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 38static inline uint32_t bfin_write_emudat(uint32_t emudat) 39{ 40 __asm__ __volatile__("emudat = %0;" : : "d"(emudat)); 41 return emudat; 42} 43 44static inline uint32_t bfin_read_emudat(void) 45{ 46 uint32_t emudat; 47 __asm__ __volatile__("%0 = emudat;" : "=d"(emudat)); 48 return emudat; 49} 50 51static 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 63static struct tty_driver *bfin_jc_driver; 64static struct task_struct *bfin_jc_kthread; 65static struct tty_struct * volatile bfin_jc_tty; 66static unsigned long bfin_jc_count; 67static DEFINE_MUTEX(bfin_jc_tty_mutex); 68static volatile struct circ_buf bfin_jc_write_buf; 69 70static int 71bfin_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 149static int 150bfin_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 161static void 162bfin_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 172static int 173bfin_jc_circ_write(const unsigned char *buf, int count) 174{ 175 int i; 176 count = min(count, circ_free(&bfin_jc_write_buf)); 177 pr_debug("going to write chunk of %i bytes\n", count); 178 for (i = 0; i < count; ++i) 179 circ_byte(&bfin_jc_write_buf, bfin_jc_write_buf.head + i) = buf[i]; 180 bfin_jc_write_buf.head += i; 181 return i; 182} 183 184#ifndef CONFIG_BFIN_JTAG_COMM_CONSOLE 185# define acquire_console_sem() 186# define release_console_sem() 187#endif 188static int 189bfin_jc_write(struct tty_struct *tty, const unsigned char *buf, int count) 190{ 191 int i; 192 acquire_console_sem(); 193 i = bfin_jc_circ_write(buf, count); 194 release_console_sem(); 195 wake_up_process(bfin_jc_kthread); 196 return i; 197} 198 199static void 200bfin_jc_flush_chars(struct tty_struct *tty) 201{ 202 wake_up_process(bfin_jc_kthread); 203} 204 205static int 206bfin_jc_write_room(struct tty_struct *tty) 207{ 208 return circ_free(&bfin_jc_write_buf); 209} 210 211static int 212bfin_jc_chars_in_buffer(struct tty_struct *tty) 213{ 214 return circ_cnt(&bfin_jc_write_buf); 215} 216 217static void 218bfin_jc_wait_until_sent(struct tty_struct *tty, int timeout) 219{ 220 unsigned long expire = jiffies + timeout; 221 while (!circ_empty(&bfin_jc_write_buf)) { 222 if (signal_pending(current)) 223 break; 224 if (time_after(jiffies, expire)) 225 break; 226 } 227} 228 229static const struct tty_operations bfin_jc_ops = { 230 .open = bfin_jc_open, 231 .close = bfin_jc_close, 232 .write = bfin_jc_write, 233 /*.put_char = bfin_jc_put_char,*/ 234 .flush_chars = bfin_jc_flush_chars, 235 .write_room = bfin_jc_write_room, 236 .chars_in_buffer = bfin_jc_chars_in_buffer, 237 .wait_until_sent = bfin_jc_wait_until_sent, 238}; 239 240static int __init bfin_jc_init(void) 241{ 242 int ret; 243 244 bfin_jc_kthread = kthread_create(bfin_jc_emudat_manager, NULL, DRV_NAME); 245 if (IS_ERR(bfin_jc_kthread)) 246 return PTR_ERR(bfin_jc_kthread); 247 248 ret = -ENOMEM; 249 250 bfin_jc_write_buf.head = bfin_jc_write_buf.tail = 0; 251 bfin_jc_write_buf.buf = kmalloc(CIRC_SIZE, GFP_KERNEL); 252 if (!bfin_jc_write_buf.buf) 253 goto err; 254 255 bfin_jc_driver = alloc_tty_driver(1); 256 if (!bfin_jc_driver) 257 goto err; 258 259 bfin_jc_driver->owner = THIS_MODULE; 260 bfin_jc_driver->driver_name = DRV_NAME; 261 bfin_jc_driver->name = DEV_NAME; 262 bfin_jc_driver->type = TTY_DRIVER_TYPE_SERIAL; 263 bfin_jc_driver->subtype = SERIAL_TYPE_NORMAL; 264 bfin_jc_driver->init_termios = tty_std_termios; 265 tty_set_operations(bfin_jc_driver, &bfin_jc_ops); 266 267 ret = tty_register_driver(bfin_jc_driver); 268 if (ret) 269 goto err; 270 271 pr_init(KERN_INFO DRV_NAME ": initialized\n"); 272 273 return 0; 274 275 err: 276 put_tty_driver(bfin_jc_driver); 277 kfree(bfin_jc_write_buf.buf); 278 kthread_stop(bfin_jc_kthread); 279 return ret; 280} 281module_init(bfin_jc_init); 282 283static void __exit bfin_jc_exit(void) 284{ 285 kthread_stop(bfin_jc_kthread); 286 kfree(bfin_jc_write_buf.buf); 287 tty_unregister_driver(bfin_jc_driver); 288 put_tty_driver(bfin_jc_driver); 289} 290module_exit(bfin_jc_exit); 291 292#if defined(CONFIG_BFIN_JTAG_COMM_CONSOLE) || defined(CONFIG_EARLY_PRINTK) 293static void 294bfin_jc_straight_buffer_write(const char *buf, unsigned count) 295{ 296 unsigned ate = 0; 297 while (bfin_read_DBGSTAT() & EMUDOF) 298 continue; 299 bfin_write_emudat(count); 300 while (ate < count) { 301 while (bfin_read_DBGSTAT() & EMUDOF) 302 continue; 303 bfin_write_emudat_chars(buf[ate], buf[ate+1], buf[ate+2], buf[ate+3]); 304 ate += 4; 305 } 306} 307#endif 308 309#ifdef CONFIG_BFIN_JTAG_COMM_CONSOLE 310static void 311bfin_jc_console_write(struct console *co, const char *buf, unsigned count) 312{ 313 if (bfin_jc_kthread == NULL) 314 bfin_jc_straight_buffer_write(buf, count); 315 else 316 bfin_jc_circ_write(buf, count); 317} 318 319static struct tty_driver * 320bfin_jc_console_device(struct console *co, int *index) 321{ 322 *index = co->index; 323 return bfin_jc_driver; 324} 325 326static struct console bfin_jc_console = { 327 .name = DEV_NAME, 328 .write = bfin_jc_console_write, 329 .device = bfin_jc_console_device, 330 .flags = CON_ANYTIME | CON_PRINTBUFFER, 331 .index = -1, 332}; 333 334static int __init bfin_jc_console_init(void) 335{ 336 register_console(&bfin_jc_console); 337 return 0; 338} 339console_initcall(bfin_jc_console_init); 340#endif 341 342#ifdef CONFIG_EARLY_PRINTK 343static void __init 344bfin_jc_early_write(struct console *co, const char *buf, unsigned int count) 345{ 346 bfin_jc_straight_buffer_write(buf, count); 347} 348 349static struct __initdata console bfin_jc_early_console = { 350 .name = "early_BFJC", 351 .write = bfin_jc_early_write, 352 .flags = CON_ANYTIME | CON_PRINTBUFFER, 353 .index = -1, 354}; 355 356struct console * __init 357bfin_jc_early_init(unsigned int port, unsigned int cflag) 358{ 359 return &bfin_jc_early_console; 360} 361#endif 362 363MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>"); 364MODULE_DESCRIPTION("TTY over Blackfin JTAG Communication"); 365MODULE_LICENSE("GPL"); 366