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|
/*
* Freescale DMA ALSA SoC PCM driver
*
* Author: Timur Tabi <timur@freescale.com>
*
* Copyright 2007-2010 Freescale Semiconductor, Inc.
*
* This file is licensed under the terms of the GNU General Public License
* version 2. This program is licensed "as is" without any warranty of any
* kind, whether express or implied.
*
* This driver implements ASoC support for the Elo DMA controller, which is
* the DMA controller on Freescale 83xx, 85xx, and 86xx SOCs. In ALSA terms,
* the PCM driver is what handles the DMA buffer.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/gfp.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/of_platform.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/soc.h>
#include <asm/io.h>
#include "fsl_dma.h"
#include "fsl_ssi.h" /* For the offset of stx0 and srx0 */
/*
* The formats that the DMA controller supports, which is anything
* that is 8, 16, or 32 bits.
*/
#define FSLDMA_PCM_FORMATS (SNDRV_PCM_FMTBIT_S8 | \
SNDRV_PCM_FMTBIT_U8 | \
SNDRV_PCM_FMTBIT_S16_LE | \
SNDRV_PCM_FMTBIT_S16_BE | \
SNDRV_PCM_FMTBIT_U16_LE | \
SNDRV_PCM_FMTBIT_U16_BE | \
SNDRV_PCM_FMTBIT_S24_LE | \
SNDRV_PCM_FMTBIT_S24_BE | \
SNDRV_PCM_FMTBIT_U24_LE | \
SNDRV_PCM_FMTBIT_U24_BE | \
SNDRV_PCM_FMTBIT_S32_LE | \
SNDRV_PCM_FMTBIT_S32_BE | \
SNDRV_PCM_FMTBIT_U32_LE | \
SNDRV_PCM_FMTBIT_U32_BE)
#define FSLDMA_PCM_RATES (SNDRV_PCM_RATE_5512 | SNDRV_PCM_RATE_8000_192000 | \
SNDRV_PCM_RATE_CONTINUOUS)
struct dma_object {
struct snd_soc_platform_driver dai;
dma_addr_t ssi_stx_phys;
dma_addr_t ssi_srx_phys;
unsigned int ssi_fifo_depth;
struct ccsr_dma_channel __iomem *channel;
unsigned int irq;
bool assigned;
char path[1];
};
/*
* The number of DMA links to use. Two is the bare minimum, but if you
* have really small links you might need more.
*/
#define NUM_DMA_LINKS 2
/** fsl_dma_private: p-substream DMA data
*
* Each substream has a 1-to-1 association with a DMA channel.
*
* The link[] array is first because it needs to be aligned on a 32-byte
* boundary, so putting it first will ensure alignment without padding the
* structure.
*
* @link[]: array of link descriptors
* @dma_channel: pointer to the DMA channel's registers
* @irq: IRQ for this DMA channel
* @substream: pointer to the substream object, needed by the ISR
* @ssi_sxx_phys: bus address of the STX or SRX register to use
* @ld_buf_phys: physical address of the LD buffer
* @current_link: index into link[] of the link currently being processed
* @dma_buf_phys: physical address of the DMA buffer
* @dma_buf_next: physical address of the next period to process
* @dma_buf_end: physical address of the byte after the end of the DMA
* @buffer period_size: the size of a single period
* @num_periods: the number of periods in the DMA buffer
*/
struct fsl_dma_private {
struct fsl_dma_link_descriptor link[NUM_DMA_LINKS];
struct ccsr_dma_channel __iomem *dma_channel;
unsigned int irq;
struct snd_pcm_substream *substream;
dma_addr_t ssi_sxx_phys;
unsigned int ssi_fifo_depth;
dma_addr_t ld_buf_phys;
unsigned int current_link;
dma_addr_t dma_buf_phys;
dma_addr_t dma_buf_next;
dma_addr_t dma_buf_end;
size_t period_size;
unsigned int num_periods;
};
/**
* fsl_dma_hardare: define characteristics of the PCM hardware.
*
* The PCM hardware is the Freescale DMA controller. This structure defines
* the capabilities of that hardware.
*
* Since the sampling rate and data format are not controlled by the DMA
* controller, we specify no limits for those values. The only exception is
* period_bytes_min, which is set to a reasonably low value to prevent the
* DMA controller from generating too many interrupts per second.
*
* Since each link descriptor has a 32-bit byte count field, we set
* period_bytes_max to the largest 32-bit number. We also have no maximum
* number of periods.
*
* Note that we specify SNDRV_PCM_INFO_JOINT_DUPLEX here, but only because a
* limitation in the SSI driver requires the sample rates for playback and
* capture to be the same.
*/
static const struct snd_pcm_hardware fsl_dma_hardware = {
.info = SNDRV_PCM_INFO_INTERLEAVED |
SNDRV_PCM_INFO_MMAP |
SNDRV_PCM_INFO_MMAP_VALID |
SNDRV_PCM_INFO_JOINT_DUPLEX |
SNDRV_PCM_INFO_PAUSE,
.formats = FSLDMA_PCM_FORMATS,
.rates = FSLDMA_PCM_RATES,
.rate_min = 5512,
.rate_max = 192000,
.period_bytes_min = 512, /* A reasonable limit */
.period_bytes_max = (u32) -1,
.periods_min = NUM_DMA_LINKS,
.periods_max = (unsigned int) -1,
.buffer_bytes_max = 128 * 1024, /* A reasonable limit */
};
/**
* fsl_dma_abort_stream: tell ALSA that the DMA transfer has aborted
*
* This function should be called by the ISR whenever the DMA controller
* halts data transfer.
*/
static void fsl_dma_abort_stream(struct snd_pcm_substream *substream)
{
unsigned long flags;
snd_pcm_stream_lock_irqsave(substream, flags);
if (snd_pcm_running(substream))
snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN);
snd_pcm_stream_unlock_irqrestore(substream, flags);
}
/**
* fsl_dma_update_pointers - update LD pointers to point to the next period
*
* As each period is completed, this function changes the the link
* descriptor pointers for that period to point to the next period.
*/
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. 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;
if (dma_private->dma_buf_next >= dma_private->dma_buf_end)
dma_private->dma_buf_next = dma_private->dma_buf_phys;
if (++dma_private->current_link >= NUM_DMA_LINKS)
dma_private->current_link = 0;
}
/**
* fsl_dma_isr: interrupt handler for the DMA controller
*
* @irq: IRQ of the DMA channel
* @dev_id: pointer to the dma_private structure for this DMA channel
*/
static irqreturn_t fsl_dma_isr(
|