1/*********************************************************************
2 *
3 * Filename:      toim3232-sir.c
4 * Version:       1.0
5 * Description:   Implementation of dongles based on the Vishay/Temic
6 * 		  TOIM3232 SIR Endec chipset. Currently only the
7 * 		  IRWave IR320ST-2 is tested, although it should work
8 * 		  with any TOIM3232 or TOIM4232 chipset based RS232
9 * 		  dongle with minimal modification.
10 * 		  Based heavily on the Tekram driver (tekram.c),
11 * 		  with thanks to Dag Brattli and Martin Diehl.
12 * Status:        Experimental.
13 * Author:        David Basden <davidb-irda@rcpt.to>
14 * Created at:    Thu Feb 09 23:47:32 2006
15 *
16 *     Copyright (c) 2006 David Basden.
17 *     Copyright (c) 1998-1999 Dag Brattli,
18 *     Copyright (c) 2002 Martin Diehl,
19 *     All Rights Reserved.
20 *
21 *     This program is free software; you can redistribute it and/or
22 *     modify it under the terms of the GNU General Public License as
23 *     published by the Free Software Foundation; either version 2 of
24 *     the License, or (at your option) any later version.
25 *
26 *     Neither Dag Brattli nor University of Tromsø admit liability nor
27 *     provide warranty for any of this software. This material is
28 *     provided "AS-IS" and at no charge.
29 *
30 ********************************************************************/
31
32/*
33 * This driver has currently only been tested on the IRWave IR320ST-2
34 *
35 * PROTOCOL:
36 *
37 * The protocol for talking to the TOIM3232 is quite easy, and is
38 * designed to interface with RS232 with only level convertors. The
39 * BR/~D line on the chip is brought high to signal 'command mode',
40 * where a command byte is sent to select the baudrate of the RS232
41 * interface and the pulse length of the IRDA output. When BR/~D
42 * is brought low, the dongle then changes to the selected baudrate,
43 * and the RS232 interface is used for data until BR/~D is brought
44 * high again. The initial speed for the TOIMx323 after RESET is
45 * 9600 baud.  The baudrate for command-mode is the last selected
46 * baud-rate, or 9600 after a RESET.
47 *
48 * The  dongle I have (below) adds some extra hardware on the front end,
49 * but this is mostly directed towards pariasitic power from the RS232
50 * line rather than changing very much about how to communicate with
51 * the TOIM3232.
52 *
53 * The protocol to talk to the TOIM4232 chipset seems to be almost
54 * identical to the TOIM3232 (and the 4232 datasheet is more detailed)
55 * so this code will probably work on that as well, although I haven't
56 * tested it on that hardware.
57 *
58 * Target dongle variations that might be common:
59 *
60 * DTR and RTS function:
61 *   The data sheet for the 4232 has a sample implementation that hooks the
62 *   DTR and RTS lines to the RESET and BaudRate/~Data lines of the
63 *   chip (through line-converters). Given both DTR and RTS would have to
64 *   be held low in normal operation, and the TOIMx232 requires +5V to
65 *   signal ground, most dongle designers would almost certainly choose
66 *   an implementation that kept at least one of DTR or RTS high in
67 *   normal operation to provide power to the dongle, but will likely
68 *   vary between designs.
69 *
70 * User specified command bits:
71 *  There are two user-controllable output lines from the TOIMx232 that
72 *  can be set low or high by setting the appropriate bits in the
73 *  high-nibble of the command byte (when setting speed and pulse length).
74 *  These might be used to switch on and off added hardware or extra
75 *  dongle features.
76 *
77 *
78 * Target hardware: IRWave IR320ST-2
79 *
80 * 	The IRWave IR320ST-2 is a simple dongle based on the Vishay/Temic
81 * 	TOIM3232 SIR Endec and the Vishay/Temic TFDS4500 SIR IRDA transceiver.
82 * 	It uses a hex inverter and some discrete components to buffer and
83 * 	line convert the RS232 down to 5V.
84 *
85 * 	The dongle is powered through a voltage regulator, fed by a large
86 * 	capacitor. To switch the dongle on, DTR is brought high to charge
87 * 	the capacitor and drive the voltage regulator. DTR isn't associated
88 * 	with any control lines on the TOIM3232. Parisitic power is also taken
89 * 	from the RTS, TD and RD lines when brought high, but through resistors.
90 * 	When DTR is low, the circuit might lose power even with RTS high.
91 *
92 * 	RTS is inverted and attached to the BR/~D input pin. When RTS
93 * 	is high, BR/~D is low, and the TOIM3232 is in the normal 'data' mode.
94 * 	RTS is brought low, BR/~D is high, and the TOIM3232 is in 'command
95 * 	mode'.
96 *
97 * 	For some unknown reason, the RESET line isn't actually connected
98 * 	to anything. This means to reset the dongle to get it to a known
99 * 	state (9600 baud) you must drop DTR and RTS low, wait for the power
100 * 	capacitor to discharge, and then bring DTR (and RTS for data mode)
101 * 	high again, and wait for the capacitor to charge, the power supply
102 * 	to stabilise, and the oscillator clock to stabilise.
103 *
104 * 	Fortunately, if the current baudrate is known, the chipset can
105 * 	easily change speed by entering command mode without having to
106 * 	reset the dongle first.
107 *
108 * 	Major Components:
109 *
110 * 	- Vishay/Temic TOIM3232 SIR Endec to change RS232 pulse timings
111 * 	  to IRDA pulse timings
112 * 	- 3.6864MHz crystal to drive TOIM3232 clock oscillator
113 * 	- DM74lS04M Inverting Hex line buffer for RS232 input buffering
114 * 	  and level conversion
115 * 	- PJ2951AC 150mA voltage regulator
116 * 	- Vishay/Temic TFDS4500	SIR IRDA front-end transceiver
117 *
118 */
119
120#include <linux/module.h>
121#include <linux/delay.h>
122#include <linux/init.h>
123#include <linux/sched.h>
124
125#include <net/irda/irda.h>
126
127#include "sir-dev.h"
128
129static int toim3232delay = 150;	/* default is 150 ms */
130module_param(toim3232delay, int, 0);
131MODULE_PARM_DESC(toim3232delay, "toim3232 dongle write complete delay");
132
133#if 0
134static int toim3232flipdtr = 0;	/* default is DTR high to reset */
135module_param(toim3232flipdtr, int, 0);
136MODULE_PARM_DESC(toim3232flipdtr, "toim3232 dongle invert DTR (Reset)");
137
138static int toim3232fliprts = 0;	/* default is RTS high for baud change */
139module_param(toim3232fliptrs, int, 0);
140MODULE_PARM_DESC(toim3232fliprts, "toim3232 dongle invert RTS (BR/D)");
141#endif
142
143static int toim3232_open(struct sir_dev *);
144static int toim3232_close(struct sir_dev *);
145static int toim3232_change_speed(struct sir_dev *, unsigned);
146static int toim3232_reset(struct sir_dev *);
147
148#define TOIM3232_115200 0x00
149#define TOIM3232_57600  0x01
150#define TOIM3232_38400  0x02
151#define TOIM3232_19200  0x03
152#define TOIM3232_9600   0x06
153#define TOIM3232_2400   0x0A
154
155#define TOIM3232_PW     0x10 /* Pulse select bit */
156
157static struct dongle_driver toim3232 = {
158	.owner		= THIS_MODULE,
159	.driver_name	= "Vishay TOIM3232",
160	.type		= IRDA_TOIM3232_DONGLE,
161	.open		= toim3232_open,
162	.close		= toim3232_close,
163	.reset		= toim3232_reset,
164	.set_speed	= toim3232_change_speed,
165};
166
167static int __init toim3232_sir_init(void)
168{
169	if (toim3232delay < 1  ||  toim3232delay > 500)
170		toim3232delay = 200;
171	pr_debug("%s - using %d ms delay\n",
172		 toim3232.driver_name, toim3232delay);
173	return irda_register_dongle(&toim3232);
174}
175
176static void __exit toim3232_sir_cleanup(void)
177{
178	irda_unregister_dongle(&toim3232);
179}
180
181static int toim3232_open(struct sir_dev *dev)
182{
183	struct qos_info *qos = &dev->qos;
184
185	/* Pull the lines high to start with.
186	 *
187	 * For the IR320ST-2, we need to charge the main supply capacitor to
188	 * switch the device on. We keep DTR high throughout to do this.
189	 * When RTS, TD and RD are high, they will also trickle-charge the
190	 * cap. RTS is high for data transmission, and low for baud rate select.
191	 * 	-- DGB
192	 */
193	sirdev_set_dtr_rts(dev, TRUE, TRUE);
194
195	/* The TOI3232 supports many speeds between 1200bps and 115000bps.
196	 * We really only care about those supported by the IRDA spec, but
197	 * 38400 seems to be implemented in many places */
198	qos->baud_rate.bits &= IR_2400|IR_9600|IR_19200|IR_38400|IR_57600|IR_115200;
199
200	/* From the tekram driver. Not sure what a reasonable value is -- DGB */
201	qos->min_turn_time.bits = 0x01; /* Needs at least 10 ms */
202	irda_qos_bits_to_value(qos);
203
204	/* irda thread waits 50 msec for power settling */
205
206	return 0;
207}
208
209static int toim3232_close(struct sir_dev *dev)
210{
211	/* Power off dongle */
212	sirdev_set_dtr_rts(dev, FALSE, FALSE);
213
214	return 0;
215}
216
217/*
218 * Function toim3232change_speed (dev, state, speed)
219 *
220 *    Set the speed for the TOIM3232 based dongle. Warning, this
221 *    function must be called with a process context!
222 *
223 *    Algorithm
224 *    1. keep DTR high but clear RTS to bring into baud programming mode
225 *    2. wait at least 7us to enter programming mode
226 *    3. send control word to set baud rate and timing
227 *    4. wait at least 1us
228 *    5. bring RTS high to enter DATA mode (RS232 is passed through to transceiver)
229 *    6. should take effect immediately (although probably worth waiting)
230 */
231
232#define TOIM3232_STATE_WAIT_SPEED	(SIRDEV_STATE_DONGLE_SPEED + 1)
233
234static int toim3232_change_speed(struct sir_dev *dev, unsigned speed)
235{
236	unsigned state = dev->fsm.substate;
237	unsigned delay = 0;
238	u8 byte;
239	static int ret = 0;
240
241	switch(state) {
242	case SIRDEV_STATE_DONGLE_SPEED:
243
244		/* Figure out what we are going to send as a control byte */
245		switch (speed) {
246		case 2400:
247			byte = TOIM3232_PW|TOIM3232_2400;
248			break;
249		default:
250			speed = 9600;
251			ret = -EINVAL;
252			/* fall thru */
253		case 9600:
254			byte = TOIM3232_PW|TOIM3232_9600;
255			break;
256		case 19200:
257			byte = TOIM3232_PW|TOIM3232_19200;
258			break;
259		case 38400:
260			byte = TOIM3232_PW|TOIM3232_38400;
261			break;
262		case 57600:
263			byte = TOIM3232_PW|TOIM3232_57600;
264			break;
265		case 115200:
266			byte = TOIM3232_115200;
267			break;
268		}
269
270		/* Set DTR, Clear RTS: Go into baud programming mode */
271		sirdev_set_dtr_rts(dev, TRUE, FALSE);
272
273		/* Wait at least 7us */
274		udelay(14);
275
276		/* Write control byte */
277		sirdev_raw_write(dev, &byte, 1);
278
279		dev->speed = speed;
280
281		state = TOIM3232_STATE_WAIT_SPEED;
282		delay = toim3232delay;
283		break;
284
285	case TOIM3232_STATE_WAIT_SPEED:
286		/* Have transmitted control byte * Wait for 'at least 1us' */
287		udelay(14);
288
289		/* Set DTR, Set RTS: Go into normal data mode */
290		sirdev_set_dtr_rts(dev, TRUE, TRUE);
291
292		/* Wait (TODO: check this is needed) */
293		udelay(50);
294		break;
295
296	default:
297		printk(KERN_ERR "%s - undefined state %d\n", __func__, state);
298		ret = -EINVAL;
299		break;
300	}
301
302	dev->fsm.substate = state;
303	return (delay > 0) ? delay : ret;
304}
305
306/*
307 * Function toim3232reset (driver)
308 *
309 *      This function resets the toim3232 dongle. Warning, this function
310 *      must be called with a process context!!
311 *
312 * What we should do is:
313 * 	0. Pull RESET high
314 * 	1. Wait for at least 7us
315 * 	2. Pull RESET low
316 * 	3. Wait for at least 7us
317 * 	4. Pull BR/~D high
318 * 	5. Wait for at least 7us
319 * 	6. Send control byte to set baud rate
320 * 	7. Wait at least 1us after stop bit
321 * 	8. Pull BR/~D low
322 * 	9. Should then be in data mode
323 *
324 * Because the IR320ST-2 doesn't have the RESET line connected for some reason,
325 * we'll have to do something else.
326 *
327 * The default speed after a RESET is 9600, so lets try just bringing it up in
328 * data mode after switching it off, waiting for the supply capacitor to
329 * discharge, and then switch it back on. This isn't actually pulling RESET
330 * high, but it seems to have the same effect.
331 *
332 * This behaviour will probably work on dongles that have the RESET line connected,
333 * but if not, add a flag for the IR320ST-2, and implment the above-listed proper
334 * behaviour.
335 *
336 * RTS is inverted and then fed to BR/~D, so to put it in programming mode, we
337 * need to have pull RTS low
338 */
339
340static int toim3232_reset(struct sir_dev *dev)
341{
342	/* Switch off both DTR and RTS to switch off dongle */
343	sirdev_set_dtr_rts(dev, FALSE, FALSE);
344
345	/* Should sleep a while. This might be evil doing it this way.*/
346	set_current_state(TASK_UNINTERRUPTIBLE);
347	schedule_timeout(msecs_to_jiffies(50));
348
349	/* Set DTR, Set RTS (data mode) */
350	sirdev_set_dtr_rts(dev, TRUE, TRUE);
351
352	/* Wait at least 10 ms for power to stabilize again */
353	set_current_state(TASK_UNINTERRUPTIBLE);
354	schedule_timeout(msecs_to_jiffies(10));
355
356	/* Speed should now be 9600 */
357	dev->speed = 9600;
358
359	return 0;
360}
361
362MODULE_AUTHOR("David Basden <davidb-linux@rcpt.to>");
363MODULE_DESCRIPTION("Vishay/Temic TOIM3232 based dongle driver");
364MODULE_LICENSE("GPL");
365MODULE_ALIAS("irda-dongle-12"); /* IRDA_TOIM3232_DONGLE */
366
367module_init(toim3232_sir_init);
368module_exit(toim3232_sir_cleanup);
369