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