adc driver: create specific workqueue to execute DMA.

Application using the ADC driver may run with real-time scheduling and high priority. The default shared queue is running with non real-time scheduling policy. ADC crates its own workqueue, that one can adjust in terms of scheduling policy to fulfill application's real-time constraints.

adc driver: create specific workqueue to execute DMA.
Application using the ADC driver may run with real-time scheduling and high priority. The default shared queue is running with non real-time scheduling policy. ADC crates its own workqueue, that one can adjust in terms of scheduling policy to fulfill application's real-time constraints.
d313407c · Michel Arruat · Federico Vaga · 6970670a · d313407c · d313407c
Commit d313407c authored Mar 07, 2014 by Michel Arruat Committed by Federico Vaga Apr 07, 2014
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Showing with 33 additions and 12 deletions

fa-core.c kernel/fa-core.c +29 -11

fa-irq.c kernel/fa-irq.c +1 -1

fmc-adc.h kernel/fmc-adc.h +3 -0

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--- a/kernel/fa-core.c
+++ b/kernel/fa-core.c
@@ -10,6 +10,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
+#include <linux/workqueue.h>
 #include <linux/fmc.h>
 #include <linux/fmc-sdb.h>
@@ -35,6 +36,9 @@ static const int zfad_hw_range[] = {
 	[ZFA_RANGE_OPEN]  = 0x00,
 };
+/* fmc-adc specific workqueue */
+struct workqueue_struct *fa_workqueue;
 /*
 * zfad_convert_hw_range
 * @usr_val: range value
@@ -472,6 +476,7 @@ int fa_remove(struct fmc_device *fmc)
 	int i = ARRAY_SIZE(mods);
 	fa_free_irqs(fa);
+	flush_workqueue(fa_workqueue);
 	while (--i >= 0) {
 		m = mods + i;
@@ -505,24 +510,35 @@ static int fa_init(void)
 {
 	int ret;
+	fa_workqueue = alloc_workqueue(fa_dev_drv.driver.name,
+					WQ_NON_REENTRANT | WQ_UNBOUND | WQ_MEM_RECLAIM, 1);
+	if (fa_workqueue == NULL)
+		return -ENOMEM;
 	/* First trigger and zio driver */
 	ret = fa_trig_init();
 	if (ret)
-		return ret;
+		goto out1;
 	ret = fa_zio_register();
-	if (ret) {
+	if (ret)
-		fa_trig_exit();
+		goto out2;
-		return ret;
-	}
 	/* Finally the fmc driver, whose probe instantiates zio devices */
 	ret = fmc_driver_register(&fa_dev_drv);
-	if (ret) {
+	if (ret)
-		fa_trig_exit();
+		goto out3;
-		fa_zio_unregister();
-		return ret;
+	return ret;
-	}
-	return 0;
+out3:
+	fa_zio_unregister();
+out2:
+	fa_trig_exit();
+out1:
+	destroy_workqueue(fa_workqueue);
+	return ret;
 }
 static void fa_exit(void)
@@ -530,6 +546,8 @@ static void fa_exit(void)
 	fmc_driver_unregister(&fa_dev_drv);
 	fa_zio_unregister();
 	fa_trig_exit();
+	if (fa_workqueue != NULL)
+		destroy_workqueue(fa_workqueue);
 }
 module_init(fa_init);

--- a/kernel/fa-irq.c
+++ b/kernel/fa-irq.c
@@ -356,7 +356,7 @@ irqreturn_t fa_irq_handler(int irq_core_base, void *dev_id)
 		if (cset->flags & ZIO_CSET_BUSY) {
 			/* Job deferred to the workqueue: */
 			/* Start DMA and ack irq on the carrier */
-			schedule_work(&fa->irq_work);
+			queue_work(fa_workqueue, &fa->irq_work);
 			/* register the core firing the IRQ in order to */
 			/* check right IRQ seq.: ACQ_END followed by DMA_END */
 			fa->last_irq_core_src = irq_core_base;

--- a/kernel/fmc-adc.h
+++ b/kernel/fmc-adc.h
@@ -410,6 +410,9 @@ static inline void fa_writel(struct fa_dev *fa,
 	fmc_writel(fa->fmc, val, base_off+field->offset);
 }
+/* Global variable exported by fa-core.c */
+extern struct workqueue_struct *fa_workqueue;
 /* Global variable exported by fa-spec.c */
 extern struct fa_carrier_op fa_spec_op;