// SPDX-License-Identifier: GPL-2.0-only
/*
 * Coral-P(A)/Lime I2C adapter driver
 *
 * (C) 2011 DENX Software Engineering, Anatolij Gustschin <agust@denx.de>
 */

#include <linux/fb.h>
#include <linux/i2c.h>
#include <linux/io.h>
#include <linux/delay.h>

#include "mb862xxfb.h"
#include "mb862xx_reg.h"

static int mb862xx_i2c_wait_event(struct i2c_adapter *adap)
{
        struct mb862xxfb_par *par = adap->algo_data;
        u32 reg;

        do {
                udelay(10);
                reg = inreg(i2c, GC_I2C_BCR);
                if (reg & (I2C_INT | I2C_BER))
                        break;
        } while (1);

        return (reg & I2C_BER) ? 0 : 1;
}

static int mb862xx_i2c_do_address(struct i2c_adapter *adap, int addr)
{
        struct mb862xxfb_par *par = adap->algo_data;

        outreg(i2c, GC_I2C_DAR, addr);
        outreg(i2c, GC_I2C_CCR, I2C_CLOCK_AND_ENABLE);
        outreg(i2c, GC_I2C_BCR, par->i2c_rs ? I2C_REPEATED_START : I2C_START);
        if (!mb862xx_i2c_wait_event(adap))
                return -EIO;
        par->i2c_rs = !(inreg(i2c, GC_I2C_BSR) & I2C_LRB);
        return par->i2c_rs;
}

static int mb862xx_i2c_write_byte(struct i2c_adapter *adap, u8 byte)
{
        struct mb862xxfb_par *par = adap->algo_data;

        outreg(i2c, GC_I2C_DAR, byte);
        outreg(i2c, GC_I2C_BCR, I2C_START);
        if (!mb862xx_i2c_wait_event(adap))
                return -EIO;
        return !(inreg(i2c, GC_I2C_BSR) & I2C_LRB);
}

static int mb862xx_i2c_read_byte(struct i2c_adapter *adap, u8 *byte, int last)
{
        struct mb862xxfb_par *par = adap->algo_data;

        outreg(i2c, GC_I2C_BCR, I2C_START | (last ? 0 : I2C_ACK));
        if (!mb862xx_i2c_wait_event(adap))
                return 0;
        *byte = inreg(i2c, GC_I2C_DAR);
        return 1;
}

static void mb862xx_i2c_stop(struct i2c_adapter *adap)
{
        struct mb862xxfb_par *par = adap->algo_data;

        outreg(i2c, GC_I2C_BCR, I2C_STOP);
        outreg(i2c, GC_I2C_CCR, I2C_DISABLE);
        par->i2c_rs = 0;
}

static int mb862xx_i2c_read(struct i2c_adapter *adap, struct i2c_msg *m)
{
        int i, ret = 0;
        int last = m->len - 1;

        for (i = 0; i < m->len; i++) {
                if (!mb862xx_i2c_read_byte(adap, &m->buf[i], i == last)) {
                        ret = -EIO;
                        break;
                }
        }
        return ret;
}

static int mb862xx_i2c_write(struct i2c_adapter *adap, struct i2c_msg *m)
{
        int i, ret = 0;

        for (i = 0; i < m->len; i++) {
                if (!mb862xx_i2c_write_byte(adap, m->buf[i])) {
                        ret = -EIO;
                        break;
                }
        }
        return ret;
}

static int mb862xx_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
                        int num)
{
        struct mb862xxfb_par *par = adap->algo_data;
        struct i2c_msg *m;
        int addr;
        int i = 0, err = 0;

        dev_dbg(par->dev, "%s: %d msgs\n", __func__, num);

        for (i = 0; i < num; i++) {
                m = &msgs[i];
                if (!m->len) {
                        dev_dbg(par->dev, "%s: null msgs\n", __func__);
                        continue;
                }
                addr = m->addr;
                if (m->flags & I2C_M_RD)
                        addr |= 1;

                err = mb862xx_i2c_do_address(adap, addr);
                if (err < 0)
                        break;
                if (m->flags & I2C_M_RD)
                        err = mb862xx_i2c_read(adap, m);
                else
                        err = mb862xx_i2c_write(adap, m);
        }

        if (i)
                mb862xx_i2c_stop(adap);

        return (err < 0) ? err : i;
}

static u32 mb862xx_func(struct i2c_adapter *adap)
{
        return I2C_FUNC_SMBUS_BYTE_DATA;
}

static const struct i2c_algorithm mb862xx_algo = {
        .master_xfer    = mb862xx_xfer,
        .functionality  = mb862xx_func,
};

static struct i2c_adapter mb862xx_i2c_adapter = {
        .name           = "MB862xx I2C adapter",
        .algo           = &mb862xx_algo,
        .owner          = THIS_MODULE,
};

int mb862xx_i2c_init(struct mb862xxfb_par *par)
{
        mb862xx_i2c_adapter.algo_data = par;
        par->adap = &mb862xx_i2c_adapter;

        return i2c_add_adapter(par->adap);
}

void mb862xx_i2c_exit(struct mb862xxfb_par *par)
{
        if (par->adap) {
                i2c_del_adapter(par->adap);
                par->adap = NULL;
        }
}