// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2004 Steven J. Hill
 * Copyright (C) 2001,2002,2003 Broadcom Corporation
 * Copyright (C) 1995-2000 Simon G. Vogl
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/io.h>
#include <asm/sibyte/sb1250_regs.h>
#include <asm/sibyte/sb1250_smbus.h>


struct i2c_algo_sibyte_data {
        void *data;             /* private data */
        int   bus;              /* which bus */
        void *reg_base;         /* CSR base */
};

/* ----- global defines ----------------------------------------------- */
#define SMB_CSR(a,r) ((long)(a->reg_base + r))


static int smbus_xfer(struct i2c_adapter *i2c_adap, u16 addr,
                      unsigned short flags, char read_write,
                      u8 command, int size, union i2c_smbus_data * data)
{
        struct i2c_algo_sibyte_data *adap = i2c_adap->algo_data;
        int data_bytes = 0;
        int error;

        while (csr_in32(SMB_CSR(adap, R_SMB_STATUS)) & M_SMB_BUSY)
                ;

        switch (size) {
        case I2C_SMBUS_QUICK:
                csr_out32((V_SMB_ADDR(addr) |
                           (read_write == I2C_SMBUS_READ ? M_SMB_QDATA : 0) |
                           V_SMB_TT_QUICKCMD), SMB_CSR(adap, R_SMB_START));
                break;
        case I2C_SMBUS_BYTE:
                if (read_write == I2C_SMBUS_READ) {
                        csr_out32((V_SMB_ADDR(addr) | V_SMB_TT_RD1BYTE),
                                  SMB_CSR(adap, R_SMB_START));
                        data_bytes = 1;
                } else {
                        csr_out32(V_SMB_CMD(command), SMB_CSR(adap, R_SMB_CMD));
                        csr_out32((V_SMB_ADDR(addr) | V_SMB_TT_WR1BYTE),
                                  SMB_CSR(adap, R_SMB_START));
                }
                break;
        case I2C_SMBUS_BYTE_DATA:
                csr_out32(V_SMB_CMD(command), SMB_CSR(adap, R_SMB_CMD));
                if (read_write == I2C_SMBUS_READ) {
                        csr_out32((V_SMB_ADDR(addr) | V_SMB_TT_CMD_RD1BYTE),
                                  SMB_CSR(adap, R_SMB_START));
                        data_bytes = 1;
                } else {
                        csr_out32(V_SMB_LB(data->byte),
                                  SMB_CSR(adap, R_SMB_DATA));
                        csr_out32((V_SMB_ADDR(addr) | V_SMB_TT_WR2BYTE),
                                  SMB_CSR(adap, R_SMB_START));
                }
                break;
        case I2C_SMBUS_WORD_DATA:
                csr_out32(V_SMB_CMD(command), SMB_CSR(adap, R_SMB_CMD));
                if (read_write == I2C_SMBUS_READ) {
                        csr_out32((V_SMB_ADDR(addr) | V_SMB_TT_CMD_RD2BYTE),
                                  SMB_CSR(adap, R_SMB_START));
                        data_bytes = 2;
                } else {
                        csr_out32(V_SMB_LB(data->word & 0xff),
                                  SMB_CSR(adap, R_SMB_DATA));
                        csr_out32(V_SMB_MB(data->word >> 8),
                                  SMB_CSR(adap, R_SMB_DATA));
                        csr_out32((V_SMB_ADDR(addr) | V_SMB_TT_WR2BYTE),
                                  SMB_CSR(adap, R_SMB_START));
                }
                break;
        default:
                return -EOPNOTSUPP;
        }

        while (csr_in32(SMB_CSR(adap, R_SMB_STATUS)) & M_SMB_BUSY)
                ;

        error = csr_in32(SMB_CSR(adap, R_SMB_STATUS));
        if (error & M_SMB_ERROR) {
                /* Clear error bit by writing a 1 */
                csr_out32(M_SMB_ERROR, SMB_CSR(adap, R_SMB_STATUS));
                return (error & M_SMB_ERROR_TYPE) ? -EIO : -ENXIO;
        }

        if (data_bytes == 1)
                data->byte = csr_in32(SMB_CSR(adap, R_SMB_DATA)) & 0xff;
        if (data_bytes == 2)
                data->word = csr_in32(SMB_CSR(adap, R_SMB_DATA)) & 0xffff;

        return 0;
}

static u32 bit_func(struct i2c_adapter *adap)
{
        return (I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
                I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA);
}


/* -----exported algorithm data: -------------------------------------  */

static const struct i2c_algorithm i2c_sibyte_algo = {
        .smbus_xfer     = smbus_xfer,
        .functionality  = bit_func,
};

/*
 * registering functions to load algorithms at runtime
 */
static int __init i2c_sibyte_add_bus(struct i2c_adapter *i2c_adap, int speed)
{
        struct i2c_algo_sibyte_data *adap = i2c_adap->algo_data;

        /* Register new adapter to i2c module... */
        i2c_adap->algo = &i2c_sibyte_algo;

        /* Set the requested frequency. */
        csr_out32(speed, SMB_CSR(adap,R_SMB_FREQ));
        csr_out32(0, SMB_CSR(adap,R_SMB_CONTROL));

        return i2c_add_numbered_adapter(i2c_adap);
}


static struct i2c_algo_sibyte_data sibyte_board_data[2] = {
        { NULL, 0, (void *) (CKSEG1+A_SMB_BASE(0)) },
        { NULL, 1, (void *) (CKSEG1+A_SMB_BASE(1)) }
};

static struct i2c_adapter sibyte_board_adapter[2] = {
        {
                .owner          = THIS_MODULE,
                .class          = I2C_CLASS_HWMON,
                .algo           = NULL,
                .algo_data      = &sibyte_board_data[0],
                .nr             = 0,
                .name           = "SiByte SMBus 0",
        },
        {
                .owner          = THIS_MODULE,
                .class          = I2C_CLASS_HWMON,
                .algo           = NULL,
                .algo_data      = &sibyte_board_data[1],
                .nr             = 1,
                .name           = "SiByte SMBus 1",
        },
};

static int __init i2c_sibyte_init(void)
{
        pr_info("i2c-sibyte: i2c SMBus adapter module for SiByte board\n");
        if (i2c_sibyte_add_bus(&sibyte_board_adapter[0], K_SMB_FREQ_100KHZ) < 0)
                return -ENODEV;
        if (i2c_sibyte_add_bus(&sibyte_board_adapter[1],
                               K_SMB_FREQ_400KHZ) < 0) {
                i2c_del_adapter(&sibyte_board_adapter[0]);
                return -ENODEV;
        }
        return 0;
}

static void __exit i2c_sibyte_exit(void)
{
        i2c_del_adapter(&sibyte_board_adapter[0]);
        i2c_del_adapter(&sibyte_board_adapter[1]);
}

module_init(i2c_sibyte_init);
module_exit(i2c_sibyte_exit);

MODULE_AUTHOR("Kip Walker (Broadcom Corp.)");
MODULE_AUTHOR("Steven J. Hill <sjhill@realitydiluted.com>");
MODULE_DESCRIPTION("SMBus adapter routines for SiByte boards");
MODULE_LICENSE("GPL");