patch-2.1.97 linux/arch/ppc/8xx_io/enet.c

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diff -u --recursive --new-file v2.1.96/linux/arch/ppc/8xx_io/enet.c linux/arch/ppc/8xx_io/enet.c
@@ -0,0 +1,913 @@
+/*
+ * Ethernet driver for Motorola MPC8xx.
+ * Copyright (c) 1997 Dan Malek (dmalek@jlc.net)
+ *
+ * I copied the basic skeleton from the lance driver, because I did not
+ * know how to write the Linux driver, but I did know how the LANCE worked.
+ * This version of the driver is specific to the MBX implementation,
+ * since the board contains control registers external to the processor
+ * for the control of the MC68160 SIA/transceiver.  The MPC860 manual
+ * describes connections using the internal parallel port I/O.
+ *
+ * The MBX860 uses the CPM SCC1 serial port for the Ethernet interface.
+ * Buffer descriptors are kept in the CPM dual port RAM, and the frame
+ * buffers are in the host memory.
+ *
+ * Right now, I am very watseful with the buffers.  I allocate memory
+ * pages and then divide them into 2K frame buffers.  This way I know I
+ * have buffers large enough to hold one frame within one buffer descriptor.
+ * Once I get this working, I will use 64 or 128 byte CPM buffers, which
+ * will be much more memory efficient and will easily handle lots of
+ * small packets.
+ *
+ */
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/string.h>
+#include <linux/ptrace.h>
+#include <linux/errno.h>
+#include <linux/ioport.h>
+#include <linux/malloc.h>
+#include <linux/interrupt.h>
+#include <linux/pci.h>
+#include <linux/bios32.h>
+#include <linux/init.h>
+#include <asm/bitops.h>
+
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/skbuff.h>
+
+#include <asm/8xx_immap.h>
+#include <asm/pgtable.h>
+#include <asm/mbx.h>
+#include "commproc.h"
+#include <linux/delay.h>
+
+/*
+ *				Theory of Operation
+ *
+ * The MPC8xx CPM performs the Ethernet processing on SCC1.  It can use
+ * an aribtrary number of buffers on byte boundaries, but must have at
+ * least two receive buffers to prevent constand overrun conditions.
+ *
+ * The buffer descriptors are allocated from the CPM dual port memory
+ * with the data buffers allocated from host memory, just like all other
+ * serial communication protocols.  The host memory buffers are allocated
+ * from the free page pool, and then divided into smaller receive and
+ * transmit buffers.  The size of the buffers should be a power of two,
+ * since that nicely divides the page.  This creates a ring buffer
+ * structure similar to the LANCE and other controllers.
+ *
+ * Like the LANCE driver:
+ * The driver runs as two independent, single-threaded flows of control.  One
+ * is the send-packet routine, which enforces single-threaded use by the
+ * dev->tbusy flag.  The other thread is the interrupt handler, which is single
+ * threaded by the hardware and other software.
+ *
+ * The send packet thread has partial control over the Tx ring and 'dev->tbusy'
+ * flag.  It sets the tbusy flag whenever it's queuing a Tx packet. If the next
+ * queue slot is empty, it clears the tbusy flag when finished otherwise it sets
+ * the 'lp->tx_full' flag.
+ *
+ * The MBX has a control register external to the MPC8xx that has some
+ * control of the Ethernet interface.  Control Register 1 has the
+ * following format:
+ *	bit 0 - Set to enable Ethernet transceiver
+ *	bit 1 - Set to enable Ethernet internal loopback
+ *	bit 2 - Set to auto select AUI or TP port
+ *	bit 3 - if bit 2 is 0, set to select TP port
+ *	bit 4 - Set to disable full duplex (loopback)
+ *	bit 5 - Set to disable XCVR collision test
+ *	bit 6, 7 - Used for RS-232 control.
+ *
+ * EPPC-Bug sets this register to 0x98 for normal Ethernet operation,
+ * so we should not have to touch it.
+ *
+ * The following I/O is used by the MBX implementation of the MPC8xx to
+ * the MC68160 transceiver.  It DOES NOT exactly follow the cookbook
+ * example from the MPC860 manual.
+ *	Port A, 15 - SCC1 Ethernet Rx
+ *	Port A, 14 - SCC1 Ethernet Tx
+ *	Port A, 6 (CLK2) - SCC1 Ethernet Tx Clk
+ *	Port A, 4 (CLK4) - SCC1 Ethernet Rx Clk
+ *	Port C, 15 - SCC1 Ethernet Tx Enable
+ *	Port C, 11 - SCC1 Ethernet Collision
+ *	Port C, 10 - SCC1 Ethernet Rx Enable
+ */
+
+/* The number of Tx and Rx buffers.  These are allocated from the page
+ * pool.  The code may assume these are power of two, so it it best
+ * to keep them that size.
+ * We don't need to allocate pages for the transmitter.  We just use
+ * the skbuffer directly.
+ */
+#define CPM_ENET_RX_PAGES	4
+#define CPM_ENET_RX_FRSIZE	2048
+#define CPM_ENET_RX_FRPPG	(PAGE_SIZE / CPM_ENET_RX_FRSIZE)
+#define RX_RING_SIZE		(CPM_ENET_RX_FRPPG * CPM_ENET_RX_PAGES)
+#define TX_RING_SIZE		8	/* Must be power of two */
+#define TX_RING_MOD_MASK	7	/*   for this to work */
+
+/* The CPM stores dest/src/type, data, and checksum for receive packets.
+ */
+#define PKT_MAXBUF_SIZE		1518
+#define PKT_MINBUF_SIZE		64
+#define PKT_MAXBLR_SIZE		1520
+
+/* The CPM buffer descriptors track the ring buffers.  The rx_bd_base and
+ * tx_bd_base always point to the base of the buffer descriptors.  The
+ * cur_rx and cur_tx point to the currently available buffer.
+ * The dirty_tx tracks the current buffer that is being sent by the
+ * controller.  The cur_tx and dirty_tx are equal under both completely
+ * empty and completely full conditions.  The empty/ready indicator in
+ * the buffer descriptor determines the actual condition.
+ */
+struct cpm_enet_private {
+	/* The saved address of a sent-in-place packet/buffer, for skfree(). */
+	struct	sk_buff* tx_skbuff[TX_RING_SIZE];
+	ushort	skb_cur;
+	ushort	skb_dirty;
+
+	/* CPM dual port RAM relative addresses.
+	*/
+	cbd_t	*rx_bd_base;		/* Address of Rx and Tx buffers. */
+	cbd_t	*tx_bd_base;
+	cbd_t	*cur_rx, *cur_tx;		/* The next free ring entry */
+	cbd_t	*dirty_tx;	/* The ring entries to be free()ed. */
+	scc_t	*sccp;
+	struct	net_device_stats stats;
+	char	tx_full;
+	unsigned long lock;
+};
+
+static int cpm_enet_open(struct device *dev);
+static int cpm_enet_start_xmit(struct sk_buff *skb, struct device *dev);
+static int cpm_enet_rx(struct device *dev);
+static void cpm_enet_interrupt(void *dev_id);
+static int cpm_enet_close(struct device *dev);
+static struct net_device_stats *cpm_enet_get_stats(struct device *dev);
+static void set_multicast_list(struct device *dev);
+
+/* GET THIS FROM THE VPD!!!!
+*/
+static	ushort	my_enet_addr[] = { 0x0800, 0x3e26, 0x1559 };
+
+/* Initialize the CPM Ethernet on SCC1.  If EPPC-Bug loaded us, or performed
+ * some other network I/O, a whole bunch of this has already been set up.
+ * It is no big deal if we do it again, we just have to disable the
+ * transmit and receive to make sure we don't catch the CPM with some
+ * inconsistent control information.
+ */
+__initfunc(int cpm_enet_init(void))
+{
+	struct device *dev;
+	struct cpm_enet_private *cep;
+	int i, j;
+	unsigned char	*eap;
+	unsigned long	mem_addr;
+	pte_t		*pte;
+	volatile	cbd_t		*bdp;
+	volatile	cpm8xx_t	*cp;
+	volatile	scc_t		*sccp;
+	volatile	scc_enet_t	*ep;
+	volatile	immap_t		*immap;
+
+	cp = cpmp;	/* Get pointer to Communication Processor */
+
+	immap = (immap_t *)MBX_IMAP_ADDR;	/* and to internal registers */
+
+	/* Allocate some private information.
+	*/
+	cep = (struct cpm_enet_private *)kmalloc(sizeof(*cep), GFP_KERNEL);
+	memset(cep, 0, sizeof(*cep));
+
+	/* Create an Ethernet device instance.
+	*/
+	dev = init_etherdev(0, 0);
+
+	/* Get pointer to SCC1 area in parameter RAM.
+	*/
+	ep = (scc_enet_t *)(&cp->cp_dparam[PROFF_SCC1]);
+
+	/* And another to the SCC register area.
+	*/
+	sccp = (volatile scc_t *)(&cp->cp_scc[0]);
+	cep->sccp = (scc_t *)sccp;		/* Keep the pointer handy */
+
+	/* Disable receive and transmit in case EPPC-Bug started it.
+	*/
+	sccp->scc_gsmrl &= ~(SCC_GSMRL_ENR | SCC_GSMRL_ENT);
+
+	/* Cookbook style from the MPC860 manual.....
+	 * Not all of this is necessary if EPPC-Bug has initialized
+	 * the network.
+	 */
+
+	/* Configure port A pins for Txd and Rxd.
+	*/
+	immap->im_ioport.iop_papar |= (PA_ENET_RXD | PA_ENET_TXD);
+	immap->im_ioport.iop_padir &= ~(PA_ENET_RXD | PA_ENET_TXD);
+	immap->im_ioport.iop_paodr &= ~PA_ENET_TXD;
+
+	/* Configure port C pins to enable CLSN and RENA.
+	*/
+	immap->im_ioport.iop_pcpar &= ~(PC_ENET_CLSN | PC_ENET_RENA);
+	immap->im_ioport.iop_pcdir &= ~(PC_ENET_CLSN | PC_ENET_RENA);
+	immap->im_ioport.iop_pcso |= (PC_ENET_CLSN | PC_ENET_RENA);
+
+	/* Configure port A for TCLK and RCLK.
+	*/
+	immap->im_ioport.iop_papar |= (PA_ENET_TCLK | PA_ENET_RCLK);
+	immap->im_ioport.iop_padir &= ~(PA_ENET_TCLK | PA_ENET_RCLK);
+
+	/* Configure Serial Interface clock routing.
+	 * First, clear all SCC1 bits to zero, then set the ones we want.
+	 */
+	cp->cp_sicr &= ~SICR_ENET_MASK;
+	cp->cp_sicr |= SICR_ENET_CLKRT;
+
+	/* Manual says set SDDR, but I can't find anything with that
+	 * name.  I think it is a misprint, and should be SDCR.  This
+	 * has already been set by the communication processor initialization.
+	 */
+
+	/* Allocate space for the buffer descriptors in the DP ram.
+	 * These are relative offsets in the DP ram address space.
+	 * Initialize base addresses for the buffer descriptors.
+	 */
+	i = mbx_cpm_dpalloc(sizeof(cbd_t) * RX_RING_SIZE);
+	ep->sen_genscc.scc_rbase = i;
+	cep->rx_bd_base = (cbd_t *)&cp->cp_dpmem[i];
+
+	i = mbx_cpm_dpalloc(sizeof(cbd_t) * TX_RING_SIZE);
+	ep->sen_genscc.scc_tbase = i;
+	cep->tx_bd_base = (cbd_t *)&cp->cp_dpmem[i];
+
+	cep->dirty_tx = cep->cur_tx = cep->tx_bd_base;
+	cep->cur_rx = cep->rx_bd_base;
+
+	/* Issue init Rx BD command for SCC1.
+	 * Manual says to perform an Init Rx parameters here.  We have
+	 * to perform both Rx and Tx because the SCC may have been
+	 * already running.
+	 * In addition, we have to do it later because we don't yet have
+	 * all of the BD control/status set properly.
+	cp->cp_cpcr = mk_cr_cmd(CPM_CR_CH_SCC1, CPM_CR_INIT_RX) | CPM_CR_FLG;
+	while (cp->cp_cpcr & CPM_CR_FLG);
+	 */
+
+	/* Initialize function code registers for big-endian.
+	*/
+	ep->sen_genscc.scc_rfcr = SCC_EB;
+	ep->sen_genscc.scc_tfcr = SCC_EB;
+
+	/* Set maximum bytes per receive buffer.
+	 * This appears to be an Ethernet frame size, not the buffer
+	 * fragment size.  It must be a multiple of four.
+	 */
+	ep->sen_genscc.scc_mrblr = PKT_MAXBLR_SIZE;
+
+	/* Set CRC preset and mask.
+	*/
+	ep->sen_cpres = 0xffffffff;
+	ep->sen_cmask = 0xdebb20e3;
+
+	ep->sen_crcec = 0;	/* CRC Error counter */
+	ep->sen_alec = 0;	/* alignment error counter */
+	ep->sen_disfc = 0;	/* discard frame counter */
+
+	ep->sen_pads = 0x8888;	/* Tx short frame pad character */
+	ep->sen_retlim = 15;	/* Retry limit threshold */
+
+	ep->sen_maxflr = PKT_MAXBUF_SIZE;   /* maximum frame length register */
+	ep->sen_minflr = PKT_MINBUF_SIZE;  /* minimum frame length register */
+
+	ep->sen_maxd1 = PKT_MAXBUF_SIZE;	/* maximum DMA1 length */
+	ep->sen_maxd2 = PKT_MAXBUF_SIZE;	/* maximum DMA2 length */
+
+	/* Clear hash tables.
+	*/
+	ep->sen_gaddr1 = 0;
+	ep->sen_gaddr2 = 0;
+	ep->sen_gaddr3 = 0;
+	ep->sen_gaddr4 = 0;
+	ep->sen_iaddr1 = 0;
+	ep->sen_iaddr2 = 0;
+	ep->sen_iaddr3 = 0;
+	ep->sen_iaddr4 = 0;
+
+	/* Set Ethernet station address.  This must come from the
+	 * Vital Product Data (VPD) EEPROM.....as soon as I get the
+	 * I2C interface working.....
+	 *
+	 * Since we performed a diskless boot, the Ethernet controller
+	 * has been initialized and we copy the address out into our
+	 * own structure.
+	 */
+#ifdef notdef
+	ep->sen_paddrh = my_enet_addr[0];
+	ep->sen_paddrm = my_enet_addr[1];
+	ep->sen_paddrl = my_enet_addr[2];
+#else
+	eap = (unsigned char *)&(ep->sen_paddrh);
+	for (i=5; i>=0; i--)
+		dev->dev_addr[i] = *eap++;
+#endif
+
+	ep->sen_pper = 0;	/* 'cause the book says so */
+	ep->sen_taddrl = 0;	/* temp address (LSB) */
+	ep->sen_taddrm = 0;
+	ep->sen_taddrh = 0;	/* temp address (MSB) */
+
+	/* Now allocate the host memory pages and initialize the
+	 * buffer descriptors.
+	 */
+	bdp = cep->tx_bd_base;
+	for (i=0; i<TX_RING_SIZE; i++) {
+
+		/* Initialize the BD for every fragment in the page.
+		*/
+		bdp->cbd_sc = 0;
+		bdp->cbd_bufaddr = 0;
+		bdp++;
+	}
+
+	/* Set the last buffer to wrap.
+	*/
+	bdp--;
+	bdp->cbd_sc |= BD_SC_WRAP;
+
+	bdp = cep->rx_bd_base;
+	for (i=0; i<CPM_ENET_RX_PAGES; i++) {
+
+		/* Allocate a page.
+		*/
+		mem_addr = __get_free_page(GFP_KERNEL);
+
+		/* Make it uncached.
+		*/
+		pte = va_to_pte(&init_task, mem_addr);
+		pte_val(*pte) |= _PAGE_NO_CACHE;
+		flush_tlb_page(current->mm->mmap, mem_addr);
+
+		/* Initialize the BD for every fragment in the page.
+		*/
+		for (j=0; j<CPM_ENET_RX_FRPPG; j++) {
+			bdp->cbd_sc = BD_ENET_RX_EMPTY | BD_ENET_RX_INTR;
+			bdp->cbd_bufaddr = __pa(mem_addr);
+			mem_addr += CPM_ENET_RX_FRSIZE;
+			bdp++;
+		}
+	}
+
+	/* Set the last buffer to wrap.
+	*/
+	bdp--;
+	bdp->cbd_sc |= BD_SC_WRAP;
+
+	/* Let's re-initialize the channel now.  We have to do it later
+	 * than the manual describes because we have just now finished
+	 * the BD initialization.
+	 */
+	cp->cp_cpcr = mk_cr_cmd(CPM_CR_CH_SCC1, CPM_CR_INIT_TRX) | CPM_CR_FLG;
+	while (cp->cp_cpcr & CPM_CR_FLG);
+
+	cep->skb_cur = cep->skb_dirty = 0;
+
+	sccp->scc_scce = 0xffff;	/* Clear any pending events */
+
+	/* Enable interrupts for transmit error, complete frame
+	 * received, and any transmit buffer we have also set the
+	 * interrupt flag.
+	 */
+	sccp->scc_sccm = (SCCE_ENET_TXE | SCCE_ENET_RXF | SCCE_ENET_TXB);
+
+	/* Install our interrupt handler.
+	*/
+	cpm_install_handler(CPMVEC_SCC1, cpm_enet_interrupt, dev);
+
+	/* Set GSMR_H to enable all normal operating modes.
+	 * Set GSMR_L to enable Ethernet to MC68160.
+	 */
+	sccp->scc_gsmrh = 0;
+	sccp->scc_gsmrl = (SCC_GSMRL_TCI | SCC_GSMRL_TPL_48 | SCC_GSMRL_TPP_10 | SCC_GSMRL_MODE_ENET);
+
+	/* Set sync/delimiters.
+	*/
+	sccp->scc_dsr = 0xd555;
+
+	/* Set processing mode.  Use Ethernet CRC, catch broadcast, and
+	 * start frame search 22 bit times after RENA.
+	 */
+	sccp->scc_pmsr = (SCC_PMSR_ENCRC | SCC_PMSR_BRO | SCC_PMSR_NIB22);
+
+	/* It is now OK to enable the Ethernet transmitter.
+	*/
+	immap->im_ioport.iop_pcpar |= PC_ENET_TENA;
+	immap->im_ioport.iop_pcdir &= ~PC_ENET_TENA;
+
+	dev->base_addr = (unsigned long)ep;
+	dev->priv = cep;
+	dev->name = "CPM_ENET";
+
+	/* The CPM Ethernet specific entries in the device structure. */
+	dev->open = cpm_enet_open;
+	dev->hard_start_xmit = cpm_enet_start_xmit;
+	dev->stop = cpm_enet_close;
+	dev->get_stats = cpm_enet_get_stats;
+	dev->set_multicast_list = set_multicast_list;
+
+	/* And last, enable the transmit and receive processing.
+	*/
+	sccp->scc_gsmrl |= (SCC_GSMRL_ENR | SCC_GSMRL_ENT);
+
+	printk("CPM ENET Version 0.1, ");
+	for (i=0; i<5; i++)
+		printk("%02x:", dev->dev_addr[i]);
+	printk("%02x\n", dev->dev_addr[5]);
+
+	return 0;
+}
+
+static int
+cpm_enet_open(struct device *dev)
+{
+
+	/* I should reset the ring buffers here, but I don't yet know
+	 * a simple way to do that.
+	 */
+
+	dev->tbusy = 0;
+	dev->interrupt = 0;
+	dev->start = 1;
+
+	return 0;					/* Always succeed */
+}
+
+static int
+cpm_enet_start_xmit(struct sk_buff *skb, struct device *dev)
+{
+	struct cpm_enet_private *cep = (struct cpm_enet_private *)dev->priv;
+	volatile cbd_t	*bdp;
+	unsigned long flags;
+
+	/* Transmitter timeout, serious problems. */
+	if (dev->tbusy) {
+		int tickssofar = jiffies - dev->trans_start;
+		if (tickssofar < 20)
+			return 1;
+		printk("%s: transmit timed out.\n", dev->name);
+		cep->stats.tx_errors++;
+#ifndef final_version
+		{
+			int	i;
+			cbd_t	*bdp;
+			printk(" Ring data dump: cur_tx %x%s cur_rx %x.\n",
+				   cep->cur_tx, cep->tx_full ? " (full)" : "",
+				   cep->cur_rx);
+			bdp = cep->tx_bd_base;
+			for (i = 0 ; i < TX_RING_SIZE; i++)
+				printk("%04x %04x %08x\n",
+					bdp->cbd_sc,
+					bdp->cbd_datlen,
+					bdp->cbd_bufaddr);
+			bdp = cep->rx_bd_base;
+			for (i = 0 ; i < RX_RING_SIZE; i++)
+				printk("%04x %04x %08x\n",
+					bdp->cbd_sc,
+					bdp->cbd_datlen,
+					bdp->cbd_bufaddr);
+		}
+#endif
+
+		dev->tbusy=0;
+		dev->trans_start = jiffies;
+
+		return 0;
+	}
+
+	/* Block a timer-based transmit from overlapping.  This could better be
+	   done with atomic_swap(1, dev->tbusy), but set_bit() works as well. */
+	if (test_and_set_bit(0, (void*)&dev->tbusy) != 0) {
+		printk("%s: Transmitter access conflict.\n", dev->name);
+		return 1;
+	}
+
+	if (test_and_set_bit(0, (void*)&cep->lock) != 0) {
+		printk("%s: tx queue lock!.\n", dev->name);
+		/* don't clear dev->tbusy flag. */
+		return 1;
+	}
+
+	/* Fill in a Tx ring entry */
+	bdp = cep->cur_tx;
+
+#ifndef final_version
+	if (bdp->cbd_sc & BD_ENET_TX_READY) {
+		/* Ooops.  All transmit buffers are full.  Bail out.
+		 * This should not happen, since dev->tbusy should be set.
+		 */
+		printk("%s: tx queue full!.\n", dev->name);
+		cep->lock = 0;
+		return 1;
+	}
+#endif
+
+	/* Clear all of the status flags.
+	 */
+	bdp->cbd_sc &= ~BD_ENET_TX_STATS;
+
+	/* If the frame is short, tell CPM to pad it.
+	*/
+	if (skb->len <= ETH_ZLEN)
+		bdp->cbd_sc |= BD_ENET_TX_PAD;
+	else
+		bdp->cbd_sc &= ~BD_ENET_TX_PAD;
+
+	/* Set buffer length and buffer pointer.
+	*/
+	bdp->cbd_datlen = skb->len;
+	bdp->cbd_bufaddr = __pa(skb->data);
+
+	/* Save skb pointer.
+	*/
+	cep->tx_skbuff[cep->skb_cur] = skb;
+
+	cep->stats.tx_bytes += skb->len;
+	cep->skb_cur = (cep->skb_cur+1) & TX_RING_MOD_MASK;
+	
+	/* Push the data cache so the CPM does not get stale memory
+	 * data.
+	 */
+	/*flush_dcache_range(skb->data, skb->data + skb->len);*/
+
+	/* Send it on its way.  Tell CPM its ready, interrupt when done,
+	 * its the last BD of the frame, and to put the CRC on the end.
+	 */
+	bdp->cbd_sc |= (BD_ENET_TX_READY | BD_ENET_TX_INTR | BD_ENET_TX_LAST | BD_ENET_TX_TC);
+
+	dev->trans_start = jiffies;
+
+	/* If this was the last BD in the ring, start at the beginning again.
+	*/
+	if (bdp->cbd_sc & BD_ENET_TX_WRAP)
+		bdp = cep->tx_bd_base;
+	else
+		bdp++;
+
+	save_flags(flags);
+	cli();
+	cep->lock = 0;
+	if (bdp->cbd_sc & BD_ENET_TX_READY)
+		cep->tx_full = 1;
+	else
+		dev->tbusy=0;
+	restore_flags(flags);
+
+	cep->cur_tx = (cbd_t *)bdp;
+
+	return 0;
+}
+
+/* The interrupt handler.
+ * This is called from the CPM handler, not the MPC core interrupt.
+ */
+static void
+cpm_enet_interrupt(void *dev_id)
+{
+	struct	device *dev = dev_id;
+	struct	cpm_enet_private *cep;
+	volatile cbd_t	*bdp;
+	ushort	int_events;
+	int	must_restart;
+
+	cep = (struct cpm_enet_private *)dev->priv;
+	if (dev->interrupt)
+		printk("%s: Re-entering the interrupt handler.\n", dev->name);
+
+	dev->interrupt = 1;
+
+	/* Get the interrupt events that caused us to be here.
+	*/
+	int_events = cep->sccp->scc_scce;
+	must_restart = 0;
+
+	/* Handle receive event in its own function.
+	*/
+	if (int_events & SCCE_ENET_RXF)
+		cpm_enet_rx(dev_id);
+
+	/* Check for a transmit error.  The manual is a little unclear
+	 * about this, so the debug code until I get it figured out.  It
+	 * appears that if TXE is set, then TXB is not set.  However,
+	 * if carrier sense is lost during frame transmission, the TXE
+	 * bit is set, "and continues the buffer transmission normally."
+	 * I don't know if "normally" implies TXB is set when the buffer
+	 * descriptor is closed.....trial and error :-).
+	 */
+	if (int_events & SCCE_ENET_TXE) {
+
+		/* Transmission errors.
+		*/
+		bdp = cep->dirty_tx;
+#ifndef final_version
+		printk("CPM ENET xmit error %x\n", bdp->cbd_sc);
+		if (bdp->cbd_sc & BD_ENET_TX_READY)
+			printk("HEY! Enet xmit interrupt and TX_READY.\n");
+#endif
+		if (bdp->cbd_sc & BD_ENET_TX_HB)	/* No heartbeat */
+			cep->stats.tx_heartbeat_errors++;
+		if (bdp->cbd_sc & BD_ENET_TX_LC)	/* Late collision */
+			cep->stats.tx_window_errors++;
+		if (bdp->cbd_sc & BD_ENET_TX_RL)	/* Retrans limit */
+			cep->stats.tx_aborted_errors++;
+		if (bdp->cbd_sc & BD_ENET_TX_UN)	/* Underrun */
+			cep->stats.tx_fifo_errors++;
+		if (bdp->cbd_sc & BD_ENET_TX_CSL)	/* Carrier lost */
+			cep->stats.tx_carrier_errors++;
+
+		cep->stats.tx_errors++;
+
+		/* No heartbeat or Lost carrier are not really bad errors.
+		 * The others require a restart transmit command.
+		 */
+		if (bdp->cbd_sc &
+		    (BD_ENET_TX_LC | BD_ENET_TX_RL | BD_ENET_TX_UN))
+			must_restart = 1;
+	}
+
+	/* Transmit OK, or non-fatal error.  Update the buffer descriptors.
+	*/
+	if (int_events & (SCCE_ENET_TXE | SCCE_ENET_TXB)) {
+		cep->stats.tx_packets++;
+		bdp = cep->dirty_tx;
+#ifndef final_version
+		if (bdp->cbd_sc & BD_ENET_TX_READY)
+			printk("HEY! Enet xmit interrupt and TX_READY.\n");
+#endif
+		/* Deferred means some collisions occurred during transmit,
+		 * but we eventually sent the packet OK.
+		 */
+		if (bdp->cbd_sc & BD_ENET_TX_DEF)
+			cep->stats.collisions++;
+
+		/* Free the sk buffer associated with this last transmit.
+		*/
+		dev_kfree_skb(cep->tx_skbuff[cep->skb_dirty]/*, FREE_WRITE*/);
+		cep->skb_dirty = (cep->skb_dirty + 1) & TX_RING_MOD_MASK;
+
+		/* Update pointer to next buffer descriptor to be transmitted.
+		*/
+		if (bdp->cbd_sc & BD_ENET_TX_WRAP)
+			bdp = cep->tx_bd_base;
+		else
+			bdp++;
+
+		/* I don't know if we can be held off from processing these
+		 * interrupts for more than one frame time.  I really hope
+		 * not.  In such a case, we would now want to check the
+		 * currently available BD (cur_tx) and determine if any
+		 * buffers between the dirty_tx and cur_tx have also been
+		 * sent.  We would want to process anything in between that
+		 * does not have BD_ENET_TX_READY set.
+		 */
+
+		/* Since we have freed up a buffer, the ring is no longer
+		 * full.
+		 */
+		if (cep->tx_full && dev->tbusy) {
+			cep->tx_full = 0;
+			dev->tbusy = 0;
+			mark_bh(NET_BH);
+		}
+
+		cep->dirty_tx = (cbd_t *)bdp;
+	}
+
+	if (must_restart) {
+		volatile cpm8xx_t *cp;
+
+		/* Some transmit errors cause the transmitter to shut
+		 * down.  We now issue a restart transmit.  Since the
+		 * errors close the BD and update the pointers, the restart
+		 * _should_ pick up without having to reset any of our
+		 * pointers either.
+		 */
+		cp = cpmp;
+		cp->cp_cpcr =
+		    mk_cr_cmd(CPM_CR_CH_SCC1, CPM_CR_RESTART_TX) | CPM_CR_FLG;
+		while (cp->cp_cpcr & CPM_CR_FLG);
+	}
+
+	/* Check for receive busy, i.e. packets coming but no place to
+	 * put them.  This "can't happen" because the receive interrupt
+	 * is tossing previous frames.
+	 */
+	if (int_events & SCCE_ENET_BSY) {
+		cep->stats.rx_dropped++;
+		printk("CPM ENET: BSY can't happen.\n");
+	}
+
+	/* Write the SCC event register with the events we have handled
+	 * to clear them.  Maybe we should do this sooner?
+	 */
+	cep->sccp->scc_scce = int_events;
+
+	dev->interrupt = 0;
+
+	return;
+}
+
+/* During a receive, the cur_rx points to the current incoming buffer.
+ * When we update through the ring, if the next incoming buffer has
+ * not been given to the system, we just set the empty indicator,
+ * effectively tossing the packet.
+ */
+static int
+cpm_enet_rx(struct device *dev)
+{
+	struct	cpm_enet_private *cep;
+	volatile cbd_t	*bdp;
+	struct	sk_buff *skb;
+	ushort	pkt_len;
+
+	cep = (struct cpm_enet_private *)dev->priv;
+
+	/* First, grab all of the stats for the incoming packet.
+	 * These get messed up if we get called due to a busy condition.
+	 */
+	bdp = cep->cur_rx;
+
+for (;;) {
+	if (bdp->cbd_sc & BD_ENET_RX_EMPTY)
+		break;
+		
+#ifndef final_version
+	/* Since we have allocated space to hold a complete frame, both
+	 * the first and last indicators should be set.
+	 */
+	if ((bdp->cbd_sc & (BD_ENET_RX_FIRST | BD_ENET_RX_LAST)) !=
+		(BD_ENET_RX_FIRST | BD_ENET_RX_LAST))
+			printk("CPM ENET: rcv is not first+last\n");
+#endif
+
+	/* Frame too long or too short.
+	*/
+	if (bdp->cbd_sc & (BD_ENET_RX_LG | BD_ENET_RX_SH))
+		cep->stats.rx_length_errors++;
+	if (bdp->cbd_sc & BD_ENET_RX_NO)	/* Frame alignment */
+		cep->stats.rx_frame_errors++;
+	if (bdp->cbd_sc & BD_ENET_RX_CR)	/* CRC Error */
+		cep->stats.rx_crc_errors++;
+	if (bdp->cbd_sc & BD_ENET_RX_OV)	/* FIFO overrun */
+		cep->stats.rx_crc_errors++;
+
+	/* Report late collisions as a frame error.
+	 * On this error, the BD is closed, but we don't know what we
+	 * have in the buffer.  So, just drop this frame on the floor.
+	 */
+	if (bdp->cbd_sc & BD_ENET_RX_CL) {
+		cep->stats.rx_frame_errors++;
+	}
+	else {
+
+		/* Process the incoming frame.
+		*/
+		cep->stats.rx_packets++;
+		pkt_len = bdp->cbd_datlen;
+		cep->stats.rx_bytes += pkt_len;
+
+		/* This does 16 byte alignment, much more than we need.
+		*/
+		skb = dev_alloc_skb(pkt_len);
+
+		if (skb == NULL) {
+			printk("%s: Memory squeeze, dropping packet.\n", dev->name);
+			cep->stats.rx_dropped++;
+		}
+		else {
+			skb->dev = dev;
+			skb_put(skb,pkt_len);	/* Make room */
+			eth_copy_and_sum(skb,
+				(unsigned char *)__va(bdp->cbd_bufaddr),
+				pkt_len, 0);
+			skb->protocol=eth_type_trans(skb,dev);
+			netif_rx(skb);
+		}
+	}
+
+	/* Clear the status flags for this buffer.
+	*/
+	bdp->cbd_sc &= ~BD_ENET_RX_STATS;
+
+	/* Mark the buffer empty.
+	*/
+	bdp->cbd_sc |= BD_ENET_RX_EMPTY;
+
+	/* Update BD pointer to next entry.
+	*/
+	if (bdp->cbd_sc & BD_ENET_RX_WRAP)
+		bdp = cep->rx_bd_base;
+	else
+		bdp++;
+
+   }
+	cep->cur_rx = (cbd_t *)bdp;
+
+	return 0;
+}
+
+static int
+cpm_enet_close(struct device *dev)
+{
+	/* Don't know what to do yet.
+	*/
+
+	return 0;
+}
+
+static struct net_device_stats *cpm_enet_get_stats(struct device *dev)
+{
+	struct cpm_enet_private *cep = (struct cpm_enet_private *)dev->priv;
+
+	return &cep->stats;
+}
+
+/* Set or clear the multicast filter for this adaptor.
+ * Skeleton taken from sunlance driver.
+ * The CPM Ethernet implementation allows Multicast as well as individual
+ * MAC address filtering.  Some of the drivers check to make sure it is
+ * a group multicast address, and discard those that are not.  I guess I
+ * will do the same for now, but just remove the test if you want
+ * individual filtering as well (do the upper net layers want or support
+ * this kind of feature?).
+ */
+
+static void set_multicast_list(struct device *dev)
+{
+	struct	cpm_enet_private *cep;
+	struct	dev_mc_list *dmi;
+	u_char	*mcptr, *tdptr;
+	volatile scc_enet_t *ep;
+	int	i, j;
+
+	cep = (struct cpm_enet_private *)dev->priv;
+
+	/* Get pointer to SCC1 area in parameter RAM.
+	*/
+	ep = (scc_enet_t *)dev->base_addr;
+
+	if (dev->flags&IFF_PROMISC) {
+		/* Log any net taps. */
+		printk("%s: Promiscuous mode enabled.\n", dev->name);
+		cep->sccp->scc_pmsr |= SCC_PMSR_PRO;
+	} else {
+
+		cep->sccp->scc_pmsr &= ~SCC_PMSR_PRO;
+
+		if (dev->flags & IFF_ALLMULTI) {
+			/* Catch all multicast addresses, so set the
+			 * filter to all 1's.
+			 */
+			ep->sen_gaddr1 = 0xffff;
+			ep->sen_gaddr2 = 0xffff;
+			ep->sen_gaddr3 = 0xffff;
+			ep->sen_gaddr4 = 0xffff;
+		}
+		else {
+			/* Clear filter and add the addresses in the list.
+			*/
+			ep->sen_gaddr1 = 0;
+			ep->sen_gaddr2 = 0;
+			ep->sen_gaddr3 = 0;
+			ep->sen_gaddr4 = 0;
+
+			dmi = dev->mc_list;
+
+			for (i=0; i<dev->mc_count; i++) {
+				
+				/* Only support group multicast for now.
+				*/
+				if (!(dmi->dmi_addr[0] & 1))
+					continue;
+
+				/* The address in dmi_addr is LSB first,
+				 * and taddr is MSB first.  We have to
+				 * copy bytes MSB first from dmi_addr.
+				 */
+				mcptr = (u_char *)dmi->dmi_addr + 5;
+				tdptr = (u_char *)&ep->sen_taddrh;
+				for (j=0; j<6; j++)
+					*tdptr++ = *mcptr--;
+
+				/* Ask CPM to run CRC and set bit in
+				 * filter mask.
+				 */
+				cpmp->cp_cpcr = mk_cr_cmd(CPM_CR_CH_SCC1, CPM_CR_SET_GADDR) | CPM_CR_FLG;
+				while (cpmp->cp_cpcr & CPM_CR_FLG);
+			}
+		}
+	}
+}
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TCL-scripts by Sam Shen, slshen@lbl.gov