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 <linux/delay.h> 14 #include <linux/moduleparam.h> 15 #include "tpm_crb_ffa.h" 16 17 static unsigned int busy_timeout_ms = 2000; 18 19 module_param(busy_timeout_ms, uint, 0644); 20 MODULE_PARM_DESC(busy_timeout_ms, 21 "Maximum time in ms to retry before giving up on busy"); 22 23 /* TPM service function status codes */ 24 #define CRB_FFA_OK 0x05000001 25 #define CRB_FFA_OK_RESULTS_RETURNED 0x05000002 26 #define CRB_FFA_NOFUNC 0x8e000001 27 #define CRB_FFA_NOTSUP 0x8e000002 28 #define CRB_FFA_INVARG 0x8e000005 29 #define CRB_FFA_INV_CRB_CTRL_DATA 0x8e000006 30 #define CRB_FFA_ALREADY 0x8e000009 31 #define CRB_FFA_DENIED 0x8e00000a 32 #define CRB_FFA_NOMEM 0x8e00000b 33 34 #define CRB_FFA_VERSION_MAJOR 1 35 #define CRB_FFA_VERSION_MINOR 0 36 37 /* version encoding */ 38 #define CRB_FFA_MAJOR_VERSION_MASK GENMASK(30, 16) 39 #define CRB_FFA_MINOR_VERSION_MASK GENMASK(15, 0) 40 #define CRB_FFA_MAJOR_VERSION(x) ((u16)(FIELD_GET(CRB_FFA_MAJOR_VERSION_MASK, (x)))) 41 #define CRB_FFA_MINOR_VERSION(x) ((u16)(FIELD_GET(CRB_FFA_MINOR_VERSION_MASK, (x)))) 42 43 /* 44 * Normal world sends requests with FFA_MSG_SEND_DIRECT_REQ and 45 * responses are returned with FFA_MSG_SEND_DIRECT_RESP for normal 46 * messages. 47 * 48 * All requests with FFA_MSG_SEND_DIRECT_REQ and FFA_MSG_SEND_DIRECT_RESP 49 * are using the AArch32 or AArch64 SMC calling convention with register usage 50 * as defined in FF-A specification: 51 * w0: Function ID 52 * -for 32-bit: 0x8400006F or 0x84000070 53 * -for 64-bit: 0xC400006F or 0xC4000070 54 * w1: Source/Destination IDs 55 * w2: Reserved (MBZ) 56 * w3-w7: Implementation defined, free to be used below 57 */ 58 59 /* 60 * Returns the version of the interface that is available 61 * Call register usage: 62 * w3: Not used (MBZ) 63 * w4: TPM service function ID, CRB_FFA_GET_INTERFACE_VERSION 64 * w5-w7: Reserved (MBZ) 65 * 66 * Return register usage: 67 * w3: Not used (MBZ) 68 * w4: TPM service function status 69 * w5: TPM service interface version 70 * Bits[31:16]: major version 71 * Bits[15:0]: minor version 72 * w6-w7: Reserved (MBZ) 73 * 74 * Possible function status codes in register w4: 75 * CRB_FFA_OK_RESULTS_RETURNED: The version of the interface has been 76 * returned. 77 */ 78 #define CRB_FFA_GET_INTERFACE_VERSION 0x0f000001 79 80 /* 81 * Notifies the TPM service that a TPM command or TPM locality request is 82 * ready to be processed, and allows the TPM service to process it. 83 * Call register usage: 84 * w3: Not used (MBZ) 85 * w4: TPM service function ID, CRB_FFA_START 86 * w5: Start function qualifier 87 * Bits[31:8] (MBZ) 88 * Bits[7:0] 89 * 0: Notifies TPM that a command is ready to be processed 90 * 1: Notifies TPM that a locality request is ready to be processed 91 * w6: TPM locality, one of 0..4 92 * -If the start function qualifier is 0, identifies the locality 93 * from where the command originated. 94 * -If the start function qualifier is 1, identifies the locality 95 * of the locality request 96 * w6-w7: Reserved (MBZ) 97 * 98 * Return register usage: 99 * w3: Not used (MBZ) 100 * w4: TPM service function status 101 * w5-w7: Reserved (MBZ) 102 * 103 * Possible function status codes in register w4: 104 * CRB_FFA_OK: the TPM service has been notified successfully 105 * CRB_FFA_INVARG: one or more arguments are not valid 106 * CRB_FFA_INV_CRB_CTRL_DATA: CRB control data or locality control 107 * data at the given TPM locality is not valid 108 * CRB_FFA_DENIED: the TPM has previously disabled locality requests and 109 * command processing at the given locality 110 */ 111 #define CRB_FFA_START 0x0f000201 112 113 struct tpm_crb_ffa { 114 struct ffa_device *ffa_dev; 115 u16 major_version; 116 u16 minor_version; 117 /* lock to protect sending of FF-A messages: */ 118 struct mutex msg_data_lock; 119 union { 120 struct ffa_send_direct_data direct_msg_data; 121 struct ffa_send_direct_data2 direct_msg_data2; 122 }; 123 }; 124 125 static struct tpm_crb_ffa *tpm_crb_ffa; 126 static struct ffa_driver tpm_crb_ffa_driver; 127 128 static int tpm_crb_ffa_to_linux_errno(int errno) 129 { 130 int rc; 131 132 switch (errno) { 133 case CRB_FFA_OK: 134 rc = 0; 135 break; 136 case CRB_FFA_OK_RESULTS_RETURNED: 137 rc = 0; 138 break; 139 case CRB_FFA_NOFUNC: 140 rc = -ENOENT; 141 break; 142 case CRB_FFA_NOTSUP: 143 rc = -EPERM; 144 break; 145 case CRB_FFA_INVARG: 146 rc = -EINVAL; 147 break; 148 case CRB_FFA_INV_CRB_CTRL_DATA: 149 rc = -ENOEXEC; 150 break; 151 case CRB_FFA_ALREADY: 152 rc = -EEXIST; 153 break; 154 case CRB_FFA_DENIED: 155 rc = -EACCES; 156 break; 157 case CRB_FFA_NOMEM: 158 rc = -ENOMEM; 159 break; 160 default: 161 rc = -EINVAL; 162 } 163 164 return rc; 165 } 166 167 /** 168 * tpm_crb_ffa_init - called by the CRB driver to do any needed initialization 169 * 170 * This function is called by the tpm_crb driver during the tpm_crb 171 * driver's initialization. If the tpm_crb_ffa has not been probed 172 * yet, returns -ENOENT in order to force a retry. If th ffa_crb 173 * driver had been probed but failed with an error, returns -ENODEV 174 * in order to prevent further retries. 175 * 176 * Return: 0 on success, negative error code on failure. 177 */ 178 int tpm_crb_ffa_init(void) 179 { 180 if (!tpm_crb_ffa) 181 return -ENOENT; 182 183 if (IS_ERR_VALUE(tpm_crb_ffa)) 184 return -ENODEV; 185 186 return 0; 187 } 188 EXPORT_SYMBOL_GPL(tpm_crb_ffa_init); 189 190 static int __tpm_crb_ffa_try_send_receive(unsigned long func_id, 191 unsigned long a0, unsigned long a1, 192 unsigned long a2) 193 { 194 const struct ffa_msg_ops *msg_ops; 195 int ret; 196 197 msg_ops = tpm_crb_ffa->ffa_dev->ops->msg_ops; 198 199 if (ffa_partition_supports_direct_req2_recv(tpm_crb_ffa->ffa_dev)) { 200 tpm_crb_ffa->direct_msg_data2 = (struct ffa_send_direct_data2){ 201 .data = { func_id, a0, a1, a2 }, 202 }; 203 204 ret = msg_ops->sync_send_receive2(tpm_crb_ffa->ffa_dev, 205 &tpm_crb_ffa->direct_msg_data2); 206 if (!ret) 207 ret = tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data2.data[0]); 208 } else { 209 tpm_crb_ffa->direct_msg_data = (struct ffa_send_direct_data){ 210 .data1 = func_id, 211 .data2 = a0, 212 .data3 = a1, 213 .data4 = a2, 214 }; 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 return ret; 223 } 224 225 static int __tpm_crb_ffa_send_receive(unsigned long func_id, unsigned long a0, 226 unsigned long a1, unsigned long a2) 227 { 228 ktime_t start, stop; 229 int ret; 230 231 if (!tpm_crb_ffa) 232 return -ENOENT; 233 234 start = ktime_get(); 235 stop = ktime_add(start, ms_to_ktime(busy_timeout_ms)); 236 237 for (;;) { 238 ret = __tpm_crb_ffa_try_send_receive(func_id, a0, a1, a2); 239 if (ret != -EBUSY) 240 break; 241 242 usleep_range(50, 100); 243 if (ktime_after(ktime_get(), stop)) { 244 dev_warn(&tpm_crb_ffa->ffa_dev->dev, 245 "Busy retry timed out\n"); 246 break; 247 } 248 } 249 250 return ret; 251 } 252 253 /** 254 * tpm_crb_ffa_get_interface_version() - gets the ABI version of the TPM service 255 * @major: Pointer to caller-allocated buffer to hold the major version 256 * number the ABI 257 * @minor: Pointer to caller-allocated buffer to hold the minor version 258 * number the ABI 259 * 260 * Returns the major and minor version of the ABI of the FF-A based TPM. 261 * Allows the caller to evaluate its compatibility with the version of 262 * the ABI. 263 * 264 * Return: 0 on success, negative error code on failure. 265 */ 266 static int tpm_crb_ffa_get_interface_version(u16 *major, u16 *minor) 267 { 268 int rc; 269 270 if (!tpm_crb_ffa) 271 return -ENOENT; 272 273 if (IS_ERR_VALUE(tpm_crb_ffa)) 274 return -ENODEV; 275 276 if (!major || !minor) 277 return -EINVAL; 278 279 guard(mutex)(&tpm_crb_ffa->msg_data_lock); 280 281 rc = __tpm_crb_ffa_send_receive(CRB_FFA_GET_INTERFACE_VERSION, 0x00, 0x00, 0x00); 282 if (!rc) { 283 if (ffa_partition_supports_direct_req2_recv(tpm_crb_ffa->ffa_dev)) { 284 *major = CRB_FFA_MAJOR_VERSION(tpm_crb_ffa->direct_msg_data2.data[1]); 285 *minor = CRB_FFA_MINOR_VERSION(tpm_crb_ffa->direct_msg_data2.data[1]); 286 } else { 287 *major = CRB_FFA_MAJOR_VERSION(tpm_crb_ffa->direct_msg_data.data2); 288 *minor = CRB_FFA_MINOR_VERSION(tpm_crb_ffa->direct_msg_data.data2); 289 } 290 } 291 292 return rc; 293 } 294 295 /** 296 * tpm_crb_ffa_start() - signals the TPM that a field has changed in the CRB 297 * @request_type: Identifies whether the change to the CRB is in the command 298 * fields or locality fields. 299 * @locality: Specifies the locality number. 300 * 301 * Used by the CRB driver 302 * that might be useful to those using or modifying it. Begins with 303 * empty comment line, and may include additional embedded empty 304 * comment lines. 305 * 306 * Return: 0 on success, negative error code on failure. 307 */ 308 int tpm_crb_ffa_start(int request_type, int locality) 309 { 310 if (!tpm_crb_ffa) 311 return -ENOENT; 312 313 if (IS_ERR_VALUE(tpm_crb_ffa)) 314 return -ENODEV; 315 316 guard(mutex)(&tpm_crb_ffa->msg_data_lock); 317 318 return __tpm_crb_ffa_send_receive(CRB_FFA_START, request_type, locality, 0x00); 319 } 320 EXPORT_SYMBOL_GPL(tpm_crb_ffa_start); 321 322 static int tpm_crb_ffa_probe(struct ffa_device *ffa_dev) 323 { 324 struct tpm_crb_ffa *p; 325 int rc; 326 327 /* only one instance of a TPM partition is supported */ 328 if (tpm_crb_ffa && !IS_ERR_VALUE(tpm_crb_ffa)) 329 return -EEXIST; 330 331 tpm_crb_ffa = ERR_PTR(-ENODEV); // set tpm_crb_ffa so we can detect probe failure 332 333 if (!ffa_partition_supports_direct_recv(ffa_dev) && 334 !ffa_partition_supports_direct_req2_recv(ffa_dev)) { 335 dev_warn(&ffa_dev->dev, "partition doesn't support direct message receive.\n"); 336 return -EINVAL; 337 } 338 339 p = kzalloc_obj(*tpm_crb_ffa); 340 if (!p) 341 return -ENOMEM; 342 tpm_crb_ffa = p; 343 344 mutex_init(&tpm_crb_ffa->msg_data_lock); 345 tpm_crb_ffa->ffa_dev = ffa_dev; 346 ffa_dev_set_drvdata(ffa_dev, tpm_crb_ffa); 347 348 /* if TPM is aarch32 use 32-bit SMCs */ 349 if (!ffa_partition_check_property(ffa_dev, FFA_PARTITION_AARCH64_EXEC)) 350 ffa_dev->ops->msg_ops->mode_32bit_set(ffa_dev); 351 352 /* verify compatibility of TPM service version number */ 353 rc = tpm_crb_ffa_get_interface_version(&tpm_crb_ffa->major_version, 354 &tpm_crb_ffa->minor_version); 355 if (rc) { 356 dev_err(&ffa_dev->dev, "failed to get crb interface version. rc:%d\n", rc); 357 goto out; 358 } 359 360 dev_info(&ffa_dev->dev, "ABI version %u.%u\n", tpm_crb_ffa->major_version, 361 tpm_crb_ffa->minor_version); 362 363 if (tpm_crb_ffa->major_version != CRB_FFA_VERSION_MAJOR || 364 (tpm_crb_ffa->minor_version > 0 && 365 tpm_crb_ffa->minor_version < CRB_FFA_VERSION_MINOR)) { 366 dev_warn(&ffa_dev->dev, "Incompatible ABI version\n"); 367 goto out; 368 } 369 370 return 0; 371 372 out: 373 kfree(tpm_crb_ffa); 374 tpm_crb_ffa = ERR_PTR(-ENODEV); 375 return -EINVAL; 376 } 377 378 static void tpm_crb_ffa_remove(struct ffa_device *ffa_dev) 379 { 380 kfree(tpm_crb_ffa); 381 tpm_crb_ffa = NULL; 382 } 383 384 static const struct ffa_device_id tpm_crb_ffa_device_id[] = { 385 /* 17b862a4-1806-4faf-86b3-089a58353861 */ 386 { UUID_INIT(0x17b862a4, 0x1806, 0x4faf, 387 0x86, 0xb3, 0x08, 0x9a, 0x58, 0x35, 0x38, 0x61) }, 388 {} 389 }; 390 391 static struct ffa_driver tpm_crb_ffa_driver = { 392 .name = "ffa-crb", 393 .probe = tpm_crb_ffa_probe, 394 .remove = tpm_crb_ffa_remove, 395 .id_table = tpm_crb_ffa_device_id, 396 }; 397 398 module_ffa_driver(tpm_crb_ffa_driver); 399 400 MODULE_AUTHOR("Arm"); 401 MODULE_DESCRIPTION("TPM CRB FFA driver"); 402 MODULE_LICENSE("GPL"); 403