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/device.h>
8#include <linux/kernel.h>
9#include <linux/module.h>
10#include <linux/fs.h>
11#include <linux/errno.h>
12#include <linux/major.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
29static DEFINE_MUTEX(d7s_mutex);
30static 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 */
46module_param(sol_compat, int, 0);
47MODULE_PARM_DESC(sol_compat,
48		 "Disables documented functionality omitted from Solaris driver");
49
50MODULE_AUTHOR("Eric Brower <ebrower@usa.net>");
51MODULE_DESCRIPTION("7-Segment Display driver for Sun Microsystems CP1400/1500");
52MODULE_LICENSE("GPL");
53MODULE_SUPPORTED_DEVICE("d7s");
54
55struct d7s {
56	void __iomem	*regs;
57	bool		flipped;
58};
59struct 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 */
72static atomic_t d7s_users = ATOMIC_INIT(0);
73
74static 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
82static 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
103static 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
156static const struct file_operations d7s_fops = {
157	.owner =		THIS_MODULE,
158	.unlocked_ioctl =	d7s_ioctl,
159	.compat_ioctl =		d7s_ioctl,
160	.open =			d7s_open,
161	.release =		d7s_release,
162	.llseek = noop_llseek,
163};
164
165static struct miscdevice d7s_miscdev = {
166	.minor		= D7S_MINOR,
167	.name		= DRIVER_NAME,
168	.fops		= &d7s_fops
169};
170
171static 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%s at [%s:0x%llx] %s\n",
216	       op->dev.of_node->full_name,
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
225out:
226	return err;
227
228out_iounmap:
229	of_iounmap(&op->resource[0], p->regs, sizeof(u8));
230
231out_free:
232	goto out;
233}
234
235static int d7s_remove(struct platform_device *op)
236{
237	struct d7s *p = dev_get_drvdata(&op->dev);
238	u8 regs = readb(p->regs);
239
240	/* Honor OBP d7s-flipped? unless operating in solaris-compat mode */
241	if (sol_compat) {
242		if (p->flipped)
243			regs |= D7S_FLIP;
244		else
245			regs &= ~D7S_FLIP;
246		writeb(regs, p->regs);
247	}
248
249	misc_deregister(&d7s_miscdev);
250	of_iounmap(&op->resource[0], p->regs, sizeof(u8));
251
252	return 0;
253}
254
255static const struct of_device_id d7s_match[] = {
256	{
257		.name = "display7seg",
258	},
259	{},
260};
261MODULE_DEVICE_TABLE(of, d7s_match);
262
263static struct platform_driver d7s_driver = {
264	.driver = {
265		.name = DRIVER_NAME,
266		.of_match_table = d7s_match,
267	},
268	.probe		= d7s_probe,
269	.remove		= d7s_remove,
270};
271
272module_platform_driver(d7s_driver);
273