greybus: timesync: Add timesync core driver

This patch adds the core timesync functionality.

0. arche-platform.c/arche-apb-ctrl.c
   Modifies the platform layer to hook the incoming TIME_SYNC signal up to
   the timesync strobe IRQ handler. If the arche-platform driver can't
   satisfy the request for the wake-detect line, it will return -EAGAIN and
   the calling work-queue must reschedule the attempt to get exclusive
   access to the wake-detect pin logic. A private data field is added to
   the arche-platform driver to enable passing of a timesync pointer to the
   ISR responsible for synchronizing time.

1. timesync.c
   A new file added which contains all of the logic associated with sending
   greybus commands to SVC, APBx or Interfaces to enable, disable and
   disseminate timing information.

2. timesync_platform.c
   Any platform/arch specific code goes into timesync_platform.c.
   Originally the idea was to keep the x86 and ARM arch dependencies in a
   timesync_platform_arch.c file - however with further refinement that's
   currently not necessary however just-in-case it becomes necessary to
   resuscitate arch or platform specific methods for accessing timer
   resources that access shouldn't be part of the core timesync.c logic and
   so for the moment we access these timer resources through a thin access
   layer in timesync_platform.c. Expect this to go away long term ideally.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Acked-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

1 files changed, 62 insertions, 9 deletions

diff --git a/drivers/staging/greybus/arche-platform.c b/drivers/staging/greybus/arche-platform.c
index f47ea4670d25..31c952454cff 100644
--- a/drivers/staging/greybus/arche-platform.c
+++ b/drivers/staging/greybus/arche-platform.c
@@ -22,6 +22,7 @@
 #include <linux/suspend.h>
 #include <linux/time.h>
 #include "arche_platform.h"
+#include "greybus.h"
 
 #include <linux/usb/usb3613.h>
 
@@ -34,6 +35,7 @@ enum svc_wakedetect_state {
 	WD_STATE_STANDBYBOOT_TRIG,	/* As of now not used ?? */
 	WD_STATE_COLDBOOT_START,	/* Cold boot process started */
 	WD_STATE_STANDBYBOOT_START,	/* Not used */
+	WD_STATE_TIMESYNC,
 };
 
 struct arche_platform_drvdata {
@@ -57,13 +59,27 @@ struct arche_platform_drvdata {
 	int wake_detect_irq;
 	spinlock_t wake_lock;			/* Protect wake_detect_state */
 	struct mutex platform_state_mutex;	/* Protect state */
+	wait_queue_head_t wq;			/* WQ for arche_pdata->state */
 	unsigned long wake_detect_start;
 	struct notifier_block pm_notifier;
 
 	struct device *dev;
+	struct gb_timesync_svc *timesync_svc_pdata;
 };
 
-/* Requires calling context to hold arche_pdata->spinlock */
+static int arche_apb_bootret_assert(struct device *dev, void *data)
+{
+	apb_bootret_assert(dev);
+	return 0;
+}
+
+static int arche_apb_bootret_deassert(struct device *dev, void *data)
+{
+	apb_bootret_deassert(dev);
+	return 0;
+}
+
+/* Requires calling context to hold arche_pdata->platform_state_mutex */
 static void arche_platform_set_state(struct arche_platform_drvdata *arche_pdata,
 				     enum arche_platform_state state)
 {
@@ -94,7 +110,8 @@ static void arche_platform_set_state(struct arche_platform_drvdata *arche_pdata,
  * satisfy the requested state-transition or -EINVAL for all other
  * state-transition requests.
  */
-int arche_platform_change_state(enum arche_platform_state state)
+int arche_platform_change_state(enum arche_platform_state state,
+				struct gb_timesync_svc *timesync_svc_pdata)
 {
 	struct arche_platform_drvdata *arche_pdata;
 	struct platform_device *pdev;
@@ -118,11 +135,6 @@ int arche_platform_change_state(enum arche_platform_state state)
 
 	mutex_lock(&arche_pdata->platform_state_mutex);
 	spin_lock_irqsave(&arche_pdata->wake_lock, flags);
-	if (arche_pdata->wake_detect_state != WD_STATE_IDLE) {
-		dev_err(arche_pdata->dev,
-			"driver busy with wake/detect line ops\n");
-		goto  exit;
-	}
 
 	if (arche_pdata->state == state) {
 		ret = 0;
@@ -131,10 +143,27 @@ int arche_platform_change_state(enum arche_platform_state state)
 
 	switch (state) {
 	case ARCHE_PLATFORM_STATE_TIME_SYNC:
-		disable_irq(arche_pdata->wake_detect_irq);
+		if (arche_pdata->state != ARCHE_PLATFORM_STATE_ACTIVE) {
+			ret = -EINVAL;
+			goto exit;
+		}
+		if (arche_pdata->wake_detect_state != WD_STATE_IDLE) {
+			dev_err(arche_pdata->dev,
+				"driver busy with wake/detect line ops\n");
+			goto  exit;
+		}
+		device_for_each_child(arche_pdata->dev, NULL,
+				      arche_apb_bootret_assert);
+		arche_pdata->wake_detect_state = WD_STATE_TIMESYNC;
 		break;
 	case ARCHE_PLATFORM_STATE_ACTIVE:
-		enable_irq(arche_pdata->wake_detect_irq);
+		if (arche_pdata->state != ARCHE_PLATFORM_STATE_TIME_SYNC) {
+			ret = -EINVAL;
+			goto exit;
+		}
+		device_for_each_child(arche_pdata->dev, NULL,
+				      arche_apb_bootret_deassert);
+		arche_pdata->wake_detect_state = WD_STATE_IDLE;
 		break;
 	case ARCHE_PLATFORM_STATE_OFF:
 	case ARCHE_PLATFORM_STATE_STANDBY:
@@ -147,7 +176,11 @@ int arche_platform_change_state(enum arche_platform_state state)
 			"invalid state transition request\n");
 		goto exit;
 	}
+	arche_pdata->timesync_svc_pdata = timesync_svc_pdata;
 	arche_platform_set_state(arche_pdata, state);
+	if (state == ARCHE_PLATFORM_STATE_ACTIVE)
+		wake_up(&arche_pdata->wq);
+
 	ret = 0;
 exit:
 	spin_unlock_irqrestore(&arche_pdata->wake_lock, flags);
@@ -252,6 +285,11 @@ static irqreturn_t arche_platform_wd_irq(int irq, void *devid)
 
 	spin_lock_irqsave(&arche_pdata->wake_lock, flags);
 
+	if (arche_pdata->wake_detect_state == WD_STATE_TIMESYNC) {
+		gb_timesync_irq(arche_pdata->timesync_svc_pdata);
+		goto exit;
+	}
+
 	if (gpio_get_value(arche_pdata->wake_detect_gpio)) {
 		/* wake/detect rising */
 
@@ -293,6 +331,7 @@ static irqreturn_t arche_platform_wd_irq(int irq, void *devid)
 		}
 	}
 
+exit:
 	spin_unlock_irqrestore(&arche_pdata->wake_lock, flags);
 
 	return IRQ_HANDLED;
@@ -402,7 +441,17 @@ static ssize_t state_store(struct device *dev,
 	struct arche_platform_drvdata *arche_pdata = platform_get_drvdata(pdev);
 	int ret = 0;
 
+retry:
 	mutex_lock(&arche_pdata->platform_state_mutex);
+	if (arche_pdata->state == ARCHE_PLATFORM_STATE_TIME_SYNC) {
+		mutex_unlock(&arche_pdata->platform_state_mutex);
+		ret = wait_event_interruptible(
+			arche_pdata->wq,
+			arche_pdata->state != ARCHE_PLATFORM_STATE_TIME_SYNC);
+		if (ret)
+			return ret;
+		goto retry;
+	}
 
 	if (sysfs_streq(buf, "off")) {
 		if (arche_pdata->state == ARCHE_PLATFORM_STATE_OFF)
@@ -610,6 +659,7 @@ static int arche_platform_probe(struct platform_device *pdev)
 
 	spin_lock_init(&arche_pdata->wake_lock);
 	mutex_init(&arche_pdata->platform_state_mutex);
+	init_waitqueue_head(&arche_pdata->wq);
 	arche_pdata->wake_detect_irq =
 		gpio_to_irq(arche_pdata->wake_detect_gpio);
 
@@ -653,6 +703,9 @@ static int arche_platform_probe(struct platform_device *pdev)
 		goto err_populate;
 	}
 
+	/* Register callback pointer */
+	arche_platform_change_state_cb = arche_platform_change_state;
+
 	dev_info(dev, "Device registered successfully\n");
 	return 0;