blob: 95ce2e9ccdc6e2ec40c7d52b0f35d17ba260001e [file] [log] [blame]
Jason Gunthorpea2871c62013-10-06 12:43:36 -06001/*
2 * ATMEL I2C TPM AT97SC3204T
3 *
4 * Copyright (C) 2012 V Lab Technologies
5 * Teddy Reed <teddy@prosauce.org>
6 * Copyright (C) 2013, Obsidian Research Corp.
7 * Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
8 * Device driver for ATMEL I2C TPMs.
9 *
10 * Teddy Reed determined the basic I2C command flow, unlike other I2C TPM
11 * devices the raw TCG formatted TPM command data is written via I2C and then
12 * raw TCG formatted TPM command data is returned via I2C.
13 *
14 * TGC status/locality/etc functions seen in the LPC implementation do not
15 * seem to be present.
16 *
17 * This program is free software: you can redistribute it and/or modify
18 * it under the terms of the GNU General Public License as published by
19 * the Free Software Foundation, either version 2 of the License, or
20 * (at your option) any later version.
21 *
22 * This program is distributed in the hope that it will be useful,
23 * but WITHOUT ANY WARRANTY; without even the implied warranty of
24 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
25 * GNU General Public License for more details.
26 *
27 * You should have received a copy of the GNU General Public License
28 * along with this program. If not, see http://www.gnu.org/licenses/>.
29 */
30#include <linux/init.h>
31#include <linux/module.h>
32#include <linux/moduleparam.h>
33#include <linux/slab.h>
34#include <linux/i2c.h>
35#include "tpm.h"
36
37#define I2C_DRIVER_NAME "tpm_i2c_atmel"
38
39#define TPM_I2C_SHORT_TIMEOUT 750 /* ms */
40#define TPM_I2C_LONG_TIMEOUT 2000 /* 2 sec */
41
42#define ATMEL_STS_OK 1
43
44struct priv_data {
45 size_t len;
46 /* This is the amount we read on the first try. 25 was chosen to fit a
47 * fair number of read responses in the buffer so a 2nd retry can be
48 * avoided in small message cases. */
49 u8 buffer[sizeof(struct tpm_output_header) + 25];
50};
51
52static int i2c_atmel_send(struct tpm_chip *chip, u8 *buf, size_t len)
53{
Christophe Ricard9e0d39d2016-03-31 22:57:00 +020054 struct priv_data *priv = dev_get_drvdata(&chip->dev);
Jason Gunthorpe8cfffc92016-02-29 12:29:47 -050055 struct i2c_client *client = to_i2c_client(chip->dev.parent);
Jason Gunthorpea2871c62013-10-06 12:43:36 -060056 s32 status;
57
58 priv->len = 0;
59
60 if (len <= 2)
61 return -EIO;
62
63 status = i2c_master_send(client, buf, len);
64
Jason Gunthorpe8cfffc92016-02-29 12:29:47 -050065 dev_dbg(&chip->dev,
Jason Gunthorpea2871c62013-10-06 12:43:36 -060066 "%s(buf=%*ph len=%0zx) -> sts=%d\n", __func__,
67 (int)min_t(size_t, 64, len), buf, len, status);
68 return status;
69}
70
71static int i2c_atmel_recv(struct tpm_chip *chip, u8 *buf, size_t count)
72{
Christophe Ricard9e0d39d2016-03-31 22:57:00 +020073 struct priv_data *priv = dev_get_drvdata(&chip->dev);
Jason Gunthorpe8cfffc92016-02-29 12:29:47 -050074 struct i2c_client *client = to_i2c_client(chip->dev.parent);
Jason Gunthorpea2871c62013-10-06 12:43:36 -060075 struct tpm_output_header *hdr =
76 (struct tpm_output_header *)priv->buffer;
77 u32 expected_len;
78 int rc;
79
80 if (priv->len == 0)
81 return -EIO;
82
83 /* Get the message size from the message header, if we didn't get the
84 * whole message in read_status then we need to re-read the
85 * message. */
86 expected_len = be32_to_cpu(hdr->length);
87 if (expected_len > count)
88 return -ENOMEM;
89
90 if (priv->len >= expected_len) {
Jason Gunthorpe8cfffc92016-02-29 12:29:47 -050091 dev_dbg(&chip->dev,
Jason Gunthorpea2871c62013-10-06 12:43:36 -060092 "%s early(buf=%*ph count=%0zx) -> ret=%d\n", __func__,
93 (int)min_t(size_t, 64, expected_len), buf, count,
94 expected_len);
95 memcpy(buf, priv->buffer, expected_len);
96 return expected_len;
97 }
98
99 rc = i2c_master_recv(client, buf, expected_len);
Jason Gunthorpe8cfffc92016-02-29 12:29:47 -0500100 dev_dbg(&chip->dev,
Jason Gunthorpea2871c62013-10-06 12:43:36 -0600101 "%s reread(buf=%*ph count=%0zx) -> ret=%d\n", __func__,
102 (int)min_t(size_t, 64, expected_len), buf, count,
103 expected_len);
104 return rc;
105}
106
107static void i2c_atmel_cancel(struct tpm_chip *chip)
108{
Jason Gunthorpe8cfffc92016-02-29 12:29:47 -0500109 dev_err(&chip->dev, "TPM operation cancellation was requested, but is not supported");
Jason Gunthorpea2871c62013-10-06 12:43:36 -0600110}
111
112static u8 i2c_atmel_read_status(struct tpm_chip *chip)
113{
Christophe Ricard9e0d39d2016-03-31 22:57:00 +0200114 struct priv_data *priv = dev_get_drvdata(&chip->dev);
Jason Gunthorpe8cfffc92016-02-29 12:29:47 -0500115 struct i2c_client *client = to_i2c_client(chip->dev.parent);
Jason Gunthorpea2871c62013-10-06 12:43:36 -0600116 int rc;
117
118 /* The TPM fails the I2C read until it is ready, so we do the entire
119 * transfer here and buffer it locally. This way the common code can
120 * properly handle the timeouts. */
121 priv->len = 0;
122 memset(priv->buffer, 0, sizeof(priv->buffer));
123
124
125 /* Once the TPM has completed the command the command remains readable
126 * until another command is issued. */
127 rc = i2c_master_recv(client, priv->buffer, sizeof(priv->buffer));
Jason Gunthorpe8cfffc92016-02-29 12:29:47 -0500128 dev_dbg(&chip->dev,
Jason Gunthorpea2871c62013-10-06 12:43:36 -0600129 "%s: sts=%d", __func__, rc);
130 if (rc <= 0)
131 return 0;
132
133 priv->len = rc;
134
135 return ATMEL_STS_OK;
136}
137
Jason Gunthorpea2871c62013-10-06 12:43:36 -0600138static bool i2c_atmel_req_canceled(struct tpm_chip *chip, u8 status)
139{
Fengguang Wuba6a09d2013-11-02 17:41:51 +0100140 return false;
Jason Gunthorpea2871c62013-10-06 12:43:36 -0600141}
142
Jason Gunthorpe01ad1fa2013-11-26 13:30:43 -0700143static const struct tpm_class_ops i2c_atmel = {
Jason Gunthorpecae8b442016-07-12 11:41:49 -0600144 .flags = TPM_OPS_AUTO_STARTUP,
Jason Gunthorpea2871c62013-10-06 12:43:36 -0600145 .status = i2c_atmel_read_status,
146 .recv = i2c_atmel_recv,
147 .send = i2c_atmel_send,
148 .cancel = i2c_atmel_cancel,
149 .req_complete_mask = ATMEL_STS_OK,
150 .req_complete_val = ATMEL_STS_OK,
151 .req_canceled = i2c_atmel_req_canceled,
Jason Gunthorpea2871c62013-10-06 12:43:36 -0600152};
153
154static int i2c_atmel_probe(struct i2c_client *client,
155 const struct i2c_device_id *id)
156{
Jason Gunthorpea2871c62013-10-06 12:43:36 -0600157 struct tpm_chip *chip;
158 struct device *dev = &client->dev;
Christophe Ricard9e0d39d2016-03-31 22:57:00 +0200159 struct priv_data *priv;
Jason Gunthorpea2871c62013-10-06 12:43:36 -0600160
161 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
162 return -ENODEV;
163
Jarkko Sakkinenafb5abc2014-12-12 11:46:34 -0800164 chip = tpmm_chip_alloc(dev, &i2c_atmel);
165 if (IS_ERR(chip))
166 return PTR_ERR(chip);
Jason Gunthorpea2871c62013-10-06 12:43:36 -0600167
Christophe Ricard9e0d39d2016-03-31 22:57:00 +0200168 priv = devm_kzalloc(dev, sizeof(struct priv_data), GFP_KERNEL);
169 if (!priv)
Jarkko Sakkinenafb5abc2014-12-12 11:46:34 -0800170 return -ENOMEM;
Jason Gunthorpea2871c62013-10-06 12:43:36 -0600171
172 /* Default timeouts */
Christophe Ricardaf782f32016-03-31 22:56:59 +0200173 chip->timeout_a = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
174 chip->timeout_b = msecs_to_jiffies(TPM_I2C_LONG_TIMEOUT);
175 chip->timeout_c = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
176 chip->timeout_d = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
Jason Gunthorpea2871c62013-10-06 12:43:36 -0600177
Christophe Ricard9e0d39d2016-03-31 22:57:00 +0200178 dev_set_drvdata(&chip->dev, priv);
179
Jason Gunthorpea2871c62013-10-06 12:43:36 -0600180 /* There is no known way to probe for this device, and all version
181 * information seems to be read via TPM commands. Thus we rely on the
182 * TPM startup process in the common code to detect the device. */
Jason Gunthorpea2871c62013-10-06 12:43:36 -0600183
Jarkko Sakkinenafb5abc2014-12-12 11:46:34 -0800184 return tpm_chip_register(chip);
Jason Gunthorpea2871c62013-10-06 12:43:36 -0600185}
186
187static int i2c_atmel_remove(struct i2c_client *client)
188{
189 struct device *dev = &(client->dev);
190 struct tpm_chip *chip = dev_get_drvdata(dev);
Jarkko Sakkinenafb5abc2014-12-12 11:46:34 -0800191 tpm_chip_unregister(chip);
Jason Gunthorpea2871c62013-10-06 12:43:36 -0600192 return 0;
193}
194
195static const struct i2c_device_id i2c_atmel_id[] = {
196 {I2C_DRIVER_NAME, 0},
197 {}
198};
199MODULE_DEVICE_TABLE(i2c, i2c_atmel_id);
200
201#ifdef CONFIG_OF
202static const struct of_device_id i2c_atmel_of_match[] = {
203 {.compatible = "atmel,at97sc3204t"},
204 {},
205};
206MODULE_DEVICE_TABLE(of, i2c_atmel_of_match);
207#endif
208
209static SIMPLE_DEV_PM_OPS(i2c_atmel_pm_ops, tpm_pm_suspend, tpm_pm_resume);
210
211static struct i2c_driver i2c_atmel_driver = {
212 .id_table = i2c_atmel_id,
213 .probe = i2c_atmel_probe,
214 .remove = i2c_atmel_remove,
215 .driver = {
216 .name = I2C_DRIVER_NAME,
Jason Gunthorpea2871c62013-10-06 12:43:36 -0600217 .pm = &i2c_atmel_pm_ops,
218 .of_match_table = of_match_ptr(i2c_atmel_of_match),
219 },
220};
221
222module_i2c_driver(i2c_atmel_driver);
223
224MODULE_AUTHOR("Jason Gunthorpe <jgunthorpe@obsidianresearch.com>");
225MODULE_DESCRIPTION("Atmel TPM I2C Driver");
226MODULE_LICENSE("GPL");