// SPDX-License-Identifier: GPL-2.0
/*
 * Linux driver for digital TV devices equipped with B2C2 FlexcopII(b)/III
 * flexcop-i2c.c - flexcop internal 2Wire bus (I2C) and dvb i2c initialization
 * see flexcop.c for copyright information
 */
#include "flexcop.h"

#define FC_MAX_I2C_RETRIES 100000

static int flexcop_i2c_operation(struct flexcop_device *fc,
                flexcop_ibi_value *r100)
{
        int i;
        flexcop_ibi_value r;

        r100->tw_sm_c_100.working_start = 1;
        deb_i2c("r100 before: %08x\n",r100->raw);

        fc->write_ibi_reg(fc, tw_sm_c_100, ibi_zero);
        fc->write_ibi_reg(fc, tw_sm_c_100, *r100); /* initiating i2c operation */

        for (i = 0; i < FC_MAX_I2C_RETRIES; i++) {
                r = fc->read_ibi_reg(fc, tw_sm_c_100);

                if (!r.tw_sm_c_100.no_base_addr_ack_error) {
                        if (r.tw_sm_c_100.st_done) {
                                *r100 = r;
                                deb_i2c("i2c success\n");
                                return 0;
                        }
                } else {
                        deb_i2c("suffering from an i2c ack_error\n");
                        return -EREMOTEIO;
                }
        }
        deb_i2c("tried %d times i2c operation, never finished or too many ack errors.\n",
                i);
        return -EREMOTEIO;
}

static int flexcop_i2c_read4(struct flexcop_i2c_adapter *i2c,
                flexcop_ibi_value r100, u8 *buf)
{
        flexcop_ibi_value r104;
        int len = r100.tw_sm_c_100.total_bytes,
                /* remember total_bytes is buflen-1 */
                ret;

        /* work-around to have CableStar2 and SkyStar2 rev 2.7 work
         * correctly:
         *
         * the ITD1000 is behind an i2c-gate which closes automatically
         * after an i2c-transaction the STV0297 needs 2 consecutive reads
         * one with no_base_addr = 0 and one with 1
         *
         * those two work-arounds are conflictin: we check for the card
         * type, it is set when probing the ITD1000 */
        if (i2c->fc->dev_type == FC_SKY_REV27)
                r100.tw_sm_c_100.no_base_addr_ack_error = i2c->no_base_addr;

        ret = flexcop_i2c_operation(i2c->fc, &r100);
        if (ret != 0) {
                deb_i2c("Retrying operation\n");
                r100.tw_sm_c_100.no_base_addr_ack_error = i2c->no_base_addr;
                ret = flexcop_i2c_operation(i2c->fc, &r100);
        }
        if (ret != 0) {
                deb_i2c("read failed. %d\n", ret);
                return ret;
        }

        buf[0] = r100.tw_sm_c_100.data1_reg;

        if (len > 0) {
                r104 = i2c->fc->read_ibi_reg(i2c->fc, tw_sm_c_104);
                deb_i2c("read: r100: %08x, r104: %08x\n", r100.raw, r104.raw);

                /* there is at least one more byte, otherwise we wouldn't be here */
                buf[1] = r104.tw_sm_c_104.data2_reg;
                if (len > 1) buf[2] = r104.tw_sm_c_104.data3_reg;
                if (len > 2) buf[3] = r104.tw_sm_c_104.data4_reg;
        }
        return 0;
}

static int flexcop_i2c_write4(struct flexcop_device *fc,
                flexcop_ibi_value r100, u8 *buf)
{
        flexcop_ibi_value r104;
        int len = r100.tw_sm_c_100.total_bytes; /* remember total_bytes is buflen-1 */
        r104.raw = 0;

        /* there is at least one byte, otherwise we wouldn't be here */
        r100.tw_sm_c_100.data1_reg = buf[0];
        r104.tw_sm_c_104.data2_reg = len > 0 ? buf[1] : 0;
        r104.tw_sm_c_104.data3_reg = len > 1 ? buf[2] : 0;
        r104.tw_sm_c_104.data4_reg = len > 2 ? buf[3] : 0;

        deb_i2c("write: r100: %08x, r104: %08x\n", r100.raw, r104.raw);

        /* write the additional i2c data before doing the actual i2c operation */
        fc->write_ibi_reg(fc, tw_sm_c_104, r104);
        return flexcop_i2c_operation(fc, &r100);
}

int flexcop_i2c_request(struct flexcop_i2c_adapter *i2c,
                        flexcop_access_op_t op, u8 chipaddr,
                        u8 start_addr, u8 *buf, u16 size)
{
        int ret;
        int len = size;
        u8 *p;
        u8 addr = start_addr;

        u16 bytes_to_transfer;
        flexcop_ibi_value r100;

        deb_i2c("port %d %s(%02x): register %02x, size: %d\n",
                i2c->port,
                op == FC_READ ? "rd" : "wr",
                chipaddr, start_addr, size);
        r100.raw = 0;
        r100.tw_sm_c_100.chipaddr = chipaddr;
        r100.tw_sm_c_100.twoWS_rw = op;
        r100.tw_sm_c_100.twoWS_port_reg = i2c->port;

        /* in that case addr is the only value ->
         * we write it twice as baseaddr and val0
         * BBTI is doing it like that for ISL6421 at least */
        if (i2c->no_base_addr && len == 0 && op == FC_WRITE) {
                buf = &start_addr;
                len = 1;
        }

        p = buf;

        while (len != 0) {
                bytes_to_transfer = len > 4 ? 4 : len;

                r100.tw_sm_c_100.total_bytes = bytes_to_transfer - 1;
                r100.tw_sm_c_100.baseaddr = addr;

                if (op == FC_READ)
                        ret = flexcop_i2c_read4(i2c, r100, p);
                else
                        ret = flexcop_i2c_write4(i2c->fc, r100, p);

                if (ret < 0)
                        return ret;

                p  += bytes_to_transfer;
                addr += bytes_to_transfer;
                len  -= bytes_to_transfer;
        }
        deb_i2c_dump("port %d %s(%02x): register %02x: %*ph\n",
                i2c->port,
                op == FC_READ ? "rd" : "wr",
                chipaddr, start_addr, size, buf);

        return 0;
}
/* exported for PCI i2c */
EXPORT_SYMBOL(flexcop_i2c_request);

/* master xfer callback for demodulator */
static int flexcop_master_xfer(struct i2c_adapter *i2c_adap,
                struct i2c_msg msgs[], int num)
{
        struct flexcop_i2c_adapter *i2c = i2c_get_adapdata(i2c_adap);
        int i, ret = 0;

        /* Some drivers use 1 byte or 0 byte reads as probes, which this
         * driver doesn't support.  These probes will always fail, so this
         * hack makes them always succeed.  If one knew how, it would of
         * course be better to actually do the read.  */
        if (num == 1 && msgs[0].flags == I2C_M_RD && msgs[0].len <= 1)
                return 1;

        if (mutex_lock_interruptible(&i2c->fc->i2c_mutex))
                return -ERESTARTSYS;

        for (i = 0; i < num; i++) {
                /* reading */
                if (i+1 < num && (msgs[i+1].flags == I2C_M_RD)) {
                        ret = i2c->fc->i2c_request(i2c, FC_READ, msgs[i].addr,
                                        msgs[i].buf[0], msgs[i+1].buf,
                                        msgs[i+1].len);
                        i++; /* skip the following message */
                } else /* writing */
                        ret = i2c->fc->i2c_request(i2c, FC_WRITE, msgs[i].addr,
                                        msgs[i].buf[0], &msgs[i].buf[1],
                                        msgs[i].len - 1);
                if (ret < 0) {
                        deb_i2c("i2c master_xfer failed");
                        break;
                }
        }

        mutex_unlock(&i2c->fc->i2c_mutex);

        if (ret == 0)
                ret = num;
        return ret;
}

static u32 flexcop_i2c_func(struct i2c_adapter *adapter)
{
        return I2C_FUNC_I2C;
}

static const struct i2c_algorithm flexcop_algo = {
        .master_xfer    = flexcop_master_xfer,
        .functionality  = flexcop_i2c_func,
};

int flexcop_i2c_init(struct flexcop_device *fc)
{
        int ret;
        mutex_init(&fc->i2c_mutex);

        fc->fc_i2c_adap[0].fc = fc;
        fc->fc_i2c_adap[1].fc = fc;
        fc->fc_i2c_adap[2].fc = fc;
        fc->fc_i2c_adap[0].port = FC_I2C_PORT_DEMOD;
        fc->fc_i2c_adap[1].port = FC_I2C_PORT_EEPROM;
        fc->fc_i2c_adap[2].port = FC_I2C_PORT_TUNER;

        strscpy(fc->fc_i2c_adap[0].i2c_adap.name, "B2C2 FlexCop I2C to demod",
                sizeof(fc->fc_i2c_adap[0].i2c_adap.name));
        strscpy(fc->fc_i2c_adap[1].i2c_adap.name, "B2C2 FlexCop I2C to eeprom",
                sizeof(fc->fc_i2c_adap[1].i2c_adap.name));
        strscpy(fc->fc_i2c_adap[2].i2c_adap.name, "B2C2 FlexCop I2C to tuner",
                sizeof(fc->fc_i2c_adap[2].i2c_adap.name));

        i2c_set_adapdata(&fc->fc_i2c_adap[0].i2c_adap, &fc->fc_i2c_adap[0]);
        i2c_set_adapdata(&fc->fc_i2c_adap[1].i2c_adap, &fc->fc_i2c_adap[1]);
        i2c_set_adapdata(&fc->fc_i2c_adap[2].i2c_adap, &fc->fc_i2c_adap[2]);

        fc->fc_i2c_adap[0].i2c_adap.algo =
                fc->fc_i2c_adap[1].i2c_adap.algo =
                fc->fc_i2c_adap[2].i2c_adap.algo = &flexcop_algo;
        fc->fc_i2c_adap[0].i2c_adap.algo_data =
                fc->fc_i2c_adap[1].i2c_adap.algo_data =
                fc->fc_i2c_adap[2].i2c_adap.algo_data = NULL;
        fc->fc_i2c_adap[0].i2c_adap.dev.parent =
                fc->fc_i2c_adap[1].i2c_adap.dev.parent =
                fc->fc_i2c_adap[2].i2c_adap.dev.parent = fc->dev;

        ret = i2c_add_adapter(&fc->fc_i2c_adap[0].i2c_adap);
        if (ret < 0)
                return ret;

        ret = i2c_add_adapter(&fc->fc_i2c_adap[1].i2c_adap);
        if (ret < 0)
                goto adap_1_failed;

        ret = i2c_add_adapter(&fc->fc_i2c_adap[2].i2c_adap);
        if (ret < 0)
                goto adap_2_failed;

        fc->init_state |= FC_STATE_I2C_INIT;
        return 0;

adap_2_failed:
        i2c_del_adapter(&fc->fc_i2c_adap[1].i2c_adap);
adap_1_failed:
        i2c_del_adapter(&fc->fc_i2c_adap[0].i2c_adap);
        return ret;
}

void flexcop_i2c_exit(struct flexcop_device *fc)
{
        if (fc->init_state & FC_STATE_I2C_INIT) {
                i2c_del_adapter(&fc->fc_i2c_adap[2].i2c_adap);
                i2c_del_adapter(&fc->fc_i2c_adap[1].i2c_adap);
                i2c_del_adapter(&fc->fc_i2c_adap[0].i2c_adap);
        }
        fc->init_state &= ~FC_STATE_I2C_INIT;
}