hwrng: imx-rngc - check the rng type

Read the rng type and hardware revision during probe. Fail the probe
operation if the type is not one of rngc or rngb.
(There's also an rnga type, which needs a different driver.)

Display the type and revision in a debug print if probe was successful.

Reviewed-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/char/hw_random/imx-rngc.c b/drivers/char/hw_random/imx-rngc.c
index 92e93ab..50a8923 100644 (file)
--- a/drivers/char/hw_random/imx-rngc.c
+++ b/drivers/char/hw_random/imx-rngc.c
@@ -18,12 +18,22 @@
 #include <linux/completion.h>
 #include <linux/io.h>
 
+#define RNGC_VER_ID                    0x0000
 #define RNGC_COMMAND                   0x0004
 #define RNGC_CONTROL                   0x0008
 #define RNGC_STATUS                    0x000C
 #define RNGC_ERROR                     0x0010
 #define RNGC_FIFO                      0x0014
 
+/* the fields in the ver id register */
+#define RNGC_TYPE_SHIFT                28
+#define RNGC_VER_MAJ_SHIFT             8
+
+/* the rng_type field */
+#define RNGC_TYPE_RNGB                 0x1
+#define RNGC_TYPE_RNGC                 0x2
+
+
 #define RNGC_CMD_CLR_ERR               0x00000020
 #define RNGC_CMD_CLR_INT               0x00000010
 #define RNGC_CMD_SEED                  0x00000002
@@ -212,6 +222,8 @@ static int imx_rngc_probe(struct platform_device *pdev)
        struct imx_rngc *rngc;
        int ret;
        int irq;
+       u32 ver_id;
+       u8  rng_type;
 
        rngc = devm_kzalloc(&pdev->dev, sizeof(*rngc), GFP_KERNEL);
        if (!rngc)
@@ -237,6 +249,17 @@ static int imx_rngc_probe(struct platform_device *pdev)
        if (ret)
                return ret;
 
+       ver_id = readl(rngc->base + RNGC_VER_ID);
+       rng_type = ver_id >> RNGC_TYPE_SHIFT;
+       /*
+        * This driver supports only RNGC and RNGB. (There's a different
+        * driver for RNGA.)
+        */
+       if (rng_type != RNGC_TYPE_RNGC && rng_type != RNGC_TYPE_RNGB) {
+               ret = -ENODEV;
+               goto err;
+       }
+
        ret = devm_request_irq(&pdev->dev,
                        irq, imx_rngc_irq, 0, pdev->name, (void *)rngc);
        if (ret) {
@@ -269,7 +292,10 @@ static int imx_rngc_probe(struct platform_device *pdev)
                goto err;
        }
 
-       dev_info(&pdev->dev, "Freescale RNGC registered.\n");
+       dev_info(&pdev->dev,
+               "Freescale RNG%c registered (HW revision %d.%02d)\n",
+               rng_type == RNGC_TYPE_RNGB ? 'B' : 'C',
+               (ver_id >> RNGC_VER_MAJ_SHIFT) & 0xff, ver_id & 0xff);
        return 0;
 
 err: