xref: /openbmc/linux/drivers/sbus/char/display7seg.c (revision 63dc02bd)
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/init.h>
13 #include <linux/miscdevice.h>
14 #include <linux/ioport.h>		/* request_region */
15 #include <linux/slab.h>
16 #include <linux/mutex.h>
17 #include <linux/of.h>
18 #include <linux/of_device.h>
19 #include <linux/atomic.h>
20 #include <asm/uaccess.h>		/* put_/get_user			*/
21 #include <asm/io.h>
22 
23 #include <asm/display7seg.h>
24 
25 #define D7S_MINOR	193
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 
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 
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 
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->f_path.dentry->d_inode))
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 		if (regs & D7S_FLIP)
148 			regs &= ~D7S_FLIP;
149 		else
150 			regs |= D7S_FLIP;
151 		writeb(regs, p->regs);
152 		break;
153 	};
154 	mutex_unlock(&d7s_mutex);
155 
156 	return error;
157 }
158 
159 static const struct file_operations d7s_fops = {
160 	.owner =		THIS_MODULE,
161 	.unlocked_ioctl =	d7s_ioctl,
162 	.compat_ioctl =		d7s_ioctl,
163 	.open =			d7s_open,
164 	.release =		d7s_release,
165 	.llseek = noop_llseek,
166 };
167 
168 static struct miscdevice d7s_miscdev = {
169 	.minor		= D7S_MINOR,
170 	.name		= DRIVER_NAME,
171 	.fops		= &d7s_fops
172 };
173 
174 static int __devinit d7s_probe(struct platform_device *op)
175 {
176 	struct device_node *opts;
177 	int err = -EINVAL;
178 	struct d7s *p;
179 	u8 regs;
180 
181 	if (d7s_device)
182 		goto out;
183 
184 	p = kzalloc(sizeof(*p), GFP_KERNEL);
185 	err = -ENOMEM;
186 	if (!p)
187 		goto out;
188 
189 	p->regs = of_ioremap(&op->resource[0], 0, sizeof(u8), "d7s");
190 	if (!p->regs) {
191 		printk(KERN_ERR PFX "Cannot map chip registers\n");
192 		goto out_free;
193 	}
194 
195 	err = misc_register(&d7s_miscdev);
196 	if (err) {
197 		printk(KERN_ERR PFX "Unable to acquire miscdevice minor %i\n",
198 		       D7S_MINOR);
199 		goto out_iounmap;
200 	}
201 
202 	/* OBP option "d7s-flipped?" is honored as default for the
203 	 * device, and reset default when detached
204 	 */
205 	regs = readb(p->regs);
206 	opts = of_find_node_by_path("/options");
207 	if (opts &&
208 	    of_get_property(opts, "d7s-flipped?", NULL))
209 		p->flipped = true;
210 
211 	if (p->flipped)
212 		regs |= D7S_FLIP;
213 	else
214 		regs &= ~D7S_FLIP;
215 
216 	writeb(regs,  p->regs);
217 
218 	printk(KERN_INFO PFX "7-Segment Display%s at [%s:0x%llx] %s\n",
219 	       op->dev.of_node->full_name,
220 	       (regs & D7S_FLIP) ? " (FLIPPED)" : "",
221 	       op->resource[0].start,
222 	       sol_compat ? "in sol_compat mode" : "");
223 
224 	dev_set_drvdata(&op->dev, p);
225 	d7s_device = p;
226 	err = 0;
227 
228 out:
229 	return err;
230 
231 out_iounmap:
232 	of_iounmap(&op->resource[0], p->regs, sizeof(u8));
233 
234 out_free:
235 	kfree(p);
236 	goto out;
237 }
238 
239 static int __devexit d7s_remove(struct platform_device *op)
240 {
241 	struct d7s *p = dev_get_drvdata(&op->dev);
242 	u8 regs = readb(p->regs);
243 
244 	/* Honor OBP d7s-flipped? unless operating in solaris-compat mode */
245 	if (sol_compat) {
246 		if (p->flipped)
247 			regs |= D7S_FLIP;
248 		else
249 			regs &= ~D7S_FLIP;
250 		writeb(regs, p->regs);
251 	}
252 
253 	misc_deregister(&d7s_miscdev);
254 	of_iounmap(&op->resource[0], p->regs, sizeof(u8));
255 	kfree(p);
256 
257 	return 0;
258 }
259 
260 static const struct of_device_id d7s_match[] = {
261 	{
262 		.name = "display7seg",
263 	},
264 	{},
265 };
266 MODULE_DEVICE_TABLE(of, d7s_match);
267 
268 static struct platform_driver d7s_driver = {
269 	.driver = {
270 		.name = DRIVER_NAME,
271 		.owner = THIS_MODULE,
272 		.of_match_table = d7s_match,
273 	},
274 	.probe		= d7s_probe,
275 	.remove		= __devexit_p(d7s_remove),
276 };
277 
278 module_platform_driver(d7s_driver);
279