1/*
2 * Function Control Protocol (IEC 61883-1) helper functions
3 *
4 * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
5 * Licensed under the terms of the GNU General Public License, version 2.
6 */
7
8#include <linux/device.h>
9#include <linux/firewire.h>
10#include <linux/firewire-constants.h>
11#include <linux/list.h>
12#include <linux/module.h>
13#include <linux/slab.h>
14#include <linux/sched.h>
15#include <linux/spinlock.h>
16#include <linux/wait.h>
17#include <linux/delay.h>
18#include "fcp.h"
19#include "lib.h"
20#include "amdtp.h"
21
22#define CTS_AVC 0x00
23
24#define ERROR_RETRIES	3
25#define ERROR_DELAY_MS	5
26#define FCP_TIMEOUT_MS	125
27
28int avc_general_set_sig_fmt(struct fw_unit *unit, unsigned int rate,
29			    enum avc_general_plug_dir dir,
30			    unsigned short pid)
31{
32	unsigned int sfc;
33	u8 *buf;
34	bool flag;
35	int err;
36
37	flag = false;
38	for (sfc = 0; sfc < CIP_SFC_COUNT; sfc++) {
39		if (amdtp_rate_table[sfc] == rate) {
40			flag = true;
41			break;
42		}
43	}
44	if (!flag)
45		return -EINVAL;
46
47	buf = kzalloc(8, GFP_KERNEL);
48	if (buf == NULL)
49		return -ENOMEM;
50
51	buf[0] = 0x00;		/* AV/C CONTROL */
52	buf[1] = 0xff;		/* UNIT */
53	if (dir == AVC_GENERAL_PLUG_DIR_IN)
54		buf[2] = 0x19;	/* INPUT PLUG SIGNAL FORMAT */
55	else
56		buf[2] = 0x18;	/* OUTPUT PLUG SIGNAL FORMAT */
57	buf[3] = 0xff & pid;	/* plug id */
58	buf[4] = 0x90;		/* EOH_1, Form_1, FMT. AM824 */
59	buf[5] = 0x07 & sfc;	/* FDF-hi. AM824, frequency */
60	buf[6] = 0xff;		/* FDF-mid. AM824, SYT hi (not used)*/
61	buf[7] = 0xff;		/* FDF-low. AM824, SYT lo (not used) */
62
63	/* do transaction and check buf[1-5] are the same against command */
64	err = fcp_avc_transaction(unit, buf, 8, buf, 8,
65				  BIT(1) | BIT(2) | BIT(3) | BIT(4) | BIT(5));
66	if (err >= 0 && err < 8)
67		err = -EIO;
68	else if (buf[0] == 0x08) /* NOT IMPLEMENTED */
69		err = -ENOSYS;
70	else if (buf[0] == 0x0a) /* REJECTED */
71		err = -EINVAL;
72	if (err < 0)
73		goto end;
74
75	err = 0;
76end:
77	kfree(buf);
78	return err;
79}
80EXPORT_SYMBOL(avc_general_set_sig_fmt);
81
82int avc_general_get_sig_fmt(struct fw_unit *unit, unsigned int *rate,
83			    enum avc_general_plug_dir dir,
84			    unsigned short pid)
85{
86	unsigned int sfc;
87	u8 *buf;
88	int err;
89
90	buf = kzalloc(8, GFP_KERNEL);
91	if (buf == NULL)
92		return -ENOMEM;
93
94	buf[0] = 0x01;		/* AV/C STATUS */
95	buf[1] = 0xff;		/* Unit */
96	if (dir == AVC_GENERAL_PLUG_DIR_IN)
97		buf[2] = 0x19;	/* INPUT PLUG SIGNAL FORMAT */
98	else
99		buf[2] = 0x18;	/* OUTPUT PLUG SIGNAL FORMAT */
100	buf[3] = 0xff & pid;	/* plug id */
101	buf[4] = 0x90;		/* EOH_1, Form_1, FMT. AM824 */
102	buf[5] = 0xff;		/* FDF-hi. AM824, frequency */
103	buf[6] = 0xff;		/* FDF-mid. AM824, SYT hi (not used) */
104	buf[7] = 0xff;		/* FDF-low. AM824, SYT lo (not used) */
105
106	/* do transaction and check buf[1-4] are the same against command */
107	err = fcp_avc_transaction(unit, buf, 8, buf, 8,
108				  BIT(1) | BIT(2) | BIT(3) | BIT(4));
109	if (err >= 0 && err < 8)
110		err = -EIO;
111	else if (buf[0] == 0x08) /* NOT IMPLEMENTED */
112		err = -ENOSYS;
113	else if (buf[0] == 0x0a) /* REJECTED */
114		err = -EINVAL;
115	else if (buf[0] == 0x0b) /* IN TRANSITION */
116		err = -EAGAIN;
117	if (err < 0)
118		goto end;
119
120	/* check sfc field and pick up rate */
121	sfc = 0x07 & buf[5];
122	if (sfc >= CIP_SFC_COUNT) {
123		err = -EAGAIN;	/* also in transition */
124		goto end;
125	}
126
127	*rate = amdtp_rate_table[sfc];
128	err = 0;
129end:
130	kfree(buf);
131	return err;
132}
133EXPORT_SYMBOL(avc_general_get_sig_fmt);
134
135int avc_general_get_plug_info(struct fw_unit *unit, unsigned int subunit_type,
136			      unsigned int subunit_id, unsigned int subfunction,
137			      u8 info[AVC_PLUG_INFO_BUF_BYTES])
138{
139	u8 *buf;
140	int err;
141
142	/* extended subunit in spec.4.2 is not supported */
143	if ((subunit_type == 0x1E) || (subunit_id == 5))
144		return -EINVAL;
145
146	buf = kzalloc(8, GFP_KERNEL);
147	if (buf == NULL)
148		return -ENOMEM;
149
150	buf[0] = 0x01;	/* AV/C STATUS */
151	/* UNIT or Subunit, Functionblock */
152	buf[1] = ((subunit_type & 0x1f) << 3) | (subunit_id & 0x7);
153	buf[2] = 0x02;	/* PLUG INFO */
154	buf[3] = 0xff & subfunction;
155
156	err = fcp_avc_transaction(unit, buf, 8, buf, 8, BIT(1) | BIT(2));
157	if (err >= 0 && err < 8)
158		err = -EIO;
159	else if (buf[0] == 0x08) /* NOT IMPLEMENTED */
160		err = -ENOSYS;
161	else if (buf[0] == 0x0a) /* REJECTED */
162		err = -EINVAL;
163	else if (buf[0] == 0x0b) /* IN TRANSITION */
164		err = -EAGAIN;
165	if (err < 0)
166		goto end;
167
168	info[0] = buf[4];
169	info[1] = buf[5];
170	info[2] = buf[6];
171	info[3] = buf[7];
172
173	err = 0;
174end:
175	kfree(buf);
176	return err;
177}
178EXPORT_SYMBOL(avc_general_get_plug_info);
179
180static DEFINE_SPINLOCK(transactions_lock);
181static LIST_HEAD(transactions);
182
183enum fcp_state {
184	STATE_PENDING,
185	STATE_BUS_RESET,
186	STATE_COMPLETE,
187	STATE_DEFERRED,
188};
189
190struct fcp_transaction {
191	struct list_head list;
192	struct fw_unit *unit;
193	void *response_buffer;
194	unsigned int response_size;
195	unsigned int response_match_bytes;
196	enum fcp_state state;
197	wait_queue_head_t wait;
198	bool deferrable;
199};
200
201/**
202 * fcp_avc_transaction - send an AV/C command and wait for its response
203 * @unit: a unit on the target device
204 * @command: a buffer containing the command frame; must be DMA-able
205 * @command_size: the size of @command
206 * @response: a buffer for the response frame
207 * @response_size: the maximum size of @response
208 * @response_match_bytes: a bitmap specifying the bytes used to detect the
209 *                        correct response frame
210 *
211 * This function sends a FCP command frame to the target and waits for the
212 * corresponding response frame to be returned.
213 *
214 * Because it is possible for multiple FCP transactions to be active at the
215 * same time, the correct response frame is detected by the value of certain
216 * bytes.  These bytes must be set in @response before calling this function,
217 * and the corresponding bits must be set in @response_match_bytes.
218 *
219 * @command and @response can point to the same buffer.
220 *
221 * Returns the actual size of the response frame, or a negative error code.
222 */
223int fcp_avc_transaction(struct fw_unit *unit,
224			const void *command, unsigned int command_size,
225			void *response, unsigned int response_size,
226			unsigned int response_match_bytes)
227{
228	struct fcp_transaction t;
229	int tcode, ret, tries = 0;
230
231	t.unit = unit;
232	t.response_buffer = response;
233	t.response_size = response_size;
234	t.response_match_bytes = response_match_bytes;
235	t.state = STATE_PENDING;
236	init_waitqueue_head(&t.wait);
237
238	if (*(const u8 *)command == 0x00 || *(const u8 *)command == 0x03)
239		t.deferrable = true;
240
241	spin_lock_irq(&transactions_lock);
242	list_add_tail(&t.list, &transactions);
243	spin_unlock_irq(&transactions_lock);
244
245	for (;;) {
246		tcode = command_size == 4 ? TCODE_WRITE_QUADLET_REQUEST
247					  : TCODE_WRITE_BLOCK_REQUEST;
248		ret = snd_fw_transaction(t.unit, tcode,
249					 CSR_REGISTER_BASE + CSR_FCP_COMMAND,
250					 (void *)command, command_size, 0);
251		if (ret < 0)
252			break;
253deferred:
254		wait_event_timeout(t.wait, t.state != STATE_PENDING,
255				   msecs_to_jiffies(FCP_TIMEOUT_MS));
256
257		if (t.state == STATE_DEFERRED) {
258			/*
259			 * 'AV/C General Specification' define no time limit
260			 * on command completion once an INTERIM response has
261			 * been sent. but we promise to finish this function
262			 * for a caller. Here we use FCP_TIMEOUT_MS for next
263			 * interval. This is not in the specification.
264			 */
265			t.state = STATE_PENDING;
266			goto deferred;
267		} else if (t.state == STATE_COMPLETE) {
268			ret = t.response_size;
269			break;
270		} else if (t.state == STATE_BUS_RESET) {
271			msleep(ERROR_DELAY_MS);
272		} else if (++tries >= ERROR_RETRIES) {
273			dev_err(&t.unit->device, "FCP command timed out\n");
274			ret = -EIO;
275			break;
276		}
277	}
278
279	spin_lock_irq(&transactions_lock);
280	list_del(&t.list);
281	spin_unlock_irq(&transactions_lock);
282
283	return ret;
284}
285EXPORT_SYMBOL(fcp_avc_transaction);
286
287/**
288 * fcp_bus_reset - inform the target handler about a bus reset
289 * @unit: the unit that might be used by fcp_avc_transaction()
290 *
291 * This function must be called from the driver's .update handler to inform
292 * the FCP transaction handler that a bus reset has happened.  Any pending FCP
293 * transactions are retried.
294 */
295void fcp_bus_reset(struct fw_unit *unit)
296{
297	struct fcp_transaction *t;
298
299	spin_lock_irq(&transactions_lock);
300	list_for_each_entry(t, &transactions, list) {
301		if (t->unit == unit &&
302		    (t->state == STATE_PENDING ||
303		     t->state == STATE_DEFERRED)) {
304			t->state = STATE_BUS_RESET;
305			wake_up(&t->wait);
306		}
307	}
308	spin_unlock_irq(&transactions_lock);
309}
310EXPORT_SYMBOL(fcp_bus_reset);
311
312/* checks whether the response matches the masked bytes in response_buffer */
313static bool is_matching_response(struct fcp_transaction *transaction,
314				 const void *response, size_t length)
315{
316	const u8 *p1, *p2;
317	unsigned int mask, i;
318
319	p1 = response;
320	p2 = transaction->response_buffer;
321	mask = transaction->response_match_bytes;
322
323	for (i = 0; ; ++i) {
324		if ((mask & 1) && p1[i] != p2[i])
325			return false;
326		mask >>= 1;
327		if (!mask)
328			return true;
329		if (--length == 0)
330			return false;
331	}
332}
333
334static void fcp_response(struct fw_card *card, struct fw_request *request,
335			 int tcode, int destination, int source,
336			 int generation, unsigned long long offset,
337			 void *data, size_t length, void *callback_data)
338{
339	struct fcp_transaction *t;
340	unsigned long flags;
341
342	if (length < 1 || (*(const u8 *)data & 0xf0) != CTS_AVC)
343		return;
344
345	spin_lock_irqsave(&transactions_lock, flags);
346	list_for_each_entry(t, &transactions, list) {
347		struct fw_device *device = fw_parent_device(t->unit);
348		if (device->card != card ||
349		    device->generation != generation)
350			continue;
351		smp_rmb(); /* node_id vs. generation */
352		if (device->node_id != source)
353			continue;
354
355		if (t->state == STATE_PENDING &&
356		    is_matching_response(t, data, length)) {
357			if (t->deferrable && *(const u8 *)data == 0x0f) {
358				t->state = STATE_DEFERRED;
359			} else {
360				t->state = STATE_COMPLETE;
361				t->response_size = min_t(unsigned int, length,
362							 t->response_size);
363				memcpy(t->response_buffer, data,
364				       t->response_size);
365			}
366			wake_up(&t->wait);
367		}
368	}
369	spin_unlock_irqrestore(&transactions_lock, flags);
370}
371
372static struct fw_address_handler response_register_handler = {
373	.length = 0x200,
374	.address_callback = fcp_response,
375};
376
377static int __init fcp_module_init(void)
378{
379	static const struct fw_address_region response_register_region = {
380		.start = CSR_REGISTER_BASE + CSR_FCP_RESPONSE,
381		.end = CSR_REGISTER_BASE + CSR_FCP_END,
382	};
383
384	fw_core_add_address_handler(&response_register_handler,
385				    &response_register_region);
386
387	return 0;
388}
389
390static void __exit fcp_module_exit(void)
391{
392	WARN_ON(!list_empty(&transactions));
393	fw_core_remove_address_handler(&response_register_handler);
394}
395
396module_init(fcp_module_init);
397module_exit(fcp_module_exit);
398