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372 lines
8.8 KiB
372 lines
8.8 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Sound driver for Nintendo 64. |
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* |
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* Copyright 2021 Lauri Kasanen |
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*/ |
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#include <linux/dma-mapping.h> |
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#include <linux/init.h> |
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#include <linux/interrupt.h> |
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#include <linux/io.h> |
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#include <linux/log2.h> |
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#include <linux/module.h> |
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#include <linux/platform_device.h> |
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#include <linux/spinlock.h> |
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#include <sound/control.h> |
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#include <sound/core.h> |
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#include <sound/initval.h> |
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#include <sound/pcm.h> |
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#include <sound/pcm_params.h> |
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MODULE_AUTHOR("Lauri Kasanen <[email protected]>"); |
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MODULE_DESCRIPTION("N64 Audio"); |
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MODULE_LICENSE("GPL"); |
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#define AI_NTSC_DACRATE 48681812 |
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#define AI_STATUS_BUSY (1 << 30) |
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#define AI_STATUS_FULL (1 << 31) |
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#define AI_ADDR_REG 0 |
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#define AI_LEN_REG 1 |
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#define AI_CONTROL_REG 2 |
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#define AI_STATUS_REG 3 |
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#define AI_RATE_REG 4 |
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#define AI_BITCLOCK_REG 5 |
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#define MI_INTR_REG 2 |
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#define MI_MASK_REG 3 |
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#define MI_INTR_AI 0x04 |
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#define MI_MASK_CLR_AI 0x0010 |
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#define MI_MASK_SET_AI 0x0020 |
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struct n64audio { |
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u32 __iomem *ai_reg_base; |
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u32 __iomem *mi_reg_base; |
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void *ring_base; |
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dma_addr_t ring_base_dma; |
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struct snd_card *card; |
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struct { |
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struct snd_pcm_substream *substream; |
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int pos, nextpos; |
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u32 writesize; |
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u32 bufsize; |
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spinlock_t lock; |
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} chan; |
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}; |
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static void n64audio_write_reg(struct n64audio *priv, const u8 reg, const u32 value) |
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{ |
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writel(value, priv->ai_reg_base + reg); |
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} |
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static void n64mi_write_reg(struct n64audio *priv, const u8 reg, const u32 value) |
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{ |
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writel(value, priv->mi_reg_base + reg); |
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} |
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static u32 n64mi_read_reg(struct n64audio *priv, const u8 reg) |
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{ |
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return readl(priv->mi_reg_base + reg); |
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} |
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static void n64audio_push(struct n64audio *priv) |
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{ |
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struct snd_pcm_runtime *runtime = priv->chan.substream->runtime; |
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unsigned long flags; |
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u32 count; |
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spin_lock_irqsave(&priv->chan.lock, flags); |
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count = priv->chan.writesize; |
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memcpy(priv->ring_base + priv->chan.nextpos, |
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runtime->dma_area + priv->chan.nextpos, count); |
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/* |
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* The hw registers are double-buffered, and the IRQ fires essentially |
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* one period behind. The core only allows one period's distance, so we |
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* keep a private DMA buffer to afford two. |
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*/ |
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n64audio_write_reg(priv, AI_ADDR_REG, priv->ring_base_dma + priv->chan.nextpos); |
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barrier(); |
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n64audio_write_reg(priv, AI_LEN_REG, count); |
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priv->chan.nextpos += count; |
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priv->chan.nextpos %= priv->chan.bufsize; |
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runtime->delay = runtime->period_size; |
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spin_unlock_irqrestore(&priv->chan.lock, flags); |
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} |
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static irqreturn_t n64audio_isr(int irq, void *dev_id) |
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{ |
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struct n64audio *priv = dev_id; |
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const u32 intrs = n64mi_read_reg(priv, MI_INTR_REG); |
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unsigned long flags; |
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// Check it's ours |
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if (!(intrs & MI_INTR_AI)) |
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return IRQ_NONE; |
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n64audio_write_reg(priv, AI_STATUS_REG, 1); |
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if (priv->chan.substream && snd_pcm_running(priv->chan.substream)) { |
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spin_lock_irqsave(&priv->chan.lock, flags); |
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priv->chan.pos = priv->chan.nextpos; |
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spin_unlock_irqrestore(&priv->chan.lock, flags); |
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snd_pcm_period_elapsed(priv->chan.substream); |
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if (priv->chan.substream && snd_pcm_running(priv->chan.substream)) |
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n64audio_push(priv); |
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} |
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return IRQ_HANDLED; |
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} |
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static const struct snd_pcm_hardware n64audio_pcm_hw = { |
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.info = (SNDRV_PCM_INFO_MMAP | |
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SNDRV_PCM_INFO_MMAP_VALID | |
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SNDRV_PCM_INFO_INTERLEAVED | |
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SNDRV_PCM_INFO_BLOCK_TRANSFER), |
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.formats = SNDRV_PCM_FMTBIT_S16_BE, |
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.rates = SNDRV_PCM_RATE_8000_48000, |
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.rate_min = 8000, |
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.rate_max = 48000, |
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.channels_min = 2, |
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.channels_max = 2, |
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.buffer_bytes_max = 32768, |
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.period_bytes_min = 1024, |
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.period_bytes_max = 32768, |
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.periods_min = 3, |
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// 3 periods lets the double-buffering hw read one buffer behind safely |
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.periods_max = 128, |
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}; |
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static int hw_rule_period_size(struct snd_pcm_hw_params *params, |
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struct snd_pcm_hw_rule *rule) |
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{ |
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struct snd_interval *c = hw_param_interval(params, |
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SNDRV_PCM_HW_PARAM_PERIOD_SIZE); |
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int changed = 0; |
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/* |
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* The DMA unit has errata on (start + len) & 0x3fff == 0x2000. |
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* This constraint makes sure that the period size is not a power of two, |
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* which combined with dma_alloc_coherent aligning the buffer to the largest |
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* PoT <= size guarantees it won't be hit. |
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*/ |
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if (is_power_of_2(c->min)) { |
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c->min += 2; |
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changed = 1; |
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} |
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if (is_power_of_2(c->max)) { |
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c->max -= 2; |
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changed = 1; |
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} |
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if (snd_interval_checkempty(c)) { |
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c->empty = 1; |
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return -EINVAL; |
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} |
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return changed; |
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} |
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static int n64audio_pcm_open(struct snd_pcm_substream *substream) |
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{ |
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struct snd_pcm_runtime *runtime = substream->runtime; |
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int err; |
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runtime->hw = n64audio_pcm_hw; |
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err = snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS); |
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if (err < 0) |
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return err; |
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err = snd_pcm_hw_constraint_step(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, 2); |
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if (err < 0) |
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return err; |
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err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, |
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hw_rule_period_size, NULL, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, -1); |
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if (err < 0) |
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return err; |
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return 0; |
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} |
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static int n64audio_pcm_prepare(struct snd_pcm_substream *substream) |
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{ |
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struct snd_pcm_runtime *runtime = substream->runtime; |
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struct n64audio *priv = substream->pcm->private_data; |
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u32 rate; |
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rate = ((2 * AI_NTSC_DACRATE / runtime->rate) + 1) / 2 - 1; |
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n64audio_write_reg(priv, AI_RATE_REG, rate); |
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rate /= 66; |
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if (rate > 16) |
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rate = 16; |
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n64audio_write_reg(priv, AI_BITCLOCK_REG, rate - 1); |
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spin_lock_irq(&priv->chan.lock); |
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/* Setup the pseudo-dma transfer pointers. */ |
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priv->chan.pos = 0; |
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priv->chan.nextpos = 0; |
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priv->chan.substream = substream; |
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priv->chan.writesize = snd_pcm_lib_period_bytes(substream); |
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priv->chan.bufsize = snd_pcm_lib_buffer_bytes(substream); |
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spin_unlock_irq(&priv->chan.lock); |
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return 0; |
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} |
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static int n64audio_pcm_trigger(struct snd_pcm_substream *substream, |
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int cmd) |
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{ |
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struct n64audio *priv = substream->pcm->private_data; |
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switch (cmd) { |
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case SNDRV_PCM_TRIGGER_START: |
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n64audio_push(substream->pcm->private_data); |
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n64audio_write_reg(priv, AI_CONTROL_REG, 1); |
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n64mi_write_reg(priv, MI_MASK_REG, MI_MASK_SET_AI); |
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break; |
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case SNDRV_PCM_TRIGGER_STOP: |
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n64audio_write_reg(priv, AI_CONTROL_REG, 0); |
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n64mi_write_reg(priv, MI_MASK_REG, MI_MASK_CLR_AI); |
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break; |
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default: |
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return -EINVAL; |
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} |
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return 0; |
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} |
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static snd_pcm_uframes_t n64audio_pcm_pointer(struct snd_pcm_substream *substream) |
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{ |
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struct n64audio *priv = substream->pcm->private_data; |
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return bytes_to_frames(substream->runtime, |
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priv->chan.pos); |
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} |
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static int n64audio_pcm_close(struct snd_pcm_substream *substream) |
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{ |
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struct n64audio *priv = substream->pcm->private_data; |
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priv->chan.substream = NULL; |
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return 0; |
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} |
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static const struct snd_pcm_ops n64audio_pcm_ops = { |
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.open = n64audio_pcm_open, |
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.prepare = n64audio_pcm_prepare, |
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.trigger = n64audio_pcm_trigger, |
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.pointer = n64audio_pcm_pointer, |
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.close = n64audio_pcm_close, |
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}; |
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/* |
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* The target device is embedded and RAM-constrained. We save RAM |
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* by initializing in __init code that gets dropped late in boot. |
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* For the same reason there is no module or unloading support. |
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*/ |
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static int __init n64audio_probe(struct platform_device *pdev) |
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{ |
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struct snd_card *card; |
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struct snd_pcm *pcm; |
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struct n64audio *priv; |
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struct resource *res; |
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int err; |
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err = snd_card_new(&pdev->dev, SNDRV_DEFAULT_IDX1, |
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SNDRV_DEFAULT_STR1, |
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THIS_MODULE, sizeof(*priv), &card); |
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if (err < 0) |
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return err; |
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priv = card->private_data; |
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spin_lock_init(&priv->chan.lock); |
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priv->card = card; |
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priv->ring_base = dma_alloc_coherent(card->dev, 32 * 1024, &priv->ring_base_dma, |
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GFP_DMA|GFP_KERNEL); |
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if (!priv->ring_base) { |
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err = -ENOMEM; |
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goto fail_card; |
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} |
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priv->mi_reg_base = devm_platform_ioremap_resource(pdev, 0); |
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if (IS_ERR(priv->mi_reg_base)) { |
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err = PTR_ERR(priv->mi_reg_base); |
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goto fail_dma_alloc; |
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} |
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priv->ai_reg_base = devm_platform_ioremap_resource(pdev, 1); |
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if (IS_ERR(priv->ai_reg_base)) { |
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err = PTR_ERR(priv->ai_reg_base); |
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goto fail_dma_alloc; |
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} |
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err = snd_pcm_new(card, "N64 Audio", 0, 1, 0, &pcm); |
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if (err < 0) |
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goto fail_dma_alloc; |
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pcm->private_data = priv; |
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strcpy(pcm->name, "N64 Audio"); |
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snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &n64audio_pcm_ops); |
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snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_VMALLOC, card->dev, 0, 0); |
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strcpy(card->driver, "N64 Audio"); |
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strcpy(card->shortname, "N64 Audio"); |
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strcpy(card->longname, "N64 Audio"); |
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res = platform_get_resource(pdev, IORESOURCE_IRQ, 0); |
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if (devm_request_irq(&pdev->dev, res->start, n64audio_isr, |
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IRQF_SHARED, "N64 Audio", priv)) { |
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err = -EBUSY; |
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goto fail_dma_alloc; |
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} |
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err = snd_card_register(card); |
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if (err < 0) |
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goto fail_dma_alloc; |
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return 0; |
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fail_dma_alloc: |
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dma_free_coherent(card->dev, 32 * 1024, priv->ring_base, priv->ring_base_dma); |
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fail_card: |
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snd_card_free(card); |
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return err; |
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} |
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static struct platform_driver n64audio_driver = { |
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.driver = { |
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.name = "n64audio", |
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}, |
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}; |
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static int __init n64audio_init(void) |
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{ |
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return platform_driver_probe(&n64audio_driver, n64audio_probe); |
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} |
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module_init(n64audio_init);
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