From: Martin Povišer povik+lin@cutebit.org
[ Upstream commit 568aa6dd641f63166bb60d769e256789b3ac42d4 ]
There's a previously unknown part of the controller interface: We have to assign SRAM carveouts to channels to store their in-flight samples in. So, obtain the size of the SRAM from a read-only register and divide it into 2K blocks for allocation to channels. The FIFO depths we configure will always fit into 2K.
(This fixes audio artifacts during simultaneous playback/capture on multiple channels -- which looking back is fully accounted for by having had the caches in the DMA controller overlap in memory.)
Fixes: b127315d9a78 ("dmaengine: apple-admac: Add Apple ADMAC driver") Signed-off-by: Martin Povišer povik+lin@cutebit.org Link: https://lore.kernel.org/r/20221019132324.8585-2-povik+lin@cutebit.org Signed-off-by: Vinod Koul vkoul@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/dma/apple-admac.c | 102 +++++++++++++++++++++++++++++++++++++- 1 file changed, 101 insertions(+), 1 deletion(-)
diff --git a/drivers/dma/apple-admac.c b/drivers/dma/apple-admac.c index d69ed9c93648..e3334762be85 100644 --- a/drivers/dma/apple-admac.c +++ b/drivers/dma/apple-admac.c @@ -20,6 +20,12 @@ #define NCHANNELS_MAX 64 #define IRQ_NOUTPUTS 4
+/* + * For allocation purposes we split the cache + * memory into blocks of fixed size (given in bytes). + */ +#define SRAM_BLOCK 2048 + #define RING_WRITE_SLOT GENMASK(1, 0) #define RING_READ_SLOT GENMASK(5, 4) #define RING_FULL BIT(9) @@ -35,6 +41,9 @@ #define REG_TX_STOP 0x0004 #define REG_RX_START 0x0008 #define REG_RX_STOP 0x000c +#define REG_IMPRINT 0x0090 +#define REG_TX_SRAM_SIZE 0x0094 +#define REG_RX_SRAM_SIZE 0x0098
#define REG_CHAN_CTL(ch) (0x8000 + (ch) * 0x200) #define REG_CHAN_CTL_RST_RINGS BIT(0) @@ -52,7 +61,9 @@ #define BUS_WIDTH_FRAME_2_WORDS 0x10 #define BUS_WIDTH_FRAME_4_WORDS 0x20
-#define CHAN_BUFSIZE 0x8000 +#define REG_CHAN_SRAM_CARVEOUT(ch) (0x8050 + (ch) * 0x200) +#define CHAN_SRAM_CARVEOUT_SIZE GENMASK(31, 16) +#define CHAN_SRAM_CARVEOUT_BASE GENMASK(15, 0)
#define REG_CHAN_FIFOCTL(ch) (0x8054 + (ch) * 0x200) #define CHAN_FIFOCTL_LIMIT GENMASK(31, 16) @@ -75,6 +86,8 @@ struct admac_chan { struct dma_chan chan; struct tasklet_struct tasklet;
+ u32 carveout; + spinlock_t lock; struct admac_tx *current_tx; int nperiod_acks; @@ -91,11 +104,23 @@ struct admac_chan { struct list_head to_free; };
+struct admac_sram { + u32 size; + /* + * SRAM_CARVEOUT has 16-bit fields, so the SRAM cannot be larger than + * 64K and a 32-bit bitfield over 2K blocks covers it. + */ + u32 allocated; +}; + struct admac_data { struct dma_device dma; struct device *dev; __iomem void *base;
+ struct mutex cache_alloc_lock; + struct admac_sram txcache, rxcache; + int irq; int irq_index; int nchannels; @@ -116,6 +141,60 @@ struct admac_tx { struct list_head node; };
+static int admac_alloc_sram_carveout(struct admac_data *ad, + enum dma_transfer_direction dir, + u32 *out) +{ + struct admac_sram *sram; + int i, ret = 0, nblocks; + + if (dir == DMA_MEM_TO_DEV) + sram = &ad->txcache; + else + sram = &ad->rxcache; + + mutex_lock(&ad->cache_alloc_lock); + + nblocks = sram->size / SRAM_BLOCK; + for (i = 0; i < nblocks; i++) + if (!(sram->allocated & BIT(i))) + break; + + if (i < nblocks) { + *out = FIELD_PREP(CHAN_SRAM_CARVEOUT_BASE, i * SRAM_BLOCK) | + FIELD_PREP(CHAN_SRAM_CARVEOUT_SIZE, SRAM_BLOCK); + sram->allocated |= BIT(i); + } else { + ret = -EBUSY; + } + + mutex_unlock(&ad->cache_alloc_lock); + + return ret; +} + +static void admac_free_sram_carveout(struct admac_data *ad, + enum dma_transfer_direction dir, + u32 carveout) +{ + struct admac_sram *sram; + u32 base = FIELD_GET(CHAN_SRAM_CARVEOUT_BASE, carveout); + int i; + + if (dir == DMA_MEM_TO_DEV) + sram = &ad->txcache; + else + sram = &ad->rxcache; + + if (WARN_ON(base >= sram->size)) + return; + + mutex_lock(&ad->cache_alloc_lock); + i = base / SRAM_BLOCK; + sram->allocated &= ~BIT(i); + mutex_unlock(&ad->cache_alloc_lock); +} + static void admac_modify(struct admac_data *ad, int reg, u32 mask, u32 val) { void __iomem *addr = ad->base + reg; @@ -464,15 +543,28 @@ static void admac_synchronize(struct dma_chan *chan) static int admac_alloc_chan_resources(struct dma_chan *chan) { struct admac_chan *adchan = to_admac_chan(chan); + struct admac_data *ad = adchan->host; + int ret;
dma_cookie_init(&adchan->chan); + ret = admac_alloc_sram_carveout(ad, admac_chan_direction(adchan->no), + &adchan->carveout); + if (ret < 0) + return ret; + + writel_relaxed(adchan->carveout, + ad->base + REG_CHAN_SRAM_CARVEOUT(adchan->no)); return 0; }
static void admac_free_chan_resources(struct dma_chan *chan) { + struct admac_chan *adchan = to_admac_chan(chan); + admac_terminate_all(chan); admac_synchronize(chan); + admac_free_sram_carveout(adchan->host, admac_chan_direction(adchan->no), + adchan->carveout); }
static struct dma_chan *admac_dma_of_xlate(struct of_phandle_args *dma_spec, @@ -710,6 +802,7 @@ static int admac_probe(struct platform_device *pdev) platform_set_drvdata(pdev, ad); ad->dev = &pdev->dev; ad->nchannels = nchannels; + mutex_init(&ad->cache_alloc_lock);
/* * The controller has 4 IRQ outputs. Try them all until @@ -788,6 +881,13 @@ static int admac_probe(struct platform_device *pdev) goto free_irq; }
+ ad->txcache.size = readl_relaxed(ad->base + REG_TX_SRAM_SIZE); + ad->rxcache.size = readl_relaxed(ad->base + REG_RX_SRAM_SIZE); + + dev_info(&pdev->dev, "Audio DMA Controller\n"); + dev_info(&pdev->dev, "imprint %x TX cache %u RX cache %u\n", + readl_relaxed(ad->base + REG_IMPRINT), ad->txcache.size, ad->rxcache.size); + return 0;
free_irq: