_idle(struct cpuidle_device *dev,
+                                struct cpuidle_driver *drv,
+                                int index)
+{
+        highbank_set_cpu_jump(smp_processor_id(), cpu_resume);
+        cpu_suspend(0, calxeda_idle_finish);
+        return index;
+}
+
+static void calxeda_idle_cpuidle_devices_uninit(void)
+{
+        int i;
+        struct cpuidle_device *dev;
+
+        for_each_possible_cpu(i) {
+                dev = per_cpu_ptr(calxeda_idle_cpuidle_devices, i);
+                cpuidle_unregister_device(dev);
+        }
+
+        free_percpu(calxeda_idle_cpuidle_devices);
+}
+
+static struct cpuidle_driver calxeda_idle_driver = {
+        .name = "calxeda_idle",
+        .en_core_tk_irqen = 1,
+        .states = {
+                ARM_CPUIDLE_WFI_STATE,
+                {
+                        .name = "PG",
+                        .desc = "Power Gate",
+                        .flags = CPUIDLE_FLAG_TIME_VALID,
+                        .exit_latency = 30,
+                        .power_usage = 50,
+                        .target_residency = 200,
+                        .enter = calxeda_pwrdown_idle,
+                },
+        },
+        .state_count = 2,
+};
+
+static int __init calxeda_cpuidle_init(void)
+{
+        int cpu_id;
+        int ret;
+        struct cpuidle_device *dev;
+        struct cpuidle_driver *drv = &calxeda_idle_driver;
+
+        if (!of_machine_is_compatible("calxeda,highbank"))
+                return -ENODEV;
+
+        ret = cpuidle_register_driver(drv);
+        if (ret)
+                return ret;
+
+        calxeda_idle_cpuidle_devices = alloc_percpu(struct cpuidle_device);
+        if (calxeda_idle_cpuidle_devices == NULL) {
+                ret = -ENOMEM;
+                goto unregister_drv;
+        }
+
+        /* initialize state data for each cpuidle_device */
+        for_each_possible_cpu(cpu_id) {
+                dev = per_cpu_ptr(calxeda_idle_cpuidle_devices, cpu_id);
+                dev->cpu = cpu_id;
+                dev->state_count = drv->state_count;
+
+                ret = cpuidle_register_device(dev);
+                if (ret) {
+                        pr_err("Failed to register cpu %u, error: %d\n",
+                               cpu_id, ret);
+                        goto uninit;
+                }
+        }
+
+        return 0;
+
+uninit:
+        calxeda_idle_cpuidle_devices_uninit();
+unregister_drv:
+        cpuidle_unregister_driver(drv);
+        return ret;
+}
+module_init(calxeda_cpuidle_init);