@@ -172,28 +172,16 @@ static int bcm2835_spi_transfer_one_irq(struct spi_master *master,
{
struct bcm2835_spi *bs = spi_master_get_devdata(master);
- /* fill in fifo if we have gpio-cs
- * note that there have been rare events where the native-CS
- * flapped for <1us which may change the behaviour
- * with gpio-cs this does not happen, so it is implemented
- * only for this case
- */
- if (gpio_is_valid(spi->cs_gpio)) {
- /* enable HW block, but without interrupts enabled
- * this would triggern an immediate interrupt
- */
- bcm2835_wr(bs, BCM2835_SPI_CS,
- cs | BCM2835_SPI_CS_TA);
- /* fill in tx fifo as much as possible */
- bcm2835_wr_fifo(bs);
- }
-
/*
- * Enable the HW block. This will immediately trigger a DONE (TX
- * empty) interrupt, upon which we will fill the TX FIFO with the
- * first TX bytes. Pre-filling the TX FIFO here to avoid the
- * interrupt doesn't work:-(
+ * Enable HW block, but with interrupts still disabled.
+ * Otherwise the empty TX FIFO would immediately trigger an interrupt.
*/
+ bcm2835_wr(bs, BCM2835_SPI_CS, cs | BCM2835_SPI_CS_TA);
+
+ /* fill TX FIFO as much as possible */
+ bcm2835_wr_fifo(bs);
+
+ /* enable interrupts */
cs |= BCM2835_SPI_CS_INTR | BCM2835_SPI_CS_INTD | BCM2835_SPI_CS_TA;
bcm2835_wr(bs, BCM2835_SPI_CS, cs);
@@ -356,10 +344,6 @@ static bool bcm2835_spi_can_dma(struct spi_master *master,
struct spi_device *spi,
struct spi_transfer *tfr)
{
- /* only run for gpio_cs */
- if (!gpio_is_valid(spi->cs_gpio))
- return false;
-
/* we start DMA efforts only on bigger transfers */
if (tfr->len < BCM2835_SPI_DMA_MIN_LENGTH)
return false;
@@ -559,12 +543,12 @@ static int bcm2835_spi_transfer_one(struct spi_master *master,
else
cs &= ~BCM2835_SPI_CS_REN;
- /* for gpio_cs set dummy CS so that no HW-CS get changed
- * we can not run this in bcm2835_spi_set_cs, as it does
- * not get called for cs_gpio cases, so we need to do it here
+ /*
+ * The driver always uses software-controlled GPIO Chip Select.
+ * Set the hardware-controlled native Chip Select to an invalid
+ * value to prevent it from interfering.
*/
- if (gpio_is_valid(spi->cs_gpio) || (spi->mode & SPI_NO_CS))
- cs |= BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01;
+ cs |= BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01;
/* set transmit buffers and length */
bs->tx_buf = tfr->tx_buf;
@@ -624,59 +608,6 @@ static void bcm2835_spi_handle_err(struct spi_master *master,
bcm2835_spi_reset_hw(master);
}
-static void bcm2835_spi_set_cs(struct spi_device *spi, bool gpio_level)
-{
- /*
- * we can assume that we are "native" as per spi_set_cs
- * calling us ONLY when cs_gpio is not set
- * we can also assume that we are CS < 3 as per bcm2835_spi_setup
- * we would not get called because of error handling there.
- * the level passed is the electrical level not enabled/disabled
- * so it has to get translated back to enable/disable
- * see spi_set_cs in spi.c for the implementation
- */
-
- struct spi_master *master = spi->master;
- struct bcm2835_spi *bs = spi_master_get_devdata(master);
- u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
- bool enable;
-
- /* calculate the enable flag from the passed gpio_level */
- enable = (spi->mode & SPI_CS_HIGH) ? gpio_level : !gpio_level;
-
- /* set flags for "reverse" polarity in the registers */
- if (spi->mode & SPI_CS_HIGH) {
- /* set the correct CS-bits */
- cs |= BCM2835_SPI_CS_CSPOL;
- cs |= BCM2835_SPI_CS_CSPOL0 << spi->chip_select;
- } else {
- /* clean the CS-bits */
- cs &= ~BCM2835_SPI_CS_CSPOL;
- cs &= ~(BCM2835_SPI_CS_CSPOL0 << spi->chip_select);
- }
-
- /* select the correct chip_select depending on disabled/enabled */
- if (enable) {
- /* set cs correctly */
- if (spi->mode & SPI_NO_CS) {
- /* use the "undefined" chip-select */
- cs |= BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01;
- } else {
- /* set the chip select */
- cs &= ~(BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01);
- cs |= spi->chip_select;
- }
- } else {
- /* disable CSPOL which puts HW-CS into deselected state */
- cs &= ~BCM2835_SPI_CS_CSPOL;
- /* use the "undefined" chip-select as precaution */
- cs |= BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01;
- }
-
- /* finally set the calculated flags in SPI_CS */
- bcm2835_wr(bs, BCM2835_SPI_CS, cs);
-}
-
static int chip_match_name(struct gpio_chip *chip, void *data)
{
return !strcmp(chip->label, data);
@@ -748,7 +679,6 @@ static int bcm2835_spi_probe(struct platform_device *pdev)
master->bits_per_word_mask = SPI_BPW_MASK(8);
master->num_chipselect = 3;
master->setup = bcm2835_spi_setup;
- master->set_cs = bcm2835_spi_set_cs;
master->transfer_one = bcm2835_spi_transfer_one;
master->handle_err = bcm2835_spi_handle_err;
master->prepare_message = bcm2835_spi_prepare_message;
Commit a30a555d7435 ("spi: bcm2835: transform native-cs to gpio-cs on first spi_setup") disabled the use of hardware-controlled native Chip Select in favour of software-controlled GPIO Chip Select but left code to support the former untouched. Remove it to simplify the driver and ease the addition of new features and further optimizations. Signed-off-by: Lukas Wunner <lukas@wunner.de> Cc: Mathias Duckeck <m.duckeck@kunbus.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 | 96 ++++++--------------------------------- 1 file changed, 13 insertions(+), 83 deletions(-)