From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-pd0-x22b.google.com ([2607:f8b0:400e:c02::22b]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Y6Kvf-00023q-W5 for barebox@lists.infradead.org; Wed, 31 Dec 2014 15:11:20 +0000 Received: by mail-pd0-f171.google.com with SMTP id y13so21023977pdi.16 for ; Wed, 31 Dec 2014 07:10:59 -0800 (PST) From: Andrey Smirnov Date: Wed, 31 Dec 2014 07:10:55 -0800 Message-Id: <1420038655-8856-1-git-send-email-andrew.smirnov@gmail.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: [PATCH] i.MX: SPI: Respect SPI_LSB_FIRST flag in mode settings To: barebox@lists.infradead.org Cc: Andrey Smirnov Add code to support SPI transfers that have data shifted out least significant bit first. This is useful in many cases, but specifically it is needed for drivers/firmware/altera_serial.c to work on i.MX platform. Signed-off-by: Andrey Smirnov --- drivers/spi/imx_spi.c | 50 ++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 44 insertions(+), 6 deletions(-) diff --git a/drivers/spi/imx_spi.c b/drivers/spi/imx_spi.c index 3146339..efbbb08 100644 --- a/drivers/spi/imx_spi.c +++ b/drivers/spi/imx_spi.c @@ -137,6 +137,25 @@ static int imx_spi_setup(struct spi_device *spi) return 0; } +static unsigned int imx_spi_maybe_reverse_bits(struct spi_device *spi, unsigned int word) +{ + unsigned int result = word; + + if (spi->mode & SPI_LSB_FIRST) { + size_t bits_left = spi->bits_per_word - 1; + + for (word >>= 1; word; word >>= 1) { + result <<= 1; + result |= word & 1; + bits_left--; + } + + result <<= bits_left; + } + + return result; +} + static unsigned int cspi_0_0_xchg_single(struct imx_spi *imx, unsigned int data) { void __iomem *base = imx->regs; @@ -386,6 +405,7 @@ static void imx_spi_do_transfer(struct spi_device *spi, struct spi_transfer *t) { struct imx_spi *imx = container_of(spi->master, struct imx_spi, master); unsigned i; + u32 tx_val; if (spi->bits_per_word <= 8) { const u8 *tx_buf = t->tx_buf; @@ -393,9 +413,15 @@ static void imx_spi_do_transfer(struct spi_device *spi, struct spi_transfer *t) u8 rx_val; for (i = 0; i < t->len; i++) { - rx_val = imx->xchg_single(imx, tx_buf ? tx_buf[i] : 0); + if (tx_buf) + tx_val = imx_spi_maybe_reverse_bits(spi, tx_buf[i]); + else + tx_val = 0; + + rx_val = imx->xchg_single(imx, tx_val); + if (rx_buf) - rx_buf[i] = rx_val; + rx_buf[i] = (u8)imx_spi_maybe_reverse_bits(spi, rx_val); } } else if (spi->bits_per_word <= 16) { const u16 *tx_buf = t->tx_buf; @@ -403,9 +429,15 @@ static void imx_spi_do_transfer(struct spi_device *spi, struct spi_transfer *t) u16 rx_val; for (i = 0; i < t->len >> 1; i++) { - rx_val = imx->xchg_single(imx, tx_buf ? tx_buf[i] : 0); + if (tx_buf) + tx_val = imx_spi_maybe_reverse_bits(spi, tx_buf[i]); + else + tx_val = 0; + + rx_val = imx->xchg_single(imx, tx_val); + if (rx_buf) - rx_buf[i] = rx_val; + rx_buf[i] = (u16)imx_spi_maybe_reverse_bits(spi, rx_val); } } else if (spi->bits_per_word <= 32) { const u32 *tx_buf = t->tx_buf; @@ -413,9 +445,15 @@ static void imx_spi_do_transfer(struct spi_device *spi, struct spi_transfer *t) u32 rx_val; for (i = 0; i < t->len >> 2; i++) { - rx_val = imx->xchg_single(imx, tx_buf ? tx_buf[i] : 0); + if (tx_buf) + tx_val = imx_spi_maybe_reverse_bits(spi, tx_buf[i]); + else + tx_val = 0; + + rx_val = imx->xchg_single(imx, tx_val); + if (rx_buf) - rx_buf[i] = rx_val; + rx_buf[i] = imx_spi_maybe_reverse_bits(spi, rx_val); } } } -- 2.1.0 _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox