/*
 *  i2c-algo-pca.c i2c driver algorithms for PCA9564 adapters
 *    Copyright (C) 2004 Arcom Control Systems
 *    Copyright (C) 2008 Pengutronix
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/delay.h>
#include <linux/jiffies.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-pca.h>

#define DEB1(fmt, args...) do { if (i2c_debug >= 1)                     \
                                 printk(KERN_DEBUG fmt, ## args); } while (0)
#define DEB2(fmt, args...) do { if (i2c_debug >= 2)                     \
                                 printk(KERN_DEBUG fmt, ## args); } while (0)
#define DEB3(fmt, args...) do { if (i2c_debug >= 3)                     \
                                 printk(KERN_DEBUG fmt, ## args); } while (0)

static int i2c_debug;

#define pca_outw(adap, reg, val) adap->write_byte(adap->data, reg, val)
#define pca_inw(adap, reg) adap->read_byte(adap->data, reg)

#define pca_status(adap) pca_inw(adap, I2C_PCA_STA)
#define pca_clock(adap) adap->i2c_clock
#define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val)
#define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON)
#define pca_wait(adap) adap->wait_for_completion(adap->data)

static void pca_reset(struct i2c_algo_pca_data *adap)
{
        if (adap->chip == I2C_PCA_CHIP_9665) {
                /* Ignore the reset function from the module,
                 * we can use the parallel bus reset.
                 */
                pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IPRESET);
                pca_outw(adap, I2C_PCA_IND, 0xA5);
                pca_outw(adap, I2C_PCA_IND, 0x5A);
        } else {
                adap->reset_chip(adap->data);
        }
}

/*
 * Generate a start condition on the i2c bus.
 *
 * returns after the start condition has occurred
 */
static int pca_start(struct i2c_algo_pca_data *adap)
{
        int sta = pca_get_con(adap);
        DEB2("=== START\n");
        sta |= I2C_PCA_CON_STA;
        sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
        pca_set_con(adap, sta);
        return pca_wait(adap);
}

/*
 * Generate a repeated start condition on the i2c bus
 *
 * return after the repeated start condition has occurred
 */
static int pca_repeated_start(struct i2c_algo_pca_data *adap)
{
        int sta = pca_get_con(adap);
        DEB2("=== REPEATED START\n");
        sta |= I2C_PCA_CON_STA;
        sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
        pca_set_con(adap, sta);
        return pca_wait(adap);
}

/*
 * Generate a stop condition on the i2c bus
 *
 * returns after the stop condition has been generated
 *
 * STOPs do not generate an interrupt or set the SI flag, since the
 * part returns the idle state (0xf8). Hence we don't need to
 * pca_wait here.
 */
static void pca_stop(struct i2c_algo_pca_data *adap)
{
        int sta = pca_get_con(adap);
        DEB2("=== STOP\n");
        sta |= I2C_PCA_CON_STO;
        sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI);
        pca_set_con(adap, sta);
}

/*
 * Send the slave address and R/W bit
 *
 * returns after the address has been sent
 */
static int pca_address(struct i2c_algo_pca_data *adap,
                       struct i2c_msg *msg)
{
        int sta = pca_get_con(adap);
        int addr;

        addr = ((0x7f & msg->addr) << 1);
        if (msg->flags & I2C_M_RD)
                addr |= 1;
        DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
             msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);

        pca_outw(adap, I2C_PCA_DAT, addr);

        sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
        pca_set_con(adap, sta);

        return pca_wait(adap);
}

/*
 * Transmit a byte.
 *
 * Returns after the byte has been transmitted
 */
static int pca_tx_byte(struct i2c_algo_pca_data *adap,
                       __u8 b)
{
        int sta = pca_get_con(adap);
        DEB2("=== WRITE %#04x\n", b);
        pca_outw(adap, I2C_PCA_DAT, b);

        sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
        pca_set_con(adap, sta);

        return pca_wait(adap);
}

/*
 * Receive a byte
 *
 * returns immediately.
 */
static void pca_rx_byte(struct i2c_algo_pca_data *adap,
                        __u8 *b, int ack)
{
        *b = pca_inw(adap, I2C_PCA_DAT);
        DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
}

/*
 * Setup ACK or NACK for next received byte and wait for it to arrive.
 *
 * Returns after next byte has arrived.
 */
static int pca_rx_ack(struct i2c_algo_pca_data *adap,
                      int ack)
{
        int sta = pca_get_con(adap);

        sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);

        if (ack)
                sta |= I2C_PCA_CON_AA;

        pca_set_con(adap, sta);
        return pca_wait(adap);
}

static int pca_xfer(struct i2c_adapter *i2c_adap,
                    struct i2c_msg *msgs,
                    int num)
{
        struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
        struct i2c_msg *msg = NULL;
        int curmsg;
        int numbytes = 0;
        int state;
        int ret;
        int completed = 1;
        unsigned long timeout = jiffies + i2c_adap->timeout;

        while ((state = pca_status(adap)) != 0xf8) {
                if (time_before(jiffies, timeout)) {
                        msleep(10);
                } else {
                        dev_dbg(&i2c_adap->dev, "bus is not idle. status is "
                                "%#04x\n", state);
                        return -EBUSY;
                }
        }

        DEB1("{{{ XFER %d messages\n", num);

        if (i2c_debug >= 2) {
                for (curmsg = 0; curmsg < num; curmsg++) {
                        int addr, i;
                        msg = &msgs[curmsg];

                        addr = (0x7f & msg->addr) ;

                        if (msg->flags & I2C_M_RD)
                                printk(KERN_INFO "    [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
                                       curmsg, msg->len, addr, (addr << 1) | 1);
                        else {
                                printk(KERN_INFO "    [%02d] WR %d bytes to %#02x [%#02x%s",
                                       curmsg, msg->len, addr, addr << 1,
                                       msg->len == 0 ? "" : ", ");
                                for (i = 0; i < msg->len; i++)
                                        printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
                                printk("]\n");
                        }
                }
        }

        curmsg = 0;
        ret = -EIO;
        while (curmsg < num) {
                state = pca_status(adap);

                DEB3("STATE is 0x%02x\n", state);
                msg = &msgs[curmsg];

                switch (state) {
                case 0xf8: /* On reset or stop the bus is idle */
                        completed = pca_start(adap);
                        break;

                case 0x08: /* A START condition has been transmitted */
                case 0x10: /* A repeated start condition has been transmitted */
                        completed = pca_address(adap, msg);
                        break;

                case 0x18: /* SLA+W has been transmitted; ACK has been received */
                case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
                        if (numbytes < msg->len) {
                                completed = pca_tx_byte(adap,
                                                        msg->buf[numbytes]);
                                numbytes++;
                                break;
                        }
                        curmsg++; numbytes = 0;
                        if (curmsg == num)
                                pca_stop(adap);
                        else
                                completed = pca_repeated_start(adap);
                        break;

                case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
                        DEB2("NOT ACK received after SLA+W\n");
                        pca_stop(adap);
                        ret = -ENXIO;
                        goto out;

                case 0x40: /* SLA+R has been transmitted; ACK has been received */
                        completed = pca_rx_ack(adap, msg->len > 1);
                        break;

                case 0x50: /* Data bytes has been received; ACK has been returned */
                        if (numbytes < msg->len) {
                                pca_rx_byte(adap, &msg->buf[numbytes], 1);
                                numbytes++;
                                completed = pca_rx_ack(adap,
                                                       numbytes < msg->len - 1);
                                break;
                        }
                        curmsg++; numbytes = 0;
                        if (curmsg == num)
                                pca_stop(adap);
                        else
                                completed = pca_repeated_start(adap);
                        break;

                case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
                        DEB2("NOT ACK received after SLA+R\n");
                        pca_stop(adap);
                        ret = -ENXIO;
                        goto out;

                case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
                        DEB2("NOT ACK received after data byte\n");
                        pca_stop(adap);
                        goto out;

                case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
                        DEB2("Arbitration lost\n");
                        /*
                         * The PCA9564 data sheet (2006-09-01) says "A
                         * START condition will be transmitted when the
                         * bus becomes free (STOP or SCL and SDA high)"
                         * when the STA bit is set (p. 11).
                         *
                         * In case this won't work, try pca_reset()
                         * instead.
                         */
                        pca_start(adap);
                        goto out;

                case 0x58: /* Data byte has been received; NOT ACK has been returned */
                        if (numbytes == msg->len - 1) {
                                pca_rx_byte(adap, &msg->buf[numbytes], 0);
                                curmsg++; numbytes = 0;
                                if (curmsg == num)
                                        pca_stop(adap);
                                else
                                        completed = pca_repeated_start(adap);
                        } else {
                                DEB2("NOT ACK sent after data byte received. "
                                     "Not final byte. numbytes %d. len %d\n",
                                     numbytes, msg->len);
                                pca_stop(adap);
                                goto out;
                        }
                        break;
                case 0x70: /* Bus error - SDA stuck low */
                        DEB2("BUS ERROR - SDA Stuck low\n");
                        pca_reset(adap);
                        goto out;
                case 0x90: /* Bus error - SCL stuck low */
                        DEB2("BUS ERROR - SCL Stuck low\n");
                        pca_reset(adap);
                        goto out;
                case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
                        DEB2("BUS ERROR - Illegal START or STOP\n");
                        pca_reset(adap);
                        goto out;
                default:
                        dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state);
                        break;
                }

                if (!completed)
                        goto out;
        }

        ret = curmsg;
 out:
        DEB1("}}} transferred %d/%d messages. "
             "status is %#04x. control is %#04x\n",
             curmsg, num, pca_status(adap),
             pca_get_con(adap));
        return ret;
}

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

static const struct i2c_algorithm pca_algo = {
        .master_xfer    = pca_xfer,
        .functionality  = pca_func,
};

static unsigned int pca_probe_chip(struct i2c_adapter *adap)
{
        struct i2c_algo_pca_data *pca_data = adap->algo_data;
        /* The trick here is to check if there is an indirect register
         * available. If there is one, we will read the value we first
         * wrote on I2C_PCA_IADR. Otherwise, we will read the last value
         * we wrote on I2C_PCA_ADR
         */
        pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
        pca_outw(pca_data, I2C_PCA_IND, 0xAA);
        pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ITO);
        pca_outw(pca_data, I2C_PCA_IND, 0x00);
        pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
        if (pca_inw(pca_data, I2C_PCA_IND) == 0xAA) {
                printk(KERN_INFO "%s: PCA9665 detected.\n", adap->name);
                pca_data->chip = I2C_PCA_CHIP_9665;
        } else {
                printk(KERN_INFO "%s: PCA9564 detected.\n", adap->name);
                pca_data->chip = I2C_PCA_CHIP_9564;
        }
        return pca_data->chip;
}

static int pca_init(struct i2c_adapter *adap)
{
        struct i2c_algo_pca_data *pca_data = adap->algo_data;

        adap->algo = &pca_algo;

        if (pca_probe_chip(adap) == I2C_PCA_CHIP_9564) {
                static int freqs[] = {330, 288, 217, 146, 88, 59, 44, 36};
                int clock;

                if (pca_data->i2c_clock > 7) {
                        switch (pca_data->i2c_clock) {
                        case 330000:
                                pca_data->i2c_clock = I2C_PCA_CON_330kHz;
                                break;
                        case 288000:
                                pca_data->i2c_clock = I2C_PCA_CON_288kHz;
                                break;
                        case 217000:
                                pca_data->i2c_clock = I2C_PCA_CON_217kHz;
                                break;
                        case 146000:
                                pca_data->i2c_clock = I2C_PCA_CON_146kHz;
                                break;
                        case 88000:
                                pca_data->i2c_clock = I2C_PCA_CON_88kHz;
                                break;
                        case 59000:
                                pca_data->i2c_clock = I2C_PCA_CON_59kHz;
                                break;
                        case 44000:
                                pca_data->i2c_clock = I2C_PCA_CON_44kHz;
                                break;
                        case 36000:
                                pca_data->i2c_clock = I2C_PCA_CON_36kHz;
                                break;
                        default:
                                printk(KERN_WARNING
                                        "%s: Invalid I2C clock speed selected."
                                        " Using default 59kHz.\n", adap->name);
                        pca_data->i2c_clock = I2C_PCA_CON_59kHz;
                        }
                } else {
                        printk(KERN_WARNING "%s: "
                                "Choosing the clock frequency based on "
                                "index is deprecated."
                                " Use the nominal frequency.\n", adap->name);
                }

                pca_reset(pca_data);

                clock = pca_clock(pca_data);
                printk(KERN_INFO "%s: Clock frequency is %dkHz\n",
                     adap->name, freqs[clock]);

                pca_set_con(pca_data, I2C_PCA_CON_ENSIO | clock);
        } else {
                int clock;
                int mode;
                int tlow, thi;
                /* Values can be found on PCA9665 datasheet section 7.3.2.6 */
                int min_tlow, min_thi;
                /* These values are the maximum raise and fall values allowed
                 * by the I2C operation mode (Standard, Fast or Fast+)
                 * They are used (added) below to calculate the clock dividers
                 * of PCA9665. Note that they are slightly different of the
                 * real maximum, to allow the change on mode exactly on the
                 * maximum clock rate for each mode
                 */
                int raise_fall_time;

                if (pca_data->i2c_clock > 1265800) {
                        printk(KERN_WARNING "%s: I2C clock speed too high."
                                " Using 1265.8kHz.\n", adap->name);
                        pca_data->i2c_clock = 1265800;
                }

                if (pca_data->i2c_clock < 60300) {
                        printk(KERN_WARNING "%s: I2C clock speed too low."
                                " Using 60.3kHz.\n", adap->name);
                        pca_data->i2c_clock = 60300;
                }

                /* To avoid integer overflow, use clock/100 for calculations */
                clock = pca_clock(pca_data) / 100;

                if (pca_data->i2c_clock > 1000000) {
                        mode = I2C_PCA_MODE_TURBO;
                        min_tlow = 14;
                        min_thi  = 5;
                        raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
                } else if (pca_data->i2c_clock > 400000) {
                        mode = I2C_PCA_MODE_FASTP;
                        min_tlow = 17;
                        min_thi  = 9;
                        raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
                } else if (pca_data->i2c_clock > 100000) {
                        mode = I2C_PCA_MODE_FAST;
                        min_tlow = 44;
                        min_thi  = 20;
                        raise_fall_time = 58; /* Raise 29e-8s, Fall 29e-8s */
                } else {
                        mode = I2C_PCA_MODE_STD;
                        min_tlow = 157;
                        min_thi  = 134;
                        raise_fall_time = 127; /* Raise 29e-8s, Fall 98e-8s */
                }

                /* The minimum clock that respects the thi/tlow = 134/157 is
                 * 64800 Hz. Below that, we have to fix the tlow to 255 and
                 * calculate the thi factor.
                 */
                if (clock < 648) {
                        tlow = 255;
                        thi = 1000000 - clock * raise_fall_time;
                        thi /= (I2C_PCA_OSC_PER * clock) - tlow;
                } else {
                        tlow = (1000000 - clock * raise_fall_time) * min_tlow;
                        tlow /= I2C_PCA_OSC_PER * clock * (min_thi + min_tlow);
                        thi = tlow * min_thi / min_tlow;
                }

                pca_reset(pca_data);

                printk(KERN_INFO
                     "%s: Clock frequency is %dHz\n", adap->name, clock * 100);

                pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IMODE);
                pca_outw(pca_data, I2C_PCA_IND, mode);
                pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLL);
                pca_outw(pca_data, I2C_PCA_IND, tlow);
                pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLH);
                pca_outw(pca_data, I2C_PCA_IND, thi);

                pca_set_con(pca_data, I2C_PCA_CON_ENSIO);
        }
        udelay(500); /* 500 us for oscillator to stabilise */

        return 0;
}

/*
 * registering functions to load algorithms at runtime
 */
int i2c_pca_add_bus(struct i2c_adapter *adap)
{
        int rval;

        rval = pca_init(adap);
        if (rval)
                return rval;

        return i2c_add_adapter(adap);
}
EXPORT_SYMBOL(i2c_pca_add_bus);

int i2c_pca_add_numbered_bus(struct i2c_adapter *adap)
{
        int rval;

        rval = pca_init(adap);
        if (rval)
                return rval;

        return i2c_add_numbered_adapter(adap);
}
EXPORT_SYMBOL(i2c_pca_add_numbered_bus);

MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>, "
        "Wolfram Sang <w.sang@pengutronix.de>");
MODULE_DESCRIPTION("I2C-Bus PCA9564/PCA9665 algorithm");
MODULE_LICENSE("GPL");

module_param(i2c_debug, int, 0);