diff options
Diffstat (limited to 'drivers/char/tpm/tpm_crb_ffa.c')
| -rw-r--r-- | drivers/char/tpm/tpm_crb_ffa.c | 376 |
1 files changed, 376 insertions, 0 deletions
diff --git a/drivers/char/tpm/tpm_crb_ffa.c b/drivers/char/tpm/tpm_crb_ffa.c new file mode 100644 index 000000000000..4ead61f01299 --- /dev/null +++ b/drivers/char/tpm/tpm_crb_ffa.c @@ -0,0 +1,376 @@ +// 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 <linux/arm_ffa.h> +#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 or AArch64 SMC calling convention with register usage + * as defined in FF-A specification: + * w0: Function ID + * -for 32-bit: 0x8400006F or 0x84000070 + * -for 64-bit: 0xC400006F or 0xC4000070 + * 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 + +/* + * Notifies the TPM service that a TPM command or TPM locality request is + * ready to be processed, and allows the TPM service to process it. + * 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; + union { + struct ffa_send_direct_data direct_msg_data; + struct ffa_send_direct_data2 direct_msg_data2; + }; +}; + +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; + + if (ffa_partition_supports_direct_req2_recv(tpm_crb_ffa->ffa_dev)) { + memset(&tpm_crb_ffa->direct_msg_data2, 0x00, + sizeof(struct ffa_send_direct_data2)); + + tpm_crb_ffa->direct_msg_data2.data[0] = func_id; + tpm_crb_ffa->direct_msg_data2.data[1] = a0; + tpm_crb_ffa->direct_msg_data2.data[2] = a1; + tpm_crb_ffa->direct_msg_data2.data[3] = a2; + + ret = msg_ops->sync_send_receive2(tpm_crb_ffa->ffa_dev, + &tpm_crb_ffa->direct_msg_data2); + if (!ret) + ret = tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data2.data[0]); + } else { + 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) { + if (ffa_partition_supports_direct_req2_recv(tpm_crb_ffa->ffa_dev)) { + *major = CRB_FFA_MAJOR_VERSION(tpm_crb_ffa->direct_msg_data2.data[1]); + *minor = CRB_FFA_MINOR_VERSION(tpm_crb_ffa->direct_msg_data2.data[1]); + } else { + *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) && + !ffa_partition_supports_direct_req2_recv(ffa_dev)) { + dev_warn(&ffa_dev->dev, "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) { + dev_err(&ffa_dev->dev, "failed to get crb interface version. rc:%d\n", rc); + goto out; + } + + dev_info(&ffa_dev->dev, "ABI version %u.%u\n", 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)) { + dev_warn(&ffa_dev->dev, "Incompatible ABI version\n"); + 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"); |