diff options
Diffstat (limited to 'drivers/media/IR/ir-rc6-decoder.c')
| -rw-r--r-- | drivers/media/IR/ir-rc6-decoder.c | 419 |
1 files changed, 419 insertions, 0 deletions
diff --git a/drivers/media/IR/ir-rc6-decoder.c b/drivers/media/IR/ir-rc6-decoder.c new file mode 100644 index 000000000000..2bf479f4f1bc --- /dev/null +++ b/drivers/media/IR/ir-rc6-decoder.c @@ -0,0 +1,419 @@ +/* ir-rc6-decoder.c - A decoder for the RC6 IR protocol + * + * Copyright (C) 2010 by David Härdeman <david@hardeman.nu> + * + * 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) + */ + +#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 +#define RC6_PREFIX_PULSE (6 * RC6_UNIT) +#define RC6_PREFIX_SPACE (2 * RC6_UNIT) +#define RC6_BIT_START (1 * RC6_UNIT) +#define RC6_BIT_END (1 * RC6_UNIT) +#define RC6_TOGGLE_START (2 * RC6_UNIT) +#define RC6_TOGGLE_END (2 * RC6_UNIT) +#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 */ + +/* 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; + struct ir_raw_event prev_ev; + 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 + * @ev: the struct ir_raw_event descriptor of the pulse/space + * + * This function returns -EINVAL if the pulse violates the state machine + */ +static int ir_rc6_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); + u32 scancode; + u8 toggle; + + data = get_decoder_data(ir_dev); + if (!data) + return -EINVAL; + + if (!data->enabled) + return 0; + + if (IS_RESET(ev)) { + data->state = STATE_INACTIVE; + return 0; + } + + if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) + goto out; + +again: + IR_dprintk(2, "RC6 decode started at state %i (%uus %s)\n", + data->state, TO_US(ev.duration), TO_STR(ev.pulse)); + + if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) + return 0; + + switch (data->state) { + + case STATE_INACTIVE: + if (!ev.pulse) + break; + + /* Note: larger margin on first pulse since each RC6_UNIT + is quite short and some hardware takes some time to + adjust to the signal */ + if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT)) + break; + + data->state = STATE_PREFIX_SPACE; + data->count = 0; + return 0; + + case STATE_PREFIX_SPACE: + if (ev.pulse) + break; + + if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2)) + break; + + data->state = STATE_HEADER_BIT_START; + return 0; + + case STATE_HEADER_BIT_START: + if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) + break; + + data->header <<= 1; + if (ev.pulse) + data->header |= 1; + data->count++; + data->prev_ev = ev; + data->state = STATE_HEADER_BIT_END; + return 0; + + case STATE_HEADER_BIT_END: + if (!is_transition(&ev, &data->prev_ev)) + break; + + if (data->count == RC6_HEADER_NBITS) + data->state = STATE_TOGGLE_START; + else + data->state = STATE_HEADER_BIT_START; + + decrease_duration(&ev, RC6_BIT_END); + goto again; + + case STATE_TOGGLE_START: + if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2)) + break; + + data->toggle = ev.pulse; + data->prev_ev = ev; + data->state = STATE_TOGGLE_END; + return 0; + + case STATE_TOGGLE_END: + if (!is_transition(&ev, &data->prev_ev) || + !geq_margin(ev.duration, RC6_TOGGLE_END, RC6_UNIT / 2)) + break; + + if (!(data->header & RC6_STARTBIT_MASK)) { + IR_dprintk(1, "RC6 invalid start bit\n"); + break; + } + + data->state = STATE_BODY_BIT_START; + data->prev_ev = ev; + decrease_duration(&ev, RC6_TOGGLE_END); + data->count = 0; + + 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 */ + if ((!ev.pulse && !geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) || + geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) + 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; + + case STATE_BODY_BIT_START: + if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) + break; + + data->body <<= 1; + if (ev.pulse) + data->body |= 1; + data->count++; + data->prev_ev = ev; + + data->state = STATE_BODY_BIT_END; + return 0; + + case STATE_BODY_BIT_END: + if (!is_transition(&ev, &data->prev_ev)) + break; + + if (data->count == data->wanted_bits) + data->state = STATE_FINISHED; + else + data->state = STATE_BODY_BIT_START; + + decrease_duration(&ev, RC6_BIT_END); + goto again; + + case STATE_FINISHED: + if (ev.pulse) + break; + + 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; + } 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 (%uus %s)\n", + data->state, TO_US(ev.duration), TO_STR(ev.pulse)); + 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@hardeman.nu>"); +MODULE_DESCRIPTION("RC6 IR protocol decoder"); |