From 9b09df51b8c2b4615376e5ada3e2eb7eeed3cf5d Mon Sep 17 00:00:00 2001 From: Mauro Carvalho Chehab Date: Tue, 6 Apr 2010 02:29:42 -0300 Subject: [PATCH] V4L/DVB: ir-rc5-decoder: fix state machine Reimplement the RC-5 decoder state machine. Code is now clear, and works properly. It is also simpler than the previous implementations. Signed-off-by: Mauro Carvalho Chehab --- drivers/media/IR/ir-rc5-decoder.c | 161 ++++++++++-------------------- 1 file changed, 52 insertions(+), 109 deletions(-) diff --git a/drivers/media/IR/ir-rc5-decoder.c b/drivers/media/IR/ir-rc5-decoder.c index 4fb3ce410e24..a62277b625a8 100644 --- a/drivers/media/IR/ir-rc5-decoder.c +++ b/drivers/media/IR/ir-rc5-decoder.c @@ -15,19 +15,17 @@ /* * This code only handles 14 bits RC-5 protocols. There are other variants * that use a different number of bits. This is currently unsupported + * It considers a carrier of 36 kHz, with a total of 14 bits, where + * the first two bits are start bits, and a third one is a filing bit */ #include -#define RC5_NBITS 14 -#define RC5_HALFBIT 888888 /* ns */ -#define RC5_BIT (RC5_HALFBIT * 2) -#define RC5_DURATION (RC5_BIT * RC5_NBITS) - -#define is_rc5_halfbit(nsec) ((ev->delta.tv_nsec >= RC5_HALFBIT / 2) && \ - (ev->delta.tv_nsec < RC5_HALFBIT + RC5_HALFBIT / 2)) +static unsigned int ir_rc5_remote_gap = 888888; -#define n_half(nsec) ((ev->delta.tv_nsec + RC5_HALFBIT / 2) / RC5_HALFBIT) +#define RC5_NBITS 14 +#define RC5_BIT (ir_rc5_remote_gap * 2) +#define RC5_DURATION (ir_rc5_remote_gap * RC5_NBITS) /* Used to register rc5_decoder clients */ static LIST_HEAD(decoder_list); @@ -35,19 +33,8 @@ static spinlock_t decoder_lock; enum rc5_state { STATE_INACTIVE, - STATE_START2_SPACE, - STATE_START2_MARK, STATE_MARKSPACE, - STATE_TRAILER_MARK, -}; - -static char *st_name[] = { - "Inactive", - "start2 sapce", - "start2 mark", - "mark", - "space", - "trailer" + STATE_TRAILER, }; struct rc5_code { @@ -63,8 +50,7 @@ struct decoder_data { /* State machine control */ enum rc5_state state; struct rc5_code rc5_code; - unsigned n_half; - unsigned count; + unsigned code, elapsed, last_bit, last_code; }; @@ -147,7 +133,7 @@ static int ir_rc5_decode(struct input_dev *input_dev, { struct decoder_data *data; struct ir_input_dev *ir_dev = input_get_drvdata(input_dev); - int bit, last_bit, n_half; + int is_pulse, scancode, delta, toggle; data = get_decoder_data(ir_dev); if (!data) @@ -156,122 +142,79 @@ static int ir_rc5_decode(struct input_dev *input_dev, if (!data->enabled) return 0; - /* Except for the initial event, what matters is the previous bit */ - bit = (ev->type & IR_PULSE) ? 1 : 0; - - last_bit = !bit; + delta = DIV_ROUND_CLOSEST(ev->delta.tv_nsec, ir_rc5_remote_gap); - /* Discards spurious space last_bits when inactive */ + /* The duration time refers to the last bit time */ + is_pulse = (ev->type & IR_PULSE) ? 1 : 0; /* Very long delays are considered as start events */ - if (ev->delta.tv_nsec > RC5_DURATION + RC5_HALFBIT / 2) - data->state = STATE_INACTIVE; - - if (ev->type & IR_START_EVENT) + if (delta > RC5_DURATION || (ev->type & IR_START_EVENT)) data->state = STATE_INACTIVE; switch (data->state) { case STATE_INACTIVE: -IR_dprintk(1, "currently inative. Received bit (%s) @%luus\n", - last_bit ? "pulse" : "space", - (ev->delta.tv_nsec + 500) / 1000); + IR_dprintk(2, "currently inative. Start bit (%s) @%uus\n", + is_pulse ? "pulse" : "space", + (unsigned)(ev->delta.tv_nsec + 500) / 1000); /* Discards the initial start space */ - if (bit) - return 0; - data->count = 0; - data->n_half = 0; - memset (&data->rc5_code, 0, sizeof(data->rc5_code)); - - data->state = STATE_START2_SPACE; - return 0; - case STATE_START2_SPACE: - if (last_bit) - goto err; - if (!is_rc5_halfbit(ev->delta.tv_nsec)) - goto err; - data->state = STATE_START2_MARK; - return 0; - case STATE_START2_MARK: - if (!last_bit) + if (!is_pulse) goto err; - - if (!is_rc5_halfbit(ev->delta.tv_nsec)) - goto err; - + data->code = 1; + data->last_bit = 1; + data->elapsed = 0; + memset(&data->rc5_code, 0, sizeof(data->rc5_code)); data->state = STATE_MARKSPACE; return 0; case STATE_MARKSPACE: - n_half = n_half(ev->delta.tv_nsec); - if (n_half < 1 || n_half > 3) { - IR_dprintk(1, "Decode failed at %d-th bit (%s) @%luus\n", - data->count, - last_bit ? "pulse" : "space", - (ev->delta.tv_nsec + 500) / 1000); -printk("%d halves\n", n_half); - goto err2; - } - data->n_half += n_half; + if (delta != 1) + data->last_bit = data->last_bit ? 0 : 1; - if (!last_bit) - return 0; + data->elapsed += delta; - /* Got one complete mark/space cycle */ + if ((data->elapsed % 2) == 1) + return 0; - bit = ((data->count + 1) * 2)/ data->n_half; + data->code <<= 1; + data->code |= data->last_bit; -printk("%d halves, %d bits\n", n_half, bit); + /* Fill the 2 unused bits at the command with 0 */ + if (data->elapsed / 2 == 6) + data->code <<= 2; -#if 1 /* SANITY check - while testing the decoder */ - if (bit > 1) { - IR_dprintk(1, "Decoder HAS failed at %d-th bit (%s) @%luus\n", - data->count, - last_bit ? "pulse" : "space", - (ev->delta.tv_nsec + 500) / 1000); + if (data->elapsed >= (RC5_NBITS - 1) * 2) { + scancode = data->code; - goto err2; - } -#endif - /* Ok, we've got a valid bit. proccess it */ - if (bit) { - int shift = data->count; - - /* - * RC-5 transmit bytes on this temporal order: - * address | not address | command | not command - */ - if (shift < 8) { - data->rc5_code.address |= 1 << shift; - } else { - data->rc5_code.command |= 1 << (shift - 8); + /* Check for the start bits */ + if ((scancode & 0xc000) != 0xc000) { + IR_dprintk(1, "Code 0x%04x doesn't have two start bits. It is not RC-5\n", scancode); + goto err; } - } - IR_dprintk(1, "RC-5: bit #%d: %d (%d)\n", - data->count, bit, data->n_half); - if (++data->count >= RC5_NBITS) { - u32 scancode; - scancode = data->rc5_code.address << 8 | - data->rc5_code.command; - IR_dprintk(1, "RC-5 scancode 0x%04x\n", scancode); - ir_keydown(input_dev, scancode, 0); + toggle = (scancode & 0x2000) ? 1 : 0; + + if (scancode == data->last_code) { + IR_dprintk(1, "RC-5 repeat\n"); + ir_repeat(input_dev); + } else { + data->last_code = scancode; + scancode &= 0x1fff; + IR_dprintk(1, "RC-5 scancode 0x%04x\n", scancode); - data->state = STATE_TRAILER_MARK; + ir_keydown(input_dev, scancode, 0); + } + data->state = STATE_TRAILER; } return 0; - case STATE_TRAILER_MARK: - if (!last_bit) - goto err; + case STATE_TRAILER: data->state = STATE_INACTIVE; return 0; } err: - IR_dprintk(1, "RC-5 decoded failed at state %s (%s) @ %luus\n", - st_name[data->state], - bit ? "pulse" : "space", + IR_dprintk(1, "RC-5 decoded failed at %s @ %luus\n", + is_pulse ? "pulse" : "space", (ev->delta.tv_nsec + 500) / 1000); -err2: data->state = STATE_INACTIVE; return -EINVAL; } -- 2.30.2