1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2015 Infineon Technologies AG
4  * Copyright (C) 2016 STMicroelectronics SAS
5  *
6  * Authors:
7  * Peter Huewe <peter.huewe@infineon.com>
8  * Christophe Ricard <christophe-h.ricard@st.com>
9  *
10  * Maintained by: <tpmdd-devel@lists.sourceforge.net>
11  *
12  * Device driver for TCG/TCPA TPM (trusted platform module).
13  * Specifications at www.trustedcomputinggroup.org
14  *
15  * This device driver implements the TPM interface as defined in
16  * the TCG TPM Interface Spec version 1.3, revision 27 via _raw/native
17  * SPI access_.
18  *
19  * It is based on the original tpm_tis device driver from Leendert van
20  * Dorn and Kyleen Hall and Jarko Sakkinnen.
21  */
22 
23 #include <linux/acpi.h>
24 #include <linux/completion.h>
25 #include <linux/init.h>
26 #include <linux/interrupt.h>
27 #include <linux/kernel.h>
28 #include <linux/module.h>
29 #include <linux/slab.h>
30 
31 #include <linux/of_device.h>
32 #include <linux/spi/spi.h>
33 #include <linux/tpm.h>
34 
35 #include "tpm.h"
36 #include "tpm_tis_core.h"
37 #include "tpm_tis_spi.h"
38 
39 #define MAX_SPI_FRAMESIZE 64
40 
41 /*
42  * TCG SPI flow control is documented in section 6.4 of the spec[1]. In short,
43  * keep trying to read from the device until MISO goes high indicating the
44  * wait state has ended.
45  *
46  * [1] https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/
47  */
tpm_tis_spi_flow_control(struct tpm_tis_spi_phy * phy,struct spi_transfer * spi_xfer)48 static int tpm_tis_spi_flow_control(struct tpm_tis_spi_phy *phy,
49 				    struct spi_transfer *spi_xfer)
50 {
51 	struct spi_message m;
52 	int ret, i;
53 
54 	if ((phy->iobuf[3] & 0x01) == 0) {
55 		// handle SPI wait states
56 		for (i = 0; i < TPM_RETRY; i++) {
57 			spi_xfer->len = 1;
58 			spi_message_init(&m);
59 			spi_message_add_tail(spi_xfer, &m);
60 			ret = spi_sync_locked(phy->spi_device, &m);
61 			if (ret < 0)
62 				return ret;
63 			if (phy->iobuf[0] & 0x01)
64 				break;
65 		}
66 
67 		if (i == TPM_RETRY)
68 			return -ETIMEDOUT;
69 	}
70 
71 	return 0;
72 }
73 
tpm_tis_spi_transfer(struct tpm_tis_data * data,u32 addr,u16 len,u8 * in,const u8 * out)74 int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
75 			 u8 *in, const u8 *out)
76 {
77 	struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
78 	int ret = 0;
79 	struct spi_message m;
80 	struct spi_transfer spi_xfer;
81 	u8 transfer_len;
82 
83 	spi_bus_lock(phy->spi_device->master);
84 
85 	while (len) {
86 		transfer_len = min_t(u16, len, MAX_SPI_FRAMESIZE);
87 
88 		phy->iobuf[0] = (in ? 0x80 : 0) | (transfer_len - 1);
89 		phy->iobuf[1] = 0xd4;
90 		phy->iobuf[2] = addr >> 8;
91 		phy->iobuf[3] = addr;
92 
93 		memset(&spi_xfer, 0, sizeof(spi_xfer));
94 		spi_xfer.tx_buf = phy->iobuf;
95 		spi_xfer.rx_buf = phy->iobuf;
96 		spi_xfer.len = 4;
97 		spi_xfer.cs_change = 1;
98 
99 		spi_message_init(&m);
100 		spi_message_add_tail(&spi_xfer, &m);
101 		ret = spi_sync_locked(phy->spi_device, &m);
102 		if (ret < 0)
103 			goto exit;
104 
105 		/* Flow control transfers are receive only */
106 		spi_xfer.tx_buf = NULL;
107 		ret = phy->flow_control(phy, &spi_xfer);
108 		if (ret < 0)
109 			goto exit;
110 
111 		spi_xfer.cs_change = 0;
112 		spi_xfer.len = transfer_len;
113 		spi_xfer.delay.value = 5;
114 		spi_xfer.delay.unit = SPI_DELAY_UNIT_USECS;
115 
116 		if (out) {
117 			spi_xfer.tx_buf = phy->iobuf;
118 			spi_xfer.rx_buf = NULL;
119 			memcpy(phy->iobuf, out, transfer_len);
120 			out += transfer_len;
121 		}
122 
123 		spi_message_init(&m);
124 		spi_message_add_tail(&spi_xfer, &m);
125 		reinit_completion(&phy->ready);
126 		ret = spi_sync_locked(phy->spi_device, &m);
127 		if (ret < 0)
128 			goto exit;
129 
130 		if (in) {
131 			memcpy(in, phy->iobuf, transfer_len);
132 			in += transfer_len;
133 		}
134 
135 		len -= transfer_len;
136 	}
137 
138 exit:
139 	spi_bus_unlock(phy->spi_device->master);
140 	return ret;
141 }
142 
tpm_tis_spi_read_bytes(struct tpm_tis_data * data,u32 addr,u16 len,u8 * result)143 static int tpm_tis_spi_read_bytes(struct tpm_tis_data *data, u32 addr,
144 				  u16 len, u8 *result)
145 {
146 	return tpm_tis_spi_transfer(data, addr, len, result, NULL);
147 }
148 
tpm_tis_spi_write_bytes(struct tpm_tis_data * data,u32 addr,u16 len,const u8 * value)149 static int tpm_tis_spi_write_bytes(struct tpm_tis_data *data, u32 addr,
150 				   u16 len, const u8 *value)
151 {
152 	return tpm_tis_spi_transfer(data, addr, len, NULL, value);
153 }
154 
tpm_tis_spi_read16(struct tpm_tis_data * data,u32 addr,u16 * result)155 int tpm_tis_spi_read16(struct tpm_tis_data *data, u32 addr, u16 *result)
156 {
157 	__le16 result_le;
158 	int rc;
159 
160 	rc = data->phy_ops->read_bytes(data, addr, sizeof(u16),
161 				       (u8 *)&result_le);
162 	if (!rc)
163 		*result = le16_to_cpu(result_le);
164 
165 	return rc;
166 }
167 
tpm_tis_spi_read32(struct tpm_tis_data * data,u32 addr,u32 * result)168 int tpm_tis_spi_read32(struct tpm_tis_data *data, u32 addr, u32 *result)
169 {
170 	__le32 result_le;
171 	int rc;
172 
173 	rc = data->phy_ops->read_bytes(data, addr, sizeof(u32),
174 				       (u8 *)&result_le);
175 	if (!rc)
176 		*result = le32_to_cpu(result_le);
177 
178 	return rc;
179 }
180 
tpm_tis_spi_write32(struct tpm_tis_data * data,u32 addr,u32 value)181 int tpm_tis_spi_write32(struct tpm_tis_data *data, u32 addr, u32 value)
182 {
183 	__le32 value_le;
184 	int rc;
185 
186 	value_le = cpu_to_le32(value);
187 	rc = data->phy_ops->write_bytes(data, addr, sizeof(u32),
188 					(u8 *)&value_le);
189 
190 	return rc;
191 }
192 
tpm_tis_spi_init(struct spi_device * spi,struct tpm_tis_spi_phy * phy,int irq,const struct tpm_tis_phy_ops * phy_ops)193 int tpm_tis_spi_init(struct spi_device *spi, struct tpm_tis_spi_phy *phy,
194 		     int irq, const struct tpm_tis_phy_ops *phy_ops)
195 {
196 	phy->iobuf = devm_kmalloc(&spi->dev, MAX_SPI_FRAMESIZE, GFP_KERNEL);
197 	if (!phy->iobuf)
198 		return -ENOMEM;
199 
200 	phy->spi_device = spi;
201 
202 	return tpm_tis_core_init(&spi->dev, &phy->priv, irq, phy_ops, NULL);
203 }
204 
205 static const struct tpm_tis_phy_ops tpm_spi_phy_ops = {
206 	.read_bytes = tpm_tis_spi_read_bytes,
207 	.write_bytes = tpm_tis_spi_write_bytes,
208 	.read16 = tpm_tis_spi_read16,
209 	.read32 = tpm_tis_spi_read32,
210 	.write32 = tpm_tis_spi_write32,
211 };
212 
tpm_tis_spi_probe(struct spi_device * dev)213 static int tpm_tis_spi_probe(struct spi_device *dev)
214 {
215 	struct tpm_tis_spi_phy *phy;
216 	int irq;
217 
218 	phy = devm_kzalloc(&dev->dev, sizeof(struct tpm_tis_spi_phy),
219 			   GFP_KERNEL);
220 	if (!phy)
221 		return -ENOMEM;
222 
223 	phy->flow_control = tpm_tis_spi_flow_control;
224 
225 	/* If the SPI device has an IRQ then use that */
226 	if (dev->irq > 0)
227 		irq = dev->irq;
228 	else
229 		irq = -1;
230 
231 	init_completion(&phy->ready);
232 	return tpm_tis_spi_init(dev, phy, irq, &tpm_spi_phy_ops);
233 }
234 
235 typedef int (*tpm_tis_spi_probe_func)(struct spi_device *);
236 
tpm_tis_spi_driver_probe(struct spi_device * spi)237 static int tpm_tis_spi_driver_probe(struct spi_device *spi)
238 {
239 	const struct spi_device_id *spi_dev_id = spi_get_device_id(spi);
240 	tpm_tis_spi_probe_func probe_func;
241 
242 	probe_func = of_device_get_match_data(&spi->dev);
243 	if (!probe_func) {
244 		if (spi_dev_id) {
245 			probe_func = (tpm_tis_spi_probe_func)spi_dev_id->driver_data;
246 			if (!probe_func)
247 				return -ENODEV;
248 		} else
249 			probe_func = tpm_tis_spi_probe;
250 	}
251 
252 	return probe_func(spi);
253 }
254 
255 static SIMPLE_DEV_PM_OPS(tpm_tis_pm, tpm_pm_suspend, tpm_tis_spi_resume);
256 
tpm_tis_spi_remove(struct spi_device * dev)257 static int tpm_tis_spi_remove(struct spi_device *dev)
258 {
259 	struct tpm_chip *chip = spi_get_drvdata(dev);
260 
261 	tpm_chip_unregister(chip);
262 	tpm_tis_remove(chip);
263 	return 0;
264 }
265 
266 static const struct spi_device_id tpm_tis_spi_id[] = {
267 	{ "st33htpm-spi", (unsigned long)tpm_tis_spi_probe },
268 	{ "slb9670", (unsigned long)tpm_tis_spi_probe },
269 	{ "tpm_tis_spi", (unsigned long)tpm_tis_spi_probe },
270 	{ "tpm_tis-spi", (unsigned long)tpm_tis_spi_probe },
271 	{ "cr50", (unsigned long)cr50_spi_probe },
272 	{}
273 };
274 MODULE_DEVICE_TABLE(spi, tpm_tis_spi_id);
275 
276 static const struct of_device_id of_tis_spi_match[] = {
277 	{ .compatible = "st,st33htpm-spi", .data = tpm_tis_spi_probe },
278 	{ .compatible = "infineon,slb9670", .data = tpm_tis_spi_probe },
279 	{ .compatible = "tcg,tpm_tis-spi", .data = tpm_tis_spi_probe },
280 	{ .compatible = "google,cr50", .data = cr50_spi_probe },
281 	{}
282 };
283 MODULE_DEVICE_TABLE(of, of_tis_spi_match);
284 
285 static const struct acpi_device_id acpi_tis_spi_match[] = {
286 	{"SMO0768", 0},
287 	{}
288 };
289 MODULE_DEVICE_TABLE(acpi, acpi_tis_spi_match);
290 
291 static struct spi_driver tpm_tis_spi_driver = {
292 	.driver = {
293 		.name = "tpm_tis_spi",
294 		.pm = &tpm_tis_pm,
295 		.of_match_table = of_match_ptr(of_tis_spi_match),
296 		.acpi_match_table = ACPI_PTR(acpi_tis_spi_match),
297 		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
298 	},
299 	.probe = tpm_tis_spi_driver_probe,
300 	.remove = tpm_tis_spi_remove,
301 	.id_table = tpm_tis_spi_id,
302 };
303 module_spi_driver(tpm_tis_spi_driver);
304 
305 MODULE_DESCRIPTION("TPM Driver for native SPI access");
306 MODULE_LICENSE("GPL");
307