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