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-rw-r--r--drivers/media/rc/ir-nec-decoder.c278
1 files changed, 278 insertions, 0 deletions
diff --git a/drivers/media/rc/ir-nec-decoder.c b/drivers/media/rc/ir-nec-decoder.c
new file mode 100644
index 000000000..37b99432a
--- /dev/null
+++ b/drivers/media/rc/ir-nec-decoder.c
@@ -0,0 +1,278 @@
+// SPDX-License-Identifier: GPL-2.0
+// ir-nec-decoder.c - handle NEC IR Pulse/Space protocol
+//
+// Copyright (C) 2010 by Mauro Carvalho Chehab
+
+#include <linux/bitrev.h>
+#include <linux/module.h>
+#include "rc-core-priv.h"
+
+#define NEC_NBITS 32
+#define NEC_UNIT 563 /* us */
+#define NEC_HEADER_PULSE (16 * NEC_UNIT)
+#define NECX_HEADER_PULSE (8 * NEC_UNIT) /* Less common NEC variant */
+#define NEC_HEADER_SPACE (8 * NEC_UNIT)
+#define NEC_REPEAT_SPACE (4 * NEC_UNIT)
+#define NEC_BIT_PULSE (1 * NEC_UNIT)
+#define NEC_BIT_0_SPACE (1 * NEC_UNIT)
+#define NEC_BIT_1_SPACE (3 * NEC_UNIT)
+#define NEC_TRAILER_PULSE (1 * NEC_UNIT)
+#define NEC_TRAILER_SPACE (10 * NEC_UNIT) /* even longer in reality */
+#define NECX_REPEAT_BITS 1
+
+enum nec_state {
+ STATE_INACTIVE,
+ STATE_HEADER_SPACE,
+ STATE_BIT_PULSE,
+ STATE_BIT_SPACE,
+ STATE_TRAILER_PULSE,
+ STATE_TRAILER_SPACE,
+};
+
+/**
+ * ir_nec_decode() - Decode one NEC pulse or space
+ * @dev: the struct rc_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_nec_decode(struct rc_dev *dev, struct ir_raw_event ev)
+{
+ struct nec_dec *data = &dev->raw->nec;
+ u32 scancode;
+ enum rc_proto rc_proto;
+ u8 address, not_address, command, not_command;
+
+ if (!is_timing_event(ev)) {
+ if (ev.overflow)
+ data->state = STATE_INACTIVE;
+ return 0;
+ }
+
+ dev_dbg(&dev->dev, "NEC decode started at state %d (%uus %s)\n",
+ data->state, ev.duration, TO_STR(ev.pulse));
+
+ switch (data->state) {
+
+ case STATE_INACTIVE:
+ if (!ev.pulse)
+ break;
+
+ if (eq_margin(ev.duration, NEC_HEADER_PULSE, NEC_UNIT * 2)) {
+ data->is_nec_x = false;
+ data->necx_repeat = false;
+ } else if (eq_margin(ev.duration, NECX_HEADER_PULSE, NEC_UNIT / 2))
+ data->is_nec_x = true;
+ else
+ break;
+
+ data->count = 0;
+ data->state = STATE_HEADER_SPACE;
+ return 0;
+
+ case STATE_HEADER_SPACE:
+ if (ev.pulse)
+ break;
+
+ if (eq_margin(ev.duration, NEC_HEADER_SPACE, NEC_UNIT)) {
+ data->state = STATE_BIT_PULSE;
+ return 0;
+ } else if (eq_margin(ev.duration, NEC_REPEAT_SPACE, NEC_UNIT / 2)) {
+ data->state = STATE_TRAILER_PULSE;
+ return 0;
+ }
+
+ break;
+
+ case STATE_BIT_PULSE:
+ if (!ev.pulse)
+ break;
+
+ if (!eq_margin(ev.duration, NEC_BIT_PULSE, NEC_UNIT / 2))
+ break;
+
+ data->state = STATE_BIT_SPACE;
+ return 0;
+
+ case STATE_BIT_SPACE:
+ if (ev.pulse)
+ break;
+
+ if (data->necx_repeat && data->count == NECX_REPEAT_BITS &&
+ geq_margin(ev.duration, NEC_TRAILER_SPACE, NEC_UNIT / 2)) {
+ dev_dbg(&dev->dev, "Repeat last key\n");
+ rc_repeat(dev);
+ data->state = STATE_INACTIVE;
+ return 0;
+ } else if (data->count > NECX_REPEAT_BITS)
+ data->necx_repeat = false;
+
+ data->bits <<= 1;
+ if (eq_margin(ev.duration, NEC_BIT_1_SPACE, NEC_UNIT / 2))
+ data->bits |= 1;
+ else if (!eq_margin(ev.duration, NEC_BIT_0_SPACE, NEC_UNIT / 2))
+ break;
+ data->count++;
+
+ if (data->count == NEC_NBITS)
+ data->state = STATE_TRAILER_PULSE;
+ else
+ data->state = STATE_BIT_PULSE;
+
+ return 0;
+
+ case STATE_TRAILER_PULSE:
+ if (!ev.pulse)
+ break;
+
+ if (!eq_margin(ev.duration, NEC_TRAILER_PULSE, NEC_UNIT / 2))
+ break;
+
+ data->state = STATE_TRAILER_SPACE;
+ return 0;
+
+ case STATE_TRAILER_SPACE:
+ if (ev.pulse)
+ break;
+
+ if (!geq_margin(ev.duration, NEC_TRAILER_SPACE, NEC_UNIT / 2))
+ break;
+
+ if (data->count == NEC_NBITS) {
+ address = bitrev8((data->bits >> 24) & 0xff);
+ not_address = bitrev8((data->bits >> 16) & 0xff);
+ command = bitrev8((data->bits >> 8) & 0xff);
+ not_command = bitrev8((data->bits >> 0) & 0xff);
+
+ scancode = ir_nec_bytes_to_scancode(address,
+ not_address,
+ command,
+ not_command,
+ &rc_proto);
+
+ if (data->is_nec_x)
+ data->necx_repeat = true;
+
+ rc_keydown(dev, rc_proto, scancode, 0);
+ } else {
+ rc_repeat(dev);
+ }
+
+ data->state = STATE_INACTIVE;
+ return 0;
+ }
+
+ dev_dbg(&dev->dev, "NEC decode failed at count %d state %d (%uus %s)\n",
+ data->count, data->state, ev.duration, TO_STR(ev.pulse));
+ data->state = STATE_INACTIVE;
+ return -EINVAL;
+}
+
+/**
+ * ir_nec_scancode_to_raw() - encode an NEC scancode ready for modulation.
+ * @protocol: specific protocol to use
+ * @scancode: a single NEC scancode.
+ */
+static u32 ir_nec_scancode_to_raw(enum rc_proto protocol, u32 scancode)
+{
+ unsigned int addr, addr_inv, data, data_inv;
+
+ data = scancode & 0xff;
+
+ if (protocol == RC_PROTO_NEC32) {
+ /* 32-bit NEC (used by Apple and TiVo remotes) */
+ /* scan encoding: aaAAddDD */
+ addr_inv = (scancode >> 24) & 0xff;
+ addr = (scancode >> 16) & 0xff;
+ data_inv = (scancode >> 8) & 0xff;
+ } else if (protocol == RC_PROTO_NECX) {
+ /* Extended NEC */
+ /* scan encoding AAaaDD */
+ addr = (scancode >> 16) & 0xff;
+ addr_inv = (scancode >> 8) & 0xff;
+ data_inv = data ^ 0xff;
+ } else {
+ /* Normal NEC */
+ /* scan encoding: AADD */
+ addr = (scancode >> 8) & 0xff;
+ addr_inv = addr ^ 0xff;
+ data_inv = data ^ 0xff;
+ }
+
+ /* raw encoding: ddDDaaAA */
+ return data_inv << 24 |
+ data << 16 |
+ addr_inv << 8 |
+ addr;
+}
+
+static const struct ir_raw_timings_pd ir_nec_timings = {
+ .header_pulse = NEC_HEADER_PULSE,
+ .header_space = NEC_HEADER_SPACE,
+ .bit_pulse = NEC_BIT_PULSE,
+ .bit_space[0] = NEC_BIT_0_SPACE,
+ .bit_space[1] = NEC_BIT_1_SPACE,
+ .trailer_pulse = NEC_TRAILER_PULSE,
+ .trailer_space = NEC_TRAILER_SPACE,
+ .msb_first = 0,
+};
+
+/**
+ * ir_nec_encode() - Encode a scancode as a stream of raw events
+ *
+ * @protocol: protocol to encode
+ * @scancode: scancode to encode
+ * @events: array of raw ir events to write into
+ * @max: maximum size of @events
+ *
+ * Returns: The number of events written.
+ * -ENOBUFS if there isn't enough space in the array to fit the
+ * encoding. In this case all @max events will have been written.
+ */
+static int ir_nec_encode(enum rc_proto protocol, u32 scancode,
+ struct ir_raw_event *events, unsigned int max)
+{
+ struct ir_raw_event *e = events;
+ int ret;
+ u32 raw;
+
+ /* Convert a NEC scancode to raw NEC data */
+ raw = ir_nec_scancode_to_raw(protocol, scancode);
+
+ /* Modulate the raw data using a pulse distance modulation */
+ ret = ir_raw_gen_pd(&e, max, &ir_nec_timings, NEC_NBITS, raw);
+ if (ret < 0)
+ return ret;
+
+ return e - events;
+}
+
+static struct ir_raw_handler nec_handler = {
+ .protocols = RC_PROTO_BIT_NEC | RC_PROTO_BIT_NECX |
+ RC_PROTO_BIT_NEC32,
+ .decode = ir_nec_decode,
+ .encode = ir_nec_encode,
+ .carrier = 38000,
+ .min_timeout = NEC_TRAILER_SPACE,
+};
+
+static int __init ir_nec_decode_init(void)
+{
+ ir_raw_handler_register(&nec_handler);
+
+ printk(KERN_INFO "IR NEC protocol handler initialized\n");
+ return 0;
+}
+
+static void __exit ir_nec_decode_exit(void)
+{
+ ir_raw_handler_unregister(&nec_handler);
+}
+
+module_init(ir_nec_decode_init);
+module_exit(ir_nec_decode_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Mauro Carvalho Chehab");
+MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
+MODULE_DESCRIPTION("NEC IR protocol decoder");