drivers/sbus/char/display7seg.c

   1 /* $Id: display7seg.c,v 1.6 2002/01/08 16:00:16 davem Exp $
   2  *
   3  * display7seg - Driver implementation for the 7-segment display
   4  * present on Sun Microsystems CP1400 and CP1500
   5  *
   6  * Copyright (c) 2000 Eric Brower (ebrower@usa.net)
   7  *
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/fs.h>
  13 #include <linux/errno.h>
  14 #include <linux/major.h>
  15 #include <linux/init.h>
  16 #include <linux/miscdevice.h>
  17 #include <linux/ioport.h>               /* request_region */
  18 #include <linux/smp_lock.h>
  19 #include <asm/atomic.h>
  20 #include <asm/ebus.h>                   /* EBus device                                  */
  21 #include <asm/oplib.h>                  /* OpenProm Library                     */
  22 #include <asm/uaccess.h>                /* put_/get_user                        */
  23 #include <asm/io.h>
  24
  25 #include <asm/display7seg.h>
  26
  27 #define D7S_MINOR       193
  28 #define D7S_OBPNAME     "display7seg"
  29 #define D7S_DEVNAME "d7s"
  30
  31 static int sol_compat = 0;              /* Solaris compatibility mode   */
  32
  33 #ifdef MODULE
  34
  35 /* Solaris compatibility flag -
  36  * The Solaris implementation omits support for several
  37  * documented driver features (ref Sun doc 806-0180-03).
  38  * By default, this module supports the documented driver
  39  * abilities, rather than the Solaris implementation:
  40  *
  41  *      1) Device ALWAYS reverts to OBP-specified FLIPPED mode
  42  *         upon closure of device or module unload.
  43  *      2) Device ioctls D7SIOCRD/D7SIOCWR honor toggling of
  44  *         FLIP bit
  45  *
  46  * If you wish the device to operate as under Solaris,
  47  * omitting above features, set this parameter to non-zero.
  48  */
  49 module_param
  50         (sol_compat, int, 0);
  51 MODULE_PARM_DESC
  52         (sol_compat,
  53          "Disables documented functionality omitted from Solaris driver");
  54
  55 MODULE_AUTHOR
  56         ("Eric Brower <ebrower@usa.net>");
  57 MODULE_DESCRIPTION
  58         ("7-Segment Display driver for Sun Microsystems CP1400/1500");
  59 MODULE_LICENSE("GPL");
  60 MODULE_SUPPORTED_DEVICE
  61         ("d7s");
  62 #endif /* ifdef MODULE */
  63
  64 /*
  65  * Register block address- see header for details
  66  * -----------------------------------------
  67  * | DP | ALARM | FLIP | 4 | 3 | 2 | 1 | 0 |
  68  * -----------------------------------------
  69  *
  70  * DP           - Toggles decimal point on/off
  71  * ALARM        - Toggles "Alarm" LED green/red
  72  * FLIP         - Inverts display for upside-down mounted board
  73  * bits 0-4     - 7-segment display contents
  74  */
  75 static void __iomem* d7s_regs;
  76
  77 static inline void d7s_free(void)
  78 {
  79         iounmap(d7s_regs);
  80 }
  81
  82 static inline int d7s_obpflipped(void)
  83 {
  84         int opt_node;
  85
  86         opt_node = prom_getchild(prom_root_node);
  87         opt_node = prom_searchsiblings(opt_node, "options");
  88         return ((-1 != prom_getintdefault(opt_node, "d7s-flipped?", -1)) ? 0 : 1);
  89 }
  90
  91 static atomic_t d7s_users = ATOMIC_INIT(0);
  92
  93 static int d7s_open(struct inode *inode, struct file *f)
  94 {
  95         if (D7S_MINOR != iminor(inode))
  96                 return -ENODEV;
  97         atomic_inc(&d7s_users);
  98         return 0;
  99 }
 100
 101 static int d7s_release(struct inode *inode, struct file *f)
 102 {
 103         /* Reset flipped state to OBP default only if
 104          * no other users have the device open and we
 105          * are not operating in solaris-compat mode
 106          */
 107         if (atomic_dec_and_test(&d7s_users) && !sol_compat) {
 108                 int regval = 0;
 109
 110                 regval = readb(d7s_regs);
 111                 (0 == d7s_obpflipped()) ?
 112                         writeb(regval |= D7S_FLIP,  d7s_regs):
 113                         writeb(regval &= ~D7S_FLIP, d7s_regs);
 114         }
 115
 116         return 0;
 117 }
 118
 119 static long d7s_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 120 {
 121         __u8 regs = readb(d7s_regs);
 122         __u8 ireg = 0;
 123         int error = 0;
 124
 125         if (D7S_MINOR != iminor(file->f_path.dentry->d_inode))
 126                 return -ENODEV;
 127
 128         lock_kernel();
 129         switch (cmd) {
 130         case D7SIOCWR:
 131                 /* assign device register values
 132                  * we mask-out D7S_FLIP if in sol_compat mode
 133                  */
 134                 if (get_user(ireg, (int __user *) arg)) {
 135                         error = -EFAULT;
 136                         break;
 137                 }
 138                 if (0 != sol_compat) {
 139                         (regs & D7S_FLIP) ?
 140                                 (ireg |= D7S_FLIP) : (ireg &= ~D7S_FLIP);
 141                 }
 142                 writeb(ireg, d7s_regs);
 143                 break;
 144
 145         case D7SIOCRD:
 146                 /* retrieve device register values
 147                  * NOTE: Solaris implementation returns D7S_FLIP bit
 148                  * as toggled by user, even though it does not honor it.
 149                  * This driver will not misinform you about the state
 150                  * of your hardware while in sol_compat mode
 151                  */
 152                 if (put_user(regs, (int __user *) arg)) {
 153                         error = -EFAULT;
 154                         break;
 155                 }
 156                 break;
 157
 158         case D7SIOCTM:
 159                 /* toggle device mode-- flip display orientation */
 160                 (regs & D7S_FLIP) ?
 161                         (regs &= ~D7S_FLIP) : (regs |= D7S_FLIP);
 162                 writeb(regs, d7s_regs);
 163                 break;
 164         };
 165         unlock_kernel();
 166
 167         return error;
 168 }
 169
 170 static const struct file_operations d7s_fops = {
 171         .owner =                THIS_MODULE,
 172         .unlocked_ioctl =       d7s_ioctl,
 173         .compat_ioctl =         d7s_ioctl,
 174         .open =                 d7s_open,
 175         .release =              d7s_release,
 176 };
 177
 178 static struct miscdevice d7s_miscdev = { D7S_MINOR, D7S_DEVNAME, &d7s_fops };
 179
 180 static int __init d7s_init(void)
 181 {
 182         struct linux_ebus *ebus = NULL;
 183         struct linux_ebus_device *edev = NULL;
 184         int iTmp = 0, regs = 0;
 185
 186         for_each_ebus(ebus) {
 187                 for_each_ebusdev(edev, ebus) {
 188                         if (!strcmp(edev->prom_node->name, D7S_OBPNAME))
 189                                 goto ebus_done;
 190                 }
 191         }
 192
 193 ebus_done:
 194         if(!edev) {
 195                 printk("%s: unable to locate device\n", D7S_DEVNAME);
 196                 return -ENODEV;
 197         }
 198
 199         d7s_regs = ioremap(edev->resource[0].start, sizeof(__u8));
 200
 201         iTmp = misc_register(&d7s_miscdev);
 202         if (0 != iTmp) {
 203                 printk("%s: unable to acquire miscdevice minor %i\n",
 204                        D7S_DEVNAME, D7S_MINOR);
 205                 iounmap(d7s_regs);
 206                 return iTmp;
 207         }
 208
 209         /* OBP option "d7s-flipped?" is honored as default
 210          * for the device, and reset default when detached
 211          */
 212         regs = readb(d7s_regs);
 213         iTmp = d7s_obpflipped();
 214         (0 == iTmp) ?
 215                 writeb(regs |= D7S_FLIP,  d7s_regs):
 216                 writeb(regs &= ~D7S_FLIP, d7s_regs);
 217
 218         printk("%s: 7-Segment Display%s at 0x%lx %s\n",
 219                D7S_DEVNAME,
 220                (0 == iTmp) ? (" (FLIPPED)") : (""),
 221                edev->resource[0].start,
 222                (0 != sol_compat) ? ("in sol_compat mode") : (""));
 223
 224         return 0;
 225 }
 226
 227 static void __exit d7s_cleanup(void)
 228 {
 229         int regs = readb(d7s_regs);
 230
 231         /* Honor OBP d7s-flipped? unless operating in solaris-compat mode */
 232         if (0 == sol_compat) {
 233                 (0 == d7s_obpflipped()) ?
 234                         writeb(regs |= D7S_FLIP,  d7s_regs):
 235                         writeb(regs &= ~D7S_FLIP, d7s_regs);
 236         }
 237
 238         misc_deregister(&d7s_miscdev);
 239         d7s_free();
 240 }
 241
 242 module_init(d7s_init);
 243 module_exit(d7s_cleanup);