Device tree aware EMAC driver

Based on BenH's earlier work, this is a new version of the EMAC driver
for the built-in ethernet found on PowerPC 4xx embedded CPUs.  The
same ASIC is also found in the Axon bridge chip.  This new version is
designed to work in the arch/powerpc tree, using the device tree to
probe the device, rather than the old and ugly arch/ppc OCP layer.

This driver is designed to sit alongside the old driver (that lies in
drivers/net/ibm_emac and this one in drivers/net/ibm_newemac).  The
old driver is left in place to support arch/ppc until arch/ppc itself
reaches its final demise (not too long now, with luck).

This driver still has a number of things that could do with cleaning
up, but I think they can be fixed up after merging.  Specifically:
	- Should be adjusted to properly use the dma mapping API.
Axon needs this.
	- Probe logic needs reworking, in conjuction with the general
probing code for of_platform devices.  The dependencies here between
EMAC, MAL, ZMII etc. make this complicated.  At present, it usually
works, because we initialize and register the sub-drivers before the
EMAC driver itself, and (being in driver code) runs after the devices
themselves have been instantiated from the device tree.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/ibm_newemac/tah.c

@@ -0,0 +1,173 @@
+/*
+ * drivers/net/ibm_newemac/tah.c
+ *
+ * Driver for PowerPC 4xx on-chip ethernet controller, TAH support.
+ *
+ * Copyright 2004 MontaVista Software, Inc.
+ * Matt Porter <mporter@kernel.crashing.org>
+ *
+ * Copyright (c) 2005 Eugene Surovegin <ebs@ebshome.net>
+ *
+ * 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.
+ */
+#include <asm/io.h>
+
+#include "emac.h"
+#include "core.h"
+
+int __devinit tah_attach(struct of_device *ofdev, int channel)
+{
+	struct tah_instance *dev = dev_get_drvdata(&ofdev->dev);
+
+	mutex_lock(&dev->lock);
+	/* Reset has been done at probe() time... nothing else to do for now */
+	++dev->users;
+	mutex_unlock(&dev->lock);
+
+	return 0;
+}
+
+void __devexit tah_detach(struct of_device *ofdev, int channel)
+{
+	struct tah_instance *dev = dev_get_drvdata(&ofdev->dev);
+
+	mutex_lock(&dev->lock);
+	--dev->users;
+	mutex_unlock(&dev->lock);
+}
+
+void tah_reset(struct of_device *ofdev)
+{
+	struct tah_instance *dev = dev_get_drvdata(&ofdev->dev);
+	struct tah_regs *p = dev->base;
+	int n;
+
+	/* Reset TAH */
+	out_be32(&p->mr, TAH_MR_SR);
+	n = 100;
+	while ((in_be32(&p->mr) & TAH_MR_SR) && n)
+		--n;
+
+	if (unlikely(!n))
+		printk(KERN_ERR "%s: reset timeout\n", ofdev->node->full_name);
+
+	/* 10KB TAH TX FIFO accomodates the max MTU of 9000 */
+	out_be32(&p->mr,
+		 TAH_MR_CVR | TAH_MR_ST_768 | TAH_MR_TFS_10KB | TAH_MR_DTFP |
+		 TAH_MR_DIG);
+}
+
+int tah_get_regs_len(struct of_device *ofdev)
+{
+	return sizeof(struct emac_ethtool_regs_subhdr) +
+		sizeof(struct tah_regs);
+}
+
+void *tah_dump_regs(struct of_device *ofdev, void *buf)
+{
+	struct tah_instance *dev = dev_get_drvdata(&ofdev->dev);
+	struct emac_ethtool_regs_subhdr *hdr = buf;
+	struct tah_regs *regs = (struct tah_regs *)(hdr + 1);
+
+	hdr->version = 0;
+	hdr->index = 0; /* for now, are there chips with more than one
+			 * zmii ? if yes, then we'll add a cell_index
+			 * like we do for emac
+			 */
+	memcpy_fromio(regs, dev->base, sizeof(struct tah_regs));
+	return regs + 1;
+}
+
+static int __devinit tah_probe(struct of_device *ofdev,
+			       const struct of_device_id *match)
+{
+	struct device_node *np = ofdev->node;
+	struct tah_instance *dev;
+	struct resource regs;
+	int rc;
+
+	rc = -ENOMEM;
+	dev = kzalloc(sizeof(struct tah_instance), GFP_KERNEL);
+	if (dev == NULL) {
+		printk(KERN_ERR "%s: could not allocate TAH device!\n",
+		       np->full_name);
+		goto err_gone;
+	}
+
+	mutex_init(&dev->lock);
+	dev->ofdev = ofdev;
+
+	rc = -ENXIO;
+	if (of_address_to_resource(np, 0, &regs)) {
+		printk(KERN_ERR "%s: Can't get registers address\n",
+		       np->full_name);
+		goto err_free;
+	}
+
+	rc = -ENOMEM;
+	dev->base = (struct tah_regs *)ioremap(regs.start,
+					       sizeof(struct tah_regs));
+	if (dev->base == NULL) {
+		printk(KERN_ERR "%s: Can't map device registers!\n",
+		       np->full_name);
+		goto err_free;
+	}
+
+	/* Initialize TAH and enable IPv4 checksum verification, no TSO yet */
+	tah_reset(ofdev);
+
+	printk(KERN_INFO
+	       "TAH %s initialized\n", ofdev->node->full_name);
+	wmb();
+	dev_set_drvdata(&ofdev->dev, dev);
+
+	return 0;
+
+ err_free:
+	kfree(dev);
+ err_gone:
+	return rc;
+}
+
+static int __devexit tah_remove(struct of_device *ofdev)
+{
+	struct tah_instance *dev = dev_get_drvdata(&ofdev->dev);
+
+	dev_set_drvdata(&ofdev->dev, NULL);
+
+	WARN_ON(dev->users != 0);
+
+	iounmap(dev->base);
+	kfree(dev);
+
+	return 0;
+}
+
+static struct of_device_id tah_match[] =
+{
+	{
+		.type		= "tah",
+	},
+	{},
+};
+
+static struct of_platform_driver tah_driver = {
+	.name = "emac-tah",
+	.match_table = tah_match,
+
+	.probe = tah_probe,
+	.remove = tah_remove,
+};
+
+int __init tah_init(void)
+{
+	return of_register_platform_driver(&tah_driver);
+}
+
+void tah_exit(void)
+{
+	of_unregister_platform_driver(&tah_driver);
+}