// SPDX-License-Identifier: GPL-2.0-only /* * Copyright (C) 2024 Arm Ltd. * * This device driver implements the TPM CRB start method * as defined in the TPM Service Command Response Buffer * Interface Over FF-A (DEN0138). */ #define pr_fmt(fmt) "CRB_FFA: " fmt #include #include "tpm_crb_ffa.h" /* TPM service function status codes */ #define CRB_FFA_OK 0x05000001 #define CRB_FFA_OK_RESULTS_RETURNED 0x05000002 #define CRB_FFA_NOFUNC 0x8e000001 #define CRB_FFA_NOTSUP 0x8e000002 #define CRB_FFA_INVARG 0x8e000005 #define CRB_FFA_INV_CRB_CTRL_DATA 0x8e000006 #define CRB_FFA_ALREADY 0x8e000009 #define CRB_FFA_DENIED 0x8e00000a #define CRB_FFA_NOMEM 0x8e00000b #define CRB_FFA_VERSION_MAJOR 1 #define CRB_FFA_VERSION_MINOR 0 /* version encoding */ #define CRB_FFA_MAJOR_VERSION_MASK GENMASK(30, 16) #define CRB_FFA_MINOR_VERSION_MASK GENMASK(15, 0) #define CRB_FFA_MAJOR_VERSION(x) ((u16)(FIELD_GET(CRB_FFA_MAJOR_VERSION_MASK, (x)))) #define CRB_FFA_MINOR_VERSION(x) ((u16)(FIELD_GET(CRB_FFA_MINOR_VERSION_MASK, (x)))) /* * Normal world sends requests with FFA_MSG_SEND_DIRECT_REQ and * responses are returned with FFA_MSG_SEND_DIRECT_RESP for normal * messages. * * All requests with FFA_MSG_SEND_DIRECT_REQ and FFA_MSG_SEND_DIRECT_RESP * are using the AArch32 SMC calling convention with register usage as * defined in FF-A specification: * w0: Function ID (0x8400006F or 0x84000070) * w1: Source/Destination IDs * w2: Reserved (MBZ) * w3-w7: Implementation defined, free to be used below */ /* * Returns the version of the interface that is available * Call register usage: * w3: Not used (MBZ) * w4: TPM service function ID, CRB_FFA_GET_INTERFACE_VERSION * w5-w7: Reserved (MBZ) * * Return register usage: * w3: Not used (MBZ) * w4: TPM service function status * w5: TPM service interface version * Bits[31:16]: major version * Bits[15:0]: minor version * w6-w7: Reserved (MBZ) * * Possible function status codes in register w4: * CRB_FFA_OK_RESULTS_RETURNED: The version of the interface has been * returned. */ #define CRB_FFA_GET_INTERFACE_VERSION 0x0f000001 /* * Return information on a given feature of the TPM service * Call register usage: * w3: Not used (MBZ) * w4: TPM service function ID, CRB_FFA_START * w5: Start function qualifier * Bits[31:8] (MBZ) * Bits[7:0] * 0: Notifies TPM that a command is ready to be processed * 1: Notifies TPM that a locality request is ready to be processed * w6: TPM locality, one of 0..4 * -If the start function qualifier is 0, identifies the locality * from where the command originated. * -If the start function qualifier is 1, identifies the locality * of the locality request * w6-w7: Reserved (MBZ) * * Return register usage: * w3: Not used (MBZ) * w4: TPM service function status * w5-w7: Reserved (MBZ) * * Possible function status codes in register w4: * CRB_FFA_OK: the TPM service has been notified successfully * CRB_FFA_INVARG: one or more arguments are not valid * CRB_FFA_INV_CRB_CTRL_DATA: CRB control data or locality control * data at the given TPM locality is not valid * CRB_FFA_DENIED: the TPM has previously disabled locality requests and * command processing at the given locality */ #define CRB_FFA_START 0x0f000201 struct tpm_crb_ffa { struct ffa_device *ffa_dev; u16 major_version; u16 minor_version; /* lock to protect sending of FF-A messages: */ struct mutex msg_data_lock; struct ffa_send_direct_data direct_msg_data; }; static struct tpm_crb_ffa *tpm_crb_ffa; static int tpm_crb_ffa_to_linux_errno(int errno) { int rc; switch (errno) { case CRB_FFA_OK: rc = 0; break; case CRB_FFA_OK_RESULTS_RETURNED: rc = 0; break; case CRB_FFA_NOFUNC: rc = -ENOENT; break; case CRB_FFA_NOTSUP: rc = -EPERM; break; case CRB_FFA_INVARG: rc = -EINVAL; break; case CRB_FFA_INV_CRB_CTRL_DATA: rc = -ENOEXEC; break; case CRB_FFA_ALREADY: rc = -EEXIST; break; case CRB_FFA_DENIED: rc = -EACCES; break; case CRB_FFA_NOMEM: rc = -ENOMEM; break; default: rc = -EINVAL; } return rc; } /** * tpm_crb_ffa_init - called by the CRB driver to do any needed initialization * * This function is called by the tpm_crb driver during the tpm_crb * driver's initialization. If the tpm_crb_ffa has not been probed * yet, returns -ENOENT in order to force a retry. If th ffa_crb * driver had been probed but failed with an error, returns -ENODEV * in order to prevent further retries. * * Return: 0 on success, negative error code on failure. */ int tpm_crb_ffa_init(void) { if (!tpm_crb_ffa) return -ENOENT; if (IS_ERR_VALUE(tpm_crb_ffa)) return -ENODEV; return 0; } EXPORT_SYMBOL_GPL(tpm_crb_ffa_init); static int __tpm_crb_ffa_send_recieve(unsigned long func_id, unsigned long a0, unsigned long a1, unsigned long a2) { const struct ffa_msg_ops *msg_ops; int ret; if (!tpm_crb_ffa) return -ENOENT; msg_ops = tpm_crb_ffa->ffa_dev->ops->msg_ops; memset(&tpm_crb_ffa->direct_msg_data, 0x00, sizeof(struct ffa_send_direct_data)); tpm_crb_ffa->direct_msg_data.data1 = func_id; tpm_crb_ffa->direct_msg_data.data2 = a0; tpm_crb_ffa->direct_msg_data.data3 = a1; tpm_crb_ffa->direct_msg_data.data4 = a2; ret = msg_ops->sync_send_receive(tpm_crb_ffa->ffa_dev, &tpm_crb_ffa->direct_msg_data); if (!ret) ret = tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data.data1); return ret; } /** * tpm_crb_ffa_get_interface_version() - gets the ABI version of the TPM service * @major: Pointer to caller-allocated buffer to hold the major version * number the ABI * @minor: Pointer to caller-allocated buffer to hold the minor version * number the ABI * * Returns the major and minor version of the ABI of the FF-A based TPM. * Allows the caller to evaluate its compatibility with the version of * the ABI. * * Return: 0 on success, negative error code on failure. */ int tpm_crb_ffa_get_interface_version(u16 *major, u16 *minor) { int rc; if (!tpm_crb_ffa) return -ENOENT; if (IS_ERR_VALUE(tpm_crb_ffa)) return -ENODEV; if (!major || !minor) return -EINVAL; guard(mutex)(&tpm_crb_ffa->msg_data_lock); rc = __tpm_crb_ffa_send_recieve(CRB_FFA_GET_INTERFACE_VERSION, 0x00, 0x00, 0x00); if (!rc) { *major = CRB_FFA_MAJOR_VERSION(tpm_crb_ffa->direct_msg_data.data2); *minor = CRB_FFA_MINOR_VERSION(tpm_crb_ffa->direct_msg_data.data2); } return rc; } EXPORT_SYMBOL_GPL(tpm_crb_ffa_get_interface_version); /** * tpm_crb_ffa_start() - signals the TPM that a field has changed in the CRB * @request_type: Identifies whether the change to the CRB is in the command * fields or locality fields. * @locality: Specifies the locality number. * * Used by the CRB driver * that might be useful to those using or modifying it. Begins with * empty comment line, and may include additional embedded empty * comment lines. * * Return: 0 on success, negative error code on failure. */ int tpm_crb_ffa_start(int request_type, int locality) { if (!tpm_crb_ffa) return -ENOENT; if (IS_ERR_VALUE(tpm_crb_ffa)) return -ENODEV; guard(mutex)(&tpm_crb_ffa->msg_data_lock); return __tpm_crb_ffa_send_recieve(CRB_FFA_START, request_type, locality, 0x00); } EXPORT_SYMBOL_GPL(tpm_crb_ffa_start); static int tpm_crb_ffa_probe(struct ffa_device *ffa_dev) { struct tpm_crb_ffa *p; int rc; /* only one instance of a TPM partition is supported */ if (tpm_crb_ffa && !IS_ERR_VALUE(tpm_crb_ffa)) return -EEXIST; tpm_crb_ffa = ERR_PTR(-ENODEV); // set tpm_crb_ffa so we can detect probe failure if (!ffa_partition_supports_direct_recv(ffa_dev)) { pr_err("TPM partition doesn't support direct message receive.\n"); return -EINVAL; } p = kzalloc(sizeof(*tpm_crb_ffa), GFP_KERNEL); if (!p) return -ENOMEM; tpm_crb_ffa = p; mutex_init(&tpm_crb_ffa->msg_data_lock); tpm_crb_ffa->ffa_dev = ffa_dev; ffa_dev_set_drvdata(ffa_dev, tpm_crb_ffa); /* if TPM is aarch32 use 32-bit SMCs */ if (!ffa_partition_check_property(ffa_dev, FFA_PARTITION_AARCH64_EXEC)) ffa_dev->ops->msg_ops->mode_32bit_set(ffa_dev); /* verify compatibility of TPM service version number */ rc = tpm_crb_ffa_get_interface_version(&tpm_crb_ffa->major_version, &tpm_crb_ffa->minor_version); if (rc) { pr_err("failed to get crb interface version. rc:%d", rc); goto out; } pr_info("ABI version %u.%u", tpm_crb_ffa->major_version, tpm_crb_ffa->minor_version); if (tpm_crb_ffa->major_version != CRB_FFA_VERSION_MAJOR || (tpm_crb_ffa->minor_version > 0 && tpm_crb_ffa->minor_version < CRB_FFA_VERSION_MINOR)) { pr_err("Incompatible ABI version"); goto out; } return 0; out: kfree(tpm_crb_ffa); tpm_crb_ffa = ERR_PTR(-ENODEV); return -EINVAL; } static void tpm_crb_ffa_remove(struct ffa_device *ffa_dev) { kfree(tpm_crb_ffa); tpm_crb_ffa = NULL; } static const struct ffa_device_id tpm_crb_ffa_device_id[] = { /* 17b862a4-1806-4faf-86b3-089a58353861 */ { UUID_INIT(0x17b862a4, 0x1806, 0x4faf, 0x86, 0xb3, 0x08, 0x9a, 0x58, 0x35, 0x38, 0x61) }, {} }; static struct ffa_driver tpm_crb_ffa_driver = { .name = "ffa-crb", .probe = tpm_crb_ffa_probe, .remove = tpm_crb_ffa_remove, .id_table = tpm_crb_ffa_device_id, }; module_ffa_driver(tpm_crb_ffa_driver); MODULE_AUTHOR("Arm"); MODULE_DESCRIPTION("TPM CRB FFA driver"); MODULE_LICENSE("GPL");