1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * IR SIR driver, (C) 2000 Milan Pikula <www@fornax.sk>
4 *
5 * sir_ir - Device driver for use with SIR (serial infra red)
6 * mode of IrDA on many notebooks.
7 */
8
9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11#include <linux/module.h>
12#include <linux/interrupt.h>
13#include <linux/kernel.h>
14#include <linux/serial_reg.h>
15#include <linux/ktime.h>
16#include <linux/delay.h>
17#include <linux/platform_device.h>
18
19#include <media/rc-core.h>
20
21/* SECTION: Definitions */
22#define PULSE '['
23
24/* 9bit * 1s/115200bit in milli seconds = 78.125ms*/
25#define TIME_CONST (9000000ul / 115200ul)
26
27/* timeout for sequences in jiffies (=5/100s), must be longer than TIME_CONST */
28#define SIR_TIMEOUT	(HZ * 5 / 100)
29
30/* onboard sir ports are typically com3 */
31static int io = 0x3e8;
32static int irq = 4;
33static int threshold = 3;
34
35static DEFINE_SPINLOCK(timer_lock);
36static struct timer_list timerlist;
37/* time of last signal change detected */
38static ktime_t last;
39/* time of last UART data ready interrupt */
40static ktime_t last_intr_time;
41static int last_value;
42static struct rc_dev *rcdev;
43
44static struct platform_device *sir_ir_dev;
45
46static DEFINE_SPINLOCK(hardware_lock);
47
48/* SECTION: Prototypes */
49
50/* Communication with user-space */
51static void add_read_queue(int flag, unsigned long val);
52/* Hardware */
53static irqreturn_t sir_interrupt(int irq, void *dev_id);
54static void send_space(unsigned long len);
55static void send_pulse(unsigned long len);
56static int init_hardware(void);
57static void drop_hardware(void);
58/* Initialisation */
59
60static inline unsigned int sinp(int offset)
61{
62	return inb(io + offset);
63}
64
65static inline void soutp(int offset, int value)
66{
67	outb(value, io + offset);
68}
69
70/* SECTION: Communication with user-space */
71static int sir_tx_ir(struct rc_dev *dev, unsigned int *tx_buf,
72		     unsigned int count)
73{
74	unsigned long flags;
75	int i;
76
77	local_irq_save(flags);
78	for (i = 0; i < count;) {
79		if (tx_buf[i])
80			send_pulse(tx_buf[i]);
81		i++;
82		if (i >= count)
83			break;
84		if (tx_buf[i])
85			send_space(tx_buf[i]);
86		i++;
87	}
88	local_irq_restore(flags);
89
90	return count;
91}
92
93static void add_read_queue(int flag, unsigned long val)
94{
95	struct ir_raw_event ev = {};
96
97	pr_debug("add flag %d with val %lu\n", flag, val);
98
99	/*
100	 * statistically, pulses are ~TIME_CONST/2 too long. we could
101	 * maybe make this more exact, but this is good enough
102	 */
103	if (flag) {
104		/* pulse */
105		if (val > TIME_CONST / 2)
106			val -= TIME_CONST / 2;
107		else /* should not ever happen */
108			val = 1;
109		ev.pulse = true;
110	} else {
111		val += TIME_CONST / 2;
112	}
113	ev.duration = val;
114
115	ir_raw_event_store_with_filter(rcdev, &ev);
116}
117
118/* SECTION: Hardware */
119static void sir_timeout(struct timer_list *unused)
120{
121	/*
122	 * if last received signal was a pulse, but receiving stopped
123	 * within the 9 bit frame, we need to finish this pulse and
124	 * simulate a signal change to from pulse to space. Otherwise
125	 * upper layers will receive two sequences next time.
126	 */
127
128	unsigned long flags;
129	unsigned long pulse_end;
130
131	/* avoid interference with interrupt */
132	spin_lock_irqsave(&timer_lock, flags);
133	if (last_value) {
134		/* clear unread bits in UART and restart */
135		outb(UART_FCR_CLEAR_RCVR, io + UART_FCR);
136		/* determine 'virtual' pulse end: */
137		pulse_end = min_t(unsigned long,
138				  ktime_us_delta(last, last_intr_time),
139				  IR_MAX_DURATION);
140		dev_dbg(&sir_ir_dev->dev, "timeout add %d for %lu usec\n",
141			last_value, pulse_end);
142		add_read_queue(last_value, pulse_end);
143		last_value = 0;
144		last = last_intr_time;
145	}
146	spin_unlock_irqrestore(&timer_lock, flags);
147	ir_raw_event_handle(rcdev);
148}
149
150static irqreturn_t sir_interrupt(int irq, void *dev_id)
151{
152	unsigned char data;
153	ktime_t curr_time;
154	unsigned long delt;
155	unsigned long deltintr;
156	unsigned long flags;
157	int counter = 0;
158	int iir, lsr;
159
160	while ((iir = inb(io + UART_IIR) & UART_IIR_ID)) {
161		if (++counter > 256) {
162			dev_err(&sir_ir_dev->dev, "Trapped in interrupt");
163			break;
164		}
165
166		switch (iir & UART_IIR_ID) { /* FIXME toto treba preriedit */
167		case UART_IIR_MSI:
168			(void)inb(io + UART_MSR);
169			break;
170		case UART_IIR_RLSI:
171		case UART_IIR_THRI:
172			(void)inb(io + UART_LSR);
173			break;
174		case UART_IIR_RDI:
175			/* avoid interference with timer */
176			spin_lock_irqsave(&timer_lock, flags);
177			do {
178				del_timer(&timerlist);
179				data = inb(io + UART_RX);
180				curr_time = ktime_get();
181				delt = min_t(unsigned long,
182					     ktime_us_delta(last, curr_time),
183					     IR_MAX_DURATION);
184				deltintr = min_t(unsigned long,
185						 ktime_us_delta(last_intr_time,
186								curr_time),
187						 IR_MAX_DURATION);
188				dev_dbg(&sir_ir_dev->dev, "t %lu, d %d\n",
189					deltintr, (int)data);
190				/*
191				 * if nothing came in last X cycles,
192				 * it was gap
193				 */
194				if (deltintr > TIME_CONST * threshold) {
195					if (last_value) {
196						dev_dbg(&sir_ir_dev->dev, "GAP\n");
197						/* simulate signal change */
198						add_read_queue(last_value,
199							       delt -
200							       deltintr);
201						last_value = 0;
202						last = last_intr_time;
203						delt = deltintr;
204					}
205				}
206				data = 1;
207				if (data ^ last_value) {
208					/*
209					 * deltintr > 2*TIME_CONST, remember?
210					 * the other case is timeout
211					 */
212					add_read_queue(last_value,
213						       delt - TIME_CONST);
214					last_value = data;
215					last = curr_time;
216					last = ktime_sub_us(last,
217							    TIME_CONST);
218				}
219				last_intr_time = curr_time;
220				if (data) {
221					/*
222					 * start timer for end of
223					 * sequence detection
224					 */
225					timerlist.expires = jiffies +
226								SIR_TIMEOUT;
227					add_timer(&timerlist);
228				}
229
230				lsr = inb(io + UART_LSR);
231			} while (lsr & UART_LSR_DR); /* data ready */
232			spin_unlock_irqrestore(&timer_lock, flags);
233			break;
234		default:
235			break;
236		}
237	}
238	ir_raw_event_handle(rcdev);
239	return IRQ_RETVAL(IRQ_HANDLED);
240}
241
242static void send_space(unsigned long len)
243{
244	usleep_range(len, len + 25);
245}
246
247static void send_pulse(unsigned long len)
248{
249	long bytes_out = len / TIME_CONST;
250
251	if (bytes_out == 0)
252		bytes_out++;
253
254	while (bytes_out--) {
255		outb(PULSE, io + UART_TX);
256		/* FIXME treba seriozne cakanie z char/serial.c */
257		while (!(inb(io + UART_LSR) & UART_LSR_THRE))
258			;
259	}
260}
261
262static int init_hardware(void)
263{
264	u8 scratch, scratch2, scratch3;
265	unsigned long flags;
266
267	spin_lock_irqsave(&hardware_lock, flags);
268
269	/*
270	 * This is a simple port existence test, borrowed from the autoconfig
271	 * function in drivers/tty/serial/8250/8250_port.c
272	 */
273	scratch = sinp(UART_IER);
274	soutp(UART_IER, 0);
275#ifdef __i386__
276	outb(0xff, 0x080);
277#endif
278	scratch2 = sinp(UART_IER) & 0x0f;
279	soutp(UART_IER, 0x0f);
280#ifdef __i386__
281	outb(0x00, 0x080);
282#endif
283	scratch3 = sinp(UART_IER) & 0x0f;
284	soutp(UART_IER, scratch);
285	if (scratch2 != 0 || scratch3 != 0x0f) {
286		/* we fail, there's nothing here */
287		spin_unlock_irqrestore(&hardware_lock, flags);
288		pr_err("port existence test failed, cannot continue\n");
289		return -ENODEV;
290	}
291
292	/* reset UART */
293	outb(0, io + UART_MCR);
294	outb(0, io + UART_IER);
295	/* init UART */
296	/* set DLAB, speed = 115200 */
297	outb(UART_LCR_DLAB | UART_LCR_WLEN7, io + UART_LCR);
298	outb(1, io + UART_DLL); outb(0, io + UART_DLM);
299	/* 7N1+start = 9 bits at 115200 ~ 3 bits at 44000 */
300	outb(UART_LCR_WLEN7, io + UART_LCR);
301	/* FIFO operation */
302	outb(UART_FCR_ENABLE_FIFO, io + UART_FCR);
303	/* interrupts */
304	/* outb(UART_IER_RLSI|UART_IER_RDI|UART_IER_THRI, io + UART_IER); */
305	outb(UART_IER_RDI, io + UART_IER);
306	/* turn on UART */
307	outb(UART_MCR_DTR | UART_MCR_RTS | UART_MCR_OUT2, io + UART_MCR);
308	spin_unlock_irqrestore(&hardware_lock, flags);
309
310	return 0;
311}
312
313static void drop_hardware(void)
314{
315	unsigned long flags;
316
317	spin_lock_irqsave(&hardware_lock, flags);
318
319	/* turn off interrupts */
320	outb(0, io + UART_IER);
321
322	spin_unlock_irqrestore(&hardware_lock, flags);
323}
324
325/* SECTION: Initialisation */
326static int sir_ir_probe(struct platform_device *dev)
327{
328	int retval;
329
330	rcdev = devm_rc_allocate_device(&sir_ir_dev->dev, RC_DRIVER_IR_RAW);
331	if (!rcdev)
332		return -ENOMEM;
333
334	rcdev->device_name = "SIR IrDA port";
335	rcdev->input_phys = KBUILD_MODNAME "/input0";
336	rcdev->input_id.bustype = BUS_HOST;
337	rcdev->input_id.vendor = 0x0001;
338	rcdev->input_id.product = 0x0001;
339	rcdev->input_id.version = 0x0100;
340	rcdev->tx_ir = sir_tx_ir;
341	rcdev->allowed_protocols = RC_PROTO_BIT_ALL_IR_DECODER;
342	rcdev->driver_name = KBUILD_MODNAME;
343	rcdev->map_name = RC_MAP_RC6_MCE;
344	rcdev->timeout = IR_DEFAULT_TIMEOUT;
345	rcdev->dev.parent = &sir_ir_dev->dev;
346
347	timer_setup(&timerlist, sir_timeout, 0);
348
349	/* get I/O port access and IRQ line */
350	if (!devm_request_region(&sir_ir_dev->dev, io, 8, KBUILD_MODNAME)) {
351		pr_err("i/o port 0x%.4x already in use.\n", io);
352		return -EBUSY;
353	}
354	retval = devm_request_irq(&sir_ir_dev->dev, irq, sir_interrupt, 0,
355				  KBUILD_MODNAME, NULL);
356	if (retval < 0) {
357		pr_err("IRQ %d already in use.\n", irq);
358		return retval;
359	}
360
361	retval = init_hardware();
362	if (retval) {
363		del_timer_sync(&timerlist);
364		return retval;
365	}
366
367	pr_info("I/O port 0x%.4x, IRQ %d.\n", io, irq);
368
369	retval = devm_rc_register_device(&sir_ir_dev->dev, rcdev);
370	if (retval < 0)
371		return retval;
372
373	return 0;
374}
375
376static int sir_ir_remove(struct platform_device *dev)
377{
378	drop_hardware();
379	del_timer_sync(&timerlist);
380	return 0;
381}
382
383static struct platform_driver sir_ir_driver = {
384	.probe		= sir_ir_probe,
385	.remove		= sir_ir_remove,
386	.driver		= {
387		.name	= "sir_ir",
388	},
389};
390
391static int __init sir_ir_init(void)
392{
393	int retval;
394
395	retval = platform_driver_register(&sir_ir_driver);
396	if (retval)
397		return retval;
398
399	sir_ir_dev = platform_device_alloc("sir_ir", 0);
400	if (!sir_ir_dev) {
401		retval = -ENOMEM;
402		goto pdev_alloc_fail;
403	}
404
405	retval = platform_device_add(sir_ir_dev);
406	if (retval)
407		goto pdev_add_fail;
408
409	return 0;
410
411pdev_add_fail:
412	platform_device_put(sir_ir_dev);
413pdev_alloc_fail:
414	platform_driver_unregister(&sir_ir_driver);
415	return retval;
416}
417
418static void __exit sir_ir_exit(void)
419{
420	platform_device_unregister(sir_ir_dev);
421	platform_driver_unregister(&sir_ir_driver);
422}
423
424module_init(sir_ir_init);
425module_exit(sir_ir_exit);
426
427MODULE_DESCRIPTION("Infrared receiver driver for SIR type serial ports");
428MODULE_AUTHOR("Milan Pikula");
429MODULE_LICENSE("GPL");
430
431module_param_hw(io, int, ioport, 0444);
432MODULE_PARM_DESC(io, "I/O address base (0x3f8 or 0x2f8)");
433
434module_param_hw(irq, int, irq, 0444);
435MODULE_PARM_DESC(irq, "Interrupt (4 or 3)");
436
437module_param(threshold, int, 0444);
438MODULE_PARM_DESC(threshold, "space detection threshold (3)");
439