tpm_crb_ffa.c

  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
 17static unsigned int busy_timeout_ms = 2000;
 18
 19module_param(busy_timeout_ms, uint, 0644);
 20MODULE_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
113struct 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
125static struct tpm_crb_ffa *tpm_crb_ffa;
126static struct ffa_driver tpm_crb_ffa_driver;
127
128static 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 */
178int tpm_crb_ffa_init(void)
179{
180	int ret = 0;
181
182	if (!IS_MODULE(CONFIG_TCG_ARM_CRB_FFA)) {
183		ret = ffa_register(&tpm_crb_ffa_driver);
184		if (ret) {
185			tpm_crb_ffa = ERR_PTR(-ENODEV);
186			return ret;
187		}
188	}
189
190	if (!tpm_crb_ffa)
191		ret = -ENOENT;
192
193	if (IS_ERR_VALUE(tpm_crb_ffa))
194		ret = -ENODEV;
195
196	return ret;
197}
198EXPORT_SYMBOL_GPL(tpm_crb_ffa_init);
199
200static int __tpm_crb_ffa_try_send_receive(unsigned long func_id,
201					  unsigned long a0, unsigned long a1,
202					  unsigned long a2)
203{
204	const struct ffa_msg_ops *msg_ops;
205	int ret;
206
207	msg_ops = tpm_crb_ffa->ffa_dev->ops->msg_ops;
208
209	if (ffa_partition_supports_direct_req2_recv(tpm_crb_ffa->ffa_dev)) {
210		tpm_crb_ffa->direct_msg_data2 = (struct ffa_send_direct_data2){
211			.data = { func_id, a0, a1, a2 },
212		};
213
214		ret = msg_ops->sync_send_receive2(tpm_crb_ffa->ffa_dev,
215				&tpm_crb_ffa->direct_msg_data2);
216		if (!ret)
217			ret = tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data2.data[0]);
218	} else {
219		tpm_crb_ffa->direct_msg_data = (struct ffa_send_direct_data){
220			.data1 = func_id,
221			.data2 = a0,
222			.data3 = a1,
223			.data4 = a2,
224		};
225
226		ret = msg_ops->sync_send_receive(tpm_crb_ffa->ffa_dev,
227				&tpm_crb_ffa->direct_msg_data);
228		if (!ret)
229			ret = tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data.data1);
230	}
231
232	return ret;
233}
234
235static int __tpm_crb_ffa_send_receive(unsigned long func_id, unsigned long a0,
236				      unsigned long a1, unsigned long a2)
237{
238	ktime_t start, stop;
239	int ret;
240
241	if (!tpm_crb_ffa)
242		return -ENOENT;
243
244	start = ktime_get();
245	stop = ktime_add(start, ms_to_ktime(busy_timeout_ms));
246
247	for (;;) {
248		ret = __tpm_crb_ffa_try_send_receive(func_id, a0, a1, a2);
249		if (ret != -EBUSY)
250			break;
251
252		usleep_range(50, 100);
253		if (ktime_after(ktime_get(), stop)) {
254			dev_warn(&tpm_crb_ffa->ffa_dev->dev,
255				 "Busy retry timed out\n");
256			break;
257		}
258	}
259
260	return ret;
261}
262
263/**
264 * tpm_crb_ffa_get_interface_version() - gets the ABI version of the TPM service
265 * @major: Pointer to caller-allocated buffer to hold the major version
266 *         number the ABI
267 * @minor: Pointer to caller-allocated buffer to hold the minor version
268 *         number the ABI
269 *
270 * Returns the major and minor version of the ABI of the FF-A based TPM.
271 * Allows the caller to evaluate its compatibility with the version of
272 * the ABI.
273 *
274 * Return: 0 on success, negative error code on failure.
275 */
276static int tpm_crb_ffa_get_interface_version(u16 *major, u16 *minor)
277{
278	int rc;
279
280	if (!tpm_crb_ffa)
281		return -ENOENT;
282
283	if (IS_ERR_VALUE(tpm_crb_ffa))
284		return -ENODEV;
285
286	if (!major || !minor)
287		return -EINVAL;
288
289	guard(mutex)(&tpm_crb_ffa->msg_data_lock);
290
291	rc = __tpm_crb_ffa_send_receive(CRB_FFA_GET_INTERFACE_VERSION, 0x00, 0x00, 0x00);
292	if (!rc) {
293		if (ffa_partition_supports_direct_req2_recv(tpm_crb_ffa->ffa_dev)) {
294			*major = CRB_FFA_MAJOR_VERSION(tpm_crb_ffa->direct_msg_data2.data[1]);
295			*minor = CRB_FFA_MINOR_VERSION(tpm_crb_ffa->direct_msg_data2.data[1]);
296		} else {
297			*major = CRB_FFA_MAJOR_VERSION(tpm_crb_ffa->direct_msg_data.data2);
298			*minor = CRB_FFA_MINOR_VERSION(tpm_crb_ffa->direct_msg_data.data2);
299		}
300	}
301
302	return rc;
303}
304
305/**
306 * tpm_crb_ffa_start() - signals the TPM that a field has changed in the CRB
307 * @request_type: Identifies whether the change to the CRB is in the command
308 *                fields or locality fields.
309 * @locality: Specifies the locality number.
310 *
311 * Used by the CRB driver
312 * that might be useful to those using or modifying it.  Begins with
313 * empty comment line, and may include additional embedded empty
314 * comment lines.
315 *
316 * Return: 0 on success, negative error code on failure.
317 */
318int tpm_crb_ffa_start(int request_type, int locality)
319{
320	if (!tpm_crb_ffa)
321		return -ENOENT;
322
323	if (IS_ERR_VALUE(tpm_crb_ffa))
324		return -ENODEV;
325
326	guard(mutex)(&tpm_crb_ffa->msg_data_lock);
327
328	return __tpm_crb_ffa_send_receive(CRB_FFA_START, request_type, locality, 0x00);
329}
330EXPORT_SYMBOL_GPL(tpm_crb_ffa_start);
331
332static int tpm_crb_ffa_probe(struct ffa_device *ffa_dev)
333{
334	struct tpm_crb_ffa *p;
335	int rc;
336
337	/* only one instance of a TPM partition is supported */
338	if (tpm_crb_ffa && !IS_ERR_VALUE(tpm_crb_ffa))
339		return -EEXIST;
340
341	tpm_crb_ffa = ERR_PTR(-ENODEV); // set tpm_crb_ffa so we can detect probe failure
342
343	if (!ffa_partition_supports_direct_recv(ffa_dev) &&
344	    !ffa_partition_supports_direct_req2_recv(ffa_dev)) {
345		dev_warn(&ffa_dev->dev, "partition doesn't support direct message receive.\n");
346		return -EINVAL;
347	}
348
349	p = kzalloc(sizeof(*tpm_crb_ffa), GFP_KERNEL);
350	if (!p)
351		return -ENOMEM;
352	tpm_crb_ffa = p;
353
354	mutex_init(&tpm_crb_ffa->msg_data_lock);
355	tpm_crb_ffa->ffa_dev = ffa_dev;
356	ffa_dev_set_drvdata(ffa_dev, tpm_crb_ffa);
357
358	/* if TPM is aarch32 use 32-bit SMCs */
359	if (!ffa_partition_check_property(ffa_dev, FFA_PARTITION_AARCH64_EXEC))
360		ffa_dev->ops->msg_ops->mode_32bit_set(ffa_dev);
361
362	/* verify compatibility of TPM service version number */
363	rc = tpm_crb_ffa_get_interface_version(&tpm_crb_ffa->major_version,
364					       &tpm_crb_ffa->minor_version);
365	if (rc) {
366		dev_err(&ffa_dev->dev, "failed to get crb interface version. rc:%d\n", rc);
367		goto out;
368	}
369
370	dev_info(&ffa_dev->dev, "ABI version %u.%u\n", tpm_crb_ffa->major_version,
371		tpm_crb_ffa->minor_version);
372
373	if (tpm_crb_ffa->major_version != CRB_FFA_VERSION_MAJOR ||
374	    (tpm_crb_ffa->minor_version > 0 &&
375	    tpm_crb_ffa->minor_version < CRB_FFA_VERSION_MINOR)) {
376		dev_warn(&ffa_dev->dev, "Incompatible ABI version\n");
377		goto out;
378	}
379
380	return 0;
381
382out:
383	kfree(tpm_crb_ffa);
384	tpm_crb_ffa = ERR_PTR(-ENODEV);
385	return -EINVAL;
386}
387
388static void tpm_crb_ffa_remove(struct ffa_device *ffa_dev)
389{
390	kfree(tpm_crb_ffa);
391	tpm_crb_ffa = NULL;
392}
393
394static const struct ffa_device_id tpm_crb_ffa_device_id[] = {
395	/* 17b862a4-1806-4faf-86b3-089a58353861 */
396	{ UUID_INIT(0x17b862a4, 0x1806, 0x4faf,
397		    0x86, 0xb3, 0x08, 0x9a, 0x58, 0x35, 0x38, 0x61) },
398	{}
399};
400
401static struct ffa_driver tpm_crb_ffa_driver = {
402	.name = "ffa-crb",
403	.probe = tpm_crb_ffa_probe,
404	.remove = tpm_crb_ffa_remove,
405	.id_table = tpm_crb_ffa_device_id,
406};
407
408#ifdef MODULE
409module_ffa_driver(tpm_crb_ffa_driver);
410#endif
411
412MODULE_AUTHOR("Arm");
413MODULE_DESCRIPTION("TPM CRB FFA driver");
414MODULE_LICENSE("GPL");