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372 lines
8.6 KiB
C
372 lines
8.6 KiB
C
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/* ir-rc5-decoder.c - handle RC-5 IR Pulse/Space protocol
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*
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* Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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/*
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* This code only handles 14 bits RC-5 protocols. There are other variants
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* that use a different number of bits. This is currently unsupported
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*/
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#include <media/ir-core.h>
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#define RC5_NBITS 14
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#define RC5_HALFBIT 888888 /* ns */
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#define RC5_BIT (RC5_HALFBIT * 2)
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#define RC5_DURATION (RC5_BIT * RC5_NBITS)
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#define is_rc5_halfbit(nsec) ((ev->delta.tv_nsec >= RC5_HALFBIT / 2) && \
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(ev->delta.tv_nsec < RC5_HALFBIT + RC5_HALFBIT / 2))
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#define n_half(nsec) ((ev->delta.tv_nsec + RC5_HALFBIT / 2) / RC5_HALFBIT)
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/* Used to register rc5_decoder clients */
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static LIST_HEAD(decoder_list);
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static spinlock_t decoder_lock;
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enum rc5_state {
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STATE_INACTIVE,
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STATE_START2_SPACE,
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STATE_START2_MARK,
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STATE_MARKSPACE,
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STATE_TRAILER_MARK,
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};
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static char *st_name[] = {
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"Inactive",
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"start2 sapce",
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"start2 mark",
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"mark",
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"space",
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"trailer"
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};
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struct rc5_code {
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u8 address;
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u8 command;
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};
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struct decoder_data {
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struct list_head list;
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struct ir_input_dev *ir_dev;
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int enabled:1;
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/* State machine control */
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enum rc5_state state;
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struct rc5_code rc5_code;
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unsigned n_half;
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unsigned count;
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};
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/**
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* get_decoder_data() - gets decoder data
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* @input_dev: input device
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*
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* Returns the struct decoder_data that corresponds to a device
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*/
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static struct decoder_data *get_decoder_data(struct ir_input_dev *ir_dev)
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{
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struct decoder_data *data = NULL;
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spin_lock(&decoder_lock);
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list_for_each_entry(data, &decoder_list, list) {
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if (data->ir_dev == ir_dev)
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break;
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}
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spin_unlock(&decoder_lock);
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return data;
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}
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static ssize_t store_enabled(struct device *d,
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struct device_attribute *mattr,
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const char *buf,
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size_t len)
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{
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unsigned long value;
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struct ir_input_dev *ir_dev = dev_get_drvdata(d);
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struct decoder_data *data = get_decoder_data(ir_dev);
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if (!data)
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return -EINVAL;
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if (strict_strtoul(buf, 10, &value) || value > 1)
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return -EINVAL;
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data->enabled = value;
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return len;
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}
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static ssize_t show_enabled(struct device *d,
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struct device_attribute *mattr, char *buf)
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{
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struct ir_input_dev *ir_dev = dev_get_drvdata(d);
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struct decoder_data *data = get_decoder_data(ir_dev);
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if (!data)
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return -EINVAL;
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if (data->enabled)
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return sprintf(buf, "1\n");
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else
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return sprintf(buf, "0\n");
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}
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static DEVICE_ATTR(enabled, S_IRUGO | S_IWUSR, show_enabled, store_enabled);
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static struct attribute *decoder_attributes[] = {
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&dev_attr_enabled.attr,
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NULL
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};
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static struct attribute_group decoder_attribute_group = {
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.name = "rc5_decoder",
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.attrs = decoder_attributes,
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};
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/**
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* handle_event() - Decode one RC-5 pulse or space
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* @input_dev: the struct input_dev descriptor of the device
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* @ev: event array with type/duration of pulse/space
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*
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* This function returns -EINVAL if the pulse violates the state machine
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*/
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static int handle_event(struct input_dev *input_dev,
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struct ir_raw_event *ev)
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{
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struct decoder_data *data;
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struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
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int bit, last_bit, n_half;
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data = get_decoder_data(ir_dev);
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if (!data)
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return -EINVAL;
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/* Except for the initial event, what matters is the previous bit */
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bit = (ev->type & IR_PULSE) ? 1 : 0;
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last_bit = !bit;
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/* Discards spurious space last_bits when inactive */
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/* Very long delays are considered as start events */
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if (ev->delta.tv_nsec > RC5_DURATION + RC5_HALFBIT / 2)
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data->state = STATE_INACTIVE;
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if (ev->type & IR_START_EVENT)
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data->state = STATE_INACTIVE;
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switch (data->state) {
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case STATE_INACTIVE:
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IR_dprintk(1, "currently inative. Received bit (%s) @%luus\n",
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last_bit ? "pulse" : "space",
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(ev->delta.tv_nsec + 500) / 1000);
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/* Discards the initial start space */
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if (bit)
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return 0;
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data->count = 0;
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data->n_half = 0;
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memset (&data->rc5_code, 0, sizeof(data->rc5_code));
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data->state = STATE_START2_SPACE;
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return 0;
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case STATE_START2_SPACE:
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if (last_bit)
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goto err;
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if (!is_rc5_halfbit(ev->delta.tv_nsec))
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goto err;
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data->state = STATE_START2_MARK;
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return 0;
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case STATE_START2_MARK:
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if (!last_bit)
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goto err;
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if (!is_rc5_halfbit(ev->delta.tv_nsec))
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goto err;
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data->state = STATE_MARKSPACE;
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return 0;
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case STATE_MARKSPACE:
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n_half = n_half(ev->delta.tv_nsec);
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if (n_half < 1 || n_half > 3) {
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IR_dprintk(1, "Decode failed at %d-th bit (%s) @%luus\n",
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data->count,
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last_bit ? "pulse" : "space",
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(ev->delta.tv_nsec + 500) / 1000);
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printk("%d halves\n", n_half);
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goto err2;
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}
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data->n_half += n_half;
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if (!last_bit)
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return 0;
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/* Got one complete mark/space cycle */
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bit = ((data->count + 1) * 2)/ data->n_half;
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printk("%d halves, %d bits\n", n_half, bit);
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#if 1 /* SANITY check - while testing the decoder */
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if (bit > 1) {
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IR_dprintk(1, "Decoder HAS failed at %d-th bit (%s) @%luus\n",
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data->count,
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last_bit ? "pulse" : "space",
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(ev->delta.tv_nsec + 500) / 1000);
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goto err2;
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}
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#endif
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/* Ok, we've got a valid bit. proccess it */
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if (bit) {
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int shift = data->count;
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/*
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* RC-5 transmit bytes on this temporal order:
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* address | not address | command | not command
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*/
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if (shift < 8) {
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data->rc5_code.address |= 1 << shift;
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} else {
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data->rc5_code.command |= 1 << (shift - 8);
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}
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}
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IR_dprintk(1, "RC-5: bit #%d: %d (%d)\n",
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data->count, bit, data->n_half);
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if (++data->count >= RC5_NBITS) {
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u32 scancode;
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scancode = data->rc5_code.address << 8 |
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data->rc5_code.command;
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IR_dprintk(1, "RC-5 scancode 0x%04x\n", scancode);
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ir_keydown(input_dev, scancode, 0);
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data->state = STATE_TRAILER_MARK;
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}
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return 0;
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case STATE_TRAILER_MARK:
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if (!last_bit)
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goto err;
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data->state = STATE_INACTIVE;
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return 0;
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}
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err:
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IR_dprintk(1, "RC-5 decoded failed at state %s (%s) @ %luus\n",
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st_name[data->state],
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bit ? "pulse" : "space",
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(ev->delta.tv_nsec + 500) / 1000);
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err2:
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data->state = STATE_INACTIVE;
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return -EINVAL;
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}
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/**
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* ir_rc5_decode() - Decodes all RC-5 pulsecodes on a given array
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* @input_dev: the struct input_dev descriptor of the device
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* @evs: event array with type/duration of pulse/space
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* @len: length of the array
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* This function returns the number of decoded pulses
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*/
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static int ir_rc5_decode(struct input_dev *input_dev,
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struct ir_raw_event *evs,
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int len)
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{
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struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
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struct decoder_data *data;
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int pos = 0;
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int rc = 0;
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data = get_decoder_data(ir_dev);
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if (!data || !data->enabled)
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return 0;
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for (pos = 0; pos < len; pos++)
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handle_event(input_dev, &evs[pos]);
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return rc;
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}
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static int ir_rc5_register(struct input_dev *input_dev)
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{
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struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
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struct decoder_data *data;
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int rc;
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rc = sysfs_create_group(&ir_dev->dev.kobj, &decoder_attribute_group);
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if (rc < 0)
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return rc;
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data = kzalloc(sizeof(*data), GFP_KERNEL);
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if (!data) {
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sysfs_remove_group(&ir_dev->dev.kobj, &decoder_attribute_group);
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return -ENOMEM;
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}
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data->ir_dev = ir_dev;
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data->enabled = 1;
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spin_lock(&decoder_lock);
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list_add_tail(&data->list, &decoder_list);
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spin_unlock(&decoder_lock);
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return 0;
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}
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static int ir_rc5_unregister(struct input_dev *input_dev)
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{
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struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
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static struct decoder_data *data;
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data = get_decoder_data(ir_dev);
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if (!data)
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return 0;
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sysfs_remove_group(&ir_dev->dev.kobj, &decoder_attribute_group);
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spin_lock(&decoder_lock);
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list_del(&data->list);
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spin_unlock(&decoder_lock);
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return 0;
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}
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static struct ir_raw_handler rc5_handler = {
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.decode = ir_rc5_decode,
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.raw_register = ir_rc5_register,
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.raw_unregister = ir_rc5_unregister,
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};
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static int __init ir_rc5_decode_init(void)
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{
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ir_raw_handler_register(&rc5_handler);
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printk(KERN_INFO "IR RC-5 protocol handler initialized\n");
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return 0;
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}
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static void __exit ir_rc5_decode_exit(void)
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{
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ir_raw_handler_unregister(&rc5_handler);
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}
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module_init(ir_rc5_decode_init);
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module_exit(ir_rc5_decode_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@redhat.com>");
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MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
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MODULE_DESCRIPTION("RC-5 IR protocol decoder");
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