media: rc: add new imon protocol decoder and encoder

This makes it possible to use the various iMON remotes with any raw IR
RC device.

Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

8 files changed, 220 insertions, 5 deletions

diff --git a/drivers/media/rc/Kconfig b/drivers/media/rc/Kconfig
index 7ad05a6ef350..eb2c3b6eca7f 100644
--- a/drivers/media/rc/Kconfig
+++ b/drivers/media/rc/Kconfig
@@ -111,6 +111,15 @@ config IR_XMP_DECODER
         ---help---
            Enable this option if you have IR with XMP protocol, and
            if the IR is decoded in software
+
+config IR_IMON_DECODER
+        tristate "Enable IR raw decoder for the iMON protocol"
+        depends on RC_CORE
+        ---help---
+           Enable this option if you have iMON PAD or Antec Veris infrared
+           remote control and you would like to use it with a raw IR
+           receiver, or if you wish to use an encoder to transmit this IR.
+
 endif #RC_DECODERS
 
 menuconfig RC_DEVICES
diff --git a/drivers/media/rc/Makefile b/drivers/media/rc/Makefile
index e098e127b26a..2e1c87066f6c 100644
--- a/drivers/media/rc/Makefile
+++ b/drivers/media/rc/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_IR_SANYO_DECODER) += ir-sanyo-decoder.o
 obj-$(CONFIG_IR_SHARP_DECODER) += ir-sharp-decoder.o
 obj-$(CONFIG_IR_MCE_KBD_DECODER) += ir-mce_kbd-decoder.o
 obj-$(CONFIG_IR_XMP_DECODER) += ir-xmp-decoder.o
+obj-$(CONFIG_IR_IMON_DECODER) += ir-imon-decoder.o
 
 # stand-alone IR receivers/transmitters
 obj-$(CONFIG_RC_ATI_REMOTE) += ati_remote.o
diff --git a/drivers/media/rc/ir-imon-decoder.c b/drivers/media/rc/ir-imon-decoder.c
new file mode 100644
index 000000000000..a1ff06a26542
--- /dev/null
+++ b/drivers/media/rc/ir-imon-decoder.c
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: GPL-2.0+
+// ir-imon-decoder.c - handle iMon protocol
+//
+// Copyright (C) 2018 by Sean Young <sean@mess.org>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include "rc-core-priv.h"
+
+#define IMON_UNIT               415662 /* ns */
+#define IMON_BITS               30
+#define IMON_CHKBITS            (BIT(30) | BIT(25) | BIT(24) | BIT(22) | \
+                                 BIT(21) | BIT(20) | BIT(19) | BIT(18) | \
+                                 BIT(17) | BIT(16) | BIT(14) | BIT(13) | \
+                                 BIT(12) | BIT(11) | BIT(10) | BIT(9))
+
+/*
+ * This protocol has 30 bits. The format is one IMON_UNIT header pulse,
+ * followed by 30 bits. Each bit is one IMON_UNIT check field, and then
+ * one IMON_UNIT field with the actual bit (1=space, 0=pulse).
+ * The check field is always space for some bits, for others it is pulse if
+ * both the preceding and current bit are zero, else space. IMON_CHKBITS
+ * defines which bits are of type check.
+ *
+ * There is no way to distinguish an incomplete message from one where
+ * the lower bits are all set, iow. the last pulse is for the lowest
+ * bit which is 0.
+ */
+enum imon_state {
+        STATE_INACTIVE,
+        STATE_BIT_CHK,
+        STATE_BIT_START,
+        STATE_FINISHED
+};
+
+/**
+ * ir_imon_decode() - Decode one iMON 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_imon_decode(struct rc_dev *dev, struct ir_raw_event ev)
+{
+        struct imon_dec *data = &dev->raw->imon;
+
+        if (!is_timing_event(ev)) {
+                if (ev.reset)
+                        data->state = STATE_INACTIVE;
+                return 0;
+        }
+
+        dev_dbg(&dev->dev,
+                "iMON decode started at state %d bitno %d (%uus %s)\n",
+                data->state, data->count, TO_US(ev.duration),
+                TO_STR(ev.pulse));
+
+        for (;;) {
+                if (!geq_margin(ev.duration, IMON_UNIT, IMON_UNIT / 2))
+                        return 0;
+
+                decrease_duration(&ev, IMON_UNIT);
+
+                switch (data->state) {
+                case STATE_INACTIVE:
+                        if (ev.pulse) {
+                                data->state = STATE_BIT_CHK;
+                                data->bits = 0;
+                                data->count = IMON_BITS;
+                        }
+                        break;
+                case STATE_BIT_CHK:
+                        if (IMON_CHKBITS & BIT(data->count))
+                                data->last_chk = ev.pulse;
+                        else if (ev.pulse)
+                                goto err_out;
+                        data->state = STATE_BIT_START;
+                        break;
+                case STATE_BIT_START:
+                        data->bits <<= 1;
+                        if (!ev.pulse)
+                                data->bits |= 1;
+
+                        if (IMON_CHKBITS & BIT(data->count)) {
+                                if (data->last_chk != !(data->bits & 3))
+                                        goto err_out;
+                        }
+
+                        if (!data->count--)
+                                data->state = STATE_FINISHED;
+                        else
+                                data->state = STATE_BIT_CHK;
+                        break;
+                case STATE_FINISHED:
+                        if (ev.pulse)
+                                goto err_out;
+                        rc_keydown(dev, RC_PROTO_IMON, data->bits, 0);
+                        data->state = STATE_INACTIVE;
+                        break;
+                }
+        }
+
+err_out:
+        dev_dbg(&dev->dev,
+                "iMON decode failed at state %d bitno %d (%uus %s)\n",
+                data->state, data->count, TO_US(ev.duration),
+                TO_STR(ev.pulse));
+
+        data->state = STATE_INACTIVE;
+
+        return -EINVAL;
+}
+
+/**
+ * ir_imon_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_imon_encode(enum rc_proto protocol, u32 scancode,
+                          struct ir_raw_event *events, unsigned int max)
+{
+        struct ir_raw_event *e = events;
+        int i, pulse;
+
+        if (!max--)
+                return -ENOBUFS;
+        init_ir_raw_event_duration(e, 1, IMON_UNIT);
+
+        for (i = IMON_BITS; i >= 0; i--) {
+                if (BIT(i) & IMON_CHKBITS)
+                        pulse = !(scancode & (BIT(i) | BIT(i + 1)));
+                else
+                        pulse = 0;
+
+                if (pulse == e->pulse) {
+                        e->duration += IMON_UNIT;
+                } else {
+                        if (!max--)
+                                return -ENOBUFS;
+                        init_ir_raw_event_duration(++e, pulse, IMON_UNIT);
+                }
+
+                pulse = !(scancode & BIT(i));
+
+                if (pulse == e->pulse) {
+                        e->duration += IMON_UNIT;
+                } else {
+                        if (!max--)
+                                return -ENOBUFS;
+                        init_ir_raw_event_duration(++e, pulse, IMON_UNIT);
+                }
+        }
+
+        if (e->pulse)
+                e++;
+
+        return e - events;
+}
+
+static struct ir_raw_handler imon_handler = {
+        .protocols      = RC_PROTO_BIT_IMON,
+        .decode         = ir_imon_decode,
+        .encode         = ir_imon_encode,
+        .carrier        = 38000,
+};
+
+static int __init ir_imon_decode_init(void)
+{
+        ir_raw_handler_register(&imon_handler);
+
+        pr_info("IR iMON protocol handler initialized\n");
+        return 0;
+}
+
+static void __exit ir_imon_decode_exit(void)
+{
+        ir_raw_handler_unregister(&imon_handler);
+}
+
+module_init(ir_imon_decode_init);
+module_exit(ir_imon_decode_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Sean Young <sean@mess.org>");
+MODULE_DESCRIPTION("iMON IR protocol decoder");
diff --git a/drivers/media/rc/keymaps/rc-imon-pad.c b/drivers/media/rc/keymaps/rc-imon-pad.c
index a7296ffbf218..8501cf0a3253 100644
--- a/drivers/media/rc/keymaps/rc-imon-pad.c
+++ b/drivers/media/rc/keymaps/rc-imon-pad.c
@@ -134,8 +134,7 @@ static struct rc_map_list imon_pad_map = {
         .map = {
                 .scan     = imon_pad,
                 .size     = ARRAY_SIZE(imon_pad),
-                /* actual protocol details unknown, hardware decoder */
-                .rc_proto = RC_PROTO_OTHER,
+                .rc_proto = RC_PROTO_IMON,
                 .name     = RC_MAP_IMON_PAD,
         }
 };
diff --git a/drivers/media/rc/rc-core-priv.h b/drivers/media/rc/rc-core-priv.h
index 5e80b4273e2d..e0e6a17460f6 100644
--- a/drivers/media/rc/rc-core-priv.h
+++ b/drivers/media/rc/rc-core-priv.h
@@ -118,6 +118,12 @@ struct ir_raw_event_ctrl {
                 unsigned count;
                 u32 durations[16];
         } xmp;
+        struct imon_dec {
+                int state;
+                int count;
+                int last_chk;
+                unsigned int bits;
+        } imon;
 };
 
 /* macros for IR decoders */
diff --git a/drivers/media/rc/rc-main.c b/drivers/media/rc/rc-main.c
index 8621761a680f..b67be33bd62f 100644
--- a/drivers/media/rc/rc-main.c
+++ b/drivers/media/rc/rc-main.c
@@ -68,6 +68,8 @@ static const struct {
                 .scancode_bits = 0x1fff, .repeat_period = 250 },
         [RC_PROTO_XMP] = { .name = "xmp", .repeat_period = 250 },
         [RC_PROTO_CEC] = { .name = "cec", .repeat_period = 550 },
+        [RC_PROTO_IMON] = { .name = "imon",
+                .scancode_bits = 0x7fffffff, .repeat_period = 250 },
 };
 
 /* Used to keep track of known keymaps */
@@ -1004,6 +1006,7 @@ static const struct {
           RC_PROTO_BIT_MCIR2_MSE, "mce_kbd",    "ir-mce_kbd-decoder"    },
         { RC_PROTO_BIT_XMP,     "xmp",          "ir-xmp-decoder"        },
         { RC_PROTO_BIT_CEC,     "cec",          NULL                    },
+        { RC_PROTO_BIT_IMON,    "imon",         "ir-imon-decoder"       },
 };
 
 /**
diff --git a/include/media/rc-map.h b/include/media/rc-map.h
index 7fc84991bd12..bfa3017cecba 100644
--- a/include/media/rc-map.h
+++ b/include/media/rc-map.h
@@ -36,6 +36,7 @@
 #define RC_PROTO_BIT_SHARP              BIT_ULL(RC_PROTO_SHARP)
 #define RC_PROTO_BIT_XMP                BIT_ULL(RC_PROTO_XMP)
 #define RC_PROTO_BIT_CEC                BIT_ULL(RC_PROTO_CEC)
+#define RC_PROTO_BIT_IMON               BIT_ULL(RC_PROTO_IMON)
 
 #define RC_PROTO_BIT_ALL \
                         (RC_PROTO_BIT_UNKNOWN | RC_PROTO_BIT_OTHER | \
@@ -49,7 +50,8 @@
                          RC_PROTO_BIT_RC6_0 | RC_PROTO_BIT_RC6_6A_20 | \
                          RC_PROTO_BIT_RC6_6A_24 | RC_PROTO_BIT_RC6_6A_32 | \
                          RC_PROTO_BIT_RC6_MCE | RC_PROTO_BIT_SHARP | \
-                         RC_PROTO_BIT_XMP | RC_PROTO_BIT_CEC)
+                         RC_PROTO_BIT_XMP | RC_PROTO_BIT_CEC | \
+                         RC_PROTO_BIT_IMON)
 /* All rc protocols for which we have decoders */
 #define RC_PROTO_BIT_ALL_IR_DECODER \
                         (RC_PROTO_BIT_RC5 | RC_PROTO_BIT_RC5X_20 | \
@@ -62,7 +64,7 @@
                          RC_PROTO_BIT_RC6_0 | RC_PROTO_BIT_RC6_6A_20 | \
                          RC_PROTO_BIT_RC6_6A_24 |  RC_PROTO_BIT_RC6_6A_32 | \
                          RC_PROTO_BIT_RC6_MCE | RC_PROTO_BIT_SHARP | \
-                         RC_PROTO_BIT_XMP)
+                         RC_PROTO_BIT_XMP | RC_PROTO_BIT_IMON)
 
 #define RC_PROTO_BIT_ALL_IR_ENCODER \
                         (RC_PROTO_BIT_RC5 | RC_PROTO_BIT_RC5X_20 | \
@@ -75,7 +77,7 @@
                          RC_PROTO_BIT_RC6_0 | RC_PROTO_BIT_RC6_6A_20 | \
                          RC_PROTO_BIT_RC6_6A_24 | \
                          RC_PROTO_BIT_RC6_6A_32 | RC_PROTO_BIT_RC6_MCE | \
-                         RC_PROTO_BIT_SHARP)
+                         RC_PROTO_BIT_SHARP | RC_PROTO_BIT_IMON)
 
 #define RC_SCANCODE_UNKNOWN(x)                  (x)
 #define RC_SCANCODE_OTHER(x)                    (x)
diff --git a/include/uapi/linux/lirc.h b/include/uapi/linux/lirc.h
index 4fe580d36e41..948d9a491083 100644
--- a/include/uapi/linux/lirc.h
+++ b/include/uapi/linux/lirc.h
@@ -186,6 +186,7 @@ struct lirc_scancode {
  * @RC_PROTO_SHARP: Sharp protocol
  * @RC_PROTO_XMP: XMP protocol
  * @RC_PROTO_CEC: CEC protocol
+ * @RC_PROTO_IMON: iMon Pad protocol
  */
 enum rc_proto {
         RC_PROTO_UNKNOWN        = 0,
@@ -211,6 +212,7 @@ enum rc_proto {
         RC_PROTO_SHARP          = 20,
         RC_PROTO_XMP            = 21,
         RC_PROTO_CEC            = 22,
+        RC_PROTO_IMON           = 23,
 };
 
 #endif