soc: fsl: dpio: add Net DIM integration

Use the generic dynamic interrupt moderation (dim) framework to
implement adaptive interrupt coalescing on Rx. With the per-packet
interrupt scheme, a high interrupt rate has been noted for moderate
traffic flows leading to high CPU utilization.

The dpio driver exports new functions to enable/disable adaptive IRQ
coalescing on a DPIO object, to query the state or to update Net DIM
with a new set of bytes and frames dequeued.

Signed-off-by: Ioana Ciornei <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/soc/fsl/Kconfig

···
         tristate "QorIQ DPAA2 DPIO driver"
         depends on FSL_MC_BUS
         select SOC_BUS
+        select DIMLIB
         help
 	  Driver for the DPAA2 DPIO object.  A DPIO provides queue and
 	  buffer management facilities for software to interact with

drivers/soc/fsl/dpio/dpio-service.c

···
 #include <linux/platform_device.h>
 #include <linux/interrupt.h>
 #include <linux/dma-mapping.h>
+#include <linux/dim.h>
 #include <linux/slab.h>
 
 #include "dpio.h"
···
 	spinlock_t lock_notifications;
 	struct list_head notifications;
 	struct device *dev;
+
+	/* Net DIM */
+	struct dim rx_dim;
+	/* protect against concurrent Net DIM updates */
+	spinlock_t dim_lock;
+	u16 event_ctr;
+	u64 bytes;
+	u64 frames;
 };
 
 struct dpaa2_io_store {
···
 }
 EXPORT_SYMBOL_GPL(dpaa2_io_service_select);
 
+static void dpaa2_io_dim_work(struct work_struct *w)
+{
+	struct dim *dim = container_of(w, struct dim, work);
+	struct dim_cq_moder moder =
+		net_dim_get_rx_moderation(dim->mode, dim->profile_ix);
+	struct dpaa2_io *d = container_of(dim, struct dpaa2_io, rx_dim);
+
+	dpaa2_io_set_irq_coalescing(d, moder.usec);
+	dim->state = DIM_START_MEASURE;
+}
+
 /**
  * dpaa2_io_create() - create a dpaa2_io object.
  * @desc: the dpaa2_io descriptor
···
 	INIT_LIST_HEAD(&obj->node);
 	spin_lock_init(&obj->lock_mgmt_cmd);
 	spin_lock_init(&obj->lock_notifications);
+	spin_lock_init(&obj->dim_lock);
 	INIT_LIST_HEAD(&obj->notifications);
 
 	/* For now only enable DQRR interrupts */
···
 	spin_unlock(&dpio_list_lock);
 
 	obj->dev = dev;
+
+	memset(&obj->rx_dim, 0, sizeof(obj->rx_dim));
+	INIT_WORK(&obj->rx_dim.work, dpaa2_io_dim_work);
+	obj->event_ctr = 0;
+	obj->bytes = 0;
+	obj->frames = 0;
 
 	return obj;
 }
···
 	int max = 0;
 	struct qbman_swp *swp;
 	u32 status;
+
+	obj->event_ctr++;
 
 	swp = obj->swp;
 	status = qbman_swp_interrupt_read_status(swp);
···
 	qbman_swp_get_irq_coalescing(swp, NULL, irq_holdoff);
 }
 EXPORT_SYMBOL(dpaa2_io_get_irq_coalescing);
+
+/**
+ * dpaa2_io_set_adaptive_coalescing() - Enable/disable adaptive coalescing
+ * @d: the given DPIO object
+ * @use_adaptive_rx_coalesce: adaptive coalescing state
+ */
+void dpaa2_io_set_adaptive_coalescing(struct dpaa2_io *d,
+				      int use_adaptive_rx_coalesce)
+{
+	d->swp->use_adaptive_rx_coalesce = use_adaptive_rx_coalesce;
+}
+EXPORT_SYMBOL(dpaa2_io_set_adaptive_coalescing);
+
+/**
+ * dpaa2_io_get_adaptive_coalescing() - Query adaptive coalescing state
+ * @d: the given DPIO object
+ *
+ * Return 1 when adaptive coalescing is enabled on the DPIO object and 0
+ * otherwise.
+ */
+int dpaa2_io_get_adaptive_coalescing(struct dpaa2_io *d)
+{
+	return d->swp->use_adaptive_rx_coalesce;
+}
+EXPORT_SYMBOL(dpaa2_io_get_adaptive_coalescing);
+
+/**
+ * dpaa2_io_update_net_dim() - Update Net DIM
+ * @d: the given DPIO object
+ * @frames: how many frames have been dequeued by the user since the last call
+ * @bytes: how many bytes have been dequeued by the user since the last call
+ */
+void dpaa2_io_update_net_dim(struct dpaa2_io *d, __u64 frames, __u64 bytes)
+{
+	struct dim_sample dim_sample = {};
+
+	if (!d->swp->use_adaptive_rx_coalesce)
+		return;
+
+	spin_lock(&d->dim_lock);
+
+	d->bytes += bytes;
+	d->frames += frames;
+
+	dim_update_sample(d->event_ctr, d->frames, d->bytes, &dim_sample);
+	net_dim(&d->rx_dim, dim_sample);
+
+	spin_unlock(&d->dim_lock);
+}
+EXPORT_SYMBOL(dpaa2_io_update_net_dim);

drivers/soc/fsl/dpio/qbman-portal.h

···
 	/* Interrupt coalescing */
 	u32 irq_threshold;
 	u32 irq_holdoff;
+	int use_adaptive_rx_coalesce;
 };
 
 /* Function pointers */

include/soc/fsl/dpaa2-io.h

···
 
 int dpaa2_io_set_irq_coalescing(struct dpaa2_io *d, u32 irq_holdoff);
 void dpaa2_io_get_irq_coalescing(struct dpaa2_io *d, u32 *irq_holdoff);
-
+void dpaa2_io_set_adaptive_coalescing(struct dpaa2_io *d,
+				      int use_adaptive_rx_coalesce);
+int dpaa2_io_get_adaptive_coalescing(struct dpaa2_io *d);
+void dpaa2_io_update_net_dim(struct dpaa2_io *d, __u64 frames, __u64 bytes);
 #endif /* __FSL_DPAA2_IO_H */