Fix/Rewrite of the mipsnet driver]

This is Thiemo's patch.

----- Forwarded message from Thiemo Seufer <ths@networkno.de> -----

From: Thiemo Seufer <ths@networkno.de>
Date: Sat, 17 Nov 2007 22:29:13 +0000
To: netdev@vger.kernel.org
Cc: linux-mips@linux-mips.org, ralf@linux-mips.org
Subject: [PATCH, REPOST] Fix/Rewrite of the mipsnet driver
Content-Type: text/plain; charset=us-ascii

Hello All,

currently the mipsnet driver fails after transmitting a number of
packages because SKBs are allocated but never freed. I fixed that
and coudn't refrain from removing the most egregious warts.

- mipsnet.h folded into mipsnet.c, as it doesn't provide any
  useful external interface.
- Free SKB after transmission.
- Call free_irq in mipsnet_close, to balance the request_irq in
  mipsnet_open.
- Removed duplicate read of rxDataCount.
- Some identifiers are now less verbose.
- Removed dead and/or unnecessarily complex code.
- Code formatting fixes.

Tested on Qemu's mipssim emulation, with this patch it can boot a
Debian NFSroot.

Thiemo

Signed-off-by: Thiemo Seufer <ths@networkno.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 135 insertions, 68 deletions

diff --git a/drivers/net/mipsnet.c b/drivers/net/mipsnet.c
index aafc3ce59cbb..6d343efb2717 100644
--- a/drivers/net/mipsnet.c
+++ b/drivers/net/mipsnet.c
@@ -4,8 +4,6 @@
  * for more details.
  */
 
-#define DEBUG
-
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
@@ -15,11 +13,93 @@
 #include <linux/platform_device.h>
 #include <asm/mips-boards/simint.h>
 
-#include "mipsnet.h"		/* actual device IO mapping */
+#define MIPSNET_VERSION "2007-11-17"
+
+/*
+ * Net status/control block as seen by sw in the core.
+ */
+struct mipsnet_regs {
+	/*
+	 * Device info for probing, reads as MIPSNET%d where %d is some
+	 * form of version.
+	 */
+	u64 devId;		/*0x00 */
 
-#define MIPSNET_VERSION "2005-06-20"
+	/*
+	 * read only busy flag.
+	 * Set and cleared by the Net Device to indicate that an rx or a tx
+	 * is in progress.
+	 */
+	u32 busy;		/*0x08 */
 
-#define mipsnet_reg_address(dev, field) (dev->base_addr + field_offset(field))
+	/*
+	 * Set by the Net Device.
+	 * The device will set it once data has been received.
+	 * The value is the number of bytes that should be read from
+	 * rxDataBuffer.  The value will decrease till 0 until all the data
+	 * from rxDataBuffer has been read.
+	 */
+	u32 rxDataCount;	/*0x0c */
+#define MIPSNET_MAX_RXTX_DATACOUNT (1 << 16)
+
+	/*
+	 * Settable from the MIPS core, cleared by the Net Device.
+	 * The core should set the number of bytes it wants to send,
+	 * then it should write those bytes of data to txDataBuffer.
+	 * The device will clear txDataCount has been processed (not
+	 * necessarily sent).
+	 */
+	u32 txDataCount;	/*0x10 */
+
+	/*
+	 * Interrupt control
+	 *
+	 * Used to clear the interrupted generated by this dev.
+	 * Write a 1 to clear the interrupt. (except bit31).
+	 *
+	 * Bit0 is set if it was a tx-done interrupt.
+	 * Bit1 is set when new rx-data is available.
+	 *    Until this bit is cleared there will be no other RXs.
+	 *
+	 * Bit31 is used for testing, it clears after a read.
+	 *    Writing 1 to this bit will cause an interrupt to be generated.
+	 *    To clear the test interrupt, write 0 to this register.
+	 */
+	u32 interruptControl;	/*0x14 */
+#define MIPSNET_INTCTL_TXDONE     (1u << 0)
+#define MIPSNET_INTCTL_RXDONE     (1u << 1)
+#define MIPSNET_INTCTL_TESTBIT    (1u << 31)
+
+	/*
+	 * Readonly core-specific interrupt info for the device to signal
+	 * the core. The meaning of the contents of this field might change.
+	 */
+	/* XXX: the whole memIntf interrupt scheme is messy: the device
+	 * should have no control what so ever of what VPE/register set is
+	 * being used.
+	 * The MemIntf should only expose interrupt lines, and something in
+	 * the config should be responsible for the line<->core/vpe bindings.
+	 */
+	u32 interruptInfo;	/*0x18 */
+
+	/*
+	 * This is where the received data is read out.
+	 * There is more data to read until rxDataReady is 0.
+	 * Only 1 byte at this regs offset is used.
+	 */
+	u32 rxDataBuffer;	/*0x1c */
+
+	/*
+	 * This is where the data to transmit is written.
+	 * Data should be written for the amount specified in the
+	 * txDataCount register.
+	 * Only 1 byte at this regs offset is used.
+	 */
+	u32 txDataBuffer;	/*0x20 */
+};
+
+#define regaddr(dev, field) \
+  (dev->base_addr + offsetof(struct mipsnet_regs, field))
 
 static char mipsnet_string[] = "mipsnet";
 
@@ -29,32 +109,27 @@ static char mipsnet_string[] = "mipsnet";
 static int ioiocpy_frommipsnet(struct net_device *dev, unsigned char *kdata,
 			int len)
 {
-	uint32_t available_len = inl(mipsnet_reg_address(dev, rxDataCount));
-
-	if (available_len < len)
-		return -EFAULT;
-
 	for (; len > 0; len--, kdata++)
-		*kdata = inb(mipsnet_reg_address(dev, rxDataBuffer));
+		*kdata = inb(regaddr(dev, rxDataBuffer));
 
-	return inl(mipsnet_reg_address(dev, rxDataCount));
+	return inl(regaddr(dev, rxDataCount));
 }
 
-static inline ssize_t mipsnet_put_todevice(struct net_device *dev,
+static inline void mipsnet_put_todevice(struct net_device *dev,
 	struct sk_buff *skb)
 {
 	int count_to_go = skb->len;
 	char *buf_ptr = skb->data;
 
-	outl(skb->len, mipsnet_reg_address(dev, txDataCount));
+	outl(skb->len, regaddr(dev, txDataCount));
 
 	for (; count_to_go; buf_ptr++, count_to_go--)
-		outb(*buf_ptr, mipsnet_reg_address(dev, txDataBuffer));
+		outb(*buf_ptr, regaddr(dev, txDataBuffer));
 
 	dev->stats.tx_packets++;
 	dev->stats.tx_bytes += skb->len;
 
-	return skb->len;
+	dev_kfree_skb(skb);
 }
 
 static int mipsnet_xmit(struct sk_buff *skb, struct net_device *dev)
@@ -69,18 +144,20 @@ static int mipsnet_xmit(struct sk_buff *skb, struct net_device *dev)
 	return 0;
 }
 
-static inline ssize_t mipsnet_get_fromdev(struct net_device *dev, size_t count)
+static inline ssize_t mipsnet_get_fromdev(struct net_device *dev, size_t len)
 {
 	struct sk_buff *skb;
-	size_t len = count;
 
-	skb = alloc_skb(len + 2, GFP_KERNEL);
+	if (!len)
+		return len;
+
+	skb = dev_alloc_skb(len + NET_IP_ALIGN);
 	if (!skb) {
 		dev->stats.rx_dropped++;
 		return -ENOMEM;
 	}
 
-	skb_reserve(skb, 2);
+	skb_reserve(skb, NET_IP_ALIGN);
 	if (ioiocpy_frommipsnet(dev, skb_put(skb, len), len))
 		return -EFAULT;
 
@@ -92,50 +169,42 @@ static inline ssize_t mipsnet_get_fromdev(struct net_device *dev, size_t count)
 	dev->stats.rx_packets++;
 	dev->stats.rx_bytes += len;
 
-	return count;
+	return len;
 }
 
 static irqreturn_t mipsnet_interrupt(int irq, void *dev_id)
 {
 	struct net_device *dev = dev_id;
-
-	irqreturn_t retval = IRQ_NONE;
-	uint64_t interruptFlags;
-
-	if (irq == dev->irq) {
-		retval = IRQ_HANDLED;
-
-		interruptFlags =
-		    inl(mipsnet_reg_address(dev, interruptControl));
-
-		if (interruptFlags & MIPSNET_INTCTL_TXDONE) {
-			outl(MIPSNET_INTCTL_TXDONE,
-			     mipsnet_reg_address(dev, interruptControl));
-			/* only one packet at a time, we are done. */
-			netif_wake_queue(dev);
-		} else if (interruptFlags & MIPSNET_INTCTL_RXDONE) {
-			mipsnet_get_fromdev(dev,
-				    inl(mipsnet_reg_address(dev, rxDataCount)));
-			outl(MIPSNET_INTCTL_RXDONE,
-			     mipsnet_reg_address(dev, interruptControl));
-
-		} else if (interruptFlags & MIPSNET_INTCTL_TESTBIT) {
-			/*
-			 * TESTBIT is cleared on read.
-			 * And takes effect after a write with 0
-			 */
-			outl(0, mipsnet_reg_address(dev, interruptControl));
-		} else {
-			/* Maybe shared IRQ, just ignore, no clearing. */
-			retval = IRQ_NONE;
-		}
-
-	} else {
-		printk(KERN_INFO "%s: %s(): irq %d for unknown device\n",
-		       dev->name, __FUNCTION__, irq);
-		retval = IRQ_NONE;
+	u32 int_flags;
+	irqreturn_t ret = IRQ_NONE;
+
+	if (irq != dev->irq)
+		goto out_badirq;
+
+	/* TESTBIT is cleared on read. */
+	int_flags = inl(regaddr(dev, interruptControl));
+	if (int_flags & MIPSNET_INTCTL_TESTBIT) {
+		/* TESTBIT takes effect after a write with 0. */
+		outl(0, regaddr(dev, interruptControl));
+		ret = IRQ_HANDLED;
+	} else if (int_flags & MIPSNET_INTCTL_TXDONE) {
+		/* Only one packet at a time, we are done. */
+		dev->stats.tx_packets++;
+		netif_wake_queue(dev);
+		outl(MIPSNET_INTCTL_TXDONE,
+		     regaddr(dev, interruptControl));
+		ret = IRQ_HANDLED;
+	} else if (int_flags & MIPSNET_INTCTL_RXDONE) {
+		mipsnet_get_fromdev(dev, inl(regaddr(dev, rxDataCount)));
+		outl(MIPSNET_INTCTL_RXDONE, regaddr(dev, interruptControl));
+		ret = IRQ_HANDLED;
 	}
-	return retval;
+	return ret;
+
+out_badirq:
+	printk(KERN_INFO "%s: %s(): irq %d for unknown device\n",
+	       dev->name, __FUNCTION__, irq);
+	return ret;
 }
 
 static int mipsnet_open(struct net_device *dev)
@@ -144,18 +213,15 @@ static int mipsnet_open(struct net_device *dev)
 
 	err = request_irq(dev->irq, &mipsnet_interrupt,
 			  IRQF_SHARED, dev->name, (void *) dev);
-
 	if (err) {
-		release_region(dev->base_addr, MIPSNET_IO_EXTENT);
+		release_region(dev->base_addr, sizeof(struct mipsnet_regs));
 		return err;
 	}
 
 	netif_start_queue(dev);
 
 	/* test interrupt handler */
-	outl(MIPSNET_INTCTL_TESTBIT,
-	     mipsnet_reg_address(dev, interruptControl));
-
+	outl(MIPSNET_INTCTL_TESTBIT, regaddr(dev, interruptControl));
 
 	return 0;
 }
@@ -163,7 +229,7 @@ static int mipsnet_open(struct net_device *dev)
 static int mipsnet_close(struct net_device *dev)
 {
 	netif_stop_queue(dev);
-
+	free_irq(dev->irq, dev);
 	return 0;
 }
 
@@ -194,10 +260,11 @@ static int __init mipsnet_probe(struct device *dev)
 	 */
 	netdev->base_addr = 0x4200;
 	netdev->irq = MIPS_CPU_IRQ_BASE + MIPSCPU_INT_MB0 +
-		      inl(mipsnet_reg_address(netdev, interruptInfo));
+		      inl(regaddr(netdev, interruptInfo));
 
 	/* Get the io region now, get irq on open() */
-	if (!request_region(netdev->base_addr, MIPSNET_IO_EXTENT, "mipsnet")) {
+	if (!request_region(netdev->base_addr, sizeof(struct mipsnet_regs),
+			    "mipsnet")) {
 		err = -EBUSY;
 		goto out_free_netdev;
 	}
@@ -217,7 +284,7 @@ static int __init mipsnet_probe(struct device *dev)
 	return 0;
 
 out_free_region:
-	release_region(netdev->base_addr, MIPSNET_IO_EXTENT);
+	release_region(netdev->base_addr, sizeof(struct mipsnet_regs));
 
 out_free_netdev:
 	free_netdev(netdev);
@@ -231,7 +298,7 @@ static int __devexit mipsnet_device_remove(struct device *device)
 	struct net_device *dev = dev_get_drvdata(device);
 
 	unregister_netdev(dev);
-	release_region(dev->base_addr, MIPSNET_IO_EXTENT);
+	release_region(dev->base_addr, sizeof(struct mipsnet_regs));
 	free_netdev(dev);
 	dev_set_drvdata(device, NULL);