From patchwork Wed Aug 19 06:55:50 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11722777 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id EE536618 for ; Wed, 19 Aug 2020 06:58:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C1EA7207FF for ; Wed, 19 Aug 2020 06:58:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="YH1vT2vq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728046AbgHSG57 (ORCPT ); Wed, 19 Aug 2020 02:57:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36862 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728068AbgHSG5v (ORCPT ); Wed, 19 Aug 2020 02:57:51 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 686E9C061389; Tue, 18 Aug 2020 23:57:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=EVErLVnSm6xDRGXKlec15d9C+2x1SE2cMBEl8na4gyI=; b=YH1vT2vqbroAI7tWxwF1l4qzHB D+Ix1eFFcW9uAkmmJy4zI/C6oAh2vLb94DyuUdLxe5tqjPqlCrcTaqshMieySvhtKNH7KUn/RLNIQ ycCZRO3sfH70CL8z3ys27iIDONZZJttrQLNqaYPnCLDsBSHTCfxGC9JtxUGhuw46QKJM7uCusR/jW ENHeTSJmFPyQ6rIMd1AiTRk14IZrs2a3AakwVGE+uY6KzKoQZBXFxlGfZy43I6dPa5H+s3BDRf8p1 Bufb4c9jPtmqQD4R1ZHqtRH/4J0u6rxqJby9Ir4tUT35WNtrJHCg9muNdnxhO37F9PxQgjgQmLbbV R7Xq6FZw==; Received: from [2001:4bb8:198:f3b2:86b6:2277:f429:37a1] (helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1k8I1g-0008Vm-R4; Wed, 19 Aug 2020 06:56:50 +0000 From: Christoph Hellwig To: Mauro Carvalho Chehab , Thomas Bogendoerfer , "James E.J. Bottomley" , Joonyoung Shim , Seung-Woo Kim , Kyungmin Park , Ben Skeggs , Pawel Osciak , Marek Szyprowski , Matt Porter , iommu@lists.linux-foundation.org Cc: Tom Lendacky , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-samsung-soc@vger.kernel.org, nouveau@lists.freedesktop.org, netdev@vger.kernel.org, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, linux-mm@kvack.org, alsa-devel@alsa-project.org Subject: [PATCH 23/28] lib82596: convert from dma_cache_sync to dma_sync_single_for_device Date: Wed, 19 Aug 2020 08:55:50 +0200 Message-Id: <20200819065555.1802761-24-hch@lst.de> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200819065555.1802761-1-hch@lst.de> References: <20200819065555.1802761-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-samsung-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-samsung-soc@vger.kernel.org Use the proper modern API to transfer cache ownership for incoherent DMA. Note that this moves the DMA helpers to the main lib82596.c file, so that they can use virt_to_dma. Signed-off-by: Christoph Hellwig --- drivers/net/ethernet/i825xx/lasi_82596.c | 11 +-- drivers/net/ethernet/i825xx/lib82596.c | 114 ++++++++++++++--------- drivers/net/ethernet/i825xx/sni_82596.c | 4 - 3 files changed, 73 insertions(+), 56 deletions(-) diff --git a/drivers/net/ethernet/i825xx/lasi_82596.c b/drivers/net/ethernet/i825xx/lasi_82596.c index 0c493b7237a910..d13b610935bcf3 100644 --- a/drivers/net/ethernet/i825xx/lasi_82596.c +++ b/drivers/net/ethernet/i825xx/lasi_82596.c @@ -96,21 +96,14 @@ #define OPT_SWAP_PORT 0x0001 /* Need to wordswp on the MPU port */ -#define DMA_WBACK(ndev, addr, len) \ - do { dma_cache_sync((ndev)->dev.parent, (void *)addr, len, DMA_TO_DEVICE); } while (0) - -#define DMA_INV(ndev, addr, len) \ - do { dma_cache_sync((ndev)->dev.parent, (void *)addr, len, DMA_FROM_DEVICE); } while (0) - -#define DMA_WBACK_INV(ndev, addr, len) \ - do { dma_cache_sync((ndev)->dev.parent, (void *)addr, len, DMA_BIDIRECTIONAL); } while (0) - #define SYSBUS 0x0000006c /* big endian CPU, 82596 "big" endian mode */ #define SWAP32(x) (((u32)(x)<<16) | ((((u32)(x)))>>16)) #define SWAP16(x) (x) +#define NONCOHERENT_DMA 1 + #include "lib82596.c" MODULE_AUTHOR("Richard Hirst"); diff --git a/drivers/net/ethernet/i825xx/lib82596.c b/drivers/net/ethernet/i825xx/lib82596.c index b4e4b3eb5758b5..ca2fb303fcc6f6 100644 --- a/drivers/net/ethernet/i825xx/lib82596.c +++ b/drivers/net/ethernet/i825xx/lib82596.c @@ -365,13 +365,44 @@ static int max_cmd_backlog = TX_RING_SIZE-1; static void i596_poll_controller(struct net_device *dev); #endif +static inline dma_addr_t virt_to_dma(struct i596_private *lp, volatile void *v) +{ + return lp->dma_addr + ((unsigned long)v - (unsigned long)lp->dma); +} + +#ifdef NONCOHERENT_DMA +static inline void dma_sync_dev(struct net_device *ndev, volatile void *addr, + size_t len) +{ + dma_sync_single_for_device(ndev->dev.parent, + virt_to_dma(netdev_priv(ndev), addr), len, + DMA_BIDIRECTIONAL); +} + +static inline void dma_sync_cpu(struct net_device *ndev, volatile void *addr, + size_t len) +{ + dma_sync_single_for_cpu(ndev->dev.parent, + virt_to_dma(netdev_priv(ndev), addr), len, + DMA_BIDIRECTIONAL); +} +#else +static inline void dma_sync_dev(struct net_device *ndev, volatile void *addr, + size_t len) +{ +} +static inline void dma_sync_cpu(struct net_device *ndev, volatile void *addr, + size_t len) +{ +} +#endif /* NONCOHERENT_DMA */ static inline int wait_istat(struct net_device *dev, struct i596_dma *dma, int delcnt, char *str) { - DMA_INV(dev, &(dma->iscp), sizeof(struct i596_iscp)); + dma_sync_cpu(dev, &(dma->iscp), sizeof(struct i596_iscp)); while (--delcnt && dma->iscp.stat) { udelay(10); - DMA_INV(dev, &(dma->iscp), sizeof(struct i596_iscp)); + dma_sync_cpu(dev, &(dma->iscp), sizeof(struct i596_iscp)); } if (!delcnt) { printk(KERN_ERR "%s: %s, iscp.stat %04x, didn't clear\n", @@ -384,10 +415,10 @@ static inline int wait_istat(struct net_device *dev, struct i596_dma *dma, int d static inline int wait_cmd(struct net_device *dev, struct i596_dma *dma, int delcnt, char *str) { - DMA_INV(dev, &(dma->scb), sizeof(struct i596_scb)); + dma_sync_cpu(dev, &(dma->scb), sizeof(struct i596_scb)); while (--delcnt && dma->scb.command) { udelay(10); - DMA_INV(dev, &(dma->scb), sizeof(struct i596_scb)); + dma_sync_cpu(dev, &(dma->scb), sizeof(struct i596_scb)); } if (!delcnt) { printk(KERN_ERR "%s: %s, status %4.4x, cmd %4.4x.\n", @@ -451,12 +482,9 @@ static void i596_display_data(struct net_device *dev) SWAP32(rbd->b_data), SWAP16(rbd->size)); rbd = rbd->v_next; } while (rbd != lp->rbd_head); - DMA_INV(dev, dma, sizeof(struct i596_dma)); + dma_sync_cpu(dev, dma, sizeof(struct i596_dma)); } - -#define virt_to_dma(lp, v) ((lp)->dma_addr + (dma_addr_t)((unsigned long)(v)-(unsigned long)((lp)->dma))) - static inline int init_rx_bufs(struct net_device *dev) { struct i596_private *lp = netdev_priv(dev); @@ -508,7 +536,7 @@ static inline int init_rx_bufs(struct net_device *dev) rfd->b_next = SWAP32(virt_to_dma(lp, dma->rfds)); rfd->cmd = SWAP16(CMD_EOL|CMD_FLEX); - DMA_WBACK_INV(dev, dma, sizeof(struct i596_dma)); + dma_sync_dev(dev, dma, sizeof(struct i596_dma)); return 0; } @@ -547,7 +575,7 @@ static void rebuild_rx_bufs(struct net_device *dev) lp->rbd_head = dma->rbds; dma->rfds[0].rbd = SWAP32(virt_to_dma(lp, dma->rbds)); - DMA_WBACK_INV(dev, dma, sizeof(struct i596_dma)); + dma_sync_dev(dev, dma, sizeof(struct i596_dma)); } @@ -575,9 +603,9 @@ static int init_i596_mem(struct net_device *dev) DEB(DEB_INIT, printk(KERN_DEBUG "%s: starting i82596.\n", dev->name)); - DMA_WBACK(dev, &(dma->scp), sizeof(struct i596_scp)); - DMA_WBACK(dev, &(dma->iscp), sizeof(struct i596_iscp)); - DMA_WBACK(dev, &(dma->scb), sizeof(struct i596_scb)); + dma_sync_dev(dev, &(dma->scp), sizeof(struct i596_scp)); + dma_sync_dev(dev, &(dma->iscp), sizeof(struct i596_iscp)); + dma_sync_dev(dev, &(dma->scb), sizeof(struct i596_scb)); mpu_port(dev, PORT_ALTSCP, virt_to_dma(lp, &dma->scp)); ca(dev); @@ -596,24 +624,24 @@ static int init_i596_mem(struct net_device *dev) rebuild_rx_bufs(dev); dma->scb.command = 0; - DMA_WBACK(dev, &(dma->scb), sizeof(struct i596_scb)); + dma_sync_dev(dev, &(dma->scb), sizeof(struct i596_scb)); DEB(DEB_INIT, printk(KERN_DEBUG "%s: queuing CmdConfigure\n", dev->name)); memcpy(dma->cf_cmd.i596_config, init_setup, 14); dma->cf_cmd.cmd.command = SWAP16(CmdConfigure); - DMA_WBACK(dev, &(dma->cf_cmd), sizeof(struct cf_cmd)); + dma_sync_dev(dev, &(dma->cf_cmd), sizeof(struct cf_cmd)); i596_add_cmd(dev, &dma->cf_cmd.cmd); DEB(DEB_INIT, printk(KERN_DEBUG "%s: queuing CmdSASetup\n", dev->name)); memcpy(dma->sa_cmd.eth_addr, dev->dev_addr, ETH_ALEN); dma->sa_cmd.cmd.command = SWAP16(CmdSASetup); - DMA_WBACK(dev, &(dma->sa_cmd), sizeof(struct sa_cmd)); + dma_sync_dev(dev, &(dma->sa_cmd), sizeof(struct sa_cmd)); i596_add_cmd(dev, &dma->sa_cmd.cmd); DEB(DEB_INIT, printk(KERN_DEBUG "%s: queuing CmdTDR\n", dev->name)); dma->tdr_cmd.cmd.command = SWAP16(CmdTDR); - DMA_WBACK(dev, &(dma->tdr_cmd), sizeof(struct tdr_cmd)); + dma_sync_dev(dev, &(dma->tdr_cmd), sizeof(struct tdr_cmd)); i596_add_cmd(dev, &dma->tdr_cmd.cmd); spin_lock_irqsave (&lp->lock, flags); @@ -625,7 +653,7 @@ static int init_i596_mem(struct net_device *dev) DEB(DEB_INIT, printk(KERN_DEBUG "%s: Issuing RX_START\n", dev->name)); dma->scb.command = SWAP16(RX_START); dma->scb.rfd = SWAP32(virt_to_dma(lp, dma->rfds)); - DMA_WBACK(dev, &(dma->scb), sizeof(struct i596_scb)); + dma_sync_dev(dev, &(dma->scb), sizeof(struct i596_scb)); ca(dev); @@ -659,13 +687,13 @@ static inline int i596_rx(struct net_device *dev) rfd = lp->rfd_head; /* Ref next frame to check */ - DMA_INV(dev, rfd, sizeof(struct i596_rfd)); + dma_sync_cpu(dev, rfd, sizeof(struct i596_rfd)); while (rfd->stat & SWAP16(STAT_C)) { /* Loop while complete frames */ if (rfd->rbd == I596_NULL) rbd = NULL; else if (rfd->rbd == lp->rbd_head->b_addr) { rbd = lp->rbd_head; - DMA_INV(dev, rbd, sizeof(struct i596_rbd)); + dma_sync_cpu(dev, rbd, sizeof(struct i596_rbd)); } else { printk(KERN_ERR "%s: rbd chain broken!\n", dev->name); /* XXX Now what? */ @@ -713,7 +741,7 @@ static inline int i596_rx(struct net_device *dev) DMA_FROM_DEVICE); rbd->v_data = newskb->data; rbd->b_data = SWAP32(dma_addr); - DMA_WBACK_INV(dev, rbd, sizeof(struct i596_rbd)); + dma_sync_dev(dev, rbd, sizeof(struct i596_rbd)); } else { skb = netdev_alloc_skb_ip_align(dev, pkt_len); } @@ -765,7 +793,7 @@ static inline int i596_rx(struct net_device *dev) if (rbd != NULL && (rbd->count & SWAP16(0x4000))) { rbd->count = 0; lp->rbd_head = rbd->v_next; - DMA_WBACK_INV(dev, rbd, sizeof(struct i596_rbd)); + dma_sync_dev(dev, rbd, sizeof(struct i596_rbd)); } /* Tidy the frame descriptor, marking it as end of list */ @@ -779,14 +807,14 @@ static inline int i596_rx(struct net_device *dev) lp->dma->scb.rfd = rfd->b_next; lp->rfd_head = rfd->v_next; - DMA_WBACK_INV(dev, rfd, sizeof(struct i596_rfd)); + dma_sync_dev(dev, rfd, sizeof(struct i596_rfd)); /* Remove end-of-list from old end descriptor */ rfd->v_prev->cmd = SWAP16(CMD_FLEX); - DMA_WBACK_INV(dev, rfd->v_prev, sizeof(struct i596_rfd)); + dma_sync_dev(dev, rfd->v_prev, sizeof(struct i596_rfd)); rfd = lp->rfd_head; - DMA_INV(dev, rfd, sizeof(struct i596_rfd)); + dma_sync_cpu(dev, rfd, sizeof(struct i596_rfd)); } DEB(DEB_RXFRAME, printk(KERN_DEBUG "frames %d\n", frames)); @@ -827,12 +855,12 @@ static inline void i596_cleanup_cmd(struct net_device *dev, struct i596_private ptr->v_next = NULL; ptr->b_next = I596_NULL; } - DMA_WBACK_INV(dev, ptr, sizeof(struct i596_cmd)); + dma_sync_dev(dev, ptr, sizeof(struct i596_cmd)); } wait_cmd(dev, lp->dma, 100, "i596_cleanup_cmd timed out"); lp->dma->scb.cmd = I596_NULL; - DMA_WBACK(dev, &(lp->dma->scb), sizeof(struct i596_scb)); + dma_sync_dev(dev, &(lp->dma->scb), sizeof(struct i596_scb)); } @@ -850,7 +878,7 @@ static inline void i596_reset(struct net_device *dev, struct i596_private *lp) /* FIXME: this command might cause an lpmc */ lp->dma->scb.command = SWAP16(CUC_ABORT | RX_ABORT); - DMA_WBACK(dev, &(lp->dma->scb), sizeof(struct i596_scb)); + dma_sync_dev(dev, &(lp->dma->scb), sizeof(struct i596_scb)); ca(dev); /* wait for shutdown */ @@ -878,20 +906,20 @@ static void i596_add_cmd(struct net_device *dev, struct i596_cmd *cmd) cmd->command |= SWAP16(CMD_EOL | CMD_INTR); cmd->v_next = NULL; cmd->b_next = I596_NULL; - DMA_WBACK(dev, cmd, sizeof(struct i596_cmd)); + dma_sync_dev(dev, cmd, sizeof(struct i596_cmd)); spin_lock_irqsave (&lp->lock, flags); if (lp->cmd_head != NULL) { lp->cmd_tail->v_next = cmd; lp->cmd_tail->b_next = SWAP32(virt_to_dma(lp, &cmd->status)); - DMA_WBACK(dev, lp->cmd_tail, sizeof(struct i596_cmd)); + dma_sync_dev(dev, lp->cmd_tail, sizeof(struct i596_cmd)); } else { lp->cmd_head = cmd; wait_cmd(dev, dma, 100, "i596_add_cmd timed out"); dma->scb.cmd = SWAP32(virt_to_dma(lp, &cmd->status)); dma->scb.command = SWAP16(CUC_START); - DMA_WBACK(dev, &(dma->scb), sizeof(struct i596_scb)); + dma_sync_dev(dev, &(dma->scb), sizeof(struct i596_scb)); ca(dev); } lp->cmd_tail = cmd; @@ -956,7 +984,7 @@ static void i596_tx_timeout (struct net_device *dev, unsigned int txqueue) /* Issue a channel attention signal */ DEB(DEB_ERRORS, printk(KERN_DEBUG "Kicking board.\n")); lp->dma->scb.command = SWAP16(CUC_START | RX_START); - DMA_WBACK_INV(dev, &(lp->dma->scb), sizeof(struct i596_scb)); + dma_sync_dev(dev, &(lp->dma->scb), sizeof(struct i596_scb)); ca (dev); lp->last_restart = dev->stats.tx_packets; } @@ -1014,8 +1042,8 @@ static netdev_tx_t i596_start_xmit(struct sk_buff *skb, struct net_device *dev) tbd->data = SWAP32(tx_cmd->dma_addr); DEB(DEB_TXADDR, print_eth(skb->data, "tx-queued")); - DMA_WBACK_INV(dev, tx_cmd, sizeof(struct tx_cmd)); - DMA_WBACK_INV(dev, tbd, sizeof(struct i596_tbd)); + dma_sync_dev(dev, tx_cmd, sizeof(struct tx_cmd)); + dma_sync_dev(dev, tbd, sizeof(struct i596_tbd)); i596_add_cmd(dev, &tx_cmd->cmd); dev->stats.tx_packets++; @@ -1071,7 +1099,7 @@ static int i82596_probe(struct net_device *dev) lp->dma->scb.rfd = I596_NULL; spin_lock_init(&lp->lock); - DMA_WBACK_INV(dev, lp->dma, sizeof(struct i596_dma)); + dma_sync_dev(dev, lp->dma, sizeof(struct i596_dma)); ret = register_netdev(dev); if (ret) @@ -1141,7 +1169,7 @@ static irqreturn_t i596_interrupt(int irq, void *dev_id) dev->name, status & 0x0700)); while (lp->cmd_head != NULL) { - DMA_INV(dev, lp->cmd_head, sizeof(struct i596_cmd)); + dma_sync_cpu(dev, lp->cmd_head, sizeof(struct i596_cmd)); if (!(lp->cmd_head->status & SWAP16(STAT_C))) break; @@ -1223,7 +1251,7 @@ static irqreturn_t i596_interrupt(int irq, void *dev_id) } ptr->v_next = NULL; ptr->b_next = I596_NULL; - DMA_WBACK(dev, ptr, sizeof(struct i596_cmd)); + dma_sync_dev(dev, ptr, sizeof(struct i596_cmd)); lp->last_cmd = jiffies; } @@ -1237,13 +1265,13 @@ static irqreturn_t i596_interrupt(int irq, void *dev_id) ptr->command &= SWAP16(0x1fff); ptr = ptr->v_next; - DMA_WBACK_INV(dev, prev, sizeof(struct i596_cmd)); + dma_sync_dev(dev, prev, sizeof(struct i596_cmd)); } if (lp->cmd_head != NULL) ack_cmd |= CUC_START; dma->scb.cmd = SWAP32(virt_to_dma(lp, &lp->cmd_head->status)); - DMA_WBACK_INV(dev, &dma->scb, sizeof(struct i596_scb)); + dma_sync_dev(dev, &dma->scb, sizeof(struct i596_scb)); } if ((status & 0x1000) || (status & 0x4000)) { if ((status & 0x4000)) @@ -1268,7 +1296,7 @@ static irqreturn_t i596_interrupt(int irq, void *dev_id) } wait_cmd(dev, dma, 100, "i596 interrupt, timeout"); dma->scb.command = SWAP16(ack_cmd); - DMA_WBACK(dev, &dma->scb, sizeof(struct i596_scb)); + dma_sync_dev(dev, &dma->scb, sizeof(struct i596_scb)); /* DANGER: I suspect that some kind of interrupt acknowledgement aside from acking the 82596 might be needed @@ -1299,7 +1327,7 @@ static int i596_close(struct net_device *dev) wait_cmd(dev, lp->dma, 100, "close1 timed out"); lp->dma->scb.command = SWAP16(CUC_ABORT | RX_ABORT); - DMA_WBACK(dev, &lp->dma->scb, sizeof(struct i596_scb)); + dma_sync_dev(dev, &lp->dma->scb, sizeof(struct i596_scb)); ca(dev); @@ -1358,7 +1386,7 @@ static void set_multicast_list(struct net_device *dev) dev->name); else { dma->cf_cmd.cmd.command = SWAP16(CmdConfigure); - DMA_WBACK_INV(dev, &dma->cf_cmd, sizeof(struct cf_cmd)); + dma_sync_dev(dev, &dma->cf_cmd, sizeof(struct cf_cmd)); i596_add_cmd(dev, &dma->cf_cmd.cmd); } } @@ -1390,7 +1418,7 @@ static void set_multicast_list(struct net_device *dev) dev->name, cp)); cp += ETH_ALEN; } - DMA_WBACK_INV(dev, &dma->mc_cmd, sizeof(struct mc_cmd)); + dma_sync_dev(dev, &dma->mc_cmd, sizeof(struct mc_cmd)); i596_add_cmd(dev, &cmd->cmd); } } diff --git a/drivers/net/ethernet/i825xx/sni_82596.c b/drivers/net/ethernet/i825xx/sni_82596.c index e80e790ffbd4d4..507d60cd6f9b33 100644 --- a/drivers/net/ethernet/i825xx/sni_82596.c +++ b/drivers/net/ethernet/i825xx/sni_82596.c @@ -24,10 +24,6 @@ static const char sni_82596_string[] = "snirm_82596"; -#define DMA_WBACK(priv, addr, len) do { } while (0) -#define DMA_INV(priv, addr, len) do { } while (0) -#define DMA_WBACK_INV(priv, addr, len) do { } while (0) - #define SYSBUS 0x00004400 /* big endian CPU, 82596 little endian */