From aedd45138ee61b4f5a48a2be9a358092a214edd5 Mon Sep 17 00:00:00 2001 From: Sughosh Ganu Date: Fri, 22 Jul 2022 21:32:05 +0530 Subject: [PATCH] tpm: Add the RNG child device 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. No compatible string is provided because this is not available in the binding defined by Linux. If multiple rand devices are in the system, then some method of selecting them (other than device tree) will need to be used, or a binding will need to be added. Signed-off-by: Sughosh Ganu Reviewed-by: Ilias Apalodimas Signed-off-by: Ilias Apalodimas --- drivers/tpm/tpm-uclass.c | 40 ++++++++++++++++++++++++++++++++++------ 1 file changed, 34 insertions(+), 6 deletions(-) diff --git a/drivers/tpm/tpm-uclass.c b/drivers/tpm/tpm-uclass.c index f67fe1019b..0eb35f50c4 100644 --- a/drivers/tpm/tpm-uclass.c +++ b/drivers/tpm/tpm-uclass.c @@ -9,12 +9,16 @@ #include #include #include -#include -#include +#include #include #include +#include +#include +#include #include "tpm_internal.h" +#define TPM_RNG_DRV_NAME "tpm-rng" + int tpm_open(struct udevice *dev) { struct tpm_ops *ops = tpm_get_ops(dev); @@ -136,12 +140,36 @@ int tpm_xfer(struct udevice *dev, const uint8_t *sendbuf, size_t send_size, return 0; } +static int tpm_uclass_post_probe(struct udevice *dev) +{ + int ret; + const char *drv = TPM_RNG_DRV_NAME; + struct udevice *child; + + if (CONFIG_IS_ENABLED(TPM_RNG)) { + ret = device_find_first_child_by_uclass(dev, UCLASS_RNG, + &child); + + if (ret != -ENODEV) { + log_debug("RNG child already added to the TPM device\n"); + return ret; + } + + ret = device_bind_driver(dev, drv, TPM_RNG_DRV_NAME, &child); + if (ret) + return log_msg_ret("bind", ret); + } + + return 0; +} + 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 + .post_probe = tpm_uclass_post_probe, .per_device_auto = sizeof(struct tpm_chip_priv), }; -- 2.39.5