// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * i2c-algo-pcf.c i2c driver algorithms for PCF8584 adapters
 *
 *   Copyright (C) 1995-1997 Simon G. Vogl
 *                 1998-2000 Hans Berglund
 *
 * With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
 * Frodo Looijaard <frodol@dds.nl>, and also from Martin Bailey
 * <mbailey@littlefeet-inc.com>
 *
 * Partially rewriten by Oleg I. Vdovikin <vdovikin@jscc.ru> to handle multiple
 * messages, proper stop/repstart signaling during receive, added detect code
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-pcf.h>
#include <linux/string_choices.h>
#include "i2c-algo-pcf.h"


#define DEF_TIMEOUT 16

/* setting states on the bus with the right timing: */

#define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val)
#define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl)
#define get_own(adap) adap->getown(adap->data)
#define get_clock(adap) adap->getclock(adap->data)
#define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val)
#define i2c_inb(adap) adap->getpcf(adap->data, 0)

/* other auxiliary functions */

static void i2c_start(struct i2c_algo_pcf_data *adap)
{
        set_pcf(adap, 1, I2C_PCF_START);
}

static void i2c_repstart(struct i2c_algo_pcf_data *adap)
{
        set_pcf(adap, 1, I2C_PCF_REPSTART);
}

static void i2c_stop(struct i2c_algo_pcf_data *adap)
{
        set_pcf(adap, 1, I2C_PCF_STOP);
}

static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status)
{
        /*
         * Cleanup from LAB -- reset and enable ESO.
         * This resets the PCF8584; since we've lost the bus, no
         * further attempts should be made by callers to clean up
         * (no i2c_stop() etc.)
         */
        set_pcf(adap, 1, I2C_PCF_PIN);
        set_pcf(adap, 1, I2C_PCF_ESO);
        /*
         * We pause for a time period sufficient for any running
         * I2C transaction to complete -- the arbitration logic won't
         * work properly until the next START is seen.
         * It is assumed the bus driver or client has set a proper value.
         *
         * REVISIT: should probably use msleep instead of mdelay if we
         * know we can sleep.
         */
        if (adap->lab_mdelay)
                mdelay(adap->lab_mdelay);

}

static int wait_for_bb(struct i2c_algo_pcf_data *adap)
{

        int timeout = DEF_TIMEOUT;
        int status;

        status = get_pcf(adap, 1);

        while (!(status & I2C_PCF_BB) && --timeout) {
                udelay(100); /* wait for 100 us */
                status = get_pcf(adap, 1);
        }

        if (timeout == 0) {
                printk(KERN_ERR "Timeout waiting for Bus Busy\n");
                return -ETIMEDOUT;
        }

        return 0;
}

static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status)
{

        int timeout = DEF_TIMEOUT;

        *status = get_pcf(adap, 1);

        while ((*status & I2C_PCF_PIN) && --timeout) {
                adap->waitforpin(adap->data);
                *status = get_pcf(adap, 1);
        }
        if (*status & I2C_PCF_LAB) {
                handle_lab(adap, status);
                return -EINTR;
        }

        if (timeout == 0)
                return -ETIMEDOUT;

        return 0;
}

/*
 * This should perform the 'PCF8584 initialization sequence' as described
 * in the Philips IC12 data book (1995, Aug 29).
 * There should be a 30 clock cycle wait after reset, I assume this
 * has been fulfilled.
 * There should be a delay at the end equal to the longest I2C message
 * to synchronize the BB-bit (in multimaster systems). How long is
 * this? I assume 1 second is always long enough.
 *
 * vdovikin: added detect code for PCF8584
 */
static int pcf_init_8584(struct i2c_algo_pcf_data *adap)
{
        unsigned char temp;

        /* S1=0x80: S0 selected, serial interface off */
        set_pcf(adap, 1, I2C_PCF_PIN);
        /*
         * check to see S1 now used as R/W ctrl -
         * PCF8584 does that when ESO is zero
         */
        temp = get_pcf(adap, 1);
        if ((temp & 0x7f) != 0)
                return -ENXIO; /* definitely not PCF8584 */

        /* load own address in S0, effective address is (own << 1) */
        i2c_outb(adap, get_own(adap));
        /* check it's really written */
        temp = i2c_inb(adap);
        if (temp != get_own(adap))
                return -ENXIO;

        /* S1=0xA0, next byte in S2 */
        set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1);
        /* check to see S2 now selected */
        temp = get_pcf(adap, 1);
        if ((temp & 0x7f) != I2C_PCF_ES1)
                return -ENXIO;

        /* load clock register S2 */
        i2c_outb(adap, get_clock(adap));
        /* check it's really written, the only 5 lowest bits does matter */
        temp = i2c_inb(adap);
        if ((temp & 0x1f) != get_clock(adap))
                return -ENXIO;

        /* Enable serial interface, idle, S0 selected */
        set_pcf(adap, 1, I2C_PCF_IDLE);

        /* check to see PCF is really idled and we can access status register */
        temp = get_pcf(adap, 1);
        if (temp != (I2C_PCF_PIN | I2C_PCF_BB))
                return -ENXIO;

        printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n");

        return 0;
}

static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf,
                         int count, int last)
{
        struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
        int wrcount, status, timeout;

        for (wrcount = 0; wrcount < count; ++wrcount) {
                i2c_outb(adap, buf[wrcount]);
                timeout = wait_for_pin(adap, &status);
                if (timeout) {
                        if (timeout == -EINTR)
                                return -EINTR; /* arbitration lost */

                        i2c_stop(adap);
                        dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
                        return -EREMOTEIO; /* got a better one ?? */
                }
                if (status & I2C_PCF_LRB) {
                        i2c_stop(adap);
                        dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
                        return -EREMOTEIO; /* got a better one ?? */
                }
        }
        if (last)
                i2c_stop(adap);
        else
                i2c_repstart(adap);

        return wrcount;
}

static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,
                         int count, int last)
{
        int i, status;
        struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
        int wfp;

        /* increment number of bytes to read by one -- read dummy byte */
        for (i = 0; i <= count; i++) {

                wfp = wait_for_pin(adap, &status);
                if (wfp) {
                        if (wfp == -EINTR)
                                return -EINTR; /* arbitration lost */

                        i2c_stop(adap);
                        dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
                        return -1;
                }

                if ((status & I2C_PCF_LRB) && (i != count)) {
                        i2c_stop(adap);
                        dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
                        return -1;
                }

                if (i == count - 1) {
                        set_pcf(adap, 1, I2C_PCF_ESO);
                } else if (i == count) {
                        if (last)
                                i2c_stop(adap);
                        else
                                i2c_repstart(adap);
                }

                if (i)
                        buf[i - 1] = i2c_inb(adap);
                else
                        i2c_inb(adap); /* dummy read */
        }

        return i - 1;
}


static void pcf_send_address(struct i2c_algo_pcf_data *adap,
                         struct i2c_msg *msg)
{
        unsigned char addr = i2c_8bit_addr_from_msg(msg);

        if (msg->flags & I2C_M_REV_DIR_ADDR)
                addr ^= 1;
        i2c_outb(adap, addr);
}

static int pcf_xfer(struct i2c_adapter *i2c_adap,
                    struct i2c_msg *msgs,
                    int num)
{
        struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
        struct i2c_msg *pmsg;
        int i;
        int timeout, status;

        if (adap->xfer_begin)
                adap->xfer_begin(adap->data);

        /* Check for bus busy */
        timeout = wait_for_bb(adap);
        if (timeout) {
                i = -EIO;
                goto out;
        }

        for (i = 0; i < num; i++) {
                int ret;

                pmsg = &msgs[i];
                pcf_send_address(adap, pmsg);

                /* Send START */
                if (i == 0)
                        i2c_start(adap);

                /* Wait for PIN (pending interrupt NOT) */
                timeout = wait_for_pin(adap, &status);
                if (timeout) {
                        if (timeout == -EINTR) {
                                /* arbitration lost */
                                i = -EINTR;
                                goto out;
                        }
                        i2c_stop(adap);
                        i = -EREMOTEIO;
                        goto out;
                }

                /* Check LRB (last rcvd bit - slave ack) */
                if (status & I2C_PCF_LRB) {
                        i2c_stop(adap);
                        i = -EREMOTEIO;
                        goto out;
                }


                if (pmsg->flags & I2C_M_RD) {
                        ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,
                                            (i + 1 == num));
                } else {
                        ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,
                                            (i + 1 == num));
                }

                if (ret < 0)
                        goto out;
        }

out:
        if (adap->xfer_end)
                adap->xfer_end(adap->data);
        return i;
}

static u32 pcf_func(struct i2c_adapter *adap)
{
        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
               I2C_FUNC_PROTOCOL_MANGLING;
}

/* exported algorithm data: */
static const struct i2c_algorithm pcf_algo = {
        .xfer = pcf_xfer,
        .functionality = pcf_func,
};

/*
 * registering functions to load algorithms at runtime
 */
int i2c_pcf_add_bus(struct i2c_adapter *adap)
{
        struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;
        int rval;

        /* register new adapter to i2c module... */
        adap->algo = &pcf_algo;

        rval = pcf_init_8584(pcf_adap);
        if (rval)
                return rval;

        rval = i2c_add_adapter(adap);

        return rval;
}
EXPORT_SYMBOL(i2c_pcf_add_bus);

MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
MODULE_LICENSE("GPL");