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path: root/drivers/media/rc/ir-nec-decoder.c
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Diffstat (limited to 'drivers/media/rc/ir-nec-decoder.c')
-rw-r--r--drivers/media/rc/ir-nec-decoder.c220
1 files changed, 220 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 000000000000..7b58b4a1729b
--- /dev/null
+++ b/drivers/media/rc/ir-nec-decoder.c
@@ -0,0 +1,220 @@
+/* ir-nec-decoder.c - handle NEC IR Pulse/Space protocol
+ *
+ * Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com>
+ *
+ * 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 <linux/bitrev.h>
+#include "rc-core-priv.h"
+
+#define NEC_NBITS 32
+#define NEC_UNIT 562500 /* ns */
+#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
+ * @duration: 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;
+ u8 address, not_address, command, not_command;
+
+ if (!(dev->raw->enabled_protocols & RC_TYPE_NEC))
+ return 0;
+
+ if (!is_timing_event(ev)) {
+ if (ev.reset)
+ data->state = STATE_INACTIVE;
+ return 0;
+ }
+
+ IR_dprintk(2, "NEC decode started at state %d (%uus %s)\n",
+ data->state, TO_US(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 / 2)) {
+ data->state = STATE_BIT_PULSE;
+ return 0;
+ } else if (eq_margin(ev.duration, NEC_REPEAT_SPACE, NEC_UNIT / 2)) {
+ if (!dev->keypressed) {
+ IR_dprintk(1, "Discarding last key repeat: event after key up\n");
+ } else {
+ rc_repeat(dev);
+ IR_dprintk(1, "Repeat last key\n");
+ 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)) {
+ IR_dprintk(1, "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;
+
+ 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);
+
+ if ((command ^ not_command) != 0xff) {
+ IR_dprintk(1, "NEC checksum error: received 0x%08x\n",
+ data->bits);
+ break;
+ }
+
+ if ((address ^ not_address) != 0xff) {
+ /* Extended NEC */
+ scancode = address << 16 |
+ not_address << 8 |
+ command;
+ IR_dprintk(1, "NEC (Ext) scancode 0x%06x\n", scancode);
+ } else {
+ /* Normal NEC */
+ scancode = address << 8 | command;
+ IR_dprintk(1, "NEC scancode 0x%04x\n", scancode);
+ }
+
+ if (data->is_nec_x)
+ data->necx_repeat = true;
+
+ rc_keydown(dev, scancode, 0);
+ data->state = STATE_INACTIVE;
+ return 0;
+ }
+
+ IR_dprintk(1, "NEC decode failed at state %d (%uus %s)\n",
+ data->state, TO_US(ev.duration), TO_STR(ev.pulse));
+ data->state = STATE_INACTIVE;
+ return -EINVAL;
+}
+
+static struct ir_raw_handler nec_handler = {
+ .protocols = RC_TYPE_NEC,
+ .decode = ir_nec_decode,
+};
+
+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");
+MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@redhat.com>");
+MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
+MODULE_DESCRIPTION("NEC IR protocol decoder");