dm9000: add checksum offload support

Add checksum offload support for DM9000A and DM9000B chips.

v2 changes: added a local copy of ip_summed to save IO cycles in dm9000_send_packet
v3 changes: trans_start updating is removed.

Signed-off-by: Yeasah Pell <yeasah@comrex.com>
Signed-off-by: Mike Rapoport <mike@compulab.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 108 insertions, 17 deletions

diff --git a/drivers/net/dm9000.c b/drivers/net/dm9000.c
index ffd9edceb317..8603806be898 100644
--- a/drivers/net/dm9000.c
+++ b/drivers/net/dm9000.c
@@ -92,6 +92,7 @@ typedef struct board_info {
         u16             tx_pkt_cnt;
         u16             queue_pkt_len;
         u16             queue_start_addr;
+        u16             queue_ip_summed;
         u16             dbug_cnt;
         u8              io_mode;                /* 0:word, 2:byte */
         u8              phy_addr;
@@ -124,6 +125,10 @@ typedef struct board_info {
 
         struct mii_if_info mii;
         u32             msg_enable;
+
+        int             rx_csum;
+        int             can_csum;
+        int             ip_summed;
 } board_info_t;
 
 /* debug code */
@@ -460,6 +465,40 @@ static int dm9000_nway_reset(struct net_device *dev)
         return mii_nway_restart(&dm->mii);
 }
 
+static uint32_t dm9000_get_rx_csum(struct net_device *dev)
+{
+        board_info_t *dm = to_dm9000_board(dev);
+        return dm->rx_csum;
+}
+
+static int dm9000_set_rx_csum(struct net_device *dev, uint32_t data)
+{
+        board_info_t *dm = to_dm9000_board(dev);
+        unsigned long flags;
+
+        if (dm->can_csum) {
+                dm->rx_csum = data;
+
+                spin_lock_irqsave(&dm->lock, flags);
+                iow(dm, DM9000_RCSR, dm->rx_csum ? RCSR_CSUM : 0);
+                spin_unlock_irqrestore(&dm->lock, flags);
+
+                return 0;
+        }
+
+        return -EOPNOTSUPP;
+}
+
+static int dm9000_set_tx_csum(struct net_device *dev, uint32_t data)
+{
+        board_info_t *dm = to_dm9000_board(dev);
+        int ret = -EOPNOTSUPP;
+
+        if (dm->can_csum)
+                ret = ethtool_op_set_tx_csum(dev, data);
+        return ret;
+}
+
 static u32 dm9000_get_link(struct net_device *dev)
 {
         board_info_t *dm = to_dm9000_board(dev);
@@ -540,6 +579,10 @@ static const struct ethtool_ops dm9000_ethtool_ops = {
         .get_eeprom_len         = dm9000_get_eeprom_len,
         .get_eeprom             = dm9000_get_eeprom,
         .set_eeprom             = dm9000_set_eeprom,
+        .get_rx_csum            = dm9000_get_rx_csum,
+        .set_rx_csum            = dm9000_set_rx_csum,
+        .get_tx_csum            = ethtool_op_get_tx_csum,
+        .set_tx_csum            = dm9000_set_tx_csum,
 };
 
 static void dm9000_show_carrier(board_info_t *db,
@@ -685,6 +728,9 @@ dm9000_init_dm9000(struct net_device *dev)
         /* I/O mode */
         db->io_mode = ior(db, DM9000_ISR) >> 6; /* ISR bit7:6 keeps I/O mode */
 
+        /* Checksum mode */
+        dm9000_set_rx_csum(dev, db->rx_csum);
+
         /* GPIO0 on pre-activate PHY */
         iow(db, DM9000_GPR, 0); /* REG_1F bit0 activate phyxcer */
         iow(db, DM9000_GPCR, GPCR_GEP_CNTL);    /* Let GPIO0 output */
@@ -743,6 +789,29 @@ static void dm9000_timeout(struct net_device *dev)
         spin_unlock_irqrestore(&db->lock, flags);
 }
 
+static void dm9000_send_packet(struct net_device *dev,
+                               int ip_summed,
+                               u16 pkt_len)
+{
+        board_info_t *dm = to_dm9000_board(dev);
+
+        /* The DM9000 is not smart enough to leave fragmented packets alone. */
+        if (dm->ip_summed != ip_summed) {
+                if (ip_summed == CHECKSUM_NONE)
+                        iow(dm, DM9000_TCCR, 0);
+                else
+                        iow(dm, DM9000_TCCR, TCCR_IP | TCCR_UDP | TCCR_TCP);
+                dm->ip_summed = ip_summed;
+        }
+
+        /* Set TX length to DM9000 */
+        iow(dm, DM9000_TXPLL, pkt_len);
+        iow(dm, DM9000_TXPLH, pkt_len >> 8);
+
+        /* Issue TX polling command */
+        iow(dm, DM9000_TCR, TCR_TXREQ); /* Cleared after TX complete */
+}
+
 /*
  *  Hardware start transmission.
  *  Send a packet to media from the upper layer.
@@ -769,17 +838,11 @@ dm9000_start_xmit(struct sk_buff *skb, struct net_device *dev)
         db->tx_pkt_cnt++;
         /* TX control: First packet immediately send, second packet queue */
         if (db->tx_pkt_cnt == 1) {
-                /* Set TX length to DM9000 */
-                iow(db, DM9000_TXPLL, skb->len);
-                iow(db, DM9000_TXPLH, skb->len >> 8);
-
-                /* Issue TX polling command */
-                iow(db, DM9000_TCR, TCR_TXREQ); /* Cleared after TX complete */
-
-                dev->trans_start = jiffies;     /* save the time stamp */
+                dm9000_send_packet(dev, skb->ip_summed, skb->len);
         } else {
                 /* Second packet */
                 db->queue_pkt_len = skb->len;
+                db->queue_ip_summed = skb->ip_summed;
                 netif_stop_queue(dev);
         }
 
@@ -809,12 +872,9 @@ static void dm9000_tx_done(struct net_device *dev, board_info_t *db)
                         dev_dbg(db->dev, "tx done, NSR %02x\n", tx_status);
 
                 /* Queue packet check & send */
-                if (db->tx_pkt_cnt > 0) {
-                        iow(db, DM9000_TXPLL, db->queue_pkt_len);
-                        iow(db, DM9000_TXPLH, db->queue_pkt_len >> 8);
-                        iow(db, DM9000_TCR, TCR_TXREQ);
-                        dev->trans_start = jiffies;
-                }
+                if (db->tx_pkt_cnt > 0)
+                        dm9000_send_packet(dev, db->queue_ip_summed,
+                                           db->queue_pkt_len);
                 netif_wake_queue(dev);
         }
 }
@@ -846,14 +906,14 @@ dm9000_rx(struct net_device *dev)
                 rxbyte = readb(db->io_data);
 
                 /* Status check: this byte must be 0 or 1 */
-                if (rxbyte > DM9000_PKT_RDY) {
+                if (rxbyte & DM9000_PKT_ERR) {
                         dev_warn(db->dev, "status check fail: %d\n", rxbyte);
                         iow(db, DM9000_RCR, 0x00);      /* Stop Device */
                         iow(db, DM9000_ISR, IMR_PAR);   /* Stop INT request */
                         return;
                 }
 
-                if (rxbyte != DM9000_PKT_RDY)
+                if (!(rxbyte & DM9000_PKT_RDY))
                         return;
 
                 /* A packet ready now  & Get status/length */
@@ -914,6 +974,12 @@ dm9000_rx(struct net_device *dev)
 
                         /* Pass to upper layer */
                         skb->protocol = eth_type_trans(skb, dev);
+                        if (db->rx_csum) {
+                                if ((((rxbyte & 0x1c) << 3) & rxbyte) == 0)
+                                        skb->ip_summed = CHECKSUM_UNNECESSARY;
+                                else
+                                        skb->ip_summed = CHECKSUM_NONE;
+                        }
                         netif_rx(skb);
                         dev->stats.rx_packets++;
 
@@ -922,7 +988,7 @@ dm9000_rx(struct net_device *dev)
 
                         (db->dumpblk)(db->io_data, RxLen);
                 }
-        } while (rxbyte == DM9000_PKT_RDY);
+        } while (rxbyte & DM9000_PKT_RDY);
 }
 
 static irqreturn_t dm9000_interrupt(int irq, void *dev_id)
@@ -1349,6 +1415,13 @@ dm9000_probe(struct platform_device *pdev)
                 db->type = TYPE_DM9000E;
         }
 
+        /* dm9000a/b are capable of hardware checksum offload */
+        if (db->type == TYPE_DM9000A || db->type == TYPE_DM9000B) {
+                db->can_csum = 1;
+                db->rx_csum = 1;
+                ndev->features |= NETIF_F_IP_CSUM;
+        }
+
         /* from this point we assume that we have found a DM9000 */
 
         /* driver system function */
diff --git a/drivers/net/dm9000.h b/drivers/net/dm9000.h
index ba25cf541420..80817c2edfb3 100644
--- a/drivers/net/dm9000.h
+++ b/drivers/net/dm9000.h
@@ -45,6 +45,10 @@
 #define DM9000_CHIPR           0x2C
 #define DM9000_SMCR            0x2F
 
+#define DM9000_ETXCSR          0x30
+#define DM9000_TCCR            0x31
+#define DM9000_RCSR            0x32
+
 #define CHIPR_DM9000A          0x19
 #define CHIPR_DM9000B          0x1B
 
@@ -131,7 +135,21 @@
 
 #define GPCR_GEP_CNTL       (1<<0)
 
+#define TCCR_IP             (1<<0)
+#define TCCR_TCP            (1<<1)
+#define TCCR_UDP            (1<<2)
+
+#define RCSR_UDP_BAD        (1<<7)
+#define RCSR_TCP_BAD        (1<<6)
+#define RCSR_IP_BAD         (1<<5)
+#define RCSR_UDP            (1<<4)
+#define RCSR_TCP            (1<<3)
+#define RCSR_IP             (1<<2)
+#define RCSR_CSUM           (1<<1)
+#define RCSR_DISCARD        (1<<0)
+
 #define DM9000_PKT_RDY          0x01    /* Packet ready to receive */
+#define DM9000_PKT_ERR          0x02
 #define DM9000_PKT_MAX          1536    /* Received packet max size */
 
 /* DM9000A / DM9000B definitions */