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
bfin_write_emudat(uint32_t emudat)38 static inline uint32_t bfin_write_emudat(uint32_t emudat)
39 {
40 __asm__ __volatile__("emudat = %0;" : : "d"(emudat));
41 return emudat;
42 }
43
bfin_read_emudat(void)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
bfin_write_emudat_chars(char a,char b,char c,char d)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
bfin_jc_emudat_manager(void * arg)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
bfin_jc_open(struct tty_struct * tty,struct file * filp)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
bfin_jc_close(struct tty_struct * tty,struct file * filp)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
bfin_jc_circ_write(const unsigned char * buf,int count)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 console_lock()
187 # define console_unlock()
188 #endif
189 static int
bfin_jc_write(struct tty_struct * tty,const unsigned char * buf,int count)190 bfin_jc_write(struct tty_struct *tty, const unsigned char *buf, int count)
191 {
192 int i;
193 console_lock();
194 i = bfin_jc_circ_write(buf, count);
195 console_unlock();
196 wake_up_process(bfin_jc_kthread);
197 return i;
198 }
199
200 static void
bfin_jc_flush_chars(struct tty_struct * tty)201 bfin_jc_flush_chars(struct tty_struct *tty)
202 {
203 wake_up_process(bfin_jc_kthread);
204 }
205
206 static int
bfin_jc_write_room(struct tty_struct * tty)207 bfin_jc_write_room(struct tty_struct *tty)
208 {
209 return circ_free(&bfin_jc_write_buf);
210 }
211
212 static int
bfin_jc_chars_in_buffer(struct tty_struct * tty)213 bfin_jc_chars_in_buffer(struct tty_struct *tty)
214 {
215 return circ_cnt(&bfin_jc_write_buf);
216 }
217
218 static void
bfin_jc_wait_until_sent(struct tty_struct * tty,int timeout)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
bfin_jc_init(void)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_buf;
255
256 bfin_jc_driver = alloc_tty_driver(1);
257 if (!bfin_jc_driver)
258 goto err_driver;
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 err_driver:
279 kfree(bfin_jc_write_buf.buf);
280 err_buf:
281 kthread_stop(bfin_jc_kthread);
282 return ret;
283 }
284 module_init(bfin_jc_init);
285
bfin_jc_exit(void)286 static void __exit bfin_jc_exit(void)
287 {
288 kthread_stop(bfin_jc_kthread);
289 kfree(bfin_jc_write_buf.buf);
290 tty_unregister_driver(bfin_jc_driver);
291 put_tty_driver(bfin_jc_driver);
292 }
293 module_exit(bfin_jc_exit);
294
295 #if defined(CONFIG_BFIN_JTAG_COMM_CONSOLE) || defined(CONFIG_EARLY_PRINTK)
296 static void
bfin_jc_straight_buffer_write(const char * buf,unsigned count)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
bfin_jc_console_write(struct console * co,const char * buf,unsigned count)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 *
bfin_jc_console_device(struct console * co,int * index)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
bfin_jc_console_init(void)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
bfin_jc_early_write(struct console * co,const char * buf,unsigned int count)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
bfin_jc_early_init(unsigned int port,unsigned int cflag)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");
369