2 * ATMEL I2C TPM AT97SC3204T
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.
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.
14 * TGC status/locality/etc functions seen in the LPC implementation do not
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.
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.
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/>.
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>
37 #define I2C_DRIVER_NAME "tpm_i2c_atmel"
39 #define TPM_I2C_SHORT_TIMEOUT 750 /* ms */
40 #define TPM_I2C_LONG_TIMEOUT 2000 /* 2 sec */
42 #define ATMEL_STS_OK 1
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];
52 static int i2c_atmel_send(struct tpm_chip *chip, u8 *buf, size_t len)
54 struct priv_data *priv = chip->vendor.priv;
55 struct i2c_client *client = to_i2c_client(chip->dev);
63 status = i2c_master_send(client, buf, len);
66 "%s(buf=%*ph len=%0zx) -> sts=%d\n", __func__,
67 (int)min_t(size_t, 64, len), buf, len, status);
71 static int i2c_atmel_recv(struct tpm_chip *chip, u8 *buf, size_t count)
73 struct priv_data *priv = chip->vendor.priv;
74 struct i2c_client *client = to_i2c_client(chip->dev);
75 struct tpm_output_header *hdr =
76 (struct tpm_output_header *)priv->buffer;
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
86 expected_len = be32_to_cpu(hdr->length);
87 if (expected_len > count)
90 if (priv->len >= expected_len) {
92 "%s early(buf=%*ph count=%0zx) -> ret=%d\n", __func__,
93 (int)min_t(size_t, 64, expected_len), buf, count,
95 memcpy(buf, priv->buffer, expected_len);
99 rc = i2c_master_recv(client, buf, expected_len);
101 "%s reread(buf=%*ph count=%0zx) -> ret=%d\n", __func__,
102 (int)min_t(size_t, 64, expected_len), buf, count,
107 static void i2c_atmel_cancel(struct tpm_chip *chip)
109 dev_err(chip->dev, "TPM operation cancellation was requested, but is not supported");
112 static u8 i2c_atmel_read_status(struct tpm_chip *chip)
114 struct priv_data *priv = chip->vendor.priv;
115 struct i2c_client *client = to_i2c_client(chip->dev);
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. */
122 memset(priv->buffer, 0, sizeof(priv->buffer));
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));
129 "%s: sts=%d", __func__, rc);
138 static const struct file_operations i2c_atmel_ops = {
139 .owner = THIS_MODULE,
144 .release = tpm_release,
147 static DEVICE_ATTR(pubek, S_IRUGO, tpm_show_pubek, NULL);
148 static DEVICE_ATTR(pcrs, S_IRUGO, tpm_show_pcrs, NULL);
149 static DEVICE_ATTR(enabled, S_IRUGO, tpm_show_enabled, NULL);
150 static DEVICE_ATTR(active, S_IRUGO, tpm_show_active, NULL);
151 static DEVICE_ATTR(owned, S_IRUGO, tpm_show_owned, NULL);
152 static DEVICE_ATTR(temp_deactivated, S_IRUGO, tpm_show_temp_deactivated, NULL);
153 static DEVICE_ATTR(caps, S_IRUGO, tpm_show_caps, NULL);
154 static DEVICE_ATTR(cancel, S_IWUSR | S_IWGRP, NULL, tpm_store_cancel);
155 static DEVICE_ATTR(durations, S_IRUGO, tpm_show_durations, NULL);
156 static DEVICE_ATTR(timeouts, S_IRUGO, tpm_show_timeouts, NULL);
158 static struct attribute *i2c_atmel_attrs[] = {
159 &dev_attr_pubek.attr,
161 &dev_attr_enabled.attr,
162 &dev_attr_active.attr,
163 &dev_attr_owned.attr,
164 &dev_attr_temp_deactivated.attr,
166 &dev_attr_cancel.attr,
167 &dev_attr_durations.attr,
168 &dev_attr_timeouts.attr,
172 static struct attribute_group i2c_atmel_attr_grp = {
173 .attrs = i2c_atmel_attrs
176 static bool i2c_atmel_req_canceled(struct tpm_chip *chip, u8 status)
181 static const struct tpm_vendor_specific i2c_atmel = {
182 .status = i2c_atmel_read_status,
183 .recv = i2c_atmel_recv,
184 .send = i2c_atmel_send,
185 .cancel = i2c_atmel_cancel,
186 .req_complete_mask = ATMEL_STS_OK,
187 .req_complete_val = ATMEL_STS_OK,
188 .req_canceled = i2c_atmel_req_canceled,
189 .attr_group = &i2c_atmel_attr_grp,
190 .miscdev.fops = &i2c_atmel_ops,
193 static int i2c_atmel_probe(struct i2c_client *client,
194 const struct i2c_device_id *id)
197 struct tpm_chip *chip;
198 struct device *dev = &client->dev;
200 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
203 chip = tpm_register_hardware(dev, &i2c_atmel);
205 dev_err(dev, "%s() error in tpm_register_hardware\n", __func__);
209 chip->vendor.priv = devm_kzalloc(dev, sizeof(struct priv_data),
212 /* Default timeouts */
213 chip->vendor.timeout_a = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
214 chip->vendor.timeout_b = msecs_to_jiffies(TPM_I2C_LONG_TIMEOUT);
215 chip->vendor.timeout_c = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
216 chip->vendor.timeout_d = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
217 chip->vendor.irq = 0;
219 /* There is no known way to probe for this device, and all version
220 * information seems to be read via TPM commands. Thus we rely on the
221 * TPM startup process in the common code to detect the device. */
222 if (tpm_get_timeouts(chip)) {
227 if (tpm_do_selftest(chip)) {
235 tpm_dev_vendor_release(chip);
236 tpm_remove_hardware(chip->dev);
240 static int i2c_atmel_remove(struct i2c_client *client)
242 struct device *dev = &(client->dev);
243 struct tpm_chip *chip = dev_get_drvdata(dev);
246 tpm_dev_vendor_release(chip);
247 tpm_remove_hardware(dev);
252 static const struct i2c_device_id i2c_atmel_id[] = {
253 {I2C_DRIVER_NAME, 0},
256 MODULE_DEVICE_TABLE(i2c, i2c_atmel_id);
259 static const struct of_device_id i2c_atmel_of_match[] = {
260 {.compatible = "atmel,at97sc3204t"},
263 MODULE_DEVICE_TABLE(of, i2c_atmel_of_match);
266 static SIMPLE_DEV_PM_OPS(i2c_atmel_pm_ops, tpm_pm_suspend, tpm_pm_resume);
268 static struct i2c_driver i2c_atmel_driver = {
269 .id_table = i2c_atmel_id,
270 .probe = i2c_atmel_probe,
271 .remove = i2c_atmel_remove,
273 .name = I2C_DRIVER_NAME,
274 .owner = THIS_MODULE,
275 .pm = &i2c_atmel_pm_ops,
276 .of_match_table = of_match_ptr(i2c_atmel_of_match),
280 module_i2c_driver(i2c_atmel_driver);
282 MODULE_AUTHOR("Jason Gunthorpe <jgunthorpe@obsidianresearch.com>");
283 MODULE_DESCRIPTION("Atmel TPM I2C Driver");
284 MODULE_LICENSE("GPL");