[PATCH 4/9] Blackfin SPI driver: prevent people from setting bits in ctl_reg

[Bryan Wu <bryan.wu-OyLXuOCK7orQT0dZR+AlfA@public.gmane.org>]

From: Mike Frysinger <michael.frysinger-OyLXuOCK7orQT0dZR+AlfA@public.gmane.org>

Prevent people from setting bits in ctl_reg that the SPI
framework already handles, hopefully we can one day drop
ctl_reg completely

Signed-off-by: Mike Frysinger <michael.frysinger-OyLXuOCK7orQT0dZR+AlfA@public.gmane.org>
Signed-off-by: Bryan Wu <bryan.wu-OyLXuOCK7orQT0dZR+AlfA@public.gmane.org>
---
 drivers/spi/spi_bfin5xx.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/drivers/spi/spi_bfin5xx.c b/drivers/spi/spi_bfin5xx.c
index 7093065..1a83656 100644
--- a/drivers/spi/spi_bfin5xx.c
+++ b/drivers/spi/spi_bfin5xx.c
@@ -996,6 +996,16 @@ static int setup(struct spi_device *spi)
 
 	/* chip_info isn't always needed */
 	if (chip_info) {
+		/* Make sure people stop trying to set fields via ctl_reg when they
+		 * should actually be using common SPI framework.  Currently we let
+		 * through: WOM EMISO PSSE GM SZ TIMOD.  Not sure if a user actually
+		 * needs/uses any of these, but let's assume (for now) they do.
+		 */
+		if (chip_info->ctl_reg & (SPE | MSTR | CPOL | CPHA | LSBF | SIZE)) {
+			dev_err(&spi->dev, "do not set bits in ctl_reg that the SPI framework provides\n");
+			return -EINVAL;
+		}
+
 		chip->enable_dma = chip_info->enable_dma != 0
 		    && drv_data->master_info->enable_dma;
 		chip->ctl_reg = chip_info->ctl_reg;
-- 
1.5.3.4

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