[PATCH 08/10] tpm: Add the RNG child device

[Heinrich Schuchardt]

On 2/24/22 19:05, Sughosh Ganu wrote:
> The TPM device comes with the random number generator(RNG)
> functionality which is built into the TPM device. Add logic to add the
> RNG child device in the TPM uclass post probe callback.
>
> The RNG device can then be used to pass a set of random bytes to the
> linux kernel, need for address space randomisation through the
> EFI_RNG_PROTOCOL interface.
>
> Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
> ---
>   drivers/tpm/tpm-uclass.c | 58 +++++++++++++++++++++++++++++++++++++---
>   1 file changed, 54 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/tpm/tpm-uclass.c b/drivers/tpm/tpm-uclass.c
> index 8619da89d8..383cc7bc48 100644
> --- a/drivers/tpm/tpm-uclass.c
> +++ b/drivers/tpm/tpm-uclass.c
> @@ -16,6 +16,11 @@
>   #include <tpm-v2.h>
>   #include "tpm_internal.h"
>
> +#include <dm/lists.h>
> +
> +#define TPM_RNG1_DRV_NAME	"tpm1-rng"
> +#define TPM_RNG2_DRV_NAME	"tpm2-rng"
> +
>   bool is_tpm1(struct udevice *dev)
>   {
>   	return IS_ENABLED(CONFIG_TPM_V1) && tpm_get_version(dev) == TPM_V1;
> @@ -147,12 +152,57 @@ int tpm_xfer(struct udevice *dev, const uint8_t *sendbuf, size_t send_size,
>   	return 0;
>   }
>
> +#if IS_ENABLED(CONFIG_TPM)

This is is superfluous.
This file is only compiled if CONFIG_$(SPL_TPL_)TPM = y.

Best regards

Heinrich

> +static int tpm_uclass_post_probe(struct udevice *dev)
> +{
> +	int ret;
> +	const char *drv = is_tpm1(dev) ? TPM_RNG1_DRV_NAME : TPM_RNG2_DRV_NAME;
> +	struct udevice *child;
> +
> +	ret = device_bind_driver(dev, drv, "tpm-rng0", &child);
> +	if (ret == -ENOENT) {
> +		log_err("No driver configured for tpm-rng device\n");
> +		return 0;
> +	}
> +
> +	if (ret) {
> +		log_err("Unable to bind rng driver with the tpm-rng device\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int tpm_uclass_child_pre_probe(struct udevice *dev)
> +{
> +	int ret;
> +
> +	ret = tpm_open(dev->parent);
> +	if (ret == -EBUSY) {
> +		log_info("TPM device already opened\n");
> +	} else if (ret) {
> +		log_err("Unable to open TPM device\n");
> +		return ret;
> +	}
> +
> +	ret = tpm_startup(dev->parent, TPM_ST_CLEAR);
> +	if (ret)
> +		log_err("Unable to start TPM device\n");
> +
> +	return ret;
> +}
> +#endif /* CONFIG_TPM */
> +
>   UCLASS_DRIVER(tpm) = {
> -	.id		= UCLASS_TPM,
> -	.name		= "tpm",
> -	.flags		= DM_UC_FLAG_SEQ_ALIAS,
> +	.id			= UCLASS_TPM,
> +	.name			= "tpm",
> +	.flags			= DM_UC_FLAG_SEQ_ALIAS,
>   #if CONFIG_IS_ENABLED(OF_REAL)
> -	.post_bind	= dm_scan_fdt_dev,
> +	.post_bind		= dm_scan_fdt_dev,
> +#endif
> +#if IS_ENABLED(CONFIG_TPM)
> +	.post_probe		= tpm_uclass_post_probe,
> +	.child_pre_probe	= tpm_uclass_child_pre_probe,
>   #endif
>   	.per_device_auto	= sizeof(struct tpm_chip_priv),
>   };