// SPDX-License-Identifier: GPL-2.0-or-later
/*
    i2c Support for Via Technologies 82C586B South Bridge

    Copyright (c) 1998, 1999 Kyösti Mälkki <kmalkki@cc.hut.fi>

*/

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/ioport.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>
#include <linux/io.h>

/* Power management registers */
#define PM_CFG_REVID    0x08    /* silicon revision code */
#define PM_CFG_IOBASE0  0x20
#define PM_CFG_IOBASE1  0x48

#define I2C_DIR         (pm_io_base+0x40)
#define I2C_OUT         (pm_io_base+0x42)
#define I2C_IN          (pm_io_base+0x44)
#define I2C_SCL         0x02    /* clock bit in DIR/OUT/IN register */
#define I2C_SDA         0x04

/* io-region reservation */
#define IOSPACE         0x06

static struct pci_driver vt586b_driver;
static u16 pm_io_base;

/*
   It does not appear from the datasheet that the GPIO pins are
   open drain. So a we set a low value by setting the direction to
   output and a high value by setting the direction to input and
   relying on the required I2C pullup. The data value is initialized
   to 0 in via_init() and never changed.
*/
static void bit_via_setscl(void *data, int state)
{
        outb(state ? inb(I2C_DIR) & ~I2C_SCL : inb(I2C_DIR) | I2C_SCL, I2C_DIR);
}

static void bit_via_setsda(void *data, int state)
{
        outb(state ? inb(I2C_DIR) & ~I2C_SDA : inb(I2C_DIR) | I2C_SDA, I2C_DIR);
}

static int bit_via_getscl(void *data)
{
        return (0 != (inb(I2C_IN) & I2C_SCL));
}

static int bit_via_getsda(void *data)
{
        return (0 != (inb(I2C_IN) & I2C_SDA));
}


static struct i2c_algo_bit_data bit_data = {
        .setsda         = bit_via_setsda,
        .setscl         = bit_via_setscl,
        .getsda         = bit_via_getsda,
        .getscl         = bit_via_getscl,
        .udelay         = 5,
        .timeout        = HZ
};

static struct i2c_adapter vt586b_adapter = {
        .owner          = THIS_MODULE,
        .class          = I2C_CLASS_HWMON,
        .name           = "VIA i2c",
        .algo_data      = &bit_data,
};


static const struct pci_device_id vt586b_ids[] = {
        { PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C586_3) },
        { 0, }
};

MODULE_DEVICE_TABLE (pci, vt586b_ids);

static int vt586b_probe(struct pci_dev *dev, const struct pci_device_id *id)
{
        u16 base;
        u8 rev;
        int res;

        if (pm_io_base)
                return dev_err_probe(&dev->dev, -ENODEV,
                                     "Will only support one host\n");

        pci_read_config_byte(dev, PM_CFG_REVID, &rev);

        switch (rev) {
        case 0x00:
                base = PM_CFG_IOBASE0;
                break;
        case 0x01:
        case 0x10:
                base = PM_CFG_IOBASE1;
                break;

        default:
                base = PM_CFG_IOBASE1;
                /* later revision */
        }

        pci_read_config_word(dev, base, &pm_io_base);
        pm_io_base &= (0xff << 8);

        if (!request_region(I2C_DIR, IOSPACE, vt586b_driver.name))
                return dev_err_probe(&dev->dev, -ENODEV,
                                     "IO 0x%x-0x%x already in use\n",
                                     I2C_DIR, I2C_DIR + IOSPACE);

        outb(inb(I2C_DIR) & ~(I2C_SDA | I2C_SCL), I2C_DIR);
        outb(inb(I2C_OUT) & ~(I2C_SDA | I2C_SCL), I2C_OUT);

        /* set up the sysfs linkage to our parent device */
        vt586b_adapter.dev.parent = &dev->dev;

        res = i2c_bit_add_bus(&vt586b_adapter);
        if ( res < 0 ) {
                release_region(I2C_DIR, IOSPACE);
                pm_io_base = 0;
                return res;
        }
        return 0;
}

static void vt586b_remove(struct pci_dev *dev)
{
        i2c_del_adapter(&vt586b_adapter);
        release_region(I2C_DIR, IOSPACE);
        pm_io_base = 0;
}


static struct pci_driver vt586b_driver = {
        .name           = "vt586b_smbus",
        .id_table       = vt586b_ids,
        .probe          = vt586b_probe,
        .remove         = vt586b_remove,
};

module_pci_driver(vt586b_driver);

MODULE_AUTHOR("Kyösti Mälkki <kmalkki@cc.hut.fi>");
MODULE_DESCRIPTION("i2c for Via vt82c586b southbridge");
MODULE_LICENSE("GPL");