can: mcp251xfd: tef-path: reduce number of SPI core requests to set UINC bit

Reduce the number of separate SPI core requests when setting the UINC bit in
the TEF FIFO, and instead batch them up into a single SPI core request.

Link: https://lore.kernel.org/r/20201126132144.351154-6-mkl@pengutronix.de
Tested-by: Thomas Kopp <thomas.kopp@microchip.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
index 551499d9737f73ed623d3a00a6b6d2b9a97aba48..20cbd5c446f52e1e052d53d59339907108487393 100644 (file)
--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
@@ -340,6 +340,23 @@ static void mcp251xfd_ring_init(struct mcp251xfd_priv *priv)
        tef_ring->head = 0;
        tef_ring->tail = 0;
 
+       /* FIFO increment TEF tail pointer */
+       addr = MCP251XFD_REG_TEFCON;
+       val = MCP251XFD_REG_TEFCON_UINC;
+       len = mcp251xfd_cmd_prepare_write_reg(priv, &tef_ring->uinc_buf,
+                                             addr, val, val);
+
+       for (j = 0; j < ARRAY_SIZE(tef_ring->uinc_xfer); j++) {
+               struct spi_transfer *xfer;
+
+               xfer = &tef_ring->uinc_xfer[j];
+               xfer->tx_buf = &tef_ring->uinc_buf;
+               xfer->len = len;
+               xfer->cs_change = 1;
+               xfer->cs_change_delay.value = 0;
+               xfer->cs_change_delay.unit = SPI_DELAY_UNIT_NSECS;
+       }
+
        /* TX */
        tx_ring = priv->tx;
        tx_ring->head = 0;
@@ -1231,10 +1248,8 @@ static int
 mcp251xfd_handle_tefif_one(struct mcp251xfd_priv *priv,
                           const struct mcp251xfd_hw_tef_obj *hw_tef_obj)
 {
-       struct mcp251xfd_tx_ring *tx_ring = priv->tx;
        struct net_device_stats *stats = &priv->ndev->stats;
        u32 seq, seq_masked, tef_tail_masked;
-       int err;
 
        seq = FIELD_GET(MCP251XFD_OBJ_FLAGS_SEQ_MCP2518FD_MASK,
                        hw_tef_obj->flags);
@@ -1255,18 +1270,9 @@ mcp251xfd_handle_tefif_one(struct mcp251xfd_priv *priv,
                                            mcp251xfd_get_tef_tail(priv),
                                            hw_tef_obj->ts);
        stats->tx_packets++;
-
-       /* finally increment the TEF pointer */
-       err = regmap_update_bits(priv->map_reg, MCP251XFD_REG_TEFCON,
-                                GENMASK(15, 8),
-                                MCP251XFD_REG_TEFCON_UINC);
-       if (err)
-               return err;
-
        priv->tef->tail++;
-       tx_ring->tail++;
 
-       return mcp251xfd_check_tef_tail(priv);
+       return 0;
 }
 
 static int mcp251xfd_tef_ring_update(struct mcp251xfd_priv *priv)
@@ -1353,6 +1359,40 @@ static int mcp251xfd_handle_tefif(struct mcp251xfd_priv *priv)
        }
 
  out_netif_wake_queue:
+       len = i;        /* number of handled goods TEFs */
+       if (len) {
+               struct mcp251xfd_tef_ring *ring = priv->tef;
+               struct mcp251xfd_tx_ring *tx_ring = priv->tx;
+               struct spi_transfer *last_xfer;
+
+               tx_ring->tail += len;
+
+               /* Increment the TEF FIFO tail pointer 'len' times in
+                * a single SPI message.
+                */
+
+               /* Note:
+                *
+                * "cs_change == 1" on the last transfer results in an
+                * active chip select after the complete SPI
+                * message. This causes the controller to interpret
+                * the next register access as data. Temporary set
+                * "cs_change" of the last transfer to "0" to properly
+                * deactivate the chip select at the end of the
+                * message.
+                */
+               last_xfer = &ring->uinc_xfer[len - 1];
+               last_xfer->cs_change = 0;
+               err = spi_sync_transfer(priv->spi, ring->uinc_xfer, len);
+               last_xfer->cs_change = 1;
+               if (err)
+                       return err;
+
+               err = mcp251xfd_check_tef_tail(priv);
+               if (err)
+                       return err;
+       }
+
        mcp251xfd_ecc_tefif_successful(priv);
 
        if (mcp251xfd_get_tx_free(priv->tx)) {

diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd.h b/drivers/net/can/spi/mcp251xfd/mcp251xfd.h
index 299dbf72e24bd9eaa6547e43369228f0619631b8..cb6398c2a5606cad5dac3d06f915481b63722b6d 100644 (file)
--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd.h
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd.h
@@ -504,6 +504,9 @@ struct mcp251xfd_tef_ring {
 
        /* u8 obj_num equals tx_ring->obj_num */
        /* u8 obj_size equals sizeof(struct mcp251xfd_hw_tef_obj) */
+
+       union mcp251xfd_write_reg_buf uinc_buf;
+       struct spi_transfer uinc_xfer[MCP251XFD_TX_OBJ_NUM_MAX];
 };
 
 struct mcp251xfd_tx_ring {