2 * TTY over Blackfin JTAG Communication
4 * Copyright 2008-2009 Analog Devices Inc.
6 * Enter bugs at http://blackfin.uclinux.org/
8 * Licensed under the GPL-2 or later.
11 #define DRV_NAME "bfin-jtag-comm"
12 #define DEV_NAME "ttyBFJC"
13 #define pr_fmt(fmt) DRV_NAME ": " fmt
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>
30 #define pr_init(fmt, args...) ({ static const __initconst char __fmt[] = fmt; printk(__fmt, ## args); })
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 */
38 static inline uint32_t bfin_write_emudat(uint32_t emudat
)
40 __asm__
__volatile__("emudat = %0;" : : "d"(emudat
));
44 static inline uint32_t bfin_read_emudat(void)
47 __asm__
__volatile__("%0 = emudat;" : "=d"(emudat
));
51 static inline uint32_t bfin_write_emudat_chars(char a
, char b
, char c
, char d
)
53 return bfin_write_emudat((a
<< 0) | (b
<< 8) | (c
<< 16) | (d
<< 24));
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])
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
;
69 bfin_jc_emudat_manager(void *arg
)
71 uint32_t inbound_len
= 0, outbound_len
= 0;
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
);
83 /* no data available, so just chill */
84 if (!(bfin_read_DBGSTAT() & EMUDIF
) && circ_empty(&bfin_jc_write_buf
)) {
85 pr_debug("waiting for data (in_len = %i) (circ: %i %i)\n",
86 inbound_len
, bfin_jc_write_buf
.tail
, bfin_jc_write_buf
.head
);
91 schedule_timeout_interruptible(HZ
);
95 /* if incoming data is ready, eat it */
96 if (bfin_read_DBGSTAT() & EMUDIF
) {
97 uint32_t emudat
= bfin_read_emudat();
98 if (inbound_len
== 0) {
99 pr_debug("incoming length: 0x%08x\n", emudat
);
100 inbound_len
= emudat
;
102 size_t num_chars
= (4 <= inbound_len
? 4 : inbound_len
);
103 pr_debug(" incoming data: 0x%08x (pushing %zu)\n", emudat
, num_chars
);
104 inbound_len
-= num_chars
;
105 tty_insert_flip_string(&port
, (unsigned char *)&emudat
, num_chars
);
106 tty_flip_buffer_push(&port
);
110 /* if outgoing data is ready, post it */
111 if (!(bfin_read_DBGSTAT() & EMUDOF
) && !circ_empty(&bfin_jc_write_buf
)) {
112 if (outbound_len
== 0) {
113 outbound_len
= circ_cnt(&bfin_jc_write_buf
);
114 bfin_write_emudat(outbound_len
);
115 pr_debug("outgoing length: 0x%08x\n", outbound_len
);
117 int tail
= bfin_jc_write_buf
.tail
;
118 size_t ate
= (4 <= outbound_len
? 4 : outbound_len
);
120 bfin_write_emudat_chars(
121 circ_byte(&bfin_jc_write_buf
, tail
+ 0),
122 circ_byte(&bfin_jc_write_buf
, tail
+ 1),
123 circ_byte(&bfin_jc_write_buf
, tail
+ 2),
124 circ_byte(&bfin_jc_write_buf
, tail
+ 3)
126 bfin_jc_write_buf
.tail
+= ate
;
130 pr_debug(" outgoing data: 0x%08x (pushing %zu)\n", emudat
, ate
);
136 __set_current_state(TASK_RUNNING
);
141 bfin_jc_open(struct tty_struct
*tty
, struct file
*filp
)
145 spin_lock_irqsave(&port
.lock
, flags
);
147 spin_unlock_irqrestore(&port
.lock
, flags
);
148 tty_port_tty_set(&port
, tty
);
149 wake_up_process(bfin_jc_kthread
);
154 bfin_jc_close(struct tty_struct
*tty
, struct file
*filp
)
159 spin_lock_irqsave(&port
.lock
, flags
);
160 last
= --port
.count
== 0;
161 spin_unlock_irqrestore(&port
.lock
, flags
);
163 tty_port_tty_set(&port
, NULL
);
164 wake_up_process(bfin_jc_kthread
);
167 /* XXX: we dont handle the put_char() case where we must handle count = 1 */
169 bfin_jc_circ_write(const unsigned char *buf
, int count
)
172 count
= min(count
, circ_free(&bfin_jc_write_buf
));
173 pr_debug("going to write chunk of %i bytes\n", count
);
174 for (i
= 0; i
< count
; ++i
)
175 circ_byte(&bfin_jc_write_buf
, bfin_jc_write_buf
.head
+ i
) = buf
[i
];
176 bfin_jc_write_buf
.head
+= i
;
180 #ifndef CONFIG_BFIN_JTAG_COMM_CONSOLE
181 # define console_lock()
182 # define console_unlock()
185 bfin_jc_write(struct tty_struct
*tty
, const unsigned char *buf
, int count
)
189 i
= bfin_jc_circ_write(buf
, count
);
191 wake_up_process(bfin_jc_kthread
);
196 bfin_jc_flush_chars(struct tty_struct
*tty
)
198 wake_up_process(bfin_jc_kthread
);
202 bfin_jc_write_room(struct tty_struct
*tty
)
204 return circ_free(&bfin_jc_write_buf
);
208 bfin_jc_chars_in_buffer(struct tty_struct
*tty
)
210 return circ_cnt(&bfin_jc_write_buf
);
214 bfin_jc_wait_until_sent(struct tty_struct
*tty
, int timeout
)
216 unsigned long expire
= jiffies
+ timeout
;
217 while (!circ_empty(&bfin_jc_write_buf
)) {
218 if (signal_pending(current
))
220 if (time_after(jiffies
, expire
))
225 static const struct tty_operations bfin_jc_ops
= {
226 .open
= bfin_jc_open
,
227 .close
= bfin_jc_close
,
228 .write
= bfin_jc_write
,
229 /*.put_char = bfin_jc_put_char,*/
230 .flush_chars
= bfin_jc_flush_chars
,
231 .write_room
= bfin_jc_write_room
,
232 .chars_in_buffer
= bfin_jc_chars_in_buffer
,
233 .wait_until_sent
= bfin_jc_wait_until_sent
,
236 static int __init
bfin_jc_init(void)
240 bfin_jc_kthread
= kthread_create(bfin_jc_emudat_manager
, NULL
, DRV_NAME
);
241 if (IS_ERR(bfin_jc_kthread
))
242 return PTR_ERR(bfin_jc_kthread
);
246 bfin_jc_write_buf
.head
= bfin_jc_write_buf
.tail
= 0;
247 bfin_jc_write_buf
.buf
= kmalloc(CIRC_SIZE
, GFP_KERNEL
);
248 if (!bfin_jc_write_buf
.buf
)
251 bfin_jc_driver
= alloc_tty_driver(1);
255 tty_port_init(&port
);
257 bfin_jc_driver
->driver_name
= DRV_NAME
;
258 bfin_jc_driver
->name
= DEV_NAME
;
259 bfin_jc_driver
->type
= TTY_DRIVER_TYPE_SERIAL
;
260 bfin_jc_driver
->subtype
= SERIAL_TYPE_NORMAL
;
261 bfin_jc_driver
->init_termios
= tty_std_termios
;
262 tty_set_operations(bfin_jc_driver
, &bfin_jc_ops
);
263 tty_port_link_device(&port
, bfin_jc_driver
, 0);
265 ret
= tty_register_driver(bfin_jc_driver
);
269 pr_init(KERN_INFO DRV_NAME
": initialized\n");
274 tty_port_destroy(&port
);
275 put_tty_driver(bfin_jc_driver
);
277 kfree(bfin_jc_write_buf
.buf
);
279 kthread_stop(bfin_jc_kthread
);
282 module_init(bfin_jc_init
);
284 static void __exit
bfin_jc_exit(void)
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 tty_port_destroy(&port
);
292 module_exit(bfin_jc_exit
);
294 #if defined(CONFIG_BFIN_JTAG_COMM_CONSOLE) || defined(CONFIG_EARLY_PRINTK)
296 bfin_jc_straight_buffer_write(const char *buf
, unsigned count
)
299 while (bfin_read_DBGSTAT() & EMUDOF
)
301 bfin_write_emudat(count
);
302 while (ate
< count
) {
303 while (bfin_read_DBGSTAT() & EMUDOF
)
305 bfin_write_emudat_chars(buf
[ate
], buf
[ate
+1], buf
[ate
+2], buf
[ate
+3]);
311 #ifdef CONFIG_BFIN_JTAG_COMM_CONSOLE
313 bfin_jc_console_write(struct console
*co
, const char *buf
, unsigned count
)
315 if (bfin_jc_kthread
== NULL
)
316 bfin_jc_straight_buffer_write(buf
, count
);
318 bfin_jc_circ_write(buf
, count
);
321 static struct tty_driver
*
322 bfin_jc_console_device(struct console
*co
, int *index
)
325 return bfin_jc_driver
;
328 static struct console bfin_jc_console
= {
330 .write
= bfin_jc_console_write
,
331 .device
= bfin_jc_console_device
,
332 .flags
= CON_ANYTIME
| CON_PRINTBUFFER
,
336 static int __init
bfin_jc_console_init(void)
338 register_console(&bfin_jc_console
);
341 console_initcall(bfin_jc_console_init
);
344 #ifdef CONFIG_EARLY_PRINTK
346 bfin_jc_early_write(struct console
*co
, const char *buf
, unsigned int count
)
348 bfin_jc_straight_buffer_write(buf
, count
);
351 static struct console bfin_jc_early_console __initdata
= {
352 .name
= "early_BFJC",
353 .write
= bfin_jc_early_write
,
354 .flags
= CON_ANYTIME
| CON_PRINTBUFFER
,
358 struct console
* __init
359 bfin_jc_early_init(unsigned int port
, unsigned int cflag
)
361 return &bfin_jc_early_console
;
365 MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
366 MODULE_DESCRIPTION("TTY over Blackfin JTAG Communication");
367 MODULE_LICENSE("GPL");