From 812270e5445bd13859b70f9510e84068c6778333 Mon Sep 17 00:00:00 2001 From: Matt Kline Date: Mon, 16 Aug 2021 22:08:53 -0700 Subject: [PATCH] can: m_can: Batch FIFO writes during CAN transmit Give FIFO writes the same treatment as reads to avoid fixed costs of individual transfers on a slow bus (e.g., tcan4x5x). Link: https://lore.kernel.org/r/20210817050853.14875-4-matt@bitbashing.io Signed-off-by: Matt Kline Signed-off-by: Marc Kleine-Budde --- drivers/net/can/m_can/m_can.c | 61 ++++++++++++++++++------------------------- 1 file changed, 26 insertions(+), 35 deletions(-) diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c index fbd32b4..2470c47 100644 --- a/drivers/net/can/m_can/m_can.c +++ b/drivers/net/can/m_can/m_can.c @@ -279,7 +279,7 @@ enum m_can_reg { /* Message RAM Elements */ #define M_CAN_FIFO_ID 0x0 #define M_CAN_FIFO_DLC 0x4 -#define M_CAN_FIFO_DATA(n) (0x8 + ((n) << 2)) +#define M_CAN_FIFO_DATA 0x8 /* Rx Buffer Element */ /* R0 */ @@ -514,7 +514,7 @@ static int m_can_read_fifo(struct net_device *dev, u32 rxfs) if (fifo_header.dlc & RX_BUF_BRS) cf->flags |= CANFD_BRS; - err = m_can_fifo_read(cdev, fgi, M_CAN_FIFO_DATA(0), + err = m_can_fifo_read(cdev, fgi, M_CAN_FIFO_DATA, cf->data, DIV_ROUND_UP(cf->len, 4)); if (err) goto out_fail; @@ -1588,8 +1588,9 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev) struct canfd_frame *cf = (struct canfd_frame *)cdev->tx_skb->data; struct net_device *dev = cdev->net; struct sk_buff *skb = cdev->tx_skb; - u32 id, dlc, cccr, fdflags; - int i, err; + struct id_and_dlc fifo_header; + u32 cccr, fdflags; + int err; int putidx; cdev->tx_skb = NULL; @@ -1597,34 +1598,30 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev) /* Generate ID field for TX buffer Element */ /* Common to all supported M_CAN versions */ if (cf->can_id & CAN_EFF_FLAG) { - id = cf->can_id & CAN_EFF_MASK; - id |= TX_BUF_XTD; + fifo_header.id = cf->can_id & CAN_EFF_MASK; + fifo_header.id |= TX_BUF_XTD; } else { - id = ((cf->can_id & CAN_SFF_MASK) << 18); + fifo_header.id = ((cf->can_id & CAN_SFF_MASK) << 18); } if (cf->can_id & CAN_RTR_FLAG) - id |= TX_BUF_RTR; + fifo_header.id |= TX_BUF_RTR; if (cdev->version == 30) { netif_stop_queue(dev); - /* message ram configuration */ - err = m_can_fifo_write(cdev, 0, M_CAN_FIFO_ID, &id, 1); + fifo_header.dlc = can_fd_len2dlc(cf->len) << 16; + + /* Write the frame ID, DLC, and payload to the FIFO element. */ + err = m_can_fifo_write(cdev, 0, M_CAN_FIFO_ID, &fifo_header, 2); if (err) goto out_fail; - dlc = can_fd_len2dlc(cf->len) << 16; - err = m_can_fifo_write(cdev, 0, M_CAN_FIFO_DLC, &dlc, 1); + err = m_can_fifo_write(cdev, 0, M_CAN_FIFO_DATA, + cf->data, DIV_ROUND_UP(cf->len, 4)); if (err) goto out_fail; - for (i = 0; i < cf->len; i += 4) { - err = m_can_fifo_write(cdev, 0, M_CAN_FIFO_DATA(i / 4), cf->data + i, 1); - if (err) - goto out_fail; - } - can_put_echo_skb(skb, dev, 0, 0); if (cdev->can.ctrlmode & CAN_CTRLMODE_FD) { @@ -1667,10 +1664,11 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev) /* get put index for frame */ putidx = FIELD_GET(TXFQS_TFQPI_MASK, m_can_read(cdev, M_CAN_TXFQS)); - /* Write ID Field to FIFO Element */ - err = m_can_fifo_write(cdev, putidx, M_CAN_FIFO_ID, &id, 1); - if (err) - goto out_fail; + + /* Construct DLC Field, with CAN-FD configuration. + * Use the put index of the fifo as the message marker, + * used in the TX interrupt for sending the correct echo frame. + */ /* get CAN FD configuration of frame */ fdflags = 0; @@ -1680,24 +1678,17 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev) fdflags |= TX_BUF_BRS; } - /* Construct DLC Field. Also contains CAN-FD configuration - * use put index of fifo as message marker - * it is used in TX interrupt for - * sending the correct echo frame - */ - dlc = FIELD_PREP(TX_BUF_MM_MASK, putidx) | + fifo_header.dlc = FIELD_PREP(TX_BUF_MM_MASK, putidx) | FIELD_PREP(TX_BUF_DLC_MASK, can_fd_len2dlc(cf->len)) | fdflags | TX_BUF_EFC; - err = m_can_fifo_write(cdev, putidx, M_CAN_FIFO_DLC, &dlc, 1); + err = m_can_fifo_write(cdev, putidx, M_CAN_FIFO_ID, &fifo_header, 2); if (err) goto out_fail; - for (i = 0; i < cf->len; i += 4) { - err = m_can_fifo_write(cdev, putidx, M_CAN_FIFO_DATA(i / 4), - cf->data + i, 1); - if (err) - goto out_fail; - } + err = m_can_fifo_write(cdev, putidx, M_CAN_FIFO_DATA, + cf->data, DIV_ROUND_UP(cf->len, 4)); + if (err) + goto out_fail; /* Push loopback echo. * Will be looped back on TX interrupt based on message marker -- 2.7.4