net: cadence_gem: Add support for extended descriptors

Add support for extended descriptors with optional 64bit
addressing and timestamping. QEMU will not yet provide
timestamps (always leaving the valid timestamp bit as zero).

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 20181011021931.4249-6-edgar.iglesias@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 52 insertions, 19 deletions

diff --git a/hw/net/cadence_gem.c b/hw/net/cadence_gem.c
index a59a36e..fa79baf 100644
--- a/hw/net/cadence_gem.c
+++ b/hw/net/cadence_gem.c
@@ -207,6 +207,9 @@
 #define GEM_NWCFG_BCAST_REJ    0x00000020 /* Reject broadcast packets */
 #define GEM_NWCFG_PROMISC      0x00000010 /* Accept all packets */
 
+#define GEM_DMACFG_ADDR_64B    (1U << 30)
+#define GEM_DMACFG_TX_BD_EXT   (1U << 29)
+#define GEM_DMACFG_RX_BD_EXT   (1U << 28)
 #define GEM_DMACFG_RBUFSZ_M    0x00FF0000 /* DMA RX Buffer Size mask */
 #define GEM_DMACFG_RBUFSZ_S    16         /* DMA RX Buffer Size shift */
 #define GEM_DMACFG_RBUFSZ_MUL  64         /* DMA RX Buffer Size multiplier */
@@ -302,9 +305,14 @@
 
 #define GEM_MODID_VALUE 0x00020118
 
-static inline unsigned tx_desc_get_buffer(uint32_t *desc)
+static inline uint64_t tx_desc_get_buffer(CadenceGEMState *s, uint32_t *desc)
 {
-    return desc[0];
+    uint64_t ret = desc[0];
+
+    if (s->regs[GEM_DMACFG] & GEM_DMACFG_ADDR_64B) {
+        ret |= (uint64_t)desc[2] << 32;
+    }
+    return ret;
 }
 
 static inline unsigned tx_desc_get_used(uint32_t *desc)
@@ -347,9 +355,30 @@ static inline void print_gem_tx_desc(uint32_t *desc, uint8_t queue)
     DB_PRINT("length:  %d\n", tx_desc_get_length(desc));
 }
 
-static inline unsigned rx_desc_get_buffer(uint32_t *desc)
+static inline uint64_t rx_desc_get_buffer(CadenceGEMState *s, uint32_t *desc)
 {
-    return desc[0] & ~0x3UL;
+    uint64_t ret = desc[0] & ~0x3UL;
+
+    if (s->regs[GEM_DMACFG] & GEM_DMACFG_ADDR_64B) {
+        ret |= (uint64_t)desc[2] << 32;
+    }
+    return ret;
+}
+
+static inline int gem_get_desc_len(CadenceGEMState *s, bool rx_n_tx)
+{
+    int ret = 2;
+
+    if (s->regs[GEM_DMACFG] & GEM_DMACFG_ADDR_64B) {
+        ret += 2;
+    }
+    if (s->regs[GEM_DMACFG] & (rx_n_tx ? GEM_DMACFG_RX_BD_EXT
+                                       : GEM_DMACFG_TX_BD_EXT)) {
+        ret += 2;
+    }
+
+    assert(ret <= DESC_MAX_NUM_WORDS);
+    return ret;
 }
 
 static inline unsigned rx_desc_get_wrap(uint32_t *desc)
@@ -419,7 +448,7 @@ static void gem_init_register_masks(CadenceGEMState *s)
     memset(&s->regs_ro[0], 0, sizeof(s->regs_ro));
     s->regs_ro[GEM_NWCTRL]   = 0xFFF80000;
     s->regs_ro[GEM_NWSTATUS] = 0xFFFFFFFF;
-    s->regs_ro[GEM_DMACFG]   = 0xFE00F000;
+    s->regs_ro[GEM_DMACFG]   = 0x8E00F000;
     s->regs_ro[GEM_TXSTATUS] = 0xFFFFFE08;
     s->regs_ro[GEM_RXQBASE]  = 0x00000003;
     s->regs_ro[GEM_TXQBASE]  = 0x00000003;
@@ -807,7 +836,8 @@ static void gem_get_rx_desc(CadenceGEMState *s, int q)
     DB_PRINT("read descriptor 0x%x\n", (unsigned)s->rx_desc_addr[q]);
     /* read current descriptor */
     cpu_physical_memory_read(s->rx_desc_addr[q],
-                             (uint8_t *)s->rx_desc[q], sizeof(s->rx_desc[q]));
+                             (uint8_t *)s->rx_desc[q],
+                             sizeof(uint32_t) * gem_get_desc_len(s, true));
 
     /* Descriptor owned by software ? */
     if (rx_desc_get_ownership(s->rx_desc[q]) == 1) {
@@ -926,9 +956,10 @@ static ssize_t gem_receive(NetClientState *nc, const uint8_t *buf, size_t size)
                 rx_desc_get_buffer(s->rx_desc[q]));
 
         /* Copy packet data to emulated DMA buffer */
-        cpu_physical_memory_write(rx_desc_get_buffer(s->rx_desc[q]) +
-                                                                 rxbuf_offset,
-                                  rxbuf_ptr, MIN(bytes_to_copy, rxbufsize));
+        cpu_physical_memory_write(rx_desc_get_buffer(s, s->rx_desc[q]) +
+                                                                  rxbuf_offset,
+                                  rxbuf_ptr,
+                                  MIN(bytes_to_copy, rxbufsize));
         rxbuf_ptr += MIN(bytes_to_copy, rxbufsize);
         bytes_to_copy -= MIN(bytes_to_copy, rxbufsize);
 
@@ -964,7 +995,7 @@ static ssize_t gem_receive(NetClientState *nc, const uint8_t *buf, size_t size)
         /* Descriptor write-back.  */
         cpu_physical_memory_write(s->rx_desc_addr[q],
                                   (uint8_t *)s->rx_desc[q],
-                                  sizeof(s->rx_desc[q]));
+                                  sizeof(uint32_t) * gem_get_desc_len(s, true));
 
         /* Next descriptor */
         if (rx_desc_get_wrap(s->rx_desc[q])) {
@@ -972,7 +1003,7 @@ static ssize_t gem_receive(NetClientState *nc, const uint8_t *buf, size_t size)
             s->rx_desc_addr[q] = s->regs[GEM_RXQBASE];
         } else {
             DB_PRINT("incrementing RX descriptor list\n");
-            s->rx_desc_addr[q] += 8;
+            s->rx_desc_addr[q] += 4 * gem_get_desc_len(s, true);
         }
 
         gem_get_rx_desc(s, q);
@@ -1069,7 +1100,8 @@ static void gem_transmit(CadenceGEMState *s)
 
         DB_PRINT("read descriptor 0x%" HWADDR_PRIx "\n", packet_desc_addr);
         cpu_physical_memory_read(packet_desc_addr,
-                                 (uint8_t *)desc, sizeof(desc));
+                                 (uint8_t *)desc,
+                                 sizeof(uint32_t) * gem_get_desc_len(s, false));
         /* Handle all descriptors owned by hardware */
         while (tx_desc_get_used(desc) == 0) {
 
@@ -1082,7 +1114,7 @@ static void gem_transmit(CadenceGEMState *s)
             /* The real hardware would eat this (and possibly crash).
              * For QEMU let's lend a helping hand.
              */
-            if ((tx_desc_get_buffer(desc) == 0) ||
+            if ((tx_desc_get_buffer(s, desc) == 0) ||
                 (tx_desc_get_length(desc) == 0)) {
                 DB_PRINT("Invalid TX descriptor @ 0x%x\n",
                          (unsigned)packet_desc_addr);
@@ -1101,7 +1133,7 @@ static void gem_transmit(CadenceGEMState *s)
             /* Gather this fragment of the packet from "dma memory" to our
              * contig buffer.
              */
-            cpu_physical_memory_read(tx_desc_get_buffer(desc), p,
+            cpu_physical_memory_read(tx_desc_get_buffer(s, desc), p,
                                      tx_desc_get_length(desc));
             p += tx_desc_get_length(desc);
             total_bytes += tx_desc_get_length(desc);
@@ -1124,7 +1156,8 @@ static void gem_transmit(CadenceGEMState *s)
                 if (tx_desc_get_wrap(desc)) {
                     s->tx_desc_addr[q] = s->regs[GEM_TXQBASE];
                 } else {
-                    s->tx_desc_addr[q] = packet_desc_addr + 8;
+                    s->tx_desc_addr[q] = packet_desc_addr +
+                                         4 * gem_get_desc_len(s, false);
                 }
                 DB_PRINT("TX descriptor next: 0x%08x\n", s->tx_desc_addr[q]);
 
@@ -1168,11 +1201,11 @@ static void gem_transmit(CadenceGEMState *s)
                 tx_desc_set_last(desc);
                 packet_desc_addr = s->regs[GEM_TXQBASE];
             } else {
-                packet_desc_addr += 8;
+                packet_desc_addr += 4 * gem_get_desc_len(s, false);
             }
             DB_PRINT("read descriptor 0x%" HWADDR_PRIx "\n", packet_desc_addr);
-            cpu_physical_memory_read(packet_desc_addr,
-                                     (uint8_t *)desc, sizeof(desc));
+            cpu_physical_memory_read(packet_desc_addr, (uint8_t *)desc,
+                                sizeof(uint32_t) * gem_get_desc_len(s, false));
         }
 
         if (tx_desc_get_used(desc)) {
diff --git a/include/hw/net/cadence_gem.h b/include/hw/net/cadence_gem.h
index b33ef65..00dbf4f 100644
--- a/include/hw/net/cadence_gem.h
+++ b/include/hw/net/cadence_gem.h
@@ -33,7 +33,7 @@
 #define CADENCE_GEM_MAXREG        (0x00000800 / 4) /* Last valid GEM address */
 
 /* Max number of words in a DMA descriptor.  */
-#define DESC_MAX_NUM_WORDS              2
+#define DESC_MAX_NUM_WORDS              6
 
 #define MAX_PRIORITY_QUEUES             8
 #define MAX_TYPE1_SCREENERS             16