2010-04-04 21:27:20 +08:00
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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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2010-04-06 13:29:42 +08:00
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* It considers a carrier of 36 kHz, with a total of 14 bits, where
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* the first two bits are start bits, and a third one is a filing bit
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2010-04-04 21:27:20 +08:00
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*/
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#include <media/ir-core.h>
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2010-04-06 13:29:42 +08:00
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static unsigned int ir_rc5_remote_gap = 888888;
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2010-04-04 21:27:20 +08:00
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2010-04-06 13:29:42 +08:00
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#define RC5_NBITS 14
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#define RC5_BIT (ir_rc5_remote_gap * 2)
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#define RC5_DURATION (ir_rc5_remote_gap * RC5_NBITS)
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2010-04-04 21:27:20 +08:00
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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_MARKSPACE,
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2010-04-06 13:29:42 +08:00
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STATE_TRAILER,
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2010-04-04 21:27:20 +08:00
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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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2010-04-06 13:29:42 +08:00
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unsigned code, elapsed, last_bit, last_code;
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2010-04-04 21:27:20 +08:00
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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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2010-04-04 21:44:51 +08:00
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static int ir_rc5_decode(struct input_dev *input_dev,
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2010-04-04 21:27:20 +08:00
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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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2010-04-06 13:29:42 +08:00
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int is_pulse, scancode, delta, toggle;
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2010-04-04 21:27:20 +08:00
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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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2010-04-05 01:45:04 +08:00
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if (!data->enabled)
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return 0;
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2010-04-06 13:29:42 +08:00
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delta = DIV_ROUND_CLOSEST(ev->delta.tv_nsec, ir_rc5_remote_gap);
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2010-04-04 21:27:20 +08:00
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2010-04-06 13:29:42 +08:00
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/* The duration time refers to the last bit time */
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is_pulse = (ev->type & IR_PULSE) ? 1 : 0;
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2010-04-04 21:27:20 +08:00
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/* Very long delays are considered as start events */
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2010-04-06 13:29:42 +08:00
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if (delta > RC5_DURATION || (ev->type & IR_START_EVENT))
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2010-04-04 21:27:20 +08:00
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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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2010-04-06 13:29:42 +08:00
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IR_dprintk(2, "currently inative. Start bit (%s) @%uus\n",
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is_pulse ? "pulse" : "space",
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(unsigned)(ev->delta.tv_nsec + 500) / 1000);
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2010-04-04 21:27:20 +08:00
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/* Discards the initial start space */
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2010-04-06 13:29:42 +08:00
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if (!is_pulse)
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2010-04-04 21:27:20 +08:00
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goto err;
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2010-04-06 13:29:42 +08:00
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data->code = 1;
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data->last_bit = 1;
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data->elapsed = 0;
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memset(&data->rc5_code, 0, sizeof(data->rc5_code));
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2010-04-04 21:27:20 +08:00
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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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2010-04-06 13:29:42 +08:00
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if (delta != 1)
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data->last_bit = data->last_bit ? 0 : 1;
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2010-04-04 21:27:20 +08:00
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2010-04-06 13:29:42 +08:00
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data->elapsed += delta;
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2010-04-04 21:27:20 +08:00
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2010-04-06 13:29:42 +08:00
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if ((data->elapsed % 2) == 1)
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return 0;
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2010-04-04 21:27:20 +08:00
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2010-04-06 13:29:42 +08:00
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data->code <<= 1;
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data->code |= data->last_bit;
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2010-04-04 21:27:20 +08:00
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2010-04-06 13:29:42 +08:00
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/* Fill the 2 unused bits at the command with 0 */
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if (data->elapsed / 2 == 6)
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data->code <<= 2;
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2010-04-04 21:27:20 +08:00
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2010-04-06 13:29:42 +08:00
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if (data->elapsed >= (RC5_NBITS - 1) * 2) {
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scancode = data->code;
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2010-04-04 21:27:20 +08:00
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2010-04-06 13:29:42 +08:00
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/* Check for the start bits */
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if ((scancode & 0xc000) != 0xc000) {
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IR_dprintk(1, "Code 0x%04x doesn't have two start bits. It is not RC-5\n", scancode);
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goto err;
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2010-04-04 21:27:20 +08:00
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}
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2010-04-06 13:29:42 +08:00
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toggle = (scancode & 0x2000) ? 1 : 0;
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if (scancode == data->last_code) {
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IR_dprintk(1, "RC-5 repeat\n");
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ir_repeat(input_dev);
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} else {
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data->last_code = scancode;
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scancode &= 0x1fff;
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IR_dprintk(1, "RC-5 scancode 0x%04x\n", scancode);
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2010-04-04 21:27:20 +08:00
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2010-04-06 13:29:42 +08:00
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ir_keydown(input_dev, scancode, 0);
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}
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data->state = STATE_TRAILER;
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2010-04-04 21:27:20 +08:00
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}
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return 0;
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2010-04-06 13:29:42 +08:00
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case STATE_TRAILER:
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2010-04-04 21:27:20 +08:00
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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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2010-04-06 13:29:42 +08:00
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IR_dprintk(1, "RC-5 decoded failed at %s @ %luus\n",
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is_pulse ? "pulse" : "space",
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2010-04-04 21:27:20 +08:00
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(ev->delta.tv_nsec + 500) / 1000);
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data->state = STATE_INACTIVE;
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return -EINVAL;
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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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