1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * OTG Finite State Machine from OTG spec
4  *
5  * Copyright (C) 2007,2008 Freescale Semiconductor, Inc.
6  *
7  * Author:	Li Yang <LeoLi@freescale.com>
8  *		Jerry Huang <Chang-Ming.Huang@freescale.com>
9  */
10 
11 #include <linux/module.h>
12 #include <linux/kernel.h>
13 #include <linux/types.h>
14 #include <linux/mutex.h>
15 #include <linux/delay.h>
16 #include <linux/usb.h>
17 #include <linux/usb/gadget.h>
18 #include <linux/usb/otg.h>
19 #include <linux/usb/otg-fsm.h>
20 
21 #ifdef VERBOSE
22 #define VDBG(fmt, args...) pr_debug("[%s]  " fmt, \
23 				 __func__, ## args)
24 #else
25 #define VDBG(stuff...)	do {} while (0)
26 #endif
27 
28 /* Change USB protocol when there is a protocol change */
otg_set_protocol(struct otg_fsm * fsm,int protocol)29 static int otg_set_protocol(struct otg_fsm *fsm, int protocol)
30 {
31 	int ret = 0;
32 
33 	if (fsm->protocol != protocol) {
34 		VDBG("Changing role fsm->protocol= %d; new protocol= %d\n",
35 			fsm->protocol, protocol);
36 		/* stop old protocol */
37 		if (fsm->protocol == PROTO_HOST)
38 			ret = otg_start_host(fsm, 0);
39 		else if (fsm->protocol == PROTO_GADGET)
40 			ret = otg_start_gadget(fsm, 0);
41 		if (ret)
42 			return ret;
43 
44 		/* start new protocol */
45 		if (protocol == PROTO_HOST)
46 			ret = otg_start_host(fsm, 1);
47 		else if (protocol == PROTO_GADGET)
48 			ret = otg_start_gadget(fsm, 1);
49 		if (ret)
50 			return ret;
51 
52 		fsm->protocol = protocol;
53 		return 0;
54 	}
55 
56 	return 0;
57 }
58 
59 /* Called when leaving a state.  Do state clean up jobs here */
otg_leave_state(struct otg_fsm * fsm,enum usb_otg_state old_state)60 static void otg_leave_state(struct otg_fsm *fsm, enum usb_otg_state old_state)
61 {
62 	switch (old_state) {
63 	case OTG_STATE_B_IDLE:
64 		otg_del_timer(fsm, B_SE0_SRP);
65 		fsm->b_se0_srp = 0;
66 		fsm->adp_sns = 0;
67 		fsm->adp_prb = 0;
68 		break;
69 	case OTG_STATE_B_SRP_INIT:
70 		fsm->data_pulse = 0;
71 		fsm->b_srp_done = 0;
72 		break;
73 	case OTG_STATE_B_PERIPHERAL:
74 		if (fsm->otg->gadget)
75 			fsm->otg->gadget->host_request_flag = 0;
76 		break;
77 	case OTG_STATE_B_WAIT_ACON:
78 		otg_del_timer(fsm, B_ASE0_BRST);
79 		fsm->b_ase0_brst_tmout = 0;
80 		break;
81 	case OTG_STATE_B_HOST:
82 		break;
83 	case OTG_STATE_A_IDLE:
84 		fsm->adp_prb = 0;
85 		break;
86 	case OTG_STATE_A_WAIT_VRISE:
87 		otg_del_timer(fsm, A_WAIT_VRISE);
88 		fsm->a_wait_vrise_tmout = 0;
89 		break;
90 	case OTG_STATE_A_WAIT_BCON:
91 		otg_del_timer(fsm, A_WAIT_BCON);
92 		fsm->a_wait_bcon_tmout = 0;
93 		break;
94 	case OTG_STATE_A_HOST:
95 		otg_del_timer(fsm, A_WAIT_ENUM);
96 		break;
97 	case OTG_STATE_A_SUSPEND:
98 		otg_del_timer(fsm, A_AIDL_BDIS);
99 		fsm->a_aidl_bdis_tmout = 0;
100 		fsm->a_suspend_req_inf = 0;
101 		break;
102 	case OTG_STATE_A_PERIPHERAL:
103 		otg_del_timer(fsm, A_BIDL_ADIS);
104 		fsm->a_bidl_adis_tmout = 0;
105 		if (fsm->otg->gadget)
106 			fsm->otg->gadget->host_request_flag = 0;
107 		break;
108 	case OTG_STATE_A_WAIT_VFALL:
109 		otg_del_timer(fsm, A_WAIT_VFALL);
110 		fsm->a_wait_vfall_tmout = 0;
111 		otg_del_timer(fsm, A_WAIT_VRISE);
112 		break;
113 	case OTG_STATE_A_VBUS_ERR:
114 		break;
115 	default:
116 		break;
117 	}
118 }
119 
otg_hnp_polling_work(struct work_struct * work)120 static void otg_hnp_polling_work(struct work_struct *work)
121 {
122 	struct otg_fsm *fsm = container_of(to_delayed_work(work),
123 				struct otg_fsm, hnp_polling_work);
124 	struct usb_device *udev;
125 	enum usb_otg_state state = fsm->otg->state;
126 	u8 flag;
127 	int retval;
128 
129 	if (state != OTG_STATE_A_HOST && state != OTG_STATE_B_HOST)
130 		return;
131 
132 	udev = usb_hub_find_child(fsm->otg->host->root_hub, 1);
133 	if (!udev) {
134 		dev_err(fsm->otg->host->controller,
135 			"no usb dev connected, can't start HNP polling\n");
136 		return;
137 	}
138 
139 	*fsm->host_req_flag = 0;
140 	/* Get host request flag from connected USB device */
141 	retval = usb_control_msg(udev,
142 				usb_rcvctrlpipe(udev, 0),
143 				USB_REQ_GET_STATUS,
144 				USB_DIR_IN | USB_RECIP_DEVICE,
145 				0,
146 				OTG_STS_SELECTOR,
147 				fsm->host_req_flag,
148 				1,
149 				USB_CTRL_GET_TIMEOUT);
150 	if (retval != 1) {
151 		dev_err(&udev->dev, "Get one byte OTG status failed\n");
152 		return;
153 	}
154 
155 	flag = *fsm->host_req_flag;
156 	if (flag == 0) {
157 		/* Continue HNP polling */
158 		schedule_delayed_work(&fsm->hnp_polling_work,
159 					msecs_to_jiffies(T_HOST_REQ_POLL));
160 		return;
161 	} else if (flag != HOST_REQUEST_FLAG) {
162 		dev_err(&udev->dev, "host request flag %d is invalid\n", flag);
163 		return;
164 	}
165 
166 	/* Host request flag is set */
167 	if (state == OTG_STATE_A_HOST) {
168 		/* Set b_hnp_enable */
169 		if (!fsm->otg->host->b_hnp_enable) {
170 			retval = usb_control_msg(udev,
171 					usb_sndctrlpipe(udev, 0),
172 					USB_REQ_SET_FEATURE, 0,
173 					USB_DEVICE_B_HNP_ENABLE,
174 					0, NULL, 0,
175 					USB_CTRL_SET_TIMEOUT);
176 			if (retval >= 0)
177 				fsm->otg->host->b_hnp_enable = 1;
178 		}
179 		fsm->a_bus_req = 0;
180 	} else if (state == OTG_STATE_B_HOST) {
181 		fsm->b_bus_req = 0;
182 	}
183 
184 	otg_statemachine(fsm);
185 }
186 
otg_start_hnp_polling(struct otg_fsm * fsm)187 static void otg_start_hnp_polling(struct otg_fsm *fsm)
188 {
189 	/*
190 	 * The memory of host_req_flag should be allocated by
191 	 * controller driver, otherwise, hnp polling is not started.
192 	 */
193 	if (!fsm->host_req_flag)
194 		return;
195 
196 	INIT_DELAYED_WORK(&fsm->hnp_polling_work, otg_hnp_polling_work);
197 	schedule_delayed_work(&fsm->hnp_polling_work,
198 					msecs_to_jiffies(T_HOST_REQ_POLL));
199 }
200 
201 /* Called when entering a state */
otg_set_state(struct otg_fsm * fsm,enum usb_otg_state new_state)202 static int otg_set_state(struct otg_fsm *fsm, enum usb_otg_state new_state)
203 {
204 	if (fsm->otg->state == new_state)
205 		return 0;
206 	VDBG("Set state: %s\n", usb_otg_state_string(new_state));
207 	otg_leave_state(fsm, fsm->otg->state);
208 	switch (new_state) {
209 	case OTG_STATE_B_IDLE:
210 		otg_drv_vbus(fsm, 0);
211 		otg_chrg_vbus(fsm, 0);
212 		otg_loc_conn(fsm, 0);
213 		otg_loc_sof(fsm, 0);
214 		/*
215 		 * Driver is responsible for starting ADP probing
216 		 * if ADP sensing times out.
217 		 */
218 		otg_start_adp_sns(fsm);
219 		otg_set_protocol(fsm, PROTO_UNDEF);
220 		otg_add_timer(fsm, B_SE0_SRP);
221 		break;
222 	case OTG_STATE_B_SRP_INIT:
223 		otg_start_pulse(fsm);
224 		otg_loc_sof(fsm, 0);
225 		otg_set_protocol(fsm, PROTO_UNDEF);
226 		otg_add_timer(fsm, B_SRP_FAIL);
227 		break;
228 	case OTG_STATE_B_PERIPHERAL:
229 		otg_chrg_vbus(fsm, 0);
230 		otg_loc_sof(fsm, 0);
231 		otg_set_protocol(fsm, PROTO_GADGET);
232 		otg_loc_conn(fsm, 1);
233 		break;
234 	case OTG_STATE_B_WAIT_ACON:
235 		otg_chrg_vbus(fsm, 0);
236 		otg_loc_conn(fsm, 0);
237 		otg_loc_sof(fsm, 0);
238 		otg_set_protocol(fsm, PROTO_HOST);
239 		otg_add_timer(fsm, B_ASE0_BRST);
240 		fsm->a_bus_suspend = 0;
241 		break;
242 	case OTG_STATE_B_HOST:
243 		otg_chrg_vbus(fsm, 0);
244 		otg_loc_conn(fsm, 0);
245 		otg_loc_sof(fsm, 1);
246 		otg_set_protocol(fsm, PROTO_HOST);
247 		usb_bus_start_enum(fsm->otg->host,
248 				fsm->otg->host->otg_port);
249 		otg_start_hnp_polling(fsm);
250 		break;
251 	case OTG_STATE_A_IDLE:
252 		otg_drv_vbus(fsm, 0);
253 		otg_chrg_vbus(fsm, 0);
254 		otg_loc_conn(fsm, 0);
255 		otg_loc_sof(fsm, 0);
256 		otg_start_adp_prb(fsm);
257 		otg_set_protocol(fsm, PROTO_HOST);
258 		break;
259 	case OTG_STATE_A_WAIT_VRISE:
260 		otg_drv_vbus(fsm, 1);
261 		otg_loc_conn(fsm, 0);
262 		otg_loc_sof(fsm, 0);
263 		otg_set_protocol(fsm, PROTO_HOST);
264 		otg_add_timer(fsm, A_WAIT_VRISE);
265 		break;
266 	case OTG_STATE_A_WAIT_BCON:
267 		otg_drv_vbus(fsm, 1);
268 		otg_loc_conn(fsm, 0);
269 		otg_loc_sof(fsm, 0);
270 		otg_set_protocol(fsm, PROTO_HOST);
271 		otg_add_timer(fsm, A_WAIT_BCON);
272 		break;
273 	case OTG_STATE_A_HOST:
274 		otg_drv_vbus(fsm, 1);
275 		otg_loc_conn(fsm, 0);
276 		otg_loc_sof(fsm, 1);
277 		otg_set_protocol(fsm, PROTO_HOST);
278 		/*
279 		 * When HNP is triggered while a_bus_req = 0, a_host will
280 		 * suspend too fast to complete a_set_b_hnp_en
281 		 */
282 		if (!fsm->a_bus_req || fsm->a_suspend_req_inf)
283 			otg_add_timer(fsm, A_WAIT_ENUM);
284 		otg_start_hnp_polling(fsm);
285 		break;
286 	case OTG_STATE_A_SUSPEND:
287 		otg_drv_vbus(fsm, 1);
288 		otg_loc_conn(fsm, 0);
289 		otg_loc_sof(fsm, 0);
290 		otg_set_protocol(fsm, PROTO_HOST);
291 		otg_add_timer(fsm, A_AIDL_BDIS);
292 
293 		break;
294 	case OTG_STATE_A_PERIPHERAL:
295 		otg_loc_sof(fsm, 0);
296 		otg_set_protocol(fsm, PROTO_GADGET);
297 		otg_drv_vbus(fsm, 1);
298 		otg_loc_conn(fsm, 1);
299 		otg_add_timer(fsm, A_BIDL_ADIS);
300 		break;
301 	case OTG_STATE_A_WAIT_VFALL:
302 		otg_drv_vbus(fsm, 0);
303 		otg_loc_conn(fsm, 0);
304 		otg_loc_sof(fsm, 0);
305 		otg_set_protocol(fsm, PROTO_HOST);
306 		otg_add_timer(fsm, A_WAIT_VFALL);
307 		break;
308 	case OTG_STATE_A_VBUS_ERR:
309 		otg_drv_vbus(fsm, 0);
310 		otg_loc_conn(fsm, 0);
311 		otg_loc_sof(fsm, 0);
312 		otg_set_protocol(fsm, PROTO_UNDEF);
313 		break;
314 	default:
315 		break;
316 	}
317 
318 	fsm->otg->state = new_state;
319 	fsm->state_changed = 1;
320 	return 0;
321 }
322 
323 /* State change judgement */
otg_statemachine(struct otg_fsm * fsm)324 int otg_statemachine(struct otg_fsm *fsm)
325 {
326 	enum usb_otg_state state;
327 
328 	mutex_lock(&fsm->lock);
329 
330 	state = fsm->otg->state;
331 	fsm->state_changed = 0;
332 	/* State machine state change judgement */
333 
334 	switch (state) {
335 	case OTG_STATE_UNDEFINED:
336 		VDBG("fsm->id = %d\n", fsm->id);
337 		if (fsm->id)
338 			otg_set_state(fsm, OTG_STATE_B_IDLE);
339 		else
340 			otg_set_state(fsm, OTG_STATE_A_IDLE);
341 		break;
342 	case OTG_STATE_B_IDLE:
343 		if (!fsm->id)
344 			otg_set_state(fsm, OTG_STATE_A_IDLE);
345 		else if (fsm->b_sess_vld && fsm->otg->gadget)
346 			otg_set_state(fsm, OTG_STATE_B_PERIPHERAL);
347 		else if ((fsm->b_bus_req || fsm->adp_change || fsm->power_up) &&
348 				fsm->b_ssend_srp && fsm->b_se0_srp)
349 			otg_set_state(fsm, OTG_STATE_B_SRP_INIT);
350 		break;
351 	case OTG_STATE_B_SRP_INIT:
352 		if (!fsm->id || fsm->b_srp_done)
353 			otg_set_state(fsm, OTG_STATE_B_IDLE);
354 		break;
355 	case OTG_STATE_B_PERIPHERAL:
356 		if (!fsm->id || !fsm->b_sess_vld)
357 			otg_set_state(fsm, OTG_STATE_B_IDLE);
358 		else if (fsm->b_bus_req && fsm->otg->
359 				gadget->b_hnp_enable && fsm->a_bus_suspend)
360 			otg_set_state(fsm, OTG_STATE_B_WAIT_ACON);
361 		break;
362 	case OTG_STATE_B_WAIT_ACON:
363 		if (fsm->a_conn)
364 			otg_set_state(fsm, OTG_STATE_B_HOST);
365 		else if (!fsm->id || !fsm->b_sess_vld)
366 			otg_set_state(fsm, OTG_STATE_B_IDLE);
367 		else if (fsm->a_bus_resume || fsm->b_ase0_brst_tmout) {
368 			fsm->b_ase0_brst_tmout = 0;
369 			otg_set_state(fsm, OTG_STATE_B_PERIPHERAL);
370 		}
371 		break;
372 	case OTG_STATE_B_HOST:
373 		if (!fsm->id || !fsm->b_sess_vld)
374 			otg_set_state(fsm, OTG_STATE_B_IDLE);
375 		else if (!fsm->b_bus_req || !fsm->a_conn || fsm->test_device)
376 			otg_set_state(fsm, OTG_STATE_B_PERIPHERAL);
377 		break;
378 	case OTG_STATE_A_IDLE:
379 		if (fsm->id)
380 			otg_set_state(fsm, OTG_STATE_B_IDLE);
381 		else if (!fsm->a_bus_drop && (fsm->a_bus_req ||
382 			  fsm->a_srp_det || fsm->adp_change || fsm->power_up))
383 			otg_set_state(fsm, OTG_STATE_A_WAIT_VRISE);
384 		break;
385 	case OTG_STATE_A_WAIT_VRISE:
386 		if (fsm->a_vbus_vld)
387 			otg_set_state(fsm, OTG_STATE_A_WAIT_BCON);
388 		else if (fsm->id || fsm->a_bus_drop ||
389 				fsm->a_wait_vrise_tmout)
390 			otg_set_state(fsm, OTG_STATE_A_WAIT_VFALL);
391 		break;
392 	case OTG_STATE_A_WAIT_BCON:
393 		if (!fsm->a_vbus_vld)
394 			otg_set_state(fsm, OTG_STATE_A_VBUS_ERR);
395 		else if (fsm->b_conn)
396 			otg_set_state(fsm, OTG_STATE_A_HOST);
397 		else if (fsm->id || fsm->a_bus_drop || fsm->a_wait_bcon_tmout)
398 			otg_set_state(fsm, OTG_STATE_A_WAIT_VFALL);
399 		break;
400 	case OTG_STATE_A_HOST:
401 		if (fsm->id || fsm->a_bus_drop)
402 			otg_set_state(fsm, OTG_STATE_A_WAIT_VFALL);
403 		else if ((!fsm->a_bus_req || fsm->a_suspend_req_inf) &&
404 				fsm->otg->host->b_hnp_enable)
405 			otg_set_state(fsm, OTG_STATE_A_SUSPEND);
406 		else if (!fsm->b_conn)
407 			otg_set_state(fsm, OTG_STATE_A_WAIT_BCON);
408 		else if (!fsm->a_vbus_vld)
409 			otg_set_state(fsm, OTG_STATE_A_VBUS_ERR);
410 		break;
411 	case OTG_STATE_A_SUSPEND:
412 		if (!fsm->b_conn && fsm->otg->host->b_hnp_enable)
413 			otg_set_state(fsm, OTG_STATE_A_PERIPHERAL);
414 		else if (!fsm->b_conn && !fsm->otg->host->b_hnp_enable)
415 			otg_set_state(fsm, OTG_STATE_A_WAIT_BCON);
416 		else if (fsm->a_bus_req || fsm->b_bus_resume)
417 			otg_set_state(fsm, OTG_STATE_A_HOST);
418 		else if (fsm->id || fsm->a_bus_drop || fsm->a_aidl_bdis_tmout)
419 			otg_set_state(fsm, OTG_STATE_A_WAIT_VFALL);
420 		else if (!fsm->a_vbus_vld)
421 			otg_set_state(fsm, OTG_STATE_A_VBUS_ERR);
422 		break;
423 	case OTG_STATE_A_PERIPHERAL:
424 		if (fsm->id || fsm->a_bus_drop)
425 			otg_set_state(fsm, OTG_STATE_A_WAIT_VFALL);
426 		else if (fsm->a_bidl_adis_tmout || fsm->b_bus_suspend)
427 			otg_set_state(fsm, OTG_STATE_A_WAIT_BCON);
428 		else if (!fsm->a_vbus_vld)
429 			otg_set_state(fsm, OTG_STATE_A_VBUS_ERR);
430 		break;
431 	case OTG_STATE_A_WAIT_VFALL:
432 		if (fsm->a_wait_vfall_tmout)
433 			otg_set_state(fsm, OTG_STATE_A_IDLE);
434 		break;
435 	case OTG_STATE_A_VBUS_ERR:
436 		if (fsm->id || fsm->a_bus_drop || fsm->a_clr_err)
437 			otg_set_state(fsm, OTG_STATE_A_WAIT_VFALL);
438 		break;
439 	default:
440 		break;
441 	}
442 	mutex_unlock(&fsm->lock);
443 
444 	VDBG("quit statemachine, changed = %d\n", fsm->state_changed);
445 	return fsm->state_changed;
446 }
447 EXPORT_SYMBOL_GPL(otg_statemachine);
448 MODULE_LICENSE("GPL");
449