On Fri, 2010-04-09 at 01:04 +0200, David Härdeman wrote:
> This patch adds an RC6 decoder (modes 0 and 6A) to ir-core.
>
> Signed-off-by: David Härdeman <david@xxxxxxxxxxx>
David,
Overall, a nice job of implementing RC6 decoder logic. I have a few
comments below (along with some of me reasoning to myself out loud).
> ---
> drivers/media/IR/Kconfig | 9 +
> drivers/media/IR/Makefile | 1
> drivers/media/IR/ir-core-priv.h | 7 +
> drivers/media/IR/ir-raw-event.c | 1
> drivers/media/IR/ir-rc6-decoder.c | 412 +++++++++++++++++++++++++++++++++++++
> drivers/media/IR/ir-sysfs.c | 2
> include/media/rc-map.h | 1
> 7 files changed, 433 insertions(+), 0 deletions(-)
> create mode 100644 drivers/media/IR/ir-rc6-decoder.c
>
> diff --git a/drivers/media/IR/Kconfig b/drivers/media/IR/Kconfig
> index ba81bda..28d336d 100644
> --- a/drivers/media/IR/Kconfig
> +++ b/drivers/media/IR/Kconfig
> @@ -27,3 +27,12 @@ config IR_RC5_DECODER
> ---help---
> Enable this option if you have IR with RC-5 protocol, and
> if the IR is decoded in software
> +
> +config IR_RC6_DECODER
> + tristate "Enable IR raw decoder for the RC6 protocol"
> + depends on IR_CORE
> + default y
> +
> + ---help---
> + Enable this option if you have an infrared remote control which
> + uses the RC6 protocol, and you need software decoding support.
> diff --git a/drivers/media/IR/Makefile b/drivers/media/IR/Makefile
> index 62e12d5..792d9ca 100644
> --- a/drivers/media/IR/Makefile
> +++ b/drivers/media/IR/Makefile
> @@ -7,3 +7,4 @@ obj-$(CONFIG_IR_CORE) += ir-core.o
> obj-$(CONFIG_VIDEO_IR) += ir-common.o
> obj-$(CONFIG_IR_NEC_DECODER) += ir-nec-decoder.o
> obj-$(CONFIG_IR_RC5_DECODER) += ir-rc5-decoder.o
> +obj-$(CONFIG_IR_RC6_DECODER) += ir-rc6-decoder.o
> diff --git a/drivers/media/IR/ir-core-priv.h b/drivers/media/IR/ir-core-priv.h
> index ab785bc..853ec80 100644
> --- a/drivers/media/IR/ir-core-priv.h
> +++ b/drivers/media/IR/ir-core-priv.h
> @@ -109,4 +109,11 @@ void ir_raw_init(void);
> #define load_rc5_decode() 0
> #endif
>
> +/* from ir-rc6-decoder.c */
> +#ifdef CONFIG_IR_RC5_DECODER_MODULE
> +#define load_rc6_decode() request_module("ir-rc6-decoder")
> +#else
> +#define load_rc6_decode() 0
> +#endif
> +
> #endif /* _IR_RAW_EVENT */
> diff --git a/drivers/media/IR/ir-raw-event.c b/drivers/media/IR/ir-raw-event.c
> index 2efc051..ef0f231 100644
> --- a/drivers/media/IR/ir-raw-event.c
> +++ b/drivers/media/IR/ir-raw-event.c
> @@ -224,6 +224,7 @@ static void init_decoders(struct work_struct *work)
>
> load_nec_decode();
> load_rc5_decode();
> + load_rc6_decode();
>
> /* If needed, we may later add some init code. In this case,
> it is needed to change the CONFIG_MODULE test at ir-core.h
> diff --git a/drivers/media/IR/ir-rc6-decoder.c b/drivers/media/IR/ir-rc6-decoder.c
> new file mode 100644
> index 0000000..ccc5be2
> --- /dev/null
> +++ b/drivers/media/IR/ir-rc6-decoder.c
> @@ -0,0 +1,412 @@
> +/* ir-rc6-decoder.c - A decoder for the RC6 IR protocol
> + *
> + * Copyright (C) 2010 by David Härdeman <david@xxxxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation version 2 of the License.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include "ir-core-priv.h"
> +
> +/*
> + * This decoder currently supports:
> + * RC6-0-16 (standard toggle bit in header)
> + * RC6-6A-24 (no toggle bit)
> + * RC6-6A-32 (MCE version with toggle bit in body)
> + */
Just for reference for review:
http://slycontrol.ru/scr/kb/rc6.htm
http://www.picbasic.nl/info_rc6_uk.htm
RC6 Mode 0:
prefix mark: 111111
prefix space: 00
start bit: 10 (biphase encoding of '1')
mode bits: 010101 (biphase encoding of '000')
toggle bits: 0011 or 1100 (double duration biphase coding of '0' or '1')
system byte: xxxxxxxxxxxxxxxx (biphase encoding of 8 bits)
command byte: yyyyyyyyyyyyyyyy (biphase encoding of 8 bits)
RC6 Mode 6A:
prefix mark: 111111
prefix space: 00
start bit: 10 (biphase encoding of '1')
mode bits: 101001 (biphase encoding of '110' for '6')
trailer bits: 0011 (double duration biphase encoding of '0' for 'A')
customer len: 01 or 10 (biphase encoding of '0' for 7 bits or '1' for 15 bits)
customer bits: xxxxxxxxxxxxxx (biphase encoding of 7 bits for a short customer code)
or
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx (biphase encoding of 15 bits for a long customer code)
system byte: yyyyyyyyyyyyyyyy (biphase encoding of 8 bits)
command byte: zzzzzzzzzzzzzzzz (biphase encoding of 8 bits)
> +#define RC6_UNIT 444444 /* us */
> +#define RC6_HEADER_NBITS 4 /* not including toggle bit */
> +#define RC6_0_NBITS 16
> +#define RC6_6A_SMALL_NBITS 24
> +#define RC6_6A_LARGE_NBITS 32
According to the slycontrol.ru website, the data length is, in theory
OEM dependent for Mode 6A, limited to a max of 24 bits (3 bytes) after a
short customer code and 128 bits (16 bytes) after a long customer code.
I don't know what the reality is for existing remotes.
Would it be better to look for the signal free time of 6 RC6_UNITs to
declare the end of reception, instead of a bit count?
> +#define RC6_PREFIX_PULSE PULSE(6)
> +#define RC6_PREFIX_SPACE SPACE(2)
> +#define RC6_MODE_MASK 0x07 /* for the header bits */
> +#define RC6_STARTBIT_MASK 0x08 /* for the header bits */
> +#define RC6_6A_MCE_TOGGLE_MASK 0x8000 /* for the body bits */
That's an OEM specific toggle bit. It is likely more properly named
RC6_6A_MS_TOGGLE_MASK. See slide 6 of:
http://download.microsoft.com/download/9/8/f/98f3fe47-dfc3-4e74-92a3-088782200fe7/TWEN05007_WinHEC05.ppt
(Although in reality, every remote that wants to work with stock MS
drivers will use it.)
> +
> +/* Used to register rc6_decoder clients */
> +static LIST_HEAD(decoder_list);
> +static DEFINE_SPINLOCK(decoder_lock);
> +
> +enum rc6_mode {
> + RC6_MODE_0,
> + RC6_MODE_6A,
> + RC6_MODE_UNKNOWN,
> +};
> +
> +enum rc6_state {
> + STATE_INACTIVE,
> + STATE_PREFIX_SPACE,
> + STATE_HEADER_BIT_START,
> + STATE_HEADER_BIT_END,
> + STATE_TOGGLE_START,
> + STATE_TOGGLE_END,
> + STATE_BODY_BIT_START,
> + STATE_BODY_BIT_END,
> + STATE_FINISHED,
> +};
> +
> +struct decoder_data {
> + struct list_head list;
> + struct ir_input_dev *ir_dev;
> + int enabled:1;
> +
> + /* State machine control */
> + enum rc6_state state;
> + u8 header;
> + u32 body;
> + int last_unit;
> + bool toggle;
> + unsigned count;
> + unsigned wanted_bits;
> +};
> +
> +
> +/**
> + * get_decoder_data() - gets decoder data
> + * @input_dev: input device
> + *
> + * Returns the struct decoder_data that corresponds to a device
> + */
> +static struct decoder_data *get_decoder_data(struct ir_input_dev *ir_dev)
> +{
> + struct decoder_data *data = NULL;
> +
> + spin_lock(&decoder_lock);
> + list_for_each_entry(data, &decoder_list, list) {
> + if (data->ir_dev == ir_dev)
> + break;
> + }
> + spin_unlock(&decoder_lock);
> + return data;
> +}
> +
> +static ssize_t store_enabled(struct device *d,
> + struct device_attribute *mattr,
> + const char *buf,
> + size_t len)
> +{
> + unsigned long value;
> + struct ir_input_dev *ir_dev = dev_get_drvdata(d);
> + struct decoder_data *data = get_decoder_data(ir_dev);
> +
> + if (!data)
> + return -EINVAL;
> +
> + if (strict_strtoul(buf, 10, &value) || value > 1)
> + return -EINVAL;
> +
> + data->enabled = value;
> +
> + return len;
> +}
> +
> +static ssize_t show_enabled(struct device *d,
> + struct device_attribute *mattr, char *buf)
> +{
> + struct ir_input_dev *ir_dev = dev_get_drvdata(d);
> + struct decoder_data *data = get_decoder_data(ir_dev);
> +
> + if (!data)
> + return -EINVAL;
> +
> + if (data->enabled)
> + return sprintf(buf, "1\n");
> + else
> + return sprintf(buf, "0\n");
> +}
> +
> +static DEVICE_ATTR(enabled, S_IRUGO | S_IWUSR, show_enabled, store_enabled);
> +
> +static struct attribute *decoder_attributes[] = {
> + &dev_attr_enabled.attr,
> + NULL
> +};
> +
> +static struct attribute_group decoder_attribute_group = {
> + .name = "rc6_decoder",
> + .attrs = decoder_attributes,
> +};
> +
> +static enum rc6_mode rc6_mode(struct decoder_data *data) {
> + switch (data->header & RC6_MODE_MASK) {
> + case 0:
> + return RC6_MODE_0;
> + case 6:
> + if (!data->toggle)
> + return RC6_MODE_6A;
> + /* fall through */
> + default:
> + return RC6_MODE_UNKNOWN;
> + }
> +}
> +
> +/**
> + * ir_rc6_decode() - Decode one RC6 pulse or space
> + * @input_dev: the struct input_dev descriptor of the device
> + * @duration: duration of pulse/space in ns
> + *
> + * This function returns -EINVAL if the pulse violates the state machine
> + */
> +static int ir_rc6_decode(struct input_dev *input_dev, s64 duration)
> +{
> + struct decoder_data *data;
> + struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
> + u32 scancode;
> + u8 toggle;
> + int u;
> +
> + data = get_decoder_data(ir_dev);
> + if (!data)
> + return -EINVAL;
> +
> + if (!data->enabled)
> + return 0;
> +
> + if (IS_RESET(duration)) {
> + data->state = STATE_INACTIVE;
> + return 0;
> + }
> +
> + u = TO_UNITS(duration, RC6_UNIT);
> + if (DURATION(u) == 0)
> + goto out;
> +
> +again:
> + IR_dprintk(2, "RC6 decode started at state %i (%i units, %ius)\n",
> + data->state, u, TO_US(duration));
> +
> + if (DURATION(u) == 0 && data->state != STATE_FINISHED)
> + return 0;
Isn't there a better way to structure the logic to break up two adjacent
pulse units than with goto's out of the switch back up to here?
A do {} while() loop would have been much clearer.
> + switch (data->state) {
> +
> + case STATE_INACTIVE:
> + if (u >= RC6_PREFIX_PULSE - 1 && u <= RC6_PREFIX_PULSE + 1) {
> + data->state = STATE_PREFIX_SPACE;
> + data->count = 0;
> + return 0;
> + }
> + break;
> +
> + case STATE_PREFIX_SPACE:
> + if (u == RC6_PREFIX_SPACE) {
> + data->state = STATE_HEADER_BIT_START;
> + return 0;
> + }
> + break;
> +
> + case STATE_HEADER_BIT_START:
> + if (DURATION(u) == 1) {
> + data->header <<= 1;
> + if (IS_PULSE(u))
> + data->header |= 1;
> + data->count++;
> + data->last_unit = u;
> + data->state = STATE_HEADER_BIT_END;
> + return 0;
> + }
> + break;
> +
> + case STATE_HEADER_BIT_END:
> + if (IS_TRANSITION(u, data->last_unit)) {
> + if (data->count == RC6_HEADER_NBITS)
> + data->state = STATE_TOGGLE_START;
> + else
> + data->state = STATE_HEADER_BIT_START;
> +
> + DECREASE_DURATION(u, 1);
> + goto again;
> + }
> + break;
> +
> + case STATE_TOGGLE_START:
> + if (DURATION(u) == 2) {
> + data->toggle = IS_PULSE(u);
> + data->last_unit = u;
> + data->state = STATE_TOGGLE_END;
> + return 0;
> + }
> + break;
> +
> + case STATE_TOGGLE_END:
> + if (IS_TRANSITION(u, data->last_unit) && DURATION(u) >= 2) {
> + data->state = STATE_BODY_BIT_START;
> + data->last_unit = u;
> + DECREASE_DURATION(u, 2);
> + data->count = 0;
> +
> + if (!(data->header & RC6_STARTBIT_MASK)) {
> + IR_dprintk(1, "RC6 invalid start bit\n");
> + break;
> + }
> +
> + switch (rc6_mode(data)) {
> + case RC6_MODE_0:
> + data->wanted_bits = RC6_0_NBITS;
> + break;
> + case RC6_MODE_6A:
> + /* This might look weird, but we basically
> + check the value of the first body bit to
> + determine the number of bits in mode 6A */
This bit basically only tells you the length of the customer code: 7 or
15 bits.
> + if ((DURATION(u) == 0 && IS_SPACE(data->last_unit)) || DURATION(u) > 0)
> + data->wanted_bits = RC6_6A_LARGE_NBITS;
> + else
> + data->wanted_bits = RC6_6A_SMALL_NBITS;
> + break;
> + default:
> + IR_dprintk(1, "RC6 unknown mode\n");
> + goto out;
> + }
> + goto again;
> + }
> + break;
> +
> + case STATE_BODY_BIT_START:
> + if (DURATION(u) == 1) {
> + data->body <<= 1;
> + if (IS_PULSE(u))
> + data->body |= 1;
> + data->count++;
> + data->last_unit = u;
> +
> + /*
> + * If the last bit is one, a space will merge
> + * with the silence after the command.
> + */
> + if (IS_PULSE(u) && data->count == data->wanted_bits) {
> + data->state = STATE_FINISHED;
> + goto again;
> + }
> +
> + data->state = STATE_BODY_BIT_END;
> + return 0;
> + }
> + break;
> +
> + case STATE_BODY_BIT_END:
> + if (IS_TRANSITION(u, data->last_unit)) {
> + if (data->count == data->wanted_bits)
> + data->state = STATE_FINISHED;
> + else
> + data->state = STATE_BODY_BIT_START;
> +
> + DECREASE_DURATION(u, 1);
> + goto again;
> + }
> + break;
> +
> + case STATE_FINISHED:
> + switch (rc6_mode(data)) {
> + case RC6_MODE_0:
> + scancode = data->body & 0xffff;
> + toggle = data->toggle;
> + IR_dprintk(1, "RC6(0) scancode 0x%04x (toggle: %u)\n",
> + scancode, toggle);
> + break;
> + case RC6_MODE_6A:
> + if (data->wanted_bits == RC6_6A_LARGE_NBITS) {
> + toggle = data->body & RC6_6A_MCE_TOGGLE_MASK ? 1 : 0;
> + scancode = data->body & ~RC6_6A_MCE_TOGGLE_MASK;
Technically this depends on the OEM. In reality, every RC6 Mode 6A
remote that wants to work with Microsoft stock drivers will likely use
this bit as a toggle.
Regards,
Andy
> + } else {
> + toggle = 0;
> + scancode = data->body & 0xffffff;
> + }
> +
> + IR_dprintk(1, "RC6(6A) scancode 0x%08x (toggle: %u)\n",
> + scancode, toggle);
> + break;
> + default:
> + IR_dprintk(1, "RC6 unknown mode\n");
> + goto out;
> + }
> +
> + ir_keydown(input_dev, scancode, toggle);
> + data->state = STATE_INACTIVE;
> + return 0;
> + }
> +
> +out:
> + IR_dprintk(1, "RC6 decode failed at state %i (%i units, %ius)\n",
> + data->state, u, TO_US(duration));
> + data->state = STATE_INACTIVE;
> + return -EINVAL;
> +}
> +
> +static int ir_rc6_register(struct input_dev *input_dev)
> +{
> + struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
> + struct decoder_data *data;
> + int rc;
> +
> + rc = sysfs_create_group(&ir_dev->dev.kobj, &decoder_attribute_group);
> + if (rc < 0)
> + return rc;
> +
> + data = kzalloc(sizeof(*data), GFP_KERNEL);
> + if (!data) {
> + sysfs_remove_group(&ir_dev->dev.kobj, &decoder_attribute_group);
> + return -ENOMEM;
> + }
> +
> + data->ir_dev = ir_dev;
> + data->enabled = 1;
> +
> + spin_lock(&decoder_lock);
> + list_add_tail(&data->list, &decoder_list);
> + spin_unlock(&decoder_lock);
> +
> + return 0;
> +}
> +
> +static int ir_rc6_unregister(struct input_dev *input_dev)
> +{
> + struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
> + static struct decoder_data *data;
> +
> + data = get_decoder_data(ir_dev);
> + if (!data)
> + return 0;
> +
> + sysfs_remove_group(&ir_dev->dev.kobj, &decoder_attribute_group);
> +
> + spin_lock(&decoder_lock);
> + list_del(&data->list);
> + spin_unlock(&decoder_lock);
> +
> + return 0;
> +}
> +
> +static struct ir_raw_handler rc6_handler = {
> + .decode = ir_rc6_decode,
> + .raw_register = ir_rc6_register,
> + .raw_unregister = ir_rc6_unregister,
> +};
> +
> +static int __init ir_rc6_decode_init(void)
> +{
> + ir_raw_handler_register(&rc6_handler);
> +
> + printk(KERN_INFO "IR RC6 protocol handler initialized\n");
> + return 0;
> +}
> +
> +static void __exit ir_rc6_decode_exit(void)
> +{
> + ir_raw_handler_unregister(&rc6_handler);
> +}
> +
> +module_init(ir_rc6_decode_init);
> +module_exit(ir_rc6_decode_exit);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("David Härdeman <david@xxxxxxxxxxx>");
> +MODULE_DESCRIPTION("RC6 IR protocol decoder");
> diff --git a/drivers/media/IR/ir-sysfs.c b/drivers/media/IR/ir-sysfs.c
> index a222d4f..d7ec973 100644
> --- a/drivers/media/IR/ir-sysfs.c
> +++ b/drivers/media/IR/ir-sysfs.c
> @@ -60,6 +60,8 @@ static ssize_t show_protocol(struct device *d,
> s = "pulse-distance";
> else if (ir_type == IR_TYPE_NEC)
> s = "nec";
> + else if (ir_type == IR_TYPE_RC6)
> + s = "rc6";
> else
> s = "other";
>
> diff --git a/include/media/rc-map.h b/include/media/rc-map.h
> index 3b7fe5a..11f6618 100644
> --- a/include/media/rc-map.h
> +++ b/include/media/rc-map.h
> @@ -15,6 +15,7 @@
> #define IR_TYPE_RC5 (1 << 0) /* Philips RC5 protocol */
> #define IR_TYPE_PD (1 << 1) /* Pulse distance encoded IR */
> #define IR_TYPE_NEC (1 << 2)
> +#define IR_TYPE_RC6 (1 << 3) /* Philips RC6 protocol */
> #define IR_TYPE_OTHER (1u << 31)
>
> struct ir_scancode {
>
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