i2c-algo-pca.c

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/*
 *  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.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 *  MA 02110-1301 USA.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/delay.h>
#include <linux/jiffies.h>
#include <linux/init.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 oscilator 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 <[email protected]>, "
    "Wolfram Sang <[email protected]>");
MODULE_DESCRIPTION("I2C-Bus PCA9564/PCA9665 algorithm");
MODULE_LICENSE("GPL");

module_param(i2c_debug, int, 0);