1 /*
2 * linux/arch/alpha/kernel/srmcons.c
3 *
4 * Callback based driver for SRM Console console device.
5 * (TTY driver and console driver)
6 */
7
8 #include <linux/kernel.h>
9 #include <linux/init.h>
10 #include <linux/console.h>
11 #include <linux/delay.h>
12 #include <linux/mm.h>
13 #include <linux/slab.h>
14 #include <linux/spinlock.h>
15 #include <linux/timer.h>
16 #include <linux/tty.h>
17 #include <linux/tty_driver.h>
18 #include <linux/tty_flip.h>
19
20 #include <asm/console.h>
21 #include <asm/uaccess.h>
22
23
24 static DEFINE_SPINLOCK(srmcons_callback_lock);
25 static int srm_is_registered_console = 0;
26
27 /*
28 * The TTY driver
29 */
30 #define MAX_SRM_CONSOLE_DEVICES 1 /* only support 1 console device */
31
32 struct srmcons_private {
33 struct tty_port port;
34 struct timer_list timer;
35 } srmcons_singleton;
36
37 typedef union _srmcons_result {
38 struct {
39 unsigned long c :61;
40 unsigned long status :3;
41 } bits;
42 long as_long;
43 } srmcons_result;
44
45 /* called with callback_lock held */
46 static int
srmcons_do_receive_chars(struct tty_port * port)47 srmcons_do_receive_chars(struct tty_port *port)
48 {
49 srmcons_result result;
50 int count = 0, loops = 0;
51
52 do {
53 result.as_long = callback_getc(0);
54 if (result.bits.status < 2) {
55 tty_insert_flip_char(port, (char)result.bits.c, 0);
56 count++;
57 }
58 } while((result.bits.status & 1) && (++loops < 10));
59
60 if (count)
61 tty_schedule_flip(port);
62
63 return count;
64 }
65
66 static void
srmcons_receive_chars(unsigned long data)67 srmcons_receive_chars(unsigned long data)
68 {
69 struct srmcons_private *srmconsp = (struct srmcons_private *)data;
70 struct tty_port *port = &srmconsp->port;
71 unsigned long flags;
72 int incr = 10;
73
74 local_irq_save(flags);
75 if (spin_trylock(&srmcons_callback_lock)) {
76 if (!srmcons_do_receive_chars(port))
77 incr = 100;
78 spin_unlock(&srmcons_callback_lock);
79 }
80
81 spin_lock(&port->lock);
82 if (port->tty)
83 mod_timer(&srmconsp->timer, jiffies + incr);
84 spin_unlock(&port->lock);
85
86 local_irq_restore(flags);
87 }
88
89 /* called with callback_lock held */
90 static int
srmcons_do_write(struct tty_port * port,const char * buf,int count)91 srmcons_do_write(struct tty_port *port, const char *buf, int count)
92 {
93 static char str_cr[1] = "\r";
94 long c, remaining = count;
95 srmcons_result result;
96 char *cur;
97 int need_cr;
98
99 for (cur = (char *)buf; remaining > 0; ) {
100 need_cr = 0;
101 /*
102 * Break it up into reasonable size chunks to allow a chance
103 * for input to get in
104 */
105 for (c = 0; c < min_t(long, 128L, remaining) && !need_cr; c++)
106 if (cur[c] == '\n')
107 need_cr = 1;
108
109 while (c > 0) {
110 result.as_long = callback_puts(0, cur, c);
111 c -= result.bits.c;
112 remaining -= result.bits.c;
113 cur += result.bits.c;
114
115 /*
116 * Check for pending input iff a tty port was provided
117 */
118 if (port)
119 srmcons_do_receive_chars(port);
120 }
121
122 while (need_cr) {
123 result.as_long = callback_puts(0, str_cr, 1);
124 if (result.bits.c > 0)
125 need_cr = 0;
126 }
127 }
128 return count;
129 }
130
131 static int
srmcons_write(struct tty_struct * tty,const unsigned char * buf,int count)132 srmcons_write(struct tty_struct *tty,
133 const unsigned char *buf, int count)
134 {
135 unsigned long flags;
136
137 spin_lock_irqsave(&srmcons_callback_lock, flags);
138 srmcons_do_write(tty->port, (const char *) buf, count);
139 spin_unlock_irqrestore(&srmcons_callback_lock, flags);
140
141 return count;
142 }
143
144 static int
srmcons_write_room(struct tty_struct * tty)145 srmcons_write_room(struct tty_struct *tty)
146 {
147 return 512;
148 }
149
150 static int
srmcons_chars_in_buffer(struct tty_struct * tty)151 srmcons_chars_in_buffer(struct tty_struct *tty)
152 {
153 return 0;
154 }
155
156 static int
srmcons_open(struct tty_struct * tty,struct file * filp)157 srmcons_open(struct tty_struct *tty, struct file *filp)
158 {
159 struct srmcons_private *srmconsp = &srmcons_singleton;
160 struct tty_port *port = &srmconsp->port;
161 unsigned long flags;
162
163 spin_lock_irqsave(&port->lock, flags);
164
165 if (!port->tty) {
166 tty->driver_data = srmconsp;
167 tty->port = port;
168 port->tty = tty; /* XXX proper refcounting */
169 mod_timer(&srmconsp->timer, jiffies + 10);
170 }
171
172 spin_unlock_irqrestore(&port->lock, flags);
173
174 return 0;
175 }
176
177 static void
srmcons_close(struct tty_struct * tty,struct file * filp)178 srmcons_close(struct tty_struct *tty, struct file *filp)
179 {
180 struct srmcons_private *srmconsp = tty->driver_data;
181 struct tty_port *port = &srmconsp->port;
182 unsigned long flags;
183
184 spin_lock_irqsave(&port->lock, flags);
185
186 if (tty->count == 1) {
187 port->tty = NULL;
188 del_timer(&srmconsp->timer);
189 }
190
191 spin_unlock_irqrestore(&port->lock, flags);
192 }
193
194
195 static struct tty_driver *srmcons_driver;
196
197 static const struct tty_operations srmcons_ops = {
198 .open = srmcons_open,
199 .close = srmcons_close,
200 .write = srmcons_write,
201 .write_room = srmcons_write_room,
202 .chars_in_buffer= srmcons_chars_in_buffer,
203 };
204
205 static int __init
srmcons_init(void)206 srmcons_init(void)
207 {
208 setup_timer(&srmcons_singleton.timer, srmcons_receive_chars,
209 (unsigned long)&srmcons_singleton);
210 if (srm_is_registered_console) {
211 struct tty_driver *driver;
212 int err;
213
214 driver = alloc_tty_driver(MAX_SRM_CONSOLE_DEVICES);
215 if (!driver)
216 return -ENOMEM;
217
218 tty_port_init(&srmcons_singleton.port);
219
220 driver->driver_name = "srm";
221 driver->name = "srm";
222 driver->major = 0; /* dynamic */
223 driver->minor_start = 0;
224 driver->type = TTY_DRIVER_TYPE_SYSTEM;
225 driver->subtype = SYSTEM_TYPE_SYSCONS;
226 driver->init_termios = tty_std_termios;
227 tty_set_operations(driver, &srmcons_ops);
228 tty_port_link_device(&srmcons_singleton.port, driver, 0);
229 err = tty_register_driver(driver);
230 if (err) {
231 put_tty_driver(driver);
232 tty_port_destroy(&srmcons_singleton.port);
233 return err;
234 }
235 srmcons_driver = driver;
236 }
237
238 return -ENODEV;
239 }
240 device_initcall(srmcons_init);
241
242
243 /*
244 * The console driver
245 */
246 static void
srm_console_write(struct console * co,const char * s,unsigned count)247 srm_console_write(struct console *co, const char *s, unsigned count)
248 {
249 unsigned long flags;
250
251 spin_lock_irqsave(&srmcons_callback_lock, flags);
252 srmcons_do_write(NULL, s, count);
253 spin_unlock_irqrestore(&srmcons_callback_lock, flags);
254 }
255
256 static struct tty_driver *
srm_console_device(struct console * co,int * index)257 srm_console_device(struct console *co, int *index)
258 {
259 *index = co->index;
260 return srmcons_driver;
261 }
262
263 static int
srm_console_setup(struct console * co,char * options)264 srm_console_setup(struct console *co, char *options)
265 {
266 return 0;
267 }
268
269 static struct console srmcons = {
270 .name = "srm",
271 .write = srm_console_write,
272 .device = srm_console_device,
273 .setup = srm_console_setup,
274 .flags = CON_PRINTBUFFER | CON_BOOT,
275 .index = -1,
276 };
277
278 void __init
register_srm_console(void)279 register_srm_console(void)
280 {
281 if (!srm_is_registered_console) {
282 callback_open_console();
283 register_console(&srmcons);
284 srm_is_registered_console = 1;
285 }
286 }
287
288 void __init
unregister_srm_console(void)289 unregister_srm_console(void)
290 {
291 if (srm_is_registered_console) {
292 callback_close_console();
293 unregister_console(&srmcons);
294 srm_is_registered_console = 0;
295 }
296 }
297