@@ -20,7 +20,6 @@
* GNU General Public License for more details.
*/
-#include <asm/page.h>
#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/delay.h>
@@ -108,7 +107,7 @@ struct bcm2835_spi {
int rx_len;
int tx_prologue;
int rx_prologue;
- bool tx_spillover;
+ unsigned int tx_spillover;
unsigned int dma_pending;
};
@@ -155,21 +154,20 @@ static inline void bcm2835_wr_fifo(struct bcm2835_spi *bs)
* The caller must ensure that @bs->rx_len is greater than or equal to @count,
* that the RX FIFO contains at least @count bytes and that the DMA Enable flag
* in the CS register is set (such that a read from the FIFO register receives
- * 32-bit instead of just 8-bit).
+ * 32-bit instead of just 8-bit). Moreover @bs->rx_buf must not be %NULL.
*/
static inline void bcm2835_rd_fifo_count(struct bcm2835_spi *bs, int count)
{
u32 val;
+ int len;
bs->rx_len -= count;
while (count > 0) {
val = bcm2835_rd(bs, BCM2835_SPI_FIFO);
- if (bs->rx_buf) {
- int len = min(count, 4);
- memcpy(bs->rx_buf, &val, len);
- bs->rx_buf += len;
- }
+ len = min(count, 4);
+ memcpy(bs->rx_buf, &val, len);
+ bs->rx_buf += len;
count -= 4;
}
}
@@ -187,12 +185,13 @@ static inline void bcm2835_rd_fifo_count(struct bcm2835_spi *bs, int count)
static inline void bcm2835_wr_fifo_count(struct bcm2835_spi *bs, int count)
{
u32 val;
+ int len;
bs->tx_len -= count;
while (count > 0) {
if (bs->tx_buf) {
- int len = min(count, 4);
+ len = min(count, 4);
memcpy(&val, bs->tx_buf, len);
bs->tx_buf += len;
} else {
@@ -206,6 +205,10 @@ static inline void bcm2835_wr_fifo_count(struct bcm2835_spi *bs, int count)
/**
* bcm2835_wait_tx_fifo_empty() - busy-wait for TX FIFO to empty
* @bs: BCM2835 SPI controller
+ *
+ * The caller must ensure that the RX FIFO can accommodate as many bytes
+ * as have been written to the TX FIFO: Transmission is halted once the
+ * RX FIFO is full, causing this function to spin forever.
*/
static inline void bcm2835_wait_tx_fifo_empty(struct bcm2835_spi *bs)
{
@@ -379,11 +382,12 @@ static void bcm2835_spi_transfer_prologue(struct spi_master *master,
bcm2835_rd_fifo_count(bs, bs->rx_prologue);
bcm2835_spi_reset_hw(master);
- dma_sync_sg_for_device(master->dma_rx->device->dev,
- tfr->rx_sg.sgl, 1, DMA_FROM_DEVICE);
+ dma_sync_single_for_device(master->dma_rx->device->dev,
+ sg_dma_address(&tfr->rx_sg.sgl[0]),
+ bs->rx_prologue, DMA_FROM_DEVICE);
- tfr->rx_sg.sgl[0].dma_address += bs->rx_prologue;
- tfr->rx_sg.sgl[0].length -= bs->rx_prologue;
+ sg_dma_address(&tfr->rx_sg.sgl[0]) += bs->rx_prologue;
+ sg_dma_len(&tfr->rx_sg.sgl[0]) -= bs->rx_prologue;
}
/*
@@ -401,12 +405,12 @@ static void bcm2835_spi_transfer_prologue(struct spi_master *master,
}
if (likely(!bs->tx_spillover)) {
- tfr->tx_sg.sgl[0].dma_address += bs->tx_prologue;
- tfr->tx_sg.sgl[0].length -= bs->tx_prologue;
+ sg_dma_address(&tfr->tx_sg.sgl[0]) += bs->tx_prologue;
+ sg_dma_len(&tfr->tx_sg.sgl[0]) -= bs->tx_prologue;
} else {
- tfr->tx_sg.sgl[0].length = 0;
- tfr->tx_sg.sgl[1].dma_address += 4;
- tfr->tx_sg.sgl[1].length -= 4;
+ sg_dma_len(&tfr->tx_sg.sgl[0]) = 0;
+ sg_dma_address(&tfr->tx_sg.sgl[1]) += 4;
+ sg_dma_len(&tfr->tx_sg.sgl[1]) -= 4;
}
}
@@ -426,17 +430,17 @@ static void bcm2835_spi_undo_prologue(struct bcm2835_spi *bs)
return;
if (bs->rx_prologue) {
- tfr->rx_sg.sgl[0].dma_address -= bs->rx_prologue;
- tfr->rx_sg.sgl[0].length += bs->rx_prologue;
+ sg_dma_address(&tfr->rx_sg.sgl[0]) -= bs->rx_prologue;
+ sg_dma_len(&tfr->rx_sg.sgl[0]) += bs->rx_prologue;
}
if (likely(!bs->tx_spillover)) {
- tfr->tx_sg.sgl[0].dma_address -= bs->tx_prologue;
- tfr->tx_sg.sgl[0].length += bs->tx_prologue;
+ sg_dma_address(&tfr->tx_sg.sgl[0]) -= bs->tx_prologue;
+ sg_dma_len(&tfr->tx_sg.sgl[0]) += bs->tx_prologue;
} else {
- tfr->tx_sg.sgl[0].length = bs->tx_prologue - 4;
- tfr->tx_sg.sgl[1].dma_address -= 4;
- tfr->tx_sg.sgl[1].length += 4;
+ sg_dma_len(&tfr->tx_sg.sgl[0]) = bs->tx_prologue - 4;
+ sg_dma_address(&tfr->tx_sg.sgl[1]) -= 4;
+ sg_dma_len(&tfr->tx_sg.sgl[1]) += 4;
}
}
Commit 3bd7f6589f67 ("spi: bcm2835: Overcome sglist entry length limitation") was unfortunately merged even though submission of a refined version was imminent. Apply those refinements as an amendment: * Drop no longer needed #include <asm/page.h>. The lines requiring its inclusion were removed by the commit. * Change type of tx_spillover flag from bool to unsigned int for consistency with dma_pending flag and pursuant to Linus' dictum: https://lkml.org/lkml/2017/11/21/384 * In bcm2835_rd_fifo_count() do not check for bs->rx_buf != NULL. The function will never be called if that's the case. * Amend kerneldoc of bcm2835_wait_tx_fifo_empty() to prevent its use in situations where the function might spin forever. (In response to a review comment by Stefan Wahren.) * Sync only the cacheline containing the RX prologue back to memory, not the full first sglist entry. * Use sg_dma_address() and sg_dma_len() instead of referencing the sglist entry members directly. Seems to be the more common syntax in the tree, even for lvalues. Signed-off-by: Lukas Wunner <lukas@wunner.de> Cc: Frank Pavlic <f.pavlic@kunbus.de> Cc: Martin Sperl <kernel@martin.sperl.org> Cc: Noralf Trønnes <noralf@tronnes.org> --- drivers/spi/spi-bcm2835.c | 54 +++++++++++++++++++++------------------ 1 file changed, 29 insertions(+), 25 deletions(-)