diff options
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/spi-bcm2835.c | 96 |
1 files changed, 13 insertions, 83 deletions
diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c index 43c6ca535800..99797bbc65ae 100644 --- a/drivers/spi/spi-bcm2835.c +++ b/drivers/spi/spi-bcm2835.c @@ -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; |