[PATCH 5/6] misc: fastrpc: Add extended context bank support

[Vinayak Katoch]

Extended context banks carry a 40-bit DMA mask and are shared across all
open sessions rather than exclusively owned by one. They are a
fundamentally different resource from normal CBs and do not belong in
the session[] pool.

Maintain a separate dynamically allocated cctx->ext_cb[] array instead.
Extended CBs are detected at probe time by the presence of a
memory-region phandle and routed there, leaving session[] and the normal
allocation path unchanged.

Signed-off-by: Vinayak Katoch <vinayak.katoch@xxxxxxxxxxxxxxxx>
---
 drivers/misc/fastrpc.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 07a0f2b229b4..28d89fd9cbbc 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -309,6 +309,8 @@ struct fastrpc_channel_ctx {
 	struct qcom_scm_vmperm vmperms[FASTRPC_MAX_VMIDS];
 	struct rpmsg_device *rpdev;
 	struct fastrpc_session_ctx session[FASTRPC_MAX_SESSIONS];
+	struct fastrpc_session_ctx **ext_cb;
+	int ext_cb_count;
 	spinlock_t lock;
 	struct idr ctx_idr;
 	struct list_head users;
@@ -536,9 +538,13 @@ static int fastrpc_remote_heap_alloc(struct fastrpc_user *fl, struct device *dev
 static void fastrpc_channel_ctx_free(struct kref *ref)
 {
 	struct fastrpc_channel_ctx *cctx;
+	int i;
 
 	cctx = container_of(ref, struct fastrpc_channel_ctx, refcount);
 
+	for (i = 0; i < cctx->ext_cb_count; i++)
+		kfree(cctx->ext_cb[i]);
+	kfree(cctx->ext_cb);
 	idr_destroy(&cctx->ctx_idr);
 	kfree(cctx);
 }
@@ -2373,6 +2379,8 @@ static int fastrpc_cb_init(struct platform_device *pdev)
 	u32 dma_bits;
 	u32 sid = 0;
 	int rc;
+	bool is_extended_cb = false;
+	struct device_node *mem_np;
 
 	cctx = dev_get_drvdata(dev->parent);
 	if (!cctx)
@@ -2382,6 +2390,45 @@ static int fastrpc_cb_init(struct platform_device *pdev)
 				       of_n_addr_cells(dev->of_node) - 1, &sid))
 		dev_info(dev, "FastRPC Session ID not specified in DT\n");
 
+	mem_np = of_parse_phandle(dev->of_node, "memory-region", 0);
+	if (mem_np) {
+		is_extended_cb = true;
+		of_node_put(mem_np);
+	}
+
+	if (is_extended_cb) {
+		struct fastrpc_session_ctx **new_ext;
+
+		sess = kzalloc_obj(*sess);
+		if (!sess)
+			return -ENOMEM;
+
+		spin_lock_irqsave(&cctx->lock, flags);
+		new_ext = krealloc(cctx->ext_cb,
+				   (cctx->ext_cb_count + 1) * sizeof(*cctx->ext_cb),
+				   GFP_KERNEL);
+		if (!new_ext) {
+			spin_unlock_irqrestore(&cctx->lock, flags);
+			kfree(sess);
+			return -ENOMEM;
+		}
+		cctx->ext_cb = new_ext;
+		sess->valid = true;
+		sess->dev = dev;
+		sess->sid = sid;
+		dev_set_drvdata(dev, sess);
+		cctx->ext_cb[cctx->ext_cb_count++] = sess;
+		spin_unlock_irqrestore(&cctx->lock, flags);
+
+		rc = dma_set_mask(dev, DMA_BIT_MASK(40));
+		if (rc) {
+			dev_err(dev, "40-bit DMA enable failed\n");
+			return rc;
+		}
+
+		return 0;
+	}
+
 	spin_lock_irqsave(&cctx->lock, flags);
 	if (cctx->sesscount >= FASTRPC_MAX_SESSIONS) {
 		spin_unlock_irqrestore(&cctx->lock, flags);

-- 
2.34.1