via-macii.c 14.1 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550
/*
 * Device driver for the via ADB on (many) Mac II-class machines
 *
 * Based on the original ADB keyboard handler Copyright (c) 1997 Alan Cox
 * Also derived from code Copyright (C) 1996 Paul Mackerras.
 *
 * With various updates provided over the years by Michael Schmitz,
 * Guideo Koerber and others.
 *
 * Rewrite for Unified ADB by Joshua M. Thompson (funaho@jurai.org)
 *
 * 1999-08-02 (jmt) - Initial rewrite for Unified ADB.
 * 2000-03-29 Tony Mantler <tonym@mac.linux-m68k.org>
 * 				- Big overhaul, should actually work now.
 * 2006-12-31 Finn Thain <fthain@telegraphics.com.au> - Another overhaul.
 *
 * Suggested reading:
 *   Inside Macintosh, ch. 5 ADB Manager
 *   Guide to the Macinstosh Family Hardware, ch. 8 Apple Desktop Bus
 *   Rockwell R6522 VIA datasheet
 *
 * Apple's "ADB Analyzer" bus sniffer is invaluable:
 *   ftp://ftp.apple.com/developer/Tool_Chest/Devices_-_Hardware/Apple_Desktop_Bus/
 */
 
#include <stdarg.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/adb.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <asm/macintosh.h>
#include <asm/macints.h>
#include <asm/mac_via.h>
#include <asm/system.h>

static volatile unsigned char *via;

/* VIA registers - spaced 0x200 bytes apart */
#define RS		0x200		/* skip between registers */
#define B		0		/* B-side data */
#define A		RS		/* A-side data */
#define DIRB		(2*RS)		/* B-side direction (1=output) */
#define DIRA		(3*RS)		/* A-side direction (1=output) */
#define T1CL		(4*RS)		/* Timer 1 ctr/latch (low 8 bits) */
#define T1CH		(5*RS)		/* Timer 1 counter (high 8 bits) */
#define T1LL		(6*RS)		/* Timer 1 latch (low 8 bits) */
#define T1LH		(7*RS)		/* Timer 1 latch (high 8 bits) */
#define T2CL		(8*RS)		/* Timer 2 ctr/latch (low 8 bits) */
#define T2CH		(9*RS)		/* Timer 2 counter (high 8 bits) */
#define SR		(10*RS)		/* Shift register */
#define ACR		(11*RS)		/* Auxiliary control register */
#define PCR		(12*RS)		/* Peripheral control register */
#define IFR		(13*RS)		/* Interrupt flag register */
#define IER		(14*RS)		/* Interrupt enable register */
#define ANH		(15*RS)		/* A-side data, no handshake */

/* Bits in B data register: all active low */
#define CTLR_IRQ	0x08		/* Controller rcv status (input) */
#define ST_MASK		0x30		/* mask for selecting ADB state bits */

/* Bits in ACR */
#define SR_CTRL		0x1c		/* Shift register control bits */
#define SR_EXT		0x0c		/* Shift on external clock */
#define SR_OUT		0x10		/* Shift out if 1 */

/* Bits in IFR and IER */
#define IER_SET		0x80		/* set bits in IER */
#define IER_CLR		0		/* clear bits in IER */
#define SR_INT		0x04		/* Shift register full/empty */

/* ADB transaction states according to GMHW */
#define ST_CMD		0x00		/* ADB state: command byte */
#define ST_EVEN		0x10		/* ADB state: even data byte */
#define ST_ODD		0x20		/* ADB state: odd data byte */
#define ST_IDLE		0x30		/* ADB state: idle, nothing to send */

static int  macii_init_via(void);
static void macii_start(void);
static irqreturn_t macii_interrupt(int irq, void *arg);
static void macii_queue_poll(void);

static int macii_probe(void);
static int macii_init(void);
static int macii_send_request(struct adb_request *req, int sync);
static int macii_write(struct adb_request *req);
static int macii_autopoll(int devs);
static void macii_poll(void);
static int macii_reset_bus(void);

struct adb_driver via_macii_driver = {
	"Mac II",
	macii_probe,
	macii_init,
	macii_send_request,
	macii_autopoll,
	macii_poll,
	macii_reset_bus
};

static enum macii_state {
	idle,
	sending,
	reading,
	read_done,
} macii_state;

static struct adb_request *current_req; /* first request struct in the queue */
static struct adb_request *last_req;     /* last request struct in the queue */
static unsigned char reply_buf[16];        /* storage for autopolled replies */
static unsigned char *reply_ptr;     /* next byte in reply_buf or req->reply */
static int reading_reply;        /* store reply in reply_buf else req->reply */
static int data_index;      /* index of the next byte to send from req->data */
static int reply_len; /* number of bytes received in reply_buf or req->reply */
static int status;          /* VIA's ADB status bits captured upon interrupt */
static int last_status;              /* status bits as at previous interrupt */
static int srq_asserted;     /* have to poll for the device that asserted it */
static int command_byte;         /* the most recent command byte transmitted */
static int autopoll_devs;      /* bits set are device addresses to be polled */

/* Sanity check for request queue. Doesn't check for cycles. */
static int request_is_queued(struct adb_request *req) {
	struct adb_request *cur;
	unsigned long flags;
	local_irq_save(flags);
	cur = current_req;
	while (cur) {
		if (cur == req) {
			local_irq_restore(flags);
			return 1;
		}
		cur = cur->next;
	}
	local_irq_restore(flags);
	return 0;
}

/* Check for MacII style ADB */
static int macii_probe(void)
{
	if (macintosh_config->adb_type != MAC_ADB_II) return -ENODEV;

	via = via1;

	printk("adb: Mac II ADB Driver v1.0 for Unified ADB\n");
	return 0;
}

/* Initialize the driver */
int macii_init(void)
{
	unsigned long flags;
	int err;
	
	local_irq_save(flags);
	
	err = macii_init_via();
	if (err) goto out;

	err = request_irq(IRQ_MAC_ADB, macii_interrupt, IRQ_FLG_LOCK, "ADB",
			  macii_interrupt);
	if (err) goto out;

	macii_state = idle;
out:
	local_irq_restore(flags);
	return err;
}

/* initialize the hardware */	
static int macii_init_via(void)
{
	unsigned char x;

	/* We want CTLR_IRQ as input and ST_EVEN | ST_ODD as output lines. */
	via[DIRB] = (via[DIRB] | ST_EVEN | ST_ODD) & ~CTLR_IRQ;

	/* Set up state: idle */
	via[B] |= ST_IDLE;
	last_status = via[B] & (ST_MASK|CTLR_IRQ);

	/* Shift register on input */
	via[ACR] = (via[ACR] & ~SR_CTRL) | SR_EXT;

	/* Wipe any pending data and int */
	x = via[SR];

	return 0;
}

/* Send an ADB poll (Talk Register 0 command prepended to the request queue) */
static void macii_queue_poll(void)
{
	/* No point polling the active device as it will never assert SRQ, so
	 * poll the next device in the autopoll list. This could leave us
	 * stuck in a polling loop if an unprobed device is asserting SRQ.
	 * In theory, that could only happen if a device was plugged in after
	 * probing started. Unplugging it again will break the cycle.
	 * (Simply polling the next higher device often ends up polling almost
	 * every device (after wrapping around), which takes too long.)
	 */
	int device_mask;
	int next_device;
	static struct adb_request req;

	if (!autopoll_devs) return;

	device_mask = (1 << (((command_byte & 0xF0) >> 4) + 1)) - 1;
	if (autopoll_devs & ~device_mask)
		next_device = ffs(autopoll_devs & ~device_mask) - 1;
	else
		next_device = ffs(autopoll_devs) - 1;

	BUG_ON(request_is_queued(&req));

	adb_request(&req, NULL, ADBREQ_NOSEND, 1,
	            ADB_READREG(next_device, 0));

	req.sent = 0;
	req.complete = 0;
	req.reply_len = 0;
	req.next = current_req;

	if (current_req != NULL) {
		current_req = &req;
	} else {
		current_req = &req;
		last_req = &req;
	}
}

/* Send an ADB request; if sync, poll out the reply 'till it's done */
static int macii_send_request(struct adb_request *req, int sync)
{
	int err;
	unsigned long flags;

	BUG_ON(request_is_queued(req));

	local_irq_save(flags);
	err = macii_write(req);
	local_irq_restore(flags);

	if (!err && sync) {
		while (!req->complete) {
			macii_poll();
		}
		BUG_ON(request_is_queued(req));
	}

	return err;
}

/* Send an ADB request (append to request queue) */
static int macii_write(struct adb_request *req)
{
	if (req->nbytes < 2 || req->data[0] != ADB_PACKET || req->nbytes > 15) {
		req->complete = 1;
		return -EINVAL;
	}
	
	req->next = NULL;
	req->sent = 0;
	req->complete = 0;
	req->reply_len = 0;

	if (current_req != NULL) {
		last_req->next = req;
		last_req = req;
	} else {
		current_req = req;
		last_req = req;
		if (macii_state == idle) macii_start();
	}
	return 0;
}

/* Start auto-polling */
static int macii_autopoll(int devs)
{
	static struct adb_request req;
	unsigned long flags;
	int err = 0;

	/* bit 1 == device 1, and so on. */
	autopoll_devs = devs & 0xFFFE;

	if (!autopoll_devs) return 0;

	local_irq_save(flags);

	if (current_req == NULL) {
		/* Send a Talk Reg 0. The controller will repeatedly transmit
		 * this as long as it is idle.
		 */
		adb_request(&req, NULL, ADBREQ_NOSEND, 1,
		            ADB_READREG(ffs(autopoll_devs) - 1, 0));
		err = macii_write(&req);
	}

	local_irq_restore(flags);
	return err;
}

static inline int need_autopoll(void) {
	/* Was the last command Talk Reg 0
	 * and is the target on the autopoll list?
	 */
	if ((command_byte & 0x0F) == 0x0C &&
	    ((1 << ((command_byte & 0xF0) >> 4)) & autopoll_devs))
		return 0;
	return 1;
}

/* Prod the chip without interrupts */
static void macii_poll(void)
{
	disable_irq(IRQ_MAC_ADB);
	macii_interrupt(0, NULL);
	enable_irq(IRQ_MAC_ADB);
}

/* Reset the bus */
static int macii_reset_bus(void)
{
	static struct adb_request req;
	
	if (request_is_queued(&req))
		return 0;

	/* Command = 0, Address = ignored */
	adb_request(&req, NULL, 0, 1, ADB_BUSRESET);

	/* Don't want any more requests during the Global Reset low time. */
	udelay(3000);

	return 0;
}

/* Start sending ADB packet */
static void macii_start(void)
{
	struct adb_request *req;

	req = current_req;

	BUG_ON(req == NULL);

	BUG_ON(macii_state != idle);

	/* Now send it. Be careful though, that first byte of the request
	 * is actually ADB_PACKET; the real data begins at index 1!
	 * And req->nbytes is the number of bytes of real data plus one.
	 */

	/* store command byte */
	command_byte = req->data[1];
	/* Output mode */
	via[ACR] |= SR_OUT;
	/* Load data */
	via[SR] = req->data[1];
	/* set ADB state to 'command' */
	via[B] = (via[B] & ~ST_MASK) | ST_CMD;

	macii_state = sending;
	data_index = 2;
}

/*
 * The notorious ADB interrupt handler - does all of the protocol handling.
 * Relies on the ADB controller sending and receiving data, thereby
 * generating shift register interrupts (SR_INT) for us. This means there has
 * to be activity on the ADB bus. The chip will poll to achieve this.
 *
 * The basic ADB state machine was left unchanged from the original MacII code
 * by Alan Cox, which was based on the CUDA driver for PowerMac. 
 * The syntax of the ADB status lines is totally different on MacII,
 * though. MacII uses the states Command -> Even -> Odd -> Even ->...-> Idle
 * for sending and Idle -> Even -> Odd -> Even ->...-> Idle for receiving.
 * Start and end of a receive packet are signalled by asserting /IRQ on the
 * interrupt line (/IRQ means the CTLR_IRQ bit in port B; not to be confused
 * with the VIA shift register interrupt. /IRQ never actually interrupts the
 * processor, it's just an ordinary input.)
 */
static irqreturn_t macii_interrupt(int irq, void *arg)
{
	int x;
	static int entered;
	struct adb_request *req;

	if (!arg) {
		/* Clear the SR IRQ flag when polling. */
		if (via[IFR] & SR_INT)
			via[IFR] = SR_INT;
		else
			return IRQ_NONE;
	}

	BUG_ON(entered++);

	last_status = status;
	status = via[B] & (ST_MASK|CTLR_IRQ);

	switch (macii_state) {
		case idle:
			if (reading_reply) {
				reply_ptr = current_req->reply;
			} else {
				BUG_ON(current_req != NULL);
				reply_ptr = reply_buf;
			}

			x = via[SR];

			if ((status & CTLR_IRQ) && (x == 0xFF)) {
				/* Bus timeout without SRQ sequence:
				 *     data is "FF" while CTLR_IRQ is "H"
				 */
				reply_len = 0;
				srq_asserted = 0;
				macii_state = read_done;
			} else {
				macii_state = reading;
				*reply_ptr = x;
				reply_len = 1;
			}

			/* set ADB state = even for first data byte */
			via[B] = (via[B] & ~ST_MASK) | ST_EVEN;
			break;

		case sending:
			req = current_req;
			if (data_index >= req->nbytes) {
				req->sent = 1;
				macii_state = idle;

				if (req->reply_expected) {
					reading_reply = 1;
				} else {
					req->complete = 1;
					current_req = req->next;
					if (req->done) (*req->done)(req);

					if (current_req)
						macii_start();
					else
						if (need_autopoll())
							macii_autopoll(autopoll_devs);
				}

				if (macii_state == idle) {
					/* reset to shift in */
					via[ACR] &= ~SR_OUT;
					x = via[SR];
					/* set ADB state idle - might get SRQ */
					via[B] = (via[B] & ~ST_MASK) | ST_IDLE;
				}
			} else {
				via[SR] = req->data[data_index++];

				if ( (via[B] & ST_MASK) == ST_CMD ) {
					/* just sent the command byte, set to EVEN */
					via[B] = (via[B] & ~ST_MASK) | ST_EVEN;
				} else {
					/* invert state bits, toggle ODD/EVEN */
					via[B] ^= ST_MASK;
				}
			}
			break;

		case reading:
			x = via[SR];
			BUG_ON((status & ST_MASK) == ST_CMD ||
			       (status & ST_MASK) == ST_IDLE);

			/* Bus timeout with SRQ sequence:
			 *     data is "XX FF"      while CTLR_IRQ is "L L"
			 * End of packet without SRQ sequence:
			 *     data is "XX...YY 00" while CTLR_IRQ is "L...H L"
			 * End of packet SRQ sequence:
			 *     data is "XX...YY 00" while CTLR_IRQ is "L...L L"
			 * (where XX is the first response byte and
			 * YY is the last byte of valid response data.)
			 */

			srq_asserted = 0;
			if (!(status & CTLR_IRQ)) {
				if (x == 0xFF) {
					if (!(last_status & CTLR_IRQ)) {
						macii_state = read_done;
						reply_len = 0;
						srq_asserted = 1;
					}
				} else if (x == 0x00) {
					macii_state = read_done;
					if (!(last_status & CTLR_IRQ))
						srq_asserted = 1;
				}
			}

			if (macii_state == reading) {
				BUG_ON(reply_len > 15);
				reply_ptr++;
				*reply_ptr = x;
				reply_len++;
			}

			/* invert state bits, toggle ODD/EVEN */
			via[B] ^= ST_MASK;
			break;

		case read_done:
			x = via[SR];

			if (reading_reply) {
				reading_reply = 0;
				req = current_req;
				req->reply_len = reply_len;
				req->complete = 1;
				current_req = req->next;
				if (req->done) (*req->done)(req);
			} else if (reply_len && autopoll_devs)
				adb_input(reply_buf, reply_len, 0);

			macii_state = idle;

			/* SRQ seen before, initiate poll now */
			if (srq_asserted)
				macii_queue_poll();

			if (current_req)
				macii_start();
			else
				if (need_autopoll())
					macii_autopoll(autopoll_devs);

			if (macii_state == idle)
				via[B] = (via[B] & ~ST_MASK) | ST_IDLE;
			break;

		default:
		break;
	}

	entered--;
	return IRQ_HANDLED;
}