// SPDX-License-Identifier: GPL-2.0
//
// Freescale DMA ALSA SoC PCM driver
//
// Author: Timur Tabi <timur@freescale.com>
//
// Copyright 2007-2010 Freescale Semiconductor, Inc.
//
// 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 */
#define DRV_NAME "fsl_dma"
/*
* 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)
struct dma_object {
struct snd_soc_component_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;
};
/*
* 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,
.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)
{
snd_pcm_stop_xrun(substream);
}
/**
* fsl_dma_update_pointers - update LD pointers to point to the next period
*
* As each period is completed, this function changes 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(int irq, void *dev_id)
{
struct fsl_dma_private *dma_private = dev_id;
struct snd_pcm_substream *substream = dma_private->substream;
struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);
struct device *dev = rtd->dev;
struct ccsr_dma_channel __iomem *dma_channel = dma_private->dma_channel;
irqreturn_t ret = IRQ_NONE;
u32 sr, sr2 = 0;
/* We got an interrupt, so read the status register to see what we
were interrupted for.
*/
sr = in_be32(&dma_channel->sr);
if (sr & CCSR_DMA_SR_TE) {
dev_err(dev, "dma transmit error\n");
fsl_dma_abort_stream(substream);
sr2 |= CCSR_DMA_SR_TE;
ret = IRQ_HANDLED;
}
if (sr & CCSR_DMA_SR_CH)
ret = IRQ_HANDLED;
if (sr & CCSR_DMA_SR_PE) {
dev_err(dev, "dma programming error\n");
fsl_dma_abort_stream(substream);
sr2 |= CCSR_DMA_SR_PE;
ret = IRQ_HANDLED;
}
if (sr & CCSR_DMA_SR_EOLNI) {
sr2 |= CCSR_DMA_SR_EOLNI;
ret = IRQ_HANDLED;
}
if (sr & CCSR_DMA_SR_CB)
ret = IRQ_HANDLED;
if (sr & CCSR_DMA_SR_EOSI) {
/* Tell ALSA we completed a period. */
snd_pcm_period_elapsed(substream);
/*
* Update our link descriptors to point to the next period. We
* only need to do this if the number of periods is not equal to
* the number of links.
*/
if (dma_private->num_periods != NUM_DMA_LINKS)
fsl_dma_update_pointers(dma_private);
sr2 |= CCSR_DMA_SR_EOSI;
ret = IRQ_HANDLED;
}
if (sr & CCSR_DMA_SR_EOLSI) {
sr2 |= CCSR_DMA_SR_EOLSI;
ret = IRQ_HANDLED;
}
/* Clear the bits that we set */
if (sr2)
out_be32(&dma_channel->sr, sr2);
return ret;
}
/**
* fsl_dma_new: initialize this PCM driver.
*
* 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_soc_component *component,
struct snd_soc_pcm_runtime *rtd)
{
struct snd_card *card = rtd->card->snd_card;
struct snd_pcm *pcm = rtd->pcm;
int ret;
ret = dma_coerce_mask_and_coherent(card->dev, DMA_BIT_MASK(36));
if (ret)
return ret;
return snd_pcm_set_fixed_buffer_all(pcm, SNDRV_DMA_TYPE_DEV,
card->dev,
fsl_dma_hardware.buffer_bytes_max);
}
/**
* fsl_dma_open: open a new substream.
*
* Each substream has its own DMA buffer.
*
* ALSA divides the DMA buffer into N periods. We create NUM_DMA_LINKS link
* descriptors that ping-pong from one period to the next. For example, if
* there are six periods and two link descriptors, this is how they look
* before playback starts:
*
* The last link descriptor
* ____________ points back to the first
* | |
* V |
* ___ ___ |
* | |->| |->|
* |___| |___|
* | |
* | |
* V V
* _________________________________________
* | | | | | | | The DMA buffer is
* | | | | | | | divided into 6 parts
* |______|______|______|______|______|______|
*
* and here's how they look after the first period is finished playing:
*
* ____________
* | |
* V |
* ___ ___ |
* | |->| |->|
* |___| |___|
* | |
* |______________
* | |
* V V
* _________________________________________
* | | | | | | |
* | | | | | | |
* |______|______|______|______|______|______|
*
* The first link descriptor now points to the third period. The DMA
* controller is currently playing the second period. When it finishes, it
* will jump back to the first descriptor and play the third period.
*
* There are four reasons we do this:
*
* 1. The only way to get the DMA controller to automatically restart the
* transfer when it gets to the end of the buffer is to use chaining
* mode. Basic direct mode doesn't offer that feature.
* 2. We need to receive an interrupt at the end of every period. The DMA
* controller can generate an interrupt at the end of every link transfer
* (aka segment). Making each period into a DMA segment will give us the
* interrupts we need.
* 3. By creating only two link descriptors, regardless of the number of
* periods, we do not need to reallocate the link descriptors if the
* number of periods changes.
* 4. All of the audio data is still stored in a single, contiguous DMA
* buffer, which is what ALSA expects. We're just dividing it into
* contiguous parts, and creating a link descriptor for each one.
*/
static int fsl_dma_open(struct snd_soc_component *component,
struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct device *dev = component->dev;
struct dma_object *dma =
container_of(component->driver, struct dma_object, dai);
struct fsl_dma_private *dma_private;
struct ccsr_dma_channel __iomem *dma_channel;
dma_addr_t ld_buf_phys;
u64 temp_link; /* Pointer to next link descriptor */
u32 mr;
int ret = 0;
unsigned int i;
/*
* Reject any DMA buffer whose size is not a multiple of the period
* size. We need to make sure that the DMA buffer can be evenly divided
* into periods.
*/
ret = snd_pcm_hw_constraint_integer(runtime,
SNDRV_PCM_HW_PARAM_PERIODS);
if (ret < 0) {
dev_err(dev, "invalid buffer size\n");
return ret;
}
if (dma->assigned) {
dev_err(dev, "dma channel already assigned\n");
return -EBUSY;
}
dma_private = dma_alloc_coherent(dev, sizeof(struct fsl_dma_private),
&ld_buf_phys, GFP_KERNEL);
if (!dma_private) {
dev_err(dev, "can't allocate dma private data\n");
return -ENOMEM;
}
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
dma_private->ssi_sxx_phys = dma->ssi_stx_phys;
else
dma_private->ssi_sxx_phys = dma->ssi_srx_phys;
dma_private->ssi_fifo_depth = dma->ssi_fifo_depth;
dma_private->dma_channel = dma->channel;
dma_private->irq = dma->irq;
dma_private->substream = substream;
dma_private->ld_buf_phys = ld_buf_phys;
dma_private->dma_buf_phys = substream->dma_buffer.addr;
ret = request_irq(dma_private->irq, fsl_dma_isr, 0, "fsldma-audio",
dma_private);
if (ret) {
dev_err(dev, "can't register ISR for IRQ %u (ret=%i)\n",
dma_private->irq, ret);
dma_free_coherent(dev, sizeof(struct fsl_dma_private),
dma_private, dma_private->ld_buf_phys);
return ret;
}
dma->assigned = true;
snd_soc_set_runtime_hwparams(substream, &fsl_dma_hardware);
runtime->private_data = dma_private;
/* Program the fixed DMA controller parameters */
dma_channel = dma_private->dma_channel;
temp_link = dma_private->ld_buf_phys +
sizeof(struct fsl_dma_link_descriptor);
for (i = 0; i < NUM_DMA_LINKS; i++) {
dma_private->link[i].next = cpu_to_be64(temp_link);
temp_link += sizeof(struct fsl_dma_link_descriptor);
}
/* The last link descriptor points to the first */
dma_private->link[i - 1].next = cpu_to_be64(dma_private->ld_buf_phys);
/* Tell the DMA controller where the first link descriptor is */
out_be32(&dma_channel->clndar,
CCSR_DMA_CLNDAR_ADDR(dma_private->ld_buf_phys));
out_be32(&dma_channel->eclndar,
CCSR_DMA_ECLNDAR_ADDR(dma_private->ld_buf_phys));
/* The manual says the BCR must be clear before enabling EMP */
out_be32(&dma_channel->bcr, 0);
/*
* Program the mode register for interrupts, external master control,
* and source/destination hold. Also clear the Channel Abort bit.
*/
mr = in_be32(&dma_channel->mr) &
~(CCSR_DMA_MR_CA | CCSR_DMA_MR_DAHE | CCSR_DMA_MR_SAHE);
/*
* We want External Master Start and External Master Pause enabled,
* because the SSI is controlling the DMA controller. We want the DMA
* controller to be set up in advance, and then we signal only the SSI
* to start transferring.
*
* We want End-Of-Segment Interrupts enabled, because this will generate
* an interrupt at the end of each segment (each link descriptor
* represents one segment). Each DMA segment is the same thing as an
* ALSA period, so this is how we get an interrupt at the end of every
* period.
*
* We want Error Interrupt enabled, so that we can get an error if
* the DMA controller is mis-programmed somehow.
*/
mr |= CCSR_DMA_MR_EOSIE | CCSR_DMA_MR_EIE | CCSR_DMA_MR_EMP_EN |
CCSR_DMA_MR_EMS_EN;
/* For playback, we want the destination address to be held. For
capture, set the source address to be held. */
mr |= (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) ?
CCSR_DMA_MR_DAHE : CCSR_DMA_MR_SAHE;
out_be32(&dma_channel->mr, mr);
return 0;
}
/**
* fsl_dma_hw_params: continue initializing the DMA links
*
* This function obtains hardware parameters about the opened stream and
* programs the DMA controller accordingly.
*
* One drawback of big-endian is that when copying integers of different
* sizes to a fixed-sized register, the address to which the integer must be
* copied is dependent on the size of the integer.
*
* For example, if P is the address of a 32-bit register, and X is a 32-bit
* integer, then X should be copied to address P. However, if X is a 16-bit
* integer, then it should be copied to P+2. If X is an 8-bit register,
* then it should be copied to P+3.
*
* So for playback of 8-bit samples, the DMA controller must transfer single
* bytes from the DMA buffer to the last byte of the STX0 register, i.e.
* offset by 3 bytes. For 16-bit samples, the offset is two bytes.
*
* For 24-bit samples, the offset is 1 byte. However, the DMA controller
* does not support 3-byte copies (the DAHTS register supports only 1, 2, 4,
* and 8 bytes at a time). So we do not support packed 24-bit samples.
* 24-bit data must be padded to 32 bits.
*/
static int fsl_dma_hw_params(struct snd_soc_component *component,
struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *hw_params)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct fsl_dma_private *dma_private = runtime->private_data;
struct device *dev = component->dev;
/* Number of bits per sample */
unsigned int sample_bits =
snd_pcm_format_physical_width(params_format(hw_params));
/* Number of bytes per frame */
unsigned int sample_bytes = sample_bits / 8;
/* Bus address of SSI STX register */
dma_addr_t ssi_sxx_phys = dma_private->ssi_sxx_phys;
/* Size of the DMA buffer, in bytes */
size_t buffer_size = params_buffer_bytes(hw_params);
/* Number of bytes per period */
size_t period_size = params_period_bytes(hw_params);
/* Pointer to next period */
dma_addr_t temp_addr = substream->dma_buffer.addr;
/* Pointer to DMA controller */
struct ccsr_dma_channel __iomem *dma_channel = dma_private->dma_channel;
u32 mr; /* DMA Mode Register */
unsigned int i;
/* Initialize our DMA tracking variables */
dma_private->period_size = period_size;
dma_private->num_periods = params_periods(hw_params);
dma_private->dma_buf_end = dma_private->dma_buf_phys + buffer_size;
dma_private->dma_buf_next = dma_private->dma_buf_phys +
(NUM_DMA_LINKS * period_size);
if (dma_private->dma_buf_next >= dma_private->dma_buf_end)
/* This happens if the number of periods == NUM_DMA_LINKS */
dma_private->dma_buf_next = dma_private->dma_buf_phys;
mr = in_be32(&dma_channel->mr) & ~(CCSR_DMA_MR_BWC_MASK |
CCSR_DMA_MR_SAHTS_MASK | CCSR_DMA_MR_DAHTS_MASK);
/* Due to a quirk of the SSI's STX register, the target address
* for the DMA operations depends on the sample size. So we calculate
* that offset here. While we're at it, also tell the DMA controller
* how much data to transfer per sample.
*/
switch (sample_bits) {
case 8:
mr |= CCSR_DMA_MR_DAHTS_1 | CCSR_DMA_MR_SAHTS_1;
ssi_sxx_phys += 3;
break;
case 16:
mr |= CCSR_DMA_MR_DAHTS_2 | CCSR_DMA_MR_SAHTS_2;
ssi_sxx_phys += 2;
break;
case 32:
mr |= CCSR_DMA_MR_DAHTS_4 | CCSR_DMA_MR_SAHTS_4;
break;
default:
/* We should never get here */
dev_err(dev, "unsupported sample size %u\n", sample_bits);
return -EINVAL;
}
/*
* BWC determines how many bytes are sent/received before the DMA
* controller checks the SSI to see if it needs to stop. BWC should
* always be a multiple of the frame size, so that we always transmit
* whole frames. Each frame occupies two slots in the FIFO. The
* parameter for CCSR_DMA_MR_BWC() is rounded down the next power of two
* (MR[BWC] can only represent even powers of two).
*
* To simplify the process, we set BWC to the largest value that is
* less than or equal to the FIFO watermark. For playback, this ensures
* that we transfer the maximum amount without overrunning the FIFO.
* For capture, this ensures that we transfer the maximum amount without
* underrunning the FIFO.
*
* f = SSI FIFO depth
* w = SSI watermark value (which equals f - 2)
* b = DMA bandwidth count (in bytes)
* s = sample size (in bytes, which equals frame_size * 2)
*
* For playback, we never transmit more than the transmit FIFO
* watermark, otherwise we might write more data than the FIFO can hold.
* The watermark is equal to the FIFO depth minus two.
*
* For capture, two equations must hold:
* w > f - (b / s)
* w >= b / s
*
* So, b > 2 * s, but b must also be <= s * w. To simplify, we set
* b = s * w, which is equal to
* (dma_private->ssi_fifo_depth - 2) * sample_bytes.
*/
mr |= CCSR_DMA_MR_BWC((dma_private->ssi_fifo_depth - 2) * sample_bytes);
out_be32(&dma_channel->mr, mr);
for (i = 0; i < NUM_DMA_LINKS; i++) {
struct fsl_dma_link_descriptor *link = &dma_private->link[i];
link->count = cpu_to_be32(period_size);
/* 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
* needed if there is a cache, so we need to snoop memory
* addresses only. For playback, that means we snoop the source
* but not the destination. For capture, we snoop the
* destination but not the source.
*
* Note that failing to snoop properly is unlikely to cause
* cache incoherency if the period size is larger than the
* size of L1 cache. This is because filling in one period will
* 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. 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 |
upper_32_bits(temp_addr));
link->dest_addr = cpu_to_be32(ssi_sxx_phys);
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 |
upper_32_bits(ssi_sxx_phys));
link->dest_addr = cpu_to_be32(temp_addr);
link->dest_attr = cpu_to_be32(CCSR_DMA_ATR_SNOOP |
upper_32_bits(temp_addr));
}
temp_addr += period_size;
}
return 0;
}
/**
* fsl_dma_pointer: determine the current position of the DMA transfer
*
* This function is called by ALSA when ALSA wants to know where in the
* stream buffer the hardware currently is.
*
* For playback, the SAR register contains the physical address of the most
* recent DMA transfer. For capture, the value is in the DAR register.
*
* The base address of the buffer is stored in the source_addr field of the
* first link descriptor.
*/
static snd_pcm_uframes_t fsl_dma_pointer(struct snd_soc_component *component,
struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct fsl_dma_private *dma_private = runtime->private_data;
struct device *dev = component->dev;
struct ccsr_dma_channel __iomem *dma_channel = dma_private->dma_channel;
dma_addr_t position;
snd_pcm_uframes_t frames;
/* 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);
#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.
* This means that the DMA controller is not started until the FIFO is
* full. However, ALSA calls this function before that happens, when
* MR.DAR is still zero. In this case, just return zero to indicate
* that nothing has been received yet.
*/
if (!position)
return 0;
if ((position < dma_private->dma_buf_phys) ||
(position > dma_private->dma_buf_end)) {
dev_err(dev, "dma pointer is out of range, halting stream\n");
return SNDRV_PCM_POS_XRUN;
}
frames = bytes_to_frames(runtime, position - dma_private->dma_buf_phys);
/*
* If the current address is just past the end of the buffer, wrap it
* around.
*/
if (frames == runtime->buffer_size)
frames = 0;
return frames;
}
/**
* fsl_dma_hw_free: release resources allocated in fsl_dma_hw_params()
*
* Release the resources allocated in fsl_dma_hw_params() and de-program the
* registers.
*
* This function can be called multiple times.
*/
static int fsl_dma_hw_free(struct snd_soc_component *component,
struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct fsl_dma_private *dma_private = runtime->private_data;
if (dma_private) {
struct ccsr_dma_channel __iomem *dma_channel;
dma_channel = dma_private->dma_channel;
/* Stop the DMA */
out_be32(&dma_channel->mr, CCSR_DMA_MR_CA);
out_be32(&dma_channel->mr, 0);
/* Reset all the other registers */
out_be32(&dma_channel->sr, -1);
out_be32(&dma_channel->clndar, 0);
out_be32(&dma_channel->eclndar, 0);
out_be32(&dma_channel->satr, 0);
out_be32(&dma_channel->sar, 0);
out_be32(&dma_channel->datr, 0);
out_be32(&dma_channel->dar, 0);
out_be32(&dma_channel->bcr, 0);
out_be32(&dma_channel->nlndar, 0);
out_be32(&dma_channel->enlndar, 0);
}
return 0;
}
/**
* fsl_dma_close: close the stream.
*/
static int fsl_dma_close(struct snd_soc_component *component,
struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct fsl_dma_private *dma_private = runtime->private_data;
struct device *dev = component->dev;
struct dma_object *dma =
container_of(component->driver, struct dma_object, dai);
if (dma_private) {
if (dma_private->irq)
free_irq(dma_private->irq, dma_private);
/* Deallocate the fsl_dma_private structure */
dma_free_coherent(dev, sizeof(struct fsl_dma_private),
dma_private, dma_private->ld_buf_phys);
substream->runtime->private_data = NULL;
}
dma->assigned = false;
return 0;
}
/**
* find_ssi_node -- returns the SSI node that points to its DMA channel node
*
* Although this DMA driver attempts to operate independently of the other
* devices, it still needs to determine some information about the SSI device
* that it's working with. Unfortunately, the device tree does not contain
* a pointer from the DMA channel node to the SSI node -- the pointer goes the
* other way. So we need to scan the device tree for SSI nodes until we find
* the one that points to the given DMA channel node. It's ugly, but at least
* it's contained in this one function.
*/
static struct device_node *find_ssi_node(struct device_node *dma_channel_np)
{
struct device_node *ssi_np, *np;
for_each_compatible_node(ssi_np, NULL, "fsl,mpc8610-ssi") {
/* Check each DMA phandle to see if it points to us. We
* assume that device_node pointers are a valid comparison.
*/
np = of_parse_phandle(ssi_np, "fsl,playback-dma", 0);
of_node_put(np);
if (np == dma_channel_np)
return ssi_np;
np = of_parse_phandle(ssi_np, "fsl,capture-dma", 0);
of_node_put(np);
if (np == dma_channel_np)
return ssi_np;
}
return NULL;
}
static int fsl_soc_dma_probe(struct platform_device *pdev)
{
struct dma_object *dma;
struct device_node *np = pdev->dev.of_node;
struct device_node *ssi_np;
struct resource res;
const uint32_t *iprop;
int ret;
/* Find the SSI node that points to us. */
ssi_np = find_ssi_node(np);
if (!ssi_np) {
dev_err(&pdev->dev, "cannot find parent SSI node\n");
return -ENODEV;
}
ret = of_address_to_resource(ssi_np, 0, &res);
if (ret) {
dev_err(&pdev->dev, "could not determine resources for %pOF\n",
ssi_np);
of_node_put(ssi_np);
return ret;
}
dma = kzalloc(sizeof(*dma), GFP_KERNEL);
if (!dma) {
of_node_put(ssi_np);
return -ENOMEM;
}
dma->dai.name = DRV_NAME;
dma->dai.open = fsl_dma_open;
dma->dai.close = fsl_dma_close;
dma->dai.hw_params = fsl_dma_hw_params;
dma->dai.hw_free = fsl_dma_hw_free;
dma->dai.pointer = fsl_dma_pointer;
dma->dai.pcm_construct = fsl_dma_new;
/* Store the SSI-specific information that we need */
dma->ssi_stx_phys = res.start + REG_SSI_STX0;
dma->ssi_srx_phys = res.start + REG_SSI_SRX0;
iprop = of_get_property(ssi_np, "fsl,fifo-depth", NULL);
if (iprop)
dma->ssi_fifo_depth = be32_to_cpup(iprop);
else
/* Older 8610 DTs didn't have the fifo-depth property */
dma->ssi_fifo_depth = 8;
of_node_put(ssi_np);
ret = devm_snd_soc_register_component(&pdev->dev, &dma->dai, NULL, 0);
if (ret) {
dev_err(&pdev->dev, "could not register platform\n");
kfree(dma);
return ret;
}
dma->channel = of_iomap(np, 0);
dma->irq = irq_of_parse_and_map(np, 0);
dev_set_drvdata(&pdev->dev, dma);
return 0;
}
static void fsl_soc_dma_remove(struct platform_device *pdev)
{
struct dma_object *dma = dev_get_drvdata(&pdev->dev);
iounmap(dma->channel);
irq_dispose_mapping(dma->irq);
kfree(dma);
}
static const struct of_device_id fsl_soc_dma_ids[] = {
{ .compatible = "fsl,ssi-dma-channel", },
{}
};
MODULE_DEVICE_TABLE(of, fsl_soc_dma_ids);
static struct platform_driver fsl_soc_dma_driver = {
.driver = {
.name = "fsl-pcm-audio",
.of_match_table = fsl_soc_dma_ids,
},
.probe = fsl_soc_dma_probe,
.remove_new = fsl_soc_dma_remove,
};
module_platform_driver(fsl_soc_dma_driver);
MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
MODULE_DESCRIPTION("Freescale Elo DMA ASoC PCM Driver");
MODULE_LICENSE("GPL v2");