scx200_acb.c

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/*
    Copyright (c) 2001,2002 Christer Weinigel <[email protected]>

    National Semiconductor SCx200 ACCESS.bus support
    Also supports the AMD CS5535 and AMD CS5536

    Based on i2c-keywest.c which is:
        Copyright (c) 2001 Benjamin Herrenschmidt <[email protected]>
        Copyright (c) 2000 Philip Edelbrock <[email protected]>

    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.
*/

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/pci.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/io.h>

#include <linux/scx200.h>

MODULE_AUTHOR("Christer Weinigel <[email protected]>");
MODULE_DESCRIPTION("NatSemi SCx200 ACCESS.bus Driver");
MODULE_ALIAS("platform:cs5535-smb");
MODULE_LICENSE("GPL");

#define MAX_DEVICES 4
static int base[MAX_DEVICES] = { 0x820, 0x840 };
module_param_array(base, int, NULL, 0);
MODULE_PARM_DESC(base, "Base addresses for the ACCESS.bus controllers");

#define POLL_TIMEOUT    (HZ/5)

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 mutex mutex;

    /* 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;

    dev_dbg(&iface->adapter.dev, "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) {
        dev_dbg(&iface->adapter.dev, "negative ack 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);

        /* Reset the status register */
        outb(0, ACBST);
        return;
    }

    switch (iface->state) {
    case state_idle:
        dev_warn(&iface->adapter.dev, "interrupt in idle state\n");
        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 _next_ byte will be the last one */
        if (iface->len == 2)
            outb(inb(ACBCTL1) | ACBCTL1_ACK, ACBCTL1);
        else
            outb(inb(ACBCTL1) & ~ACBCTL1_ACK, ACBCTL1);

        if (iface->len == 1) {
            iface->result = 0;
            iface->state = state_idle;
            outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
        }

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

        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;

 error:
    dev_err(&iface->adapter.dev,
        "%s in state %s (addr=0x%02x, len=%d, status=0x%02x)\n", errmsg,
        scx200_acb_state_name[iface->state], iface->address_byte,
        iface->len, status);

    iface->state = state_idle;
    iface->result = -EIO;
    iface->needs_reset = 1;
}

static void scx200_acb_poll(struct scx200_acb_iface *iface)
{
    u8 status;
    unsigned long timeout;

    timeout = jiffies + POLL_TIMEOUT;
    while (1) {
        status = inb(ACBST);

        /* Reset the status register to avoid the hang */
        outb(0, ACBST);

        if ((status & (ACBST_SDAST|ACBST_BER|ACBST_NEGACK)) != 0) {
            scx200_acb_machine(iface, status);
            return;
        }
        if (time_after(jiffies, timeout))
            break;
        cpu_relax();
        cond_resched();
    }

    dev_err(&iface->adapter.dev, "timeout in state %s\n",
        scx200_acb_state_name[iface->state]);

    iface->state = state_idle;
    iface->result = -EIO;
    iface->needs_reset = 1;
}

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 = i2c_get_adapdata(adapter);
    int len;
    u8 *buffer;
    u16 cur_word;
    int rc;

    switch (size) {
    case I2C_SMBUS_QUICK:
        len = 0;
        buffer = NULL;
        break;

    case I2C_SMBUS_BYTE:
        len = 1;
        buffer = rw ? &data->byte : &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_I2C_BLOCK_DATA:
        len = data->block[0];
        if (len == 0 || len > I2C_SMBUS_BLOCK_MAX)
            return -EINVAL;
        buffer = &data->block[1];
        break;

    default:
        return -EINVAL;
    }

    dev_dbg(&adapter->dev,
        "size=%d, address=0x%x, command=0x%x, len=%d, read=%d\n",
        size, address, command, len, rw);

    if (!len && rw == I2C_SMBUS_READ) {
        dev_dbg(&adapter->dev, "zero length read\n");
        return -EINVAL;
    }

    mutex_lock(&iface->mutex);

    iface->address_byte = (address << 1) | rw;
    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;

    while (iface->state != state_idle)
        scx200_acb_poll(iface);

    if (iface->needs_reset)
        scx200_acb_reset(iface);

    rc = iface->result;

    mutex_unlock(&iface->mutex);

    if (rc == 0 && size == I2C_SMBUS_WORD_DATA && rw == I2C_SMBUS_READ)
        data->word = le16_to_cpu(cur_word);

#ifdef DEBUG
    dev_dbg(&adapter->dev, "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_I2C_BLOCK;
}

/* For now, we only handle combined mode (smbus) */
static const struct i2c_algorithm scx200_acb_algorithm = {
    .smbus_xfer = scx200_acb_smbus_xfer,
    .functionality  = scx200_acb_func,
};

static struct scx200_acb_iface *scx200_acb_list;
static DEFINE_MUTEX(scx200_acb_list_mutex);

static __devinit 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) {
        pr_debug("ACBCTL2 readback failed\n");
        return -ENXIO;
    }

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

    val = inb(ACBCTL1);
    if (val) {
        pr_debug("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) {
        pr_debug("enabled, but NMINTE won't be set, ACBCTL1=0x%02x\n",
             val);
        return -ENXIO;
    }

    return 0;
}

static __devinit struct scx200_acb_iface *scx200_create_iface(const char *text,
        struct device *dev, int index)
{
    struct scx200_acb_iface *iface;
    struct i2c_adapter *adapter;

    iface = kzalloc(sizeof(*iface), GFP_KERNEL);
    if (!iface) {
        pr_err("can't allocate memory\n");
        return NULL;
    }

    adapter = &iface->adapter;
    i2c_set_adapdata(adapter, iface);
    snprintf(adapter->name, sizeof(adapter->name), "%s ACB%d", text, index);
    adapter->owner = THIS_MODULE;
    adapter->algo = &scx200_acb_algorithm;
    adapter->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
    adapter->dev.parent = dev;

    mutex_init(&iface->mutex);

    return iface;
}

static int __devinit scx200_acb_create(struct scx200_acb_iface *iface)
{
    struct i2c_adapter *adapter;
    int rc;

    adapter = &iface->adapter;

    rc = scx200_acb_probe(iface);
    if (rc) {
        pr_warn("probe failed\n");
        return rc;
    }

    scx200_acb_reset(iface);

    if (i2c_add_adapter(adapter) < 0) {
        pr_err("failed to register\n");
        return -ENODEV;
    }

    if (!adapter->dev.parent) {
        /* If there's no dev, we're tracking (ISA) ifaces manually */
        mutex_lock(&scx200_acb_list_mutex);
        iface->next = scx200_acb_list;
        scx200_acb_list = iface;
        mutex_unlock(&scx200_acb_list_mutex);
    }

    return 0;
}

static struct scx200_acb_iface * __devinit scx200_create_dev(const char *text,
        unsigned long base, int index, struct device *dev)
{
    struct scx200_acb_iface *iface;
    int rc;

    iface = scx200_create_iface(text, dev, index);

    if (iface == NULL)
        return NULL;

    if (!request_region(base, 8, iface->adapter.name)) {
        pr_err("can't allocate io 0x%lx-0x%lx\n", base, base + 8 - 1);
        goto errout_free;
    }

    iface->base = base;
    rc = scx200_acb_create(iface);

    if (rc == 0)
        return iface;

    release_region(base, 8);
 errout_free:
    kfree(iface);
    return NULL;
}

static int __devinit scx200_probe(struct platform_device *pdev)
{
    struct scx200_acb_iface *iface;
    struct resource *res;

    res = platform_get_resource(pdev, IORESOURCE_IO, 0);
    if (!res) {
        dev_err(&pdev->dev, "can't fetch device resource info\n");
        return -ENODEV;
    }

    iface = scx200_create_dev("CS5535", res->start, 0, &pdev->dev);
    if (!iface)
        return -EIO;

    dev_info(&pdev->dev, "SCx200 device '%s' registered\n",
            iface->adapter.name);
    platform_set_drvdata(pdev, iface);

    return 0;
}

static void __devexit scx200_cleanup_iface(struct scx200_acb_iface *iface)
{
    i2c_del_adapter(&iface->adapter);
    release_region(iface->base, 8);
    kfree(iface);
}

static int __devexit scx200_remove(struct platform_device *pdev)
{
    struct scx200_acb_iface *iface;

    iface = platform_get_drvdata(pdev);
    platform_set_drvdata(pdev, NULL);
    scx200_cleanup_iface(iface);

    return 0;
}

static struct platform_driver scx200_pci_driver = {
    .driver = {
        .name = "cs5535-smb",
        .owner = THIS_MODULE,
    },
    .probe = scx200_probe,
    .remove = __devexit_p(scx200_remove),
};

static DEFINE_PCI_DEVICE_TABLE(scx200_isa) = {
    { PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_SCx200_BRIDGE) },
    { PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_SC1100_BRIDGE) },
    { 0, }
};

static __init void scx200_scan_isa(void)
{
    int i;

    if (!pci_dev_present(scx200_isa))
        return;

    for (i = 0; i < MAX_DEVICES; ++i) {
        if (base[i] == 0)
            continue;

        /* XXX: should we care about failures? */
        scx200_create_dev("SCx200", base[i], i, NULL);
    }
}

static int __init scx200_acb_init(void)
{
    pr_debug("NatSemi SCx200 ACCESS.bus Driver\n");

    /* First scan for ISA-based devices */
    scx200_scan_isa();  /* XXX: should we care about errors? */

    /* If at least one bus was created, init must succeed */
    if (scx200_acb_list)
        return 0;

    /* No ISA devices; register the platform driver for PCI-based devices */
    return platform_driver_register(&scx200_pci_driver);
}

static void __exit scx200_acb_cleanup(void)
{
    struct scx200_acb_iface *iface;

    platform_driver_unregister(&scx200_pci_driver);

    mutex_lock(&scx200_acb_list_mutex);
    while ((iface = scx200_acb_list) != NULL) {
        scx200_acb_list = iface->next;
        mutex_unlock(&scx200_acb_list_mutex);

        scx200_cleanup_iface(iface);

        mutex_lock(&scx200_acb_list_mutex);
    }
    mutex_unlock(&scx200_acb_list_mutex);
}

module_init(scx200_acb_init);
module_exit(scx200_acb_cleanup);