spi/spi_s3c64xx: Make probe more robust against missing board config

The S3C64xx SPI driver requires the machine to call s3c64xx_spi_set_info()
to select a few options, including the clock to use for the SPI controller.
If this is not done then a NULL will be passed as the clock name for
clk_get(), causing an obscure crash. Guard against this and other missing
configuration by validating that the clock name has been filled in in
the platform data that ets passed in.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

drivers/spi/spi_s3c64xx.c

@@ -919,6 +919,13 @@ static int __init s3c64xx_spi_probe(struct platform_device *pdev)
 		return -ENODEV;
 	}
 
+	sci = pdev->dev.platform_data;
+	if (!sci->src_clk_name) {
+		dev_err(&pdev->dev,
+			"Board init must call s3c64xx_spi_set_info()\n");
+		return -EINVAL;
+	}
+
 	/* Check for availability of necessary resource */
 
 	dmatx_res = platform_get_resource(pdev, IORESOURCE_DMA, 0);
@@ -946,8 +953,6 @@ static int __init s3c64xx_spi_probe(struct platform_device *pdev)
 		return -ENOMEM;
 	}
 
-	sci = pdev->dev.platform_data;
-
 	platform_set_drvdata(pdev, master);
 
 	sdd = spi_master_get_devdata(master);