drivers/sbus/char/display7seg.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* display7seg.c - Driver implementation for the 7-segment display
   3  *                 present on Sun Microsystems CP1400 and CP1500
   4  *
   5  * Copyright (c) 2000 Eric Brower (ebrower@usa.net)
   6  */
   7
   8 #include <linux/device.h>
   9 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <linux/fs.h>
  12 #include <linux/errno.h>
  13 #include <linux/major.h>
  14 #include <linux/miscdevice.h>
  15 #include <linux/ioport.h>               /* request_region */
  16 #include <linux/slab.h>
  17 #include <linux/mutex.h>
  18 #include <linux/of.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/atomic.h>
  21 #include <linux/uaccess.h>              /* put_/get_user                        */
  22 #include <asm/io.h>
  23
  24 #include <asm/display7seg.h>
  25
  26 #define DRIVER_NAME     "d7s"
  27 #define PFX             DRIVER_NAME ": "
  28
  29 static DEFINE_MUTEX(d7s_mutex);
  30 static int sol_compat = 0;              /* Solaris compatibility mode   */
  31
  32 /* Solaris compatibility flag -
  33  * The Solaris implementation omits support for several
  34  * documented driver features (ref Sun doc 806-0180-03).
  35  * By default, this module supports the documented driver
  36  * abilities, rather than the Solaris implementation:
  37  *
  38  *      1) Device ALWAYS reverts to OBP-specified FLIPPED mode
  39  *         upon closure of device or module unload.
  40  *      2) Device ioctls D7SIOCRD/D7SIOCWR honor toggling of
  41  *         FLIP bit
  42  *
  43  * If you wish the device to operate as under Solaris,
  44  * omitting above features, set this parameter to non-zero.
  45  */
  46 module_param(sol_compat, int, 0);
  47 MODULE_PARM_DESC(sol_compat,
  48                  "Disables documented functionality omitted from Solaris driver");
  49
  50 MODULE_AUTHOR("Eric Brower <ebrower@usa.net>");
  51 MODULE_DESCRIPTION("7-Segment Display driver for Sun Microsystems CP1400/1500");
  52 MODULE_LICENSE("GPL");
  53
  54 struct d7s {
  55         void __iomem    *regs;
  56         bool            flipped;
  57 };
  58 struct d7s *d7s_device;
  59
  60 /*
  61  * Register block address- see header for details
  62  * -----------------------------------------
  63  * | DP | ALARM | FLIP | 4 | 3 | 2 | 1 | 0 |
  64  * -----------------------------------------
  65  *
  66  * DP           - Toggles decimal point on/off
  67  * ALARM        - Toggles "Alarm" LED green/red
  68  * FLIP         - Inverts display for upside-down mounted board
  69  * bits 0-4     - 7-segment display contents
  70  */
  71 static atomic_t d7s_users = ATOMIC_INIT(0);
  72
  73 static int d7s_open(struct inode *inode, struct file *f)
  74 {
  75         if (D7S_MINOR != iminor(inode))
  76                 return -ENODEV;
  77         atomic_inc(&d7s_users);
  78         return 0;
  79 }
  80
  81 static int d7s_release(struct inode *inode, struct file *f)
  82 {
  83         /* Reset flipped state to OBP default only if
  84          * no other users have the device open and we
  85          * are not operating in solaris-compat mode
  86          */
  87         if (atomic_dec_and_test(&d7s_users) && !sol_compat) {
  88                 struct d7s *p = d7s_device;
  89                 u8 regval = 0;
  90
  91                 regval = readb(p->regs);
  92                 if (p->flipped)
  93                         regval |= D7S_FLIP;
  94                 else
  95                         regval &= ~D7S_FLIP;
  96                 writeb(regval, p->regs);
  97         }
  98
  99         return 0;
 100 }
 101
 102 static long d7s_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 103 {
 104         struct d7s *p = d7s_device;
 105         u8 regs = readb(p->regs);
 106         int error = 0;
 107         u8 ireg = 0;
 108
 109         if (D7S_MINOR != iminor(file_inode(file)))
 110                 return -ENODEV;
 111
 112         mutex_lock(&d7s_mutex);
 113         switch (cmd) {
 114         case D7SIOCWR:
 115                 /* assign device register values we mask-out D7S_FLIP
 116                  * if in sol_compat mode
 117                  */
 118                 if (get_user(ireg, (int __user *) arg)) {
 119                         error = -EFAULT;
 120                         break;
 121                 }
 122                 if (sol_compat) {
 123                         if (regs & D7S_FLIP)
 124                                 ireg |= D7S_FLIP;
 125                         else
 126                                 ireg &= ~D7S_FLIP;
 127                 }
 128                 writeb(ireg, p->regs);
 129                 break;
 130
 131         case D7SIOCRD:
 132                 /* retrieve device register values
 133                  * NOTE: Solaris implementation returns D7S_FLIP bit
 134                  * as toggled by user, even though it does not honor it.
 135                  * This driver will not misinform you about the state
 136                  * of your hardware while in sol_compat mode
 137                  */
 138                 if (put_user(regs, (int __user *) arg)) {
 139                         error = -EFAULT;
 140                         break;
 141                 }
 142                 break;
 143
 144         case D7SIOCTM:
 145                 /* toggle device mode-- flip display orientation */
 146                 regs ^= D7S_FLIP;
 147                 writeb(regs, p->regs);
 148                 break;
 149         }
 150         mutex_unlock(&d7s_mutex);
 151
 152         return error;
 153 }
 154
 155 static const struct file_operations d7s_fops = {
 156         .owner =                THIS_MODULE,
 157         .unlocked_ioctl =       d7s_ioctl,
 158         .compat_ioctl =         compat_ptr_ioctl,
 159         .open =                 d7s_open,
 160         .release =              d7s_release,
 161         .llseek = noop_llseek,
 162 };
 163
 164 static struct miscdevice d7s_miscdev = {
 165         .minor          = D7S_MINOR,
 166         .name           = DRIVER_NAME,
 167         .fops           = &d7s_fops
 168 };
 169
 170 static int d7s_probe(struct platform_device *op)
 171 {
 172         struct device_node *opts;
 173         int err = -EINVAL;
 174         struct d7s *p;
 175         u8 regs;
 176
 177         if (d7s_device)
 178                 goto out;
 179
 180         p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL);
 181         err = -ENOMEM;
 182         if (!p)
 183                 goto out;
 184
 185         p->regs = of_ioremap(&op->resource[0], 0, sizeof(u8), "d7s");
 186         if (!p->regs) {
 187                 printk(KERN_ERR PFX "Cannot map chip registers\n");
 188                 goto out;
 189         }
 190
 191         err = misc_register(&d7s_miscdev);
 192         if (err) {
 193                 printk(KERN_ERR PFX "Unable to acquire miscdevice minor %i\n",
 194                        D7S_MINOR);
 195                 goto out_iounmap;
 196         }
 197
 198         /* OBP option "d7s-flipped?" is honored as default for the
 199          * device, and reset default when detached
 200          */
 201         regs = readb(p->regs);
 202         opts = of_find_node_by_path("/options");
 203         if (opts)
 204             p->flipped = of_property_read_bool(opts, "d7s-flipped?");
 205
 206         if (p->flipped)
 207                 regs |= D7S_FLIP;
 208         else
 209                 regs &= ~D7S_FLIP;
 210
 211         writeb(regs,  p->regs);
 212
 213         printk(KERN_INFO PFX "7-Segment Display%pOF at [%s:0x%llx] %s\n",
 214                op->dev.of_node,
 215                (regs & D7S_FLIP) ? " (FLIPPED)" : "",
 216                op->resource[0].start,
 217                sol_compat ? "in sol_compat mode" : "");
 218
 219         dev_set_drvdata(&op->dev, p);
 220         d7s_device = p;
 221         err = 0;
 222         of_node_put(opts);
 223
 224 out:
 225         return err;
 226
 227 out_iounmap:
 228         of_iounmap(&op->resource[0], p->regs, sizeof(u8));
 229         goto out;
 230 }
 231
 232 static void d7s_remove(struct platform_device *op)
 233 {
 234         struct d7s *p = dev_get_drvdata(&op->dev);
 235         u8 regs = readb(p->regs);
 236
 237         /* Honor OBP d7s-flipped? unless operating in solaris-compat mode */
 238         if (sol_compat) {
 239                 if (p->flipped)
 240                         regs |= D7S_FLIP;
 241                 else
 242                         regs &= ~D7S_FLIP;
 243                 writeb(regs, p->regs);
 244         }
 245
 246         misc_deregister(&d7s_miscdev);
 247         of_iounmap(&op->resource[0], p->regs, sizeof(u8));
 248 }
 249
 250 static const struct of_device_id d7s_match[] = {
 251         {
 252                 .name = "display7seg",
 253         },
 254         {},
 255 };
 256 MODULE_DEVICE_TABLE(of, d7s_match);
 257
 258 static struct platform_driver d7s_driver = {
 259         .driver = {
 260                 .name = DRIVER_NAME,
 261                 .of_match_table = d7s_match,
 262         },
 263         .probe          = d7s_probe,
 264         .remove_new     = d7s_remove,
 265 };
 266
 267 module_platform_driver(d7s_driver);