serial: tegra: Fix stop_tx
[linux-3.10.git] / drivers / tty / bfin_jtag_comm.c
1 /*
2  * TTY over Blackfin JTAG Communication
3  *
4  * Copyright 2008-2009 Analog Devices Inc.
5  *
6  * Enter bugs at http://blackfin.uclinux.org/
7  *
8  * Licensed under the GPL-2 or later.
9  */
10
11 #define DRV_NAME "bfin-jtag-comm"
12 #define DEV_NAME "ttyBFJC"
13 #define pr_fmt(fmt) DRV_NAME ": " fmt
14
15 #include <linux/circ_buf.h>
16 #include <linux/console.h>
17 #include <linux/delay.h>
18 #include <linux/err.h>
19 #include <linux/kernel.h>
20 #include <linux/kthread.h>
21 #include <linux/module.h>
22 #include <linux/mutex.h>
23 #include <linux/sched.h>
24 #include <linux/slab.h>
25 #include <linux/tty.h>
26 #include <linux/tty_driver.h>
27 #include <linux/tty_flip.h>
28 #include <linux/atomic.h>
29
30 #define pr_init(fmt, args...) ({ static const __initconst char __fmt[] = fmt; printk(__fmt, ## args); })
31
32 /* See the Debug/Emulation chapter in the HRM */
33 #define EMUDOF   0x00000001     /* EMUDAT_OUT full & valid */
34 #define EMUDIF   0x00000002     /* EMUDAT_IN full & valid */
35 #define EMUDOOVF 0x00000004     /* EMUDAT_OUT overflow */
36 #define EMUDIOVF 0x00000008     /* EMUDAT_IN overflow */
37
38 static inline uint32_t bfin_write_emudat(uint32_t emudat)
39 {
40         __asm__ __volatile__("emudat = %0;" : : "d"(emudat));
41         return emudat;
42 }
43
44 static inline uint32_t bfin_read_emudat(void)
45 {
46         uint32_t emudat;
47         __asm__ __volatile__("%0 = emudat;" : "=d"(emudat));
48         return emudat;
49 }
50
51 static inline uint32_t bfin_write_emudat_chars(char a, char b, char c, char d)
52 {
53         return bfin_write_emudat((a << 0) | (b << 8) | (c << 16) | (d << 24));
54 }
55
56 #define CIRC_SIZE 2048  /* see comment in tty_io.c:do_tty_write() */
57 #define CIRC_MASK (CIRC_SIZE - 1)
58 #define circ_empty(circ)     ((circ)->head == (circ)->tail)
59 #define circ_free(circ)      CIRC_SPACE((circ)->head, (circ)->tail, CIRC_SIZE)
60 #define circ_cnt(circ)       CIRC_CNT((circ)->head, (circ)->tail, CIRC_SIZE)
61 #define circ_byte(circ, idx) ((circ)->buf[(idx) & CIRC_MASK])
62
63 static struct tty_driver *bfin_jc_driver;
64 static struct task_struct *bfin_jc_kthread;
65 static struct tty_port port;
66 static volatile struct circ_buf bfin_jc_write_buf;
67
68 static int
69 bfin_jc_emudat_manager(void *arg)
70 {
71         uint32_t inbound_len = 0, outbound_len = 0;
72
73         while (!kthread_should_stop()) {
74                 struct tty_struct *tty = tty_port_tty_get(&port);
75                 /* no one left to give data to, so sleep */
76                 if (tty == NULL && circ_empty(&bfin_jc_write_buf)) {
77                         pr_debug("waiting for readers\n");
78                         __set_current_state(TASK_UNINTERRUPTIBLE);
79                         schedule();
80                         __set_current_state(TASK_RUNNING);
81                         continue;
82                 }
83
84                 /* no data available, so just chill */
85                 if (!(bfin_read_DBGSTAT() & EMUDIF) && circ_empty(&bfin_jc_write_buf)) {
86                         pr_debug("waiting for data (in_len = %i) (circ: %i %i)\n",
87                                 inbound_len, bfin_jc_write_buf.tail, bfin_jc_write_buf.head);
88                         tty_kref_put(tty);
89                         if (inbound_len)
90                                 schedule();
91                         else
92                                 schedule_timeout_interruptible(HZ);
93                         continue;
94                 }
95
96                 /* if incoming data is ready, eat it */
97                 if (bfin_read_DBGSTAT() & EMUDIF) {
98                         uint32_t emudat = bfin_read_emudat();
99                         if (inbound_len == 0) {
100                                 pr_debug("incoming length: 0x%08x\n", emudat);
101                                 inbound_len = emudat;
102                         } else {
103                                 size_t num_chars = (4 <= inbound_len ? 4 : inbound_len);
104                                 pr_debug("  incoming data: 0x%08x (pushing %zu)\n", emudat, num_chars);
105                                 inbound_len -= num_chars;
106                                 tty_insert_flip_string(&port, (unsigned char *)&emudat, num_chars);
107                                 tty_flip_buffer_push(&port);
108                         }
109                 }
110
111                 /* if outgoing data is ready, post it */
112                 if (!(bfin_read_DBGSTAT() & EMUDOF) && !circ_empty(&bfin_jc_write_buf)) {
113                         if (outbound_len == 0) {
114                                 outbound_len = circ_cnt(&bfin_jc_write_buf);
115                                 bfin_write_emudat(outbound_len);
116                                 pr_debug("outgoing length: 0x%08x\n", outbound_len);
117                         } else {
118                                 int tail = bfin_jc_write_buf.tail;
119                                 size_t ate = (4 <= outbound_len ? 4 : outbound_len);
120                                 uint32_t emudat =
121                                 bfin_write_emudat_chars(
122                                         circ_byte(&bfin_jc_write_buf, tail + 0),
123                                         circ_byte(&bfin_jc_write_buf, tail + 1),
124                                         circ_byte(&bfin_jc_write_buf, tail + 2),
125                                         circ_byte(&bfin_jc_write_buf, tail + 3)
126                                 );
127                                 bfin_jc_write_buf.tail += ate;
128                                 outbound_len -= ate;
129                                 if (tty)
130                                         tty_wakeup(tty);
131                                 pr_debug("  outgoing data: 0x%08x (pushing %zu)\n", emudat, ate);
132                         }
133                 }
134                 tty_kref_put(tty);
135         }
136
137         __set_current_state(TASK_RUNNING);
138         return 0;
139 }
140
141 static int
142 bfin_jc_open(struct tty_struct *tty, struct file *filp)
143 {
144         unsigned long flags;
145
146         spin_lock_irqsave(&port.lock, flags);
147         port.count++;
148         spin_unlock_irqrestore(&port.lock, flags);
149         tty_port_tty_set(&port, tty);
150         wake_up_process(bfin_jc_kthread);
151         return 0;
152 }
153
154 static void
155 bfin_jc_close(struct tty_struct *tty, struct file *filp)
156 {
157         unsigned long flags;
158         bool last;
159
160         spin_lock_irqsave(&port.lock, flags);
161         last = --port.count == 0;
162         spin_unlock_irqrestore(&port.lock, flags);
163         if (last)
164                 tty_port_tty_set(&port, NULL);
165         wake_up_process(bfin_jc_kthread);
166 }
167
168 /* XXX: we dont handle the put_char() case where we must handle count = 1 */
169 static int
170 bfin_jc_circ_write(const unsigned char *buf, int count)
171 {
172         int i;
173         count = min(count, circ_free(&bfin_jc_write_buf));
174         pr_debug("going to write chunk of %i bytes\n", count);
175         for (i = 0; i < count; ++i)
176                 circ_byte(&bfin_jc_write_buf, bfin_jc_write_buf.head + i) = buf[i];
177         bfin_jc_write_buf.head += i;
178         return i;
179 }
180
181 #ifndef CONFIG_BFIN_JTAG_COMM_CONSOLE
182 # define console_lock()
183 # define console_unlock()
184 #endif
185 static int
186 bfin_jc_write(struct tty_struct *tty, const unsigned char *buf, int count)
187 {
188         int i;
189         console_lock();
190         i = bfin_jc_circ_write(buf, count);
191         console_unlock();
192         wake_up_process(bfin_jc_kthread);
193         return i;
194 }
195
196 static void
197 bfin_jc_flush_chars(struct tty_struct *tty)
198 {
199         wake_up_process(bfin_jc_kthread);
200 }
201
202 static int
203 bfin_jc_write_room(struct tty_struct *tty)
204 {
205         return circ_free(&bfin_jc_write_buf);
206 }
207
208 static int
209 bfin_jc_chars_in_buffer(struct tty_struct *tty)
210 {
211         return circ_cnt(&bfin_jc_write_buf);
212 }
213
214 static void
215 bfin_jc_wait_until_sent(struct tty_struct *tty, int timeout)
216 {
217         unsigned long expire = jiffies + timeout;
218         while (!circ_empty(&bfin_jc_write_buf)) {
219                 if (signal_pending(current))
220                         break;
221                 if (time_after(jiffies, expire))
222                         break;
223         }
224 }
225
226 static const struct tty_operations bfin_jc_ops = {
227         .open            = bfin_jc_open,
228         .close           = bfin_jc_close,
229         .write           = bfin_jc_write,
230         /*.put_char        = bfin_jc_put_char,*/
231         .flush_chars     = bfin_jc_flush_chars,
232         .write_room      = bfin_jc_write_room,
233         .chars_in_buffer = bfin_jc_chars_in_buffer,
234         .wait_until_sent = bfin_jc_wait_until_sent,
235 };
236
237 static int __init bfin_jc_init(void)
238 {
239         int ret;
240
241         bfin_jc_kthread = kthread_create(bfin_jc_emudat_manager, NULL, DRV_NAME);
242         if (IS_ERR(bfin_jc_kthread))
243                 return PTR_ERR(bfin_jc_kthread);
244
245         ret = -ENOMEM;
246
247         bfin_jc_write_buf.head = bfin_jc_write_buf.tail = 0;
248         bfin_jc_write_buf.buf = kmalloc(CIRC_SIZE, GFP_KERNEL);
249         if (!bfin_jc_write_buf.buf)
250                 goto err_buf;
251
252         bfin_jc_driver = alloc_tty_driver(1);
253         if (!bfin_jc_driver)
254                 goto err_driver;
255
256         tty_port_init(&port);
257
258         bfin_jc_driver->driver_name  = DRV_NAME;
259         bfin_jc_driver->name         = DEV_NAME;
260         bfin_jc_driver->type         = TTY_DRIVER_TYPE_SERIAL;
261         bfin_jc_driver->subtype      = SERIAL_TYPE_NORMAL;
262         bfin_jc_driver->init_termios = tty_std_termios;
263         tty_set_operations(bfin_jc_driver, &bfin_jc_ops);
264         tty_port_link_device(&port, bfin_jc_driver, 0);
265
266         ret = tty_register_driver(bfin_jc_driver);
267         if (ret)
268                 goto err;
269
270         pr_init(KERN_INFO DRV_NAME ": initialized\n");
271
272         return 0;
273
274  err:
275         tty_port_destroy(&port);
276         put_tty_driver(bfin_jc_driver);
277  err_driver:
278         kfree(bfin_jc_write_buf.buf);
279  err_buf:
280         kthread_stop(bfin_jc_kthread);
281         return ret;
282 }
283 module_init(bfin_jc_init);
284
285 static void __exit bfin_jc_exit(void)
286 {
287         kthread_stop(bfin_jc_kthread);
288         kfree(bfin_jc_write_buf.buf);
289         tty_unregister_driver(bfin_jc_driver);
290         put_tty_driver(bfin_jc_driver);
291         tty_port_destroy(&port);
292 }
293 module_exit(bfin_jc_exit);
294
295 #if defined(CONFIG_BFIN_JTAG_COMM_CONSOLE) || defined(CONFIG_EARLY_PRINTK)
296 static void
297 bfin_jc_straight_buffer_write(const char *buf, unsigned count)
298 {
299         unsigned ate = 0;
300         while (bfin_read_DBGSTAT() & EMUDOF)
301                 continue;
302         bfin_write_emudat(count);
303         while (ate < count) {
304                 while (bfin_read_DBGSTAT() & EMUDOF)
305                         continue;
306                 bfin_write_emudat_chars(buf[ate], buf[ate+1], buf[ate+2], buf[ate+3]);
307                 ate += 4;
308         }
309 }
310 #endif
311
312 #ifdef CONFIG_BFIN_JTAG_COMM_CONSOLE
313 static void
314 bfin_jc_console_write(struct console *co, const char *buf, unsigned count)
315 {
316         if (bfin_jc_kthread == NULL)
317                 bfin_jc_straight_buffer_write(buf, count);
318         else
319                 bfin_jc_circ_write(buf, count);
320 }
321
322 static struct tty_driver *
323 bfin_jc_console_device(struct console *co, int *index)
324 {
325         *index = co->index;
326         return bfin_jc_driver;
327 }
328
329 static struct console bfin_jc_console = {
330         .name    = DEV_NAME,
331         .write   = bfin_jc_console_write,
332         .device  = bfin_jc_console_device,
333         .flags   = CON_ANYTIME | CON_PRINTBUFFER,
334         .index   = -1,
335 };
336
337 static int __init bfin_jc_console_init(void)
338 {
339         register_console(&bfin_jc_console);
340         return 0;
341 }
342 console_initcall(bfin_jc_console_init);
343 #endif
344
345 #ifdef CONFIG_EARLY_PRINTK
346 static void __init
347 bfin_jc_early_write(struct console *co, const char *buf, unsigned int count)
348 {
349         bfin_jc_straight_buffer_write(buf, count);
350 }
351
352 static struct __initdata console bfin_jc_early_console = {
353         .name   = "early_BFJC",
354         .write   = bfin_jc_early_write,
355         .flags   = CON_ANYTIME | CON_PRINTBUFFER,
356         .index   = -1,
357 };
358
359 struct console * __init
360 bfin_jc_early_init(unsigned int port, unsigned int cflag)
361 {
362         return &bfin_jc_early_console;
363 }
364 #endif
365
366 MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
367 MODULE_DESCRIPTION("TTY over Blackfin JTAG Communication");
368 MODULE_LICENSE("GPL");