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SubjectRe: [PATCH 5/6] hwrng: imx-rngc - check the rng type
On Tue, 28 Jan 2020 at 16:31, Martin Kaiser <martin@kaiser.cx> wrote:
>
> 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.
>
> Signed-off-by: Martin Kaiser <martin@kaiser.cx>
> ---
> drivers/char/hw_random/imx-rngc.c | 28 +++++++++++++++++++++++++++-
> 1 file changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/char/hw_random/imx-rngc.c b/drivers/char/hw_random/imx-rngc.c
> index 8222055b9e9b..27d85fced30b 100644
> --- 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:
> --
> 2.20.1
>

Reviewed-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>

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