/* ir-rc5-decoder.c - handle RC-5 IR Pulse/Space protocol * * Copyright (C) 2010 by Mauro Carvalho Chehab * * 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. */ /* * This code only handles 14 bits RC-5 protocols. There are other variants * that use a different number of bits. This is currently unsupported * It considers a carrier of 36 kHz, with a total of 14 bits, where * the first two bits are start bits, and a third one is a filing bit */ #include static unsigned int ir_rc5_remote_gap = 888888; #define RC5_NBITS 14 #define RC5_BIT (ir_rc5_remote_gap * 2) #define RC5_DURATION (ir_rc5_remote_gap * RC5_NBITS) /* Used to register rc5_decoder clients */ static LIST_HEAD(decoder_list); static spinlock_t decoder_lock; enum rc5_state { STATE_INACTIVE, STATE_MARKSPACE, STATE_TRAILER, }; struct rc5_code { u8 address; u8 command; }; struct decoder_data { struct list_head list; struct ir_input_dev *ir_dev; int enabled:1; /* State machine control */ enum rc5_state state; struct rc5_code rc5_code; unsigned code, elapsed, last_bit, last_code; }; /** * 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 = "rc5_decoder", .attrs = decoder_attributes, }; /** * handle_event() - Decode one RC-5 pulse or space * @input_dev: the struct input_dev descriptor of the device * @ev: event array with type/duration of pulse/space * * This function returns -EINVAL if the pulse violates the state machine */ static int ir_rc5_decode(struct input_dev *input_dev, struct ir_raw_event *ev) { struct decoder_data *data; struct ir_input_dev *ir_dev = input_get_drvdata(input_dev); int is_pulse, scancode, delta, toggle; data = get_decoder_data(ir_dev); if (!data) return -EINVAL; if (!data->enabled) return 0; delta = DIV_ROUND_CLOSEST(ev->delta.tv_nsec, ir_rc5_remote_gap); /* The duration time refers to the last bit time */ is_pulse = (ev->type & IR_PULSE) ? 1 : 0; /* Very long delays are considered as start events */ if (delta > RC5_DURATION || (ev->type & IR_START_EVENT)) data->state = STATE_INACTIVE; switch (data->state) { case STATE_INACTIVE: IR_dprintk(2, "currently inative. Start bit (%s) @%uus\n", is_pulse ? "pulse" : "space", (unsigned)(ev->delta.tv_nsec + 500) / 1000); /* Discards the initial start space */ if (!is_pulse) goto err; data->code = 1; data->last_bit = 1; data->elapsed = 0; memset(&data->rc5_code, 0, sizeof(data->rc5_code)); data->state = STATE_MARKSPACE; return 0; case STATE_MARKSPACE: if (delta != 1) data->last_bit = data->last_bit ? 0 : 1; data->elapsed += delta; if ((data->elapsed % 2) == 1) return 0; data->code <<= 1; data->code |= data->last_bit; /* Fill the 2 unused bits at the command with 0 */ if (data->elapsed / 2 == 6) data->code <<= 2; if (data->elapsed >= (RC5_NBITS - 1) * 2) { scancode = data->code; /* Check for the start bits */ if ((scancode & 0xc000) != 0xc000) { IR_dprintk(1, "Code 0x%04x doesn't have two start bits. It is not RC-5\n", scancode); goto err; } toggle = (scancode & 0x2000) ? 1 : 0; if (scancode == data->last_code) { IR_dprintk(1, "RC-5 repeat\n"); ir_repeat(input_dev); } else { data->last_code = scancode; scancode &= 0x1fff; IR_dprintk(1, "RC-5 scancode 0x%04x\n", scancode); ir_keydown(input_dev, scancode, 0); } data->state = STATE_TRAILER; } return 0; case STATE_TRAILER: data->state = STATE_INACTIVE; return 0; } err: IR_dprintk(1, "RC-5 decoded failed at %s @ %luus\n", is_pulse ? "pulse" : "space", (ev->delta.tv_nsec + 500) / 1000); data->state = STATE_INACTIVE; return -EINVAL; } static int ir_rc5_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_rc5_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 rc5_handler = { .decode = ir_rc5_decode, .raw_register = ir_rc5_register, .raw_unregister = ir_rc5_unregister, }; static int __init ir_rc5_decode_init(void) { ir_raw_handler_register(&rc5_handler); printk(KERN_INFO "IR RC-5 protocol handler initialized\n"); return 0; } static void __exit ir_rc5_decode_exit(void) { ir_raw_handler_unregister(&rc5_handler); } module_init(ir_rc5_decode_init); module_exit(ir_rc5_decode_exit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Mauro Carvalho Chehab "); MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)"); MODULE_DESCRIPTION("RC-5 IR protocol decoder");