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/*  linux/drivers/i2c/scx200_acb.c

    Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>

    National Semiconductor SCx200 ACCESS.bus support

    Based on i2c-keywest.c which is:

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

        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.

*/

#include <linux/config.h>

#include <linux/module.h>

#include <linux/errno.h>

#include <linux/kernel.h>

#include <linux/sched.h>

#include <linux/init.h>

#include <linux/i2c.h>

#include <linux/smp_lock.h>

#include <linux/pci.h>

#include <asm/io.h>

#include <linux/scx200.h>

#define NAME "scx200_acb"

MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");

MODULE_DESCRIPTION("NatSemi SCx200 ACCESS.bus Driver");

MODULE_LICENSE("GPL");

#define MAX_DEVICES 4

static int base[MAX_DEVICES] = { 0x840 };

MODULE_PARM(base, "1-4i");

MODULE_PARM_DESC(base, "Base addresses for the ACCESS.bus controllers");

#define DEBUG 0

#if DEBUG

#define DBG(x...) printk(KERN_DEBUG NAME ": " x)

#else

#define DBG(x...)

#endif

/* The hardware supports interrupt driven mode too, but I haven't

   implemented that. */

#define POLLED_MODE 1

#define POLL_TIMEOUT (HZ)

enum scx200_acb_state {

        state_idle,

        state_address,

        state_command,

        state_repeat_start,

        state_quick,

        state_read,

        state_write,

};

static const char *scx200_acb_state_name[] = {

        "idle",

        "address",

        "command",

        "repeat_start",

        "quick",

        "read",

        "write",

};

/* Physical interface */

struct scx200_acb_iface

{

        struct scx200_acb_iface *next;

        struct i2c_adapter adapter;

        unsigned base;

        struct semaphore sem;

        /* State machine data */

        enum scx200_acb_state state;

        int result;

        u8 address_byte;

        u8 command;

        u8 *ptr;

        char needs_reset;

        unsigned len;

};

/* Register Definitions */

#define ACBSDA          (iface->base + 0)

#define ACBST           (iface->base + 1)

#define    ACBST_SDAST          0x40 /* SDA Status */

#define    ACBST_BER            0x20 

#define    ACBST_NEGACK         0x10 /* Negative Acknowledge */

#define    ACBST_STASTR         0x08 /* Stall After Start */

#define    ACBST_MASTER         0x02

#define ACBCST          (iface->base + 2)

#define    ACBCST_BB            0x02

#define ACBCTL1         (iface->base + 3)

#define    ACBCTL1_STASTRE      0x80

#define    ACBCTL1_NMINTE       0x40

#define    ACBCTL1_ACK          0x10

#define    ACBCTL1_STOP         0x02

#define    ACBCTL1_START        0x01

#define ACBADDR         (iface->base + 4)

#define ACBCTL2         (iface->base + 5)

#define    ACBCTL2_ENABLE       0x01

/************************************************************************/

static void scx200_acb_machine(struct scx200_acb_iface *iface, u8 status)

{

        const char *errmsg;

        DBG("state %s, status = 0x%02x\n",

            scx200_acb_state_name[iface->state], status);

        if (status & ACBST_BER) {

                errmsg = "bus error";

                goto error;

        }

        if (!(status & ACBST_MASTER)) {

                errmsg = "not master";

                goto error;

        }

        if (status & ACBST_NEGACK)

                goto negack;

        switch (iface->state) {

        case state_idle:

                printk(KERN_WARNING NAME ": %s, interrupt in idle state\n",

                       iface->adapter.name);

                break;

        case state_address:

                /* Do a pointer write first */

                outb(iface->address_byte & ~1, ACBSDA);

                iface->state = state_command;

                break;

        case state_command:

                outb(iface->command, ACBSDA);

                if (iface->address_byte & 1)

                        iface->state = state_repeat_start;

                else

                        iface->state = state_write;

                break;

        case state_repeat_start:

                outb(inb(ACBCTL1) | ACBCTL1_START, ACBCTL1);

                /* fallthrough */

        case state_quick:

                if (iface->address_byte & 1) {

                        if (iface->len == 1)

                                outb(inb(ACBCTL1) | ACBCTL1_ACK, ACBCTL1);

                        else

                                outb(inb(ACBCTL1) & ~ACBCTL1_ACK, ACBCTL1);

                        outb(iface->address_byte, ACBSDA);

                        iface->state = state_read;

                } else {

                        outb(iface->address_byte, ACBSDA);

                        iface->state = state_write;

                }

                break;

        case state_read:

                /* Set ACK if receiving the last byte */

                if (iface->len == 1)

                        outb(inb(ACBCTL1) | ACBCTL1_ACK, ACBCTL1);

                else

                        outb(inb(ACBCTL1) & ~ACBCTL1_ACK, ACBCTL1);

                *iface->ptr++ = inb(ACBSDA);

                --iface->len;

                if (iface->len == 0) {

                        iface->result = 0;

                        iface->state = state_idle;

                        outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);

                }

                break;

        case state_write:

                if (iface->len == 0) {

                        iface->result = 0;

                        iface->state = state_idle;

                        outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);

                        break;

                }

                outb(*iface->ptr++, ACBSDA);

                --iface->len;

                break;

        }

        return;

 negack:

        DBG("negative acknowledge in state %s\n",

            scx200_acb_state_name[iface->state]);

        iface->state = state_idle;

        iface->result = -ENXIO;

        outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);

        outb(ACBST_STASTR | ACBST_NEGACK, ACBST);

        return;

 error:

        printk(KERN_ERR NAME ": %s, %s in state %s\n", iface->adapter.name,

               errmsg, scx200_acb_state_name[iface->state]);

        iface->state = state_idle;

        iface->result = -EIO;

        iface->needs_reset = 1;

}

static void scx200_acb_timeout(struct scx200_acb_iface *iface)

{

        printk(KERN_ERR NAME ": %s, timeout in state %s\n",

               iface->adapter.name, scx200_acb_state_name[iface->state]);

        iface->state = state_idle;

        iface->result = -EIO;

        iface->needs_reset = 1;

}

#ifdef POLLED_MODE

static void scx200_acb_poll(struct scx200_acb_iface *iface)

{

        u8 status = 0;

        unsigned long timeout;

        timeout = jiffies + POLL_TIMEOUT;

        while (time_before(jiffies, timeout)) {

                status = inb(ACBST);

                if ((status & (ACBST_SDAST|ACBST_BER|ACBST_NEGACK)) != 0) {

                        scx200_acb_machine(iface, status);

                        return;

                }

                yield();

        }

        scx200_acb_timeout(iface);

}

#endif /* POLLED_MODE */

static void scx200_acb_reset(struct scx200_acb_iface *iface)

{

        /* Disable the ACCESS.bus device and Configure the SCL

           frequency: 16 clock cycles */

        outb(0x70, ACBCTL2);

        /* Polling mode */

        outb(0, ACBCTL1);

        /* Disable slave address */

        outb(0, ACBADDR);

        /* Enable the ACCESS.bus device */

        outb(inb(ACBCTL2) | ACBCTL2_ENABLE, ACBCTL2);

        /* Free STALL after START */

        outb(inb(ACBCTL1) & ~(ACBCTL1_STASTRE | ACBCTL1_NMINTE), ACBCTL1);

        /* Send a STOP */

        outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);

        /* Clear BER, NEGACK and STASTR bits */

        outb(ACBST_BER | ACBST_NEGACK | ACBST_STASTR, ACBST);

        /* Clear BB bit */

        outb(inb(ACBCST) | ACBCST_BB, ACBCST);

}

static s32 scx200_acb_smbus_xfer(struct i2c_adapter *adapter,

                                u16 address, unsigned short flags,

                                char rw, u8 command, int size,

                                union i2c_smbus_data *data)

{

        struct scx200_acb_iface *iface = adapter->data;

        int len;

        u8 *buffer;

        u16 cur_word;

        int rc;

        switch (size) {

        case I2C_SMBUS_QUICK:

                len = 0;

                buffer = NULL;

                break;

        case I2C_SMBUS_BYTE:

                if (rw == I2C_SMBUS_READ) {

                        len = 1;

                        buffer = &data->byte;

                } else {

                        len = 1;

                        buffer = &command;

                }

                break;

        case I2C_SMBUS_BYTE_DATA:

                len = 1;

                buffer = &data->byte;

                break;

        case I2C_SMBUS_WORD_DATA:

                len = 2;

                cur_word = cpu_to_le16(data->word);

                buffer = (u8 *)&cur_word;

                break;

        case I2C_SMBUS_BLOCK_DATA:

                len = data->block[0];

                buffer = &data->block[1];

                break;

        default:

                return -EINVAL;

        }

        DBG("size=%d, address=0x%x, command=0x%x, len=%d, read=%d\n",

            size, address, command, len, rw == I2C_SMBUS_READ);

        if (!len && rw == I2C_SMBUS_READ) {

                printk(KERN_WARNING NAME ": %s, zero length read\n",

                       adapter->name);

                return -EINVAL;

        }

        if (len && !buffer) {

                printk(KERN_WARNING NAME ": %s, nonzero length but no buffer\n", adapter->name);

                return -EFAULT;

        }

        down(&iface->sem);

        iface->address_byte = address<<1;

        if (rw == I2C_SMBUS_READ)

                iface->address_byte |= 1;

        iface->command = command;

        iface->ptr = buffer;

        iface->len = len;

        iface->result = -EINVAL;

        iface->needs_reset = 0;

        outb(inb(ACBCTL1) | ACBCTL1_START, ACBCTL1);

        if (size == I2C_SMBUS_QUICK || size == I2C_SMBUS_BYTE)

                iface->state = state_quick;

        else

                iface->state = state_address;

#ifdef POLLED_MODE

        while (iface->state != state_idle)

                scx200_acb_poll(iface);

#else /* POLLED_MODE */

#error Interrupt driven mode not implemented

#endif /* POLLED_MODE */        

        if (iface->needs_reset)

                scx200_acb_reset(iface);

        rc = iface->result;

        up(&iface->sem);

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

                data->word = le16_to_cpu(cur_word);

#if DEBUG

        printk(KERN_DEBUG NAME ": transfer done, result: %d", rc);

        if (buffer) {

                int i;

                printk(" data:");

                for (i = 0; i < len; ++i)

                        printk(" %02x", buffer[i]);

        }

        printk("\n");

#endif

        return rc;

}

static u32 scx200_acb_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 int scx200_acb_reg(struct i2c_client *client)

{

        return 0;

}

static int scx200_acb_unreg(struct i2c_client *client)

{

        return 0;

}

static void scx200_acb_inc_use(struct i2c_adapter *adapter)

{

        MOD_INC_USE_COUNT;

}

static void scx200_acb_dec_use(struct i2c_adapter *adapter)

{

        MOD_DEC_USE_COUNT;

}

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

static struct i2c_algorithm scx200_acb_algorithm = {

        name:           "NatSemi SCx200 ACCESS.bus",

        id:             I2C_ALGO_SMBUS,

        smbus_xfer:     scx200_acb_smbus_xfer,

        functionality:  scx200_acb_func,

};

struct scx200_acb_iface *scx200_acb_list;

int scx200_acb_probe(struct scx200_acb_iface *iface)

{

        u8 val;

        /* Disable the ACCESS.bus device and Configure the SCL

           frequency: 16 clock cycles */

        outb(0x70, ACBCTL2);

        if (inb(ACBCTL2) != 0x70) {

                DBG("ACBCTL2 readback failed\n");

                return -ENXIO;

        }

        outb(inb(ACBCTL1) | ACBCTL1_NMINTE, ACBCTL1);

        val = inb(ACBCTL1);

        if (val) {

                DBG("disabled, but ACBCTL1=0x%02x\n", val);

                return -ENXIO;

        }

        outb(inb(ACBCTL2) | ACBCTL2_ENABLE, ACBCTL2);

        outb(inb(ACBCTL1) | ACBCTL1_NMINTE, ACBCTL1);

        val = inb(ACBCTL1);

        if ((val & ACBCTL1_NMINTE) != ACBCTL1_NMINTE) {

                DBG("enabled, but NMINTE won't be set, ACBCTL1=0x%02x\n", val);

                return -ENXIO;

        }

        return 0;

}

static int  __init scx200_acb_create(int base, int index)

{

        struct scx200_acb_iface *iface;

        struct i2c_adapter *adapter;

        int rc = 0;

        char description[64];

        iface = kmalloc(sizeof(*iface), GFP_KERNEL);

        if (!iface) {

                printk(KERN_ERR NAME ": can't allocate memory\n");

                rc = -ENOMEM;

                goto errout;

        }

        memset(iface, 0, sizeof(*iface));

        adapter = &iface->adapter;

        adapter->data = iface;

        sprintf(adapter->name, "SCx200 ACB%d", index);

        adapter->id = I2C_ALGO_SMBUS;

        adapter->algo = &scx200_acb_algorithm;

        adapter->inc_use = scx200_acb_inc_use;

        adapter->dec_use = scx200_acb_dec_use;

        adapter->client_register = scx200_acb_reg;

        adapter->client_unregister = scx200_acb_unreg;

        init_MUTEX(&iface->sem);

        sprintf(description, "NatSemi SCx200 ACCESS.bus [%s]", adapter->name);

        if (request_region(base, 8, description) == 0) {

                printk(KERN_ERR NAME ": %s, can't allocate io 0x%x-0x%x\n",

                       adapter->name, base, base + 8-1);

                rc = -EBUSY;

                goto errout;

        }

        iface->base = base;

        rc = scx200_acb_probe(iface);

        if (rc) {

                printk(KERN_WARNING NAME ": %s, probe failed\n", adapter->name);

                goto errout;

        }

        scx200_acb_reset(iface);

        if (i2c_add_adapter(adapter) < 0) {

                printk(KERN_ERR NAME ": %s, failed to register\n", adapter->name);

                rc = -ENODEV;

                goto errout;

        }

        lock_kernel();

        iface->next = scx200_acb_list;

        scx200_acb_list = iface;

        unlock_kernel();

        return 0;

 errout:

        if (iface) {

                if (iface->base)

                        release_region(iface->base, 8);

                kfree(iface);

        }

        return rc;

}

static int __init scx200_acb_init(void)

{

        int i;

        int rc;

        printk(KERN_DEBUG NAME ": NatSemi SCx200 ACCESS.bus Driver\n");

        /* Verify that this really is a SCx200 processor */

        if (pci_find_device(PCI_VENDOR_ID_NS,

                            PCI_DEVICE_ID_NS_SCx200_BRIDGE,

                            NULL) == NULL)

                return -ENODEV;

        rc = -ENXIO;

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

                if (base[i] > 0)

                        rc = scx200_acb_create(base[i], i);

        }

        if (scx200_acb_list)

                return 0;

        return rc;

}

static void __exit scx200_acb_cleanup(void)

{

        struct scx200_acb_iface *iface;

        lock_kernel();

        while ((iface = scx200_acb_list) != NULL) {

                scx200_acb_list = iface->next;

                unlock_kernel();

                i2c_del_adapter(&iface->adapter);

                release_region(iface->base, 8);

                kfree(iface);

                lock_kernel();

        }

        unlock_kernel();

}

module_init(scx200_acb_init);

module_exit(scx200_acb_cleanup);

/*

    Local variables:

        compile-command: "make -k -C ../.. SUBDIRS=drivers/i2c modules"

        c-basic-offset: 8

    End:

*/