net: ethernet: enc28j60: support half-duplex SPI controllers

The current spi_read_buf function fails on SPI host masters which
are only half-duplex capable. Splitting the Tx and Rx part solves
this issue.

Tested on Raspberry Pi (full duplex) and I2SE Duckbill (half duplex).

Signed-off-by: Michael Heimpold <mhei@heimpold.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/microchip/enc28j60.c b/drivers/net/ethernet/microchip/enc28j60.c
index 86ea17e..b723622 100644 (file)
--- a/drivers/net/ethernet/microchip/enc28j60.c
+++ b/drivers/net/ethernet/microchip/enc28j60.c
@@ -89,22 +89,26 @@ spi_read_buf(struct enc28j60_net *priv, int len, u8 *data)
 {
        u8 *rx_buf = priv->spi_transfer_buf + 4;
        u8 *tx_buf = priv->spi_transfer_buf;
-       struct spi_transfer t = {
+       struct spi_transfer tx = {
                .tx_buf = tx_buf,
+               .len = SPI_OPLEN,
+       };
+       struct spi_transfer rx = {
                .rx_buf = rx_buf,
-               .len = SPI_OPLEN + len,
+               .len = len,
        };
        struct spi_message msg;
        int ret;
 
        tx_buf[0] = ENC28J60_READ_BUF_MEM;
-       tx_buf[1] = tx_buf[2] = tx_buf[3] = 0;  /* don't care */
 
        spi_message_init(&msg);
-       spi_message_add_tail(&t, &msg);
+       spi_message_add_tail(&tx, &msg);
+       spi_message_add_tail(&rx, &msg);
+
        ret = spi_sync(priv->spi, &msg);
        if (ret == 0) {
-               memcpy(data, &rx_buf[SPI_OPLEN], len);
+               memcpy(data, rx_buf, len);
                ret = msg.status;
        }
        if (ret && netif_msg_drv(priv))