aboutsummaryrefslogtreecommitdiffstats
path: root/utils/keytable/bpf_protocols/pulse_length.c
diff options
context:
space:
mode:
authorSean Young <sean@mess.org>2018-05-24 13:30:08 +0100
committerSean Young <sean@mess.org>2018-08-13 10:15:52 +0100
commit91b37c0d9cb71fc2d5f78cc96aa2ef9f3bba145b (patch)
treeaf2d2a94098fe923d4eaa26c4aa2e0d2d6b7c3fa /utils/keytable/bpf_protocols/pulse_length.c
parentd6025b0e8c7f57b0f9390f987acc5eed57360d80 (diff)
keytable: add bpf protocols
Add a few BPF protocols and infrastructure for building them. Signed-off-by: Sean Young <sean@mess.org>
Diffstat (limited to 'utils/keytable/bpf_protocols/pulse_length.c')
-rw-r--r--utils/keytable/bpf_protocols/pulse_length.c152
1 files changed, 152 insertions, 0 deletions
diff --git a/utils/keytable/bpf_protocols/pulse_length.c b/utils/keytable/bpf_protocols/pulse_length.c
new file mode 100644
index 00000000..e33f0899
--- /dev/null
+++ b/utils/keytable/bpf_protocols/pulse_length.c
@@ -0,0 +1,152 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// Copyright (C) 2018 Sean Young <sean@mess.org>
+
+#include <linux/lirc.h>
+#include <linux/bpf.h>
+
+#include "bpf_helpers.h"
+
+enum state {
+ STATE_INACTIVE,
+ STATE_HEADER_SPACE,
+ STATE_REPEAT_SPACE,
+ STATE_BITS_SPACE,
+ STATE_BITS_PULSE,
+ STATE_TRAILER,
+};
+
+struct decoder_state {
+ unsigned long bits;
+ enum state state;
+ unsigned int count;
+};
+
+struct bpf_map_def SEC("maps") decoder_state_map = {
+ .type = BPF_MAP_TYPE_ARRAY,
+ .key_size = sizeof(unsigned int),
+ .value_size = sizeof(struct decoder_state),
+ .max_entries = 1,
+};
+
+// These values can be overridden in the rc_keymap toml
+//
+// We abuse elf relocations. We cast the address of these variables to
+// an int, so that the compiler emits a mov immediate for the address
+// but uses it as an int. The bpf loader replaces the relocation with the
+// actual value (either overridden or taken from the data segment).
+int margin = 200;
+int header_pulse = 2125;
+int header_space = 1875;
+int repeat_pulse = 0;
+int repeat_space = 0;
+int bit_space = 625;
+int bit_0_pulse = 375;
+int bit_1_pulse = 1625;
+int trailer_pulse = 0;
+int bits = 4;
+int reverse = 0;
+int header_optional = 0;
+int rc_protocol = 67;
+
+#define BPF_PARAM(x) (int)(&(x))
+
+static inline int eq_margin(unsigned d1, unsigned d2)
+{
+ return ((d1 > (d2 - BPF_PARAM(margin))) && (d1 < (d2 + BPF_PARAM(margin))));
+}
+
+SEC("pulse_length")
+int bpf_decoder(unsigned int *sample)
+{
+ unsigned int key = 0;
+ struct decoder_state *s = bpf_map_lookup_elem(&decoder_state_map, &key);
+
+ if (!s)
+ return 0;
+
+ switch (*sample & LIRC_MODE2_MASK) {
+ case LIRC_MODE2_SPACE:
+ case LIRC_MODE2_PULSE:
+ case LIRC_MODE2_TIMEOUT:
+ break;
+ default:
+ // not a timing events
+ return 0;
+ }
+
+ int duration = LIRC_VALUE(*sample);
+ int pulse = LIRC_IS_PULSE(*sample);
+
+ switch (s->state) {
+ case STATE_HEADER_SPACE:
+ if (!pulse && eq_margin(BPF_PARAM(header_space), duration))
+ s->state = STATE_BITS_PULSE;
+ else
+ s->state = STATE_INACTIVE;
+ break;
+ case STATE_REPEAT_SPACE:
+ if (!pulse && eq_margin(BPF_PARAM(repeat_space), duration))
+ s->state = STATE_TRAILER;
+ else
+ s->state = STATE_INACTIVE;
+ break;
+ case STATE_INACTIVE:
+ if (pulse && eq_margin(BPF_PARAM(header_pulse), duration)) {
+ s->bits = 0;
+ s->state = STATE_HEADER_SPACE;
+ s->count = 0;
+ break;
+ }
+ if (pulse && BPF_PARAM(repeat_pulse) > 0 &&
+ eq_margin(BPF_PARAM(repeat_pulse), duration)) {
+ s->state = STATE_REPEAT_SPACE;
+ s->count = 0;
+ break;
+ }
+ if (!BPF_PARAM(header_optional))
+ break;
+ /* pass through */
+ case STATE_BITS_PULSE:
+ if (!pulse)
+ break;
+
+ unsigned long set_bit = 1;
+
+ if (BPF_PARAM(reverse))
+ set_bit <<= s->count;
+ else
+ s->bits <<= 1;
+
+ if (eq_margin(BPF_PARAM(bit_1_pulse), duration))
+ s->bits |= set_bit;
+ else if (!eq_margin(BPF_PARAM(bit_0_pulse), duration)) {
+ s->state = STATE_INACTIVE;
+ break;
+ }
+
+ s->count++;
+ if (s->count == BPF_PARAM(bits)) {
+ bpf_rc_keydown(sample, BPF_PARAM(rc_protocol), s->bits, 0);
+ s->state = STATE_INACTIVE;
+ } else {
+ s->state = STATE_BITS_SPACE;
+ }
+ break;
+ case STATE_BITS_SPACE:
+ if (!pulse && eq_margin(BPF_PARAM(bit_space), duration))
+ s->state = STATE_BITS_PULSE;
+ else
+ s->state = STATE_INACTIVE;
+ break;
+ case STATE_TRAILER:
+ if (pulse && eq_margin(BPF_PARAM(trailer_pulse), duration))
+ bpf_rc_repeat(sample);
+
+ s->state = STATE_INACTIVE;
+ }
+
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";

Privacy Policy