Subject: Re: [PATCH][MIPS][7/7] AR7: ethernet

From: Ralf Baechle <[email-masked]>
Date: Wed, 12 Sep 2007 17:50:29 +0100

On Sat, Sep 08, 2007 at 02:23:00AM +0200, Matteo Croce wrote:

> Driver for the cpmac 100M ethernet driver.
> It works fine disabling napi support, enabling it gives a kernel panic
> when the first IPv6 packet has to be forwarded.
> Other than that works fine.
> 
> Signed-off-by: Matteo Croce <[email-masked]>
> Signed-off-by: Eugene Konev <[email-masked]>
> 
> diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
> index d9b7d9c..6f38a84 100644
> --- a/drivers/net/Kconfig
> +++ b/drivers/net/Kconfig
> @@ -1822,6 +1822,15 @@ config SC92031
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called sc92031.  This is recommended.
>  
> +config CPMAC
> +	tristate "TI AR7 CPMAC Ethernet support (EXPERIMENTAL)"
> +	depends on NET_ETHERNET && EXPERIMENTAL && AR7

The dependency on NET_ETHERNET is not needed because this config block is
enclosed in a

    if NET_ETHERNET
    ...
    endif # NET_ETHERNET

block.

> +	select PHYLIB
> +	select FIXED_PHY
> +	select FIXED_MII_100_FDX
> +	help
> +	  TI AR7 CPMAC Ethernet support
> +
>  config NET_POCKET
>  	bool "Pocket and portable adapters"
>  	depends on PARPORT
> diff --git a/drivers/net/Makefile b/drivers/net/Makefile
> index 535d2a0..bb22df9 100644
> --- a/drivers/net/Makefile
> +++ b/drivers/net/Makefile
> @@ -156,6 +156,7 @@ obj-$(CONFIG_8139CP) += 8139cp.o
>  obj-$(CONFIG_8139TOO) += 8139too.o
>  obj-$(CONFIG_ZNET) += znet.o
>  obj-$(CONFIG_LAN_SAA9730) += saa9730.o
> +obj-$(CONFIG_CPMAC) += cpmac.o
>  obj-$(CONFIG_DEPCA) += depca.o
>  obj-$(CONFIG_EWRK3) += ewrk3.o
>  obj-$(CONFIG_ATP) += atp.o
> diff --git a/drivers/net/cpmac.c b/drivers/net/cpmac.c
> new file mode 100644
> index 0000000..c10ab08
> --- /dev/null
> +++ b/drivers/net/cpmac.c
> @@ -0,0 +1,1194 @@
> +/*
> + * Copyright (C) 2006, 2007 Eugene Konev
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
> + */
> +
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/moduleparam.h>
> +
> +#include <linux/sched.h>
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/errno.h>
> +#include <linux/types.h>
> +#include <linux/delay.h>
> +#include <linux/version.h>
> +
> +#include <linux/netdevice.h>
> +#include <linux/etherdevice.h>
> +#include <linux/ethtool.h>
> +#include <linux/skbuff.h>
> +#include <linux/mii.h>
> +#include <linux/phy.h>
> +#include <linux/platform_device.h>
> +#include <asm/ar7/ar7.h>
> +#include <gpio.h>
> +
> +MODULE_AUTHOR("Eugene Konev");
> +MODULE_DESCRIPTION("TI AR7 ethernet driver (CPMAC)");
> +MODULE_LICENSE("GPL");
> +
> +static int rx_ring_size = 64;
> +static int disable_napi;
> +module_param(rx_ring_size, int, 64);
> +module_param(disable_napi, int, 0);
> +MODULE_PARM_DESC(rx_ring_size, "Size of rx ring (in skbs)");
> +MODULE_PARM_DESC(disable_napi, "Disable NAPI polling");
> +
> +/* Register definitions */
> +struct cpmac_control_regs {
> +	u32 revision;
> +	u32 control;
> +	u32 teardown;
> +	u32 unused;
> +} __attribute__ ((packed));
> +
> +struct cpmac_int_regs {
> +	u32 stat_raw;
> +	u32 stat_masked;
> +	u32 enable;
> +	u32 clear;
> +} __attribute__ ((packed));
> +
> +struct cpmac_stats {
> +	u32 good;
> +	u32 bcast;
> +	u32 mcast;
> +	u32 pause;
> +	u32 crc_error;
> +	u32 align_error;
> +	u32 oversized;
> +	u32 jabber;
> +	u32 undersized;
> +	u32 fragment;
> +	u32 filtered;
> +	u32 qos_filtered;
> +	u32 octets;
> +} __attribute__ ((packed));

All struct members here are sized such that there is no padding needed, so
the packed attribute doesn't buy you anything - unless of course the
entire structure is missaligned but I don't see how that would be possible
in this driver so the __attribute__ ((packed)) should go - it result in
somwhat larger and slower code.

In any case, the __packed attribute is prefered over __attribute__ ((packed))
for readability sake.

> +
> +struct cpmac_regs {
> +	struct cpmac_control_regs tx_ctrl;
> +	struct cpmac_control_regs rx_ctrl;
> +	u32 unused1[56];
> +	u32 mbp;
> +/* MBP bits */
> +#define MBP_RXPASSCRC         0x40000000
> +#define MBP_RXQOS             0x20000000
> +#define MBP_RXNOCHAIN         0x10000000
> +#define MBP_RXCMF             0x01000000
> +#define MBP_RXSHORT           0x00800000
> +#define MBP_RXCEF             0x00400000
> +#define MBP_RXPROMISC         0x00200000
> +#define MBP_PROMISCCHAN(chan) (((chan) & 0x7) << 16)
> +#define MBP_RXBCAST           0x00002000
> +#define MBP_BCASTCHAN(chan)   (((chan) & 0x7) << 8)
> +#define MBP_RXMCAST           0x00000020
> +#define MBP_MCASTCHAN(chan)   ((chan) & 0x7)
> +	u32 unicast_enable;
> +	u32 unicast_clear;
> +	u32 max_len;
> +	u32 buffer_offset;
> +	u32 filter_flow_threshold;
> +	u32 unused2[2];
> +	u32 flow_thre[8];
> +	u32 free_buffer[8];
> +	u32 mac_control;
> +#define MAC_TXPTYPE  0x00000200
> +#define MAC_TXPACE   0x00000040
> +#define MAC_MII      0x00000020
> +#define MAC_TXFLOW   0x00000010
> +#define MAC_RXFLOW   0x00000008
> +#define MAC_MTEST    0x00000004
> +#define MAC_LOOPBACK 0x00000002
> +#define MAC_FDX      0x00000001
> +	u32 mac_status;
> +#define MACST_QOS    0x4
> +#define MACST_RXFLOW 0x2
> +#define MACST_TXFLOW 0x1
> +	u32 emc_control;
> +	u32 unused3;
> +	struct cpmac_int_regs tx_int;
> +	u32 mac_int_vector;
> +/* Int Status bits */
> +#define INTST_STATUS 0x80000
> +#define INTST_HOST   0x40000
> +#define INTST_RX     0x20000
> +#define INTST_TX     0x10000
> +	u32 mac_eoi_vector;
> +	u32 unused4[2];
> +	struct cpmac_int_regs rx_int;
> +	u32 mac_int_stat_raw;
> +	u32 mac_int_stat_masked;
> +	u32 mac_int_enable;
> +	u32 mac_int_clear;
> +	u32 mac_addr_low[8];
> +	u32 mac_addr_mid;
> +	u32 mac_addr_high;
> +	u32 mac_hash_low;
> +	u32 mac_hash_high;
> +	u32 boff_test;
> +	u32 pac_test;
> +	u32 rx_pause;
> +	u32 tx_pause;
> +	u32 unused5[2];
> +	struct cpmac_stats rx_stats;
> +	struct cpmac_stats tx_stats;
> +	u32 unused6[232];
> +	u32 tx_ptr[8];
> +	u32 rx_ptr[8];
> +	u32 tx_ack[8];
> +	u32 rx_ack[8];
> +
> +} __attribute__ ((packed));
> +
> +struct cpmac_mdio_regs {
> +	u32 version;
> +	u32 control;
> +#define MDIOC_IDLE        0x80000000
> +#define MDIOC_ENABLE      0x40000000
> +#define MDIOC_PREAMBLE    0x00100000
> +#define MDIOC_FAULT       0x00080000
> +#define MDIOC_FAULTDETECT 0x00040000
> +#define MDIOC_INTTEST     0x00020000
> +#define MDIOC_CLKDIV(div) ((div) & 0xff)
> +	u32 alive;
> +	u32 link;
> +	struct cpmac_int_regs link_int;
> +	struct cpmac_int_regs user_int;
> +	u32 unused[20];
> +	volatile u32 access;
> +#define MDIO_BUSY       0x80000000
> +#define MDIO_WRITE      0x40000000
> +#define MDIO_REG(reg)   (((reg) & 0x1f) << 21)
> +#define MDIO_PHY(phy)   (((phy) & 0x1f) << 16)
> +#define MDIO_DATA(data) ((data) & 0xffff)
> +	u32 physel;
> +} __attribute__ ((packed));
> +
> +/* Descriptor */
> +struct cpmac_desc {
> +	u32 hw_next;
> +	u32 hw_data;
> +	u16 buflen;
> +	u16 bufflags;
> +	u16 datalen;
> +	u16 dataflags;
> +/* Flags bits */
> +#define CPMAC_SOP 0x8000
> +#define CPMAC_EOP 0x4000
> +#define CPMAC_OWN 0x2000
> +#define CPMAC_EOQ 0x1000
> +	struct sk_buff *skb;
> +	struct cpmac_desc *next;
> +} __attribute__ ((packed));
> +
> +struct cpmac_priv {
> +	struct net_device_stats stats;
> +	spinlock_t lock; /* irq{save,restore} */
> +	struct sk_buff *skb_pool;
> +	int free_skbs;
> +	struct cpmac_desc *rx_head;
> +	int tx_head, tx_tail;
> +	struct cpmac_desc *desc_ring;
> +	struct cpmac_regs *regs;
> +	struct mii_bus *mii_bus;
> +	struct phy_device *phy;
> +	char phy_name[BUS_ID_SIZE];
> +	struct plat_cpmac_data *config;
> +	int oldlink, oldspeed, oldduplex;
> +	u32 msg_enable;
> +	struct net_device *dev;
> +	struct work_struct alloc_work;
> +};
> +
> +static irqreturn_t cpmac_irq(int, void *);
> +static void cpmac_reset(struct net_device *dev);
> +static void cpmac_hw_init(struct net_device *dev);
> +static int cpmac_stop(struct net_device *dev);
> +static int cpmac_open(struct net_device *dev);
> +
> +#undef CPMAC_DEBUG
> +#define CPMAC_LOW_THRESH 32
> +#define CPMAC_ALLOC_SIZE 64
> +#define CPMAC_SKB_SIZE 1518
> +#define CPMAC_TX_RING_SIZE 8
> +
> +#ifdef CPMAC_DEBUG
> +static void cpmac_dump_regs(u32 *base, int count)
> +{
> +	int i;
> +	for (i = 0; i < (count + 3) / 4; i++) {
> +		if (i % 4 == 0) printk(KERN_DEBUG "\nCPMAC[0x%04x]:", i * 4);
> +		printk(KERN_DEBUG " 0x%08x", *(base + i));
> +	}
> +	printk(KERN_DEBUG "\n");
> +}
> +
> +static const char *cpmac_dump_buf(const uint8_t *buf, unsigned size)
> +{
> +	static char buffer[3 * 25 + 1];
> +	char *p = &buffer[0];
> +	if (size > 20)
> +		size = 20;
> +	while (size-- > 0)
> +		p += sprintf(p, " %02x", *buf++);
> +	return buffer;
> +}
> +#endif
> +
> +static int cpmac_mdio_read(struct mii_bus *bus, int phy_id, int regnum)
> +{
> +	struct cpmac_mdio_regs *regs = bus->priv;
> +	u32 val;
> +
> +	while ((val = regs->access) & MDIO_BUSY);
> +	regs->access = MDIO_BUSY | MDIO_REG(regnum & 0x1f) |
> +		MDIO_PHY(phy_id & 0x1f);
> +	while ((val = regs->access) & MDIO_BUSY);
> +
> +	return val & 0xffff;
> +}
> +
> +static int cpmac_mdio_write(struct mii_bus *bus, int phy_id,
> +				int regnum, u16 val)
> +{
> +	struct cpmac_mdio_regs *regs = bus->priv;
> +
> +	while (regs->access & MDIO_BUSY);
> +	regs->access = MDIO_BUSY | MDIO_WRITE |
> +		MDIO_REG(regnum & 0x1f) | MDIO_PHY(phy_id & 0x1f) | val;
> +
> +	return 0;
> +}
> +
> +static int cpmac_mdio_reset(struct mii_bus *bus)
> +{
> +	ar7_device_reset(AR7_RESET_BIT_MDIO);
> +	((struct cpmac_mdio_regs *)bus->priv)->control = MDIOC_ENABLE |
> +		MDIOC_CLKDIV(ar7_cpmac_freq() / 2200000 - 1);
> +
> +	return 0;
> +}
> +
> +static int mii_irqs[PHY_MAX_ADDR] = { PHY_POLL, };
> +
> +static struct mii_bus cpmac_mii = {
> +	.name = "cpmac-mii",
> +	.read = cpmac_mdio_read,
> +	.write = cpmac_mdio_write,
> +	.reset = cpmac_mdio_reset,
> +	.irq = mii_irqs,
> +};
> +
> +static int cpmac_config(struct net_device *dev, struct ifmap *map)
> +{
> +	if (dev->flags & IFF_UP)
> +		return -EBUSY;
> +
> +	/* Don't allow changing the I/O address */
> +	if (map->base_addr != dev->base_addr)
> +		return -EOPNOTSUPP;
> +
> +	/* ignore other fields */
> +	return 0;
> +}
> +
> +static int cpmac_set_mac_address(struct net_device *dev, void *addr)
> +{
> +	struct sockaddr *sa = addr;
> +
> +	if (dev->flags & IFF_UP)
> +		return -EBUSY;
> +
> +	memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
> +
> +	return 0;
> +}
> +
> +static void cpmac_set_multicast_list(struct net_device *dev)
> +{
> +	struct dev_mc_list *iter;
> +	int i;
> +	int hash, tmp;
> +	int hashlo = 0, hashhi = 0;
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +
> +	if (dev->flags & IFF_PROMISC) {
> +		priv->regs->mbp &= ~MBP_PROMISCCHAN(0); /* promisc channel 0 */
> +		priv->regs->mbp |= MBP_RXPROMISC;
> +	} else {
> +		priv->regs->mbp &= ~MBP_RXPROMISC;
> +		if (dev->flags & IFF_ALLMULTI) {
> +			/* enable all multicast mode */
> +			priv->regs->mac_hash_low = 0xffffffff;
> +			priv->regs->mac_hash_high = 0xffffffff;
> +		} else {
> +			for (i = 0, iter = dev->mc_list; i < dev->mc_count;
> +			    i++, iter = iter->next) {
> +				hash = 0;
> +				tmp = iter->dmi_addr[0];
> +				hash  ^= (tmp >> 2) ^ (tmp << 4);
> +				tmp = iter->dmi_addr[1];
> +				hash  ^= (tmp >> 4) ^ (tmp << 2);
> +				tmp = iter->dmi_addr[2];
> +				hash  ^= (tmp >> 6) ^ tmp;
> +				tmp = iter->dmi_addr[4];
> +				hash  ^= (tmp >> 2) ^ (tmp << 4);
> +				tmp = iter->dmi_addr[5];
> +				hash  ^= (tmp >> 4) ^ (tmp << 2);
> +				tmp = iter->dmi_addr[6];
> +				hash  ^= (tmp >> 6) ^ tmp;
> +				hash &= 0x3f;
> +				if (hash < 32) {
> +					hashlo |= 1<<hash;
> +				} else {
> +					hashhi |= 1<<(hash - 32);
> +				}
> +			}
> +
> +			priv->regs->mac_hash_low = hashlo;
> +			priv->regs->mac_hash_high = hashhi;
> +		}
> +	}
> +}
> +
> +static struct sk_buff *cpmac_get_skb(struct net_device *dev)
> +{
> +	struct sk_buff *skb;
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +
> +	skb = priv->skb_pool;
> +	if (likely(skb))
> +		priv->skb_pool = skb->next;
> +	else {
> +		skb = dev_alloc_skb(CPMAC_SKB_SIZE + 2);
> +		if (skb) {
> +			skb->next = NULL;
> +			skb_reserve(skb, 2);
> +			skb->dev = priv->dev;
> +		}
> +	}
> +
> +	if (likely(priv->free_skbs))
> +		priv->free_skbs--;
> +
> +	if (priv->free_skbs < CPMAC_LOW_THRESH)
> +		schedule_work(&priv->alloc_work);
> +
> +	return skb;
> +}
> +
> +static struct sk_buff *cpmac_rx_one(struct net_device *dev,
> +					   struct cpmac_priv *priv,
> +					   struct cpmac_desc *desc)
> +{
> +	unsigned long flags;
> +	char *data;
> +	struct sk_buff *skb, *result = NULL;
> +
> +	priv->regs->rx_ack[0] = virt_to_phys(desc);
> +	if (unlikely(!desc->datalen)) {
> +		if (printk_ratelimit())
> +			printk(KERN_WARNING "%s: rx: spurious interrupt\n",
> +			       dev->name);
> +		priv->stats.rx_errors++;
> +		return NULL;
> +	}
> +
> +	spin_lock_irqsave(&priv->lock, flags);
> +	skb = cpmac_get_skb(dev);
> +	if (likely(skb)) {
> +		data = (char *)phys_to_virt(desc->hw_data);
> +		dma_cache_inv((u32)data, desc->datalen);
> +		skb_put(desc->skb, desc->datalen);
> +		desc->skb->protocol = eth_type_trans(desc->skb, dev);
> +		desc->skb->ip_summed = CHECKSUM_NONE;
> +		priv->stats.rx_packets++;
> +		priv->stats.rx_bytes += desc->datalen;
> +		result = desc->skb;
> +		desc->skb = skb;
> +	} else {
> +#ifdef CPMAC_DEBUG
> +		if (printk_ratelimit())
> +			printk(KERN_NOTICE "%s: low on skbs, dropping packet\n",
> +			       dev->name);
> +#endif
> +		priv->stats.rx_dropped++;
> +	}
> +	spin_unlock_irqrestore(&priv->lock, flags);
> +
> +	desc->hw_data = virt_to_phys(desc->skb->data);
> +	desc->buflen = CPMAC_SKB_SIZE;
> +	desc->dataflags = CPMAC_OWN;
> +	dma_cache_wback((u32)desc, 16);
> +
> +	return result;
> +}
> +
> +static void cpmac_rx(struct net_device *dev)
> +{
> +	struct sk_buff *skb;
> +	struct cpmac_desc *desc;
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +
> +	spin_lock(&priv->lock);
> +	if (unlikely(!priv->rx_head)) {
> +		spin_unlock(&priv->lock);
> +		return;
> +	}
> +
> +	desc = priv->rx_head;
> +	dma_cache_inv((u32)desc, 16);
> +#ifdef CPMAC_DEBUG
> +	printk(KERN_DEBUG "%s: len=%d, %s\n", __func__, pkt->datalen,
> +		cpmac_dump_buf(data, pkt->datalen));
> +#endif
> +
> +	while ((desc->dataflags & CPMAC_OWN) == 0) {
> +		skb = cpmac_rx_one(dev, priv, desc);
> +		if (likely(skb))
> +			netif_rx(skb);
> +		desc = desc->next;
> +		dma_cache_inv((u32)desc, 16);
> +	}
> +
> +	priv->rx_head = desc;
> +	priv->regs->rx_ptr[0] = virt_to_phys(desc);
> +	spin_unlock(&priv->lock);
> +}
> +
> +static int cpmac_poll(struct net_device *dev, int *budget)
> +{
> +	struct sk_buff *skb;
> +	struct cpmac_desc *desc;
> +	int received = 0, quota = min(dev->quota, *budget);
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +
> +	if (unlikely(!priv->rx_head)) {
> +		if (printk_ratelimit())
> +			printk(KERN_NOTICE "%s: rx: polling, but no queue\n",
> +			       dev->name);
> +		netif_rx_complete(dev);
> +		return 0;
> +	}
> +
> +	desc = priv->rx_head;
> +	dma_cache_inv((u32)desc, 16);
> +
> +	while ((received < quota) && ((desc->dataflags & CPMAC_OWN) == 0)) {
> +		skb = cpmac_rx_one(dev, priv, desc);
> +		if (likely(skb)) {
> +			netif_receive_skb(skb);
> +			received++;
> +		}
> +		desc = desc->next;
> +		priv->rx_head = desc;
> +		dma_cache_inv((u32)desc, 16);
> +	}
> +
> +	*budget -= received;
> +	dev->quota -= received;
> +#ifdef CPMAC_DEBUG
> +	printk(KERN_DEBUG "%s: processed %d packets\n", dev->name, received);
> +#endif
> +	if (desc->dataflags & CPMAC_OWN) {
> +		priv->regs->rx_ptr[0] = virt_to_phys(desc);
> +		netif_rx_complete(dev);
> +		priv->regs->rx_int.enable = 0x1;
> +		priv->regs->rx_int.clear = 0xfe;
> +		return 0;
> +	}
> +
> +	return 1;
> +}
> +
> +static void
> +cpmac_alloc_skbs(struct work_struct *work)
> +{
> +	struct cpmac_priv *priv = container_of(work, struct cpmac_priv,
> +			alloc_work);
> +	unsigned long flags;
> +	int i, num_skbs = 0;
> +	struct sk_buff *skb, *skbs = NULL;
> +
> +	for (i = 0; i < CPMAC_ALLOC_SIZE; i++) {
> +		skb = alloc_skb(CPMAC_SKB_SIZE + 2, GFP_KERNEL);
> +		if (!skb)
> +			break;
> +		skb->next = skbs;
> +		skb_reserve(skb, 2);
> +		skb->dev = priv->dev;
> +		num_skbs++;
> +		skbs = skb;
> +	}
> +
> +	if (skbs) {
> +		spin_lock_irqsave(&priv->lock, flags);
> +		for (skb = priv->skb_pool; skb && skb->next; skb = skb->next);
> +		if (!skb)
> +			priv->skb_pool = skbs;
> +		else
> +			skb->next = skbs;
> +		priv->free_skbs += num_skbs;
> +		spin_unlock_irqrestore(&priv->lock, flags);
> +#ifdef CPMAC_DEBUG
> +		printk(KERN_DEBUG "%s: allocated %d skbs\n",
> +			priv->dev->name, num_skbs);
> +#endif
> +	}
> +}
> +
> +static int cpmac_start_xmit(struct sk_buff *skb, struct net_device *dev)
> +{
> +	unsigned long flags;
> +	int len, chan;
> +	struct cpmac_desc *desc;
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +
> +	len = skb->len;
> +#ifdef CPMAC_DEBUG
> +	printk(KERN_DEBUG "%s: len=%d\n", __func__, len);
> +	/* cpmac_dump_buf(const uint8_t * buf, unsigned size) */
> +#endif
> +	if (unlikely(len < ETH_ZLEN)) {
> +		if (unlikely(skb_padto(skb, ETH_ZLEN))) {
> +			if (printk_ratelimit())
> +				printk(KERN_NOTICE
> +					"%s: padding failed, dropping\n",
> +								dev->name);
> +			spin_lock_irqsave(&priv->lock, flags);
> +			priv->stats.tx_dropped++;
> +			spin_unlock_irqrestore(&priv->lock, flags);
> +			return -ENOMEM;
> +		}
> +		len = ETH_ZLEN;
> +	}
> +	spin_lock_irqsave(&priv->lock, flags);
> +	chan = priv->tx_tail++;
> +	priv->tx_tail %= 8;
> +	if (priv->tx_tail == priv->tx_head)
> +		netif_stop_queue(dev);
> +
> +	desc = &priv->desc_ring[chan];
> +	dma_cache_inv((u32)desc, 16);
> +	if (desc->dataflags & CPMAC_OWN) {
> +		printk(KERN_NOTICE "%s: tx dma ring full, dropping\n",
> +								dev->name);
> +		priv->stats.tx_dropped++;
> +		spin_unlock_irqrestore(&priv->lock, flags);
> +		return -ENOMEM;
> +	}
> +
> +	dev->trans_start = jiffies;
> +	desc->dataflags = CPMAC_SOP | CPMAC_EOP | CPMAC_OWN;
> +	desc->skb = skb;
> +	desc->hw_data = virt_to_phys(skb->data);
> +	dma_cache_wback((u32)skb->data, len);
> +	desc->buflen = len;
> +	desc->datalen = len;
> +	desc->hw_next = 0;
> +	dma_cache_wback((u32)desc, 16);
> +	priv->regs->tx_ptr[chan] = virt_to_phys(desc);
> +	spin_unlock_irqrestore(&priv->lock, flags);
> +
> +	return 0;
> +}
> +
> +static void cpmac_end_xmit(struct net_device *dev, int channel)
> +{
> +	struct cpmac_desc *desc;
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +
> +	spin_lock(&priv->lock);
> +	desc = &priv->desc_ring[channel];
> +	priv->regs->tx_ack[channel] = virt_to_phys(desc);
> +	if (likely(desc->skb)) {
> +		priv->stats.tx_packets++;
> +		priv->stats.tx_bytes += desc->skb->len;
> +		dev_kfree_skb_irq(desc->skb);
> +		if (netif_queue_stopped(dev))
> +			netif_wake_queue(dev);
> +	} else
> +		if (printk_ratelimit())
> +			printk(KERN_NOTICE "%s: end_xmit: spurious interrupt\n",
> +			       dev->name);
> +	spin_unlock(&priv->lock);
> +}
> +
> +static void cpmac_reset(struct net_device *dev)
> +{
> +	int i;
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +
> +	ar7_device_reset(priv->config->reset_bit);
> +	priv->regs->rx_ctrl.control &= ~1;
> +	priv->regs->tx_ctrl.control &= ~1;
> +	for (i = 0; i < 8; i++) {
> +		priv->regs->tx_ptr[i] = 0;
> +		priv->regs->rx_ptr[i] = 0;
> +	}
> +	priv->regs->mac_control &= ~MAC_MII; /* disable mii */
> +}
> +
> +static inline void cpmac_free_rx_ring(struct net_device *dev)
> +{
> +	struct cpmac_desc *desc;
> +	int i;
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +
> +	if (unlikely(!priv->rx_head))
> +		return;
> +
> +	desc = priv->rx_head;
> +	dma_cache_inv((u32)desc, 16);
> +
> +	for (i = 0; i < rx_ring_size; i++) {
> +		desc->buflen = CPMAC_SKB_SIZE;
> +		if ((desc->dataflags & CPMAC_OWN) == 0) {
> +			desc->dataflags = CPMAC_OWN;
> +			priv->stats.rx_dropped++;
> +		}
> +		dma_cache_wback((u32)desc, 16);
> +		desc = desc->next;
> +		dma_cache_inv((u32)desc, 16);
> +	}
> +}
> +
> +static irqreturn_t cpmac_irq(int irq, void *dev_id)
> +{
> +	struct net_device *dev = dev_id;
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +	u32 status;
> +
> +	if (!dev)
> +		return IRQ_NONE;
> +
> +	status = priv->regs->mac_int_vector;
> +
> +	if (status & INTST_TX)
> +		cpmac_end_xmit(dev, (status & 7));
> +
> +	if (status & INTST_RX) {
> +		if (disable_napi)
> +			cpmac_rx(dev);
> +		else {
> +			priv->regs->rx_int.enable = 0;
> +			priv->regs->rx_int.clear = 0xff;
> +			netif_rx_schedule(dev);
> +		}
> +	}
> +
> +	priv->regs->mac_eoi_vector = 0;
> +
> +	if (unlikely(status & (INTST_HOST | INTST_STATUS))) {
> +		if (printk_ratelimit())
> +			printk(KERN_ERR "%s: hw error, resetting...\n",
> +								dev->name);
> +		spin_lock(&priv->lock);
> +		phy_stop(priv->phy);
> +		cpmac_reset(dev);
> +		cpmac_free_rx_ring(dev);
> +		cpmac_hw_init(dev);
> +		spin_unlock(&priv->lock);
> +	}
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static void cpmac_tx_timeout(struct net_device *dev)
> +{
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +	struct cpmac_desc *desc;
> +
> +	priv->stats.tx_errors++;
> +	desc = &priv->desc_ring[priv->tx_head++];
> +	priv->tx_head %= 8;
> +	printk(KERN_NOTICE "%s: transmit timeout\n", dev->name);
> +	if (desc->skb)
> +		dev_kfree_skb(desc->skb);
> +	netif_wake_queue(dev);
> +}
> +
> +static int cpmac_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
> +{
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +	if (!(netif_running(dev)))
> +		return -EINVAL;
> +	if (!priv->phy)
> +		return -EINVAL;
> +	if ((cmd == SIOCGMIIPHY) || (cmd == SIOCGMIIREG) ||
> +	    (cmd == SIOCSMIIREG))
> +		return phy_mii_ioctl(priv->phy, if_mii(ifr), cmd);
> +
> +	return -EINVAL;
> +}
> +
> +static int cpmac_get_settings(struct net_device *dev, struct ethtool_cmd *cmd)
> +{
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +
> +	if (priv->phy)
> +		return phy_ethtool_gset(priv->phy, cmd);
> +
> +	return -EINVAL;
> +}
> +
> +static int cpmac_set_settings(struct net_device *dev, struct ethtool_cmd *cmd)
> +{
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +
> +	if (!capable(CAP_NET_ADMIN))
> +		return -EPERM;
> +
> +	if (priv->phy)
> +		return phy_ethtool_sset(priv->phy, cmd);
> +
> +	return -EINVAL;
> +}
> +
> +static void cpmac_get_drvinfo(struct net_device *dev,
> +			      struct ethtool_drvinfo *info)
> +{
> +	strcpy(info->driver, "cpmac");
> +	strcpy(info->version, "0.0.3");
> +	info->fw_version[0] = '\0';
> +	sprintf(info->bus_info, "%s", "cpmac");
> +	info->regdump_len = 0;
> +}
> +
> +static const struct ethtool_ops cpmac_ethtool_ops = {
> +	.get_settings = cpmac_get_settings,
> +	.set_settings = cpmac_set_settings,
> +	.get_drvinfo = cpmac_get_drvinfo,
> +	.get_link = ethtool_op_get_link,
> +};
> +
> +static struct net_device_stats *cpmac_stats(struct net_device *dev)
> +{
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +
> +	if (netif_device_present(dev))
> +		return &priv->stats;
> +
> +	return NULL;
> +}
> +
> +static int cpmac_change_mtu(struct net_device *dev, int mtu)
> +{
> +	unsigned long flags;
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +	spinlock_t *lock = &priv->lock;
> +
> +	if ((mtu < 68) || (mtu > 1500))
> +		return -EINVAL;
> +
> +	spin_lock_irqsave(lock, flags);
> +	dev->mtu = mtu;
> +	spin_unlock_irqrestore(lock, flags);
> +
> +	return 0;
> +}
> +
> +static void cpmac_adjust_link(struct net_device *dev)
> +{
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +	unsigned long flags;
> +	int new_state = 0;
> +
> +	spin_lock_irqsave(&priv->lock, flags);
> +	if (priv->phy->link) {
> +		if (priv->phy->duplex != priv->oldduplex) {
> +			new_state = 1;
> +			priv->oldduplex = priv->phy->duplex;
> +		}
> +
> +		if (priv->phy->speed != priv->oldspeed) {
> +			new_state = 1;
> +			priv->oldspeed = priv->phy->speed;
> +		}
> +
> +		if (!priv->oldlink) {
> +			new_state = 1;
> +			priv->oldlink = 1;
> +			netif_schedule(dev);
> +		}
> +	} else if (priv->oldlink) {
> +		new_state = 1;
> +		priv->oldlink = 0;
> +		priv->oldspeed = 0;
> +		priv->oldduplex = -1;
> +	}
> +
> +	if (new_state)
> +		phy_print_status(priv->phy);
> +
> +	spin_unlock_irqrestore(&priv->lock, flags);
> +}
> +
> +static void cpmac_hw_init(struct net_device *dev)
> +{
> +	int i;
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +
> +	for (i = 0; i < 8; i++)
> +		priv->regs->tx_ptr[i] = 0;
> +	priv->regs->rx_ptr[0] = virt_to_phys(priv->rx_head);
> +
> +	priv->regs->mbp = MBP_RXSHORT | MBP_RXBCAST | MBP_RXMCAST;
> +	priv->regs->unicast_enable = 0x1;
> +	priv->regs->unicast_clear = 0xfe;
> +	priv->regs->buffer_offset = 0;
> +	for (i = 0; i < 8; i++)
> +		priv->regs->mac_addr_low[i] = dev->dev_addr[5];
> +	priv->regs->mac_addr_mid = dev->dev_addr[4];
> +	priv->regs->mac_addr_high = dev->dev_addr[0] | (dev->dev_addr[1] << 8)
> +		| (dev->dev_addr[2] << 16) | (dev->dev_addr[3] << 24);
> +	priv->regs->max_len = CPMAC_SKB_SIZE;
> +	priv->regs->rx_int.enable = 0x1;
> +	priv->regs->rx_int.clear = 0xfe;
> +	priv->regs->tx_int.enable = 0xff;
> +	priv->regs->tx_int.clear = 0;
> +	priv->regs->mac_int_enable = 3;
> +	priv->regs->mac_int_clear = 0xfc;
> +
> +	priv->regs->rx_ctrl.control |= 1;
> +	priv->regs->tx_ctrl.control |= 1;
> +	priv->regs->mac_control |= MAC_MII | MAC_FDX;
> +
> +	priv->phy->state = PHY_CHANGELINK;
> +	phy_start(priv->phy);
> +}
> +
> +static int cpmac_open(struct net_device *dev)
> +{
> +	int i, size, res;
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +	struct cpmac_desc *desc;
> +	struct sk_buff *skb;
> +
> +	priv->phy = phy_connect(dev, priv->phy_name, &cpmac_adjust_link,
> +				0, PHY_INTERFACE_MODE_MII);
> +	if (IS_ERR(priv->phy)) {
> +		printk(KERN_ERR "%s: Could not attach to PHY\n", dev->name);
> +		return PTR_ERR(priv->phy);
> +	}
> +
> +	if (!request_mem_region(dev->mem_start, dev->mem_end -
> +				dev->mem_start, dev->name)) {
> +		printk(KERN_ERR "%s: failed to request registers\n",
> +		       dev->name);
> +		res = -ENXIO;
> +		goto fail_reserve;
> +	}
> +
> +	priv->regs = ioremap_nocache(dev->mem_start, dev->mem_end -
> +				     dev->mem_start);
> +	if (!priv->regs) {
> +		printk(KERN_ERR "%s: failed to remap registers\n", dev->name);
> +		res = -ENXIO;
> +		goto fail_remap;
> +	}
> +
> +	priv->rx_head = NULL;
> +	size = sizeof(struct cpmac_desc) * (rx_ring_size +
> +					    CPMAC_TX_RING_SIZE);
> +	priv->desc_ring = (struct cpmac_desc *)kmalloc(size, GFP_KERNEL);

kmalloc returns void * so no cast to another pointer type necessary.

> +	if (!priv->desc_ring) {
> +		res = -ENOMEM;
> +		goto fail_alloc;
> +	}
> +
> +	memset((char *)priv->desc_ring, 0, size);

Use kzalloc instead of kmalloc.  kzalloc is like kmalloc but returns
zero'd memory.

> +	priv->skb_pool = NULL;
> +	priv->free_skbs = 0;
> +	priv->rx_head = &priv->desc_ring[CPMAC_TX_RING_SIZE];
> +
> +	INIT_WORK(&priv->alloc_work, cpmac_alloc_skbs);
> +	schedule_work(&priv->alloc_work);
> +	flush_scheduled_work();
> +
> +	for (i = 0; i < rx_ring_size; i++) {
> +		desc = &priv->rx_head[i];
> +		skb = cpmac_get_skb(dev);
> +		if (!skb) {
> +			res = -ENOMEM;
> +			goto fail_desc;
> +		}
> +		desc->skb = skb;
> +		desc->hw_data = virt_to_phys(skb->data);
> +		desc->buflen = CPMAC_SKB_SIZE;
> +		desc->dataflags = CPMAC_OWN;
> +		desc->next = &priv->rx_head[(i + 1) % rx_ring_size];
> +		desc->hw_next = virt_to_phys(desc->next);
> +		dma_cache_wback((u32)desc, 16);
> +	}
> +
> +	if ((res = request_irq(dev->irq, cpmac_irq, SA_INTERRUPT,
> +			      dev->name, dev))) {
> +		printk(KERN_ERR "%s: failed to obtain irq\n", dev->name);
> +		goto fail_irq;
> +	}
> +
> +	cpmac_reset(dev);
> +	cpmac_hw_init(dev);
> +
> +	netif_start_queue(dev);
> +	return 0;
> +
> +fail_irq:
> +fail_desc:
> +	for (i = 0; i < rx_ring_size; i++)
> +		if (priv->rx_head[i].skb)
> +			kfree_skb(priv->rx_head[i].skb);
> +fail_alloc:
> +	kfree(priv->desc_ring);
> +
> +	for (skb = priv->skb_pool; skb; skb = priv->skb_pool) {
> +		priv->skb_pool = skb->next;
> +		kfree_skb(skb);
> +	}
> +
> +	iounmap(priv->regs);
> +
> +fail_remap:
> +	release_mem_region(dev->mem_start, dev->mem_end -
> +			   dev->mem_start);
> +
> +fail_reserve:
> +	phy_disconnect(priv->phy);
> +
> +	return res;
> +}
> +
> +static int cpmac_stop(struct net_device *dev)
> +{
> +	int i;
> +	struct sk_buff *skb;
> +	struct cpmac_priv *priv = netdev_priv(dev);
> +
> +	netif_stop_queue(dev);
> +
> +	phy_stop(priv->phy);
> +	phy_disconnect(priv->phy);
> +	priv->phy = NULL;
> +
> +	cpmac_reset(dev);
> +
> +	for (i = 0; i < 8; i++) {
> +		priv->regs->rx_ptr[i] = 0;
> +		priv->regs->tx_ptr[i] = 0;
> +		priv->regs->mbp = 0;
> +	}
> +
> +	free_irq(dev->irq, dev);
> +	release_mem_region(dev->mem_start, dev->mem_end -
> +			   dev->mem_start);
> +
> +	cancel_delayed_work(&priv->alloc_work);
> +	flush_scheduled_work();
> +
> +	priv->rx_head = &priv->desc_ring[CPMAC_TX_RING_SIZE];
> +	for (i = 0; i < rx_ring_size; i++)
> +		if (priv->rx_head[i].skb)
> +			kfree_skb(priv->rx_head[i].skb);
> +
> +	kfree(priv->desc_ring);
> +
> +	for (skb = priv->skb_pool; skb; skb = priv->skb_pool) {
> +		priv->skb_pool = skb->next;
> +		kfree_skb(skb);
> +	}
> +
> +	return 0;
> +}
> +
> +static int external_switch;
> +
> +static int __devinit cpmac_probe(struct platform_device *pdev)
> +{
> +	int i, rc, phy_id;
> +	struct resource *res;
> +	struct cpmac_priv *priv;
> +	struct net_device *dev;
> +	struct plat_cpmac_data *pdata;
> +
> +	pdata = pdev->dev.platform_data;
> +
> +	for (phy_id = 0; phy_id < PHY_MAX_ADDR; phy_id++) {
> +		if (!(pdata->phy_mask & (1 << phy_id)))
> +			continue;
> +		if (!cpmac_mii.phy_map[phy_id])
> +			continue;
> +		break;
> +	}
> +
> +	if (phy_id == PHY_MAX_ADDR) {
> +		if (external_switch)
> +			phy_id = 0;
> +		else {
> +			printk(KERN_ERR "cpmac: no PHY present\n");
> +			return -ENODEV;
> +		}
> +	}
> +
> +	dev = alloc_etherdev(sizeof(struct cpmac_priv));
> +
> +	if (!dev) {
> +		printk(KERN_ERR
> +			"cpmac: Unable to allocate net_device structure!\n");
> +		return -ENOMEM;
> +	}
> +
> +	SET_MODULE_OWNER(dev);

Set SET_MODULE_OWNER is a useless nop which only exists in 2.6 for
driver source compatibility with 2.4.  So you can remove this call.

I used the opportunity to send out a patch to remove SET_MODULE_OWNER
from the kernel entirely.

> +	platform_set_drvdata(pdev, dev);
> +	priv = netdev_priv(dev);
> +
> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs");
> +	if (!res) {
> +		rc = -ENODEV;
> +		goto fail;
> +	}
> +
> +	dev->mem_start = res->start;
> +	dev->mem_end = res->end;
> +	dev->irq = platform_get_irq_byname(pdev, "irq");
> +
> +	dev->mtu                = 1500;

Initializing this field is redundant; alloc_etherdev has already done it,
so remove this line.

> +	dev->open               = cpmac_open;
> +	dev->stop               = cpmac_stop;
> +	dev->set_config         = cpmac_config;
> +	dev->hard_start_xmit    = cpmac_start_xmit;
> +	dev->do_ioctl           = cpmac_ioctl;
> +	dev->get_stats          = cpmac_stats;
> +	dev->change_mtu         = cpmac_change_mtu;
> +	dev->set_mac_address    = cpmac_set_mac_address;
> +	dev->set_multicast_list = cpmac_set_multicast_list;
> +	dev->tx_timeout         = cpmac_tx_timeout;
> +	dev->ethtool_ops        = &cpmac_ethtool_ops;
> +	if (!disable_napi) {
> +		dev->poll = cpmac_poll;
> +		dev->weight = min(rx_ring_size, 64);
> +	}
> +
> +	memset(priv, 0, sizeof(struct cpmac_priv));

Useless, alloc_etherdev does that already.

> +	spin_lock_init(&priv->lock);
> +	priv->msg_enable = netif_msg_init(NETIF_MSG_WOL, 0x3fff);
> +	priv->config = pdata;
> +	priv->dev = dev;
> +	memcpy(dev->dev_addr, priv->config->dev_addr, sizeof(dev->dev_addr));
> +	if (phy_id == 31)
> +		snprintf(priv->phy_name, BUS_ID_SIZE, PHY_ID_FMT,
> +			 cpmac_mii.id, phy_id);
> +	else
> +		snprintf(priv->phy_name, BUS_ID_SIZE, "fixed@%d:%d", 100, 1);
> +
> +	if ((rc = register_netdev(dev))) {
> +		printk(KERN_ERR "cpmac: error %i registering device %s\n",
> +		       rc, dev->name);
> +		goto fail;
> +	}
> +
> +	printk(KERN_INFO "cpmac: device %s (regs: %p, irq: %d, phy: %s, mac: ",
> +	       dev->name, (u32 *)dev->mem_start, dev->irq,
> +	       priv->phy_name);
> +	for (i = 0; i < 6; i++)
> +		printk("%02x%s", dev->dev_addr[i], i < 5 ? ":" : ")\n");
> +
> +	return 0;
> +
> +fail:
> +	free_netdev(dev);
> +	return rc;
> +}
> +
> +static int __devexit cpmac_remove(struct platform_device *pdev)
> +{
> +	struct net_device *dev = platform_get_drvdata(pdev);
> +	unregister_netdev(dev);
> +	free_netdev(dev);
> +	return 0;
> +}
> +
> +static struct platform_driver cpmac_driver = {
> +	.driver.name = "cpmac",
> +	.probe = cpmac_probe,
> +	.remove = cpmac_remove,

This should be:

	.remove = __devexit_p(cpmac_remove),

to avoid the final link from blowing up when the driver is built into the
kernel.

> +};
> +
> +int __devinit cpmac_init(void)

Make this function static; no need to export.

> +{
> +	u32 mask;
> +	int i, res;
> +	cpmac_mii.priv =
> +		ioremap_nocache(AR7_REGS_MDIO, sizeof(struct cpmac_mdio_regs));
> +
> +	if (!cpmac_mii.priv) {
> +		printk(KERN_ERR "Can't ioremap mdio registers\n");
> +		return -ENXIO;
> +	}
> +
> +#warning FIXME: unhardcode gpio&reset bits

Seeing such warnings always gives me a warm fuzzy feeling ;-)

> +	ar7_gpio_disable(26);
> +	ar7_gpio_disable(27);
> +	ar7_device_reset(AR7_RESET_BIT_CPMAC_LO);
> +	ar7_device_reset(AR7_RESET_BIT_CPMAC_HI);
> +	ar7_device_reset(AR7_RESET_BIT_EPHY);
> +
> +	cpmac_mii.reset(&cpmac_mii);
> +
> +	for (i = 0; i < 300000; i++) {
> +		mask = ((struct cpmac_mdio_regs *)cpmac_mii.priv)->alive;
> +		if (mask)
> +			break;
> +	}
> +
> +/*	mask &= 0x7fffffff;
> +	if (mask & (mask - 1)) {*/
> +		external_switch = 1;
> +		mask = 0;
> +/*	}*/
> +
> +	cpmac_mii.phy_mask = ~(mask | 0x80000000);
> +
> +	res = mdiobus_register(&cpmac_mii);
> +	if (res)
> +		goto fail_mii;
> +
> +	res = platform_driver_register(&cpmac_driver);
> +	if (res)
> +		goto fail_cpmac;
> +
> +	return 0;
> +
> +fail_cpmac:
> +	mdiobus_unregister(&cpmac_mii);
> +
> +fail_mii:
> +	iounmap(cpmac_mii.priv);
> +
> +	return res;
> +}
> +
> +void __devexit cpmac_exit(void)
> +{
> +	platform_driver_unregister(&cpmac_driver);
> +	mdiobus_unregister(&cpmac_mii);
> +}
> +
> +module_init(cpmac_init);
> +module_exit(cpmac_exit);

Time to run ...

  Ralf