cpuidle: exynos: add coupled cpuidle support for exynos4210

The following patch adds coupled cpuidle support for Exynos4210 to
an existing cpuidle-exynos driver.  As a result it enables AFTR mode
to be used by default on Exynos4210 without the need to hot unplug
CPU1 first.

The patch is heavily based on earlier cpuidle-exynos4210 driver from
Daniel Lezcano:

http://www.spinics.net/lists/linux-samsung-soc/msg28134.html

Changes from Daniel's code include:
- porting code to current kernels
- fixing it to work on my setup (by using S5P_INFORM register
  instead of S5P_VA_SYSRAM one on Revison 1.1 and retrying poking
  CPU1 out of the BOOT ROM if necessary)
- fixing rare lockup caused by waiting for CPU1 to get stuck in
  the BOOT ROM (CPU hotplug code in arch/arm/mach-exynos/platsmp.c
  doesn't require this and works fine)
- moving Exynos specific code to arch/arm/mach-exynos/pm.c
- using cpu_boot_reg_base() helper instead of BOOT_VECTOR macro
- using exynos_cpu_*() helpers instead of accessing registers
  directly
- using arch_send_wakeup_ipi_mask() instead of dsb_sev()
  (this matches CPU hotplug code in arch/arm/mach-exynos/platsmp.c)
- integrating separate exynos4210-cpuidle driver into existing
  exynos-cpuidle one

Cc: Colin Cross <ccross@google.com>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Cc: Tomasz Figa <tomasz.figa@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Kukjin Kim <kgene@kernel.org>

1 files changed, 71 insertions, 5 deletions

diff --git a/drivers/cpuidle/cpuidle-exynos.c b/drivers/cpuidle/cpuidle-exynos.c
index 4003a3160865..26f5f29fdb03 100644
--- a/drivers/cpuidle/cpuidle-exynos.c
+++ b/drivers/cpuidle/cpuidle-exynos.c
@@ -1,8 +1,11 @@
-/* linux/arch/arm/mach-exynos/cpuidle.c
- *
- * Copyright (c) 2011 Samsung Electronics Co., Ltd.
+/*
+ * Copyright (c) 2011-2014 Samsung Electronics Co., Ltd.
  *              http://www.samsung.com
  *
+ * Coupled cpuidle support based on the work of:
+ *      Colin Cross <ccross@android.com>
+ *      Daniel Lezcano <daniel.lezcano@linaro.org>
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
@@ -13,13 +16,49 @@
 #include <linux/export.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/platform_data/cpuidle-exynos.h>
 
 #include <asm/proc-fns.h>
 #include <asm/suspend.h>
 #include <asm/cpuidle.h>
 
+static atomic_t exynos_idle_barrier;
+
+static struct cpuidle_exynos_data *exynos_cpuidle_pdata;
 static void (*exynos_enter_aftr)(void);
 
+static int exynos_enter_coupled_lowpower(struct cpuidle_device *dev,
+                                         struct cpuidle_driver *drv,
+                                         int index)
+{
+        int ret;
+
+        exynos_cpuidle_pdata->pre_enter_aftr();
+
+        /*
+         * Waiting all cpus to reach this point at the same moment
+         */
+        cpuidle_coupled_parallel_barrier(dev, &exynos_idle_barrier);
+
+        /*
+         * Both cpus will reach this point at the same time
+         */
+        ret = dev->cpu ? exynos_cpuidle_pdata->cpu1_powerdown()
+                       : exynos_cpuidle_pdata->cpu0_enter_aftr();
+        if (ret)
+                index = ret;
+
+        /*
+         * Waiting all cpus to finish the power sequence before going further
+         */
+        cpuidle_coupled_parallel_barrier(dev, &exynos_idle_barrier);
+
+        exynos_cpuidle_pdata->post_enter_aftr();
+
+        return index;
+}
+
 static int exynos_enter_lowpower(struct cpuidle_device *dev,
                                 struct cpuidle_driver *drv,
                                 int index)
@@ -55,13 +94,40 @@ static struct cpuidle_driver exynos_idle_driver = {
         .safe_state_index = 0,
 };
 
+static struct cpuidle_driver exynos_coupled_idle_driver = {
+        .name                   = "exynos_coupled_idle",
+        .owner                  = THIS_MODULE,
+        .states = {
+                [0] = ARM_CPUIDLE_WFI_STATE,
+                [1] = {
+                        .enter                  = exynos_enter_coupled_lowpower,
+                        .exit_latency           = 5000,
+                        .target_residency       = 10000,
+                        .flags                  = CPUIDLE_FLAG_COUPLED |
+                                                  CPUIDLE_FLAG_TIMER_STOP,
+                        .name                   = "C1",
+                        .desc                   = "ARM power down",
+                },
+        },
+        .state_count = 2,
+        .safe_state_index = 0,
+};
+
 static int exynos_cpuidle_probe(struct platform_device *pdev)
 {
         int ret;
 
-        exynos_enter_aftr = (void *)(pdev->dev.platform_data);
+        if (of_machine_is_compatible("samsung,exynos4210")) {
+                exynos_cpuidle_pdata = pdev->dev.platform_data;
+
+                ret = cpuidle_register(&exynos_coupled_idle_driver,
+                                       cpu_possible_mask);
+        } else {
+                exynos_enter_aftr = (void *)(pdev->dev.platform_data);
+
+                ret = cpuidle_register(&exynos_idle_driver, NULL);
+        }
 
-        ret = cpuidle_register(&exynos_idle_driver, NULL);
         if (ret) {
                 dev_err(&pdev->dev, "failed to register cpuidle driver\n");
                 return ret;