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
126 				  struct si_sm_io *io, enum kcs_states state)  in init_kcs_data_with_state()  argument
128 	kcs->state = state;  in init_kcs_data_with_state()
129 	kcs->io = io;  in init_kcs_data_with_state()
130 	kcs->write_pos = 0;  in init_kcs_data_with_state()
131 	kcs->write_count = 0;  in init_kcs_data_with_state()
132 	kcs->orig_write_count = 0;  in init_kcs_data_with_state()
133 	kcs->read_pos = 0;  in init_kcs_data_with_state()
134 	kcs->error_retries = 0;  in init_kcs_data_with_state()
135 	kcs->truncated = 0;  in init_kcs_data_with_state()
136 	kcs->ibf_timeout = IBF_RETRY_TIMEOUT;  in init_kcs_data_with_state()
137 	kcs->obf_timeout = OBF_RETRY_TIMEOUT;  in init_kcs_data_with_state()
151 	return kcs->io->inputb(kcs->io, 1);  in read_status()
156 	return kcs->io->inputb(kcs->io, 0);  in read_data()
161 	kcs->io->outputb(kcs->io, 1, data);  in write_cmd()
166 	kcs->io->outputb(kcs->io, 0, data);  in write_data()
188 	write_data(kcs, kcs->write_data[kcs->write_pos]);  in write_next_byte()
189 	(kcs->write_pos)++;  in write_next_byte()
190 	(kcs->write_count)--;  in write_next_byte()
195 	(kcs->error_retries)++;  in start_error_recovery()
196 	if (kcs->error_retries > MAX_ERROR_RETRIES) {  in start_error_recovery()
198 			dev_dbg(kcs->io->dev, "ipmi_kcs_sm: kcs hosed: %s\n",  in start_error_recovery()
200 		kcs->state = KCS_HOSED;  in start_error_recovery()
202 		kcs->error0_timeout = jiffies + ERROR0_OBF_WAIT_JIFFIES;  in start_error_recovery()
203 		kcs->state = KCS_ERROR0;  in start_error_recovery()
209 	if (kcs->read_pos >= MAX_KCS_READ_SIZE) {  in read_next_byte()
212 		kcs->truncated = 1;  in read_next_byte()
214 		kcs->read_data[kcs->read_pos] = read_data(kcs);  in read_next_byte()
215 		(kcs->read_pos)++;  in read_next_byte()
224 		kcs->ibf_timeout -= time;  in check_ibf()
225 		if (kcs->ibf_timeout < 0) {  in check_ibf()
227 			kcs->ibf_timeout = IBF_RETRY_TIMEOUT;  in check_ibf()
232 	kcs->ibf_timeout = IBF_RETRY_TIMEOUT;  in check_ibf()
240 		kcs->obf_timeout -= time;  in check_obf()
241 		if (kcs->obf_timeout < 0) {  in check_obf()
242 			kcs->obf_timeout = OBF_RETRY_TIMEOUT;  in check_obf()
248 	kcs->obf_timeout = OBF_RETRY_TIMEOUT;  in check_obf()
260 	kcs->write_count = kcs->orig_write_count;  in restart_kcs_transaction()
261 	kcs->write_pos = 0;  in restart_kcs_transaction()
262 	kcs->read_pos = 0;  in restart_kcs_transaction()
263 	kcs->state = KCS_WAIT_WRITE_START;  in restart_kcs_transaction()
264 	kcs->ibf_timeout = IBF_RETRY_TIMEOUT;  in restart_kcs_transaction()
265 	kcs->obf_timeout = OBF_RETRY_TIMEOUT;  in restart_kcs_transaction()
279 	if (kcs->state != KCS_IDLE) {  in start_kcs_transaction()
280 		dev_warn(kcs->io->dev, "KCS in invalid state %d\n", kcs->state);  in start_kcs_transaction()
285 		dev_dbg(kcs->io->dev, "%s -", __func__);  in start_kcs_transaction()
290 	kcs->error_retries = 0;  in start_kcs_transaction()
291 	memcpy(kcs->write_data, data, size);  in start_kcs_transaction()
292 	kcs->write_count = size;  in start_kcs_transaction()
293 	kcs->orig_write_count = size;  in start_kcs_transaction()
294 	kcs->write_pos = 0;  in start_kcs_transaction()
295 	kcs->read_pos = 0;  in start_kcs_transaction()
296 	kcs->state = KCS_START_OP;  in start_kcs_transaction()
297 	kcs->ibf_timeout = IBF_RETRY_TIMEOUT;  in start_kcs_transaction()
298 	kcs->obf_timeout = OBF_RETRY_TIMEOUT;  in start_kcs_transaction()
305 	if (length < kcs->read_pos) {  in get_kcs_result()
306 		kcs->read_pos = length;  in get_kcs_result()
307 		kcs->truncated = 1;  in get_kcs_result()
310 	memcpy(data, kcs->read_data, kcs->read_pos);  in get_kcs_result()
312 	if ((length >= 3) && (kcs->read_pos < 3)) {  in get_kcs_result()
316 		kcs->read_pos = 3;  in get_kcs_result()
318 	if (kcs->truncated) {  in get_kcs_result()
325 		kcs->truncated = 0;  in get_kcs_result()
328 	return kcs->read_pos;  in get_kcs_result()
332  * This implements the state machine defined in the IPMI manual, see
334  * sections delimited by "Wait for IBF" and this will become clear.
339 	unsigned char state;  in kcs_event()  local
344 		dev_dbg(kcs->io->dev,  in kcs_event()
345 			"KCS: State = %d, %x\n", kcs->state, status);  in kcs_event()
347 	/* All states wait for ibf, so just do it here. */  in kcs_event()
351 	/* Just about everything looks at the KCS state, so grab that, too. */  in kcs_event()
352 	state = GET_STATUS_STATE(status);  in kcs_event()
354 	switch (kcs->state) {  in kcs_event()
365 		if (state != KCS_IDLE_STATE) {  in kcs_event()
367 					     "State machine not idle at start");  in kcs_event()
373 		kcs->state = KCS_WAIT_WRITE_START;  in kcs_event()
377 		if (state != KCS_WRITE_STATE) {  in kcs_event()
380 				"Not in write state at write start");  in kcs_event()
384 		if (kcs->write_count == 1) {  in kcs_event()
386 			kcs->state = KCS_WAIT_WRITE_END;  in kcs_event()
389 			kcs->state = KCS_WAIT_WRITE;  in kcs_event()
394 		if (state != KCS_WRITE_STATE) {  in kcs_event()
396 					     "Not in write state for write");  in kcs_event()
400 		if (kcs->write_count == 1) {  in kcs_event()
402 			kcs->state = KCS_WAIT_WRITE_END;  in kcs_event()
409 		if (state != KCS_WRITE_STATE) {  in kcs_event()
411 					     "Not in write state"  in kcs_event()
417 		kcs->state = KCS_WAIT_READ;  in kcs_event()
421 		if ((state != KCS_READ_STATE) && (state != KCS_IDLE_STATE)) {  in kcs_event()
424 				"Not in read or idle in read state");  in kcs_event()
428 		if (state == KCS_READ_STATE) {  in kcs_event()
434 			 * We don't implement this exactly like the state  in kcs_event()
439 			 * handle clearing out obf in idle state if it  in kcs_event()
443 			kcs->orig_write_count = 0;  in kcs_event()
444 			kcs->state = KCS_IDLE;  in kcs_event()
454 			if (time_before(jiffies, kcs->error0_timeout))  in kcs_event()
457 		kcs->state = KCS_ERROR1;  in kcs_event()
463 		kcs->state = KCS_ERROR2;  in kcs_event()
467 		if (state != KCS_READ_STATE) {  in kcs_event()
469 					     "Not in read state for error2");  in kcs_event()
477 		kcs->state = KCS_ERROR3;  in kcs_event()
481 		if (state != KCS_IDLE_STATE) {  in kcs_event()
483 					     "Not in idle state for error3");  in kcs_event()
491 		if (kcs->orig_write_count) {  in kcs_event()
494 			kcs->state = KCS_IDLE;  in kcs_event()
503 	if (kcs->state == KCS_HOSED) {  in kcs_event()
504 		init_kcs_data_with_state(kcs, kcs->io, KCS_ERROR0);  in kcs_event()
520 	 * (assuming a properly functioning, self-initialized BMC)  in kcs_detect()