remoteproc: remove the hardcoded vring alignment

Remove the hardcoded vring alignment of 4096 bytes,
and instead utilize tha vring alignment as specified in
the resource table.

This is needed for remote processors that have rigid
memory requirement, and which have found the alignment of
4096 bytes to be excessively big.

Signed-off-by: Ohad Ben-Cohen <[e-mail]>
Cc: Brian Swetland <[e-mail]>
Cc: Iliyan Malchev <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Grant Likely <[e-mail]>
Cc: Rusty Russell <[e-mail]>
Cc: Mark Grosen <[e-mail]>
Cc: John Williams <[e-mail]>
Cc: Michal Simek <[e-mail]>
Cc: Loic PALLARDY <[e-mail]>
Cc: Ludovic BARRE <[e-mail]>
Cc: Omar Ramirez Luna <[e-mail]>
Cc: Guzman Lugo Fernando <[e-mail]>
Cc: Anna Suman <[e-mail]>
Cc: Clark Rob <[e-mail]>
Cc: Stephen Boyd <[e-mail]>
Cc: Saravana Kannan <[e-mail]>
Cc: David Brown <[e-mail]>
Cc: Kieran Bingham <[e-mail]>
Cc: Tony Lindgren <[e-mail]>

drivers/remoteproc/remoteproc_core.c

···
 		return -EINVAL;
 	}
 
-	/* the firmware must provide the expected queue size */
-	if (!vring->num) {
-		dev_err(dev, "invalid qsz (%d)\n", vring->num);
+	/* verify queue size and vring alignment are sane */
+	if (!vring->num || !vring->align) {
+		dev_err(dev, "invalid qsz (%d) or alignment (%d)\n",
+						vring->num, vring->align);
 		return -EINVAL;
 	}
 
 	/* actual size of vring (in bytes) */
-	size = PAGE_ALIGN(vring_size(vring->num, AMP_VRING_ALIGN));
+	size = PAGE_ALIGN(vring_size(vring->num, vring->align));
 
 	if (!idr_pre_get(&rproc->notifyids, GFP_KERNEL)) {
 		dev_err(dev, "idr_pre_get failed\n");
···
 					dma, size, notifyid);
 
 	rvdev->vring[i].len = vring->num;
+	rvdev->vring[i].align = vring->align;
 	rvdev->vring[i].va = va;
 	rvdev->vring[i].dma = dma;
 	rvdev->vring[i].notifyid = notifyid;
···
 
 	for (i--; i > 0; i--) {
 		struct rproc_vring *rvring = &rvdev->vring[i];
-		int size = PAGE_ALIGN(vring_size(rvring->len, AMP_VRING_ALIGN));
+		int size = PAGE_ALIGN(vring_size(rvring->len, rvring->align));
 
 		dma_free_coherent(rproc->dev, size, rvring->va, rvring->dma);
 		idr_remove(&rproc->notifyids, rvring->notifyid);

drivers/remoteproc/remoteproc_virtio.c

···
 	 * Create the new vq, and tell virtio we're not interested in
 	 * the 'weak' smp barriers, since we're talking with a real device.
 	 */
-	vq = vring_new_virtqueue(len, AMP_VRING_ALIGN, vdev, false, addr,
+	vq = vring_new_virtqueue(len, rvring->align, vdev, false, addr,
 					rproc_virtio_notify, callback, name);
 	if (!vq) {
 		dev_err(rproc->dev, "vring_new_virtqueue %s failed\n", name);

include/linux/remoteproc.h

···
 #include <linux/completion.h>
 #include <linux/idr.h>
 
-/*
- * The alignment between the consumer and producer parts of the vring.
- * Note: this is part of the "wire" protocol. If you change this, you need
- * to update your peers too.
- */
-#define AMP_VRING_ALIGN	(4096)
-
 /**
  * struct resource_table - firmware resource table header
  * @ver: version number
···
  * @dma: dma address
  * @len: length, in bytes
  * @da: device address
+ * @align: vring alignment
  * @notifyid: rproc-specific unique vring index
  * @rvdev: remote vdev
  * @vq: the virtqueue of this vring
···
 	dma_addr_t dma;
 	int len;
 	u32 da;
+	u32 align;
 	int notifyid;
 	struct rproc_vdev *rvdev;
 	struct virtqueue *vq;