Commit | Line | Data |
---|---|---|
bbc23a07 AS |
1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* | |
3 | * Copyright (c) 2014-2021 Nuvoton Technology corporation | |
4 | * Copyright (C) 2019-2022 Infineon Technologies AG | |
5 | * | |
6 | * This device driver implements the TPM interface as defined in the TCG PC | |
7 | * Client Platform TPM Profile (PTP) Specification for TPM 2.0 v1.04 | |
8 | * Revision 14. | |
9 | * | |
10 | * It is based on the tpm_tis_spi device driver. | |
11 | */ | |
12 | ||
13 | #include <linux/i2c.h> | |
14 | #include <linux/crc-ccitt.h> | |
15 | #include "tpm_tis_core.h" | |
16 | ||
17 | /* TPM registers */ | |
18 | #define TPM_I2C_LOC_SEL 0x00 | |
19 | #define TPM_I2C_ACCESS 0x04 | |
20 | #define TPM_I2C_INTERFACE_CAPABILITY 0x30 | |
21 | #define TPM_I2C_DEVICE_ADDRESS 0x38 | |
22 | #define TPM_I2C_DATA_CSUM_ENABLE 0x40 | |
23 | #define TPM_DATA_CSUM 0x44 | |
24 | #define TPM_I2C_DID_VID 0x48 | |
25 | #define TPM_I2C_RID 0x4C | |
26 | ||
27 | /* TIS-compatible register address to avoid clash with TPM_ACCESS (0x00) */ | |
28 | #define TPM_LOC_SEL 0x0FFF | |
29 | ||
30 | /* Mask to extract the I2C register from TIS register addresses */ | |
31 | #define TPM_TIS_REGISTER_MASK 0x0FFF | |
32 | ||
33 | /* Default Guard Time of 250µs until interface capability register is read */ | |
34 | #define GUARD_TIME_DEFAULT_MIN 250 | |
35 | #define GUARD_TIME_DEFAULT_MAX 300 | |
36 | ||
37 | /* Guard Time of 250µs after I2C slave NACK */ | |
38 | #define GUARD_TIME_ERR_MIN 250 | |
39 | #define GUARD_TIME_ERR_MAX 300 | |
40 | ||
41 | /* Guard Time bit masks; SR is repeated start, RW is read then write, etc. */ | |
42 | #define TPM_GUARD_TIME_SR_MASK 0x40000000 | |
43 | #define TPM_GUARD_TIME_RR_MASK 0x00100000 | |
44 | #define TPM_GUARD_TIME_RW_MASK 0x00080000 | |
45 | #define TPM_GUARD_TIME_WR_MASK 0x00040000 | |
46 | #define TPM_GUARD_TIME_WW_MASK 0x00020000 | |
47 | #define TPM_GUARD_TIME_MIN_MASK 0x0001FE00 | |
48 | #define TPM_GUARD_TIME_MIN_SHIFT 9 | |
49 | ||
50 | /* Masks with bits that must be read zero */ | |
51 | #define TPM_ACCESS_READ_ZERO 0x48 | |
561d6ef7 | 52 | #define TPM_INT_ENABLE_ZERO 0x7FFFFF60 |
bbc23a07 AS |
53 | #define TPM_STS_READ_ZERO 0x23 |
54 | #define TPM_INTF_CAPABILITY_ZERO 0x0FFFF000 | |
55 | #define TPM_I2C_INTERFACE_CAPABILITY_ZERO 0x80000000 | |
56 | ||
57 | struct tpm_tis_i2c_phy { | |
58 | struct tpm_tis_data priv; | |
59 | struct i2c_client *i2c_client; | |
60 | bool guard_time_read; | |
61 | bool guard_time_write; | |
62 | u16 guard_time_min; | |
63 | u16 guard_time_max; | |
64 | u8 *io_buf; | |
65 | }; | |
66 | ||
67 | static inline struct tpm_tis_i2c_phy * | |
68 | to_tpm_tis_i2c_phy(struct tpm_tis_data *data) | |
69 | { | |
70 | return container_of(data, struct tpm_tis_i2c_phy, priv); | |
71 | } | |
72 | ||
73 | /* | |
74 | * tpm_tis_core uses the register addresses as defined in Table 19 "Allocation | |
75 | * of Register Space for FIFO TPM Access" of the TCG PC Client PTP | |
76 | * Specification. In order for this code to work together with tpm_tis_core, | |
77 | * those addresses need to mapped to the registers defined for I2C TPMs in | |
78 | * Table 51 "I2C-TPM Register Overview". | |
79 | * | |
80 | * For most addresses this can be done by simply stripping off the locality | |
81 | * information from the address. A few addresses need to be mapped explicitly, | |
82 | * since the corresponding I2C registers have been moved around. TPM_LOC_SEL is | |
83 | * only defined for I2C TPMs and is also mapped explicitly here to distinguish | |
84 | * it from TPM_ACCESS(0). | |
85 | * | |
86 | * Locality information is ignored, since this driver assumes exclusive access | |
87 | * to the TPM and always uses locality 0. | |
88 | */ | |
89 | static u8 tpm_tis_i2c_address_to_register(u32 addr) | |
90 | { | |
91 | addr &= TPM_TIS_REGISTER_MASK; | |
92 | ||
93 | switch (addr) { | |
94 | case TPM_ACCESS(0): | |
95 | return TPM_I2C_ACCESS; | |
96 | case TPM_LOC_SEL: | |
97 | return TPM_I2C_LOC_SEL; | |
98 | case TPM_DID_VID(0): | |
99 | return TPM_I2C_DID_VID; | |
100 | case TPM_RID(0): | |
101 | return TPM_I2C_RID; | |
102 | default: | |
103 | return addr; | |
104 | } | |
105 | } | |
106 | ||
107 | static int tpm_tis_i2c_retry_transfer_until_ack(struct tpm_tis_data *data, | |
108 | struct i2c_msg *msg) | |
109 | { | |
110 | struct tpm_tis_i2c_phy *phy = to_tpm_tis_i2c_phy(data); | |
111 | bool guard_time; | |
112 | int i = 0; | |
113 | int ret; | |
114 | ||
115 | if (msg->flags & I2C_M_RD) | |
116 | guard_time = phy->guard_time_read; | |
117 | else | |
118 | guard_time = phy->guard_time_write; | |
119 | ||
120 | do { | |
121 | ret = i2c_transfer(phy->i2c_client->adapter, msg, 1); | |
122 | if (ret < 0) | |
123 | usleep_range(GUARD_TIME_ERR_MIN, GUARD_TIME_ERR_MAX); | |
124 | else if (guard_time) | |
125 | usleep_range(phy->guard_time_min, phy->guard_time_max); | |
126 | /* retry on TPM NACK */ | |
127 | } while (ret < 0 && i++ < TPM_RETRY); | |
128 | ||
129 | return ret; | |
130 | } | |
131 | ||
132 | /* Check that bits which must be read zero are not set */ | |
133 | static int tpm_tis_i2c_sanity_check_read(u8 reg, u16 len, u8 *buf) | |
134 | { | |
135 | u32 zero_mask; | |
136 | u32 value; | |
137 | ||
138 | switch (len) { | |
139 | case sizeof(u8): | |
140 | value = buf[0]; | |
141 | break; | |
142 | case sizeof(u16): | |
143 | value = le16_to_cpup((__le16 *)buf); | |
144 | break; | |
145 | case sizeof(u32): | |
146 | value = le32_to_cpup((__le32 *)buf); | |
147 | break; | |
148 | default: | |
149 | /* unknown length, skip check */ | |
150 | return 0; | |
151 | } | |
152 | ||
153 | switch (reg) { | |
154 | case TPM_I2C_ACCESS: | |
155 | zero_mask = TPM_ACCESS_READ_ZERO; | |
156 | break; | |
157 | case TPM_INT_ENABLE(0) & TPM_TIS_REGISTER_MASK: | |
158 | zero_mask = TPM_INT_ENABLE_ZERO; | |
159 | break; | |
160 | case TPM_STS(0) & TPM_TIS_REGISTER_MASK: | |
161 | zero_mask = TPM_STS_READ_ZERO; | |
162 | break; | |
163 | case TPM_INTF_CAPS(0) & TPM_TIS_REGISTER_MASK: | |
164 | zero_mask = TPM_INTF_CAPABILITY_ZERO; | |
165 | break; | |
166 | case TPM_I2C_INTERFACE_CAPABILITY: | |
167 | zero_mask = TPM_I2C_INTERFACE_CAPABILITY_ZERO; | |
168 | break; | |
169 | default: | |
170 | /* unknown register, skip check */ | |
171 | return 0; | |
172 | } | |
173 | ||
174 | if (unlikely((value & zero_mask) != 0x00)) { | |
175 | pr_debug("TPM I2C read of register 0x%02x failed sanity check: 0x%x\n", reg, value); | |
176 | return -EIO; | |
177 | } | |
178 | ||
179 | return 0; | |
180 | } | |
181 | ||
182 | static int tpm_tis_i2c_read_bytes(struct tpm_tis_data *data, u32 addr, u16 len, | |
183 | u8 *result, enum tpm_tis_io_mode io_mode) | |
184 | { | |
185 | struct tpm_tis_i2c_phy *phy = to_tpm_tis_i2c_phy(data); | |
186 | struct i2c_msg msg = { .addr = phy->i2c_client->addr }; | |
187 | u8 reg = tpm_tis_i2c_address_to_register(addr); | |
188 | int i; | |
189 | int ret; | |
190 | ||
191 | for (i = 0; i < TPM_RETRY; i++) { | |
192 | /* write register */ | |
193 | msg.len = sizeof(reg); | |
194 | msg.buf = ® | |
195 | msg.flags = 0; | |
196 | ret = tpm_tis_i2c_retry_transfer_until_ack(data, &msg); | |
197 | if (ret < 0) | |
198 | return ret; | |
199 | ||
200 | /* read data */ | |
201 | msg.buf = result; | |
202 | msg.len = len; | |
203 | msg.flags = I2C_M_RD; | |
204 | ret = tpm_tis_i2c_retry_transfer_until_ack(data, &msg); | |
205 | if (ret < 0) | |
206 | return ret; | |
207 | ||
208 | ret = tpm_tis_i2c_sanity_check_read(reg, len, result); | |
209 | if (ret == 0) | |
210 | return 0; | |
211 | ||
212 | usleep_range(GUARD_TIME_ERR_MIN, GUARD_TIME_ERR_MAX); | |
213 | } | |
214 | ||
215 | return ret; | |
216 | } | |
217 | ||
218 | static int tpm_tis_i2c_write_bytes(struct tpm_tis_data *data, u32 addr, u16 len, | |
219 | const u8 *value, | |
220 | enum tpm_tis_io_mode io_mode) | |
221 | { | |
222 | struct tpm_tis_i2c_phy *phy = to_tpm_tis_i2c_phy(data); | |
223 | struct i2c_msg msg = { .addr = phy->i2c_client->addr }; | |
224 | u8 reg = tpm_tis_i2c_address_to_register(addr); | |
225 | int ret; | |
226 | ||
227 | if (len > TPM_BUFSIZE - 1) | |
228 | return -EIO; | |
229 | ||
230 | /* write register and data in one go */ | |
231 | phy->io_buf[0] = reg; | |
232 | memcpy(phy->io_buf + sizeof(reg), value, len); | |
233 | ||
234 | msg.len = sizeof(reg) + len; | |
235 | msg.buf = phy->io_buf; | |
236 | ret = tpm_tis_i2c_retry_transfer_until_ack(data, &msg); | |
237 | if (ret < 0) | |
238 | return ret; | |
239 | ||
240 | return 0; | |
241 | } | |
242 | ||
243 | static int tpm_tis_i2c_verify_crc(struct tpm_tis_data *data, size_t len, | |
244 | const u8 *value) | |
245 | { | |
246 | u16 crc_tpm, crc_host; | |
247 | int rc; | |
248 | ||
249 | rc = tpm_tis_read16(data, TPM_DATA_CSUM, &crc_tpm); | |
250 | if (rc < 0) | |
251 | return rc; | |
252 | ||
253 | /* reflect crc result, regardless of host endianness */ | |
254 | crc_host = swab16(crc_ccitt(0, value, len)); | |
255 | if (crc_tpm != crc_host) | |
256 | return -EIO; | |
257 | ||
258 | return 0; | |
259 | } | |
260 | ||
261 | /* | |
262 | * Guard Time: | |
263 | * After each I2C operation, the TPM might require the master to wait. | |
264 | * The time period is vendor-specific and must be read from the | |
265 | * TPM_I2C_INTERFACE_CAPABILITY register. | |
266 | * | |
267 | * Before the Guard Time is read (or after the TPM failed to send an I2C NACK), | |
268 | * a Guard Time of 250µs applies. | |
269 | * | |
270 | * Various flags in the same register indicate if a guard time is needed: | |
271 | * - SR: <I2C read with repeated start> <guard time> <I2C read> | |
272 | * - RR: <I2C read> <guard time> <I2C read> | |
273 | * - RW: <I2C read> <guard time> <I2C write> | |
274 | * - WR: <I2C write> <guard time> <I2C read> | |
275 | * - WW: <I2C write> <guard time> <I2C write> | |
276 | * | |
277 | * See TCG PC Client PTP Specification v1.04, 8.1.10 GUARD_TIME | |
278 | */ | |
279 | static int tpm_tis_i2c_init_guard_time(struct tpm_tis_i2c_phy *phy) | |
280 | { | |
281 | u32 i2c_caps; | |
282 | int ret; | |
283 | ||
284 | phy->guard_time_read = true; | |
285 | phy->guard_time_write = true; | |
286 | phy->guard_time_min = GUARD_TIME_DEFAULT_MIN; | |
287 | phy->guard_time_max = GUARD_TIME_DEFAULT_MAX; | |
288 | ||
289 | ret = tpm_tis_i2c_read_bytes(&phy->priv, TPM_I2C_INTERFACE_CAPABILITY, | |
290 | sizeof(i2c_caps), (u8 *)&i2c_caps, | |
291 | TPM_TIS_PHYS_32); | |
292 | if (ret) | |
293 | return ret; | |
294 | ||
295 | phy->guard_time_read = (i2c_caps & TPM_GUARD_TIME_RR_MASK) || | |
296 | (i2c_caps & TPM_GUARD_TIME_RW_MASK); | |
297 | phy->guard_time_write = (i2c_caps & TPM_GUARD_TIME_WR_MASK) || | |
298 | (i2c_caps & TPM_GUARD_TIME_WW_MASK); | |
299 | phy->guard_time_min = (i2c_caps & TPM_GUARD_TIME_MIN_MASK) >> | |
300 | TPM_GUARD_TIME_MIN_SHIFT; | |
301 | /* guard_time_max = guard_time_min * 1.2 */ | |
302 | phy->guard_time_max = phy->guard_time_min + phy->guard_time_min / 5; | |
303 | ||
304 | return 0; | |
305 | } | |
306 | ||
307 | static SIMPLE_DEV_PM_OPS(tpm_tis_pm, tpm_pm_suspend, tpm_tis_resume); | |
308 | ||
309 | static const struct tpm_tis_phy_ops tpm_i2c_phy_ops = { | |
310 | .read_bytes = tpm_tis_i2c_read_bytes, | |
311 | .write_bytes = tpm_tis_i2c_write_bytes, | |
312 | .verify_crc = tpm_tis_i2c_verify_crc, | |
313 | }; | |
314 | ||
40078327 | 315 | static int tpm_tis_i2c_probe(struct i2c_client *dev) |
bbc23a07 AS |
316 | { |
317 | struct tpm_tis_i2c_phy *phy; | |
318 | const u8 crc_enable = 1; | |
319 | const u8 locality = 0; | |
320 | int ret; | |
321 | ||
322 | phy = devm_kzalloc(&dev->dev, sizeof(struct tpm_tis_i2c_phy), | |
323 | GFP_KERNEL); | |
324 | if (!phy) | |
325 | return -ENOMEM; | |
326 | ||
327 | phy->io_buf = devm_kzalloc(&dev->dev, TPM_BUFSIZE, GFP_KERNEL); | |
328 | if (!phy->io_buf) | |
329 | return -ENOMEM; | |
330 | ||
7bfda9c7 | 331 | set_bit(TPM_TIS_DEFAULT_CANCELLATION, &phy->priv.flags); |
bbc23a07 AS |
332 | phy->i2c_client = dev; |
333 | ||
334 | /* must precede all communication with the tpm */ | |
335 | ret = tpm_tis_i2c_init_guard_time(phy); | |
336 | if (ret) | |
337 | return ret; | |
338 | ||
339 | ret = tpm_tis_i2c_write_bytes(&phy->priv, TPM_LOC_SEL, sizeof(locality), | |
340 | &locality, TPM_TIS_PHYS_8); | |
341 | if (ret) | |
342 | return ret; | |
343 | ||
344 | ret = tpm_tis_i2c_write_bytes(&phy->priv, TPM_I2C_DATA_CSUM_ENABLE, | |
345 | sizeof(crc_enable), &crc_enable, | |
346 | TPM_TIS_PHYS_8); | |
347 | if (ret) | |
348 | return ret; | |
349 | ||
350 | return tpm_tis_core_init(&dev->dev, &phy->priv, -1, &tpm_i2c_phy_ops, | |
351 | NULL); | |
352 | } | |
353 | ||
ed5c2f5f | 354 | static void tpm_tis_i2c_remove(struct i2c_client *client) |
bbc23a07 AS |
355 | { |
356 | struct tpm_chip *chip = i2c_get_clientdata(client); | |
357 | ||
358 | tpm_chip_unregister(chip); | |
359 | tpm_tis_remove(chip); | |
bbc23a07 AS |
360 | } |
361 | ||
362 | static const struct i2c_device_id tpm_tis_i2c_id[] = { | |
363 | { "tpm_tis_i2c", 0 }, | |
364 | {} | |
365 | }; | |
366 | MODULE_DEVICE_TABLE(i2c, tpm_tis_i2c_id); | |
367 | ||
368 | #ifdef CONFIG_OF | |
369 | static const struct of_device_id of_tis_i2c_match[] = { | |
370 | { .compatible = "infineon,slb9673", }, | |
371 | {} | |
372 | }; | |
373 | MODULE_DEVICE_TABLE(of, of_tis_i2c_match); | |
374 | #endif | |
375 | ||
376 | static struct i2c_driver tpm_tis_i2c_driver = { | |
377 | .driver = { | |
bbc23a07 AS |
378 | .name = "tpm_tis_i2c", |
379 | .pm = &tpm_tis_pm, | |
380 | .of_match_table = of_match_ptr(of_tis_i2c_match), | |
381 | }, | |
40078327 | 382 | .probe_new = tpm_tis_i2c_probe, |
bbc23a07 AS |
383 | .remove = tpm_tis_i2c_remove, |
384 | .id_table = tpm_tis_i2c_id, | |
385 | }; | |
386 | module_i2c_driver(tpm_tis_i2c_driver); | |
387 | ||
388 | MODULE_DESCRIPTION("TPM Driver for native I2C access"); | |
389 | MODULE_LICENSE("GPL"); |