From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gregory CLEMENT Date: Tue, 09 Oct 2018 14:11:38 +0200 Subject: [U-Boot] [PATCH] DW SPI: Allow to overload the management of the external CS In-Reply-To: (Daniel Schwierzeck's message of "Wed, 26 Sep 2018 21:55:07 +0200") References: <20180925131731.20933-1-gregory.clement@bootlin.com> Message-ID: <87sh1fiakl.fsf@bootlin.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Daniel, On mer., sept. 26 2018, Daniel Schwierzeck wrote: > On 25.09.2018 15:17, Gregory CLEMENT wrote: >> On some platforms, as the Ocelot ones, when wanting to control the CS >> through software, it is not possible to do it through the GPIO >> controller. Indeed, this signal is managed through a dedicated range of >> registers inside the SoC.. > > and why did you add a spi-bitbang-gpio driver? Because the DW SPI is not available on Luton, so for Luton we can only use a spi-bitbang-gpio driver which is very slow. Gregory > >> >> By declaring the external_cs_manage function as weak, it is possible to >> manage the CS at platform level and then using the appropriate registers. >> >> Signed-off-by: Gregory CLEMENT >> --- >> drivers/spi/designware_spi.c | 8 +++++++- >> 1 file changed, 7 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/spi/designware_spi.c b/drivers/spi/designware_spi.c >> index d8b73ea326..fe6e753bff 100644 >> --- a/drivers/spi/designware_spi.c >> +++ b/drivers/spi/designware_spi.c >> @@ -334,7 +334,13 @@ static int poll_transfer(struct dw_spi_priv *priv) >> return 0; >> } >> >> -static void external_cs_manage(struct udevice *dev, bool on) >> +/* >> + * We define external_cs_manage function as 'weak' as some targets >> + * (like OCELOT) don't control the external CS pin using a GPIO >> + * controller. These SoCs use specific registers to controll by >> + * software the SPI pins (and especially the CS). >> + */ >> +__weak void external_cs_manage(struct udevice *dev, bool on) >> { >> #if defined(CONFIG_DM_GPIO) && !defined(CONFIG_SPL_BUILD) >> struct dw_spi_priv *priv = dev_get_priv(dev->parent); >> > > -- > - Daniel > -- Gregory Clement, Bootlin Embedded Linux and Kernel engineering http://bootlin.com