/*
    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.

*/

#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 <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                     addrdir;

        if (msgs->flags & I2C_M_TEN)
                return -EINVAL;
        addrdir = i2c_8bit_addr_from_msg(msgs);

        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 const struct i2c_adapter_quirks i2c_powermac_quirks = {
        .max_num_msgs = 1,
};

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 %pOF\n", node);

        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 %pOF\n", node);
        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 %pOF\n", node);

                /*
                 * 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"
                                " %pOF\n", node);
                        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;
        adapter->quirks = &i2c_powermac_quirks;
        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");