enet.c

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/*
 * Ethernet driver for Motorola MPC8260.
 * Copyright (c) 1999 Dan Malek ([e-mail])
 * Copyright (c) 2000 MontaVista Software Inc. ([e-mail])
 *	2.3.99 Updates
 *
 * I copied this from the 8xx CPM Ethernet driver, so follow the
 * credits back through that.
 *
 * This version of the driver is somewhat selectable for the different
 * processor/board combinations.  It works for the boards I know about
 * now, and should be easily modified to include others.  Some of the
 * configuration information is contained in "commproc.h" and the
 * remainder is here.
 *
 * 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/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/init.h>
#include <linux/delay.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>

#include <asm/immap_8260.h>
#include <asm/pgtable.h>
#include <asm/mpc8260.h>
#include <asm/bitops.h>
#include <asm/uaccess.h>
#include <asm/cpm_8260.h>
#include <asm/irq.h>

/*
 *				Theory of Operation
 *
 * The MPC8260 CPM performs the Ethernet processing on an SCC.  It can use
 * an aribtrary number of buffers on byte boundaries, but must have at
 * least two receive buffers to prevent constant 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
 * cep->tx_busy flag.  The other thread is the interrupt handler, which is
 * single threaded by the hardware and other software.
 */

/* The transmitter timeout
 */
#define TX_TIMEOUT	(2*HZ)

/* 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 is 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 scc_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;
	uint	tx_full;
	spinlock_t lock;
};

static int scc_enet_open(struct net_device *dev);
static int scc_enet_start_xmit(struct sk_buff *skb, struct net_device *dev);
static int scc_enet_rx(struct net_device *dev);
static void scc_enet_interrupt(int irq, void * dev_id, struct pt_regs * regs);
static int scc_enet_close(struct net_device *dev);
static struct net_device_stats *scc_enet_get_stats(struct net_device *dev);
static void set_multicast_list(struct net_device *dev);

/* These will be configurable for the SCC choice.
*/
#define CPM_ENET_BLOCK	CPM_CR_SCC1_SBLOCK
#define CPM_ENET_PAGE	CPM_CR_SCC1_PAGE
#define PROFF_ENET	PROFF_SCC1
#define SCC_ENET	0
#define SIU_INT_ENET	SIU_INT_SCC1

/* These are both board and SCC dependent....
*/
#define PD_ENET_RXD	((uint)0x00000001)
#define PD_ENET_TXD	((uint)0x00000002)
#define PD_ENET_TENA	((uint)0x00000004)
#define PC_ENET_RENA	((uint)0x00020000)
#define PC_ENET_CLSN	((uint)0x00000004)
#define PC_ENET_TXCLK	((uint)0x00000800)
#define PC_ENET_RXCLK	((uint)0x00000400)
#define CMX_CLK_ROUTE	((uint)0x25000000)
#define CMX_CLK_MASK	((uint)0xff000000)

/* Specific to a board.
*/
#define PC_EST8260_ENET_LOOPBACK	((uint)0x80000000)
#define PC_EST8260_ENET_SQE		((uint)0x40000000)
#define PC_EST8260_ENET_NOTFD		((uint)0x20000000)

static int
scc_enet_open(struct net_device *dev)
{

	/* I should reset the ring buffers here, but I don't yet know
	 * a simple way to do that.
	 */
	netif_start_queue(dev);
	return 0;					/* Always succeed */
}

static int
scc_enet_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct scc_enet_private *cep = (struct scc_enet_private *)dev->priv;
	volatile cbd_t	*bdp;


	/* 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 cep->tx_full should be set.
		 */
		printk("%s: tx queue full!.\n", dev->name);
		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;
	
	spin_lock_irq(&cep->lock);

	/* 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++;

	if (bdp->cbd_sc & BD_ENET_TX_READY) {
		netif_stop_queue(dev);
		cep->tx_full = 1;
	}

	cep->cur_tx = (cbd_t *)bdp;

	spin_unlock_irq(&cep->lock);

	return 0;
}

static void
scc_enet_timeout(struct net_device *dev)
{
	struct scc_enet_private *cep = (struct scc_enet_private *)dev->priv;

	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 %p%s cur_rx %p.\n",
		       cep->cur_tx, cep->tx_full ? " (full)" : "",
		       cep->cur_rx);
		bdp = cep->tx_bd_base;
		printk(" Tx @base %p :\n", bdp);
		for (i = 0 ; i < TX_RING_SIZE; i++, bdp++)
			printk("%04x %04x %08x\n",
			       bdp->cbd_sc,
			       bdp->cbd_datlen,
			       bdp->cbd_bufaddr);
		bdp = cep->rx_bd_base;
		printk(" Rx @base %p :\n", bdp);
		for (i = 0 ; i < RX_RING_SIZE; i++, bdp++)
			printk("%04x %04x %08x\n",
			       bdp->cbd_sc,
			       bdp->cbd_datlen,
			       bdp->cbd_bufaddr);
	}
#endif
	if (!cep->tx_full)
		netif_wake_queue(dev);
}

/* The interrupt handler.
 * This is called from the CPM handler, not the MPC core interrupt.
 */
static void
scc_enet_interrupt(int irq, void * dev_id, struct pt_regs * regs)
{
	struct	net_device *dev = dev_id;
	volatile struct	scc_enet_private *cep;
	volatile cbd_t	*bdp;
	ushort	int_events;
	int	must_restart;

	cep = (struct scc_enet_private *)dev->priv;

	/* Get the interrupt events that caused us to be here.
	*/
	int_events = cep->sccp->scc_scce;
	cep->sccp->scc_scce = int_events;
	must_restart = 0;

	/* Handle receive event in its own function.
	*/
	if (int_events & SCCE_ENET_RXF)
		scc_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 :-).
	 */

	/* Transmit OK, or non-fatal error.  Update the buffer descriptors.
	*/
	if (int_events & (SCCE_ENET_TXE | SCCE_ENET_TXB)) {
	    spin_lock(&cep->lock);
	    bdp = cep->dirty_tx;
	    while ((bdp->cbd_sc&BD_ENET_TX_READY)==0) {
		if ((bdp==cep->cur_tx) && (cep->tx_full == 0))
		    break;

		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++;


		/* 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;
			cep->stats.tx_errors++;
		}

		cep->stats.tx_packets++;

		/* 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_irq(cep->tx_skbuff[cep->skb_dirty]);
		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) {
			cep->tx_full = 0;
			if (netif_queue_stopped(dev)) {
				netif_wake_queue(dev);
			}
		}

		cep->dirty_tx = (cbd_t *)bdp;
	    }

	    if (must_restart) {
		volatile cpm8260_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_ENET_PAGE, CPM_ENET_BLOCK, 0,
		    			CPM_CR_RESTART_TX) | CPM_CR_FLG;
		while (cp->cp_cpcr & CPM_CR_FLG);
	    }
	    spin_unlock(&cep->lock);
	}

	/* 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("SCC ENET: BSY can't happen.\n");
	}

	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
scc_enet_rx(struct net_device *dev)
{
	struct	scc_enet_private *cep;
	volatile cbd_t	*bdp;
	struct	sk_buff *skb;
	ushort	pkt_len;

	cep = (struct scc_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)