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Linux/drivers/sbus/char/display7seg.c

  1 /* display7seg.c - Driver implementation for the 7-segment display
  2  *                 present on Sun Microsystems CP1400 and CP1500
  3  *
  4  * Copyright (c) 2000 Eric Brower (ebrower@usa.net)
  5  */
  6 
  7 #include <linux/kernel.h>
  8 #include <linux/module.h>
  9 #include <linux/fs.h>
 10 #include <linux/errno.h>
 11 #include <linux/major.h>
 12 #include <linux/miscdevice.h>
 13 #include <linux/ioport.h>               /* request_region */
 14 #include <linux/slab.h>
 15 #include <linux/mutex.h>
 16 #include <linux/of.h>
 17 #include <linux/of_device.h>
 18 #include <linux/atomic.h>
 19 #include <asm/uaccess.h>                /* put_/get_user                        */
 20 #include <asm/io.h>
 21 
 22 #include <asm/display7seg.h>
 23 
 24 #define D7S_MINOR       193
 25 #define DRIVER_NAME     "d7s"
 26 #define PFX             DRIVER_NAME ": "
 27 
 28 static DEFINE_MUTEX(d7s_mutex);
 29 static int sol_compat = 0;              /* Solaris compatibility mode   */
 30 
 31 /* Solaris compatibility flag -
 32  * The Solaris implementation omits support for several
 33  * documented driver features (ref Sun doc 806-0180-03).  
 34  * By default, this module supports the documented driver 
 35  * abilities, rather than the Solaris implementation:
 36  *
 37  *      1) Device ALWAYS reverts to OBP-specified FLIPPED mode
 38  *         upon closure of device or module unload.
 39  *      2) Device ioctls D7SIOCRD/D7SIOCWR honor toggling of
 40  *         FLIP bit
 41  *
 42  * If you wish the device to operate as under Solaris,
 43  * omitting above features, set this parameter to non-zero.
 44  */
 45 module_param(sol_compat, int, 0);
 46 MODULE_PARM_DESC(sol_compat, 
 47                  "Disables documented functionality omitted from Solaris driver");
 48 
 49 MODULE_AUTHOR("Eric Brower <ebrower@usa.net>");
 50 MODULE_DESCRIPTION("7-Segment Display driver for Sun Microsystems CP1400/1500");
 51 MODULE_LICENSE("GPL");
 52 MODULE_SUPPORTED_DEVICE("d7s");
 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                 if (regs & D7S_FLIP)
147                         regs &= ~D7S_FLIP;
148                 else
149                         regs |= D7S_FLIP;
150                 writeb(regs, p->regs);
151                 break;
152         }
153         mutex_unlock(&d7s_mutex);
154 
155         return error;
156 }
157 
158 static const struct file_operations d7s_fops = {
159         .owner =                THIS_MODULE,
160         .unlocked_ioctl =       d7s_ioctl,
161         .compat_ioctl =         d7s_ioctl,
162         .open =                 d7s_open,
163         .release =              d7s_release,
164         .llseek = noop_llseek,
165 };
166 
167 static struct miscdevice d7s_miscdev = {
168         .minor          = D7S_MINOR,
169         .name           = DRIVER_NAME,
170         .fops           = &d7s_fops
171 };
172 
173 static int d7s_probe(struct platform_device *op)
174 {
175         struct device_node *opts;
176         int err = -EINVAL;
177         struct d7s *p;
178         u8 regs;
179 
180         if (d7s_device)
181                 goto out;
182 
183         p = kzalloc(sizeof(*p), GFP_KERNEL);
184         err = -ENOMEM;
185         if (!p)
186                 goto out;
187 
188         p->regs = of_ioremap(&op->resource[0], 0, sizeof(u8), "d7s");
189         if (!p->regs) {
190                 printk(KERN_ERR PFX "Cannot map chip registers\n");
191                 goto out_free;
192         }
193 
194         err = misc_register(&d7s_miscdev);
195         if (err) {
196                 printk(KERN_ERR PFX "Unable to acquire miscdevice minor %i\n",
197                        D7S_MINOR);
198                 goto out_iounmap;
199         }
200 
201         /* OBP option "d7s-flipped?" is honored as default for the
202          * device, and reset default when detached
203          */
204         regs = readb(p->regs);
205         opts = of_find_node_by_path("/options");
206         if (opts &&
207             of_get_property(opts, "d7s-flipped?", NULL))
208                 p->flipped = true;
209 
210         if (p->flipped)
211                 regs |= D7S_FLIP;
212         else
213                 regs &= ~D7S_FLIP;
214 
215         writeb(regs,  p->regs);
216 
217         printk(KERN_INFO PFX "7-Segment Display%s at [%s:0x%llx] %s\n",
218                op->dev.of_node->full_name,
219                (regs & D7S_FLIP) ? " (FLIPPED)" : "",
220                op->resource[0].start,
221                sol_compat ? "in sol_compat mode" : "");
222 
223         dev_set_drvdata(&op->dev, p);
224         d7s_device = p;
225         err = 0;
226 
227 out:
228         return err;
229 
230 out_iounmap:
231         of_iounmap(&op->resource[0], p->regs, sizeof(u8));
232 
233 out_free:
234         kfree(p);
235         goto out;
236 }
237 
238 static int d7s_remove(struct platform_device *op)
239 {
240         struct d7s *p = dev_get_drvdata(&op->dev);
241         u8 regs = readb(p->regs);
242 
243         /* Honor OBP d7s-flipped? unless operating in solaris-compat mode */
244         if (sol_compat) {
245                 if (p->flipped)
246                         regs |= D7S_FLIP;
247                 else
248                         regs &= ~D7S_FLIP;
249                 writeb(regs, p->regs);
250         }
251 
252         misc_deregister(&d7s_miscdev);
253         of_iounmap(&op->resource[0], p->regs, sizeof(u8));
254         kfree(p);
255 
256         return 0;
257 }
258 
259 static const struct of_device_id d7s_match[] = {
260         {
261                 .name = "display7seg",
262         },
263         {},
264 };
265 MODULE_DEVICE_TABLE(of, d7s_match);
266 
267 static struct platform_driver d7s_driver = {
268         .driver = {
269                 .name = DRIVER_NAME,
270                 .owner = THIS_MODULE,
271                 .of_match_table = d7s_match,
272         },
273         .probe          = d7s_probe,
274         .remove         = d7s_remove,
275 };
276 
277 module_platform_driver(d7s_driver);
278 

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