/*
 * i2c-au1550.c: SMBus (i2c) adapter for Alchemy PSC interface
 * Copyright (C) 2004 Embedded Edge, LLC <dan@embeddededge.com>
 *
 * 2.6 port by Matt Porter <mporter@kernel.crashing.org>
 *
 * The documentation describes this as an SMBus controller, but it doesn't
 * understand any of the SMBus protocol in hardware.  It's really an I2C
 * controller that could emulate most of the SMBus in software.
 *
 * This is just a skeleton adapter to use with the Au1550 PSC
 * algorithm.  It was developed for the Pb1550, but will work with
 * any Au1550 board that has a similar PSC configuration.
 *
 * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/slab.h>

#include <asm/mach-au1x00/au1xxx.h>
#include <asm/mach-au1x00/au1xxx_psc.h>

struct i2c_au1550_data {
        u32     psc_base;
        int     xfer_timeout;
        int     ack_timeout;
        struct i2c_adapter adap;
        struct resource *ioarea;
};

static int
wait_xfer_done(struct i2c_au1550_data *adap)
{
        u32     stat;
        int     i;
        volatile psc_smb_t      *sp;

        sp = (volatile psc_smb_t *)(adap->psc_base);

        /* Wait for Tx Buffer Empty
        */
        for (i = 0; i < adap->xfer_timeout; i++) {
                stat = sp->psc_smbstat;
                au_sync();
                if ((stat & PSC_SMBSTAT_TE) != 0)
                        return 0;

                udelay(1);
        }

        return -ETIMEDOUT;
}

static int
wait_ack(struct i2c_au1550_data *adap)
{
        u32     stat;
        volatile psc_smb_t      *sp;

        if (wait_xfer_done(adap))
                return -ETIMEDOUT;

        sp = (volatile psc_smb_t *)(adap->psc_base);

        stat = sp->psc_smbevnt;
        au_sync();

        if ((stat & (PSC_SMBEVNT_DN | PSC_SMBEVNT_AN | PSC_SMBEVNT_AL)) != 0)
                return -ETIMEDOUT;

        return 0;
}

static int
wait_master_done(struct i2c_au1550_data *adap)
{
        u32     stat;
        int     i;
        volatile psc_smb_t      *sp;

        sp = (volatile psc_smb_t *)(adap->psc_base);

        /* Wait for Master Done.
        */
        for (i = 0; i < adap->xfer_timeout; i++) {
                stat = sp->psc_smbevnt;
                au_sync();
                if ((stat & PSC_SMBEVNT_MD) != 0)
                        return 0;
                udelay(1);
        }

        return -ETIMEDOUT;
}

static int
do_address(struct i2c_au1550_data *adap, unsigned int addr, int rd, int q)
{
        volatile psc_smb_t      *sp;
        u32                     stat;

        sp = (volatile psc_smb_t *)(adap->psc_base);

        /* Reset the FIFOs, clear events.
        */
        stat = sp->psc_smbstat;
        sp->psc_smbevnt = PSC_SMBEVNT_ALLCLR;
        au_sync();

        if (!(stat & PSC_SMBSTAT_TE) || !(stat & PSC_SMBSTAT_RE)) {
                sp->psc_smbpcr = PSC_SMBPCR_DC;
                au_sync();
                do {
                        stat = sp->psc_smbpcr;
                        au_sync();
                } while ((stat & PSC_SMBPCR_DC) != 0);
                udelay(50);
        }

        /* Write out the i2c chip address and specify operation
        */
        addr <<= 1;
        if (rd)
                addr |= 1;

        /* zero-byte xfers stop immediately */
        if (q)
                addr |= PSC_SMBTXRX_STP;

        /* Put byte into fifo, start up master.
        */
        sp->psc_smbtxrx = addr;
        au_sync();
        sp->psc_smbpcr = PSC_SMBPCR_MS;
        au_sync();
        if (wait_ack(adap))
                return -EIO;
        return (q) ? wait_master_done(adap) : 0;
}

static u32
wait_for_rx_byte(struct i2c_au1550_data *adap, u32 *ret_data)
{
        int     j;
        u32     data, stat;
        volatile psc_smb_t      *sp;

        if (wait_xfer_done(adap))
                return -EIO;

        sp = (volatile psc_smb_t *)(adap->psc_base);

        j =  adap->xfer_timeout * 100;
        do {
                j--;
                if (j <= 0)
                        return -EIO;

                stat = sp->psc_smbstat;
                au_sync();
                if ((stat & PSC_SMBSTAT_RE) == 0)
                        j = 0;
                else
                        udelay(1);
        } while (j > 0);
        data = sp->psc_smbtxrx;
        au_sync();
        *ret_data = data;

        return 0;
}

static int
i2c_read(struct i2c_au1550_data *adap, unsigned char *buf,
                    unsigned int len)
{
        int     i;
        u32     data;
        volatile psc_smb_t      *sp;

        if (len == 0)
                return 0;

        /* A read is performed by stuffing the transmit fifo with
         * zero bytes for timing, waiting for bytes to appear in the
         * receive fifo, then reading the bytes.
         */

        sp = (volatile psc_smb_t *)(adap->psc_base);

        i = 0;
        while (i < (len-1)) {
                sp->psc_smbtxrx = 0;
                au_sync();
                if (wait_for_rx_byte(adap, &data))
                        return -EIO;

                buf[i] = data;
                i++;
        }

        /* The last byte has to indicate transfer done.
        */
        sp->psc_smbtxrx = PSC_SMBTXRX_STP;
        au_sync();
        if (wait_master_done(adap))
                return -EIO;

        data = sp->psc_smbtxrx;
        au_sync();
        buf[i] = data;
        return 0;
}

static int
i2c_write(struct i2c_au1550_data *adap, unsigned char *buf,
                     unsigned int len)
{
        int     i;
        u32     data;
        volatile psc_smb_t      *sp;

        if (len == 0)
                return 0;

        sp = (volatile psc_smb_t *)(adap->psc_base);

        i = 0;
        while (i < (len-1)) {
                data = buf[i];
                sp->psc_smbtxrx = data;
                au_sync();
                if (wait_ack(adap))
                        return -EIO;
                i++;
        }

        /* The last byte has to indicate transfer done.
        */
        data = buf[i];
        data |= PSC_SMBTXRX_STP;
        sp->psc_smbtxrx = data;
        au_sync();
        if (wait_master_done(adap))
                return -EIO;
        return 0;
}

static int
au1550_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs, int num)
{
        struct i2c_au1550_data *adap = i2c_adap->algo_data;
        volatile psc_smb_t *sp = (volatile psc_smb_t *)adap->psc_base;
        struct i2c_msg *p;
        int i, err = 0;

        sp->psc_ctrl = PSC_CTRL_ENABLE;
        au_sync();

        for (i = 0; !err && i < num; i++) {
                p = &msgs[i];
                err = do_address(adap, p->addr, p->flags & I2C_M_RD,
                                 (p->len == 0));
                if (err || !p->len)
                        continue;
                if (p->flags & I2C_M_RD)
                        err = i2c_read(adap, p->buf, p->len);
                else
                        err = i2c_write(adap, p->buf, p->len);
        }

        /* Return the number of messages processed, or the error code.
        */
        if (err == 0)
                err = num;

        sp->psc_ctrl = PSC_CTRL_SUSPEND;
        au_sync();

        return err;
}

static u32
au1550_func(struct i2c_adapter *adap)
{
        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}

static const struct i2c_algorithm au1550_algo = {
        .master_xfer    = au1550_xfer,
        .functionality  = au1550_func,
};

static void i2c_au1550_setup(struct i2c_au1550_data *priv)
{
        volatile psc_smb_t *sp = (volatile psc_smb_t *)priv->psc_base;
        u32 stat;

        sp->psc_ctrl = PSC_CTRL_DISABLE;
        au_sync();
        sp->psc_sel = PSC_SEL_PS_SMBUSMODE;
        sp->psc_smbcfg = 0;
        au_sync();
        sp->psc_ctrl = PSC_CTRL_ENABLE;
        au_sync();
        do {
                stat = sp->psc_smbstat;
                au_sync();
        } while ((stat & PSC_SMBSTAT_SR) == 0);

        sp->psc_smbcfg = (PSC_SMBCFG_RT_FIFO8 | PSC_SMBCFG_TT_FIFO8 |
                                PSC_SMBCFG_DD_DISABLE);

        /* Divide by 8 to get a 6.25 MHz clock.  The later protocol
         * timings are based on this clock.
         */
        sp->psc_smbcfg |= PSC_SMBCFG_SET_DIV(PSC_SMBCFG_DIV8);
        sp->psc_smbmsk = PSC_SMBMSK_ALLMASK;
        au_sync();

        /* Set the protocol timer values.  See Table 71 in the
         * Au1550 Data Book for standard timing values.
         */
        sp->psc_smbtmr = PSC_SMBTMR_SET_TH(0) | PSC_SMBTMR_SET_PS(15) | \
                PSC_SMBTMR_SET_PU(15) | PSC_SMBTMR_SET_SH(15) | \
                PSC_SMBTMR_SET_SU(15) | PSC_SMBTMR_SET_CL(15) | \
                PSC_SMBTMR_SET_CH(15);
        au_sync();

        sp->psc_smbcfg |= PSC_SMBCFG_DE_ENABLE;
        do {
                stat = sp->psc_smbstat;
                au_sync();
        } while ((stat & PSC_SMBSTAT_SR) == 0);

        sp->psc_ctrl = PSC_CTRL_SUSPEND;
        au_sync();
}

static void i2c_au1550_disable(struct i2c_au1550_data *priv)
{
        volatile psc_smb_t *sp = (volatile psc_smb_t *)priv->psc_base;

        sp->psc_smbcfg = 0;
        sp->psc_ctrl = PSC_CTRL_DISABLE;
        au_sync();
}

/*
 * registering functions to load algorithms at runtime
 * Prior to calling us, the 50MHz clock frequency and routing
 * must have been set up for the PSC indicated by the adapter.
 */
static int __devinit
i2c_au1550_probe(struct platform_device *pdev)
{
        struct i2c_au1550_data *priv;
        struct resource *r;
        int ret;

        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!r) {
                ret = -ENODEV;
                goto out;
        }

        priv = kzalloc(sizeof(struct i2c_au1550_data), GFP_KERNEL);
        if (!priv) {
                ret = -ENOMEM;
                goto out;
        }

        priv->ioarea = request_mem_region(r->start, r->end - r->start + 1,
                                          pdev->name);
        if (!priv->ioarea) {
                ret = -EBUSY;
                goto out_mem;
        }

        priv->psc_base = CKSEG1ADDR(r->start);
        priv->xfer_timeout = 200;
        priv->ack_timeout = 200;

        priv->adap.id = I2C_HW_AU1550_PSC;
        priv->adap.nr = pdev->id;
        priv->adap.algo = &au1550_algo;
        priv->adap.algo_data = priv;
        priv->adap.dev.parent = &pdev->dev;
        strlcpy(priv->adap.name, "Au1xxx PSC I2C", sizeof(priv->adap.name));

        /* Now, set up the PSC for SMBus PIO mode.
        */
        i2c_au1550_setup(priv);

        ret = i2c_add_numbered_adapter(&priv->adap);
        if (ret == 0) {
                platform_set_drvdata(pdev, priv);
                return 0;
        }

        i2c_au1550_disable(priv);

        release_resource(priv->ioarea);
        kfree(priv->ioarea);
out_mem:
        kfree(priv);
out:
        return ret;
}

static int __devexit
i2c_au1550_remove(struct platform_device *pdev)
{
        struct i2c_au1550_data *priv = platform_get_drvdata(pdev);

        platform_set_drvdata(pdev, NULL);
        i2c_del_adapter(&priv->adap);
        i2c_au1550_disable(priv);
        release_resource(priv->ioarea);
        kfree(priv->ioarea);
        kfree(priv);
        return 0;
}

#ifdef CONFIG_PM
static int
i2c_au1550_suspend(struct platform_device *pdev, pm_message_t state)
{
        struct i2c_au1550_data *priv = platform_get_drvdata(pdev);

        i2c_au1550_disable(priv);

        return 0;
}

static int
i2c_au1550_resume(struct platform_device *pdev)
{
        struct i2c_au1550_data *priv = platform_get_drvdata(pdev);

        i2c_au1550_setup(priv);

        return 0;
}
#else
#define i2c_au1550_suspend      NULL
#define i2c_au1550_resume       NULL
#endif

static struct platform_driver au1xpsc_smbus_driver = {
        .driver = {
                .name   = "au1xpsc_smbus",
                .owner  = THIS_MODULE,
        },
        .probe          = i2c_au1550_probe,
        .remove         = __devexit_p(i2c_au1550_remove),
        .suspend        = i2c_au1550_suspend,
        .resume         = i2c_au1550_resume,
};

static int __init
i2c_au1550_init(void)
{
        return platform_driver_register(&au1xpsc_smbus_driver);
}

static void __exit
i2c_au1550_exit(void)
{
        platform_driver_unregister(&au1xpsc_smbus_driver);
}

MODULE_AUTHOR("Dan Malek, Embedded Edge, LLC.");
MODULE_DESCRIPTION("SMBus adapter Alchemy pb1550");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:au1xpsc_smbus");

module_init (i2c_au1550_init);
module_exit (i2c_au1550_exit);