From patchwork Fri Jul 16 16:56:22 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dario Binacchi X-Patchwork-Id: 12382545 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1497BC12002 for ; Fri, 16 Jul 2021 16:57:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ECD6E61396 for ; Fri, 16 Jul 2021 16:57:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230466AbhGPRAQ (ORCPT ); Fri, 16 Jul 2021 13:00:16 -0400 Received: from smtp-33-i2.italiaonline.it ([213.209.12.33]:37885 "EHLO libero.it" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S230208AbhGPQ76 (ORCPT ); Fri, 16 Jul 2021 12:59:58 -0400 Received: from passgat-Modern-14-A10M.homenet.telecomitalia.it ([79.54.92.92]) by smtp-33.iol.local with ESMTPA id 4R8tmKNNmS6GM4R90mO7bh; Fri, 16 Jul 2021 18:56:58 +0200 x-libjamoibt: 1601 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=libero.it; s=s2021; t=1626454618; bh=VGNCFLBzeyw84IVyEb6PZZrx3WMwI604pwR2tdhmc4g=; h=From; b=UBk+z1nm9wR4TYy2TKzrMrAwrjUSmOVulhehuJc3Jkfzq06N5YCLfBzFB+3vZv2Ia co5t4rQViC16HA1IRTs2Bt4Yki1S7XO1GXC6vG7d6BLSMZeq2zl1fmbptSUjG6faYi IIQPHMem+ZXDn2EB74RTCB2hSQkVavCsZFuCoWOD0A+wAHET2taVxZmUC2utDTeAwA HV8C9KDiMBuFwVrxWvP+Fw9Xi6xFx2MVMmnyduqHtCdhZmL3g/jJCJIxWEMUV0+vHU lpeYWfYnuJAy8dN8je6XiIcOkGgOBIhgaKnJb6S/ArJP5Q30GVXYUQzBOQuOtS6O5i d3dmPaNgpkLrg== X-CNFS-Analysis: v=2.4 cv=AcF0o1bG c=1 sm=1 tr=0 ts=60f1ba5a cx=a_exe a=eKwsI+FXzXP/Nc4oRbpalQ==:117 a=eKwsI+FXzXP/Nc4oRbpalQ==:17 a=VwQbUJbxAAAA:8 a=83yiEfbaggHBMMd4CMwA:9 a=TlxWwjO5pACKU3_K:21 a=9s_oUIA50SGwrPgz:21 a=AjGcO6oz07-iQ99wixmX:22 From: Dario Binacchi To: linux-kernel@vger.kernel.org Cc: Gianluca Falavigna , Dario Binacchi , Andrew Lunn , "David S. Miller" , Jakub Kicinski , Marc Kleine-Budde , Oliver Hartkopp , Vincent Mailhol , Wolfgang Grandegger , linux-can@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH 3/4] can: c_can: support tx ring algorithm Date: Fri, 16 Jul 2021 18:56:22 +0200 Message-Id: <20210716165623.19677-4-dariobin@libero.it> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210716165623.19677-1-dariobin@libero.it> References: <20210716165623.19677-1-dariobin@libero.it> X-CMAE-Envelope: MS4xfLH9hcar4n2Z0lDfTRw6KsDOa/8RUbDd3uxDk+x6+jx+2/mqp6ypsPo8YZHLpIWU9dbXqEKenWUeixgw0FphysQXlC+rw8+nSjVW1UJdJgPNSwc6veNg 5sUZzzTTYd26HNcbs9fulOr5URgYfAQVDVmq1igHEyR94YHpY25DsrxOf5vR5PXH5BQvJu/QzohOnGEkrpcGdpiQ6jJZKF3N1yxyRTqRPvaGeuvcEPFDfLO5 cH4bIfuvHiuKmwbCc1Rm+XoPULxlyqDJ4IjHgHDlybQjPw/OF24GEB/sGNN069IEfEFhUj8OgN1vmfHnhhe6XrKFoLWBuapp+c3tW9Wv5aZGrkycmc1WZXDP di/E+GPp5trVFsnRIe4YKtJd9/8LXPCkcHnFVj5ufgEiqjIcAK/icBFezkPFCGsUj0XU/b7909HOrNFO+WHpU1LDY2xlVXpo1tpbGeKmAeFtexSWLDf7D5LH 9pG7CfqmNEPaIPvjl+iWhr8EU+8PvzZB5zssx8eDo3UK0r6dym+TyR7CEVnq9DrRZRaOFlyBfZ5VOPbnxyVW9qSyPUXNbEceKeBLzVrzCzb+nOAlMk8ueiNl 9V0= Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org The algorithm is already used successfully by other CAN drivers (e.g. mcp251xfd). Its implementation was kindly suggested to me by Marc Kleine-Budde following a patch I had previously submitted. You can find every detail at https://lore.kernel.org/patchwork/patch/1422929/. The idea is that after this patch, it will be easier to patch the driver to use the message object memory as a true FIFO. Suggested-by: Marc Kleine-Budde Signed-off-by: Dario Binacchi --- drivers/net/can/c_can/c_can.h | 19 ++++++- drivers/net/can/c_can/c_can_main.c | 81 +++++++++++++++++++++++------- 2 files changed, 82 insertions(+), 18 deletions(-) diff --git a/drivers/net/can/c_can/c_can.h b/drivers/net/can/c_can/c_can.h index 8f23e9c83c84..8fe7e2138620 100644 --- a/drivers/net/can/c_can/c_can.h +++ b/drivers/net/can/c_can/c_can.h @@ -176,6 +176,13 @@ struct c_can_raminit { bool needs_pulse; }; +/* c_can tx ring structure */ +struct c_can_tx_ring { + unsigned int head; + unsigned int tail; + unsigned int obj_num; +}; + /* c_can private data structure */ struct c_can_priv { struct can_priv can; /* must be the first member */ @@ -190,10 +197,10 @@ struct c_can_priv { unsigned int msg_obj_tx_first; unsigned int msg_obj_tx_last; u32 msg_obj_rx_mask; - atomic_t tx_active; atomic_t sie_pending; unsigned long tx_dir; int last_status; + struct c_can_tx_ring tx; u16 (*read_reg)(const struct c_can_priv *priv, enum reg index); void (*write_reg)(const struct c_can_priv *priv, enum reg index, u16 val); u32 (*read_reg32)(const struct c_can_priv *priv, enum reg index); @@ -219,4 +226,14 @@ int c_can_power_down(struct net_device *dev); void c_can_set_ethtool_ops(struct net_device *dev); +static inline u8 c_can_get_tx_head(const struct c_can_tx_ring *ring) +{ + return ring->head & (ring->obj_num - 1); +} + +static inline u8 c_can_get_tx_tail(const struct c_can_tx_ring *ring) +{ + return ring->tail & (ring->obj_num - 1); +} + #endif /* C_CAN_H */ diff --git a/drivers/net/can/c_can/c_can_main.c b/drivers/net/can/c_can/c_can_main.c index fec0e3416970..451ac9a9586a 100644 --- a/drivers/net/can/c_can/c_can_main.c +++ b/drivers/net/can/c_can/c_can_main.c @@ -427,24 +427,64 @@ static void c_can_setup_receive_object(struct net_device *dev, int iface, c_can_object_put(dev, iface, obj, IF_COMM_RCV_SETUP); } +static u8 c_can_get_tx_free(const struct c_can_tx_ring *ring) +{ + u8 head = c_can_get_tx_head(ring); + u8 tail = c_can_get_tx_tail(ring); + + /* This is not a FIFO. C/D_CAN sends out the buffers + * prioritized. The lowest buffer number wins. + */ + if (head < tail) + return 0; + + return ring->obj_num - head; +} + +static bool c_can_tx_busy(const struct c_can_priv *priv, + const struct c_can_tx_ring *tx_ring) +{ + if (c_can_get_tx_free(tx_ring) > 0) + return false; + + netif_stop_queue(priv->dev); + + /* Memory barrier before checking tx_free (head and tail) */ + smp_mb(); + + if (c_can_get_tx_free(tx_ring) == 0) { + netdev_dbg(priv->dev, + "Stopping tx-queue (tx_head=0x%08x, tx_tail=0x%08x, len=%d).\n", + tx_ring->head, tx_ring->tail, + tx_ring->head - tx_ring->tail); + return true; + } + + netif_start_queue(priv->dev); + return false; +} + static netdev_tx_t c_can_start_xmit(struct sk_buff *skb, struct net_device *dev) { struct can_frame *frame = (struct can_frame *)skb->data; struct c_can_priv *priv = netdev_priv(dev); + struct c_can_tx_ring *tx_ring = &priv->tx; u32 idx, obj; if (can_dropped_invalid_skb(dev, skb)) return NETDEV_TX_OK; - /* This is not a FIFO. C/D_CAN sends out the buffers - * prioritized. The lowest buffer number wins. - */ - idx = fls(atomic_read(&priv->tx_active)); - obj = idx + priv->msg_obj_tx_first; - /* If this is the last buffer, stop the xmit queue */ - if (idx == priv->msg_obj_tx_num - 1) + if (c_can_tx_busy(priv, tx_ring)) + return NETDEV_TX_BUSY; + + idx = c_can_get_tx_head(tx_ring); + tx_ring->head++; + if (c_can_get_tx_free(tx_ring) == 0) netif_stop_queue(dev); + + obj = idx + priv->msg_obj_tx_first; + /* Store the message in the interface so we can call * can_put_echo_skb(). We must do this before we enable * transmit as we might race against do_tx(). @@ -453,8 +493,6 @@ static netdev_tx_t c_can_start_xmit(struct sk_buff *skb, priv->dlc[idx] = frame->len; can_put_echo_skb(skb, dev, idx, 0); - /* Update the active bits */ - atomic_add(BIT(idx), &priv->tx_active); /* Start transmission */ c_can_object_put(dev, IF_TX, obj, IF_COMM_TX); @@ -567,6 +605,7 @@ static int c_can_software_reset(struct net_device *dev) static int c_can_chip_config(struct net_device *dev) { struct c_can_priv *priv = netdev_priv(dev); + struct c_can_tx_ring *tx_ring = &priv->tx; int err; err = c_can_software_reset(dev); @@ -598,7 +637,8 @@ static int c_can_chip_config(struct net_device *dev) priv->write_reg(priv, C_CAN_STS_REG, LEC_UNUSED); /* Clear all internal status */ - atomic_set(&priv->tx_active, 0); + tx_ring->head = 0; + tx_ring->tail = 0; priv->tx_dir = 0; /* set bittiming params */ @@ -696,14 +736,14 @@ static int c_can_get_berr_counter(const struct net_device *dev, static void c_can_do_tx(struct net_device *dev) { struct c_can_priv *priv = netdev_priv(dev); + struct c_can_tx_ring *tx_ring = &priv->tx; struct net_device_stats *stats = &dev->stats; - u32 idx, obj, pkts = 0, bytes = 0, pend, clr; + u32 idx, obj, pkts = 0, bytes = 0, pend; if (priv->msg_obj_tx_last > 32) pend = priv->read_reg32(priv, C_CAN_INTPND3_REG); else pend = priv->read_reg(priv, C_CAN_INTPND2_REG); - clr = pend; while ((idx = ffs(pend))) { idx--; @@ -723,11 +763,14 @@ static void c_can_do_tx(struct net_device *dev) if (!pkts) return; - /* Clear the bits in the tx_active mask */ - atomic_sub(clr, &priv->tx_active); - - if (clr & BIT(priv->msg_obj_tx_num - 1)) - netif_wake_queue(dev); + tx_ring->tail += pkts; + if (c_can_get_tx_free(tx_ring)) { + /* Make sure that anybody stopping the queue after + * this sees the new tx_ring->tail. + */ + smp_mb(); + netif_wake_queue(priv->dev); + } stats->tx_bytes += bytes; stats->tx_packets += pkts; @@ -1206,6 +1249,10 @@ struct net_device *alloc_c_can_dev(int msg_obj_num) priv->msg_obj_tx_last = priv->msg_obj_tx_first + priv->msg_obj_tx_num - 1; + priv->tx.head = 0; + priv->tx.tail = 0; + priv->tx.obj_num = msg_obj_tx_num; + netif_napi_add(dev, &priv->napi, c_can_poll, priv->msg_obj_rx_num); priv->dev = dev;