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 
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 	    of_get_property(opts, "d7s-flipped?", NULL))
205 		p->flipped = true;
206 
207 	if (p->flipped)
208 		regs |= D7S_FLIP;
209 	else
210 		regs &= ~D7S_FLIP;
211 
212 	writeb(regs,  p->regs);
213 
214 	printk(KERN_INFO PFX "7-Segment Display%pOF at [%s:0x%llx] %s\n",
215 	       op->dev.of_node,
216 	       (regs & D7S_FLIP) ? " (FLIPPED)" : "",
217 	       op->resource[0].start,
218 	       sol_compat ? "in sol_compat mode" : "");
219 
220 	dev_set_drvdata(&op->dev, p);
221 	d7s_device = p;
222 	err = 0;
223 	of_node_put(opts);
224 
225 out:
226 	return err;
227 
228 out_iounmap:
229 	of_iounmap(&op->resource[0], p->regs, sizeof(u8));
230 	goto out;
231 }
232 
d7s_remove(struct platform_device * op)233 static int d7s_remove(struct platform_device *op)
234 {
235 	struct d7s *p = dev_get_drvdata(&op->dev);
236 	u8 regs = readb(p->regs);
237 
238 	/* Honor OBP d7s-flipped? unless operating in solaris-compat mode */
239 	if (sol_compat) {
240 		if (p->flipped)
241 			regs |= D7S_FLIP;
242 		else
243 			regs &= ~D7S_FLIP;
244 		writeb(regs, p->regs);
245 	}
246 
247 	misc_deregister(&d7s_miscdev);
248 	of_iounmap(&op->resource[0], p->regs, sizeof(u8));
249 
250 	return 0;
251 }
252 
253 static const struct of_device_id d7s_match[] = {
254 	{
255 		.name = "display7seg",
256 	},
257 	{},
258 };
259 MODULE_DEVICE_TABLE(of, d7s_match);
260 
261 static struct platform_driver d7s_driver = {
262 	.driver = {
263 		.name = DRIVER_NAME,
264 		.of_match_table = d7s_match,
265 	},
266 	.probe		= d7s_probe,
267 	.remove		= d7s_remove,
268 };
269 
270 module_platform_driver(d7s_driver);
271