display7seg.c

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/* display7seg.c - Driver implementation for the 7-segment display
 *                 present on Sun Microsystems CP1400 and CP1500
 *
 * Copyright (c) 2000 Eric Brower ([email protected])
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/major.h>
#include <linux/init.h>
#include <linux/miscdevice.h>
#include <linux/ioport.h>       /* request_region */
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/atomic.h>
#include <asm/uaccess.h>        /* put_/get_user            */
#include <asm/io.h>

#include <asm/display7seg.h>

#define D7S_MINOR   193
#define DRIVER_NAME "d7s"
#define PFX     DRIVER_NAME ": "

static DEFINE_MUTEX(d7s_mutex);
static int sol_compat = 0;      /* Solaris compatibility mode   */

/* Solaris compatibility flag -
 * The Solaris implementation omits support for several
 * documented driver features (ref Sun doc 806-0180-03).  
 * By default, this module supports the documented driver 
 * abilities, rather than the Solaris implementation:
 *
 *  1) Device ALWAYS reverts to OBP-specified FLIPPED mode
 *     upon closure of device or module unload.
 *  2) Device ioctls D7SIOCRD/D7SIOCWR honor toggling of
 *     FLIP bit
 *
 * If you wish the device to operate as under Solaris,
 * omitting above features, set this parameter to non-zero.
 */
module_param(sol_compat, int, 0);
MODULE_PARM_DESC(sol_compat, 
         "Disables documented functionality omitted from Solaris driver");

MODULE_AUTHOR("Eric Brower <[email protected]>");
MODULE_DESCRIPTION("7-Segment Display driver for Sun Microsystems CP1400/1500");
MODULE_LICENSE("GPL");
MODULE_SUPPORTED_DEVICE("d7s");

struct d7s {
    void __iomem    *regs;
    bool        flipped;
};
struct d7s *d7s_device;

/*
 * Register block address- see header for details
 * -----------------------------------------
 * | DP | ALARM | FLIP | 4 | 3 | 2 | 1 | 0 |
 * -----------------------------------------
 *
 * DP       - Toggles decimal point on/off 
 * ALARM    - Toggles "Alarm" LED green/red
 * FLIP     - Inverts display for upside-down mounted board
 * bits 0-4 - 7-segment display contents
 */
static atomic_t d7s_users = ATOMIC_INIT(0);

static int d7s_open(struct inode *inode, struct file *f)
{
    if (D7S_MINOR != iminor(inode))
        return -ENODEV;
    atomic_inc(&d7s_users);
    return 0;
}

static int d7s_release(struct inode *inode, struct file *f)
{
    /* Reset flipped state to OBP default only if
     * no other users have the device open and we
     * are not operating in solaris-compat mode
     */
    if (atomic_dec_and_test(&d7s_users) && !sol_compat) {
        struct d7s *p = d7s_device;
        u8 regval = 0;

        regval = readb(p->regs);
        if (p->flipped)
            regval |= D7S_FLIP;
        else
            regval &= ~D7S_FLIP;
        writeb(regval, p->regs);
    }

    return 0;
}

static long d7s_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    struct d7s *p = d7s_device;
    u8 regs = readb(p->regs);
    int error = 0;
    u8 ireg = 0;

    if (D7S_MINOR != iminor(file->f_path.dentry->d_inode))
        return -ENODEV;

    mutex_lock(&d7s_mutex);
    switch (cmd) {
    case D7SIOCWR:
        /* assign device register values we mask-out D7S_FLIP
         * if in sol_compat mode
         */
        if (get_user(ireg, (int __user *) arg)) {
            error = -EFAULT;
            break;
        }
        if (sol_compat) {
            if (regs & D7S_FLIP)
                ireg |= D7S_FLIP;
            else
                ireg &= ~D7S_FLIP;
        }
        writeb(ireg, p->regs);
        break;

    case D7SIOCRD:
        /* retrieve device register values
         * NOTE: Solaris implementation returns D7S_FLIP bit
         * as toggled by user, even though it does not honor it.
         * This driver will not misinform you about the state
         * of your hardware while in sol_compat mode
         */
        if (put_user(regs, (int __user *) arg)) {
            error = -EFAULT;
            break;
        }
        break;

    case D7SIOCTM:
        /* toggle device mode-- flip display orientation */
        if (regs & D7S_FLIP)
            regs &= ~D7S_FLIP;
        else
            regs |= D7S_FLIP;
        writeb(regs, p->regs);
        break;
    }
    mutex_unlock(&d7s_mutex);

    return error;
}

static const struct file_operations d7s_fops = {
    .owner =        THIS_MODULE,
    .unlocked_ioctl =   d7s_ioctl,
    .compat_ioctl =     d7s_ioctl,
    .open =         d7s_open,
    .release =      d7s_release,
    .llseek = noop_llseek,
};

static struct miscdevice d7s_miscdev = {
    .minor      = D7S_MINOR,
    .name       = DRIVER_NAME,
    .fops       = &d7s_fops
};

static int __devinit d7s_probe(struct platform_device *op)
{
    struct device_node *opts;
    int err = -EINVAL;
    struct d7s *p;
    u8 regs;

    if (d7s_device)
        goto out;

    p = kzalloc(sizeof(*p), GFP_KERNEL);
    err = -ENOMEM;
    if (!p)
        goto out;

    p->regs = of_ioremap(&op->resource[0], 0, sizeof(u8), "d7s");
    if (!p->regs) {
        printk(KERN_ERR PFX "Cannot map chip registers\n");
        goto out_free;
    }

    err = misc_register(&d7s_miscdev);
    if (err) {
        printk(KERN_ERR PFX "Unable to acquire miscdevice minor %i\n",
               D7S_MINOR);
        goto out_iounmap;
    }

    /* OBP option "d7s-flipped?" is honored as default for the
     * device, and reset default when detached
     */
    regs = readb(p->regs);
    opts = of_find_node_by_path("/options");
    if (opts &&
        of_get_property(opts, "d7s-flipped?", NULL))
        p->flipped = true;

    if (p->flipped)
        regs |= D7S_FLIP;
    else
        regs &= ~D7S_FLIP;

    writeb(regs,  p->regs);

    printk(KERN_INFO PFX "7-Segment Display%s at [%s:0x%llx] %s\n",
           op->dev.of_node->full_name,
           (regs & D7S_FLIP) ? " (FLIPPED)" : "",
           op->resource[0].start,
           sol_compat ? "in sol_compat mode" : "");

    dev_set_drvdata(&op->dev, p);
    d7s_device = p;
    err = 0;

out:
    return err;

out_iounmap:
    of_iounmap(&op->resource[0], p->regs, sizeof(u8));

out_free:
    kfree(p);
    goto out;
}

static int __devexit d7s_remove(struct platform_device *op)
{
    struct d7s *p = dev_get_drvdata(&op->dev);
    u8 regs = readb(p->regs);

    /* Honor OBP d7s-flipped? unless operating in solaris-compat mode */
    if (sol_compat) {
        if (p->flipped)
            regs |= D7S_FLIP;
        else
            regs &= ~D7S_FLIP;
        writeb(regs, p->regs);
    }

    misc_deregister(&d7s_miscdev);
    of_iounmap(&op->resource[0], p->regs, sizeof(u8));
    kfree(p);

    return 0;
}

static const struct of_device_id d7s_match[] = {
    {
        .name = "display7seg",
    },
    {},
};
MODULE_DEVICE_TABLE(of, d7s_match);

static struct platform_driver d7s_driver = {
    .driver = {
        .name = DRIVER_NAME,
        .owner = THIS_MODULE,
        .of_match_table = d7s_match,
    },
    .probe      = d7s_probe,
    .remove     = __devexit_p(d7s_remove),
};

module_platform_driver(d7s_driver);