diff options
Diffstat (limited to 'sound/soc/bcm/bcm2835-i2s.c')
| -rw-r--r-- | sound/soc/bcm/bcm2835-i2s.c | 152 |
1 files changed, 99 insertions, 53 deletions
diff --git a/sound/soc/bcm/bcm2835-i2s.c b/sound/soc/bcm/bcm2835-i2s.c index 111b4ef7ce35..2e449d7173fc 100644 --- a/sound/soc/bcm/bcm2835-i2s.c +++ b/sound/soc/bcm/bcm2835-i2s.c @@ -344,6 +344,9 @@ static int bcm2835_i2s_hw_params(struct snd_pcm_substream *substream, unsigned int rx_mask, tx_mask; unsigned int rx_ch1_pos, rx_ch2_pos, tx_ch1_pos, tx_ch2_pos; unsigned int mode, format; + bool bit_clock_master = false; + bool frame_sync_master = false; + bool frame_start_falling_edge = false; uint32_t csreg; int ret = 0; @@ -387,16 +390,39 @@ static int bcm2835_i2s_hw_params(struct snd_pcm_substream *substream, if (data_length > slot_width) return -EINVAL; - /* Clock should only be set up here if CPU is clock master */ + /* Check if CPU is bit clock master */ switch (dev->fmt & SND_SOC_DAIFMT_MASTER_MASK) { case SND_SOC_DAIFMT_CBS_CFS: case SND_SOC_DAIFMT_CBS_CFM: - ret = clk_set_rate(dev->clk, bclk_rate); - if (ret) - return ret; + bit_clock_master = true; + break; + case SND_SOC_DAIFMT_CBM_CFS: + case SND_SOC_DAIFMT_CBM_CFM: + bit_clock_master = false; break; default: + return -EINVAL; + } + + /* Check if CPU is frame sync master */ + switch (dev->fmt & SND_SOC_DAIFMT_MASTER_MASK) { + case SND_SOC_DAIFMT_CBS_CFS: + case SND_SOC_DAIFMT_CBM_CFS: + frame_sync_master = true; + break; + case SND_SOC_DAIFMT_CBS_CFM: + case SND_SOC_DAIFMT_CBM_CFM: + frame_sync_master = false; break; + default: + return -EINVAL; + } + + /* Clock should only be set up here if CPU is clock master */ + if (bit_clock_master) { + ret = clk_set_rate(dev->clk, bclk_rate); + if (ret) + return ret; } /* Setup the frame format */ @@ -427,13 +453,41 @@ static int bcm2835_i2s_hw_params(struct snd_pcm_substream *substream, /* Setup frame sync signal for 50% duty cycle */ framesync_length = frame_length / 2; + frame_start_falling_edge = true; + break; + case SND_SOC_DAIFMT_LEFT_J: + if (slots & 1) + return -EINVAL; + + odd_slot_offset = slots >> 1; + data_delay = 0; + framesync_length = frame_length / 2; + frame_start_falling_edge = false; + break; + case SND_SOC_DAIFMT_RIGHT_J: + if (slots & 1) + return -EINVAL; + + /* Odd frame lengths aren't supported */ + if (frame_length & 1) + return -EINVAL; + + odd_slot_offset = slots >> 1; + data_delay = slot_width - data_length; + framesync_length = frame_length / 2; + frame_start_falling_edge = false; + break; + case SND_SOC_DAIFMT_DSP_A: + data_delay = 1; + framesync_length = 1; + frame_start_falling_edge = false; + break; + case SND_SOC_DAIFMT_DSP_B: + data_delay = 0; + framesync_length = 1; + frame_start_falling_edge = false; break; default: - /* - * TODO - * Others are possible but are not implemented at the moment. - */ - dev_err(dev->dev, "%s:bad format\n", __func__); return -EINVAL; } @@ -443,6 +497,15 @@ static int bcm2835_i2s_hw_params(struct snd_pcm_substream *substream, tx_mask, slot_width, data_delay, odd_slot_offset); /* + * Transmitting data immediately after frame start, eg + * in left-justified or DSP mode A, only works stable + * if bcm2835 is the frame clock master. + */ + if ((!rx_ch1_pos || !tx_ch1_pos) && !frame_sync_master) + dev_warn(dev->dev, + "Unstable slave config detected, L/R may be swapped"); + + /* * Set format for both streams. * We cannot set another frame length * (and therefore word length) anyway, @@ -472,62 +535,38 @@ static int bcm2835_i2s_hw_params(struct snd_pcm_substream *substream, mode |= BCM2835_I2S_FLEN(frame_length - 1); mode |= BCM2835_I2S_FSLEN(framesync_length); - /* Master or slave? */ - switch (dev->fmt & SND_SOC_DAIFMT_MASTER_MASK) { - case SND_SOC_DAIFMT_CBS_CFS: - /* CPU is master */ - break; - case SND_SOC_DAIFMT_CBM_CFS: - /* - * CODEC is bit clock master - * CPU is frame master - */ + /* CLKM selects bcm2835 clock slave mode */ + if (!bit_clock_master) mode |= BCM2835_I2S_CLKM; - break; - case SND_SOC_DAIFMT_CBS_CFM: - /* - * CODEC is frame master - * CPU is bit clock master - */ + + /* FSM selects bcm2835 frame sync slave mode */ + if (!frame_sync_master) mode |= BCM2835_I2S_FSM; + + /* CLKI selects normal clocking mode, sampling on rising edge */ + switch (dev->fmt & SND_SOC_DAIFMT_INV_MASK) { + case SND_SOC_DAIFMT_NB_NF: + case SND_SOC_DAIFMT_NB_IF: + mode |= BCM2835_I2S_CLKI; break; - case SND_SOC_DAIFMT_CBM_CFM: - /* CODEC is master */ - mode |= BCM2835_I2S_CLKM; - mode |= BCM2835_I2S_FSM; + case SND_SOC_DAIFMT_IB_NF: + case SND_SOC_DAIFMT_IB_IF: break; default: - dev_err(dev->dev, "%s:bad master\n", __func__); return -EINVAL; } - /* - * Invert clocks? - * - * The BCM approach seems to be inverted to the classical I2S approach. - */ + /* FSI selects frame start on falling edge */ switch (dev->fmt & SND_SOC_DAIFMT_INV_MASK) { case SND_SOC_DAIFMT_NB_NF: - /* None. Therefore, both for BCM */ - mode |= BCM2835_I2S_CLKI; - mode |= BCM2835_I2S_FSI; - break; - case SND_SOC_DAIFMT_IB_IF: - /* Both. Therefore, none for BCM */ + case SND_SOC_DAIFMT_IB_NF: + if (frame_start_falling_edge) + mode |= BCM2835_I2S_FSI; break; case SND_SOC_DAIFMT_NB_IF: - /* - * Invert only frame sync. Therefore, - * invert only bit clock for BCM - */ - mode |= BCM2835_I2S_CLKI; - break; - case SND_SOC_DAIFMT_IB_NF: - /* - * Invert only bit clock. Therefore, - * invert only frame sync for BCM - */ - mode |= BCM2835_I2S_FSI; + case SND_SOC_DAIFMT_IB_IF: + if (!frame_start_falling_edge) + mode |= BCM2835_I2S_FSI; break; default: return -EINVAL; @@ -563,6 +602,13 @@ static int bcm2835_i2s_hw_params(struct snd_pcm_substream *substream, dev_dbg(dev->dev, "sampling rate: %d bclk rate: %d\n", params_rate(params), bclk_rate); + dev_dbg(dev->dev, "CLKM: %d CLKI: %d FSM: %d FSI: %d frame start: %s edge\n", + !!(mode & BCM2835_I2S_CLKM), + !!(mode & BCM2835_I2S_CLKI), + !!(mode & BCM2835_I2S_FSM), + !!(mode & BCM2835_I2S_FSI), + (mode & BCM2835_I2S_FSI) ? "falling" : "rising"); + return ret; } |