From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:6f8:1178:4:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Y841J-00059u-4g for barebox@lists.infradead.org; Mon, 05 Jan 2015 09:32:17 +0000 Date: Mon, 5 Jan 2015 10:31:54 +0100 From: Sascha Hauer Message-ID: <20150105093154.GE30369@pengutronix.de> References: <1420038655-8856-1-git-send-email-andrew.smirnov@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1420038655-8856-1-git-send-email-andrew.smirnov@gmail.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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: Re: [PATCH] i.MX: SPI: Respect SPI_LSB_FIRST flag in mode settings To: Andrey Smirnov Cc: barebox@lists.infradead.org Hi Andrey, On Wed, Dec 31, 2014 at 07:10:55AM -0800, Andrey Smirnov wrote: > 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); > + Better introduce a imx_xchg_single which does the necessary bit reversing and calls imx->xchg_single. This avoids duplicating the code for all three bits_per_word settings. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox