V4L/DVB: IR/streamzap: functional in-kernel decoding

This patch makes in-kernel decoding with the stock Streamzap PC Remote
work out of the box. There are quite a few things going on in this
patch, all related to getting this working:

1) I had to enable reporting of a long space at the end of each signal,
   or I had weird buffering and keybounce issues.

2) The keymap has been reworked slightly to match actual decoded values,
   the first edition was missing the pre-data bits present in the lirc
   config file for this remote.

3) There's a whole new decoder included, specifically for the
   not-quite-RC5 15-bit protocol variant used by the Streamzap PC
   Remote. The decoder, while usable with other recievers (tested with
   an mceusb receiver), will only be loaded by the streamzap driver, as
   its likely not of use in almost all other situations. This can be
   revisited if/when all keytable loading (and disabling of unneeded
   protocol decoder engines) is moved to userspace, but for now, I think
   this makes the most sense.

Note that I did try to enable handling the streamzap RC5-ish protocol in
the current RC5 decoder, but there's no particularly easy way to tell if
its 14-bit RC5 or 15-bit Streamzap until we see bit 14, and even then,
in testing an attempted decoder merge, only 2/3 of the keys were
properly recognized as being the 15-bit variant and decoded correctly,
the rest were close enough to compliant with 14-bit that they were
decoded as such (but they have overlap with one another, and thus we
can't just shrug and use the 14-bit decoded values).

Also of note in this patch is the removal of the streamzap driver's
internal delay buffer. Per discussion w/Christoph, it shouldn't be
needed by lirc any longer anyway, and it doesn't seem to make any
difference to the in-kernel decoder engine. That being the case, I'm
yanking it all out, as it greatly simplifies the driver code.

Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 153 insertions, 0 deletions

diff --git a/drivers/media/IR/ir-rc5-sz-decoder.c b/drivers/media/IR/ir-rc5-sz-decoder.c
new file mode 100644
index 000000000000..68f11d6acd5b
--- /dev/null
+++ b/drivers/media/IR/ir-rc5-sz-decoder.c
@@ -0,0 +1,153 @@
+/* ir-rc5-sz-decoder.c - handle RC5 Streamzap IR Pulse/Space protocol
+ *
+ * Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com>
+ * Copyright (C) 2010 by Jarod Wilson <jarod@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.
+ */
+
+/*
+ * This code handles the 15 bit RC5-ish protocol used by the Streamzap
+ * PC Remote.
+ * It considers a carrier of 36 kHz, with a total of 15 bits, where
+ * the first two bits are start bits, and a third one is a filing bit
+ */
+
+#include "ir-core-priv.h"
+
+#define RC5_SZ_NBITS            15
+#define RC5_UNIT                888888 /* ns */
+#define RC5_BIT_START           (1 * RC5_UNIT)
+#define RC5_BIT_END             (1 * RC5_UNIT)
+
+enum rc5_sz_state {
+        STATE_INACTIVE,
+        STATE_BIT_START,
+        STATE_BIT_END,
+        STATE_FINISHED,
+};
+
+/**
+ * ir_rc5_sz_decode() - Decode one RC-5 Streamzap 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_rc5_sz_decode(struct input_dev *input_dev, struct ir_raw_event ev)
+{
+        struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
+        struct rc5_sz_dec *data = &ir_dev->raw->rc5_sz;
+        u8 toggle, command, system;
+        u32 scancode;
+
+        if (!(ir_dev->raw->enabled_protocols & IR_TYPE_RC5_SZ))
+                return 0;
+
+        if (IS_RESET(ev)) {
+                data->state = STATE_INACTIVE;
+                return 0;
+        }
+
+        if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
+                goto out;
+
+again:
+        IR_dprintk(2, "RC5-sz decode started at state %i (%uus %s)\n",
+                   data->state, TO_US(ev.duration), TO_STR(ev.pulse));
+
+        if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
+                return 0;
+
+        switch (data->state) {
+
+        case STATE_INACTIVE:
+                if (!ev.pulse)
+                        break;
+
+                data->state = STATE_BIT_START;
+                data->count = 1;
+                data->wanted_bits = RC5_SZ_NBITS;
+                decrease_duration(&ev, RC5_BIT_START);
+                goto again;
+
+        case STATE_BIT_START:
+                if (!eq_margin(ev.duration, RC5_BIT_START, RC5_UNIT / 2))
+                        break;
+
+                data->bits <<= 1;
+                if (!ev.pulse)
+                        data->bits |= 1;
+                data->count++;
+                data->state = STATE_BIT_END;
+                return 0;
+
+        case STATE_BIT_END:
+                if (!is_transition(&ev, &ir_dev->raw->prev_ev))
+                        break;
+
+                if (data->count == data->wanted_bits)
+                        data->state = STATE_FINISHED;
+                else
+                        data->state = STATE_BIT_START;
+
+                decrease_duration(&ev, RC5_BIT_END);
+                goto again;
+
+        case STATE_FINISHED:
+                if (ev.pulse)
+                        break;
+
+                /* RC5-sz */
+                command  = (data->bits & 0x0003F) >> 0;
+                system   = (data->bits & 0x02FC0) >> 6;
+                toggle   = (data->bits & 0x01000) ? 1 : 0;
+                scancode = system << 6 | command;
+
+                IR_dprintk(1, "RC5-sz scancode 0x%04x (toggle: %u)\n",
+                           scancode, toggle);
+
+                ir_keydown(input_dev, scancode, toggle);
+                data->state = STATE_INACTIVE;
+                return 0;
+        }
+
+out:
+        IR_dprintk(1, "RC5-sz 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 struct ir_raw_handler rc5_sz_handler = {
+        .protocols      = IR_TYPE_RC5_SZ,
+        .decode         = ir_rc5_sz_decode,
+};
+
+static int __init ir_rc5_sz_decode_init(void)
+{
+        ir_raw_handler_register(&rc5_sz_handler);
+
+        printk(KERN_INFO "IR RC5 (streamzap) protocol handler initialized\n");
+        return 0;
+}
+
+static void __exit ir_rc5_sz_decode_exit(void)
+{
+        ir_raw_handler_unregister(&rc5_sz_handler);
+}
+
+module_init(ir_rc5_sz_decode_init);
+module_exit(ir_rc5_sz_decode_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Jarod Wilson <jarod@redhat.com>");
+MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
+MODULE_DESCRIPTION("RC5 (streamzap) IR protocol decoder");