271 lines
6.1 KiB
C
271 lines
6.1 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
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/* display7seg.c - Driver implementation for the 7-segment display
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* present on Sun Microsystems CP1400 and CP1500
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*
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* Copyright (c) 2000 Eric Brower (ebrower@usa.net)
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*/
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#include <linux/device.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/errno.h>
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#include <linux/major.h>
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#include <linux/miscdevice.h>
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#include <linux/ioport.h> /* request_region */
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#include <linux/slab.h>
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#include <linux/mutex.h>
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#include <linux/of.h>
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#include <linux/of_device.h>
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#include <linux/atomic.h>
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#include <linux/uaccess.h> /* put_/get_user */
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#include <asm/io.h>
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#include <asm/display7seg.h>
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#define DRIVER_NAME "d7s"
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#define PFX DRIVER_NAME ": "
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static DEFINE_MUTEX(d7s_mutex);
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static int sol_compat = 0; /* Solaris compatibility mode */
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/* Solaris compatibility flag -
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* The Solaris implementation omits support for several
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* documented driver features (ref Sun doc 806-0180-03).
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* By default, this module supports the documented driver
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* abilities, rather than the Solaris implementation:
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*
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* 1) Device ALWAYS reverts to OBP-specified FLIPPED mode
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* upon closure of device or module unload.
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* 2) Device ioctls D7SIOCRD/D7SIOCWR honor toggling of
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* FLIP bit
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*
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* If you wish the device to operate as under Solaris,
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* omitting above features, set this parameter to non-zero.
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*/
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module_param(sol_compat, int, 0);
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MODULE_PARM_DESC(sol_compat,
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"Disables documented functionality omitted from Solaris driver");
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MODULE_AUTHOR("Eric Brower <ebrower@usa.net>");
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MODULE_DESCRIPTION("7-Segment Display driver for Sun Microsystems CP1400/1500");
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MODULE_LICENSE("GPL");
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struct d7s {
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void __iomem *regs;
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bool flipped;
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};
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struct d7s *d7s_device;
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/*
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* Register block address- see header for details
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* -----------------------------------------
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* | DP | ALARM | FLIP | 4 | 3 | 2 | 1 | 0 |
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* -----------------------------------------
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*
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* DP - Toggles decimal point on/off
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* ALARM - Toggles "Alarm" LED green/red
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* FLIP - Inverts display for upside-down mounted board
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* bits 0-4 - 7-segment display contents
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*/
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static atomic_t d7s_users = ATOMIC_INIT(0);
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static int d7s_open(struct inode *inode, struct file *f)
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{
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if (D7S_MINOR != iminor(inode))
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return -ENODEV;
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atomic_inc(&d7s_users);
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return 0;
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}
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static int d7s_release(struct inode *inode, struct file *f)
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{
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/* Reset flipped state to OBP default only if
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* no other users have the device open and we
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* are not operating in solaris-compat mode
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*/
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if (atomic_dec_and_test(&d7s_users) && !sol_compat) {
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struct d7s *p = d7s_device;
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u8 regval = 0;
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regval = readb(p->regs);
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if (p->flipped)
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regval |= D7S_FLIP;
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else
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regval &= ~D7S_FLIP;
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writeb(regval, p->regs);
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}
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return 0;
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}
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static long d7s_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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{
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struct d7s *p = d7s_device;
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u8 regs = readb(p->regs);
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int error = 0;
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u8 ireg = 0;
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if (D7S_MINOR != iminor(file_inode(file)))
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return -ENODEV;
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mutex_lock(&d7s_mutex);
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switch (cmd) {
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case D7SIOCWR:
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/* assign device register values we mask-out D7S_FLIP
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* if in sol_compat mode
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*/
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if (get_user(ireg, (int __user *) arg)) {
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error = -EFAULT;
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break;
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}
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if (sol_compat) {
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if (regs & D7S_FLIP)
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ireg |= D7S_FLIP;
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else
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ireg &= ~D7S_FLIP;
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}
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writeb(ireg, p->regs);
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break;
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case D7SIOCRD:
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/* retrieve device register values
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* NOTE: Solaris implementation returns D7S_FLIP bit
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* as toggled by user, even though it does not honor it.
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* This driver will not misinform you about the state
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* of your hardware while in sol_compat mode
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*/
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if (put_user(regs, (int __user *) arg)) {
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error = -EFAULT;
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break;
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}
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break;
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case D7SIOCTM:
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/* toggle device mode-- flip display orientation */
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regs ^= D7S_FLIP;
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writeb(regs, p->regs);
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break;
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}
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mutex_unlock(&d7s_mutex);
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return error;
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}
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static const struct file_operations d7s_fops = {
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.owner = THIS_MODULE,
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.unlocked_ioctl = d7s_ioctl,
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.compat_ioctl = compat_ptr_ioctl,
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.open = d7s_open,
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.release = d7s_release,
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.llseek = noop_llseek,
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};
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static struct miscdevice d7s_miscdev = {
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.minor = D7S_MINOR,
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.name = DRIVER_NAME,
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.fops = &d7s_fops
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};
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static int d7s_probe(struct platform_device *op)
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{
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struct device_node *opts;
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int err = -EINVAL;
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struct d7s *p;
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u8 regs;
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if (d7s_device)
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goto out;
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p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL);
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err = -ENOMEM;
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if (!p)
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goto out;
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p->regs = of_ioremap(&op->resource[0], 0, sizeof(u8), "d7s");
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if (!p->regs) {
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printk(KERN_ERR PFX "Cannot map chip registers\n");
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goto out;
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}
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err = misc_register(&d7s_miscdev);
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if (err) {
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printk(KERN_ERR PFX "Unable to acquire miscdevice minor %i\n",
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D7S_MINOR);
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goto out_iounmap;
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}
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/* OBP option "d7s-flipped?" is honored as default for the
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* device, and reset default when detached
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*/
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regs = readb(p->regs);
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opts = of_find_node_by_path("/options");
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if (opts &&
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of_get_property(opts, "d7s-flipped?", NULL))
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p->flipped = true;
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if (p->flipped)
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regs |= D7S_FLIP;
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else
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regs &= ~D7S_FLIP;
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writeb(regs, p->regs);
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printk(KERN_INFO PFX "7-Segment Display%pOF at [%s:0x%llx] %s\n",
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op->dev.of_node,
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(regs & D7S_FLIP) ? " (FLIPPED)" : "",
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op->resource[0].start,
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sol_compat ? "in sol_compat mode" : "");
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dev_set_drvdata(&op->dev, p);
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d7s_device = p;
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err = 0;
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of_node_put(opts);
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out:
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return err;
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out_iounmap:
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of_iounmap(&op->resource[0], p->regs, sizeof(u8));
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goto out;
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}
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static int d7s_remove(struct platform_device *op)
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{
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struct d7s *p = dev_get_drvdata(&op->dev);
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u8 regs = readb(p->regs);
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/* Honor OBP d7s-flipped? unless operating in solaris-compat mode */
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if (sol_compat) {
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if (p->flipped)
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regs |= D7S_FLIP;
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else
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regs &= ~D7S_FLIP;
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writeb(regs, p->regs);
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}
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misc_deregister(&d7s_miscdev);
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of_iounmap(&op->resource[0], p->regs, sizeof(u8));
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return 0;
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}
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static const struct of_device_id d7s_match[] = {
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{
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.name = "display7seg",
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},
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{},
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};
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MODULE_DEVICE_TABLE(of, d7s_match);
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static struct platform_driver d7s_driver = {
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.driver = {
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.name = DRIVER_NAME,
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.of_match_table = d7s_match,
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},
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.probe = d7s_probe,
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.remove = d7s_remove,
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};
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module_platform_driver(d7s_driver);
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