Input: add joystick driver for Walkera WK-0701 RC transmitter

Signed-off-by: Peter Popovec <popovec@fei.tuke.sk> Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

Input: add joystick driver for Walkera WK-0701 RC transmitter
Signed-off-by: Peter Popovec <popovec@fei.tuke.sk> Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Peter Popovec · Dmitry Torokhov
1 parent 59bdb43769
Showing 4 changed files with 414 additions and 0 deletions Side-by-side Diff
Documentation/input/walkera0701.txt
drivers/input/joystick/Kconfig
drivers/input/joystick/Makefile
drivers/input/joystick/walkera0701.c
+
+Walkera WK-0701 transmitter is supplied with a ready to fly Walkera
+helicopters such as HM36, HM37, HM60. The walkera0701 module enables to use
+this transmitter as joystick
+
+Devel homepage and download:
+http://zub.fei.tuke.sk/walkera-wk0701/
+
+or use cogito:
+cg-clone http://zub.fei.tuke.sk/GIT/walkera0701-joystick
+
+
+Connecting to PC:
+
+At back side of transmitter S-video connector can be found. Modulation
+pulses from processor to HF part can be found at pin 2 of this connector,
+pin 3 is GND. Between pin 3 and CPU 5k6 resistor can be found. To get
+modulation pulses to PC, signal pulses must be amplified.
+
+Cable: (walkera TX to parport)
+
+Walkera WK-0701 TX S-VIDEO connector:
+ (back side of TX)
+     __   __              S-video:                                  canon25
+    /  |_|  \             pin 2 (signal)              NPN           parport
+   / O 4 3 O \            pin 3 (GND)        LED        ________________  10 ACK
+  ( O 2   1 O )                                         | C
+   \   ___   /      2 ________________________|\|_____|/
+    | [___] |                                 |/|   B |\
+     -------        3 __________________________________|________________ 25 GND
+                                                          E
+
+
+I use green LED and BC109 NPN transistor.
+
+Software:
+
+Build kernel with walkera0701 module. Module walkera0701 need exclusive
+access to parport, modules like lp must be unloaded before loading
+walkera0701 module, check dmesg for error messages. Connect TX to PC by
+cable and run jstest /dev/input/js0 to see values from TX. If no value can
+be changed by TX "joystick", check output from /proc/interrupts. Value for
+(usually irq7) parport must increase if TX is on.
+
+
+
+Technical details:
+
+Driver use interrupt from parport ACK input bit to measure pulse length
+using hrtimers.
+
+Frame format:
+Based on walkera WK-0701 PCM Format description by Shaul Eizikovich.
+(downloaded from http://www.smartpropoplus.com/Docs/Walkera_Wk-0701_PCM.pdf)
+
+Signal pulses:
+                   (ANALOG)
+    SYNC      BIN   OCT
+  +---------+      +------+
+  |         |      |      |
+--+         +------+      +---
+
+Frame:
+ SYNC , BIN1, OCT1, BIN2, OCT2 ... BIN24, OCT24, BIN25, next frame SYNC ..
+
+pulse length:
+   Binary values:		Analog octal values:
+
+   288 uS Binary 0		318 uS       000
+   438 uS Binary 1		398 uS       001
+				478 uS       010
+				558 uS       011
+				638 uS       100
+  1306 uS SYNC			718 uS       101
+				798 uS       110
+				878 uS       111
+
+24 bin+oct values + 1 bin value = 24*4+1 bits  = 97 bits
+
+(Warning, pulses on ACK ar inverted by transistor, irq is rised up on sync
+to bin change or octal value to bin change).
+
+Binary data representations:
+
+One binary and octal value can be grouped to nibble. 24 nibbles + one binary
+values can be sampled between sync pulses.
+
+Values for first four channels (analog joystick values) can be found in
+first 10 nibbles. Analog value is represented by one sign bit and 9 bit
+absolute binary value. (10 bits per channel). Next nibble is checksum for
+first ten nibbles.
+
+Next nibbles 12 .. 21 represents four channels (not all channels can be
+directly controlled from TX). Binary representations ar the same as in first
+four channels. In nibbles 22 and 23 is a special magic number. Nibble 24 is
+checksum for nibbles 12..23.
+
+After last octal value for nibble 24 and next sync pulse one additional
+binary value can be sampled. This bit and magic number is not used in
+software driver. Some details about this magic numbers can be found in
+Walkera_Wk-0701_PCM.pdf.
+
+Checksum calculation:
+
+Summary of octal values in nibbles must be same as octal value in checksum
+nibble (only first 3 bits are used). Binary value for checksum nibble is
+calculated by sum of binary values in checked nibbles + sum of octal values
+in checked nibbles divided by 8. Only bit 0 of this sum is used.
@@ -294,5 +294,17 @@
 	  This option enables support for the LED which surrounds the Big X on
 	  XBox 360 controller.
  
+config JOYSTICK_WALKERA0701
+	tristate "Walkera WK-0701 RC transmitter"
+	depends on HIGH_RES_TIMERS && PARPORT
+	help
+	  Say Y or M here if you have a Walkera WK-0701 transmitter which is
+	  supplied with a ready to fly Walkera helicopters such as HM36,
+	  HM37, HM60 and want to use it via parport as a joystick. More
+	  information is available: <file:Documentation/input/walkera0701.txt>
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called walkera0701.
+
 endif
@@ -29,4 +29,5 @@
 obj-$(CONFIG_JOYSTICK_WARRIOR)		+= warrior.o
 obj-$(CONFIG_JOYSTICK_XPAD)		+= xpad.o
 obj-$(CONFIG_JOYSTICK_ZHENHUA)		+= zhenhua.o
+obj-$(CONFIG_JOYSTICK_WALKERA0701)	+= walkera0701.o
+/*
+ *  Parallel port to Walkera WK-0701 TX joystick
+ *
+ *  Copyright (c) 2008 Peter Popovec
+ *
+ *  More about driver:  <file:Documentation/input/walkera0701.txt>
+ */
+
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+*/
+
+/* #define WK0701_DEBUG */
+
+#define RESERVE 20000
+#define SYNC_PULSE 1306000
+#define BIN0_PULSE 288000
+#define BIN1_PULSE 438000
+
+#define ANALOG_MIN_PULSE 318000
+#define ANALOG_MAX_PULSE 878000
+#define ANALOG_DELTA 80000
+
+#define BIN_SAMPLE ((BIN0_PULSE + BIN1_PULSE) / 2)
+
+#define NO_SYNC 25
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/parport.h>
+#include <linux/input.h>
+#include <linux/hrtimer.h>
+
+MODULE_AUTHOR("Peter Popovec <popovec@fei.tuke.sk>");
+MODULE_DESCRIPTION("Walkera WK-0701 TX as joystick");
+MODULE_LICENSE("GPL");
+
+static unsigned int walkera0701_pp_no;
+module_param_named(port, walkera0701_pp_no, int, 0);
+MODULE_PARM_DESC(port,
+		 "Parallel port adapter for Walkera WK-0701 TX (default is 0)");
+
+/*
+ * For now, only one device is supported, if somebody need more devices, code
+ * can be expanded, one struct walkera_dev per device must be allocated and
+ * set up by walkera0701_connect (release of device by walkera0701_disconnect)
+ */
+
+struct walkera_dev {
+	unsigned char buf[25];
+	u64 irq_time, irq_lasttime;
+	int counter;
+	int ack;
+
+	struct input_dev *input_dev;
+	struct hrtimer timer;
+
+	struct parport *parport;
+	struct pardevice *pardevice;
+};
+
+static struct walkera_dev w_dev;
+
+static inline void walkera0701_parse_frame(struct walkera_dev *w)
+{
+	int i;
+	int val1, val2, val3, val4, val5, val6, val7, val8;
+	int crc1, crc2;
+
+	for (crc1 = crc2 = i = 0; i < 10; i++) {
+		crc1 += w->buf[i] & 7;
+		crc2 += (w->buf[i] & 8) >> 3;
+	}
+	if ((w->buf[10] & 7) != (crc1 & 7))
+		return;
+	if (((w->buf[10] & 8) >> 3) != (((crc1 >> 3) + crc2) & 1))
+		return;
+	for (crc1 = crc2 = 0, i = 11; i < 23; i++) {
+		crc1 += w->buf[i] & 7;
+		crc2 += (w->buf[i] & 8) >> 3;
+	}
+	if ((w->buf[23] & 7) != (crc1 & 7))
+		return;
+	if (((w->buf[23] & 8) >> 3) != (((crc1 >> 3) + crc2) & 1))
+		return;
+	val1 = ((w->buf[0] & 7) * 256 + w->buf[1] * 16 + w->buf[2]) >> 2;
+	val1 *= ((w->buf[0] >> 2) & 2) - 1;	/* sign */
+	val2 = (w->buf[2] & 1) << 8 | (w->buf[3] << 4) | w->buf[4];
+	val2 *= (w->buf[2] & 2) - 1;	/* sign */
+	val3 = ((w->buf[5] & 7) * 256 + w->buf[6] * 16 + w->buf[7]) >> 2;
+	val3 *= ((w->buf[5] >> 2) & 2) - 1;	/* sign */
+	val4 = (w->buf[7] & 1) << 8 | (w->buf[8] << 4) | w->buf[9];
+	val4 *= (w->buf[7] & 2) - 1;	/* sign */
+	val5 = ((w->buf[11] & 7) * 256 + w->buf[12] * 16 + w->buf[13]) >> 2;
+	val5 *= ((w->buf[11] >> 2) & 2) - 1;	/* sign */
+	val6 = (w->buf[13] & 1) << 8 | (w->buf[14] << 4) | w->buf[15];
+	val6 *= (w->buf[13] & 2) - 1;	/* sign */
+	val7 = ((w->buf[16] & 7) * 256 + w->buf[17] * 16 + w->buf[18]) >> 2;
+	val7 *= ((w->buf[16] >> 2) & 2) - 1;	/*sign */
+	val8 = (w->buf[18] & 1) << 8 | (w->buf[19] << 4) | w->buf[20];
+	val8 *= (w->buf[18] & 2) - 1;	/*sign */
+
+#ifdef WK0701_DEBUG
+	{
+		int magic, magic_bit;
+		magic = (w->buf[21] << 4) | w->buf[22];
+		magic_bit = (w->buf[24] & 8) >> 3;
+		printk(KERN_DEBUG
+		       "walkera0701: %4d %4d %4d %4d  %4d %4d %4d %4d (magic %2x %d)\n",
+		       val1, val2, val3, val4, val5, val6, val7, val8, magic,
+		       magic_bit);
+	}
+#endif
+	input_report_abs(w->input_dev, ABS_X, val2);
+	input_report_abs(w->input_dev, ABS_Y, val1);
+	input_report_abs(w->input_dev, ABS_Z, val6);
+	input_report_abs(w->input_dev, ABS_THROTTLE, val3);
+	input_report_abs(w->input_dev, ABS_RUDDER, val4);
+	input_report_abs(w->input_dev, ABS_MISC, val7);
+	input_report_key(w->input_dev, BTN_GEAR_DOWN, val5 > 0);
+}
+
+static inline int read_ack(struct pardevice *p)
+{
+	return parport_read_status(p->port) & 0x40;
+}
+
+/* falling edge, prepare to BIN value calculation */
+static void walkera0701_irq_handler(void *handler_data)
+{
+	u64 pulse_time;
+	struct walkera_dev *w = handler_data;
+
+	w->irq_time = ktime_to_ns(ktime_get());
+	pulse_time = w->irq_time - w->irq_lasttime;
+	w->irq_lasttime = w->irq_time;
+
+	/* cancel timer, if in handler or active do resync */
+	if (unlikely(0 != hrtimer_try_to_cancel(&w->timer))) {
+		w->counter = NO_SYNC;
+		return;
+	}
+
+	if (w->counter < NO_SYNC) {
+		if (w->ack) {
+			pulse_time -= BIN1_PULSE;
+			w->buf[w->counter] = 8;
+		} else {
+			pulse_time -= BIN0_PULSE;
+			w->buf[w->counter] = 0;
+		}
+		if (w->counter == 24) {	/* full frame */
+			walkera0701_parse_frame(w);
+			w->counter = NO_SYNC;
+			if (abs(pulse_time - SYNC_PULSE) < RESERVE)	/* new frame sync */
+				w->counter = 0;
+		} else {
+			if ((pulse_time > (ANALOG_MIN_PULSE - RESERVE)
+			     && (pulse_time < (ANALOG_MAX_PULSE + RESERVE)))) {
+				pulse_time -= (ANALOG_MIN_PULSE - RESERVE);
+				pulse_time = (u32) pulse_time / ANALOG_DELTA;	/* overtiping is safe, pulsetime < s32.. */
+				w->buf[w->counter++] |= (pulse_time & 7);
+			} else
+				w->counter = NO_SYNC;
+		}
+	} else if (abs(pulse_time - SYNC_PULSE - BIN0_PULSE) <
+				RESERVE + BIN1_PULSE - BIN0_PULSE)	/* frame sync .. */
+		w->counter = 0;
+
+	hrtimer_start(&w->timer, ktime_set(0, BIN_SAMPLE), HRTIMER_MODE_REL);
+}
+
+static enum hrtimer_restart timer_handler(struct hrtimer
+					  *handle)
+{
+	struct walkera_dev *w;
+
+	w = container_of(handle, struct walkera_dev, timer);
+	w->ack = read_ack(w->pardevice);
+
+	return HRTIMER_NORESTART;
+}
+
+static int walkera0701_open(struct input_dev *dev)
+{
+	struct walkera_dev *w = input_get_drvdata(dev);
+
+	parport_enable_irq(w->parport);
+	return 0;
+}
+
+static void walkera0701_close(struct input_dev *dev)
+{
+	struct walkera_dev *w = input_get_drvdata(dev);
+
+	parport_disable_irq(w->parport);
+}
+
+static int walkera0701_connect(struct walkera_dev *w, int parport)
+{
+	int err = -ENODEV;
+
+	w->parport = parport_find_number(parport);
+	if (w->parport == NULL)
+		return -ENODEV;
+
+	if (w->parport->irq == -1) {
+		printk(KERN_ERR "walkera0701: parport without interrupt\n");
+		goto init_err;
+	}
+
+	err = -EBUSY;
+	w->pardevice = parport_register_device(w->parport, "walkera0701",
+				    NULL, NULL, walkera0701_irq_handler,
+				    PARPORT_DEV_EXCL, w);
+	if (!w->pardevice)
+		goto init_err;
+
+	if (parport_negotiate(w->pardevice->port, IEEE1284_MODE_COMPAT))
+		goto init_err1;
+
+	if (parport_claim(w->pardevice))
+		goto init_err1;
+
+	w->input_dev = input_allocate_device();
+	if (!w->input_dev)
+		goto init_err2;
+
+	input_set_drvdata(w->input_dev, w);
+	w->input_dev->name = "Walkera WK-0701 TX";
+	w->input_dev->phys = w->parport->name;
+	w->input_dev->id.bustype = BUS_PARPORT;
+
+	/* TODO what id vendor/product/version ? */
+	w->input_dev->id.vendor = 0x0001;
+	w->input_dev->id.product = 0x0001;
+	w->input_dev->id.version = 0x0100;
+	w->input_dev->open = walkera0701_open;
+	w->input_dev->close = walkera0701_close;
+
+	w->input_dev->evbit[0] = BIT(EV_ABS) | BIT_MASK(EV_KEY);
+	w->input_dev->keybit[BIT_WORD(BTN_GEAR_DOWN)] = BIT_MASK(BTN_GEAR_DOWN);
+
+	input_set_abs_params(w->input_dev, ABS_X, -512, 512, 0, 0);
+	input_set_abs_params(w->input_dev, ABS_Y, -512, 512, 0, 0);
+	input_set_abs_params(w->input_dev, ABS_Z, -512, 512, 0, 0);
+	input_set_abs_params(w->input_dev, ABS_THROTTLE, -512, 512, 0, 0);
+	input_set_abs_params(w->input_dev, ABS_RUDDER, -512, 512, 0, 0);
+	input_set_abs_params(w->input_dev, ABS_MISC, -512, 512, 0, 0);
+
+	err = input_register_device(w->input_dev);
+	if (err)
+		goto init_err3;
+
+	hrtimer_init(&w->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	w->timer.function = timer_handler;
+	return 0;
+
+ init_err3:
+	input_free_device(w->input_dev);
+ init_err2:
+	parport_release(w->pardevice);
+ init_err1:
+	parport_unregister_device(w->pardevice);
+ init_err:
+	parport_put_port(w->parport);
+	return err;
+}
+
+static void walkera0701_disconnect(struct walkera_dev *w)
+{
+	hrtimer_cancel(&w->timer);
+	input_unregister_device(w->input_dev);
+	parport_release(w->pardevice);
+	parport_unregister_device(w->pardevice);
+	parport_put_port(w->parport);
+}
+
+static int __init walkera0701_init(void)
+{
+	return walkera0701_connect(&w_dev, walkera0701_pp_no);
+}
+
+static void __exit walkera0701_exit(void)
+{
+	walkera0701_disconnect(&w_dev);
+}
+
+module_init(walkera0701_init);
+module_exit(walkera0701_exit);
	1	+
	2	+Walkera WK-0701 transmitter is supplied with a ready to fly Walkera
	3	+helicopters such as HM36, HM37, HM60. The walkera0701 module enables to use
	4	+this transmitter as joystick
	5	+
	6	+Devel homepage and download:
	7	+http://zub.fei.tuke.sk/walkera-wk0701/
	8	+
	9	+or use cogito:
	10	+cg-clone http://zub.fei.tuke.sk/GIT/walkera0701-joystick
	11	+
	12	+
	13	+Connecting to PC:
	14	+
	15	+At back side of transmitter S-video connector can be found. Modulation
	16	+pulses from processor to HF part can be found at pin 2 of this connector,
	17	+pin 3 is GND. Between pin 3 and CPU 5k6 resistor can be found. To get
	18	+modulation pulses to PC, signal pulses must be amplified.
	19	+
	20	+Cable: (walkera TX to parport)
	21	+
	22	+Walkera WK-0701 TX S-VIDEO connector:
	23	+ (back side of TX)
	24	+ __ __ S-video: canon25
	25	+ / \|_\| \ pin 2 (signal) NPN parport
	26	+ / O 4 3 O \ pin 3 (GND) LED ________________ 10 ACK
	27	+ ( O 2 1 O ) \| C
	28	+ \ ___ / 2 ________________________\|\\|_____\|/
	29	+ \| [___] \| \|/\| B \|\
	30	+ ------- 3 __________________________________\|________________ 25 GND
	31	+ E
	32	+
	33	+
	34	+I use green LED and BC109 NPN transistor.
	35	+
	36	+Software:
	37	+
	38	+Build kernel with walkera0701 module. Module walkera0701 need exclusive
	39	+access to parport, modules like lp must be unloaded before loading
	40	+walkera0701 module, check dmesg for error messages. Connect TX to PC by
	41	+cable and run jstest /dev/input/js0 to see values from TX. If no value can
	42	+be changed by TX "joystick", check output from /proc/interrupts. Value for
	43	+(usually irq7) parport must increase if TX is on.
	44	+
	45	+
	46	+
	47	+Technical details:
	48	+
	49	+Driver use interrupt from parport ACK input bit to measure pulse length
	50	+using hrtimers.
	51	+
	52	+Frame format:
	53	+Based on walkera WK-0701 PCM Format description by Shaul Eizikovich.
	54	+(downloaded from http://www.smartpropoplus.com/Docs/Walkera_Wk-0701_PCM.pdf)
	55	+
	56	+Signal pulses:
	57	+ (ANALOG)
	58	+ SYNC BIN OCT
	59	+ +---------+ +------+
	60	+ \| \| \| \|
	61	+--+ +------+ +---
	62	+
	63	+Frame:
	64	+ SYNC , BIN1, OCT1, BIN2, OCT2 ... BIN24, OCT24, BIN25, next frame SYNC ..
	65	+
	66	+pulse length:
	67	+ Binary values: Analog octal values:
	68	+
	69	+ 288 uS Binary 0 318 uS 000
	70	+ 438 uS Binary 1 398 uS 001
	71	+ 478 uS 010
	72	+ 558 uS 011
	73	+ 638 uS 100
	74	+ 1306 uS SYNC 718 uS 101
	75	+ 798 uS 110
	76	+ 878 uS 111
	77	+
	78	+24 bin+oct values + 1 bin value = 24*4+1 bits = 97 bits
	79	+
	80	+(Warning, pulses on ACK ar inverted by transistor, irq is rised up on sync
	81	+to bin change or octal value to bin change).
	82	+
	83	+Binary data representations:
	84	+
	85	+One binary and octal value can be grouped to nibble. 24 nibbles + one binary
	86	+values can be sampled between sync pulses.
	87	+
	88	+Values for first four channels (analog joystick values) can be found in
	89	+first 10 nibbles. Analog value is represented by one sign bit and 9 bit
	90	+absolute binary value. (10 bits per channel). Next nibble is checksum for
	91	+first ten nibbles.
	92	+
	93	+Next nibbles 12 .. 21 represents four channels (not all channels can be
	94	+directly controlled from TX). Binary representations ar the same as in first
	95	+four channels. In nibbles 22 and 23 is a special magic number. Nibble 24 is
	96	+checksum for nibbles 12..23.
	97	+
	98	+After last octal value for nibble 24 and next sync pulse one additional
	99	+binary value can be sampled. This bit and magic number is not used in
	100	+software driver. Some details about this magic numbers can be found in
	101	+Walkera_Wk-0701_PCM.pdf.
	102	+
	103	+Checksum calculation:
	104	+
	105	+Summary of octal values in nibbles must be same as octal value in checksum
	106	+nibble (only first 3 bits are used). Binary value for checksum nibble is
	107	+calculated by sum of binary values in checked nibbles + sum of octal values
	108	+in checked nibbles divided by 8. Only bit 0 of this sum is used.
...	...	@@ -294,5 +294,17 @@
294	294	This option enables support for the LED which surrounds the Big X on
295	295	XBox 360 controller.
296	296
	297	+config JOYSTICK_WALKERA0701
	298	+ tristate "Walkera WK-0701 RC transmitter"
	299	+ depends on HIGH_RES_TIMERS && PARPORT
	300	+ help
	301	+ Say Y or M here if you have a Walkera WK-0701 transmitter which is
	302	+ supplied with a ready to fly Walkera helicopters such as HM36,
	303	+ HM37, HM60 and want to use it via parport as a joystick. More
	304	+ information is available: <file:Documentation/input/walkera0701.txt>
	305	+
	306	+ To compile this driver as a module, choose M here: the
	307	+ module will be called walkera0701.
	308	+
297	309	endif
...	...	@@ -29,4 +29,5 @@
29	29	obj-$(CONFIG_JOYSTICK_WARRIOR) += warrior.o
30	30	obj-$(CONFIG_JOYSTICK_XPAD) += xpad.o
31	31	obj-$(CONFIG_JOYSTICK_ZHENHUA) += zhenhua.o
	32	+obj-$(CONFIG_JOYSTICK_WALKERA0701) += walkera0701.o
	1	+/*
	2	+ * Parallel port to Walkera WK-0701 TX joystick
	3	+ *
	4	+ * Copyright (c) 2008 Peter Popovec
	5	+ *
	6	+ * More about driver: <file:Documentation/input/walkera0701.txt>
	7	+ */
	8	+
	9	+/*
	10	+ * This program is free software; you can redistribute it and/or modify it
	11	+ * under the terms of the GNU General Public License version 2 as published by
	12	+ * the Free Software Foundation.
	13	+*/
	14	+
	15	+/* #define WK0701_DEBUG */
	16	+
	17	+#define RESERVE 20000
	18	+#define SYNC_PULSE 1306000
	19	+#define BIN0_PULSE 288000
	20	+#define BIN1_PULSE 438000
	21	+
	22	+#define ANALOG_MIN_PULSE 318000
	23	+#define ANALOG_MAX_PULSE 878000
	24	+#define ANALOG_DELTA 80000
	25	+
	26	+#define BIN_SAMPLE ((BIN0_PULSE + BIN1_PULSE) / 2)
	27	+
	28	+#define NO_SYNC 25
	29	+
	30	+#include <linux/kernel.h>
	31	+#include <linux/module.h>
	32	+#include <linux/parport.h>
	33	+#include <linux/input.h>
	34	+#include <linux/hrtimer.h>
	35	+
	36	+MODULE_AUTHOR("Peter Popovec <popovec@fei.tuke.sk>");
	37	+MODULE_DESCRIPTION("Walkera WK-0701 TX as joystick");
	38	+MODULE_LICENSE("GPL");
	39	+
	40	+static unsigned int walkera0701_pp_no;
	41	+module_param_named(port, walkera0701_pp_no, int, 0);
	42	+MODULE_PARM_DESC(port,
	43	+ "Parallel port adapter for Walkera WK-0701 TX (default is 0)");
	44	+
	45	+/*
	46	+ * For now, only one device is supported, if somebody need more devices, code
	47	+ * can be expanded, one struct walkera_dev per device must be allocated and
	48	+ * set up by walkera0701_connect (release of device by walkera0701_disconnect)
	49	+ */
	50	+
	51	+struct walkera_dev {
	52	+ unsigned char buf[25];
	53	+ u64 irq_time, irq_lasttime;
	54	+ int counter;
	55	+ int ack;
	56	+
	57	+ struct input_dev *input_dev;
	58	+ struct hrtimer timer;
	59	+
	60	+ struct parport *parport;
	61	+ struct pardevice *pardevice;
	62	+};
	63	+
	64	+static struct walkera_dev w_dev;
	65	+
	66	+static inline void walkera0701_parse_frame(struct walkera_dev *w)
	67	+{
	68	+ int i;
	69	+ int val1, val2, val3, val4, val5, val6, val7, val8;
	70	+ int crc1, crc2;
	71	+
	72	+ for (crc1 = crc2 = i = 0; i < 10; i++) {
	73	+ crc1 += w->buf[i] & 7;
	74	+ crc2 += (w->buf[i] & 8) >> 3;
	75	+ }
	76	+ if ((w->buf[10] & 7) != (crc1 & 7))
	77	+ return;
	78	+ if (((w->buf[10] & 8) >> 3) != (((crc1 >> 3) + crc2) & 1))
	79	+ return;
	80	+ for (crc1 = crc2 = 0, i = 11; i < 23; i++) {
	81	+ crc1 += w->buf[i] & 7;
	82	+ crc2 += (w->buf[i] & 8) >> 3;
	83	+ }
	84	+ if ((w->buf[23] & 7) != (crc1 & 7))
	85	+ return;
	86	+ if (((w->buf[23] & 8) >> 3) != (((crc1 >> 3) + crc2) & 1))
	87	+ return;
	88	+ val1 = ((w->buf[0] & 7) * 256 + w->buf[1] * 16 + w->buf[2]) >> 2;
	89	+ val1 = ((w->buf[0] >> 2) & 2) - 1; / sign */
	90	+ val2 = (w->buf[2] & 1) << 8 \| (w->buf[3] << 4) \| w->buf[4];
	91	+ val2 = (w->buf[2] & 2) - 1; / sign */
	92	+ val3 = ((w->buf[5] & 7) * 256 + w->buf[6] * 16 + w->buf[7]) >> 2;
	93	+ val3 = ((w->buf[5] >> 2) & 2) - 1; / sign */
	94	+ val4 = (w->buf[7] & 1) << 8 \| (w->buf[8] << 4) \| w->buf[9];
	95	+ val4 = (w->buf[7] & 2) - 1; / sign */
	96	+ val5 = ((w->buf[11] & 7) * 256 + w->buf[12] * 16 + w->buf[13]) >> 2;
	97	+ val5 = ((w->buf[11] >> 2) & 2) - 1; / sign */
	98	+ val6 = (w->buf[13] & 1) << 8 \| (w->buf[14] << 4) \| w->buf[15];
	99	+ val6 = (w->buf[13] & 2) - 1; / sign */
	100	+ val7 = ((w->buf[16] & 7) * 256 + w->buf[17] * 16 + w->buf[18]) >> 2;
	101	+ val7 = ((w->buf[16] >> 2) & 2) - 1; /sign */
	102	+ val8 = (w->buf[18] & 1) << 8 \| (w->buf[19] << 4) \| w->buf[20];
	103	+ val8 = (w->buf[18] & 2) - 1; /sign */
	104	+
	105	+#ifdef WK0701_DEBUG
	106	+ {
	107	+ int magic, magic_bit;
	108	+ magic = (w->buf[21] << 4) \| w->buf[22];
	109	+ magic_bit = (w->buf[24] & 8) >> 3;
	110	+ printk(KERN_DEBUG
	111	+ "walkera0701: %4d %4d %4d %4d %4d %4d %4d %4d (magic %2x %d)\n",
	112	+ val1, val2, val3, val4, val5, val6, val7, val8, magic,
	113	+ magic_bit);
	114	+ }
	115	+#endif
	116	+ input_report_abs(w->input_dev, ABS_X, val2);
	117	+ input_report_abs(w->input_dev, ABS_Y, val1);
	118	+ input_report_abs(w->input_dev, ABS_Z, val6);
	119	+ input_report_abs(w->input_dev, ABS_THROTTLE, val3);
	120	+ input_report_abs(w->input_dev, ABS_RUDDER, val4);
	121	+ input_report_abs(w->input_dev, ABS_MISC, val7);
	122	+ input_report_key(w->input_dev, BTN_GEAR_DOWN, val5 > 0);
	123	+}
	124	+
	125	+static inline int read_ack(struct pardevice *p)
	126	+{
	127	+ return parport_read_status(p->port) & 0x40;
	128	+}
	129	+
	130	+/* falling edge, prepare to BIN value calculation */
	131	+static void walkera0701_irq_handler(void *handler_data)
	132	+{
	133	+ u64 pulse_time;
	134	+ struct walkera_dev *w = handler_data;
	135	+
	136	+ w->irq_time = ktime_to_ns(ktime_get());
	137	+ pulse_time = w->irq_time - w->irq_lasttime;
	138	+ w->irq_lasttime = w->irq_time;
	139	+
	140	+ /* cancel timer, if in handler or active do resync */
	141	+ if (unlikely(0 != hrtimer_try_to_cancel(&w->timer))) {
	142	+ w->counter = NO_SYNC;
	143	+ return;
	144	+ }
	145	+
	146	+ if (w->counter < NO_SYNC) {
	147	+ if (w->ack) {
	148	+ pulse_time -= BIN1_PULSE;
	149	+ w->buf[w->counter] = 8;
	150	+ } else {
	151	+ pulse_time -= BIN0_PULSE;
	152	+ w->buf[w->counter] = 0;
	153	+ }
	154	+ if (w->counter == 24) { /* full frame */
	155	+ walkera0701_parse_frame(w);
	156	+ w->counter = NO_SYNC;
	157	+ if (abs(pulse_time - SYNC_PULSE) < RESERVE) /* new frame sync */
	158	+ w->counter = 0;
	159	+ } else {
	160	+ if ((pulse_time > (ANALOG_MIN_PULSE - RESERVE)
	161	+ && (pulse_time < (ANALOG_MAX_PULSE + RESERVE)))) {
	162	+ pulse_time -= (ANALOG_MIN_PULSE - RESERVE);
	163	+ pulse_time = (u32) pulse_time / ANALOG_DELTA; /* overtiping is safe, pulsetime < s32.. */
	164	+ w->buf[w->counter++] \|= (pulse_time & 7);
	165	+ } else
	166	+ w->counter = NO_SYNC;
	167	+ }
	168	+ } else if (abs(pulse_time - SYNC_PULSE - BIN0_PULSE) <
	169	+ RESERVE + BIN1_PULSE - BIN0_PULSE) /* frame sync .. */
	170	+ w->counter = 0;
	171	+
	172	+ hrtimer_start(&w->timer, ktime_set(0, BIN_SAMPLE), HRTIMER_MODE_REL);
	173	+}
	174	+
	175	+static enum hrtimer_restart timer_handler(struct hrtimer
	176	+ *handle)
	177	+{
	178	+ struct walkera_dev *w;
	179	+
	180	+ w = container_of(handle, struct walkera_dev, timer);
	181	+ w->ack = read_ack(w->pardevice);
	182	+
	183	+ return HRTIMER_NORESTART;
	184	+}
	185	+
	186	+static int walkera0701_open(struct input_dev *dev)
	187	+{
	188	+ struct walkera_dev *w = input_get_drvdata(dev);
	189	+
	190	+ parport_enable_irq(w->parport);
	191	+ return 0;
	192	+}
	193	+
	194	+static void walkera0701_close(struct input_dev *dev)
	195	+{
	196	+ struct walkera_dev *w = input_get_drvdata(dev);
	197	+
	198	+ parport_disable_irq(w->parport);
	199	+}
	200	+
	201	+static int walkera0701_connect(struct walkera_dev *w, int parport)
	202	+{
	203	+ int err = -ENODEV;
	204	+
	205	+ w->parport = parport_find_number(parport);
	206	+ if (w->parport == NULL)
	207	+ return -ENODEV;
	208	+
	209	+ if (w->parport->irq == -1) {
	210	+ printk(KERN_ERR "walkera0701: parport without interrupt\n");
	211	+ goto init_err;
	212	+ }
	213	+
	214	+ err = -EBUSY;
	215	+ w->pardevice = parport_register_device(w->parport, "walkera0701",
	216	+ NULL, NULL, walkera0701_irq_handler,
	217	+ PARPORT_DEV_EXCL, w);
	218	+ if (!w->pardevice)
	219	+ goto init_err;
	220	+
	221	+ if (parport_negotiate(w->pardevice->port, IEEE1284_MODE_COMPAT))
	222	+ goto init_err1;
	223	+
	224	+ if (parport_claim(w->pardevice))
	225	+ goto init_err1;
	226	+
	227	+ w->input_dev = input_allocate_device();
	228	+ if (!w->input_dev)
	229	+ goto init_err2;
	230	+
	231	+ input_set_drvdata(w->input_dev, w);
	232	+ w->input_dev->name = "Walkera WK-0701 TX";
	233	+ w->input_dev->phys = w->parport->name;
	234	+ w->input_dev->id.bustype = BUS_PARPORT;
	235	+
	236	+ /* TODO what id vendor/product/version ? */
	237	+ w->input_dev->id.vendor = 0x0001;
	238	+ w->input_dev->id.product = 0x0001;
	239	+ w->input_dev->id.version = 0x0100;
	240	+ w->input_dev->open = walkera0701_open;
	241	+ w->input_dev->close = walkera0701_close;
	242	+
	243	+ w->input_dev->evbit[0] = BIT(EV_ABS) \| BIT_MASK(EV_KEY);
	244	+ w->input_dev->keybit[BIT_WORD(BTN_GEAR_DOWN)] = BIT_MASK(BTN_GEAR_DOWN);
	245	+
	246	+ input_set_abs_params(w->input_dev, ABS_X, -512, 512, 0, 0);
	247	+ input_set_abs_params(w->input_dev, ABS_Y, -512, 512, 0, 0);
	248	+ input_set_abs_params(w->input_dev, ABS_Z, -512, 512, 0, 0);
	249	+ input_set_abs_params(w->input_dev, ABS_THROTTLE, -512, 512, 0, 0);
	250	+ input_set_abs_params(w->input_dev, ABS_RUDDER, -512, 512, 0, 0);
	251	+ input_set_abs_params(w->input_dev, ABS_MISC, -512, 512, 0, 0);
	252	+
	253	+ err = input_register_device(w->input_dev);
	254	+ if (err)
	255	+ goto init_err3;
	256	+
	257	+ hrtimer_init(&w->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	258	+ w->timer.function = timer_handler;
	259	+ return 0;
	260	+
	261	+ init_err3:
	262	+ input_free_device(w->input_dev);
	263	+ init_err2:
	264	+ parport_release(w->pardevice);
	265	+ init_err1:
	266	+ parport_unregister_device(w->pardevice);
	267	+ init_err:
	268	+ parport_put_port(w->parport);
	269	+ return err;
	270	+}
	271	+
	272	+static void walkera0701_disconnect(struct walkera_dev *w)
	273	+{
	274	+ hrtimer_cancel(&w->timer);
	275	+ input_unregister_device(w->input_dev);
	276	+ parport_release(w->pardevice);
	277	+ parport_unregister_device(w->pardevice);
	278	+ parport_put_port(w->parport);
	279	+}
	280	+
	281	+static int __init walkera0701_init(void)
	282	+{
	283	+ return walkera0701_connect(&w_dev, walkera0701_pp_no);
	284	+}
	285	+
	286	+static void __exit walkera0701_exit(void)
	287	+{
	288	+ walkera0701_disconnect(&w_dev);
	289	+}
	290	+
	291	+module_init(walkera0701_init);
	292	+module_exit(walkera0701_exit);