/*
    i2c Support for Apple SMU Controller

    Copyright (c) 2005 Benjamin Herrenschmidt, IBM Corp.
                       <benh@kernel.crashing.org>

    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/init.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <asm/prom.h>
#include <asm/pmac_low_i2c.h>

MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
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 __devexit i2c_powermac_remove(struct platform_device *dev)
{
	struct i2c_adapter	*adapter = platform_get_drvdata(dev);
	int			rc;

	rc = i2c_del_adapter(adapter);
	/* We aren't that prepared to deal with this... */
	if (rc)
		printk(KERN_WARNING
		       "i2c-powermac.c: Failed to remove bus %s !\n",
		       adapter->name);
	platform_set_drvdata(dev, NULL);
	memset(adapter, 0, sizeof(*adapter));

	return 0;
}

static void __devinit i2c_powermac_register_devices(struct i2c_adapter *adap,
						    struct pmac_i2c_bus *bus)
{
	struct i2c_client *newdev;
	struct device_node *node;

	for_each_child_of_node(adap->dev.of_node, node) {
		struct i2c_board_info info = {};
		struct dev_archdata dev_ad = {};
		const __be32 *reg;
		char tmp[16];
		u32 addr;
		int len;

		/* Get address & channel */
		reg = of_get_property(node, "reg", &len);
		if (!reg || (len < sizeof(int))) {
			dev_err(&adap->dev, "i2c-powermac: invalid reg on %s\n",
				node->full_name);
			continue;
		}
		addr = be32_to_cpup(reg);

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

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

		/* Make up a modalias. 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
		 */
		if (of_modalias_node(node, tmp, sizeof(tmp)) < 0) {
			dev_err(&adap->dev, "i2c-powermac: modalias failure"
				" on %s\n", node->full_name);
			continue;
		}
		snprintf(info.type, sizeof(info.type), "MAC,%s", tmp);

		/* Fill out the rest of the info structure */
		info.addr = (addr & 0xff) >> 1;
		info.irq = irq_of_parse_and_map(node, 0);
		info.of_node = of_node_get(node);
		info.archdata = &dev_ad;

		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;
		}
	}
}

static int __devinit i2c_powermac_probe(struct platform_device *dev)
{
	struct pmac_i2c_bus *bus = dev->dev.platform_data;
	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;
	adapter->dev.of_node = dev->dev.of_node;
	rc = i2c_add_adapter(adapter);
	if (rc) {
		printk(KERN_ERR "i2c-powermac: Adapter %s registration "
		       "failed\n", adapter->name);
		memset(adapter, 0, sizeof(*adapter));
	}

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

	/* Cannot use of_i2c_register_devices() due to Apple device-tree
	 * funkyness
	 */
	i2c_powermac_register_devices(adapter, bus);

	return rc;
}

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

module_platform_driver(i2c_powermac_driver);

MODULE_ALIAS("platform:i2c-powermac");