mirror of
https://github.com/torvalds/linux.git
synced 2024-12-25 12:21:37 +00:00
spi: at91-usart: add DMA support
This patch adds support for DMA. Transfers are done with dma only if they are longer than 16 bytes in order to achieve a better performance. DMA setup introduces a little overhead and for transfers shorter than 16 bytes there is no performance improvement. Signed-off-by: Radu Pirea <radu_nicolae.pirea@upb.ro> Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Radu Pirea
Mark Brown
parent
f7b99e5948
commit
c3fdefc2d7
@ -8,9 +8,12 @@
|
||||
|
||||
#include <linux/clk.h>
|
||||
#include <linux/delay.h>
|
||||
#include <linux/dmaengine.h>
|
||||
#include <linux/dma-direction.h>
|
||||
#include <linux/interrupt.h>
|
||||
#include <linux/kernel.h>
|
||||
#include <linux/module.h>
|
||||
#include <linux/of_platform.h>
|
||||
#include <linux/of_gpio.h>
|
||||
#include <linux/pinctrl/consumer.h>
|
||||
#include <linux/platform_device.h>
|
||||
@ -59,6 +62,8 @@
|
||||
|
||||
#define US_INIT \
|
||||
(US_MR_SPI_MASTER | US_MR_CHRL | US_MR_CLKO | US_MR_WRDBT)
|
||||
#define US_DMA_MIN_BYTES 16
|
||||
#define US_DMA_TIMEOUT (msecs_to_jiffies(1000))
|
||||
|
||||
/* Register access macros */
|
||||
#define at91_usart_spi_readl(port, reg) \
|
||||
@ -72,14 +77,19 @@
|
||||
writeb_relaxed((value), (port)->regs + US_##reg)
|
||||
|
||||
struct at91_usart_spi {
|
||||
struct platform_device *mpdev;
|
||||
struct spi_transfer *current_transfer;
|
||||
void __iomem *regs;
|
||||
struct device *dev;
|
||||
struct clk *clk;
|
||||
|
||||
struct completion xfer_completion;
|
||||
|
||||
/*used in interrupt to protect data reading*/
|
||||
spinlock_t lock;
|
||||
|
||||
phys_addr_t phybase;
|
||||
|
||||
int irq;
|
||||
unsigned int current_tx_remaining_bytes;
|
||||
unsigned int current_rx_remaining_bytes;
|
||||
@ -88,8 +98,182 @@ struct at91_usart_spi {
|
||||
u32 status;
|
||||
|
||||
bool xfer_failed;
|
||||
bool use_dma;
|
||||
};
|
||||
|
||||
static void dma_callback(void *data)
|
||||
{
|
||||
struct spi_controller *ctlr = data;
|
||||
struct at91_usart_spi *aus = spi_master_get_devdata(ctlr);
|
||||
|
||||
at91_usart_spi_writel(aus, IER, US_IR_RXRDY);
|
||||
aus->current_rx_remaining_bytes = 0;
|
||||
complete(&aus->xfer_completion);
|
||||
}
|
||||
|
||||
static bool at91_usart_spi_can_dma(struct spi_controller *ctrl,
|
||||
struct spi_device *spi,
|
||||
struct spi_transfer *xfer)
|
||||
{
|
||||
struct at91_usart_spi *aus = spi_master_get_devdata(ctrl);
|
||||
|
||||
return aus->use_dma && xfer->len >= US_DMA_MIN_BYTES;
|
||||
}
|
||||
|
||||
static int at91_usart_spi_configure_dma(struct spi_controller *ctlr,
|
||||
struct at91_usart_spi *aus)
|
||||
{
|
||||
struct dma_slave_config slave_config;
|
||||
struct device *dev = &aus->mpdev->dev;
|
||||
phys_addr_t phybase = aus->phybase;
|
||||
dma_cap_mask_t mask;
|
||||
int err = 0;
|
||||
|
||||
dma_cap_zero(mask);
|
||||
dma_cap_set(DMA_SLAVE, mask);
|
||||
|
||||
ctlr->dma_tx = dma_request_slave_channel_reason(dev, "tx");
|
||||
if (IS_ERR_OR_NULL(ctlr->dma_tx)) {
|
||||
if (IS_ERR(ctlr->dma_tx)) {
|
||||
err = PTR_ERR(ctlr->dma_tx);
|
||||
goto at91_usart_spi_error_clear;
|
||||
}
|
||||
|
||||
dev_dbg(dev,
|
||||
"DMA TX channel not available, SPI unable to use DMA\n");
|
||||
err = -EBUSY;
|
||||
goto at91_usart_spi_error_clear;
|
||||
}
|
||||
|
||||
ctlr->dma_rx = dma_request_slave_channel_reason(dev, "rx");
|
||||
if (IS_ERR_OR_NULL(ctlr->dma_rx)) {
|
||||
if (IS_ERR(ctlr->dma_rx)) {
|
||||
err = PTR_ERR(ctlr->dma_rx);
|
||||
goto at91_usart_spi_error;
|
||||
}
|
||||
|
||||
dev_dbg(dev,
|
||||
"DMA RX channel not available, SPI unable to use DMA\n");
|
||||
err = -EBUSY;
|
||||
goto at91_usart_spi_error;
|
||||
}
|
||||
|
||||
slave_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
|
||||
slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
|
||||
slave_config.dst_addr = (dma_addr_t)phybase + US_THR;
|
||||
slave_config.src_addr = (dma_addr_t)phybase + US_RHR;
|
||||
slave_config.src_maxburst = 1;
|
||||
slave_config.dst_maxburst = 1;
|
||||
slave_config.device_fc = false;
|
||||
|
||||
slave_config.direction = DMA_DEV_TO_MEM;
|
||||
if (dmaengine_slave_config(ctlr->dma_rx, &slave_config)) {
|
||||
dev_err(&ctlr->dev,
|
||||
"failed to configure rx dma channel\n");
|
||||
err = -EINVAL;
|
||||
goto at91_usart_spi_error;
|
||||
}
|
||||
|
||||
slave_config.direction = DMA_MEM_TO_DEV;
|
||||
if (dmaengine_slave_config(ctlr->dma_tx, &slave_config)) {
|
||||
dev_err(&ctlr->dev,
|
||||
"failed to configure tx dma channel\n");
|
||||
err = -EINVAL;
|
||||
goto at91_usart_spi_error;
|
||||
}
|
||||
|
||||
aus->use_dma = true;
|
||||
return 0;
|
||||
|
||||
at91_usart_spi_error:
|
||||
if (!IS_ERR_OR_NULL(ctlr->dma_tx))
|
||||
dma_release_channel(ctlr->dma_tx);
|
||||
if (!IS_ERR_OR_NULL(ctlr->dma_rx))
|
||||
dma_release_channel(ctlr->dma_rx);
|
||||
ctlr->dma_tx = NULL;
|
||||
ctlr->dma_rx = NULL;
|
||||
|
||||
at91_usart_spi_error_clear:
|
||||
return err;
|
||||
}
|
||||
|
||||
static void at91_usart_spi_release_dma(struct spi_controller *ctlr)
|
||||
{
|
||||
if (ctlr->dma_rx)
|
||||
dma_release_channel(ctlr->dma_rx);
|
||||
if (ctlr->dma_tx)
|
||||
dma_release_channel(ctlr->dma_tx);
|
||||
}
|
||||
|
||||
static void at91_usart_spi_stop_dma(struct spi_controller *ctlr)
|
||||
{
|
||||
if (ctlr->dma_rx)
|
||||
dmaengine_terminate_all(ctlr->dma_rx);
|
||||
if (ctlr->dma_tx)
|
||||
dmaengine_terminate_all(ctlr->dma_tx);
|
||||
}
|
||||
|
||||
static int at91_usart_spi_dma_transfer(struct spi_controller *ctlr,
|
||||
struct spi_transfer *xfer)
|
||||
{
|
||||
struct at91_usart_spi *aus = spi_master_get_devdata(ctlr);
|
||||
struct dma_chan *rxchan = ctlr->dma_rx;
|
||||
struct dma_chan *txchan = ctlr->dma_tx;
|
||||
struct dma_async_tx_descriptor *rxdesc;
|
||||
struct dma_async_tx_descriptor *txdesc;
|
||||
dma_cookie_t cookie;
|
||||
|
||||
/* Disable RX interrupt */
|
||||
at91_usart_spi_writel(aus, IDR, US_IR_RXRDY);
|
||||
|
||||
rxdesc = dmaengine_prep_slave_sg(rxchan,
|
||||
xfer->rx_sg.sgl,
|
||||
xfer->rx_sg.nents,
|
||||
DMA_DEV_TO_MEM,
|
||||
DMA_PREP_INTERRUPT |
|
||||
DMA_CTRL_ACK);
|
||||
if (!rxdesc)
|
||||
goto at91_usart_spi_err_dma;
|
||||
|
||||
txdesc = dmaengine_prep_slave_sg(txchan,
|
||||
xfer->tx_sg.sgl,
|
||||
xfer->tx_sg.nents,
|
||||
DMA_MEM_TO_DEV,
|
||||
DMA_PREP_INTERRUPT |
|
||||
DMA_CTRL_ACK);
|
||||
if (!txdesc)
|
||||
goto at91_usart_spi_err_dma;
|
||||
|
||||
rxdesc->callback = dma_callback;
|
||||
rxdesc->callback_param = ctlr;
|
||||
|
||||
cookie = rxdesc->tx_submit(rxdesc);
|
||||
if (dma_submit_error(cookie))
|
||||
goto at91_usart_spi_err_dma;
|
||||
|
||||
cookie = txdesc->tx_submit(txdesc);
|
||||
if (dma_submit_error(cookie))
|
||||
goto at91_usart_spi_err_dma;
|
||||
|
||||
rxchan->device->device_issue_pending(rxchan);
|
||||
txchan->device->device_issue_pending(txchan);
|
||||
|
||||
return 0;
|
||||
|
||||
at91_usart_spi_err_dma:
|
||||
/* Enable RX interrupt if something fails and fallback to PIO */
|
||||
at91_usart_spi_writel(aus, IER, US_IR_RXRDY);
|
||||
at91_usart_spi_stop_dma(ctlr);
|
||||
|
||||
return -ENOMEM;
|
||||
}
|
||||
|
||||
static unsigned long at91_usart_spi_dma_timeout(struct at91_usart_spi *aus)
|
||||
{
|
||||
return wait_for_completion_timeout(&aus->xfer_completion,
|
||||
US_DMA_TIMEOUT);
|
||||
}
|
||||
|
||||
static inline u32 at91_usart_spi_tx_ready(struct at91_usart_spi *aus)
|
||||
{
|
||||
return aus->status & US_IR_TXRDY;
|
||||
@ -216,6 +400,8 @@ static int at91_usart_spi_transfer_one(struct spi_controller *ctlr,
|
||||
struct spi_transfer *xfer)
|
||||
{
|
||||
struct at91_usart_spi *aus = spi_master_get_devdata(ctlr);
|
||||
unsigned long dma_timeout = 0;
|
||||
int ret = 0;
|
||||
|
||||
at91_usart_spi_set_xfer_speed(aus, xfer);
|
||||
aus->xfer_failed = false;
|
||||
@ -225,8 +411,25 @@ static int at91_usart_spi_transfer_one(struct spi_controller *ctlr,
|
||||
|
||||
while ((aus->current_tx_remaining_bytes ||
|
||||
aus->current_rx_remaining_bytes) && !aus->xfer_failed) {
|
||||
at91_usart_spi_read_status(aus);
|
||||
at91_usart_spi_tx(aus);
|
||||
reinit_completion(&aus->xfer_completion);
|
||||
if (at91_usart_spi_can_dma(ctlr, spi, xfer) &&
|
||||
!ret) {
|
||||
ret = at91_usart_spi_dma_transfer(ctlr, xfer);
|
||||
if (ret)
|
||||
continue;
|
||||
|
||||
dma_timeout = at91_usart_spi_dma_timeout(aus);
|
||||
|
||||
if (WARN_ON(dma_timeout == 0)) {
|
||||
dev_err(&spi->dev, "DMA transfer timeout\n");
|
||||
return -EIO;
|
||||
}
|
||||
aus->current_tx_remaining_bytes = 0;
|
||||
} else {
|
||||
at91_usart_spi_read_status(aus);
|
||||
at91_usart_spi_tx(aus);
|
||||
}
|
||||
|
||||
cpu_relax();
|
||||
}
|
||||
|
||||
@ -345,6 +548,7 @@ static int at91_usart_spi_probe(struct platform_device *pdev)
|
||||
controller->transfer_one = at91_usart_spi_transfer_one;
|
||||
controller->prepare_message = at91_usart_spi_prepare_message;
|
||||
controller->unprepare_message = at91_usart_spi_unprepare_message;
|
||||
controller->can_dma = at91_usart_spi_can_dma;
|
||||
controller->cleanup = at91_usart_spi_cleanup;
|
||||
controller->max_speed_hz = DIV_ROUND_UP(clk_get_rate(clk),
|
||||
US_MIN_CLK_DIV);
|
||||
@ -376,7 +580,17 @@ static int at91_usart_spi_probe(struct platform_device *pdev)
|
||||
aus->spi_clk = clk_get_rate(clk);
|
||||
at91_usart_spi_init(aus);
|
||||
|
||||
aus->phybase = regs->start;
|
||||
|
||||
aus->mpdev = to_platform_device(pdev->dev.parent);
|
||||
|
||||
ret = at91_usart_spi_configure_dma(controller, aus);
|
||||
if (ret)
|
||||
goto at91_usart_fail_dma;
|
||||
|
||||
spin_lock_init(&aus->lock);
|
||||
init_completion(&aus->xfer_completion);
|
||||
|
||||
ret = devm_spi_register_master(&pdev->dev, controller);
|
||||
if (ret)
|
||||
goto at91_usart_fail_register_master;
|
||||
@ -389,6 +603,8 @@ static int at91_usart_spi_probe(struct platform_device *pdev)
|
||||
return 0;
|
||||
|
||||
at91_usart_fail_register_master:
|
||||
at91_usart_spi_release_dma(controller);
|
||||
at91_usart_fail_dma:
|
||||
clk_disable_unprepare(clk);
|
||||
at91_usart_spi_probe_fail:
|
||||
spi_master_put(controller);
|
||||
@ -453,6 +669,7 @@ static int at91_usart_spi_remove(struct platform_device *pdev)
|
||||
struct spi_controller *ctlr = platform_get_drvdata(pdev);
|
||||
struct at91_usart_spi *aus = spi_master_get_devdata(ctlr);
|
||||
|
||||
at91_usart_spi_release_dma(ctlr);
|
||||
clk_disable_unprepare(aus->clk);
|
||||
|
||||
return 0;
|
||||
|
||||
Loading…
Reference in New Issue
Block a user