drivers/i2c/busses/i2c-powermac.c - kernel/common - Git at Google

 /*
     i2c Support for Apple SMU Controller

     Copyright (c) 2005 Benjamin Herrenschmidt, IBM Corp.
                        <[email protected]>

     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., 675 Mass Ave, Cambridge, MA 02139, USA.

 */

 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/types.h>
 #include <linux/i2c.h>
 #include <linux/device.h>
 #include <linux/platform_device.h>
 #include <linux/of_irq.h>
 #include <asm/prom.h>
 #include <asm/pmac_low_i2c.h>

 MODULE_AUTHOR("Benjamin Herrenschmidt <[email protected]>");
 MODULE_DESCRIPTION("I2C driver for Apple PowerMac");
 MODULE_LICENSE("GPL");

 /*
  * SMBUS-type transfer entrypoint
  */
 static s32 i2c_powermac_smbus_xfer(	struct i2c_adapter*	adap,
 					u16			addr,
 					unsigned short		flags,
 					char			read_write,
 					u8			command,
 					int			size,
 					union i2c_smbus_data*	data)
 {
 	struct pmac_i2c_bus	*bus = i2c_get_adapdata(adap);
 	int			rc = 0;
 	int			read = (read_write == I2C_SMBUS_READ);
 	int			addrdir = (addr << 1) | read;
 	int			mode, subsize, len;
 	u32			subaddr;
 	u8			*buf;
 	u8			local[2];

 	if (size == I2C_SMBUS_QUICK || size == I2C_SMBUS_BYTE) {
 		mode = pmac_i2c_mode_std;
 		subsize = 0;
 		subaddr = 0;
 	} else {
 		mode = read ? pmac_i2c_mode_combined : pmac_i2c_mode_stdsub;
 		subsize = 1;
 		subaddr = command;
 	}

 	switch (size) {
         case I2C_SMBUS_QUICK:
 		buf = NULL;
 		len = 0;
 	    	break;
         case I2C_SMBUS_BYTE:
         case I2C_SMBUS_BYTE_DATA:
 		buf = &data->byte;
 		len = 1;
 	    	break;
         case I2C_SMBUS_WORD_DATA:
 		if (!read) {
 			local[0] = data->word & 0xff;
 			local[1] = (data->word >> 8) & 0xff;
 		}
 		buf = local;
 		len = 2;
 	    	break;

 	/* Note that these are broken vs. the expected smbus API where
 	 * on reads, the length is actually returned from the function,
 	 * but I think the current API makes no sense and I don't want
 	 * any driver that I haven't verified for correctness to go
 	 * anywhere near a pmac i2c bus anyway ...
 	 *
 	 * I'm also not completely sure what kind of phases to do between
 	 * the actual command and the data (what I am _supposed_ to do that
 	 * is). For now, I assume writes are a single stream and reads have
 	 * a repeat start/addr phase (but not stop in between)
 	 */
         case I2C_SMBUS_BLOCK_DATA:
 		buf = data->block;
 		len = data->block[0] + 1;
 		break;
 	case I2C_SMBUS_I2C_BLOCK_DATA:
 		buf = &data->block[1];
 		len = data->block[0];
 		break;

         default:
 		return -EINVAL;
 	}

 	rc = pmac_i2c_open(bus, 0);
 	if (rc) {
 		dev_err(&adap->dev, "Failed to open I2C, err %d\n", rc);
 		return rc;
 	}

 	rc = pmac_i2c_setmode(bus, mode);
 	if (rc) {
 		dev_err(&adap->dev, "Failed to set I2C mode %d, err %d\n",
 			mode, rc);
 		goto bail;
 	}

 	rc = pmac_i2c_xfer(bus, addrdir, subsize, subaddr, buf, len);
 	if (rc) {
 		if (rc == -ENXIO)
 			dev_dbg(&adap->dev,
 				"I2C transfer at 0x%02x failed, size %d, "
 				"err %d\n", addrdir >> 1, size, rc);
 		else
 			dev_err(&adap->dev,
 				"I2C transfer at 0x%02x failed, size %d, "
 				"err %d\n", addrdir >> 1, size, rc);
 		goto bail;
 	}

 	if (size == I2C_SMBUS_WORD_DATA && read) {
 		data->word = ((u16)local[1]) << 8;
 		data->word |= local[0];
 	}

  bail:
 	pmac_i2c_close(bus);
 	return rc;
 }

 /*
  * Generic i2c master transfer entrypoint. This driver only support single
  * messages (for "lame i2c" transfers). Anything else should use the smbus
  * entry point
  */
 static int i2c_powermac_master_xfer(	struct i2c_adapter *adap,
 					struct i2c_msg *msgs,
 					int num)
 {
 	struct pmac_i2c_bus	*bus = i2c_get_adapdata(adap);
 	int			rc = 0;
 	int			read;
 	int			addrdir;

 	if (num != 1) {
 		dev_err(&adap->dev,
 			"Multi-message I2C transactions not supported\n");
 		return -EOPNOTSUPP;
 	}

 	if (msgs->flags & I2C_M_TEN)
 		return -EINVAL;
 	read = (msgs->flags & I2C_M_RD) != 0;
 	addrdir = (msgs->addr << 1) | read;

 	rc = pmac_i2c_open(bus, 0);
 	if (rc) {
 		dev_err(&adap->dev, "Failed to open I2C, err %d\n", rc);
 		return rc;
 	}
 	rc = pmac_i2c_setmode(bus, pmac_i2c_mode_std);
 	if (rc) {
 		dev_err(&adap->dev, "Failed to set I2C mode %d, err %d\n",
 			pmac_i2c_mode_std, rc);
 		goto bail;
 	}
 	rc = pmac_i2c_xfer(bus, addrdir, 0, 0, msgs->buf, msgs->len);
 	if (rc < 0) {
 		if (rc == -ENXIO)
 			dev_dbg(&adap->dev, "I2C %s 0x%02x failed, err %d\n",
 				addrdir & 1 ? "read from" : "write to",
 				addrdir >> 1, rc);
 		else
 			dev_err(&adap->dev, "I2C %s 0x%02x failed, err %d\n",
 				addrdir & 1 ? "read from" : "write to",
 				addrdir >> 1, rc);
 	}
  bail:
 	pmac_i2c_close(bus);
 	return rc < 0 ? rc : 1;
 }

 static u32 i2c_powermac_func(struct i2c_adapter * adapter)
 {
 	return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
 		I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
 		I2C_FUNC_SMBUS_BLOCK_DATA | I2C_FUNC_I2C;
 }

 /* For now, we only handle smbus */
 static const struct i2c_algorithm i2c_powermac_algorithm = {
 	.smbus_xfer	= i2c_powermac_smbus_xfer,
 	.master_xfer	= i2c_powermac_master_xfer,
 	.functionality	= i2c_powermac_func,
 };


 static int i2c_powermac_remove(struct platform_device *dev)
 {
 	struct i2c_adapter	*adapter = platform_get_drvdata(dev);

 	i2c_del_adapter(adapter);
 	memset(adapter, 0, sizeof(*adapter));

 	return 0;
 }

 static u32 i2c_powermac_get_addr(struct i2c_adapter *adap,
 					   struct pmac_i2c_bus *bus,
 					   struct device_node *node)
 {
 	const __be32 *prop;
 	int len;

 	/* First check for valid "reg" */
 	prop = of_get_property(node, "reg", &len);
 	if (prop && (len >= sizeof(int)))
 		return (be32_to_cpup(prop) & 0xff) >> 1;

 	/* Then check old-style "i2c-address" */
 	prop = of_get_property(node, "i2c-address", &len);
 	if (prop && (len >= sizeof(int)))
 		return (be32_to_cpup(prop) & 0xff) >> 1;

 	/* Now handle some devices with missing "reg" properties */
 	if (!strcmp(node->name, "cereal"))
 		return 0x60;
 	else if (!strcmp(node->name, "deq"))
 		return 0x34;

 	dev_warn(&adap->dev, "No i2c address for %s\n", node->full_name);

 	return 0xffffffff;
 }

 static void i2c_powermac_create_one(struct i2c_adapter *adap,
 					      const char *type,
 					      u32 addr)
 {
 	struct i2c_board_info info = {};
 	struct i2c_client *newdev;

 	strncpy(info.type, type, sizeof(info.type));
 	info.addr = addr;
 	newdev = i2c_new_device(adap, &info);
 	if (!newdev)
 		dev_err(&adap->dev,
 			"i2c-powermac: Failure to register missing %s\n",
 			type);
 }

 static void i2c_powermac_add_missing(struct i2c_adapter *adap,
 					       struct pmac_i2c_bus *bus,
 					       bool found_onyx)
 {
 	struct device_node *busnode = pmac_i2c_get_bus_node(bus);
 	int rc;

 	/* Check for the onyx audio codec */
 #define ONYX_REG_CONTROL		67
 	if (of_device_is_compatible(busnode, "k2-i2c") && !found_onyx) {
 		union i2c_smbus_data data;

 		rc = i2c_smbus_xfer(adap, 0x46, 0, I2C_SMBUS_READ,
 				    ONYX_REG_CONTROL, I2C_SMBUS_BYTE_DATA,
 				    &data);
 		if (rc >= 0)
 			i2c_powermac_create_one(adap, "MAC,pcm3052", 0x46);

 		rc = i2c_smbus_xfer(adap, 0x47, 0, I2C_SMBUS_READ,
 				    ONYX_REG_CONTROL, I2C_SMBUS_BYTE_DATA,
 				    &data);
 		if (rc >= 0)
 			i2c_powermac_create_one(adap, "MAC,pcm3052", 0x47);
 	}
 }

 static bool i2c_powermac_get_type(struct i2c_adapter *adap,
 					    struct device_node *node,
 					    u32 addr, char *type, int type_size)
 {
 	char tmp[16];

 	/* Note: we to _NOT_ want the standard
 	 * i2c drivers to match with any of our powermac stuff
 	 * unless they have been specifically modified to handle
 	 * it on a case by case basis. For example, for thermal
 	 * control, things like lm75 etc... shall match with their
 	 * corresponding windfarm drivers, _NOT_ the generic ones,
 	 * so we force a prefix of AAPL, onto the modalias to
 	 * make that happen
 	 */

 	/* First try proper modalias */
 	if (of_modalias_node(node, tmp, sizeof(tmp)) >= 0) {
 		snprintf(type, type_size, "MAC,%s", tmp);
 		return true;
 	}

 	/* Now look for known workarounds */
 	if (!strcmp(node->name, "deq")) {
 		/* Apple uses address 0x34 for TAS3001 and 0x35 for TAS3004 */
 		if (addr == 0x34) {
 			snprintf(type, type_size, "MAC,tas3001");
 			return true;
 		} else if (addr == 0x35) {
 			snprintf(type, type_size, "MAC,tas3004");
 			return true;
 		}
 	}

 	dev_err(&adap->dev, "i2c-powermac: modalias failure"
 		" on %s\n", node->full_name);
 	return false;
 }

 static void i2c_powermac_register_devices(struct i2c_adapter *adap,
 						    struct pmac_i2c_bus *bus)
 {
 	struct i2c_client *newdev;
 	struct device_node *node;
 	bool found_onyx = 0;

 	/*
 	 * In some cases we end up with the via-pmu node itself, in this
 	 * case we skip this function completely as the device-tree will
 	 * not contain anything useful.
 	 */
 	if (!strcmp(adap->dev.of_node->name, "via-pmu"))
 		return;

 	for_each_child_of_node(adap->dev.of_node, node) {
 		struct i2c_board_info info = {};
 		u32 addr;

 		/* Get address & channel */
 		addr = i2c_powermac_get_addr(adap, bus, node);
 		if (addr == 0xffffffff)
 			continue;

 		/* Multibus setup, check channel */
 		if (!pmac_i2c_match_adapter(node, adap))
 			continue;

 		dev_dbg(&adap->dev, "i2c-powermac: register %s\n",
 			node->full_name);

 		/*
 		 * Keep track of some device existence to handle
 		 * workarounds later.
 		 */
 		if (of_device_is_compatible(node, "pcm3052"))
 			found_onyx = true;

 		/* Make up a modalias */
 		if (!i2c_powermac_get_type(adap, node, addr,
 					   info.type, sizeof(info.type))) {
 			continue;
 		}

 		/* Fill out the rest of the info structure */
 		info.addr = addr;
 		info.irq = irq_of_parse_and_map(node, 0);
 		info.of_node = of_node_get(node);

 		newdev = i2c_new_device(adap, &info);
 		if (!newdev) {
 			dev_err(&adap->dev, "i2c-powermac: Failure to register"
 				" %s\n", node->full_name);
 			of_node_put(node);
 			/* We do not dispose of the interrupt mapping on
 			 * purpose. It's not necessary (interrupt cannot be
 			 * re-used) and somebody else might have grabbed it
 			 * via direct DT lookup so let's not bother
 			 */
 			continue;
 		}
 	}

 	/* Additional workarounds */
 	i2c_powermac_add_missing(adap, bus, found_onyx);
 }

 static int i2c_powermac_probe(struct platform_device *dev)
 {
 	struct pmac_i2c_bus *bus = dev_get_platdata(&dev->dev);
 	struct device_node *parent = NULL;
 	struct i2c_adapter *adapter;
 	const char *basename;
 	int rc;

 	if (bus == NULL)
 		return -EINVAL;
 	adapter = pmac_i2c_get_adapter(bus);

 	/* Ok, now we need to make up a name for the interface that will
 	 * match what we used to do in the past, that is basically the
 	 * controller's parent device node for keywest. PMU didn't have a
 	 * naming convention and SMU has a different one
 	 */
 	switch(pmac_i2c_get_type(bus)) {
 	case pmac_i2c_bus_keywest:
 		parent = of_get_parent(pmac_i2c_get_controller(bus));
 		if (parent == NULL)
 			return -EINVAL;
 		basename = parent->name;
 		break;
 	case pmac_i2c_bus_pmu:
 		basename = "pmu";
 		break;
 	case pmac_i2c_bus_smu:
 		/* This is not what we used to do but I'm fixing drivers at
 		 * the same time as this change
 		 */
 		basename = "smu";
 		break;
 	default:
 		return -EINVAL;
 	}
 	snprintf(adapter->name, sizeof(adapter->name), "%s %d", basename,
 		 pmac_i2c_get_channel(bus));
 	of_node_put(parent);

 	platform_set_drvdata(dev, adapter);
 	adapter->algo = &i2c_powermac_algorithm;
 	i2c_set_adapdata(adapter, bus);
 	adapter->dev.parent = &dev->dev;

 	/* Clear of_node to skip automatic registration of i2c child nodes */
 	adapter->dev.of_node = NULL;
 	rc = i2c_add_adapter(adapter);
 	if (rc) {
 		printk(KERN_ERR "i2c-powermac: Adapter %s registration "
 		       "failed\n", adapter->name);
 		memset(adapter, 0, sizeof(*adapter));
 		return rc;
 	}

 	printk(KERN_INFO "PowerMac i2c bus %s registered\n", adapter->name);

 	/* Use custom child registration due to Apple device-tree funkyness */
 	adapter->dev.of_node = dev->dev.of_node;
 	i2c_powermac_register_devices(adapter, bus);

 	return 0;
 }

 static struct platform_driver i2c_powermac_driver = {
 	.probe = i2c_powermac_probe,
 	.remove = i2c_powermac_remove,
 	.driver = {
 		.name = "i2c-powermac",
 		.bus = &platform_bus_type,
 	},
 };

 module_platform_driver(i2c_powermac_driver);

 MODULE_ALIAS("platform:i2c-powermac");
	/*
	i2c Support for Apple SMU Controller

	Copyright (c) 2005 Benjamin Herrenschmidt, IBM Corp.
	<[email protected]>

	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., 675 Mass Ave, Cambridge, MA 02139, USA.

	*/

	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <linux/types.h>
	#include <linux/i2c.h>
	#include <linux/device.h>
	#include <linux/platform_device.h>
	#include <linux/of_irq.h>
	#include <asm/prom.h>
	#include <asm/pmac_low_i2c.h>

	MODULE_AUTHOR("Benjamin Herrenschmidt <[email protected]>");
	MODULE_DESCRIPTION("I2C driver for Apple PowerMac");
	MODULE_LICENSE("GPL");

	/*
	* SMBUS-type transfer entrypoint
	*/
	static s32 i2c_powermac_smbus_xfer( struct i2c_adapter* adap,
	u16 addr,
	unsigned short flags,
	char read_write,
	u8 command,
	int size,
	union i2c_smbus_data* data)
	{
	struct pmac_i2c_bus *bus = i2c_get_adapdata(adap);
	int rc = 0;
	int read = (read_write == I2C_SMBUS_READ);
	int addrdir = (addr << 1) \| read;
	int mode, subsize, len;
	u32 subaddr;
	u8 *buf;
	u8 local[2];

	if (size == I2C_SMBUS_QUICK \|\| size == I2C_SMBUS_BYTE) {
	mode = pmac_i2c_mode_std;
	subsize = 0;
	subaddr = 0;
	} else {
	mode = read ? pmac_i2c_mode_combined : pmac_i2c_mode_stdsub;
	subsize = 1;
	subaddr = command;
	}

	switch (size) {
	case I2C_SMBUS_QUICK:
	buf = NULL;
	len = 0;
	break;
	case I2C_SMBUS_BYTE:
	case I2C_SMBUS_BYTE_DATA:
	buf = &data->byte;
	len = 1;
	break;
	case I2C_SMBUS_WORD_DATA:
	if (!read) {
	local[0] = data->word & 0xff;
	local[1] = (data->word >> 8) & 0xff;
	}
	buf = local;
	len = 2;
	break;

	/* Note that these are broken vs. the expected smbus API where
	* on reads, the length is actually returned from the function,
	* but I think the current API makes no sense and I don't want
	* any driver that I haven't verified for correctness to go
	* anywhere near a pmac i2c bus anyway ...
	*
	* I'm also not completely sure what kind of phases to do between
	* the actual command and the data (what I am _supposed_ to do that
	* is). For now, I assume writes are a single stream and reads have
	* a repeat start/addr phase (but not stop in between)
	*/
	case I2C_SMBUS_BLOCK_DATA:
	buf = data->block;
	len = data->block[0] + 1;
	break;
	case I2C_SMBUS_I2C_BLOCK_DATA:
	buf = &data->block[1];
	len = data->block[0];
	break;

	default:
	return -EINVAL;
	}

	rc = pmac_i2c_open(bus, 0);
	if (rc) {
	dev_err(&adap->dev, "Failed to open I2C, err %d\n", rc);
	return rc;
	}

	rc = pmac_i2c_setmode(bus, mode);
	if (rc) {
	dev_err(&adap->dev, "Failed to set I2C mode %d, err %d\n",
	mode, rc);
	goto bail;
	}

	rc = pmac_i2c_xfer(bus, addrdir, subsize, subaddr, buf, len);
	if (rc) {
	if (rc == -ENXIO)
	dev_dbg(&adap->dev,
	"I2C transfer at 0x%02x failed, size %d, "
	"err %d\n", addrdir >> 1, size, rc);
	else
	dev_err(&adap->dev,
	"I2C transfer at 0x%02x failed, size %d, "
	"err %d\n", addrdir >> 1, size, rc);
	goto bail;
	}

	if (size == I2C_SMBUS_WORD_DATA && read) {
	data->word = ((u16)local[1]) << 8;
	data->word \|= local[0];
	}

	bail:
	pmac_i2c_close(bus);
	return rc;
	}

	/*
	* Generic i2c master transfer entrypoint. This driver only support single
	* messages (for "lame i2c" transfers). Anything else should use the smbus
	* entry point
	*/
	static int i2c_powermac_master_xfer( struct i2c_adapter *adap,
	struct i2c_msg *msgs,
	int num)
	{
	struct pmac_i2c_bus *bus = i2c_get_adapdata(adap);
	int rc = 0;
	int read;
	int addrdir;

	if (num != 1) {
	dev_err(&adap->dev,
	"Multi-message I2C transactions not supported\n");
	return -EOPNOTSUPP;
	}

	if (msgs->flags & I2C_M_TEN)
	return -EINVAL;
	read = (msgs->flags & I2C_M_RD) != 0;
	addrdir = (msgs->addr << 1) \| read;

	rc = pmac_i2c_open(bus, 0);
	if (rc) {
	dev_err(&adap->dev, "Failed to open I2C, err %d\n", rc);
	return rc;
	}
	rc = pmac_i2c_setmode(bus, pmac_i2c_mode_std);
	if (rc) {
	dev_err(&adap->dev, "Failed to set I2C mode %d, err %d\n",
	pmac_i2c_mode_std, rc);
	goto bail;
	}
	rc = pmac_i2c_xfer(bus, addrdir, 0, 0, msgs->buf, msgs->len);
	if (rc < 0) {
	if (rc == -ENXIO)
	dev_dbg(&adap->dev, "I2C %s 0x%02x failed, err %d\n",
	addrdir & 1 ? "read from" : "write to",
	addrdir >> 1, rc);
	else
	dev_err(&adap->dev, "I2C %s 0x%02x failed, err %d\n",
	addrdir & 1 ? "read from" : "write to",
	addrdir >> 1, rc);
	}
	bail:
	pmac_i2c_close(bus);
	return rc < 0 ? rc : 1;
	}

	static u32 i2c_powermac_func(struct i2c_adapter * adapter)
	{
	return I2C_FUNC_SMBUS_QUICK \| I2C_FUNC_SMBUS_BYTE \|
	I2C_FUNC_SMBUS_BYTE_DATA \| I2C_FUNC_SMBUS_WORD_DATA \|
	I2C_FUNC_SMBUS_BLOCK_DATA \| I2C_FUNC_I2C;
	}

	/* For now, we only handle smbus */
	static const struct i2c_algorithm i2c_powermac_algorithm = {
	.smbus_xfer = i2c_powermac_smbus_xfer,
	.master_xfer = i2c_powermac_master_xfer,
	.functionality = i2c_powermac_func,
	};


	static int i2c_powermac_remove(struct platform_device *dev)
	{
	struct i2c_adapter *adapter = platform_get_drvdata(dev);

	i2c_del_adapter(adapter);
	memset(adapter, 0, sizeof(*adapter));

	return 0;
	}

	static u32 i2c_powermac_get_addr(struct i2c_adapter *adap,
	struct pmac_i2c_bus *bus,
	struct device_node *node)
	{
	const __be32 *prop;
	int len;

	/* First check for valid "reg" */
	prop = of_get_property(node, "reg", &len);
	if (prop && (len >= sizeof(int)))
	return (be32_to_cpup(prop) & 0xff) >> 1;

	/* Then check old-style "i2c-address" */
	prop = of_get_property(node, "i2c-address", &len);
	if (prop && (len >= sizeof(int)))
	return (be32_to_cpup(prop) & 0xff) >> 1;

	/* Now handle some devices with missing "reg" properties */
	if (!strcmp(node->name, "cereal"))
	return 0x60;
	else if (!strcmp(node->name, "deq"))
	return 0x34;

	dev_warn(&adap->dev, "No i2c address for %s\n", node->full_name);

	return 0xffffffff;
	}

	static void i2c_powermac_create_one(struct i2c_adapter *adap,
	const char *type,
	u32 addr)
	{
	struct i2c_board_info info = {};
	struct i2c_client *newdev;

	strncpy(info.type, type, sizeof(info.type));
	info.addr = addr;
	newdev = i2c_new_device(adap, &info);
	if (!newdev)
	dev_err(&adap->dev,
	"i2c-powermac: Failure to register missing %s\n",
	type);
	}

	static void i2c_powermac_add_missing(struct i2c_adapter *adap,
	struct pmac_i2c_bus *bus,
	bool found_onyx)
	{
	struct device_node *busnode = pmac_i2c_get_bus_node(bus);
	int rc;

	/* Check for the onyx audio codec */
	#define ONYX_REG_CONTROL 67
	if (of_device_is_compatible(busnode, "k2-i2c") && !found_onyx) {
	union i2c_smbus_data data;

	rc = i2c_smbus_xfer(adap, 0x46, 0, I2C_SMBUS_READ,
	ONYX_REG_CONTROL, I2C_SMBUS_BYTE_DATA,
	&data);
	if (rc >= 0)
	i2c_powermac_create_one(adap, "MAC,pcm3052", 0x46);

	rc = i2c_smbus_xfer(adap, 0x47, 0, I2C_SMBUS_READ,
	ONYX_REG_CONTROL, I2C_SMBUS_BYTE_DATA,
	&data);
	if (rc >= 0)
	i2c_powermac_create_one(adap, "MAC,pcm3052", 0x47);
	}
	}

	static bool i2c_powermac_get_type(struct i2c_adapter *adap,
	struct device_node *node,
	u32 addr, char *type, int type_size)
	{
	char tmp[16];

	/* Note: we to _NOT_ want the standard
	* i2c drivers to match with any of our powermac stuff
	* unless they have been specifically modified to handle
	* it on a case by case basis. For example, for thermal
	* control, things like lm75 etc... shall match with their
	* corresponding windfarm drivers, _NOT_ the generic ones,
	* so we force a prefix of AAPL, onto the modalias to
	* make that happen
	*/

	/* First try proper modalias */
	if (of_modalias_node(node, tmp, sizeof(tmp)) >= 0) {
	snprintf(type, type_size, "MAC,%s", tmp);
	return true;
	}

	/* Now look for known workarounds */
	if (!strcmp(node->name, "deq")) {
	/* Apple uses address 0x34 for TAS3001 and 0x35 for TAS3004 */
	if (addr == 0x34) {
	snprintf(type, type_size, "MAC,tas3001");
	return true;
	} else if (addr == 0x35) {
	snprintf(type, type_size, "MAC,tas3004");
	return true;
	}
	}

	dev_err(&adap->dev, "i2c-powermac: modalias failure"
	" on %s\n", node->full_name);
	return false;
	}

	static void i2c_powermac_register_devices(struct i2c_adapter *adap,
	struct pmac_i2c_bus *bus)
	{
	struct i2c_client *newdev;
	struct device_node *node;
	bool found_onyx = 0;

	/*
	* In some cases we end up with the via-pmu node itself, in this
	* case we skip this function completely as the device-tree will
	* not contain anything useful.
	*/
	if (!strcmp(adap->dev.of_node->name, "via-pmu"))
	return;

	for_each_child_of_node(adap->dev.of_node, node) {
	struct i2c_board_info info = {};
	u32 addr;

	/* Get address & channel */
	addr = i2c_powermac_get_addr(adap, bus, node);
	if (addr == 0xffffffff)
	continue;

	/* Multibus setup, check channel */
	if (!pmac_i2c_match_adapter(node, adap))
	continue;

	dev_dbg(&adap->dev, "i2c-powermac: register %s\n",
	node->full_name);

	/*
	* Keep track of some device existence to handle
	* workarounds later.
	*/
	if (of_device_is_compatible(node, "pcm3052"))
	found_onyx = true;

	/* Make up a modalias */
	if (!i2c_powermac_get_type(adap, node, addr,
	info.type, sizeof(info.type))) {
	continue;
	}

	/* Fill out the rest of the info structure */
	info.addr = addr;
	info.irq = irq_of_parse_and_map(node, 0);
	info.of_node = of_node_get(node);

	newdev = i2c_new_device(adap, &info);
	if (!newdev) {
	dev_err(&adap->dev, "i2c-powermac: Failure to register"
	" %s\n", node->full_name);
	of_node_put(node);
	/* We do not dispose of the interrupt mapping on
	* purpose. It's not necessary (interrupt cannot be
	* re-used) and somebody else might have grabbed it
	* via direct DT lookup so let's not bother
	*/
	continue;
	}
	}

	/* Additional workarounds */
	i2c_powermac_add_missing(adap, bus, found_onyx);
	}

	static int i2c_powermac_probe(struct platform_device *dev)
	{
	struct pmac_i2c_bus *bus = dev_get_platdata(&dev->dev);
	struct device_node *parent = NULL;
	struct i2c_adapter *adapter;
	const char *basename;
	int rc;

	if (bus == NULL)
	return -EINVAL;
	adapter = pmac_i2c_get_adapter(bus);

	/* Ok, now we need to make up a name for the interface that will
	* match what we used to do in the past, that is basically the
	* controller's parent device node for keywest. PMU didn't have a
	* naming convention and SMU has a different one
	*/
	switch(pmac_i2c_get_type(bus)) {
	case pmac_i2c_bus_keywest:
	parent = of_get_parent(pmac_i2c_get_controller(bus));
	if (parent == NULL)
	return -EINVAL;
	basename = parent->name;
	break;
	case pmac_i2c_bus_pmu:
	basename = "pmu";
	break;
	case pmac_i2c_bus_smu:
	/* This is not what we used to do but I'm fixing drivers at
	* the same time as this change
	*/
	basename = "smu";
	break;
	default:
	return -EINVAL;
	}
	snprintf(adapter->name, sizeof(adapter->name), "%s %d", basename,
	pmac_i2c_get_channel(bus));
	of_node_put(parent);

	platform_set_drvdata(dev, adapter);
	adapter->algo = &i2c_powermac_algorithm;
	i2c_set_adapdata(adapter, bus);
	adapter->dev.parent = &dev->dev;

	/* Clear of_node to skip automatic registration of i2c child nodes */
	adapter->dev.of_node = NULL;
	rc = i2c_add_adapter(adapter);
	if (rc) {
	printk(KERN_ERR "i2c-powermac: Adapter %s registration "
	"failed\n", adapter->name);
	memset(adapter, 0, sizeof(*adapter));
	return rc;
	}

	printk(KERN_INFO "PowerMac i2c bus %s registered\n", adapter->name);

	/* Use custom child registration due to Apple device-tree funkyness */
	adapter->dev.of_node = dev->dev.of_node;
	i2c_powermac_register_devices(adapter, bus);

	return 0;
	}

	static struct platform_driver i2c_powermac_driver = {
	.probe = i2c_powermac_probe,
	.remove = i2c_powermac_remove,
	.driver = {
	.name = "i2c-powermac",
	.bus = &platform_bus_type,
	},
	};

	module_platform_driver(i2c_powermac_driver);

	MODULE_ALIAS("platform:i2c-powermac");