Jason Gunthorpe | a2871c6 | 2013-10-06 12:43:36 -0600 | [diff] [blame] | 1 | /* |
| 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 | |
| 44 | struct 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 | |
| 52 | static int i2c_atmel_send(struct tpm_chip *chip, u8 *buf, size_t len) |
| 53 | { |
| 54 | struct priv_data *priv = chip->vendor.priv; |
| 55 | struct i2c_client *client = to_i2c_client(chip->dev); |
| 56 | 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 | |
| 65 | dev_dbg(chip->dev, |
| 66 | "%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 | |
| 71 | static int i2c_atmel_recv(struct tpm_chip *chip, u8 *buf, size_t count) |
| 72 | { |
| 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; |
| 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) { |
| 91 | dev_dbg(chip->dev, |
| 92 | "%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); |
| 100 | dev_dbg(chip->dev, |
| 101 | "%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 | |
| 107 | static void i2c_atmel_cancel(struct tpm_chip *chip) |
| 108 | { |
| 109 | dev_err(chip->dev, "TPM operation cancellation was requested, but is not supported"); |
| 110 | } |
| 111 | |
| 112 | static u8 i2c_atmel_read_status(struct tpm_chip *chip) |
| 113 | { |
| 114 | struct priv_data *priv = chip->vendor.priv; |
| 115 | struct i2c_client *client = to_i2c_client(chip->dev); |
| 116 | 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)); |
| 128 | dev_dbg(chip->dev, |
| 129 | "%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 | |
| 138 | static const struct file_operations i2c_atmel_ops = { |
| 139 | .owner = THIS_MODULE, |
| 140 | .llseek = no_llseek, |
| 141 | .open = tpm_open, |
| 142 | .read = tpm_read, |
| 143 | .write = tpm_write, |
| 144 | .release = tpm_release, |
| 145 | }; |
| 146 | |
| 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); |
| 157 | |
| 158 | static struct attribute *i2c_atmel_attrs[] = { |
| 159 | &dev_attr_pubek.attr, |
| 160 | &dev_attr_pcrs.attr, |
| 161 | &dev_attr_enabled.attr, |
| 162 | &dev_attr_active.attr, |
| 163 | &dev_attr_owned.attr, |
| 164 | &dev_attr_temp_deactivated.attr, |
| 165 | &dev_attr_caps.attr, |
| 166 | &dev_attr_cancel.attr, |
| 167 | &dev_attr_durations.attr, |
| 168 | &dev_attr_timeouts.attr, |
| 169 | NULL, |
| 170 | }; |
| 171 | |
| 172 | static struct attribute_group i2c_atmel_attr_grp = { |
| 173 | .attrs = i2c_atmel_attrs |
| 174 | }; |
| 175 | |
| 176 | static bool i2c_atmel_req_canceled(struct tpm_chip *chip, u8 status) |
| 177 | { |
| 178 | return 0; |
| 179 | } |
| 180 | |
| 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, |
| 191 | }; |
| 192 | |
| 193 | static int i2c_atmel_probe(struct i2c_client *client, |
| 194 | const struct i2c_device_id *id) |
| 195 | { |
| 196 | int rc; |
| 197 | struct tpm_chip *chip; |
| 198 | struct device *dev = &client->dev; |
| 199 | |
| 200 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) |
| 201 | return -ENODEV; |
| 202 | |
| 203 | chip = tpm_register_hardware(dev, &i2c_atmel); |
| 204 | if (!chip) { |
| 205 | dev_err(dev, "%s() error in tpm_register_hardware\n", __func__); |
| 206 | return -ENODEV; |
| 207 | } |
| 208 | |
| 209 | chip->vendor.priv = devm_kzalloc(dev, sizeof(struct priv_data), |
| 210 | GFP_KERNEL); |
| 211 | |
| 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; |
| 218 | |
| 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)) { |
| 223 | rc = -ENODEV; |
| 224 | goto out_err; |
| 225 | } |
| 226 | |
| 227 | if (tpm_do_selftest(chip)) { |
| 228 | rc = -ENODEV; |
| 229 | goto out_err; |
| 230 | } |
| 231 | |
| 232 | return 0; |
| 233 | |
| 234 | out_err: |
| 235 | tpm_dev_vendor_release(chip); |
| 236 | tpm_remove_hardware(chip->dev); |
| 237 | return rc; |
| 238 | } |
| 239 | |
| 240 | static int i2c_atmel_remove(struct i2c_client *client) |
| 241 | { |
| 242 | struct device *dev = &(client->dev); |
| 243 | struct tpm_chip *chip = dev_get_drvdata(dev); |
| 244 | |
| 245 | if (chip) |
| 246 | tpm_dev_vendor_release(chip); |
| 247 | tpm_remove_hardware(dev); |
| 248 | kfree(chip); |
| 249 | return 0; |
| 250 | } |
| 251 | |
| 252 | static const struct i2c_device_id i2c_atmel_id[] = { |
| 253 | {I2C_DRIVER_NAME, 0}, |
| 254 | {} |
| 255 | }; |
| 256 | MODULE_DEVICE_TABLE(i2c, i2c_atmel_id); |
| 257 | |
| 258 | #ifdef CONFIG_OF |
| 259 | static const struct of_device_id i2c_atmel_of_match[] = { |
| 260 | {.compatible = "atmel,at97sc3204t"}, |
| 261 | {}, |
| 262 | }; |
| 263 | MODULE_DEVICE_TABLE(of, i2c_atmel_of_match); |
| 264 | #endif |
| 265 | |
| 266 | static SIMPLE_DEV_PM_OPS(i2c_atmel_pm_ops, tpm_pm_suspend, tpm_pm_resume); |
| 267 | |
| 268 | static struct i2c_driver i2c_atmel_driver = { |
| 269 | .id_table = i2c_atmel_id, |
| 270 | .probe = i2c_atmel_probe, |
| 271 | .remove = i2c_atmel_remove, |
| 272 | .driver = { |
| 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), |
| 277 | }, |
| 278 | }; |
| 279 | |
| 280 | module_i2c_driver(i2c_atmel_driver); |
| 281 | |
| 282 | MODULE_AUTHOR("Jason Gunthorpe <jgunthorpe@obsidianresearch.com>"); |
| 283 | MODULE_DESCRIPTION("Atmel TPM I2C Driver"); |
| 284 | MODULE_LICENSE("GPL"); |