bbc_i2c.c

Go to the documentation of this file.

/* bbc_i2c.c: I2C low-level driver for BBC device on UltraSPARC-III
 *            platforms.
 *
 * Copyright (C) 2001, 2008 David S. Miller ([email protected])
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <asm/bbc.h>
#include <asm/io.h>

#include "bbc_i2c.h"

/* Convert this driver to use i2c bus layer someday... */
#define I2C_PCF_PIN 0x80
#define I2C_PCF_ESO 0x40
#define I2C_PCF_ES1 0x20
#define I2C_PCF_ES2 0x10
#define I2C_PCF_ENI 0x08
#define I2C_PCF_STA 0x04
#define I2C_PCF_STO 0x02
#define I2C_PCF_ACK 0x01

#define I2C_PCF_START    (I2C_PCF_PIN | I2C_PCF_ESO | I2C_PCF_ENI | I2C_PCF_STA | I2C_PCF_ACK)
#define I2C_PCF_STOP     (I2C_PCF_PIN | I2C_PCF_ESO | I2C_PCF_STO | I2C_PCF_ACK)
#define I2C_PCF_REPSTART (              I2C_PCF_ESO | I2C_PCF_STA | I2C_PCF_ACK)
#define I2C_PCF_IDLE     (I2C_PCF_PIN | I2C_PCF_ESO               | I2C_PCF_ACK)

#define I2C_PCF_INI 0x40   /* 1 if not initialized */
#define I2C_PCF_STS 0x20
#define I2C_PCF_BER 0x10
#define I2C_PCF_AD0 0x08
#define I2C_PCF_LRB 0x08
#define I2C_PCF_AAS 0x04
#define I2C_PCF_LAB 0x02
#define I2C_PCF_BB  0x01

/* The BBC devices have two I2C controllers.  The first I2C controller
 * connects mainly to configuration proms (NVRAM, cpu configuration,
 * dimm types, etc.).  Whereas the second I2C controller connects to
 * environmental control devices such as fans and temperature sensors.
 * The second controller also connects to the smartcard reader, if present.
 */

static void set_device_claimage(struct bbc_i2c_bus *bp, struct platform_device *op, int val)
{
    int i;

    for (i = 0; i < NUM_CHILDREN; i++) {
        if (bp->devs[i].device == op) {
            bp->devs[i].client_claimed = val;
            return;
        }
    }
}

#define claim_device(BP,ECHILD)     set_device_claimage(BP,ECHILD,1)
#define release_device(BP,ECHILD)   set_device_claimage(BP,ECHILD,0)

struct platform_device *bbc_i2c_getdev(struct bbc_i2c_bus *bp, int index)
{
    struct platform_device *op = NULL;
    int curidx = 0, i;

    for (i = 0; i < NUM_CHILDREN; i++) {
        if (!(op = bp->devs[i].device))
            break;
        if (curidx == index)
            goto out;
        op = NULL;
        curidx++;
    }

out:
    if (curidx == index)
        return op;
    return NULL;
}

struct bbc_i2c_client *bbc_i2c_attach(struct bbc_i2c_bus *bp, struct platform_device *op)
{
    struct bbc_i2c_client *client;
    const u32 *reg;

    client = kzalloc(sizeof(*client), GFP_KERNEL);
    if (!client)
        return NULL;
    client->bp = bp;
    client->op = op;

    reg = of_get_property(op->dev.of_node, "reg", NULL);
    if (!reg) {
        kfree(client);
        return NULL;
    }

    client->bus = reg[0];
    client->address = reg[1];

    claim_device(bp, op);

    return client;
}

void bbc_i2c_detach(struct bbc_i2c_client *client)
{
    struct bbc_i2c_bus *bp = client->bp;
    struct platform_device *op = client->op;

    release_device(bp, op);
    kfree(client);
}

static int wait_for_pin(struct bbc_i2c_bus *bp, u8 *status)
{
    DECLARE_WAITQUEUE(wait, current);
    int limit = 32;
    int ret = 1;

    bp->waiting = 1;
    add_wait_queue(&bp->wq, &wait);
    while (limit-- > 0) {
        long val;

        val = wait_event_interruptible_timeout(
                bp->wq,
                (((*status = readb(bp->i2c_control_regs + 0))
                  & I2C_PCF_PIN) == 0),
                msecs_to_jiffies(250));
        if (val > 0) {
            ret = 0;
            break;
        }
    }
    remove_wait_queue(&bp->wq, &wait);
    bp->waiting = 0;

    return ret;
}

int bbc_i2c_writeb(struct bbc_i2c_client *client, unsigned char val, int off)
{
    struct bbc_i2c_bus *bp = client->bp;
    int address = client->address;
    u8 status;
    int ret = -1;

    if (bp->i2c_bussel_reg != NULL)
        writeb(client->bus, bp->i2c_bussel_reg);

    writeb(address, bp->i2c_control_regs + 0x1);
    writeb(I2C_PCF_START, bp->i2c_control_regs + 0x0);
    if (wait_for_pin(bp, &status))
        goto out;

    writeb(off, bp->i2c_control_regs + 0x1);
    if (wait_for_pin(bp, &status) ||
        (status & I2C_PCF_LRB) != 0)
        goto out;

    writeb(val, bp->i2c_control_regs + 0x1);
    if (wait_for_pin(bp, &status))
        goto out;

    ret = 0;

out:
    writeb(I2C_PCF_STOP, bp->i2c_control_regs + 0x0);
    return ret;
}

int bbc_i2c_readb(struct bbc_i2c_client *client, unsigned char *byte, int off)
{
    struct bbc_i2c_bus *bp = client->bp;
    unsigned char address = client->address, status;
    int ret = -1;

    if (bp->i2c_bussel_reg != NULL)
        writeb(client->bus, bp->i2c_bussel_reg);

    writeb(address, bp->i2c_control_regs + 0x1);
    writeb(I2C_PCF_START, bp->i2c_control_regs + 0x0);
    if (wait_for_pin(bp, &status))
        goto out;

    writeb(off, bp->i2c_control_regs + 0x1);
    if (wait_for_pin(bp, &status) ||
        (status & I2C_PCF_LRB) != 0)
        goto out;

    writeb(I2C_PCF_STOP, bp->i2c_control_regs + 0x0);

    address |= 0x1; /* READ */

    writeb(address, bp->i2c_control_regs + 0x1);
    writeb(I2C_PCF_START, bp->i2c_control_regs + 0x0);
    if (wait_for_pin(bp, &status))
        goto out;

    /* Set PIN back to one so the device sends the first
     * byte.
     */
    (void) readb(bp->i2c_control_regs + 0x1);
    if (wait_for_pin(bp, &status))
        goto out;

    writeb(I2C_PCF_ESO | I2C_PCF_ENI, bp->i2c_control_regs + 0x0);
    *byte = readb(bp->i2c_control_regs + 0x1);
    if (wait_for_pin(bp, &status))
        goto out;

    ret = 0;

out:
    writeb(I2C_PCF_STOP, bp->i2c_control_regs + 0x0);
    (void) readb(bp->i2c_control_regs + 0x1);

    return ret;
}

int bbc_i2c_write_buf(struct bbc_i2c_client *client,
              char *buf, int len, int off)
{
    int ret = 0;

    while (len > 0) {
        ret = bbc_i2c_writeb(client, *buf, off);
        if (ret < 0)
            break;
        len--;
        buf++;
        off++;
    }
    return ret;
}

int bbc_i2c_read_buf(struct bbc_i2c_client *client,
             char *buf, int len, int off)
{
    int ret = 0;

    while (len > 0) {
        ret = bbc_i2c_readb(client, buf, off);
        if (ret < 0)
            break;
        len--;
        buf++;
        off++;
    }

    return ret;
}

EXPORT_SYMBOL(bbc_i2c_getdev);
EXPORT_SYMBOL(bbc_i2c_attach);
EXPORT_SYMBOL(bbc_i2c_detach);
EXPORT_SYMBOL(bbc_i2c_writeb);
EXPORT_SYMBOL(bbc_i2c_readb);
EXPORT_SYMBOL(bbc_i2c_write_buf);
EXPORT_SYMBOL(bbc_i2c_read_buf);

static irqreturn_t bbc_i2c_interrupt(int irq, void *dev_id)
{
    struct bbc_i2c_bus *bp = dev_id;

    /* PIN going from set to clear is the only event which
     * makes the i2c assert an interrupt.
     */
    if (bp->waiting &&
        !(readb(bp->i2c_control_regs + 0x0) & I2C_PCF_PIN))
        wake_up_interruptible(&bp->wq);

    return IRQ_HANDLED;
}

static void __init reset_one_i2c(struct bbc_i2c_bus *bp)
{
    writeb(I2C_PCF_PIN, bp->i2c_control_regs + 0x0);
    writeb(bp->own, bp->i2c_control_regs + 0x1);
    writeb(I2C_PCF_PIN | I2C_PCF_ES1, bp->i2c_control_regs + 0x0);
    writeb(bp->clock, bp->i2c_control_regs + 0x1);
    writeb(I2C_PCF_IDLE, bp->i2c_control_regs + 0x0);
}

static struct bbc_i2c_bus * __init attach_one_i2c(struct platform_device *op, int index)
{
    struct bbc_i2c_bus *bp;
    struct device_node *dp;
    int entry;

    bp = kzalloc(sizeof(*bp), GFP_KERNEL);
    if (!bp)
        return NULL;

    bp->i2c_control_regs = of_ioremap(&op->resource[0], 0, 0x2, "bbc_i2c_regs");
    if (!bp->i2c_control_regs)
        goto fail;

    bp->i2c_bussel_reg = of_ioremap(&op->resource[1], 0, 0x1, "bbc_i2c_bussel");
    if (!bp->i2c_bussel_reg)
        goto fail;

    bp->waiting = 0;
    init_waitqueue_head(&bp->wq);
    if (request_irq(op->archdata.irqs[0], bbc_i2c_interrupt,
            IRQF_SHARED, "bbc_i2c", bp))
        goto fail;

    bp->index = index;
    bp->op = op;

    spin_lock_init(&bp->lock);

    entry = 0;
    for (dp = op->dev.of_node->child;
         dp && entry < 8;
         dp = dp->sibling, entry++) {
        struct platform_device *child_op;

        child_op = of_find_device_by_node(dp);
        bp->devs[entry].device = child_op;
        bp->devs[entry].client_claimed = 0;
    }

    writeb(I2C_PCF_PIN, bp->i2c_control_regs + 0x0);
    bp->own = readb(bp->i2c_control_regs + 0x01);
    writeb(I2C_PCF_PIN | I2C_PCF_ES1, bp->i2c_control_regs + 0x0);
    bp->clock = readb(bp->i2c_control_regs + 0x01);

    printk(KERN_INFO "i2c-%d: Regs at %p, %d devices, own %02x, clock %02x.\n",
           bp->index, bp->i2c_control_regs, entry, bp->own, bp->clock);

    reset_one_i2c(bp);

    return bp;

fail:
    if (bp->i2c_bussel_reg)
        of_iounmap(&op->resource[1], bp->i2c_bussel_reg, 1);
    if (bp->i2c_control_regs)
        of_iounmap(&op->resource[0], bp->i2c_control_regs, 2);
    kfree(bp);
    return NULL;
}

extern int bbc_envctrl_init(struct bbc_i2c_bus *bp);
extern void bbc_envctrl_cleanup(struct bbc_i2c_bus *bp);

static int __devinit bbc_i2c_probe(struct platform_device *op)
{
    struct bbc_i2c_bus *bp;
    int err, index = 0;

    bp = attach_one_i2c(op, index);
    if (!bp)
        return -EINVAL;

    err = bbc_envctrl_init(bp);
    if (err) {
        free_irq(op->archdata.irqs[0], bp);
        if (bp->i2c_bussel_reg)
            of_iounmap(&op->resource[0], bp->i2c_bussel_reg, 1);
        if (bp->i2c_control_regs)
            of_iounmap(&op->resource[1], bp->i2c_control_regs, 2);
        kfree(bp);
    } else {
        dev_set_drvdata(&op->dev, bp);
    }

    return err;
}

static int __devexit bbc_i2c_remove(struct platform_device *op)
{
    struct bbc_i2c_bus *bp = dev_get_drvdata(&op->dev);

    bbc_envctrl_cleanup(bp);

    free_irq(op->archdata.irqs[0], bp);

    if (bp->i2c_bussel_reg)
        of_iounmap(&op->resource[0], bp->i2c_bussel_reg, 1);
    if (bp->i2c_control_regs)
        of_iounmap(&op->resource[1], bp->i2c_control_regs, 2);

    kfree(bp);

    return 0;
}

static const struct of_device_id bbc_i2c_match[] = {
    {
        .name = "i2c",
        .compatible = "SUNW,bbc-i2c",
    },
    {},
};
MODULE_DEVICE_TABLE(of, bbc_i2c_match);

static struct platform_driver bbc_i2c_driver = {
    .driver = {
        .name = "bbc_i2c",
        .owner = THIS_MODULE,
        .of_match_table = bbc_i2c_match,
    },
    .probe      = bbc_i2c_probe,
    .remove     = __devexit_p(bbc_i2c_remove),
};

module_platform_driver(bbc_i2c_driver);

MODULE_LICENSE("GPL");