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[Qemu-devel] [PATCH v3 06/30] imx_fec: Emulate SHIFT16 in ENETx_RACC


From: Andrey Smirnov
Subject: [Qemu-devel] [PATCH v3 06/30] imx_fec: Emulate SHIFT16 in ENETx_RACC
Date: Mon, 6 Nov 2017 07:47:49 -0800

Needed to support latest Linux kernel driver which relies on that
functionality.

Cc: Peter Maydell <address@hidden>
Cc: Jason Wang <address@hidden>
Cc: Philippe Mathieu-Daudé <address@hidden>
Cc: address@hidden
Cc: address@hidden
Cc: address@hidden
Reviewed-by: Peter Maydell <address@hidden>
Signed-off-by: Andrey Smirnov <address@hidden>
---
 hw/net/imx_fec.c         | 23 +++++++++++++++++++++++
 include/hw/net/imx_fec.h |  2 ++
 2 files changed, 25 insertions(+)

diff --git a/hw/net/imx_fec.c b/hw/net/imx_fec.c
index 18de508e8c..131e7fd734 100644
--- a/hw/net/imx_fec.c
+++ b/hw/net/imx_fec.c
@@ -1037,6 +1037,7 @@ static ssize_t imx_enet_receive(NetClientState *nc, const 
uint8_t *buf,
     uint8_t *crc_ptr;
     unsigned int buf_len;
     size_t size = len;
+    bool shift16 = s->regs[ENET_RACC] & ENET_RACC_SHIFT16;
 
     FEC_PRINTF("len %d\n", (int)size);
 
@@ -1051,6 +1052,10 @@ static ssize_t imx_enet_receive(NetClientState *nc, 
const uint8_t *buf,
     crc = cpu_to_be32(crc32(~0, buf, size));
     crc_ptr = (uint8_t *) &crc;
 
+    if (shift16) {
+        size += 2;
+    }
+
     /* Huge frames are truncted.  */
     if (size > s->regs[ENET_FTRL]) {
         size = s->regs[ENET_FTRL];
@@ -1087,6 +1092,24 @@ static ssize_t imx_enet_receive(NetClientState *nc, 
const uint8_t *buf,
             buf_len += size - 4;
         }
         buf_addr = bd.data;
+
+        if (shift16) {
+            /*
+             * If SHIFT16 bit of ENETx_RACC register is set we need to
+             * align the payload to 4-byte boundary.
+             */
+            const uint8_t zeros[2] = { 0 };
+
+            dma_memory_write(&address_space_memory, buf_addr,
+                             zeros, sizeof(zeros));
+
+            buf_addr += sizeof(zeros);
+            buf_len  -= sizeof(zeros);
+
+            /* We only do this once per Ethernet frame */
+            shift16 = false;
+        }
+
         dma_memory_write(&address_space_memory, buf_addr, buf, buf_len);
         buf += buf_len;
         if (size < 4) {
diff --git a/include/hw/net/imx_fec.h b/include/hw/net/imx_fec.h
index 0fcc4f0c71..e482d1c13b 100644
--- a/include/hw/net/imx_fec.h
+++ b/include/hw/net/imx_fec.h
@@ -170,6 +170,8 @@
 #define ENET_TWFR_TFWR_LENGTH  (6)
 #define ENET_TWFR_STRFWD       (1 << 8)
 
+#define ENET_RACC_SHIFT16      BIT(7)
+
 /* Buffer Descriptor.  */
 typedef struct {
     uint16_t length;
-- 
2.13.6




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