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");