/*
    Copyright (c) 1998, 1999  Frodo Looijaard <frodol@dds.nl> and
    Philip Edelbrock <phil@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.
*/

/* Note: we assume there can only be one SIS5595 with one SMBus interface */

/*
   Note: all have mfr. ID 0x1039.
   SUPPORTED            PCI ID          
        5595            0008

   Note: these chips contain a 0008 device which is incompatible with the
         5595. We recognize these by the presence of the listed
         "blacklist" PCI ID and refuse to load.

   NOT SUPPORTED        PCI ID          BLACKLIST PCI ID        
         540            0008            0540
         550            0008            0550
        5513            0008            5511
        5581            0008            5597
        5582            0008            5597
        5597            0008            5597
        5598            0008            5597/5598
         630            0008            0630
         645            0008            0645
         646            0008            0646
         648            0008            0648
         650            0008            0650
         651            0008            0651
         730            0008            0730
         735            0008            0735
         745            0008            0745
         746            0008            0746
*/

/* TO DO: 
 * Add Block Transfers (ugly, but supported by the adapter)
 * Add adapter resets
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/pci.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/acpi.h>
#include <linux/io.h>

static int blacklist[] = {
        PCI_DEVICE_ID_SI_540,
        PCI_DEVICE_ID_SI_550,
        PCI_DEVICE_ID_SI_630,
        PCI_DEVICE_ID_SI_645,
        PCI_DEVICE_ID_SI_646,
        PCI_DEVICE_ID_SI_648,
        PCI_DEVICE_ID_SI_650,
        PCI_DEVICE_ID_SI_651,
        PCI_DEVICE_ID_SI_730,
        PCI_DEVICE_ID_SI_735,
        PCI_DEVICE_ID_SI_745,
        PCI_DEVICE_ID_SI_746,
        PCI_DEVICE_ID_SI_5511,  /* 5513 chip has the 0008 device but that ID
                                   shows up in other chips so we use the 5511
                                   ID for recognition */
        PCI_DEVICE_ID_SI_5597,
        PCI_DEVICE_ID_SI_5598,
        0,                      /* terminates the list */
};

/* Length of ISA address segment */
#define SIS5595_EXTENT          8
/* SIS5595 SMBus registers */
#define SMB_STS_LO              0x00
#define SMB_STS_HI              0x01
#define SMB_CTL_LO              0x02
#define SMB_CTL_HI              0x03
#define SMB_ADDR                0x04
#define SMB_CMD                 0x05
#define SMB_PCNT                0x06
#define SMB_CNT                 0x07
#define SMB_BYTE                0x08
#define SMB_DEV                 0x10
#define SMB_DB0                 0x11
#define SMB_DB1                 0x12
#define SMB_HAA                 0x13

/* PCI Address Constants */
#define SMB_INDEX               0x38
#define SMB_DAT                 0x39
#define SIS5595_ENABLE_REG      0x40
#define ACPI_BASE               0x90

/* Other settings */
#define MAX_TIMEOUT             500

/* SIS5595 constants */
#define SIS5595_QUICK           0x00
#define SIS5595_BYTE            0x02
#define SIS5595_BYTE_DATA       0x04
#define SIS5595_WORD_DATA       0x06
#define SIS5595_PROC_CALL       0x08
#define SIS5595_BLOCK_DATA      0x0A

/* insmod parameters */

/* If force_addr is set to anything different from 0, we forcibly enable
   the device at the given address. */
static u16 force_addr;
module_param(force_addr, ushort, 0);
MODULE_PARM_DESC(force_addr, "Initialize the base address of the i2c controller");

static struct pci_driver sis5595_driver;
static unsigned short sis5595_base;
static struct pci_dev *sis5595_pdev;

static u8 sis5595_read(u8 reg)
{
        outb(reg, sis5595_base + SMB_INDEX);
        return inb(sis5595_base + SMB_DAT);
}

static void sis5595_write(u8 reg, u8 data)
{
        outb(reg, sis5595_base + SMB_INDEX);
        outb(data, sis5595_base + SMB_DAT);
}

static int sis5595_setup(struct pci_dev *SIS5595_dev)
{
        u16 a;
        u8 val;
        int *i;
        int retval;

        /* Look for imposters */
        for (i = blacklist; *i != 0; i++) {
                struct pci_dev *dev;
                dev = pci_get_device(PCI_VENDOR_ID_SI, *i, NULL);
                if (dev) {
                        dev_err(&SIS5595_dev->dev, "Looked for SIS5595 but found unsupported device %.4x\n", *i);
                        pci_dev_put(dev);
                        return -ENODEV;
                }
        }

        /* Determine the address of the SMBus areas */
        pci_read_config_word(SIS5595_dev, ACPI_BASE, &sis5595_base);
        if (sis5595_base == 0 && force_addr == 0) {
                dev_err(&SIS5595_dev->dev, "ACPI base address uninitialized - upgrade BIOS or use force_addr=0xaddr\n");
                return -ENODEV;
        }

        if (force_addr)
                sis5595_base = force_addr & ~(SIS5595_EXTENT - 1);
        dev_dbg(&SIS5595_dev->dev, "ACPI Base address: %04x\n", sis5595_base);

        /* NB: We grab just the two SMBus registers here, but this may still
         * interfere with ACPI :-(  */
        retval = acpi_check_region(sis5595_base + SMB_INDEX, 2,
                                   sis5595_driver.name);
        if (retval)
                return retval;

        if (!request_region(sis5595_base + SMB_INDEX, 2,
                            sis5595_driver.name)) {
                dev_err(&SIS5595_dev->dev, "SMBus registers 0x%04x-0x%04x already in use!\n",
                        sis5595_base + SMB_INDEX, sis5595_base + SMB_INDEX + 1);
                return -ENODEV;
        }

        if (force_addr) {
                dev_info(&SIS5595_dev->dev, "forcing ISA address 0x%04X\n", sis5595_base);
                if (pci_write_config_word(SIS5595_dev, ACPI_BASE, sis5595_base)
                    != PCIBIOS_SUCCESSFUL)
                        goto error;
                if (pci_read_config_word(SIS5595_dev, ACPI_BASE, &a)
                    != PCIBIOS_SUCCESSFUL)
                        goto error;
                if ((a & ~(SIS5595_EXTENT - 1)) != sis5595_base) {
                        /* doesn't work for some chips! */
                        dev_err(&SIS5595_dev->dev, "force address failed - not supported?\n");
                        goto error;
                }
        }

        if (pci_read_config_byte(SIS5595_dev, SIS5595_ENABLE_REG, &val)
            != PCIBIOS_SUCCESSFUL)
                goto error;
        if ((val & 0x80) == 0) {
                dev_info(&SIS5595_dev->dev, "enabling ACPI\n");
                if (pci_write_config_byte(SIS5595_dev, SIS5595_ENABLE_REG, val | 0x80)
                    != PCIBIOS_SUCCESSFUL)
                        goto error;
                if (pci_read_config_byte(SIS5595_dev, SIS5595_ENABLE_REG, &val)
                    != PCIBIOS_SUCCESSFUL)
                        goto error;
                if ((val & 0x80) == 0) {
                        /* doesn't work for some chips? */
                        dev_err(&SIS5595_dev->dev, "ACPI enable failed - not supported?\n");
                        goto error;
                }
        }

        /* Everything is happy */
        return 0;

error:
        release_region(sis5595_base + SMB_INDEX, 2);
        return -ENODEV;
}

static int sis5595_transaction(struct i2c_adapter *adap)
{
        int temp;
        int result = 0;
        int timeout = 0;

        /* Make sure the SMBus host is ready to start transmitting */
        temp = sis5595_read(SMB_STS_LO) + (sis5595_read(SMB_STS_HI) << 8);
        if (temp != 0x00) {
                dev_dbg(&adap->dev, "SMBus busy (%04x). Resetting...\n", temp);
                sis5595_write(SMB_STS_LO, temp & 0xff);
                sis5595_write(SMB_STS_HI, temp >> 8);
                if ((temp = sis5595_read(SMB_STS_LO) + (sis5595_read(SMB_STS_HI) << 8)) != 0x00) {
                        dev_dbg(&adap->dev, "Failed! (%02x)\n", temp);
                        return -EBUSY;
                } else {
                        dev_dbg(&adap->dev, "Successful!\n");
                }
        }

        /* start the transaction by setting bit 4 */
        sis5595_write(SMB_CTL_LO, sis5595_read(SMB_CTL_LO) | 0x10);

        /* We will always wait for a fraction of a second! */
        do {
                msleep(1);
                temp = sis5595_read(SMB_STS_LO);
        } while (!(temp & 0x40) && (timeout++ < MAX_TIMEOUT));

        /* If the SMBus is still busy, we give up */
        if (timeout > MAX_TIMEOUT) {
                dev_dbg(&adap->dev, "SMBus Timeout!\n");
                result = -ETIMEDOUT;
        }

        if (temp & 0x10) {
                dev_dbg(&adap->dev, "Error: Failed bus transaction\n");
                result = -ENXIO;
        }

        if (temp & 0x20) {
                dev_err(&adap->dev, "Bus collision! SMBus may be locked until "
                        "next hard reset (or not...)\n");
                /* Clock stops and slave is stuck in mid-transmission */
                result = -EIO;
        }

        temp = sis5595_read(SMB_STS_LO) + (sis5595_read(SMB_STS_HI) << 8);
        if (temp != 0x00) {
                sis5595_write(SMB_STS_LO, temp & 0xff);
                sis5595_write(SMB_STS_HI, temp >> 8);
        }

        temp = sis5595_read(SMB_STS_LO) + (sis5595_read(SMB_STS_HI) << 8);
        if (temp != 0x00)
                dev_dbg(&adap->dev, "Failed reset at end of transaction (%02x)\n", temp);

        return result;
}

/* Return negative errno on error. */
static s32 sis5595_access(struct i2c_adapter *adap, u16 addr,
                          unsigned short flags, char read_write,
                          u8 command, int size, union i2c_smbus_data *data)
{
        int status;

        switch (size) {
        case I2C_SMBUS_QUICK:
                sis5595_write(SMB_ADDR, ((addr & 0x7f) << 1) | (read_write & 0x01));
                size = SIS5595_QUICK;
                break;
        case I2C_SMBUS_BYTE:
                sis5595_write(SMB_ADDR, ((addr & 0x7f) << 1) | (read_write & 0x01));
                if (read_write == I2C_SMBUS_WRITE)
                        sis5595_write(SMB_CMD, command);
                size = SIS5595_BYTE;
                break;
        case I2C_SMBUS_BYTE_DATA:
                sis5595_write(SMB_ADDR, ((addr & 0x7f) << 1) | (read_write & 0x01));
                sis5595_write(SMB_CMD, command);
                if (read_write == I2C_SMBUS_WRITE)
                        sis5595_write(SMB_BYTE, data->byte);
                size = SIS5595_BYTE_DATA;
                break;
        case I2C_SMBUS_PROC_CALL:
        case I2C_SMBUS_WORD_DATA:
                sis5595_write(SMB_ADDR, ((addr & 0x7f) << 1) | (read_write & 0x01));
                sis5595_write(SMB_CMD, command);
                if (read_write == I2C_SMBUS_WRITE) {
                        sis5595_write(SMB_BYTE, data->word & 0xff);
                        sis5595_write(SMB_BYTE + 1,
                                      (data->word & 0xff00) >> 8);
                }
                size = (size == I2C_SMBUS_PROC_CALL) ? SIS5595_PROC_CALL : SIS5595_WORD_DATA;
                break;
        default:
                dev_warn(&adap->dev, "Unsupported transaction %d\n", size);
                return -EOPNOTSUPP;
        }

        sis5595_write(SMB_CTL_LO, ((size & 0x0E)));

        status = sis5595_transaction(adap);
        if (status)
                return status;

        if ((size != SIS5595_PROC_CALL) &&
            ((read_write == I2C_SMBUS_WRITE) || (size == SIS5595_QUICK)))
                return 0;


        switch (size) {
        case SIS5595_BYTE:
        case SIS5595_BYTE_DATA:
                data->byte = sis5595_read(SMB_BYTE);
                break;
        case SIS5595_WORD_DATA:
        case SIS5595_PROC_CALL:
                data->word = sis5595_read(SMB_BYTE) + (sis5595_read(SMB_BYTE + 1) << 8);
                break;
        }
        return 0;
}

static u32 sis5595_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_PROC_CALL;
}

static const struct i2c_algorithm smbus_algorithm = {
        .smbus_xfer     = sis5595_access,
        .functionality  = sis5595_func,
};

static struct i2c_adapter sis5595_adapter = {
        .owner          = THIS_MODULE,
        .class          = I2C_CLASS_HWMON | I2C_CLASS_SPD,
        .algo           = &smbus_algorithm,
};

static const struct pci_device_id sis5595_ids[] = {
        { PCI_DEVICE(PCI_VENDOR_ID_SI, PCI_DEVICE_ID_SI_503) }, 
        { 0, }
};

MODULE_DEVICE_TABLE (pci, sis5595_ids);

static int sis5595_probe(struct pci_dev *dev, const struct pci_device_id *id)
{
        int err;

        if (sis5595_setup(dev)) {
                dev_err(&dev->dev, "SIS5595 not detected, module not inserted.\n");
                return -ENODEV;
        }

        /* set up the sysfs linkage to our parent device */
        sis5595_adapter.dev.parent = &dev->dev;

        snprintf(sis5595_adapter.name, sizeof(sis5595_adapter.name),
                 "SMBus SIS5595 adapter at %04x", sis5595_base + SMB_INDEX);
        err = i2c_add_adapter(&sis5595_adapter);
        if (err) {
                release_region(sis5595_base + SMB_INDEX, 2);
                return err;
        }

        /* Always return failure here.  This is to allow other drivers to bind
         * to this pci device.  We don't really want to have control over the
         * pci device, we only wanted to read as few register values from it.
         */
        sis5595_pdev =  pci_dev_get(dev);
        return -ENODEV;
}

static struct pci_driver sis5595_driver = {
        .name           = "sis5595_smbus",
        .id_table       = sis5595_ids,
        .probe          = sis5595_probe,
};

static int __init i2c_sis5595_init(void)
{
        return pci_register_driver(&sis5595_driver);
}

static void __exit i2c_sis5595_exit(void)
{
        pci_unregister_driver(&sis5595_driver);
        if (sis5595_pdev) {
                i2c_del_adapter(&sis5595_adapter);
                release_region(sis5595_base + SMB_INDEX, 2);
                pci_dev_put(sis5595_pdev);
                sis5595_pdev = NULL;
        }
}

MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
MODULE_DESCRIPTION("SIS5595 SMBus driver");
MODULE_LICENSE("GPL");

module_init(i2c_sis5595_init);
module_exit(i2c_sis5595_exit);