spi: spi_bfin, don't bypass spi framework

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@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/spi/spi_bfin5xx.c

@@ -998,6 +998,18 @@ 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 manages\n");
+			return -EINVAL;
+		}
+
 		chip->enable_dma = chip_info->enable_dma != 0
 		    && drv_data->master_info->enable_dma;
 		chip->ctl_reg = chip_info->ctl_reg;