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
d7s_open(struct inode * inode,struct file * f)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
d7s_release(struct inode * inode,struct file * f)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
d7s_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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
d7s_probe(struct platform_device * op)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
d7s_remove(struct platform_device * op)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);
268