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Message-ID: <20130403102332.GA4633@lnx-rg>
Date: Wed, 3 Apr 2013 12:23:35 +0200
From: Richard GENOUD <richard.genoud@...il.com>
To: Wenyou Yang <wenyou.yang@...el.com>
Cc: linux-arm-kernel@...ts.infradead.org, grant.likely@...retlab.ca,
broonie@...nsource.wolfsonmicro.com, plagnioj@...osoft.com,
nicolas.ferre@...el.com, JM.Lin@...el.com,
spi-devel-general@...ts.sourceforge.net,
spi-devel-general@...ts.sourceforge.ne,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 3/8] spi/spi-atmel: add dmaengine support
On [mer., 03.04.2013 13:59:19], Wenyou Yang wrote:
> From: Nicolas Ferre <nicolas.ferre@...el.com>
>
> Add dmaengine support.
>
> Using "has_dma_support" member of struct is used to select
> the transfer mode: dmaengine or pdc.
>
> For the dmaengine transfer mode, it supports both 8 bits and 16 bits transfer.
>
> For the dmaengine transfer mode, if it fails to config dmaengine,
> or if the message length is less than 16 bytes, it will use the PIO transfer mode.
>
> Signed-off-by: Nicolas Ferre <nicolas.ferre@...el.com>
> [wenyou.yang@...el.com: using "has_dma_support" to select dmaengine as the spi xfer mode]
> [wenyou.yang@...el.com: fix DMA: OOPS if buffer > 4096 bytes]
> [wenyou.yang@...el.com: submit the patch]
> Signed-off-by: Wenyou Yang <wenyou.yang@...el.com>
> Cc: richard.genoud@...il.com
> Cc: spi-devel-general@...ts.sourceforge.ne
> Cc: linux-kernel@...r.kernel.org
> [richard.genoud@...il.com: update with dmaengine interface]
> [richard.genoud@...il.com: fix __init/__devinit sections mismatch]
> [richard.genoud@...il.com: adapt to slave_config changes]
> [richard.genoud@...il.com: add support t0 16 bits transfer]
> ---
> This patch is based on the original patch from Nicolas
> - add dmaengine support
> and squash the below patches from Richard Genoud <richard.genoud@...il.com>
> - update with dmaengine interface
> - fix __init/__devinit sections mismatch
> - fix spi-atmel driver to adapt to slave_config changes
> - correct 16 bits transfers with DMA
>
> Hi, Richard,
>
> Could you sign your signature in this patch?
>
> Best Regards,
> Wenyou Yang
>
> drivers/spi/spi-atmel.c | 587 +++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 566 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
> index 2df562f..759d83a 100644
> --- a/drivers/spi/spi-atmel.c
> +++ b/drivers/spi/spi-atmel.c
> @@ -15,11 +15,13 @@
> #include <linux/platform_device.h>
> #include <linux/delay.h>
> #include <linux/dma-mapping.h>
> +#include <linux/dmaengine.h>
> #include <linux/err.h>
> #include <linux/interrupt.h>
> #include <linux/spi/spi.h>
> #include <linux/slab.h>
> #include <linux/platform_data/atmel.h>
> +#include <linux/platform_data/dma-atmel.h>
> #include <linux/of.h>
>
> #include <linux/io.h>
> @@ -182,6 +184,22 @@
> #define spi_writel(port,reg,value) \
> __raw_writel((value), (port)->regs + SPI_##reg)
>
> +/* use PIO for small transfers, avoiding DMA setup/teardown overhead and
> + * cache operations; better heuristics consider wordsize and bitrate.
> + */
> +#define DMA_MIN_BYTES 16
> +
> +struct atmel_spi_dma {
> + struct dma_chan *chan_rx;
> + struct dma_chan *chan_tx;
> + struct scatterlist sgrx;
> + struct scatterlist sgtx;
> + struct dma_async_tx_descriptor *data_desc_rx;
> + struct dma_async_tx_descriptor *data_desc_tx;
> +
> + struct at_dma_slave dma_slave;
> +};
> +
> struct atmel_spi_caps {
> bool is_spi2;
> bool has_wdrbt;
> @@ -206,16 +224,23 @@ struct atmel_spi {
>
> u8 stopping;
> struct list_head queue;
> + struct tasklet_struct tasklet;
> struct spi_transfer *current_transfer;
> unsigned long current_remaining_bytes;
> struct spi_transfer *next_transfer;
> unsigned long next_remaining_bytes;
> int done_status;
>
> + /* scratch buffer */
> void *buffer;
> dma_addr_t buffer_dma;
>
> struct atmel_spi_caps caps;
> +
> + bool use_dma;
> + bool use_pdc;
> + /* dmaengine data */
> + struct atmel_spi_dma dma;
> };
>
> /* Controller-specific per-slave state */
> @@ -284,6 +309,7 @@ static void cs_activate(struct atmel_spi *as, struct spi_device *spi)
> | SPI_BIT(MODFDIS)
> | SPI_BIT(MSTR));
> }
> +
> mr = spi_readl(as, MR);
> gpio_set_value(asd->npcs_pin, active);
> } else {
> @@ -344,6 +370,12 @@ static void atmel_spi_unlock(struct atmel_spi *as)
> spin_unlock_irqrestore(&as->lock, as->flags);
> }
>
> +static inline bool atmel_spi_use_dma(struct atmel_spi *as,
> + struct spi_transfer *xfer)
> +{
> + return as->use_dma && xfer->len >= DMA_MIN_BYTES;
> +}
> +
> static inline int atmel_spi_xfer_is_last(struct spi_message *msg,
> struct spi_transfer *xfer)
> {
> @@ -355,6 +387,265 @@ static inline int atmel_spi_xfer_can_be_chained(struct spi_transfer *xfer)
> return xfer->delay_usecs == 0 && !xfer->cs_change;
> }
>
> +static int atmel_spi_dma_slave_config(struct atmel_spi *as,
> + struct dma_slave_config *slave_config,
> + u8 bits_per_word)
> +{
> + int err = 0;
> +
> + if (bits_per_word > 8) {
> + slave_config->dst_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
> + slave_config->src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
> + } else {
> + 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)as->phybase + SPI_TDR;
> + slave_config->src_addr = (dma_addr_t)as->phybase + SPI_RDR;
> + slave_config->src_maxburst = 1;
> + slave_config->dst_maxburst = 1;
> + slave_config->device_fc = false;
> +
> + slave_config->direction = DMA_MEM_TO_DEV;
> + if (dmaengine_slave_config(as->dma.chan_tx, slave_config)) {
> + dev_err(&as->pdev->dev,
> + "failed to configure tx dma channel\n");
> + err = -EINVAL;
> + }
> +
> + slave_config->direction = DMA_DEV_TO_MEM;
> + if (dmaengine_slave_config(as->dma.chan_rx, slave_config)) {
> + dev_err(&as->pdev->dev,
> + "failed to configure rx dma channel\n");
> + err = -EINVAL;
> + }
> +
> + return err;
> +}
> +
> +static bool filter(struct dma_chan *chan, void *slave)
> +{
> + struct at_dma_slave *sl = slave;
> +
> + if (sl->dma_dev == chan->device->dev) {
> + chan->private = sl;
> + return true;
> + } else {
> + return false;
> + }
> +}
> +
> +static int atmel_spi_configure_dma(struct atmel_spi *as)
> +{
> + struct at_dma_slave *sdata = &as->dma.dma_slave;
> + struct dma_slave_config slave_config;
> + int err;
> +
> + if (sdata && sdata->dma_dev) {
> + dma_cap_mask_t mask;
> +
> + /* Try to grab two DMA channels */
> + dma_cap_zero(mask);
> + dma_cap_set(DMA_SLAVE, mask);
> + as->dma.chan_tx = dma_request_channel(mask, filter, sdata);
> + if (as->dma.chan_tx)
> + as->dma.chan_rx =
> + dma_request_channel(mask, filter, sdata);
> + }
> + if (!as->dma.chan_rx || !as->dma.chan_tx) {
> + dev_err(&as->pdev->dev,
> + "DMA channel not available, SPI unable to use DMA\n");
> + err = -EBUSY;
> + goto error;
> + }
> +
> + err = atmel_spi_dma_slave_config(as, &slave_config, 8);
> + if (err)
> + goto error;
> +
> + dev_info(&as->pdev->dev,
> + "Using %s (tx) and %s (rx) for DMA transfers\n",
> + dma_chan_name(as->dma.chan_tx),
> + dma_chan_name(as->dma.chan_rx));
> + return 0;
> +error:
> + if (as->dma.chan_rx)
> + dma_release_channel(as->dma.chan_rx);
> + if (as->dma.chan_tx)
> + dma_release_channel(as->dma.chan_tx);
> + return err;
> +}
> +
> +static void atmel_spi_stop_dma(struct atmel_spi *as)
> +{
> + if (as->dma.chan_rx)
> + as->dma.chan_rx->device->device_control(as->dma.chan_rx,
> + DMA_TERMINATE_ALL, 0);
> + if (as->dma.chan_tx)
> + as->dma.chan_tx->device->device_control(as->dma.chan_tx,
> + DMA_TERMINATE_ALL, 0);
> +}
> +
> +static void atmel_spi_release_dma(struct atmel_spi *as)
> +{
> + if (as->dma.chan_rx)
> + dma_release_channel(as->dma.chan_rx);
> + if (as->dma.chan_tx)
> + dma_release_channel(as->dma.chan_tx);
> +}
> +
> +/* This function is called by the DMA driver from tasklet context */
> +static void dma_callback(void *data)
> +{
> + struct spi_master *master = data;
> + struct atmel_spi *as = spi_master_get_devdata(master);
> +
> + /* trigger SPI tasklet */
> + tasklet_schedule(&as->tasklet);
> +}
> +
> +/*
> + * Next transfer using PIO.
> + * lock is held, spi tasklet is blocked
> + */
> +static void atmel_spi_next_xfer_pio(struct spi_master *master,
> + struct spi_transfer *xfer)
> +{
> + struct atmel_spi *as = spi_master_get_devdata(master);
> +
> + dev_vdbg(master->dev.parent, "atmel_spi_next_xfer_pio\n");
> +
> + as->current_remaining_bytes = xfer->len;
> +
> + /* Make sure data is not remaining in RDR */
> + spi_readl(as, RDR);
> + while (spi_readl(as, SR) & SPI_BIT(RDRF)) {
> + spi_readl(as, RDR);
> + cpu_relax();
> + }
> +
> + if (xfer->tx_buf)
> + spi_writel(as, TDR, *(u8 *)(xfer->tx_buf));
> + else
> + spi_writel(as, TDR, 0);
> +
> + dev_dbg(master->dev.parent,
> + " start pio xfer %p: len %u tx %p rx %p\n",
> + xfer, xfer->len, xfer->tx_buf, xfer->rx_buf);
> +
> + /* Enable relevant interrupts */
> + spi_writel(as, IER, SPI_BIT(RDRF) | SPI_BIT(OVRES));
> +}
> +
> +/*
> + * Submit next transfer for DMA.
> + * lock is held, spi tasklet is blocked
> + */
> +static int atmel_spi_next_xfer_dma_submit(struct spi_master *master,
> + struct spi_transfer *xfer,
> + u32 *plen)
> +{
> + struct atmel_spi *as = spi_master_get_devdata(master);
> + struct dma_chan *rxchan = as->dma.chan_rx;
> + struct dma_chan *txchan = as->dma.chan_tx;
> + struct dma_async_tx_descriptor *rxdesc;
> + struct dma_async_tx_descriptor *txdesc;
> + struct dma_slave_config slave_config;
> + dma_cookie_t cookie;
> + u32 len = *plen;
> +
> + dev_vdbg(master->dev.parent, "atmel_spi_next_xfer_dma_submit\n");
> +
> + /* Check that the channels are available */
> + if (!rxchan || !txchan)
> + return -ENODEV;
> +
> + /* release lock for DMA operations */
> + atmel_spi_unlock(as);
> +
> + /* prepare the RX dma transfer */
> + sg_init_table(&as->dma.sgrx, 1);
> + if (xfer->rx_buf) {
> + as->dma.sgrx.dma_address = xfer->rx_dma + xfer->len - *plen;
> + } else {
> + as->dma.sgrx.dma_address = as->buffer_dma;
> + if (len > BUFFER_SIZE)
> + len = BUFFER_SIZE;
> + }
> +
> + /* prepare the TX dma transfer */
> + sg_init_table(&as->dma.sgtx, 1);
> + if (xfer->tx_buf) {
> + as->dma.sgtx.dma_address = xfer->tx_dma + xfer->len - *plen;
> + } else {
> + as->dma.sgtx.dma_address = as->buffer_dma;
> + if (len > BUFFER_SIZE)
> + len = BUFFER_SIZE;
> + memset(as->buffer, 0, len);
> + }
> +
> + sg_dma_len(&as->dma.sgtx) = len;
> + sg_dma_len(&as->dma.sgrx) = len;
> +
> + *plen = len;
> +
> + if (atmel_spi_dma_slave_config(as, &slave_config, 8))
> + goto err_exit;
> +
> + /* Send both scatterlists */
> + rxdesc = rxchan->device->device_prep_slave_sg(rxchan,
> + &as->dma.sgrx,
> + 1,
> + DMA_FROM_DEVICE,
> + DMA_PREP_INTERRUPT | DMA_CTRL_ACK,
> + NULL);
> + if (!rxdesc)
> + goto err_dma;
> +
> + txdesc = txchan->device->device_prep_slave_sg(txchan,
> + &as->dma.sgtx,
> + 1,
> + DMA_TO_DEVICE,
> + DMA_PREP_INTERRUPT | DMA_CTRL_ACK,
> + NULL);
> + if (!txdesc)
> + goto err_dma;
> +
> + dev_dbg(master->dev.parent,
> + " start dma xfer %p: len %u tx %p/%08x rx %p/%08x\n",
> + xfer, xfer->len, xfer->tx_buf, xfer->tx_dma,
> + xfer->rx_buf, xfer->rx_dma);
> +
> + /* Enable relevant interrupts */
> + spi_writel(as, IER, SPI_BIT(OVRES));
> +
> + /* Put the callback on the RX transfer only, that should finish last */
> + rxdesc->callback = dma_callback;
> + rxdesc->callback_param = master;
> +
> + /* Submit and fire RX and TX with TX last so we're ready to read! */
> + cookie = rxdesc->tx_submit(rxdesc);
> + if (dma_submit_error(cookie))
> + goto err_dma;
> + cookie = txdesc->tx_submit(txdesc);
> + if (dma_submit_error(cookie))
> + goto err_dma;
> + rxchan->device->device_issue_pending(rxchan);
> + txchan->device->device_issue_pending(txchan);
> +
> + /* take back lock */
> + atmel_spi_lock(as);
> + return 0;
> +
> +err_dma:
> + spi_writel(as, IDR, SPI_BIT(OVRES));
> + atmel_spi_stop_dma(as);
> +err_exit:
> + atmel_spi_lock(as);
> + return -ENOMEM;
> +}
> +
> static void atmel_spi_next_xfer_data(struct spi_master *master,
> struct spi_transfer *xfer,
> dma_addr_t *tx_dma,
> @@ -372,6 +663,7 @@ static void atmel_spi_next_xfer_data(struct spi_master *master,
> if (len > BUFFER_SIZE)
> len = BUFFER_SIZE;
> }
> +
> if (xfer->tx_buf)
> *tx_dma = xfer->tx_dma + xfer->len - *plen;
> else {
> @@ -387,10 +679,10 @@ static void atmel_spi_next_xfer_data(struct spi_master *master,
> }
>
> /*
> - * Submit next transfer for DMA.
> + * Submit next transfer for PDC.
> * lock is held, spi irq is blocked
> */
> -static void atmel_spi_next_xfer(struct spi_master *master,
> +static void atmel_spi_pdc_next_xfer(struct spi_master *master,
> struct spi_message *msg)
> {
> struct atmel_spi *as = spi_master_get_devdata(master);
> @@ -487,6 +779,48 @@ static void atmel_spi_next_xfer(struct spi_master *master,
> spi_writel(as, PTCR, SPI_BIT(TXTEN) | SPI_BIT(RXTEN));
> }
>
> +/*
> + * Choose way to submit next transfer and start it.
> + * lock is held, spi tasklet is blocked
> + */
> +static void atmel_spi_dma_next_xfer(struct spi_master *master,
> + struct spi_message *msg)
> +{
> + struct atmel_spi *as = spi_master_get_devdata(master);
> + struct spi_transfer *xfer;
> + u32 remaining, len;
> +
> + remaining = as->current_remaining_bytes;
> + if (remaining) {
> + xfer = as->current_transfer;
> + len = remaining;
> + } else {
> + if (!as->current_transfer)
> + xfer = list_entry(msg->transfers.next,
> + struct spi_transfer, transfer_list);
> + else
> + xfer = list_entry(
> + as->current_transfer->transfer_list.next,
> + struct spi_transfer, transfer_list);
> +
> + as->current_transfer = xfer;
> + len = xfer->len;
> + }
> +
> + if (atmel_spi_use_dma(as, xfer)) {
> + u32 total = len;
> + if (!atmel_spi_next_xfer_dma_submit(master, xfer, &len)) {
> + as->current_remaining_bytes = total - len;
> + return;
> + } else {
> + dev_err(&msg->spi->dev, "unable to use DMA, fallback to PIO\n");
> + }
> + }
> +
> + /* use PIO if error appened using DMA */
> + atmel_spi_next_xfer_pio(master, xfer);
> +}
> +
> static void atmel_spi_next_message(struct spi_master *master)
> {
> struct atmel_spi *as = spi_master_get_devdata(master);
> @@ -511,7 +845,10 @@ static void atmel_spi_next_message(struct spi_master *master)
> } else
> cs_activate(as, spi);
>
> - atmel_spi_next_xfer(master, msg);
> + if (as->use_pdc)
> + atmel_spi_pdc_next_xfer(master, msg);
> + else
> + atmel_spi_dma_next_xfer(master, msg);
> }
>
> /*
> @@ -564,6 +901,11 @@ static void atmel_spi_dma_unmap_xfer(struct spi_master *master,
> xfer->len, DMA_FROM_DEVICE);
> }
>
> +static void atmel_spi_disable_pdc_transfer(struct atmel_spi *as)
> +{
> + spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
> +}
> +
> static void
> atmel_spi_msg_done(struct spi_master *master, struct atmel_spi *as,
> struct spi_message *msg, int stay)
> @@ -589,14 +931,183 @@ atmel_spi_msg_done(struct spi_master *master, struct atmel_spi *as,
> as->done_status = 0;
>
> /* continue if needed */
> - if (list_empty(&as->queue) || as->stopping)
> - spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
> - else
> + if (list_empty(&as->queue) || as->stopping) {
> + if (as->use_pdc)
> + atmel_spi_disable_pdc_transfer(as);
> + } else {
> atmel_spi_next_message(master);
> + }
> +}
> +
> +/* Called from IRQ
> + * lock is held
> + *
> + * Must update "current_remaining_bytes" to keep track of data
> + * to transfer.
> + */
> +static void
> +atmel_spi_pump_pio_data(struct atmel_spi *as, struct spi_transfer *xfer)
> +{
> + u8 *txp;
> + u8 *rxp;
> + unsigned long xfer_pos = xfer->len - as->current_remaining_bytes;
> +
> + if (xfer->rx_buf) {
> + rxp = ((u8 *)xfer->rx_buf) + xfer_pos;
> + *rxp = spi_readl(as, RDR);
> + } else {
> + spi_readl(as, RDR);
> + }
> +
> + as->current_remaining_bytes--;
> +
> + if (as->current_remaining_bytes) {
> + if (xfer->tx_buf) {
> + txp = ((u8 *)xfer->tx_buf) + xfer_pos + 1;
> + spi_writel(as, TDR, *txp);
> + } else {
> + spi_writel(as, TDR, 0);
> + }
> + }
> +}
> +
> +/* Tasklet
> + * Called from DMA callback + pio transfer and overrun IRQ.
> + */
> +static void atmel_spi_tasklet_func(unsigned long data)
> +{
> + struct spi_master *master = (struct spi_master *)data;
> + struct atmel_spi *as = spi_master_get_devdata(master);
> + struct spi_message *msg;
> + struct spi_transfer *xfer;
> +
> + dev_vdbg(master->dev.parent, "atmel_spi_tasklet_func\n");
> +
> + atmel_spi_lock(as);
> +
> + xfer = as->current_transfer;
> +
> + if (xfer == NULL)
> + /* already been there */
> + goto tasklet_out;
> +
> + msg = list_entry(as->queue.next, struct spi_message, queue);
> +
> + if (as->current_remaining_bytes == 0) {
> + if (as->done_status < 0) {
> + /* error happened (overrun) */
> + if (atmel_spi_use_dma(as, xfer))
> + atmel_spi_stop_dma(as);
> + } else {
> + /* only update length if no error */
> + msg->actual_length += xfer->len;
> + }
> +
> + if (atmel_spi_use_dma(as, xfer))
> + if (!msg->is_dma_mapped)
> + atmel_spi_dma_unmap_xfer(master, xfer);
> +
> + if (xfer->delay_usecs)
> + udelay(xfer->delay_usecs);
> +
> + if (atmel_spi_xfer_is_last(msg, xfer) || as->done_status < 0) {
> + /* report completed (or erroneous) message */
> + atmel_spi_msg_done(master, as, msg, xfer->cs_change);
> + } else {
> + if (xfer->cs_change) {
> + cs_deactivate(as, msg->spi);
> + udelay(1);
> + cs_activate(as, msg->spi);
> + }
> +
> + /*
> + * Not done yet. Submit the next transfer.
> + *
> + * FIXME handle protocol options for xfer
> + */
> + atmel_spi_dma_next_xfer(master, msg);
> + }
> + } else {
> + /*
> + * Keep going, we still have data to send in
> + * the current transfer.
> + */
> + atmel_spi_dma_next_xfer(master, msg);
> + }
> +
> +tasklet_out:
> + atmel_spi_unlock(as);
> +}
> +
> +/* Interrupt
> + *
> + * No need for locking in this Interrupt handler: done_status is the
> + * only information modified. What we need is the update of this field
> + * before tasklet runs. This is ensured by using barrier.
> + */
> +static irqreturn_t
> +atmel_spi_pio_interrupt(int irq, void *dev_id)
> +{
> + struct spi_master *master = dev_id;
> + struct atmel_spi *as = spi_master_get_devdata(master);
> + u32 status, pending, imr;
> + struct spi_transfer *xfer;
> + int ret = IRQ_NONE;
> +
> + imr = spi_readl(as, IMR);
> + status = spi_readl(as, SR);
> + pending = status & imr;
> +
> + if (pending & SPI_BIT(OVRES)) {
> + ret = IRQ_HANDLED;
> + spi_writel(as, IDR, SPI_BIT(OVRES));
> + dev_warn(master->dev.parent, "overrun\n");
> +
> + /*
> + * When we get an overrun, we disregard the current
> + * transfer. Data will not be copied back from any
> + * bounce buffer and msg->actual_len will not be
> + * updated with the last xfer.
> + *
> + * We will also not process any remaning transfers in
> + * the message.
> + *
> + * All actions are done in tasklet with done_status indication
> + */
> + as->done_status = -EIO;
> + smp_wmb();
> +
> + /* Clear any overrun happening while cleaning up */
> + spi_readl(as, SR);
> +
> + tasklet_schedule(&as->tasklet);
> +
> + } else if (pending & SPI_BIT(RDRF)) {
> + atmel_spi_lock(as);
> +
> + if (as->current_remaining_bytes) {
> + ret = IRQ_HANDLED;
> + xfer = as->current_transfer;
> + atmel_spi_pump_pio_data(as, xfer);
> + if (!as->current_remaining_bytes) {
> + /* no more data to xfer, kick tasklet */
> + spi_writel(as, IDR, pending);
> + tasklet_schedule(&as->tasklet);
> + }
> + }
> +
> + atmel_spi_unlock(as);
> + } else {
> + WARN_ONCE(pending, "IRQ not handled, pending = %x\n", pending);
> + ret = IRQ_HANDLED;
> + spi_writel(as, IDR, pending);
> + }
> +
> + return ret;
> }
>
> static irqreturn_t
> -atmel_spi_interrupt(int irq, void *dev_id)
> +atmel_spi_pdc_interrupt(int irq, void *dev_id)
> {
> struct spi_master *master = dev_id;
> struct atmel_spi *as = spi_master_get_devdata(master);
> @@ -697,14 +1208,14 @@ atmel_spi_interrupt(int irq, void *dev_id)
> *
> * FIXME handle protocol options for xfer
> */
> - atmel_spi_next_xfer(master, msg);
> + atmel_spi_pdc_next_xfer(master, msg);
> }
> } else {
> /*
> * Keep going, we still have data to send in
> * the current transfer.
> */
> - atmel_spi_next_xfer(master, msg);
> + atmel_spi_pdc_next_xfer(master, msg);
> }
> }
>
> @@ -875,13 +1386,10 @@ static int atmel_spi_transfer(struct spi_device *spi, struct spi_message *msg)
>
> /*
> * DMA map early, for performance (empties dcache ASAP) and
> - * better fault reporting. This is a DMA-only driver.
> - *
> - * NOTE that if dma_unmap_single() ever starts to do work on
> - * platforms supported by this driver, we would need to clean
> - * up mappings for previously-mapped transfers.
> + * better fault reporting.
> */
> - if (!msg->is_dma_mapped) {
> + if ((!msg->is_dma_mapped) && (atmel_spi_use_dma(as, xfer)
> + || as->use_pdc)) {
> if (atmel_spi_dma_map_xfer(as, xfer) < 0)
> return -ENOMEM;
> }
> @@ -1000,6 +1508,7 @@ static int atmel_spi_probe(struct platform_device *pdev)
>
> spin_lock_init(&as->lock);
> INIT_LIST_HEAD(&as->queue);
> +
> as->pdev = pdev;
> as->regs = ioremap(regs->start, resource_size(regs));
> if (!as->regs)
> @@ -1010,8 +1519,28 @@ static int atmel_spi_probe(struct platform_device *pdev)
>
> atmel_get_caps(as);
>
> - ret = request_irq(irq, atmel_spi_interrupt, 0,
> - dev_name(&pdev->dev), master);
> + as->use_dma = false;
> + as->use_pdc = false;
> + if (as->caps.has_dma_support) {
> + if (atmel_spi_configure_dma(as) == 0)
> + as->use_dma = true;
> + } else {
> + as->use_pdc = true;
> + }
> +
> + if (as->caps.has_dma_support && !as->use_dma)
> + dev_info(&pdev->dev, "Atmel SPI Controller using PIO only\n");
> +
> + if (as->use_pdc) {
> + ret = request_irq(irq, atmel_spi_pdc_interrupt, 0,
> + dev_name(&pdev->dev), master);
> + } else {
> + tasklet_init(&as->tasklet, atmel_spi_tasklet_func,
> + (unsigned long)master);
> +
> + ret = request_irq(irq, atmel_spi_pio_interrupt, 0,
> + dev_name(&pdev->dev), master);
> + }
> if (ret)
> goto out_unmap_regs;
>
> @@ -1025,7 +1554,9 @@ static int atmel_spi_probe(struct platform_device *pdev)
> } else {
> spi_writel(as, MR, SPI_BIT(MSTR) | SPI_BIT(MODFDIS));
> }
> - spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
> +
> + if (as->use_pdc)
> + spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
> spi_writel(as, CR, SPI_BIT(SPIEN));
>
> /* go! */
> @@ -1034,11 +1565,14 @@ static int atmel_spi_probe(struct platform_device *pdev)
>
> ret = spi_register_master(master);
> if (ret)
> - goto out_reset_hw;
> + goto out_free_dma;
>
> return 0;
>
> -out_reset_hw:
> +out_free_dma:
> + if (as->use_dma)
> + atmel_spi_release_dma(as);
> +
> spi_writel(as, CR, SPI_BIT(SWRST));
> spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
> clk_disable(clk);
> @@ -1046,6 +1580,8 @@ out_reset_hw:
> out_unmap_regs:
> iounmap(as->regs);
> out_free_buffer:
> + if (!as->use_pdc)
> + tasklet_kill(&as->tasklet);
> dma_free_coherent(&pdev->dev, BUFFER_SIZE, as->buffer,
> as->buffer_dma);
> out_free:
> @@ -1064,6 +1600,11 @@ static int atmel_spi_remove(struct platform_device *pdev)
> /* reset the hardware and block queue progress */
> spin_lock_irq(&as->lock);
> as->stopping = 1;
> + if (as->use_dma) {
> + atmel_spi_stop_dma(as);
> + atmel_spi_release_dma(as);
> + }
> +
> spi_writel(as, CR, SPI_BIT(SWRST));
> spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
> spi_readl(as, SR);
> @@ -1072,13 +1613,17 @@ static int atmel_spi_remove(struct platform_device *pdev)
> /* Terminate remaining queued transfers */
> list_for_each_entry(msg, &as->queue, queue) {
> list_for_each_entry(xfer, &msg->transfers, transfer_list) {
> - if (!msg->is_dma_mapped)
> + if (!msg->is_dma_mapped
> + && (atmel_spi_use_dma(as, xfer)
> + || as->use_pdc))
> atmel_spi_dma_unmap_xfer(master, xfer);
> }
> msg->status = -ESHUTDOWN;
> msg->complete(msg->context);
> }
>
> + if (!as->use_pdc)
> + tasklet_kill(&as->tasklet);
> dma_free_coherent(&pdev->dev, BUFFER_SIZE, as->buffer,
> as->buffer_dma);
>
> --
> 1.7.9.5
>
As I did some work on that one:
Signed-off-by: Richard Genoud <richard.genoud@...il.com>
BUT, there's one thing not working (at least for me !):
With DMA enabled, using spidev.
if we use the ioctl SPI_IOC_MESSAGE(x) (tested with x=3):
#define SMALL 2
#define BIG 120
#define NB 3
struct spi_ioc_transfer xfer[NB];
char buffer[BIG];
char rx_header[SMALL];
char rx_footer[SMALL];
char tx_header[SMALL];
char tx_footer[SMALL];
xfer[0].tx_buf = (unsigned long)&tx_header;
xfer[0].rx_buf = (unsigned long)&rx_header;
xfer[0].len = SMALL;
xfer[1].tx_buf = (unsigned long)buffer;
xfer[1].rx_buf = (unsigned long)buffer;
xfer[1].len = BIG;
xfer[2].tx_buf = (unsigned long)&tx_footer;
xfer[2].rx_buf = (unsigned long)&rx_footer;
xfer[2].len = SMALL
ioctl(fd, SPI_IOC_MESSAGE(NB), xfer);
In this use case, the buffer received contains weird stuff *sometimes*
(header corrupted for example).
BUT if I set
+#define DMA_MIN_BYTES 1
instead of:
+#define DMA_MIN_BYTES 16
Everything works fine.
So I suggest for now:
+/*
+ * FIXME: alternating DMA and PIO transfert (with SPI_IOC_MESSAGE() for
+ * instance), seems to corrupt data.
+ */
+#define DMA_MIN_BYTES 1
With that change:
On sam9g35 with DMA and PIO (3.9-rc5 + device tree patches)
Tested-by: Richard Genoud <richard.genoud@...il.com>
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