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/of_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 MODULE_SUPPORTED_DEVICE("d7s");
54
55 struct d7s {
56 void __iomem *regs;
57 bool flipped;
58 };
59 struct d7s *d7s_device;
60
61 /*
62 * Register block address- see header for details
63 * -----------------------------------------
64 * | DP | ALARM | FLIP | 4 | 3 | 2 | 1 | 0 |
65 * -----------------------------------------
66 *
67 * DP - Toggles decimal point on/off
68 * ALARM - Toggles "Alarm" LED green/red
69 * FLIP - Inverts display for upside-down mounted board
70 * bits 0-4 - 7-segment display contents
71 */
72 static atomic_t d7s_users = ATOMIC_INIT(0);
73
d7s_open(struct inode * inode,struct file * f)74 static int d7s_open(struct inode *inode, struct file *f)
75 {
76 if (D7S_MINOR != iminor(inode))
77 return -ENODEV;
78 atomic_inc(&d7s_users);
79 return 0;
80 }
81
d7s_release(struct inode * inode,struct file * f)82 static int d7s_release(struct inode *inode, struct file *f)
83 {
84 /* Reset flipped state to OBP default only if
85 * no other users have the device open and we
86 * are not operating in solaris-compat mode
87 */
88 if (atomic_dec_and_test(&d7s_users) && !sol_compat) {
89 struct d7s *p = d7s_device;
90 u8 regval = 0;
91
92 regval = readb(p->regs);
93 if (p->flipped)
94 regval |= D7S_FLIP;
95 else
96 regval &= ~D7S_FLIP;
97 writeb(regval, p->regs);
98 }
99
100 return 0;
101 }
102
d7s_ioctl(struct file * file,unsigned int cmd,unsigned long arg)103 static long d7s_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
104 {
105 struct d7s *p = d7s_device;
106 u8 regs = readb(p->regs);
107 int error = 0;
108 u8 ireg = 0;
109
110 if (D7S_MINOR != iminor(file_inode(file)))
111 return -ENODEV;
112
113 mutex_lock(&d7s_mutex);
114 switch (cmd) {
115 case D7SIOCWR:
116 /* assign device register values we mask-out D7S_FLIP
117 * if in sol_compat mode
118 */
119 if (get_user(ireg, (int __user *) arg)) {
120 error = -EFAULT;
121 break;
122 }
123 if (sol_compat) {
124 if (regs & D7S_FLIP)
125 ireg |= D7S_FLIP;
126 else
127 ireg &= ~D7S_FLIP;
128 }
129 writeb(ireg, p->regs);
130 break;
131
132 case D7SIOCRD:
133 /* retrieve device register values
134 * NOTE: Solaris implementation returns D7S_FLIP bit
135 * as toggled by user, even though it does not honor it.
136 * This driver will not misinform you about the state
137 * of your hardware while in sol_compat mode
138 */
139 if (put_user(regs, (int __user *) arg)) {
140 error = -EFAULT;
141 break;
142 }
143 break;
144
145 case D7SIOCTM:
146 /* toggle device mode-- flip display orientation */
147 regs ^= D7S_FLIP;
148 writeb(regs, p->regs);
149 break;
150 }
151 mutex_unlock(&d7s_mutex);
152
153 return error;
154 }
155
156 static const struct file_operations d7s_fops = {
157 .owner = THIS_MODULE,
158 .unlocked_ioctl = d7s_ioctl,
159 .compat_ioctl = compat_ptr_ioctl,
160 .open = d7s_open,
161 .release = d7s_release,
162 .llseek = noop_llseek,
163 };
164
165 static struct miscdevice d7s_miscdev = {
166 .minor = D7S_MINOR,
167 .name = DRIVER_NAME,
168 .fops = &d7s_fops
169 };
170
d7s_probe(struct platform_device * op)171 static int d7s_probe(struct platform_device *op)
172 {
173 struct device_node *opts;
174 int err = -EINVAL;
175 struct d7s *p;
176 u8 regs;
177
178 if (d7s_device)
179 goto out;
180
181 p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL);
182 err = -ENOMEM;
183 if (!p)
184 goto out;
185
186 p->regs = of_ioremap(&op->resource[0], 0, sizeof(u8), "d7s");
187 if (!p->regs) {
188 printk(KERN_ERR PFX "Cannot map chip registers\n");
189 goto out_free;
190 }
191
192 err = misc_register(&d7s_miscdev);
193 if (err) {
194 printk(KERN_ERR PFX "Unable to acquire miscdevice minor %i\n",
195 D7S_MINOR);
196 goto out_iounmap;
197 }
198
199 /* OBP option "d7s-flipped?" is honored as default for the
200 * device, and reset default when detached
201 */
202 regs = readb(p->regs);
203 opts = of_find_node_by_path("/options");
204 if (opts &&
205 of_get_property(opts, "d7s-flipped?", NULL))
206 p->flipped = true;
207
208 if (p->flipped)
209 regs |= D7S_FLIP;
210 else
211 regs &= ~D7S_FLIP;
212
213 writeb(regs, p->regs);
214
215 printk(KERN_INFO PFX "7-Segment Display%pOF at [%s:0x%llx] %s\n",
216 op->dev.of_node,
217 (regs & D7S_FLIP) ? " (FLIPPED)" : "",
218 op->resource[0].start,
219 sol_compat ? "in sol_compat mode" : "");
220
221 dev_set_drvdata(&op->dev, p);
222 d7s_device = p;
223 err = 0;
224 of_node_put(opts);
225
226 out:
227 return err;
228
229 out_iounmap:
230 of_iounmap(&op->resource[0], p->regs, sizeof(u8));
231
232 out_free:
233 goto out;
234 }
235
d7s_remove(struct platform_device * op)236 static int d7s_remove(struct platform_device *op)
237 {
238 struct d7s *p = dev_get_drvdata(&op->dev);
239 u8 regs = readb(p->regs);
240
241 /* Honor OBP d7s-flipped? unless operating in solaris-compat mode */
242 if (sol_compat) {
243 if (p->flipped)
244 regs |= D7S_FLIP;
245 else
246 regs &= ~D7S_FLIP;
247 writeb(regs, p->regs);
248 }
249
250 misc_deregister(&d7s_miscdev);
251 of_iounmap(&op->resource[0], p->regs, sizeof(u8));
252
253 return 0;
254 }
255
256 static const struct of_device_id d7s_match[] = {
257 {
258 .name = "display7seg",
259 },
260 {},
261 };
262 MODULE_DEVICE_TABLE(of, d7s_match);
263
264 static struct platform_driver d7s_driver = {
265 .driver = {
266 .name = DRIVER_NAME,
267 .of_match_table = d7s_match,
268 },
269 .probe = d7s_probe,
270 .remove = d7s_remove,
271 };
272
273 module_platform_driver(d7s_driver);
274