spi/ep93xx: add DMA support

This patch adds DMA support for the EP93xx SPI driver. By default the DMA is
not enabled but it can be enabled by setting ep93xx_spi_info.use_dma to true
in board configuration file.

Note that the SPI driver still uses PIO for small transfers (<= 8 bytes) for
performance reasons.

Signed-off-by: Mika Westerberg <mika.westerberg@iki.fi>
Acked-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This commit is contained in:
Mika Westerberg 2011-05-29 13:10:06 +03:00 committed by Vinod Koul
parent 8e4a93008d
commit d41071575b
4 changed files with 308 additions and 13 deletions

View File

@ -88,6 +88,16 @@ static void __init ts72xx_init_machine(void)
ARRAY_SIZE(ts72xx_spi_devices));
}
The driver can use DMA for the transfers also. In this case ts72xx_spi_info
becomes:
static struct ep93xx_spi_info ts72xx_spi_info = {
.num_chipselect = ARRAY_SIZE(ts72xx_spi_devices),
.use_dma = true;
};
Note that CONFIG_EP93XX_DMA should be enabled as well.
Thanks to
=========
Martin Guy, H. Hartley Sweeten and others who helped me during development of

View File

@ -488,11 +488,15 @@ static struct resource ep93xx_spi_resources[] = {
},
};
static u64 ep93xx_spi_dma_mask = DMA_BIT_MASK(32);
static struct platform_device ep93xx_spi_device = {
.name = "ep93xx-spi",
.id = 0,
.dev = {
.platform_data = &ep93xx_spi_master_data,
.platform_data = &ep93xx_spi_master_data,
.coherent_dma_mask = DMA_BIT_MASK(32),
.dma_mask = &ep93xx_spi_dma_mask,
},
.num_resources = ARRAY_SIZE(ep93xx_spi_resources),
.resource = ep93xx_spi_resources,

View File

@ -7,9 +7,11 @@ struct spi_device;
* struct ep93xx_spi_info - EP93xx specific SPI descriptor
* @num_chipselect: number of chip selects on this board, must be
* at least one
* @use_dma: use DMA for the transfers
*/
struct ep93xx_spi_info {
int num_chipselect;
bool use_dma;
};
/**

View File

@ -1,7 +1,7 @@
/*
* Driver for Cirrus Logic EP93xx SPI controller.
*
* Copyright (c) 2010 Mika Westerberg
* Copyright (C) 2010-2011 Mika Westerberg
*
* Explicit FIFO handling code was inspired by amba-pl022 driver.
*
@ -21,13 +21,16 @@
#include <linux/err.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/dmaengine.h>
#include <linux/bitops.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/workqueue.h>
#include <linux/sched.h>
#include <linux/scatterlist.h>
#include <linux/spi/spi.h>
#include <mach/dma.h>
#include <mach/ep93xx_spi.h>
#define SSPCR0 0x0000
@ -71,6 +74,7 @@
* @pdev: pointer to platform device
* @clk: clock for the controller
* @regs_base: pointer to ioremap()'d registers
* @sspdr_phys: physical address of the SSPDR register
* @irq: IRQ number used by the driver
* @min_rate: minimum clock rate (in Hz) supported by the controller
* @max_rate: maximum clock rate (in Hz) supported by the controller
@ -84,6 +88,14 @@
* @rx: current byte in transfer to receive
* @fifo_level: how full is FIFO (%0..%SPI_FIFO_SIZE - %1). Receiving one
* frame decreases this level and sending one frame increases it.
* @dma_rx: RX DMA channel
* @dma_tx: TX DMA channel
* @dma_rx_data: RX parameters passed to the DMA engine
* @dma_tx_data: TX parameters passed to the DMA engine
* @rx_sgt: sg table for RX transfers
* @tx_sgt: sg table for TX transfers
* @zeropage: dummy page used as RX buffer when only TX buffer is passed in by
* the client
*
* This structure holds EP93xx SPI controller specific information. When
* @running is %true, driver accepts transfer requests from protocol drivers.
@ -100,6 +112,7 @@ struct ep93xx_spi {
const struct platform_device *pdev;
struct clk *clk;
void __iomem *regs_base;
unsigned long sspdr_phys;
int irq;
unsigned long min_rate;
unsigned long max_rate;
@ -112,6 +125,13 @@ struct ep93xx_spi {
size_t tx;
size_t rx;
size_t fifo_level;
struct dma_chan *dma_rx;
struct dma_chan *dma_tx;
struct ep93xx_dma_data dma_rx_data;
struct ep93xx_dma_data dma_tx_data;
struct sg_table rx_sgt;
struct sg_table tx_sgt;
void *zeropage;
};
/**
@ -496,14 +516,195 @@ static int ep93xx_spi_read_write(struct ep93xx_spi *espi)
espi->fifo_level++;
}
if (espi->rx == t->len) {
msg->actual_length += t->len;
if (espi->rx == t->len)
return 0;
}
return -EINPROGRESS;
}
static void ep93xx_spi_pio_transfer(struct ep93xx_spi *espi)
{
/*
* Now everything is set up for the current transfer. We prime the TX
* FIFO, enable interrupts, and wait for the transfer to complete.
*/
if (ep93xx_spi_read_write(espi)) {
ep93xx_spi_enable_interrupts(espi);
wait_for_completion(&espi->wait);
}
}
/**
* ep93xx_spi_dma_prepare() - prepares a DMA transfer
* @espi: ep93xx SPI controller struct
* @dir: DMA transfer direction
*
* Function configures the DMA, maps the buffer and prepares the DMA
* descriptor. Returns a valid DMA descriptor in case of success and ERR_PTR
* in case of failure.
*/
static struct dma_async_tx_descriptor *
ep93xx_spi_dma_prepare(struct ep93xx_spi *espi, enum dma_data_direction dir)
{
struct spi_transfer *t = espi->current_msg->state;
struct dma_async_tx_descriptor *txd;
enum dma_slave_buswidth buswidth;
struct dma_slave_config conf;
struct scatterlist *sg;
struct sg_table *sgt;
struct dma_chan *chan;
const void *buf, *pbuf;
size_t len = t->len;
int i, ret, nents;
if (bits_per_word(espi) > 8)
buswidth = DMA_SLAVE_BUSWIDTH_2_BYTES;
else
buswidth = DMA_SLAVE_BUSWIDTH_1_BYTE;
memset(&conf, 0, sizeof(conf));
conf.direction = dir;
if (dir == DMA_FROM_DEVICE) {
chan = espi->dma_rx;
buf = t->rx_buf;
sgt = &espi->rx_sgt;
conf.src_addr = espi->sspdr_phys;
conf.src_addr_width = buswidth;
} else {
chan = espi->dma_tx;
buf = t->tx_buf;
sgt = &espi->tx_sgt;
conf.dst_addr = espi->sspdr_phys;
conf.dst_addr_width = buswidth;
}
ret = dmaengine_slave_config(chan, &conf);
if (ret)
return ERR_PTR(ret);
/*
* We need to split the transfer into PAGE_SIZE'd chunks. This is
* because we are using @espi->zeropage to provide a zero RX buffer
* for the TX transfers and we have only allocated one page for that.
*
* For performance reasons we allocate a new sg_table only when
* needed. Otherwise we will re-use the current one. Eventually the
* last sg_table is released in ep93xx_spi_release_dma().
*/
nents = DIV_ROUND_UP(len, PAGE_SIZE);
if (nents != sgt->nents) {
sg_free_table(sgt);
ret = sg_alloc_table(sgt, nents, GFP_KERNEL);
if (ret)
return ERR_PTR(ret);
}
pbuf = buf;
for_each_sg(sgt->sgl, sg, sgt->nents, i) {
size_t bytes = min_t(size_t, len, PAGE_SIZE);
if (buf) {
sg_set_page(sg, virt_to_page(pbuf), bytes,
offset_in_page(pbuf));
} else {
sg_set_page(sg, virt_to_page(espi->zeropage),
bytes, 0);
}
pbuf += bytes;
len -= bytes;
}
if (WARN_ON(len)) {
dev_warn(&espi->pdev->dev, "len = %d expected 0!", len);
return ERR_PTR(-EINVAL);
}
nents = dma_map_sg(chan->device->dev, sgt->sgl, sgt->nents, dir);
if (!nents)
return ERR_PTR(-ENOMEM);
txd = chan->device->device_prep_slave_sg(chan, sgt->sgl, nents,
dir, DMA_CTRL_ACK);
if (!txd) {
dma_unmap_sg(chan->device->dev, sgt->sgl, sgt->nents, dir);
return ERR_PTR(-ENOMEM);
}
return txd;
}
/**
* ep93xx_spi_dma_finish() - finishes with a DMA transfer
* @espi: ep93xx SPI controller struct
* @dir: DMA transfer direction
*
* Function finishes with the DMA transfer. After this, the DMA buffer is
* unmapped.
*/
static void ep93xx_spi_dma_finish(struct ep93xx_spi *espi,
enum dma_data_direction dir)
{
struct dma_chan *chan;
struct sg_table *sgt;
if (dir == DMA_FROM_DEVICE) {
chan = espi->dma_rx;
sgt = &espi->rx_sgt;
} else {
chan = espi->dma_tx;
sgt = &espi->tx_sgt;
}
dma_unmap_sg(chan->device->dev, sgt->sgl, sgt->nents, dir);
}
static void ep93xx_spi_dma_callback(void *callback_param)
{
complete(callback_param);
}
static void ep93xx_spi_dma_transfer(struct ep93xx_spi *espi)
{
struct spi_message *msg = espi->current_msg;
struct dma_async_tx_descriptor *rxd, *txd;
rxd = ep93xx_spi_dma_prepare(espi, DMA_FROM_DEVICE);
if (IS_ERR(rxd)) {
dev_err(&espi->pdev->dev, "DMA RX failed: %ld\n", PTR_ERR(rxd));
msg->status = PTR_ERR(rxd);
return;
}
txd = ep93xx_spi_dma_prepare(espi, DMA_TO_DEVICE);
if (IS_ERR(txd)) {
ep93xx_spi_dma_finish(espi, DMA_FROM_DEVICE);
dev_err(&espi->pdev->dev, "DMA TX failed: %ld\n", PTR_ERR(rxd));
msg->status = PTR_ERR(txd);
return;
}
/* We are ready when RX is done */
rxd->callback = ep93xx_spi_dma_callback;
rxd->callback_param = &espi->wait;
/* Now submit both descriptors and wait while they finish */
dmaengine_submit(rxd);
dmaengine_submit(txd);
dma_async_issue_pending(espi->dma_rx);
dma_async_issue_pending(espi->dma_tx);
wait_for_completion(&espi->wait);
ep93xx_spi_dma_finish(espi, DMA_TO_DEVICE);
ep93xx_spi_dma_finish(espi, DMA_FROM_DEVICE);
}
/**
* ep93xx_spi_process_transfer() - processes one SPI transfer
* @espi: ep93xx SPI controller struct
@ -556,13 +757,14 @@ static void ep93xx_spi_process_transfer(struct ep93xx_spi *espi,
espi->tx = 0;
/*
* Now everything is set up for the current transfer. We prime the TX
* FIFO, enable interrupts, and wait for the transfer to complete.
* There is no point of setting up DMA for the transfers which will
* fit into the FIFO and can be transferred with a single interrupt.
* So in these cases we will be using PIO and don't bother for DMA.
*/
if (ep93xx_spi_read_write(espi)) {
ep93xx_spi_enable_interrupts(espi);
wait_for_completion(&espi->wait);
}
if (espi->dma_rx && t->len > SPI_FIFO_SIZE)
ep93xx_spi_dma_transfer(espi);
else
ep93xx_spi_pio_transfer(espi);
/*
* In case of error during transmit, we bail out from processing
@ -571,6 +773,8 @@ static void ep93xx_spi_process_transfer(struct ep93xx_spi *espi,
if (msg->status)
return;
msg->actual_length += t->len;
/*
* After this transfer is finished, perform any possible
* post-transfer actions requested by the protocol driver.
@ -752,6 +956,75 @@ static irqreturn_t ep93xx_spi_interrupt(int irq, void *dev_id)
return IRQ_HANDLED;
}
static bool ep93xx_spi_dma_filter(struct dma_chan *chan, void *filter_param)
{
if (ep93xx_dma_chan_is_m2p(chan))
return false;
chan->private = filter_param;
return true;
}
static int ep93xx_spi_setup_dma(struct ep93xx_spi *espi)
{
dma_cap_mask_t mask;
int ret;
espi->zeropage = (void *)get_zeroed_page(GFP_KERNEL);
if (!espi->zeropage)
return -ENOMEM;
dma_cap_zero(mask);
dma_cap_set(DMA_SLAVE, mask);
espi->dma_rx_data.port = EP93XX_DMA_SSP;
espi->dma_rx_data.direction = DMA_FROM_DEVICE;
espi->dma_rx_data.name = "ep93xx-spi-rx";
espi->dma_rx = dma_request_channel(mask, ep93xx_spi_dma_filter,
&espi->dma_rx_data);
if (!espi->dma_rx) {
ret = -ENODEV;
goto fail_free_page;
}
espi->dma_tx_data.port = EP93XX_DMA_SSP;
espi->dma_tx_data.direction = DMA_TO_DEVICE;
espi->dma_tx_data.name = "ep93xx-spi-tx";
espi->dma_tx = dma_request_channel(mask, ep93xx_spi_dma_filter,
&espi->dma_tx_data);
if (!espi->dma_tx) {
ret = -ENODEV;
goto fail_release_rx;
}
return 0;
fail_release_rx:
dma_release_channel(espi->dma_rx);
espi->dma_rx = NULL;
fail_free_page:
free_page((unsigned long)espi->zeropage);
return ret;
}
static void ep93xx_spi_release_dma(struct ep93xx_spi *espi)
{
if (espi->dma_rx) {
dma_release_channel(espi->dma_rx);
sg_free_table(&espi->rx_sgt);
}
if (espi->dma_tx) {
dma_release_channel(espi->dma_tx);
sg_free_table(&espi->tx_sgt);
}
if (espi->zeropage)
free_page((unsigned long)espi->zeropage);
}
static int __init ep93xx_spi_probe(struct platform_device *pdev)
{
struct spi_master *master;
@ -818,6 +1091,7 @@ static int __init ep93xx_spi_probe(struct platform_device *pdev)
goto fail_put_clock;
}
espi->sspdr_phys = res->start + SSPDR;
espi->regs_base = ioremap(res->start, resource_size(res));
if (!espi->regs_base) {
dev_err(&pdev->dev, "failed to map resources\n");
@ -832,10 +1106,13 @@ static int __init ep93xx_spi_probe(struct platform_device *pdev)
goto fail_unmap_regs;
}
if (info->use_dma && ep93xx_spi_setup_dma(espi))
dev_warn(&pdev->dev, "DMA setup failed. Falling back to PIO\n");
espi->wq = create_singlethread_workqueue("ep93xx_spid");
if (!espi->wq) {
dev_err(&pdev->dev, "unable to create workqueue\n");
goto fail_free_irq;
goto fail_free_dma;
}
INIT_WORK(&espi->msg_work, ep93xx_spi_work);
INIT_LIST_HEAD(&espi->msg_queue);
@ -857,7 +1134,8 @@ static int __init ep93xx_spi_probe(struct platform_device *pdev)
fail_free_queue:
destroy_workqueue(espi->wq);
fail_free_irq:
fail_free_dma:
ep93xx_spi_release_dma(espi);
free_irq(espi->irq, espi);
fail_unmap_regs:
iounmap(espi->regs_base);
@ -901,6 +1179,7 @@ static int __exit ep93xx_spi_remove(struct platform_device *pdev)
}
spin_unlock_irq(&espi->lock);
ep93xx_spi_release_dma(espi);
free_irq(espi->irq, espi);
iounmap(espi->regs_base);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);