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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 <asm/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_struct * volatile bfin_jc_tty; |
66 | static unsigned long bfin_jc_count; |
67 | static DEFINE_MUTEX(bfin_jc_tty_mutex); |
68 | static volatile struct circ_buf bfin_jc_write_buf; |
69 | |
70 | static int |
71 | bfin_jc_emudat_manager(void *arg) |
72 | { |
73 | uint32_t inbound_len = 0, outbound_len = 0; |
74 | |
75 | while (!kthread_should_stop()) { |
76 | /* no one left to give data to, so sleep */ |
77 | if (bfin_jc_tty == NULL && circ_empty(&bfin_jc_write_buf)) { |
78 | pr_debug("waiting for readers\n"); |
79 | __set_current_state(TASK_UNINTERRUPTIBLE); |
80 | schedule(); |
81 | __set_current_state(TASK_RUNNING); |
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 | if (inbound_len) |
89 | schedule(); |
90 | else |
91 | schedule_timeout_interruptible(HZ); |
92 | continue; |
93 | } |
94 | |
95 | /* if incoming data is ready, eat it */ |
96 | if (bfin_read_DBGSTAT() & EMUDIF) { |
97 | struct tty_struct *tty; |
98 | mutex_lock(&bfin_jc_tty_mutex); |
99 | tty = (struct tty_struct *)bfin_jc_tty; |
100 | if (tty != NULL) { |
101 | uint32_t emudat = bfin_read_emudat(); |
102 | if (inbound_len == 0) { |
103 | pr_debug("incoming length: 0x%08x\n", emudat); |
104 | inbound_len = emudat; |
105 | } else { |
106 | size_t num_chars = (4 <= inbound_len ? 4 : inbound_len); |
107 | pr_debug(" incoming data: 0x%08x (pushing %zu)\n", emudat, num_chars); |
108 | inbound_len -= num_chars; |
109 | tty_insert_flip_string(tty, (unsigned char *)&emudat, num_chars); |
110 | tty_flip_buffer_push(tty); |
111 | } |
112 | } |
113 | mutex_unlock(&bfin_jc_tty_mutex); |
114 | } |
115 | |
116 | /* if outgoing data is ready, post it */ |
117 | if (!(bfin_read_DBGSTAT() & EMUDOF) && !circ_empty(&bfin_jc_write_buf)) { |
118 | if (outbound_len == 0) { |
119 | outbound_len = circ_cnt(&bfin_jc_write_buf); |
120 | bfin_write_emudat(outbound_len); |
121 | pr_debug("outgoing length: 0x%08x\n", outbound_len); |
122 | } else { |
123 | struct tty_struct *tty; |
124 | int tail = bfin_jc_write_buf.tail; |
125 | size_t ate = (4 <= outbound_len ? 4 : outbound_len); |
126 | uint32_t emudat = |
127 | bfin_write_emudat_chars( |
128 | circ_byte(&bfin_jc_write_buf, tail + 0), |
129 | circ_byte(&bfin_jc_write_buf, tail + 1), |
130 | circ_byte(&bfin_jc_write_buf, tail + 2), |
131 | circ_byte(&bfin_jc_write_buf, tail + 3) |
132 | ); |
133 | bfin_jc_write_buf.tail += ate; |
134 | outbound_len -= ate; |
135 | mutex_lock(&bfin_jc_tty_mutex); |
136 | tty = (struct tty_struct *)bfin_jc_tty; |
137 | if (tty) |
138 | tty_wakeup(tty); |
139 | mutex_unlock(&bfin_jc_tty_mutex); |
140 | pr_debug(" outgoing data: 0x%08x (pushing %zu)\n", emudat, ate); |
141 | } |
142 | } |
143 | } |
144 | |
145 | __set_current_state(TASK_RUNNING); |
146 | return 0; |
147 | } |
148 | |
149 | static int |
150 | bfin_jc_open(struct tty_struct *tty, struct file *filp) |
151 | { |
152 | mutex_lock(&bfin_jc_tty_mutex); |
153 | pr_debug("open %lu\n", bfin_jc_count); |
154 | ++bfin_jc_count; |
155 | bfin_jc_tty = tty; |
156 | wake_up_process(bfin_jc_kthread); |
157 | mutex_unlock(&bfin_jc_tty_mutex); |
158 | return 0; |
159 | } |
160 | |
161 | static void |
162 | bfin_jc_close(struct tty_struct *tty, struct file *filp) |
163 | { |
164 | mutex_lock(&bfin_jc_tty_mutex); |
165 | pr_debug("close %lu\n", bfin_jc_count); |
166 | if (--bfin_jc_count == 0) |
167 | bfin_jc_tty = NULL; |
168 | wake_up_process(bfin_jc_kthread); |
169 | mutex_unlock(&bfin_jc_tty_mutex); |
170 | } |
171 | |
172 | /* XXX: we dont handle the put_char() case where we must handle count = 1 */ |
173 | static int |
174 | bfin_jc_circ_write(const unsigned char *buf, int count) |
175 | { |
176 | int i; |
177 | count = min(count, circ_free(&bfin_jc_write_buf)); |
178 | pr_debug("going to write chunk of %i bytes\n", count); |
179 | for (i = 0; i < count; ++i) |
180 | circ_byte(&bfin_jc_write_buf, bfin_jc_write_buf.head + i) = buf[i]; |
181 | bfin_jc_write_buf.head += i; |
182 | return i; |
183 | } |
184 | |
185 | #ifndef CONFIG_BFIN_JTAG_COMM_CONSOLE |
186 | # define acquire_console_sem() |
187 | # define release_console_sem() |
188 | #endif |
189 | static int |
190 | bfin_jc_write(struct tty_struct *tty, const unsigned char *buf, int count) |
191 | { |
192 | int i; |
193 | acquire_console_sem(); |
194 | i = bfin_jc_circ_write(buf, count); |
195 | release_console_sem(); |
196 | wake_up_process(bfin_jc_kthread); |
197 | return i; |
198 | } |
199 | |
200 | static void |
201 | bfin_jc_flush_chars(struct tty_struct *tty) |
202 | { |
203 | wake_up_process(bfin_jc_kthread); |
204 | } |
205 | |
206 | static int |
207 | bfin_jc_write_room(struct tty_struct *tty) |
208 | { |
209 | return circ_free(&bfin_jc_write_buf); |
210 | } |
211 | |
212 | static int |
213 | bfin_jc_chars_in_buffer(struct tty_struct *tty) |
214 | { |
215 | return circ_cnt(&bfin_jc_write_buf); |
216 | } |
217 | |
218 | static void |
219 | bfin_jc_wait_until_sent(struct tty_struct *tty, int timeout) |
220 | { |
221 | unsigned long expire = jiffies + timeout; |
222 | while (!circ_empty(&bfin_jc_write_buf)) { |
223 | if (signal_pending(current)) |
224 | break; |
225 | if (time_after(jiffies, expire)) |
226 | break; |
227 | } |
228 | } |
229 | |
230 | static const struct tty_operations bfin_jc_ops = { |
231 | .open = bfin_jc_open, |
232 | .close = bfin_jc_close, |
233 | .write = bfin_jc_write, |
234 | /*.put_char = bfin_jc_put_char,*/ |
235 | .flush_chars = bfin_jc_flush_chars, |
236 | .write_room = bfin_jc_write_room, |
237 | .chars_in_buffer = bfin_jc_chars_in_buffer, |
238 | .wait_until_sent = bfin_jc_wait_until_sent, |
239 | }; |
240 | |
241 | static int __init bfin_jc_init(void) |
242 | { |
243 | int ret; |
244 | |
245 | bfin_jc_kthread = kthread_create(bfin_jc_emudat_manager, NULL, DRV_NAME); |
246 | if (IS_ERR(bfin_jc_kthread)) |
247 | return PTR_ERR(bfin_jc_kthread); |
248 | |
249 | ret = -ENOMEM; |
250 | |
251 | bfin_jc_write_buf.head = bfin_jc_write_buf.tail = 0; |
252 | bfin_jc_write_buf.buf = kmalloc(CIRC_SIZE, GFP_KERNEL); |
253 | if (!bfin_jc_write_buf.buf) |
254 | goto err; |
255 | |
256 | bfin_jc_driver = alloc_tty_driver(1); |
257 | if (!bfin_jc_driver) |
258 | goto err; |
259 | |
260 | bfin_jc_driver->owner = THIS_MODULE; |
261 | bfin_jc_driver->driver_name = DRV_NAME; |
262 | bfin_jc_driver->name = DEV_NAME; |
263 | bfin_jc_driver->type = TTY_DRIVER_TYPE_SERIAL; |
264 | bfin_jc_driver->subtype = SERIAL_TYPE_NORMAL; |
265 | bfin_jc_driver->init_termios = tty_std_termios; |
266 | tty_set_operations(bfin_jc_driver, &bfin_jc_ops); |
267 | |
268 | ret = tty_register_driver(bfin_jc_driver); |
269 | if (ret) |
270 | goto err; |
271 | |
272 | pr_init(KERN_INFO DRV_NAME ": initialized\n"); |
273 | |
274 | return 0; |
275 | |
276 | err: |
277 | put_tty_driver(bfin_jc_driver); |
278 | kfree(bfin_jc_write_buf.buf); |
279 | kthread_stop(bfin_jc_kthread); |
280 | return ret; |
281 | } |
282 | module_init(bfin_jc_init); |
283 | |
284 | static void __exit bfin_jc_exit(void) |
285 | { |
286 | kthread_stop(bfin_jc_kthread); |
287 | kfree(bfin_jc_write_buf.buf); |
288 | tty_unregister_driver(bfin_jc_driver); |
289 | put_tty_driver(bfin_jc_driver); |
290 | } |
291 | module_exit(bfin_jc_exit); |
292 | |
293 | #if defined(CONFIG_BFIN_JTAG_COMM_CONSOLE) || defined(CONFIG_EARLY_PRINTK) |
294 | static void |
295 | bfin_jc_straight_buffer_write(const char *buf, unsigned count) |
296 | { |
297 | unsigned ate = 0; |
298 | while (bfin_read_DBGSTAT() & EMUDOF) |
299 | continue; |
300 | bfin_write_emudat(count); |
301 | while (ate < count) { |
302 | while (bfin_read_DBGSTAT() & EMUDOF) |
303 | continue; |
304 | bfin_write_emudat_chars(buf[ate], buf[ate+1], buf[ate+2], buf[ate+3]); |
305 | ate += 4; |
306 | } |
307 | } |
308 | #endif |
309 | |
310 | #ifdef CONFIG_BFIN_JTAG_COMM_CONSOLE |
311 | static void |
312 | bfin_jc_console_write(struct console *co, const char *buf, unsigned count) |
313 | { |
314 | if (bfin_jc_kthread == NULL) |
315 | bfin_jc_straight_buffer_write(buf, count); |
316 | else |
317 | bfin_jc_circ_write(buf, count); |
318 | } |
319 | |
320 | static struct tty_driver * |
321 | bfin_jc_console_device(struct console *co, int *index) |
322 | { |
323 | *index = co->index; |
324 | return bfin_jc_driver; |
325 | } |
326 | |
327 | static struct console bfin_jc_console = { |
328 | .name = DEV_NAME, |
329 | .write = bfin_jc_console_write, |
330 | .device = bfin_jc_console_device, |
331 | .flags = CON_ANYTIME | CON_PRINTBUFFER, |
332 | .index = -1, |
333 | }; |
334 | |
335 | static int __init bfin_jc_console_init(void) |
336 | { |
337 | register_console(&bfin_jc_console); |
338 | return 0; |
339 | } |
340 | console_initcall(bfin_jc_console_init); |
341 | #endif |
342 | |
343 | #ifdef CONFIG_EARLY_PRINTK |
344 | static void __init |
345 | bfin_jc_early_write(struct console *co, const char *buf, unsigned int count) |
346 | { |
347 | bfin_jc_straight_buffer_write(buf, count); |
348 | } |
349 | |
350 | static struct __initdata console bfin_jc_early_console = { |
351 | .name = "early_BFJC", |
352 | .write = bfin_jc_early_write, |
353 | .flags = CON_ANYTIME | CON_PRINTBUFFER, |
354 | .index = -1, |
355 | }; |
356 | |
357 | struct console * __init |
358 | bfin_jc_early_init(unsigned int port, unsigned int cflag) |
359 | { |
360 | return &bfin_jc_early_console; |
361 | } |
362 | #endif |
363 | |
364 | MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>"); |
365 | MODULE_DESCRIPTION("TTY over Blackfin JTAG Communication"); |
366 | MODULE_LICENSE("GPL"); |
367 |
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