From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Ungerer Subject: [PATCHv2 1/2] spi: imx: fix use of native chip-selects with devicetree Date: Tue, 21 Mar 2017 22:43:24 +1000 Message-ID: <1490100205-31309-2-git-send-email-gerg@linux-m68k.org> References: <1490100205-31309-1-git-send-email-gerg@linux-m68k.org> Cc: shawnguo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, kernel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org, fabio.estevam-3arQi8VN3Tc@public.gmane.org, Greg Ungerer To: linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Return-path: In-Reply-To: <1490100205-31309-1-git-send-email-gerg-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org> Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: The commonly used mechanism of specifying the hardware or native chip-select on an SPI device in devicetree (that is "cs-gpios = <0>") does not result in the native chip-select being configured for use. So external SPI devices that require use of the native chip-select will not work. You can successfully specify native chip-selects if using a platform setup by specifying the cs-gpio as negative offset by 32. And that works correctly. You cannot use the same method in devicetree. The logic in the spi-imx.c driver during probe uses core spi function of_spi_register_master() in spi.c to parse the "cs-gpios" devicetree tag. For valid GPIO values that will be recorded for use, all other entries in the cs_gpios list will be set to -ENOENT. So entries like "<0>" will be set to -ENOENT in the cs_gpios list. When the SPI device registers are setup the code will use the GPIO listed in the cs_gpios list for the desired chip-select. If the cs_gpio is less then 0 then it is intended to be for a native chip-select, and its cs_gpio value is added to 32 to get the chipselect number to use. Problem is that with devicetree this can only ever be -ENOENT (which is -2), and that alone results in an invalid chip-select number. But also doesn't allow selection of the native chip-select at all. To fix, if the cs_gpio specified for this spi device is not a valid GPIO then use the "chip_select" (that is the native chip-select number) for hardware setup. Signed-off-by: Greg Ungerer --- drivers/spi/spi-imx.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) v2: added documentation to patch set diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c index 9a7c62f..dbb482c 100644 --- a/drivers/spi/spi-imx.c +++ b/drivers/spi/spi-imx.c @@ -516,8 +516,8 @@ static int mx31_config(struct spi_device *spi, struct spi_imx_config *config) reg |= MX31_CSPICTRL_POL; if (spi->mode & SPI_CS_HIGH) reg |= MX31_CSPICTRL_SSPOL; - if (spi->cs_gpio < 0) - reg |= (spi->cs_gpio + 32) << + if (!gpio_is_valid(spi->cs_gpio)) + reg |= (spi->chip_select) << (is_imx35_cspi(spi_imx) ? MX35_CSPICTRL_CS_SHIFT : MX31_CSPICTRL_CS_SHIFT); @@ -608,8 +608,8 @@ static int mx21_config(struct spi_device *spi, struct spi_imx_config *config) reg |= MX21_CSPICTRL_POL; if (spi->mode & SPI_CS_HIGH) reg |= MX21_CSPICTRL_SSPOL; - if (spi->cs_gpio < 0) - reg |= (spi->cs_gpio + 32) << MX21_CSPICTRL_CS_SHIFT; + if (!gpio_is_valid(spi->cs_gpio)) + reg |= spi->chip_select << MX21_CSPICTRL_CS_SHIFT; writel(reg, spi_imx->base + MXC_CSPICTRL); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html