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
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");
53
54struct d7s {
55	void __iomem	*regs;
56	bool		flipped;
57};
58struct 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 */
71static atomic_t d7s_users = ATOMIC_INIT(0);
72
73static 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
81static 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
102static 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
155static 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
164static struct miscdevice d7s_miscdev = {
165	.minor		= D7S_MINOR,
166	.name		= DRIVER_NAME,
167	.fops		= &d7s_fops
168};
169
170static 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
224out:
225	return err;
226
227out_iounmap:
228	of_iounmap(&op->resource[0], p->regs, sizeof(u8));
229	goto out;
230}
231
232static 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
250static const struct of_device_id d7s_match[] = {
251	{
252		.name = "display7seg",
253	},
254	{},
255};
256MODULE_DEVICE_TABLE(of, d7s_match);
257
258static 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
267module_platform_driver(d7s_driver);
268