1 // SPDX-License-Identifier: GPL-2.0+
5  * State machine for handling IPMI KCS interfaces.
15  * This state machine is taken from the state machine in the IPMI spec,
30 /* kcs_debug is a bit-field
31  *	KCS_DEBUG_ENABLE -	turned on for now
32  *	KCS_DEBUG_MSG    -	commands and their responses
33  *	KCS_DEBUG_STATES -	state machine
51 	 * was added to the state machine in the spec to wait for the
72 	 * State to transition to the error handler, this was added to
73 	 * the state machine in the spec to be sure IBF was there.
78 	 * First stage error handler, wait for the interface to
84 	 * The abort cmd has been written, wait for the interface to
90 	 * We wrote some data to the interface, wait for it to switch
95 	/* The hardware failed to follow the state machine. */
109 	enum kcs_states  state;  member
128 	kcs->state = KCS_IDLE;  in init_kcs_data()
129 	kcs->io = io;  in init_kcs_data()
130 	kcs->write_pos = 0;  in init_kcs_data()
131 	kcs->write_count = 0;  in init_kcs_data()
132 	kcs->orig_write_count = 0;  in init_kcs_data()
133 	kcs->read_pos = 0;  in init_kcs_data()
134 	kcs->error_retries = 0;  in init_kcs_data()
135 	kcs->truncated = 0;  in init_kcs_data()
136 	kcs->ibf_timeout = IBF_RETRY_TIMEOUT;  in init_kcs_data()
137 	kcs->obf_timeout = OBF_RETRY_TIMEOUT;  in init_kcs_data()
145 	return kcs->io->inputb(kcs->io, 1);  in read_status()
150 	return kcs->io->inputb(kcs->io, 0);  in read_data()
155 	kcs->io->outputb(kcs->io, 1, data);  in write_cmd()
160 	kcs->io->outputb(kcs->io, 0, data);  in write_data()
182 	write_data(kcs, kcs->write_data[kcs->write_pos]);  in write_next_byte()
183 	(kcs->write_pos)++;  in write_next_byte()
184 	(kcs->write_count)--;  in write_next_byte()
189 	(kcs->error_retries)++;  in start_error_recovery()
190 	if (kcs->error_retries > MAX_ERROR_RETRIES) {  in start_error_recovery()
192 			dev_dbg(kcs->io->dev, "ipmi_kcs_sm: kcs hosed: %s\n",  in start_error_recovery()
194 		kcs->state = KCS_HOSED;  in start_error_recovery()
196 		kcs->error0_timeout = jiffies + ERROR0_OBF_WAIT_JIFFIES;  in start_error_recovery()
197 		kcs->state = KCS_ERROR0;  in start_error_recovery()
203 	if (kcs->read_pos >= MAX_KCS_READ_SIZE) {  in read_next_byte()
206 		kcs->truncated = 1;  in read_next_byte()
208 		kcs->read_data[kcs->read_pos] = read_data(kcs);  in read_next_byte()
209 		(kcs->read_pos)++;  in read_next_byte()
218 		kcs->ibf_timeout -= time;  in check_ibf()
219 		if (kcs->ibf_timeout < 0) {  in check_ibf()
221 			kcs->ibf_timeout = IBF_RETRY_TIMEOUT;  in check_ibf()
226 	kcs->ibf_timeout = IBF_RETRY_TIMEOUT;  in check_ibf()
234 		kcs->obf_timeout -= time;  in check_obf()
235 		if (kcs->obf_timeout < 0) {  in check_obf()
236 			kcs->obf_timeout = OBF_RETRY_TIMEOUT;  in check_obf()
242 	kcs->obf_timeout = OBF_RETRY_TIMEOUT;  in check_obf()
254 	kcs->write_count = kcs->orig_write_count;  in restart_kcs_transaction()
255 	kcs->write_pos = 0;  in restart_kcs_transaction()
256 	kcs->read_pos = 0;  in restart_kcs_transaction()
257 	kcs->state = KCS_WAIT_WRITE_START;  in restart_kcs_transaction()
258 	kcs->ibf_timeout = IBF_RETRY_TIMEOUT;  in restart_kcs_transaction()
259 	kcs->obf_timeout = OBF_RETRY_TIMEOUT;  in restart_kcs_transaction()
273 	if ((kcs->state != KCS_IDLE) && (kcs->state != KCS_HOSED)) {  in start_kcs_transaction()
274 		dev_warn(kcs->io->dev, "KCS in invalid state %d\n", kcs->state);  in start_kcs_transaction()
279 		dev_dbg(kcs->io->dev, "%s -", __func__);  in start_kcs_transaction()
284 	kcs->error_retries = 0;  in start_kcs_transaction()
285 	memcpy(kcs->write_data, data, size);  in start_kcs_transaction()
286 	kcs->write_count = size;  in start_kcs_transaction()
287 	kcs->orig_write_count = size;  in start_kcs_transaction()
288 	kcs->write_pos = 0;  in start_kcs_transaction()
289 	kcs->read_pos = 0;  in start_kcs_transaction()
290 	kcs->state = KCS_START_OP;  in start_kcs_transaction()
291 	kcs->ibf_timeout = IBF_RETRY_TIMEOUT;  in start_kcs_transaction()
292 	kcs->obf_timeout = OBF_RETRY_TIMEOUT;  in start_kcs_transaction()
299 	if (length < kcs->read_pos) {  in get_kcs_result()
300 		kcs->read_pos = length;  in get_kcs_result()
301 		kcs->truncated = 1;  in get_kcs_result()
304 	memcpy(data, kcs->read_data, kcs->read_pos);  in get_kcs_result()
306 	if ((length >= 3) && (kcs->read_pos < 3)) {  in get_kcs_result()
310 		kcs->read_pos = 3;  in get_kcs_result()
312 	if (kcs->truncated) {  in get_kcs_result()
319 		kcs->truncated = 0;  in get_kcs_result()
322 	return kcs->read_pos;  in get_kcs_result()
326  * This implements the state machine defined in the IPMI manual, see
328  * sections delimited by "Wait for IBF" and this will become clear.
333 	unsigned char state;  in kcs_event()  local
338 		dev_dbg(kcs->io->dev,  in kcs_event()
339 			"KCS: State = %d, %x\n", kcs->state, status);  in kcs_event()
341 	/* All states wait for ibf, so just do it here. */  in kcs_event()
345 	/* Just about everything looks at the KCS state, so grab that, too. */  in kcs_event()
346 	state = GET_STATUS_STATE(status);  in kcs_event()
348 	switch (kcs->state) {  in kcs_event()
359 		if (state != KCS_IDLE_STATE) {  in kcs_event()
361 					     "State machine not idle at start");  in kcs_event()
367 		kcs->state = KCS_WAIT_WRITE_START;  in kcs_event()
371 		if (state != KCS_WRITE_STATE) {  in kcs_event()
374 				"Not in write state at write start");  in kcs_event()
378 		if (kcs->write_count == 1) {  in kcs_event()
380 			kcs->state = KCS_WAIT_WRITE_END;  in kcs_event()
383 			kcs->state = KCS_WAIT_WRITE;  in kcs_event()
388 		if (state != KCS_WRITE_STATE) {  in kcs_event()
390 					     "Not in write state for write");  in kcs_event()
394 		if (kcs->write_count == 1) {  in kcs_event()
396 			kcs->state = KCS_WAIT_WRITE_END;  in kcs_event()
403 		if (state != KCS_WRITE_STATE) {  in kcs_event()
405 					     "Not in write state"  in kcs_event()
411 		kcs->state = KCS_WAIT_READ;  in kcs_event()
415 		if ((state != KCS_READ_STATE) && (state != KCS_IDLE_STATE)) {  in kcs_event()
418 				"Not in read or idle in read state");  in kcs_event()
422 		if (state == KCS_READ_STATE) {  in kcs_event()
428 			 * We don't implement this exactly like the state  in kcs_event()
433 			 * handle clearing out obf in idle state if it  in kcs_event()
437 			kcs->orig_write_count = 0;  in kcs_event()
438 			kcs->state = KCS_IDLE;  in kcs_event()
448 			if (time_before(jiffies, kcs->error0_timeout))  in kcs_event()
451 		kcs->state = KCS_ERROR1;  in kcs_event()
457 		kcs->state = KCS_ERROR2;  in kcs_event()
461 		if (state != KCS_READ_STATE) {  in kcs_event()
463 					     "Not in read state for error2");  in kcs_event()
471 		kcs->state = KCS_ERROR3;  in kcs_event()
475 		if (state != KCS_IDLE_STATE) {  in kcs_event()
477 					     "Not in idle state for error3");  in kcs_event()
485 		if (kcs->orig_write_count) {  in kcs_event()
488 			kcs->state = KCS_IDLE;  in kcs_event()
497 	if (kcs->state == KCS_HOSED) {  in kcs_event()
498 		init_kcs_data(kcs, kcs->io);  in kcs_event()
514 	 * (assuming a properly functioning, self-initialized BMC)  in kcs_detect()