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 | |
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 | |
73 | static int d7s_open(struct inode *inode, struct file *f) |
74 | { |
75 | if (D7S_MINOR != iminor(inode)) |
76 | return -ENODEV; |
77 | atomic_inc(v: &d7s_users); |
78 | return 0; |
79 | } |
80 | |
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(v: &d7s_users) && !sol_compat) { |
88 | struct d7s *p = d7s_device; |
89 | u8 regval = 0; |
90 | |
91 | regval = readb(addr: p->regs); |
92 | if (p->flipped) |
93 | regval |= D7S_FLIP; |
94 | else |
95 | regval &= ~D7S_FLIP; |
96 | writeb(val: regval, addr: p->regs); |
97 | } |
98 | |
99 | return 0; |
100 | } |
101 | |
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(addr: p->regs); |
106 | int error = 0; |
107 | u8 ireg = 0; |
108 | |
109 | if (D7S_MINOR != iminor(inode: file_inode(f: 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(val: ireg, addr: 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(val: regs, addr: p->regs); |
148 | break; |
149 | } |
150 | mutex_unlock(lock: &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 | |
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(dev: &op->dev, size: 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(misc: &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(addr: p->regs); |
202 | opts = of_find_node_by_path(path: "/options" ); |
203 | if (opts) |
204 | p->flipped = of_property_read_bool(np: opts, propname: "d7s-flipped?" ); |
205 | |
206 | if (p->flipped) |
207 | regs |= D7S_FLIP; |
208 | else |
209 | regs &= ~D7S_FLIP; |
210 | |
211 | writeb(val: regs, addr: 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(dev: &op->dev, data: p); |
220 | d7s_device = p; |
221 | err = 0; |
222 | of_node_put(node: opts); |
223 | |
224 | out: |
225 | return err; |
226 | |
227 | out_iounmap: |
228 | of_iounmap(&op->resource[0], p->regs, sizeof(u8)); |
229 | goto out; |
230 | } |
231 | |
232 | static int d7s_remove(struct platform_device *op) |
233 | { |
234 | struct d7s *p = dev_get_drvdata(dev: &op->dev); |
235 | u8 regs = readb(addr: 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(val: regs, addr: p->regs); |
244 | } |
245 | |
246 | misc_deregister(misc: &d7s_miscdev); |
247 | of_iounmap(&op->resource[0], p->regs, sizeof(u8)); |
248 | |
249 | return 0; |
250 | } |
251 | |
252 | static const struct of_device_id d7s_match[] = { |
253 | { |
254 | .name = "display7seg" , |
255 | }, |
256 | {}, |
257 | }; |
258 | MODULE_DEVICE_TABLE(of, d7s_match); |
259 | |
260 | static struct platform_driver d7s_driver = { |
261 | .driver = { |
262 | .name = DRIVER_NAME, |
263 | .of_match_table = d7s_match, |
264 | }, |
265 | .probe = d7s_probe, |
266 | .remove = d7s_remove, |
267 | }; |
268 | |
269 | module_platform_driver(d7s_driver); |
270 | |