[alsa-devel] [PATCH] asoc/multi-component: fsl: add support for 36-bit physical addresses
Timur Tabi
timur at freescale.com
Mon Aug 2 19:44:36 CEST 2010
Update the DMA driver used by the Freescale MPC8610 HPCD audio driver to
support 36-bit physical addresses, for both DMA buffers and the SSI registers.
The DMA driver calls snd_dma_alloc_pages() to allocate the DMA buffers for
playback and capture. This function is just a front-end for
dma_alloc_coherent(). Currently, dma_alloc_coherent() only allocates buffers
in low memory (it ignores GFP_HIGHMEM), so we never actually get a DMA buffer
with a real 36-bit physical address.
Signed-off-by: Timur Tabi <timur at freescale.com>
---
Liam, this patch should *not* be squashed into the rest of the changes for
multi-component.
sound/soc/fsl/fsl_dma.c | 77 +++++++++++++++++++++++++++++++----------------
1 files changed, 51 insertions(+), 26 deletions(-)
diff --git a/sound/soc/fsl/fsl_dma.c b/sound/soc/fsl/fsl_dma.c
index d09e194..4450f9d 100644
--- a/sound/soc/fsl/fsl_dma.c
+++ b/sound/soc/fsl/fsl_dma.c
@@ -175,13 +175,23 @@ static void fsl_dma_update_pointers(struct fsl_dma_private *dma_private)
struct fsl_dma_link_descriptor *link =
&dma_private->link[dma_private->current_link];
- /* Update our link descriptors to point to the next period */
- if (dma_private->substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
- link->source_addr =
- cpu_to_be32(dma_private->dma_buf_next);
- else
- link->dest_addr =
- cpu_to_be32(dma_private->dma_buf_next);
+ /* Update our link descriptors to point to the next period. On a 36-bit
+ * system, we also need to update the ESAD bits. We also set (keep) the
+ * snoop bits. See the comments in fsl_dma_hw_params() about snooping.
+ */
+ if (dma_private->substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+ link->source_addr = cpu_to_be32(dma_private->dma_buf_next);
+#ifdef CONFIG_PHYS_64BIT
+ link->source_attr = cpu_to_be32(CCSR_DMA_ATR_SNOOP |
+ upper_32_bits(dma_private->dma_buf_next));
+#endif
+ } else {
+ link->dest_addr = cpu_to_be32(dma_private->dma_buf_next);
+#ifdef CONFIG_PHYS_64BIT
+ link->dest_attr = cpu_to_be32(CCSR_DMA_ATR_SNOOP |
+ upper_32_bits(dma_private->dma_buf_next));
+#endif
+ }
/* Update our variables for next time */
dma_private->dma_buf_next += dma_private->period_size;
@@ -273,11 +283,19 @@ static irqreturn_t fsl_dma_isr(int irq, void *dev_id)
* This function is called when the codec driver calls snd_soc_new_pcms(),
* once for each .dai_link in the machine driver's snd_soc_card
* structure.
+ *
+ * snd_dma_alloc_pages() is just a front-end to dma_alloc_coherent(), which
+ * (currently) always allocates the DMA buffer in lowmem, even if GFP_HIGHMEM
+ * is specified. Therefore, any DMA buffers we allocate will always be in low
+ * memory, but we support for 36-bit physical addresses anyway.
+ *
+ * Regardless of where the memory is actually allocated, since the device can
+ * technically DMA to any 36-bit address, we do need to set the DMA mask to 36.
*/
static int fsl_dma_new(struct snd_card *card, struct snd_soc_dai *dai,
struct snd_pcm *pcm)
{
- static u64 fsl_dma_dmamask = DMA_BIT_MASK(32);
+ static u64 fsl_dma_dmamask = DMA_BIT_MASK(36);
int ret;
if (!card->dev->dma_mask)
@@ -609,12 +627,7 @@ static int fsl_dma_hw_params(struct snd_pcm_substream *substream,
link->count = cpu_to_be32(period_size);
- /* Even though the DMA controller supports 36-bit addressing,
- * for simplicity we allow only 32-bit addresses for the audio
- * buffer itself. This was enforced in fsl_dma_new() with the
- * DMA mask.
- *
- * The snoop bit tells the DMA controller whether it should tell
+ /* The snoop bit tells the DMA controller whether it should tell
* the ECM to snoop during a read or write to an address. For
* audio, we use DMA to transfer data between memory and an I/O
* device (the SSI's STX0 or SRX0 register). Snooping is only
@@ -629,20 +642,24 @@ static int fsl_dma_hw_params(struct snd_pcm_substream *substream,
* flush out the data for the previous period. So if you
* increased period_bytes_min to a large enough size, you might
* get more performance by not snooping, and you'll still be
- * okay.
+ * okay. You'll need to update fsl_dma_update_pointers() also.
*/
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
link->source_addr = cpu_to_be32(temp_addr);
- link->source_attr = cpu_to_be32(CCSR_DMA_ATR_SNOOP);
+ link->source_attr = cpu_to_be32(CCSR_DMA_ATR_SNOOP |
+ upper_32_bits(temp_addr));
link->dest_addr = cpu_to_be32(ssi_sxx_phys);
- link->dest_attr = cpu_to_be32(CCSR_DMA_ATR_NOSNOOP);
+ link->dest_attr = cpu_to_be32(CCSR_DMA_ATR_NOSNOOP |
+ upper_32_bits(ssi_sxx_phys));
} else {
link->source_addr = cpu_to_be32(ssi_sxx_phys);
- link->source_attr = cpu_to_be32(CCSR_DMA_ATR_NOSNOOP);
+ link->source_attr = cpu_to_be32(CCSR_DMA_ATR_NOSNOOP |
+ upper_32_bits(ssi_sxx_phys));
link->dest_addr = cpu_to_be32(temp_addr);
- link->dest_attr = cpu_to_be32(CCSR_DMA_ATR_SNOOP);
+ link->dest_attr = cpu_to_be32(CCSR_DMA_ATR_SNOOP |
+ upper_32_bits(temp_addr));
}
temp_addr += period_size;
@@ -673,10 +690,23 @@ static snd_pcm_uframes_t fsl_dma_pointer(struct snd_pcm_substream *substream)
dma_addr_t position;
snd_pcm_uframes_t frames;
- if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+ /* Obtain the current DMA pointer, but don't read the ESAD bits if we
+ * only have 32-bit DMA addresses. This function is typically called
+ * in interrupt context, so we need to optimize it.
+ */
+ if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
position = in_be32(&dma_channel->sar);
- else
+#ifdef CONFIG_PHYS_64BIT
+ position |= (u64)(in_be32(&dma_channel->satr) &
+ CCSR_DMA_ATR_ESAD_MASK) << 32;
+#endif
+ } else {
position = in_be32(&dma_channel->dar);
+#ifdef CONFIG_PHYS_64BIT
+ position |= (u64)(in_be32(&dma_channel->datr) &
+ CCSR_DMA_ATR_ESAD_MASK) << 32;
+#endif
+ }
/*
* When capture is started, the SSI immediately starts to fill its FIFO.
@@ -936,11 +966,6 @@ static void __exit fsl_soc_dma_exit(void)
of_unregister_platform_driver(&fsl_soc_dma_driver);
}
-/* We want the DMA driver to be initialized before the SSI driver, so that
- * when the SSI driver calls fsl_soc_dma_dai_from_node(), the DMA driver
- * will already have been probed. The easiest way to do that is to make the
- * __init function called via arch_initcall().
- */
module_init(fsl_soc_dma_init);
module_exit(fsl_soc_dma_exit);
--
1.7.0.1
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