1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2024 Arm Ltd. 4 * 5 * This device driver implements the TPM CRB start method 6 * as defined in the TPM Service Command Response Buffer 7 * Interface Over FF-A (DEN0138). 8 */ 9 10 #define pr_fmt(fmt) "CRB_FFA: " fmt 11 12 #include <linux/arm_ffa.h> 13 #include "tpm_crb_ffa.h" 14 15 /* TPM service function status codes */ 16 #define CRB_FFA_OK 0x05000001 17 #define CRB_FFA_OK_RESULTS_RETURNED 0x05000002 18 #define CRB_FFA_NOFUNC 0x8e000001 19 #define CRB_FFA_NOTSUP 0x8e000002 20 #define CRB_FFA_INVARG 0x8e000005 21 #define CRB_FFA_INV_CRB_CTRL_DATA 0x8e000006 22 #define CRB_FFA_ALREADY 0x8e000009 23 #define CRB_FFA_DENIED 0x8e00000a 24 #define CRB_FFA_NOMEM 0x8e00000b 25 26 #define CRB_FFA_VERSION_MAJOR 1 27 #define CRB_FFA_VERSION_MINOR 0 28 29 /* version encoding */ 30 #define CRB_FFA_MAJOR_VERSION_MASK GENMASK(30, 16) 31 #define CRB_FFA_MINOR_VERSION_MASK GENMASK(15, 0) 32 #define CRB_FFA_MAJOR_VERSION(x) ((u16)(FIELD_GET(CRB_FFA_MAJOR_VERSION_MASK, (x)))) 33 #define CRB_FFA_MINOR_VERSION(x) ((u16)(FIELD_GET(CRB_FFA_MINOR_VERSION_MASK, (x)))) 34 35 /* 36 * Normal world sends requests with FFA_MSG_SEND_DIRECT_REQ and 37 * responses are returned with FFA_MSG_SEND_DIRECT_RESP for normal 38 * messages. 39 * 40 * All requests with FFA_MSG_SEND_DIRECT_REQ and FFA_MSG_SEND_DIRECT_RESP 41 * are using the AArch32 or AArch64 SMC calling convention with register usage 42 * as defined in FF-A specification: 43 * w0: Function ID 44 * -for 32-bit: 0x8400006F or 0x84000070 45 * -for 64-bit: 0xC400006F or 0xC4000070 46 * w1: Source/Destination IDs 47 * w2: Reserved (MBZ) 48 * w3-w7: Implementation defined, free to be used below 49 */ 50 51 /* 52 * Returns the version of the interface that is available 53 * Call register usage: 54 * w3: Not used (MBZ) 55 * w4: TPM service function ID, CRB_FFA_GET_INTERFACE_VERSION 56 * w5-w7: Reserved (MBZ) 57 * 58 * Return register usage: 59 * w3: Not used (MBZ) 60 * w4: TPM service function status 61 * w5: TPM service interface version 62 * Bits[31:16]: major version 63 * Bits[15:0]: minor version 64 * w6-w7: Reserved (MBZ) 65 * 66 * Possible function status codes in register w4: 67 * CRB_FFA_OK_RESULTS_RETURNED: The version of the interface has been 68 * returned. 69 */ 70 #define CRB_FFA_GET_INTERFACE_VERSION 0x0f000001 71 72 /* 73 * Notifies the TPM service that a TPM command or TPM locality request is 74 * ready to be processed, and allows the TPM service to process it. 75 * Call register usage: 76 * w3: Not used (MBZ) 77 * w4: TPM service function ID, CRB_FFA_START 78 * w5: Start function qualifier 79 * Bits[31:8] (MBZ) 80 * Bits[7:0] 81 * 0: Notifies TPM that a command is ready to be processed 82 * 1: Notifies TPM that a locality request is ready to be processed 83 * w6: TPM locality, one of 0..4 84 * -If the start function qualifier is 0, identifies the locality 85 * from where the command originated. 86 * -If the start function qualifier is 1, identifies the locality 87 * of the locality request 88 * w6-w7: Reserved (MBZ) 89 * 90 * Return register usage: 91 * w3: Not used (MBZ) 92 * w4: TPM service function status 93 * w5-w7: Reserved (MBZ) 94 * 95 * Possible function status codes in register w4: 96 * CRB_FFA_OK: the TPM service has been notified successfully 97 * CRB_FFA_INVARG: one or more arguments are not valid 98 * CRB_FFA_INV_CRB_CTRL_DATA: CRB control data or locality control 99 * data at the given TPM locality is not valid 100 * CRB_FFA_DENIED: the TPM has previously disabled locality requests and 101 * command processing at the given locality 102 */ 103 #define CRB_FFA_START 0x0f000201 104 105 struct tpm_crb_ffa { 106 struct ffa_device *ffa_dev; 107 u16 major_version; 108 u16 minor_version; 109 /* lock to protect sending of FF-A messages: */ 110 struct mutex msg_data_lock; 111 union { 112 struct ffa_send_direct_data direct_msg_data; 113 struct ffa_send_direct_data2 direct_msg_data2; 114 }; 115 }; 116 117 static struct tpm_crb_ffa *tpm_crb_ffa; 118 119 static int tpm_crb_ffa_to_linux_errno(int errno) 120 { 121 int rc; 122 123 switch (errno) { 124 case CRB_FFA_OK: 125 rc = 0; 126 break; 127 case CRB_FFA_OK_RESULTS_RETURNED: 128 rc = 0; 129 break; 130 case CRB_FFA_NOFUNC: 131 rc = -ENOENT; 132 break; 133 case CRB_FFA_NOTSUP: 134 rc = -EPERM; 135 break; 136 case CRB_FFA_INVARG: 137 rc = -EINVAL; 138 break; 139 case CRB_FFA_INV_CRB_CTRL_DATA: 140 rc = -ENOEXEC; 141 break; 142 case CRB_FFA_ALREADY: 143 rc = -EEXIST; 144 break; 145 case CRB_FFA_DENIED: 146 rc = -EACCES; 147 break; 148 case CRB_FFA_NOMEM: 149 rc = -ENOMEM; 150 break; 151 default: 152 rc = -EINVAL; 153 } 154 155 return rc; 156 } 157 158 /** 159 * tpm_crb_ffa_init - called by the CRB driver to do any needed initialization 160 * 161 * This function is called by the tpm_crb driver during the tpm_crb 162 * driver's initialization. If the tpm_crb_ffa has not been probed 163 * yet, returns -ENOENT in order to force a retry. If th ffa_crb 164 * driver had been probed but failed with an error, returns -ENODEV 165 * in order to prevent further retries. 166 * 167 * Return: 0 on success, negative error code on failure. 168 */ 169 int tpm_crb_ffa_init(void) 170 { 171 if (!tpm_crb_ffa) 172 return -ENOENT; 173 174 if (IS_ERR_VALUE(tpm_crb_ffa)) 175 return -ENODEV; 176 177 return 0; 178 } 179 EXPORT_SYMBOL_GPL(tpm_crb_ffa_init); 180 181 static int __tpm_crb_ffa_send_recieve(unsigned long func_id, 182 unsigned long a0, 183 unsigned long a1, 184 unsigned long a2) 185 { 186 const struct ffa_msg_ops *msg_ops; 187 int ret; 188 189 if (!tpm_crb_ffa) 190 return -ENOENT; 191 192 msg_ops = tpm_crb_ffa->ffa_dev->ops->msg_ops; 193 194 if (ffa_partition_supports_direct_req2_recv(tpm_crb_ffa->ffa_dev)) { 195 memset(&tpm_crb_ffa->direct_msg_data2, 0x00, 196 sizeof(struct ffa_send_direct_data2)); 197 198 tpm_crb_ffa->direct_msg_data2.data[0] = func_id; 199 tpm_crb_ffa->direct_msg_data2.data[1] = a0; 200 tpm_crb_ffa->direct_msg_data2.data[2] = a1; 201 tpm_crb_ffa->direct_msg_data2.data[3] = a2; 202 203 ret = msg_ops->sync_send_receive2(tpm_crb_ffa->ffa_dev, 204 &tpm_crb_ffa->direct_msg_data2); 205 if (!ret) 206 ret = tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data2.data[0]); 207 } else { 208 memset(&tpm_crb_ffa->direct_msg_data, 0x00, 209 sizeof(struct ffa_send_direct_data)); 210 211 tpm_crb_ffa->direct_msg_data.data1 = func_id; 212 tpm_crb_ffa->direct_msg_data.data2 = a0; 213 tpm_crb_ffa->direct_msg_data.data3 = a1; 214 tpm_crb_ffa->direct_msg_data.data4 = a2; 215 216 ret = msg_ops->sync_send_receive(tpm_crb_ffa->ffa_dev, 217 &tpm_crb_ffa->direct_msg_data); 218 if (!ret) 219 ret = tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data.data1); 220 } 221 222 223 return ret; 224 } 225 226 /** 227 * tpm_crb_ffa_get_interface_version() - gets the ABI version of the TPM service 228 * @major: Pointer to caller-allocated buffer to hold the major version 229 * number the ABI 230 * @minor: Pointer to caller-allocated buffer to hold the minor version 231 * number the ABI 232 * 233 * Returns the major and minor version of the ABI of the FF-A based TPM. 234 * Allows the caller to evaluate its compatibility with the version of 235 * the ABI. 236 * 237 * Return: 0 on success, negative error code on failure. 238 */ 239 int tpm_crb_ffa_get_interface_version(u16 *major, u16 *minor) 240 { 241 int rc; 242 243 if (!tpm_crb_ffa) 244 return -ENOENT; 245 246 if (IS_ERR_VALUE(tpm_crb_ffa)) 247 return -ENODEV; 248 249 if (!major || !minor) 250 return -EINVAL; 251 252 guard(mutex)(&tpm_crb_ffa->msg_data_lock); 253 254 rc = __tpm_crb_ffa_send_recieve(CRB_FFA_GET_INTERFACE_VERSION, 0x00, 0x00, 0x00); 255 if (!rc) { 256 if (ffa_partition_supports_direct_req2_recv(tpm_crb_ffa->ffa_dev)) { 257 *major = CRB_FFA_MAJOR_VERSION(tpm_crb_ffa->direct_msg_data2.data[1]); 258 *minor = CRB_FFA_MINOR_VERSION(tpm_crb_ffa->direct_msg_data2.data[1]); 259 } else { 260 *major = CRB_FFA_MAJOR_VERSION(tpm_crb_ffa->direct_msg_data.data2); 261 *minor = CRB_FFA_MINOR_VERSION(tpm_crb_ffa->direct_msg_data.data2); 262 } 263 } 264 265 return rc; 266 } 267 EXPORT_SYMBOL_GPL(tpm_crb_ffa_get_interface_version); 268 269 /** 270 * tpm_crb_ffa_start() - signals the TPM that a field has changed in the CRB 271 * @request_type: Identifies whether the change to the CRB is in the command 272 * fields or locality fields. 273 * @locality: Specifies the locality number. 274 * 275 * Used by the CRB driver 276 * that might be useful to those using or modifying it. Begins with 277 * empty comment line, and may include additional embedded empty 278 * comment lines. 279 * 280 * Return: 0 on success, negative error code on failure. 281 */ 282 int tpm_crb_ffa_start(int request_type, int locality) 283 { 284 if (!tpm_crb_ffa) 285 return -ENOENT; 286 287 if (IS_ERR_VALUE(tpm_crb_ffa)) 288 return -ENODEV; 289 290 guard(mutex)(&tpm_crb_ffa->msg_data_lock); 291 292 return __tpm_crb_ffa_send_recieve(CRB_FFA_START, request_type, locality, 0x00); 293 } 294 EXPORT_SYMBOL_GPL(tpm_crb_ffa_start); 295 296 static int tpm_crb_ffa_probe(struct ffa_device *ffa_dev) 297 { 298 struct tpm_crb_ffa *p; 299 int rc; 300 301 /* only one instance of a TPM partition is supported */ 302 if (tpm_crb_ffa && !IS_ERR_VALUE(tpm_crb_ffa)) 303 return -EEXIST; 304 305 tpm_crb_ffa = ERR_PTR(-ENODEV); // set tpm_crb_ffa so we can detect probe failure 306 307 if (!ffa_partition_supports_direct_recv(ffa_dev) && 308 !ffa_partition_supports_direct_req2_recv(ffa_dev)) { 309 dev_warn(&ffa_dev->dev, "partition doesn't support direct message receive.\n"); 310 return -EINVAL; 311 } 312 313 p = kzalloc(sizeof(*tpm_crb_ffa), GFP_KERNEL); 314 if (!p) 315 return -ENOMEM; 316 tpm_crb_ffa = p; 317 318 mutex_init(&tpm_crb_ffa->msg_data_lock); 319 tpm_crb_ffa->ffa_dev = ffa_dev; 320 ffa_dev_set_drvdata(ffa_dev, tpm_crb_ffa); 321 322 /* if TPM is aarch32 use 32-bit SMCs */ 323 if (!ffa_partition_check_property(ffa_dev, FFA_PARTITION_AARCH64_EXEC)) 324 ffa_dev->ops->msg_ops->mode_32bit_set(ffa_dev); 325 326 /* verify compatibility of TPM service version number */ 327 rc = tpm_crb_ffa_get_interface_version(&tpm_crb_ffa->major_version, 328 &tpm_crb_ffa->minor_version); 329 if (rc) { 330 dev_err(&ffa_dev->dev, "failed to get crb interface version. rc:%d\n", rc); 331 goto out; 332 } 333 334 dev_info(&ffa_dev->dev, "ABI version %u.%u\n", tpm_crb_ffa->major_version, 335 tpm_crb_ffa->minor_version); 336 337 if (tpm_crb_ffa->major_version != CRB_FFA_VERSION_MAJOR || 338 (tpm_crb_ffa->minor_version > 0 && 339 tpm_crb_ffa->minor_version < CRB_FFA_VERSION_MINOR)) { 340 dev_warn(&ffa_dev->dev, "Incompatible ABI version\n"); 341 goto out; 342 } 343 344 return 0; 345 346 out: 347 kfree(tpm_crb_ffa); 348 tpm_crb_ffa = ERR_PTR(-ENODEV); 349 return -EINVAL; 350 } 351 352 static void tpm_crb_ffa_remove(struct ffa_device *ffa_dev) 353 { 354 kfree(tpm_crb_ffa); 355 tpm_crb_ffa = NULL; 356 } 357 358 static const struct ffa_device_id tpm_crb_ffa_device_id[] = { 359 /* 17b862a4-1806-4faf-86b3-089a58353861 */ 360 { UUID_INIT(0x17b862a4, 0x1806, 0x4faf, 361 0x86, 0xb3, 0x08, 0x9a, 0x58, 0x35, 0x38, 0x61) }, 362 {} 363 }; 364 365 static struct ffa_driver tpm_crb_ffa_driver = { 366 .name = "ffa-crb", 367 .probe = tpm_crb_ffa_probe, 368 .remove = tpm_crb_ffa_remove, 369 .id_table = tpm_crb_ffa_device_id, 370 }; 371 372 module_ffa_driver(tpm_crb_ffa_driver); 373 374 MODULE_AUTHOR("Arm"); 375 MODULE_DESCRIPTION("TPM CRB FFA driver"); 376 MODULE_LICENSE("GPL"); 377