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/*

 * drivers/i2c/i2c-ibm_iic.c

 *

 * Support for the IIC peripheral on IBM PPC 4xx

 *

 * Copyright (c) 2003 Zultys Technologies.

 * Eugene Surovegin <eugene.surovegin@zultys.com> or <ebs@ebshome.net>

 *

 * Based on original work by

 *      Ian DaSilva  <idasilva@mvista.com>

 *      Armin Kuster <akuster@mvista.com>

 *      Matt Porter  <mporter@mvista.com>

 *

 *      Copyright 2000-2003 MontaVista Software Inc.

 *

 * Original driver version was highly leveraged from i2c-elektor.c

 *

 *      Copyright 1995-97 Simon G. Vogl

 *                1998-99 Hans Berglund

 *

 *      With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>

 *      and even Frodo Looijaard <frodol@dds.nl>

 *

 * 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.

 *

 */

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/ioport.h>

#include <linux/delay.h>

#include <linux/slab.h>

#include <linux/init.h>

#include <linux/interrupt.h>

#include <asm/irq.h>

#include <asm/io.h>

#include <linux/i2c.h>

#include <linux/i2c-id.h>

#include <asm/ocp.h>

#include <asm/ibm4xx.h>

#include "i2c-ibm_iic.h"

#define DRIVER_VERSION "2.0"

MODULE_DESCRIPTION("IBM IIC driver v" DRIVER_VERSION);

MODULE_LICENSE("GPL");

static int iic_scan = 0;

MODULE_PARM(iic_scan, "i");

MODULE_PARM_DESC(iic_scan, "Scan for active chips on the bus");

static int iic_force_poll = 0;

MODULE_PARM(iic_force_poll, "i");

MODULE_PARM_DESC(iic_force_poll, "Force polling mode");

static int iic_force_fast = 0;

MODULE_PARM(iic_force_fast, "i");

MODULE_PARM_DESC(iic_fast_poll, "Force fast mode (400 kHz)");

#define DBG_LEVEL 0

#ifdef DBG

#undef DBG

#endif

#ifdef DBG2

#undef DBG2

#endif

#if DBG_LEVEL > 0

#  define DBG(x...)     printk(KERN_DEBUG "ibm-iic" ##x)

#else

#  define DBG(x...)     ((void)0)

#endif

#if DBG_LEVEL > 1

#  define DBG2(x...)    DBG( ##x )

#else

#  define DBG2(x...)    ((void)0)

#endif

#if DBG_LEVEL > 2

static void dump_iic_regs(const char* header, struct ibm_iic_private* dev)

{

        volatile struct iic_regs *iic = dev->vaddr;

        printk(KERN_DEBUG "ibm-iic%d: %s\n", dev->idx, header);

        printk(KERN_DEBUG "  cntl     = 0x%02x, mdcntl = 0x%02x\n"

               KERN_DEBUG "  sts      = 0x%02x, extsts = 0x%02x\n"

               KERN_DEBUG "  clkdiv   = 0x%02x, xfrcnt = 0x%02x\n"

               KERN_DEBUG "  xtcntlss = 0x%02x, directcntl = 0x%02x\n",

                in_8(&iic->cntl), in_8(&iic->mdcntl), in_8(&iic->sts),

                in_8(&iic->extsts), in_8(&iic->clkdiv), in_8(&iic->xfrcnt),

                in_8(&iic->xtcntlss), in_8(&iic->directcntl));

}

#  define DUMP_REGS(h,dev)      dump_iic_regs((h),(dev))

#else

#  define DUMP_REGS(h,dev)      ((void)0)

#endif

/* Enable/disable interrupt generation */

static inline void iic_interrupt_mode(struct ibm_iic_private* dev, int enable)

{

        out_8(&dev->vaddr->intmsk, enable ? INTRMSK_EIMTC : 0);

}

/*

 * Initialize IIC interface.

 */

static void iic_dev_init(struct ibm_iic_private* dev)

{

        volatile struct iic_regs *iic = dev->vaddr;

        DBG("%d: init\n", dev->idx);

        /* Clear master address */

        out_8(&iic->lmadr, 0);

        out_8(&iic->hmadr, 0);

        /* Clear slave address */

        out_8(&iic->lsadr, 0);

        out_8(&iic->hsadr, 0);

        /* Clear status & extended status */

        out_8(&iic->sts, STS_SCMP | STS_IRQA);

        out_8(&iic->extsts, EXTSTS_IRQP | EXTSTS_IRQD | EXTSTS_LA

                            | EXTSTS_ICT | EXTSTS_XFRA);

        /* Set clock divider */

        out_8(&iic->clkdiv, dev->clckdiv);

        /* Clear transfer count */

        out_8(&iic->xfrcnt, 0);

        /* Clear extended control and status */

        out_8(&iic->xtcntlss, XTCNTLSS_SRC | XTCNTLSS_SRS | XTCNTLSS_SWC

                            | XTCNTLSS_SWS);

        /* Clear control register */

        out_8(&iic->cntl, 0);

        /* Enable interrupts if possible */

        iic_interrupt_mode(dev, dev->irq >= 0);

        /* Set mode control */

        out_8(&iic->mdcntl, MDCNTL_FMDB | MDCNTL_EINT | MDCNTL_EUBS

                            | (dev->fast_mode ? MDCNTL_FSM : 0));

        DUMP_REGS("iic_init", dev);

}

/*

 * Reset IIC interface

 */

static void iic_dev_reset(struct ibm_iic_private* dev)

{

        volatile struct iic_regs *iic = dev->vaddr;

        int i;

        u8 dc;

        DBG("%d: soft reset\n", dev->idx);

        DUMP_REGS("reset", dev);

        /* Place chip in the reset state */

        out_8(&iic->xtcntlss, XTCNTLSS_SRST);

        /* Check if bus is free */

        dc = in_8(&iic->directcntl);   

        if (!DIRCTNL_FREE(dc)){

                DBG("%d: trying to regain bus control\n", dev->idx);

                /* Try to set bus free state */

                out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);   

                /* Wait until we regain bus control */

                for (i = 0; i < 100; ++i){

                        dc = in_8(&iic->directcntl);

                        if (DIRCTNL_FREE(dc))

                                break;

                        /* Toggle SCL line */

                        dc ^= DIRCNTL_SCC;

                        out_8(&iic->directcntl, dc);

                        udelay(10);

                        dc ^= DIRCNTL_SCC;

                        out_8(&iic->directcntl, dc);

                        /* be nice */

                        cond_resched();

                }

        }

        /* Remove reset */

        out_8(&iic->xtcntlss, 0);

        /* Reinitialize interface */

        iic_dev_init(dev);

}

/*

 * IIC interrupt handler

 */

static irqreturn_t iic_handler(int irq, void *dev_id, struct pt_regs *regs)

{

        struct ibm_iic_private* dev = (struct ibm_iic_private*)dev_id;

        volatile struct iic_regs* iic = dev->vaddr;

        DBG2("%d: irq handler, STS = 0x%02x, EXTSTS = 0x%02x\n",

             dev->idx, in_8(&iic->sts), in_8(&iic->extsts));

        /* Acknowledge IRQ and wakeup iic_wait_for_tc */

        out_8(&iic->sts, STS_IRQA | STS_SCMP);

        wake_up_interruptible(&dev->wq);

        return IRQ_HANDLED;

}

/*

 * Get master transfer result and clear errors if any.

 * Returns the number of actually transferred bytes or error (<0)

 */

static int iic_xfer_result(struct ibm_iic_private* dev)

{

        volatile struct iic_regs *iic = dev->vaddr;    

        if (unlikely(in_8(&iic->sts) & STS_ERR)){

                DBG("%d: xfer error, EXTSTS = 0x%02x\n", dev->idx,

                        in_8(&iic->extsts));

                /* Clear errors and possible pending IRQs */

                out_8(&iic->extsts, EXTSTS_IRQP | EXTSTS_IRQD |

                        EXTSTS_LA | EXTSTS_ICT | EXTSTS_XFRA);

                /* Flush master data buffer */

                out_8(&iic->mdcntl, in_8(&iic->mdcntl) | MDCNTL_FMDB);

                /* Is bus free?

                 * If error happened during combined xfer

                 * IIC interface is usually stuck in some strange

                 * state, the only way out - soft reset.

                 */

                if ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){

                        DBG("%d: bus is stuck, resetting\n", dev->idx);

                        iic_dev_reset(dev);

                }

                return -EREMOTEIO;

        }

        else

                return in_8(&iic->xfrcnt) & XFRCNT_MTC_MASK;

}

/*

 * Try to abort active transfer.

 */

static void iic_abort_xfer(struct ibm_iic_private* dev)

{

        volatile struct iic_regs *iic = dev->vaddr;

        unsigned long x;

        DBG("%d: iic_abort_xfer\n", dev->idx);

        out_8(&iic->cntl, CNTL_HMT);

        /*

         * Wait for the abort command to complete.

         * It's not worth to be optimized, just poll (timeout >= 1 tick)

         */

        x = jiffies + 2;

        while ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){

                if (time_after(jiffies, x)){

                        DBG("%d: abort timeout, resetting...\n", dev->idx);

                        iic_dev_reset(dev);

                        return;

                }

                schedule();

        }

        /* Just to clear errors */

        iic_xfer_result(dev);

}

/*

 * Wait for master transfer to complete.

 * It puts current process to sleep until we get interrupt or timeout expires.

 * Returns the number of transferred bytes or error (<0)

 */

static int iic_wait_for_tc(struct ibm_iic_private* dev){

        volatile struct iic_regs *iic = dev->vaddr;

        int ret = 0;

        if (dev->irq >= 0){

                /* Interrupt mode */

                wait_queue_t wait;

                init_waitqueue_entry(&wait, current);

                add_wait_queue(&dev->wq, &wait);

                set_current_state(TASK_INTERRUPTIBLE);

                if (in_8(&iic->sts) & STS_PT)

                        schedule_timeout(dev->adap.timeout * HZ);

                set_current_state(TASK_RUNNING);

                remove_wait_queue(&dev->wq, &wait);

                if (unlikely(signal_pending(current))){

                        DBG("%d: wait interrupted\n", dev->idx);

                        ret = -ERESTARTSYS;

                } else if (unlikely(in_8(&iic->sts) & STS_PT)){

                        DBG("%d: wait timeout\n", dev->idx);

                        ret = -ETIMEDOUT;

                }

        }

        else {

                /* Polling mode */

                unsigned long x = jiffies + dev->adap.timeout * HZ;

                while (in_8(&iic->sts) & STS_PT){

                        if (unlikely(time_after(jiffies, x))){

                                DBG("%d: poll timeout\n", dev->idx);

                                ret = -ETIMEDOUT;

                                break;

                        }

                        if (unlikely(signal_pending(current))){

                                DBG("%d: poll interrupted\n", dev->idx);

                                ret = -ERESTARTSYS;

                                break;

                        }

                        schedule();

                }      

        }

        if (unlikely(ret < 0))

                iic_abort_xfer(dev);

        else

                ret = iic_xfer_result(dev);

        DBG2("%d: iic_wait_for_tc -> %d\n", dev->idx, ret);

        return ret;

}

/*

 * Low level master transfer routine

 */

static int iic_xfer_bytes(struct ibm_iic_private* dev, struct i2c_msg* pm,

                          int combined_xfer)

{

        volatile struct iic_regs *iic = dev->vaddr;

        char* buf = pm->buf;

        int i, j, loops, ret = 0;

        int len = pm->len;

        u8 cntl = (in_8(&iic->cntl) & CNTL_AMD) | CNTL_PT;

        if (pm->flags & I2C_M_RD)

                cntl |= CNTL_RW;

        loops = (len + 3) / 4;

        for (i = 0; i < loops; ++i, len -= 4){

                int count = len > 4 ? 4 : len;

                u8 cmd = cntl | ((count - 1) << CNTL_TCT_SHIFT);

                if (!(cntl & CNTL_RW))

                        for (j = 0; j < count; ++j)

                                out_8((volatile u8*)&iic->mdbuf, *buf++);

                if (i < loops - 1)

                        cmd |= CNTL_CHT;

                else if (combined_xfer)

                        cmd |= CNTL_RPST;

                DBG2("%d: xfer_bytes, %d, CNTL = 0x%02x\n", dev->idx, count, cmd);

                /* Start transfer */

                out_8(&iic->cntl, cmd);

                /* Wait for completion */

                ret = iic_wait_for_tc(dev);

                if (unlikely(ret < 0))

                        break;

                else if (unlikely(ret != count)){

                        DBG("%d: xfer_bytes, requested %d, transfered %d\n",

                                dev->idx, count, ret);

                        /* If it's not a last part of xfer, abort it */

                        if (combined_xfer || (i < loops - 1))

                                iic_abort_xfer(dev);

                        ret = -EREMOTEIO;

                        break;                         

                }

                if (cntl & CNTL_RW)

                        for (j = 0; j < count; ++j)

                                *buf++ = in_8((volatile u8*)&iic->mdbuf);

        }

        return ret > 0 ? 0 : ret;

}

/*

 * Set target slave address for master transfer

 */

static inline void iic_address(struct ibm_iic_private* dev, struct i2c_msg* msg)

{

        volatile struct iic_regs *iic = dev->vaddr;

        u16 addr = msg->addr;

        DBG2("%d: iic_address, 0x%03x (%d-bit)\n", dev->idx,

                addr, msg->flags & I2C_M_TEN ? 10 : 7);

        if (msg->flags & I2C_M_TEN){

            out_8(&iic->cntl, CNTL_AMD);

            out_8(&iic->lmadr, addr);

            out_8(&iic->hmadr, 0xf0 | ((addr >> 7) & 0x06));

        }

        else {

            out_8(&iic->cntl, 0);

            out_8(&iic->lmadr, addr << 1);

        }

}

static inline int iic_invalid_address(const struct i2c_msg* p)

{

        return (p->addr > 0x3ff) || (!(p->flags & I2C_M_TEN) && (p->addr > 0x7f));

}

static inline int iic_address_neq(const struct i2c_msg* p1,

                                  const struct i2c_msg* p2)

{

        return (p1->addr != p2->addr)

                || ((p1->flags & I2C_M_TEN) != (p2->flags & I2C_M_TEN));

}

/*

 * Generic master transfer entrypoint.

 * Returns the number of processed messages or error (<0)

 */

static int iic_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)

{

        struct ibm_iic_private* dev = (struct ibm_iic_private*)(i2c_get_adapdata(adap));

        volatile struct iic_regs *iic = dev->vaddr;

        int i, ret = 0;

        DBG2("%d: iic_xfer, %d msg(s)\n", dev->idx, num);

        if (!num)

                return 0;

        /* Check the sanity of the passed messages.

         * Uhh, generic i2c layer is more suitable place for such code...

         */

        if (unlikely(iic_invalid_address(&msgs[0]))){

                DBG("%d: invalid address 0x%03x (%d-bit)\n", dev->idx,

                        msgs[0].addr, msgs[0].flags & I2C_M_TEN ? 10 : 7);

                return -EINVAL;

        }              

        for (i = 0; i < num; ++i){

                if (unlikely(msgs[i].len <= 0)){

                        DBG("%d: invalid len %d in msg[%d]\n", dev->idx,

                                msgs[i].len, i);

                        return -EINVAL;

                }

                if (unlikely(iic_address_neq(&msgs[0], &msgs[i]))){

                        DBG("%d: invalid addr in msg[%d]\n", dev->idx, i);

                        return -EINVAL;

                }

        }

        /* Check bus state */

        if (unlikely((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE)){

                DBG("%d: iic_xfer, bus is not free\n", dev->idx);

                /* Usually it means something serious has happend.

                 * We *cannot* have unfinished previous transfer

                 * so it doesn't make any sense to try to stop it.

                 * Probably we were not able to recover from the

                 * previous error.

                 * The only *reasonable* thing I can think of here

                 * is soft reset.  --ebs

                 */

                iic_dev_reset(dev);

                if ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){

                        DBG("%d: iic_xfer, bus is still not free\n", dev->idx);

                        return -EREMOTEIO;

                }

        }

        else {

                /* Flush master data buffer (just in case) */

                out_8(&iic->mdcntl, in_8(&iic->mdcntl) | MDCNTL_FMDB);

        }

        /* Load slave address */

        iic_address(dev, &msgs[0]);

        /* Do real transfer */

        for (i = 0; i < num && !ret; ++i)

                ret = iic_xfer_bytes(dev, &msgs[i], i < num - 1);

        return ret < 0 ? ret : num;

}

static u32 iic_func(struct i2c_adapter *adap)

{

        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR;

}

static struct i2c_algorithm iic_algo = {

        .name           = "IBM IIC algorithm",

        .id             = I2C_ALGO_OCP,

        .master_xfer    = iic_xfer,

        .smbus_xfer     = NULL,

        .slave_send     = NULL,

        .slave_recv     = NULL,

        .algo_control   = NULL,

        .functionality  = iic_func

};

/*

 * Scan bus for valid 7-bit addresses (ie things that ACK on 1 byte read)

 * We only scan range [0x08 - 0x77], all other addresses are reserved anyway

 */

static void __devinit iic_scan_bus(struct ibm_iic_private* dev)

{

        int found = 0;

        char dummy;

        struct i2c_msg msg = {

                .buf   = &dummy,

                .len   = sizeof(dummy),

                .flags = I2C_M_RD

        };

        printk(KERN_INFO "ibm-iic%d: scanning bus...\n" KERN_INFO, dev->idx);

        for (msg.addr = 8; msg.addr < 0x78; ++msg.addr)

                if (iic_xfer(&dev->adap, &msg, 1) == 1){

                        ++found;

                        printk(" 0x%02x", msg.addr);

                }

        printk("%sibm-iic%d: %d device(s) detected\n",

                found ? "\n" KERN_INFO : "", dev->idx, found);

}

/*

 * Calculates IICx_CLCKDIV value for a specific OPB clock frequency

 */

static inline u8 iic_clckdiv(unsigned int opb)

{

        /* Compatibility kludge, should go away after all cards

         * are fixed to fill correct value for opbfreq.

         * Previous driver version used hardcoded divider value 4,

         * it corresponds to OPB frequency from the range (40, 50] MHz

         */

        if (!opb){

                printk(KERN_WARNING "ibm-iic: using compatibility value for OPB freq,"

                        " fix your board specific setup\n");

                opb = 50000000;

        }

        /* Convert to MHz */

        opb /= 1000000;

        if (opb < 20 || opb > 150){

                printk(KERN_CRIT "ibm-iic: invalid OPB clock frequency %u MHz\n",

                        opb);

                opb = opb < 20 ? 20 : 150;

        }

        return (u8)((opb + 9) / 10 - 1);

}

/*

 * Register single IIC interface

 */

static int __devinit iic_probe(struct ocp_device *ocp){

        struct ibm_iic_private* dev;

        struct i2c_adapter* adap;

        int ret;

        bd_t* bd = (bd_t*)&__res;

        if (!(dev = kmalloc(sizeof(*dev), GFP_KERNEL))){

                printk(KERN_CRIT "ibm-iic: failed to allocate device data\n");

                return -ENOMEM;

        }

        memset(dev, 0, sizeof(*dev));

        dev->idx = ocp->num;

        ocp_set_drvdata(ocp, dev);

        if (!(dev->vaddr = ioremap(ocp->paddr, sizeof(struct iic_regs)))){

                printk(KERN_CRIT "ibm-iic%d: failed to ioremap device registers\n",

                        dev->idx);

                ret = -ENXIO;

                goto fail2;

        }

        init_waitqueue_head(&dev->wq);

        dev->irq = iic_force_poll ? -1 : ocp->irq;

        if (dev->irq >= 0){

                /* Disable interrupts until we finish intialization,

                   assumes level-sensitive IRQ setup...

                 */

                iic_interrupt_mode(dev, 0);

                if (request_irq(dev->irq, iic_handler, 0, "IBM IIC", dev)){

                        printk(KERN_ERR "ibm-iic%d: request_irq %d failed\n",

                                dev->idx, dev->irq);

                        /* Fallback to the polling mode */     

                        dev->irq = -1;

                }

        }

        if (dev->irq < 0)

                printk(KERN_WARNING "ibm-iic%d: using polling mode\n",

                        dev->idx);

        /* Board specific settings */

        BUG_ON(dev->idx >= sizeof(bd->bi_iic_fast) / sizeof(bd->bi_iic_fast[0]));

        dev->fast_mode = iic_force_fast ? 1 : bd->bi_iic_fast[dev->idx];

        /* clckdiv is the same for *all* IIC interfaces,

         * but I'd rather make a copy than introduce another global. --ebs

         */

        dev->clckdiv = iic_clckdiv(bd->bi_opb_busfreq);

        DBG("%d: clckdiv = %d\n", dev->idx, dev->clckdiv);

        /* Initialize IIC interface */

        iic_dev_init(dev);

        /* Register it with i2c layer */

        adap = &dev->adap;

        strcpy(adap->dev.name, "IBM IIC");

        i2c_set_adapdata(adap, dev);

        adap->id = I2C_HW_OCP | iic_algo.id;

        adap->algo = &iic_algo;

        adap->client_register = NULL;

        adap->client_unregister = NULL;

        adap->timeout = 1;

        adap->retries = 1;

        if ((ret = i2c_add_adapter(adap)) != 0){

                printk(KERN_CRIT "ibm-iic%d: failed to register i2c adapter\n",

                        dev->idx);

                goto fail;

        }

        printk(KERN_INFO "ibm-iic%d: using %s mode\n", dev->idx,

                dev->fast_mode ? "fast (400 kHz)" : "standard (100 kHz)");

        /* Scan bus if requested by user */

        if (iic_scan)

                iic_scan_bus(dev);

        return 0;

fail:  

        if (dev->irq >= 0){

                iic_interrupt_mode(dev, 0);

                free_irq(dev->irq, dev);

        }      

        iounmap((void*)dev->vaddr);

fail2: 

        ocp_set_drvdata(ocp, 0);

        kfree(dev);    

        return ret;

}

/*

 * Cleanup initialized IIC interface

 */

static void __devexit iic_remove(struct ocp_device *ocp)

{

        struct ibm_iic_private* dev = (struct ibm_iic_private*)ocp_get_drvdata(ocp);

        BUG_ON(dev == NULL);

        if (i2c_del_adapter(&dev->adap)){

                printk(KERN_CRIT "ibm-iic%d: failed to delete i2c adapter :(\n",

                        dev->idx);

                /* That's *very* bad, just shutdown IRQ ... */

                if (dev->irq >= 0){

                    iic_interrupt_mode(dev, 0);

                    free_irq(dev->irq, dev);

                    dev->irq = -1;

                }

        } else {

                if (dev->irq >= 0){

                    iic_interrupt_mode(dev, 0);

                    free_irq(dev->irq, dev);

                }

                iounmap((void*)dev->vaddr);

                kfree(dev);

        }

}

static struct ocp_device_id ibm_iic_ids[] __devinitdata =

{

        { .vendor = OCP_VENDOR_IBM, .device = OCP_FUNC_IIC },

        { .vendor = OCP_VENDOR_INVALID }

};

MODULE_DEVICE_TABLE(ocp, ibm_iic_ids);

static struct ocp_driver ibm_iic_driver =

{

        .name           = "ocp_iic",

        .id_table       = ibm_iic_ids,

        .probe          = iic_probe,

        .remove         = __devexit_p(iic_remove),

#if defined(CONFIG_PM)

        .suspend        = NULL,

        .resume         = NULL,

#endif

};

static int __init iic_init(void)

{

        printk(KERN_INFO "IBM IIC driver v" DRIVER_VERSION "\n");

        return ocp_module_init(&ibm_iic_driver);

}

static void __exit iic_exit(void)

{

        ocp_unregister_driver(&ibm_iic_driver);

}

module_init(iic_init);

module_exit(iic_exit);