From 746d9e9f62a6e8ba0eba2b83fc61cfe7fa8797ce Mon Sep 17 00:00:00 2001 From: Yeoreum Yun Date: Sat, 19 Jul 2025 13:27:46 +0300 Subject: [PATCH] tpm: tpm_crb_ffa: try to probe tpm_crb_ffa when it's built-in MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit To generate the boot_aggregate log in the IMA subsystem using TPM PCR values, the TPM driver must be built as built-in and must be probed before the IMA subsystem is initialized. However, when the TPM device operates over the FF-A protocol using the CRB interface, probing fails and returns -EPROBE_DEFER if the tpm_crb_ffa device — an FF-A device that provides the communication interface to the tpm_crb driver — has not yet been probed. This issue occurs because both crb_acpi_driver_init() and tpm_crb_ffa_driver_init() are registered with device_initcall. As a result, crb_acpi_driver_init() may be invoked before tpm_crb_ffa_driver_init(), which is responsible for probing the tpm_crb_ffa device. When this happens, IMA fails to detect the TPM device and logs the following message: | ima: No TPM chip found, activating TPM-bypass! Consequently, it cannot generate the boot_aggregate log with the PCR values provided by the TPM. To resolve this issue, the tpm_crb_ffa_init() function explicitly attempts to probe the tpm_crb_ffa by register tpm_crb_ffa driver so that when tpm_crb_ffa device is created before tpm_crb_ffa_init(), probe the tpm_crb_ffa device in tpm_crb_ffa_init() to finish probe the TPM device completely. This ensures that the TPM device using CRB over FF-A can be successfully probed, even if crb_acpi_driver_init() is called first. [ jarkko: reformatted some of the paragraphs because they were going past the 75 character boundary. ] Signed-off-by: Yeoreum Yun Reviewed-by: Mimi Zohar Reviewed-by: Sudeep Holla Reviewed-by: Jarkko Sakkinen Signed-off-by: Jarkko Sakkinen --- drivers/char/tpm/tpm_crb_ffa.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/drivers/char/tpm/tpm_crb_ffa.c b/drivers/char/tpm/tpm_crb_ffa.c index 4ead61f012996..462fcf6100208 100644 --- a/drivers/char/tpm/tpm_crb_ffa.c +++ b/drivers/char/tpm/tpm_crb_ffa.c @@ -115,6 +115,7 @@ struct tpm_crb_ffa { }; static struct tpm_crb_ffa *tpm_crb_ffa; +static struct ffa_driver tpm_crb_ffa_driver; static int tpm_crb_ffa_to_linux_errno(int errno) { @@ -168,13 +169,23 @@ static int tpm_crb_ffa_to_linux_errno(int errno) */ int tpm_crb_ffa_init(void) { + int ret = 0; + + if (!IS_MODULE(CONFIG_TCG_ARM_CRB_FFA)) { + ret = ffa_register(&tpm_crb_ffa_driver); + if (ret) { + tpm_crb_ffa = ERR_PTR(-ENODEV); + return ret; + } + } + if (!tpm_crb_ffa) - return -ENOENT; + ret = -ENOENT; if (IS_ERR_VALUE(tpm_crb_ffa)) - return -ENODEV; + ret = -ENODEV; - return 0; + return ret; } EXPORT_SYMBOL_GPL(tpm_crb_ffa_init); @@ -369,7 +380,9 @@ static struct ffa_driver tpm_crb_ffa_driver = { .id_table = tpm_crb_ffa_device_id, }; +#ifdef MODULE module_ffa_driver(tpm_crb_ffa_driver); +#endif MODULE_AUTHOR("Arm"); MODULE_DESCRIPTION("TPM CRB FFA driver"); -- 2.47.2