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/*

    i2c Support for Apple Keywest I2C Bus Controller

    Copyright (c) 2001 Benjamin Herrenschmidt <benh@kernel.crashing.org>

    Original work by

    Copyright (c) 2000 Philip Edelbrock <phil@stimpy.netroedge.com>

    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.

    Changes:

    2001/12/13 BenH     New implementation

    2001/12/15 BenH     Add support for "byte" and "quick"

                        transfers. Add i2c_xfer routine.

    My understanding of the various modes supported by keywest are:

     - Dumb mode : not implemented, probably direct tweaking of lines

     - Standard mode : simple i2c transaction of type

         S Addr R/W A Data A Data ... T

     - Standard sub mode : combined 8 bit subaddr write with data read

         S Addr R/W A SubAddr A Data A Data ... T

     - Combined mode : Subaddress and Data sequences appended with no stop

         S Addr R/W A SubAddr S Addr R/W A Data A Data ... T

    Currently, this driver uses only Standard mode for i2c xfer, and

    smbus byte & quick transfers ; and uses StandardSub mode for

    other smbus transfers instead of combined as we need that for the

    sound driver to be happy

*/

#include <linux/module.h>

#include <linux/config.h>

#include <linux/kernel.h>

#include <linux/ioport.h>

#include <linux/pci.h>

#include <linux/types.h>

#include <linux/delay.h>

#include <linux/i2c.h>

#include <linux/init.h>

#include <linux/mm.h>

#include <linux/timer.h>

#include <linux/spinlock.h>

#include <linux/completion.h>

#include <asm/io.h>

#include <asm/prom.h>

#include <asm/machdep.h>

#include <asm/pmac_feature.h>

#include "i2c-keywest.h"

#define DBG(x...) do {\

        if (debug > 0) \

                printk(KERN_DEBUG "KW:" x); \

        } while(0)

MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");

MODULE_DESCRIPTION("I2C driver for Apple's Keywest");

MODULE_LICENSE("GPL");

MODULE_PARM(probe, "i");

MODULE_PARM(debug, "i");

EXPORT_NO_SYMBOLS;

int probe = 0;

int debug = 0;

static struct keywest_iface *ifaces = NULL;

static void

do_stop(struct keywest_iface* iface, int result)

{

        write_reg(reg_control, read_reg(reg_control) | KW_I2C_CTL_STOP);

        iface->state = state_stop;

        iface->result = result;

}

/* Main state machine for standard & standard sub mode */

static int

handle_interrupt(struct keywest_iface *iface, u8 isr)

{

        int ack;

        int rearm_timer = 1;

        DBG("handle_interrupt(), got: %x, status: %x, state: %d\n",

                isr, read_reg(reg_status), iface->state);

        if (isr == 0 && iface->state != state_stop) {

                do_stop(iface, -1);

                return rearm_timer;

        }

        if (isr & KW_I2C_IRQ_STOP && iface->state != state_stop) {

                iface->result = -1;

                iface->state = state_stop;

        }

        switch(iface->state) {

        case state_addr:

                if (!(isr & KW_I2C_IRQ_ADDR)) {

                        do_stop(iface, -1);

                        break;

                }

                ack = read_reg(reg_status);

                DBG("ack on set address: %x\n", ack);

                if ((ack & KW_I2C_STAT_LAST_AAK) == 0) {

                        do_stop(iface, -1);

                        break;

                }

                /* Handle rw "quick" mode */

                if (iface->datalen == 0)

                        do_stop(iface, 0);

                else if (iface->read_write == I2C_SMBUS_READ) {

                        iface->state = state_read;

                        if (iface->datalen > 1)

                                write_reg(reg_control, read_reg(reg_control)

                                        | KW_I2C_CTL_AAK);

                } else {

                        iface->state = state_write;

                        DBG("write byte: %x\n", *(iface->data));

                        write_reg(reg_data, *(iface->data++));

                        iface->datalen--;

                }

                break;

        case state_read:

                if (!(isr & KW_I2C_IRQ_DATA)) {

                        do_stop(iface, -1);

                        break;

                }

                *(iface->data++) = read_reg(reg_data);

                DBG("read byte: %x\n", *(iface->data-1));

                iface->datalen--;

                if (iface->datalen == 0)

                        iface->state = state_stop;

                else

                        write_reg(reg_control, 0);

                break;

        case state_write:

                if (!(isr & KW_I2C_IRQ_DATA)) {

                        do_stop(iface, -1);

                        break;

                }

                /* Check ack status */

                ack = read_reg(reg_status);

                DBG("ack on data write: %x\n", ack);

                if ((ack & KW_I2C_STAT_LAST_AAK) == 0) {

                        do_stop(iface, -1);

                        break;

                }

                if (iface->datalen) {

                        DBG("write byte: %x\n", *(iface->data));

                        write_reg(reg_data, *(iface->data++));

                        iface->datalen--;

                } else

                        do_stop(iface, 0);

                break;

        case state_stop:

                if (!(isr & KW_I2C_IRQ_STOP) && (++iface->stopretry) < 10)

                        do_stop(iface, -1);

                else {

                        rearm_timer = 0;

                        iface->state = state_idle;

                        write_reg(reg_control, 0x00);

                        write_reg(reg_ier, 0x00);

                        complete(&iface->complete);

                }

                break;

        }

        write_reg(reg_isr, isr);

        return rearm_timer;

}

/* Interrupt handler */

static void

keywest_irq(int irq, void *dev_id, struct pt_regs *regs)

{

        struct keywest_iface *iface = (struct keywest_iface *)dev_id;

        spin_lock(&iface->lock);

        del_timer(&iface->timeout_timer);

        if (handle_interrupt(iface, read_reg(reg_isr))) {

                iface->timeout_timer.expires = jiffies + POLL_TIMEOUT;

                add_timer(&iface->timeout_timer);

        }

        spin_unlock(&iface->lock);

}

static void

keywest_timeout(unsigned long data)

{

        struct keywest_iface *iface = (struct keywest_iface *)data;

        DBG("timeout !\n");

        spin_lock_irq(&iface->lock);

        if (handle_interrupt(iface, read_reg(reg_isr))) {

                iface->timeout_timer.expires = jiffies + POLL_TIMEOUT;

                add_timer(&iface->timeout_timer);

        }

        spin_unlock(&iface->lock);

}

/*

 * SMBUS-type transfer entrypoint

 */

static s32

keywest_smbus_xfer(     struct i2c_adapter*     adap,

                        u16                     addr,

                        unsigned short          flags,

                        char                    read_write,

                        u8                      command,

                        int                     size,

                        union i2c_smbus_data*   data)

{

        struct keywest_chan* chan = (struct keywest_chan*)adap->data;

        struct keywest_iface* iface = chan->iface;

        int len;

        u8* buffer;

        u16 cur_word;

        int rc = 0;

        if (iface->state == state_dead)

                return -1;

        /* Prepare datas & select mode */

        iface->cur_mode &= ~KW_I2C_MODE_MODE_MASK;

        switch (size) {

            case I2C_SMBUS_QUICK:

                len = 0;

                buffer = NULL;

                iface->cur_mode |= KW_I2C_MODE_STANDARD;

                break;

            case I2C_SMBUS_BYTE:

                len = 1;

                buffer = &data->byte;

                iface->cur_mode |= KW_I2C_MODE_STANDARD;

                break;

            case I2C_SMBUS_BYTE_DATA:

                len = 1;

                buffer = &data->byte;

                iface->cur_mode |= KW_I2C_MODE_STANDARDSUB;

                break;

            case I2C_SMBUS_WORD_DATA:

                len = 2;

                cur_word = cpu_to_le16(data->word);

                buffer = (u8 *)&cur_word;

                iface->cur_mode |= KW_I2C_MODE_STANDARDSUB;

                break;

            case I2C_SMBUS_BLOCK_DATA:

                len = data->block[0];

                buffer = &data->block[1];

                iface->cur_mode |= KW_I2C_MODE_STANDARDSUB;

                break;

            default:

                return -1;

        }

        /* Original driver had this limitation */

        if (len > 32)

                len = 32;

        down(&iface->sem);

        DBG("chan: %d, addr: 0x%x, transfer len: %d, read: %d\n",

                chan->chan_no, addr, len, read_write == I2C_SMBUS_READ);

        iface->data = buffer;

        iface->datalen = len;

        iface->state = state_addr;

        iface->result = 0;

        iface->stopretry = 0;

        iface->read_write = read_write;

        /* Setup channel & clear pending irqs */

        write_reg(reg_mode, iface->cur_mode | (chan->chan_no << 4));

        write_reg(reg_isr, read_reg(reg_isr));

        write_reg(reg_status, 0);

        /* Set up address and r/w bit */

        write_reg(reg_addr,

                (addr << 1) | ((read_write == I2C_SMBUS_READ) ? 0x01 : 0x00));

        /* Set up the sub address */

        if ((iface->cur_mode & KW_I2C_MODE_MODE_MASK) == KW_I2C_MODE_STANDARDSUB

            || (iface->cur_mode & KW_I2C_MODE_MODE_MASK) == KW_I2C_MODE_COMBINED)

                write_reg(reg_subaddr, command);

        /* Arm timeout */

        iface->timeout_timer.expires = jiffies + POLL_TIMEOUT;

        add_timer(&iface->timeout_timer);

        /* Start sending address & enable interrupt*/

        write_reg(reg_control, read_reg(reg_control) | KW_I2C_CTL_XADDR);

        write_reg(reg_ier, KW_I2C_IRQ_MASK);

        wait_for_completion(&iface->complete);

        rc = iface->result;

        DBG("transfer done, result: %d\n", rc);

        if (rc == 0 && size == I2C_SMBUS_WORD_DATA && read_write == I2C_SMBUS_READ)

                data->word = le16_to_cpu(cur_word);

        /* Release sem */

        up(&iface->sem);

        return rc;

}

/*

 * Generic i2c master transfer entrypoint

 */

static int

keywest_xfer(   struct i2c_adapter *adap,

                struct i2c_msg msgs[],

                int num)

{

        struct keywest_chan* chan = (struct keywest_chan*)adap->data;

        struct keywest_iface* iface = chan->iface;

        struct i2c_msg *pmsg;

        int i, completed;

        int rc = 0;

        down(&iface->sem);

        /* Set adapter to standard mode */

        iface->cur_mode &= ~KW_I2C_MODE_MODE_MASK;

        iface->cur_mode |= KW_I2C_MODE_STANDARD;

        completed = 0;

        for (i = 0; rc >= 0 && i < num;) {

                u8 addr;

                pmsg = &msgs[i++];

                addr = pmsg->addr;

                if (pmsg->flags & I2C_M_TEN) {

                        printk(KERN_ERR "i2c-keywest: 10 bits addr not supported !\n");

                        rc = -EINVAL;

                        break;

                }

                DBG("xfer: chan: %d, doing %s %d bytes to 0x%02x - %d of %d messages\n",

                     chan->chan_no,

                     pmsg->flags & I2C_M_RD ? "read" : "write",

                     pmsg->len, addr, i, num);

                /* Setup channel & clear pending irqs */

                write_reg(reg_mode, iface->cur_mode | (chan->chan_no << 4));

                write_reg(reg_isr, read_reg(reg_isr));

                write_reg(reg_status, 0);

                iface->data = pmsg->buf;

                iface->datalen = pmsg->len;

                iface->state = state_addr;

                iface->result = 0;

                iface->stopretry = 0;

                if (pmsg->flags & I2C_M_RD)

                        iface->read_write = I2C_SMBUS_READ;

                else

                        iface->read_write = I2C_SMBUS_WRITE;

                /* Set up address and r/w bit */

                if (pmsg->flags & I2C_M_REV_DIR_ADDR)

                        addr ^= 1;

                write_reg(reg_addr,

                        (addr << 1) |

                        ((iface->read_write == I2C_SMBUS_READ) ? 0x01 : 0x00));

                /* Arm timeout */

                iface->timeout_timer.expires = jiffies + POLL_TIMEOUT;

                add_timer(&iface->timeout_timer);

                /* Start sending address & enable interrupt*/

                write_reg(reg_control, read_reg(reg_control) | KW_I2C_CTL_XADDR);

                write_reg(reg_ier, KW_I2C_IRQ_MASK);

                wait_for_completion(&iface->complete);

                rc = iface->result;

                if (rc == 0)

                        completed++;

                DBG("transfer done, result: %d\n", rc);

        }

        /* Release sem */

        up(&iface->sem);

        return completed;

}

static u32

keywest_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;

}

static void

keywest_inc(struct i2c_adapter *adapter)

{

        MOD_INC_USE_COUNT;

}

static void

keywest_dec(struct i2c_adapter *adapter)

{

        MOD_DEC_USE_COUNT;

}

/* For now, we only handle combined mode (smbus) */

static struct i2c_algorithm keywest_algorithm = {

        name:           "Keywest i2c",

        id:             I2C_ALGO_SMBUS,

        smbus_xfer:     keywest_smbus_xfer,

        master_xfer:    keywest_xfer,

        functionality:  keywest_func,

};

static int

create_iface(struct device_node* np)

{

        unsigned long steps, *psteps, *prate;

        unsigned bsteps, tsize, i, nchan, addroffset;

        struct keywest_iface* iface;

        int rc;

        psteps = (unsigned long *)get_property(np, "AAPL,address-step", NULL);

        steps = psteps ? (*psteps) : 0x10;

        /* Hrm... maybe we can be smarter here */

        for (bsteps = 0; (steps & 0x01) == 0; bsteps++)

                steps >>= 1;

        if (!strcmp(np->parent->name, "uni-n")) {

                nchan = 2;

                addroffset = 3;

        } else {

                addroffset = 0;

                nchan = 1;

        }

        tsize = sizeof(struct keywest_iface) +

                (sizeof(struct keywest_chan) + 4) * nchan;

        iface = (struct keywest_iface *) kmalloc(tsize, GFP_KERNEL);

        if (iface == NULL) {

                printk(KERN_ERR "i2c-keywest: can't allocate inteface !\n");

                return -ENOMEM;

        }

        memset(iface, 0, tsize);

        init_MUTEX(&iface->sem);

        spin_lock_init(&iface->lock);

        init_completion(&iface->complete);

        iface->bsteps = bsteps;

        iface->chan_count = nchan;

        iface->state = state_idle;

        iface->irq = np->intrs[0].line;

        iface->channels = (struct keywest_chan *)

                (((unsigned long)(iface + 1) + 3UL) & ~3UL);

        iface->base = (unsigned long)ioremap(np->addrs[0].address + addroffset,

                                                np->addrs[0].size);

        if (iface->base == 0) {

                printk(KERN_ERR "i2c-keywest: can't map inteface !\n");

                kfree(iface);

                return -ENOMEM;

        }

        init_timer(&iface->timeout_timer);

        iface->timeout_timer.function = keywest_timeout;

        iface->timeout_timer.data = (unsigned long)iface;

        /* Select interface rate */

        iface->cur_mode = KW_I2C_MODE_100KHZ;

        prate = (unsigned long *)get_property(np, "AAPL,i2c-rate", NULL);

        if (prate) switch(*prate) {

        case 100:

                iface->cur_mode = KW_I2C_MODE_100KHZ;

                break;

        case 50:

                iface->cur_mode = KW_I2C_MODE_50KHZ;

                break;

        case 25:

                iface->cur_mode = KW_I2C_MODE_25KHZ;

                break;

        default:

                printk(KERN_WARNING "i2c-keywest: unknown rate %ldKhz, using 100KHz\n",

                        *prate);

        }

        /* Select standard mode by default */

        iface->cur_mode |= KW_I2C_MODE_STANDARD;

        /* Write mode */

        write_reg(reg_mode, iface->cur_mode);

        /* Switch interrupts off & clear them*/

        write_reg(reg_ier, 0x00);

        write_reg(reg_isr, KW_I2C_IRQ_MASK);

        /* Request chip interrupt */

        rc = request_irq(iface->irq, keywest_irq, 0, "keywest i2c", iface);

        if (rc) {

                printk(KERN_ERR "i2c-keywest: can't get IRQ %d !\n", iface->irq);

                iounmap((void *)iface->base);

                kfree(iface);

                return -ENODEV;

        }

        for (i=0; i<nchan; i++) {

                struct keywest_chan* chan = &iface->channels[i];

                u8 addr;

                sprintf(chan->adapter.name, "%s %d", np->parent->name, i);

                chan->iface = iface;

                chan->chan_no = i;

                chan->adapter.id = I2C_ALGO_SMBUS;

                chan->adapter.algo = &keywest_algorithm;

                chan->adapter.algo_data = NULL;

                chan->adapter.inc_use = keywest_inc;

                chan->adapter.dec_use = keywest_dec;

                chan->adapter.client_register = NULL;

                chan->adapter.client_unregister = NULL;

                chan->adapter.data = chan;

                rc = i2c_add_adapter(&chan->adapter);

                if (rc) {

                        printk("i2c-keywest.c: Adapter %s registration failed\n",

                                chan->adapter.name);

                        chan->adapter.data = NULL;

                }

                if (probe) {

                        printk("Probe: ");

                        for (addr = 0x00; addr <= 0x7f; addr++) {

                                if (i2c_smbus_xfer(&chan->adapter,addr,

                                    0,0,0,I2C_SMBUS_QUICK,NULL) >= 0)

                                        printk("%02x ", addr);

                        }

                        printk("\n");

                }

        }

        printk(KERN_INFO "Found KeyWest i2c on \"%s\", %d channel%s, stepping: %d bits\n",

                np->parent->name, nchan, nchan > 1 ? "s" : "", bsteps);

        iface->next = ifaces;

        ifaces = iface;

        return 0;

}

static void

dispose_iface(struct keywest_iface *iface)

{

        int i, rc;

        ifaces = iface->next;

        /* Make sure we stop all activity */

        down(&iface->sem);

        spin_lock_irq(&iface->lock);

        while (iface->state != state_idle) {

                spin_unlock_irq(&iface->lock);

                set_task_state(current,TASK_UNINTERRUPTIBLE);

                schedule_timeout(HZ/10);

                spin_lock_irq(&iface->lock);

        }

        iface->state = state_dead;

        spin_unlock_irq(&iface->lock);

        free_irq(iface->irq, iface);

        up(&iface->sem);

        /* Release all channels */

        for (i=0; i<iface->chan_count; i++) {

                struct keywest_chan* chan = &iface->channels[i];

                if (!chan->adapter.data)

                        continue;

                rc = i2c_del_adapter(&chan->adapter);

                chan->adapter.data = NULL;

                /* We aren't that prepared to deal with this... */

                if (rc)

                        printk("i2c-keywest.c: i2c_del_adapter failed, that's bad !\n");

        }

        iounmap((void *)iface->base);

        kfree(iface);

}

static int __init

i2c_keywest_init(void)

{

        struct device_node *np;

        int rc = -ENODEV;

        np = find_compatible_devices("i2c", "keywest");

        while (np != 0) {

                if (np->n_addrs >= 1 && np->n_intrs >= 1)

                        rc = create_iface(np);

                np = np->next;

        }

        if (ifaces)

                rc = 0;

        return rc;

}

static void __exit

i2c_keywest_cleanup(void)

{

        while(ifaces)

                dispose_iface(ifaces);

}

module_init(i2c_keywest_init);

module_exit(i2c_keywest_cleanup);