// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      matrox_w1.c
 *
 * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
 */

#include <asm/types.h>
#include <linux/atomic.h>
#include <linux/io.h>

#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/timer.h>
#include <linux/slab.h>
#include <linux/pci_ids.h>
#include <linux/pci.h>

#include <linux/w1.h>

/*
 * Matrox G400 DDC registers.
 */

#define MATROX_G400_DDC_CLK             (1<<4)
#define MATROX_G400_DDC_DATA            (1<<1)

#define MATROX_BASE                     0x3C00
#define MATROX_STATUS                   0x1e14

#define MATROX_PORT_INDEX_OFFSET        0x00
#define MATROX_PORT_DATA_OFFSET         0x0A

#define MATROX_GET_CONTROL              0x2A
#define MATROX_GET_DATA                 0x2B
#define MATROX_CURSOR_CTL               0x06

struct matrox_device {
        void __iomem *base_addr;
        void __iomem *port_index;
        void __iomem *port_data;
        u8 data_mask;

        unsigned long phys_addr;
        void __iomem *virt_addr;

        struct w1_bus_master *bus_master;
};

/*
 * These functions read and write DDC Data bit.
 *
 * Using tristate pins, since i can't find any open-drain pin in whole motherboard.
 * Unfortunately we can't connect to Intel's 82801xx IO controller
 * since we don't know motherboard schema, which has pretty unused(may be not) GPIO.
 *
 * I've heard that PIIX also has open drain pin.
 *
 * Port mapping.
 */
static inline u8 matrox_w1_read_reg(struct matrox_device *dev, u8 reg)
{
        u8 ret;

        writeb(reg, dev->port_index);
        ret = readb(dev->port_data);
        barrier();

        return ret;
}

static inline void matrox_w1_write_reg(struct matrox_device *dev, u8 reg, u8 val)
{
        writeb(reg, dev->port_index);
        writeb(val, dev->port_data);
        wmb();
}

static void matrox_w1_write_ddc_bit(void *data, u8 bit)
{
        u8 ret;
        struct matrox_device *dev = data;

        if (bit)
                bit = 0;
        else
                bit = dev->data_mask;

        ret = matrox_w1_read_reg(dev, MATROX_GET_CONTROL);
        matrox_w1_write_reg(dev, MATROX_GET_CONTROL, ((ret & ~dev->data_mask) | bit));
        matrox_w1_write_reg(dev, MATROX_GET_DATA, 0x00);
}

static u8 matrox_w1_read_ddc_bit(void *data)
{
        u8 ret;
        struct matrox_device *dev = data;

        ret = matrox_w1_read_reg(dev, MATROX_GET_DATA);

        return ret;
}

static void matrox_w1_hw_init(struct matrox_device *dev)
{
        matrox_w1_write_reg(dev, MATROX_GET_DATA, 0xFF);
        matrox_w1_write_reg(dev, MATROX_GET_CONTROL, 0x00);
}

static int matrox_w1_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
{
        struct matrox_device *dev;
        int err;

        if (pdev->vendor != PCI_VENDOR_ID_MATROX || pdev->device != PCI_DEVICE_ID_MATROX_G400)
                return -ENODEV;

        dev = kzalloc(sizeof(struct matrox_device) +
                       sizeof(struct w1_bus_master), GFP_KERNEL);
        if (!dev)
                return -ENOMEM;

        dev->bus_master = (struct w1_bus_master *)(dev + 1);

        /*
         * True for G400, for some other we need resource 0, see drivers/video/matrox/matroxfb_base.c
         */

        dev->phys_addr = pci_resource_start(pdev, 1);

        dev->virt_addr = ioremap(dev->phys_addr, 16384);
        if (!dev->virt_addr) {
                dev_err(&pdev->dev, "%s: failed to ioremap(0x%lx, %d).\n",
                        __func__, dev->phys_addr, 16384);
                err = -EIO;
                goto err_out_free_device;
        }

        dev->base_addr = dev->virt_addr + MATROX_BASE;
        dev->port_index = dev->base_addr + MATROX_PORT_INDEX_OFFSET;
        dev->port_data = dev->base_addr + MATROX_PORT_DATA_OFFSET;
        dev->data_mask = (MATROX_G400_DDC_DATA);

        matrox_w1_hw_init(dev);

        dev->bus_master->data = dev;
        dev->bus_master->read_bit = &matrox_w1_read_ddc_bit;
        dev->bus_master->write_bit = &matrox_w1_write_ddc_bit;

        err = w1_add_master_device(dev->bus_master);
        if (err)
                goto err_out_free_device;

        pci_set_drvdata(pdev, dev);

        dev_info(&pdev->dev, "Matrox G400 GPIO transport layer for 1-wire.\n");

        return 0;

err_out_free_device:
        if (dev->virt_addr)
                iounmap(dev->virt_addr);
        kfree(dev);

        return err;
}

static void matrox_w1_remove(struct pci_dev *pdev)
{
        struct matrox_device *dev = pci_get_drvdata(pdev);

        w1_remove_master_device(dev->bus_master);
        iounmap(dev->virt_addr);

        kfree(dev);
}

static struct pci_device_id matrox_w1_tbl[] = {
        { PCI_DEVICE(PCI_VENDOR_ID_MATROX, PCI_DEVICE_ID_MATROX_G400) },
        { },
};
MODULE_DEVICE_TABLE(pci, matrox_w1_tbl);

static struct pci_driver matrox_w1_pci_driver = {
        .name = "matrox_w1",
        .id_table = matrox_w1_tbl,
        .probe = matrox_w1_probe,
        .remove = matrox_w1_remove,
};
module_pci_driver(matrox_w1_pci_driver);

MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
MODULE_DESCRIPTION("Driver for transport(Dallas 1-wire protocol) over VGA DDC(matrox gpio).");
MODULE_LICENSE("GPL");