/*
    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 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;
        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);

        if (!strncmp(basename, "uni-n", 5)) {
                struct device_node *np;
                const u32 *prop;
                struct i2c_board_info info;

                /* Instantiate I2C motion sensor if present */
                np = of_find_node_by_name(NULL, "accelerometer");
                if (np && of_device_is_compatible(np, "AAPL,accelerometer_1") &&
                    (prop = of_get_property(np, "reg", NULL))) {
                        int i2c_bus;
                        const char *tmp_bus;

                        /* look for bus either using "reg" or by path */
                        tmp_bus = strstr(np->full_name, "/i2c-bus@");
                        if (tmp_bus)
                                i2c_bus = *(tmp_bus + 9) - '0';
                        else
                                i2c_bus = ((*prop) >> 8) & 0x0f;

                        if (pmac_i2c_get_channel(bus) == i2c_bus) {
                                memset(&info, 0, sizeof(struct i2c_board_info));
                                info.addr = ((*prop) & 0xff) >> 1;
                                strlcpy(info.type, "ams", I2C_NAME_SIZE);
                                i2c_new_device(adapter, &info);
                        }
                }
        }

        return rc;
}


/* work with hotplug and coldplug */
MODULE_ALIAS("platform:i2c-powermac");

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,
        },
};

static int __init i2c_powermac_init(void)
{
        platform_driver_register(&i2c_powermac_driver);
        return 0;
}


static void __exit i2c_powermac_cleanup(void)
{
        platform_driver_unregister(&i2c_powermac_driver);
}

module_init(i2c_powermac_init);
module_exit(i2c_powermac_cleanup);