net: airoha: Add the capability to allocate hwfd buffers via reserved-memory

In some configurations QDMA blocks require a contiguous block of
system memory for hwfd buffers queue. Introduce the capability to allocate
hw buffers forwarding queue via the reserved-memory DTS property instead of
running dmam_alloc_coherent().

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250521-airopha-desc-sram-v3-3-a6e9b085b4f0@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/drivers/net/ethernet/airoha/airoha_eth.c b/drivers/net/ethernet/airoha/airoha_eth.c
index 1ed43a5c629fd7a174792d5b50dd2d6fb84d6362..8a8a6424c1dd608125443fb197370cf69335bfb2 100644 (file)
--- a/drivers/net/ethernet/airoha/airoha_eth.c
+++ b/drivers/net/ethernet/airoha/airoha_eth.c
@@ -5,6 +5,7 @@
  */
 #include <linux/of.h>
 #include <linux/of_net.h>
+#include <linux/of_reserved_mem.h>
 #include <linux/platform_device.h>
 #include <linux/tcp.h>
 #include <linux/u64_stats_sync.h>
@@ -1072,9 +1073,11 @@ static void airoha_qdma_cleanup_tx_queue(struct airoha_queue *q)
 static int airoha_qdma_init_hfwd_queues(struct airoha_qdma *qdma)
 {
        struct airoha_eth *eth = qdma->eth;
+       int id = qdma - &eth->qdma[0];
        dma_addr_t dma_addr;
+       const char *name;
+       int size, index;
        u32 status;
-       int size;
 
        size = HW_DSCP_NUM * sizeof(struct airoha_qdma_fwd_desc);
        if (!dmam_alloc_coherent(eth->dev, size, &dma_addr, GFP_KERNEL))
@@ -1082,10 +1085,34 @@ static int airoha_qdma_init_hfwd_queues(struct airoha_qdma *qdma)
 
        airoha_qdma_wr(qdma, REG_FWD_DSCP_BASE, dma_addr);
 
-       size = AIROHA_MAX_PACKET_SIZE * HW_DSCP_NUM;
-       if (!dmam_alloc_coherent(eth->dev, size, &dma_addr, GFP_KERNEL))
+       name = devm_kasprintf(eth->dev, GFP_KERNEL, "qdma%d-buf", id);
+       if (!name)
                return -ENOMEM;
 
+       index = of_property_match_string(eth->dev->of_node,
+                                        "memory-region-names", name);
+       if (index >= 0) {
+               struct reserved_mem *rmem;
+               struct device_node *np;
+
+               /* Consume reserved memory for hw forwarding buffers queue if
+                * available in the DTS
+                */
+               np = of_parse_phandle(eth->dev->of_node, "memory-region",
+                                     index);
+               if (!np)
+                       return -ENODEV;
+
+               rmem = of_reserved_mem_lookup(np);
+               of_node_put(np);
+               dma_addr = rmem->base;
+       } else {
+               size = AIROHA_MAX_PACKET_SIZE * HW_DSCP_NUM;
+               if (!dmam_alloc_coherent(eth->dev, size, &dma_addr,
+                                        GFP_KERNEL))
+                       return -ENOMEM;
+       }
+
        airoha_qdma_wr(qdma, REG_FWD_BUF_BASE, dma_addr);
 
        airoha_qdma_rmw(qdma, REG_HW_FWD_DSCP_CFG,