1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * ATMEL I2C TPM AT97SC3204T 4 * 5 * Copyright (C) 2012 V Lab Technologies 6 * Teddy Reed <teddy@prosauce.org> 7 * Copyright (C) 2013, Obsidian Research Corp. 8 * Jason Gunthorpe <jgunthorpe@obsidianresearch.com> 9 * Device driver for ATMEL I2C TPMs. 10 * 11 * Teddy Reed determined the basic I2C command flow, unlike other I2C TPM 12 * devices the raw TCG formatted TPM command data is written via I2C and then 13 * raw TCG formatted TPM command data is returned via I2C. 14 * 15 * TGC status/locality/etc functions seen in the LPC implementation do not 16 * seem to be present. 17 */ 18 #include <linux/init.h> 19 #include <linux/module.h> 20 #include <linux/moduleparam.h> 21 #include <linux/slab.h> 22 #include <linux/i2c.h> 23 #include "tpm.h" 24 25 #define I2C_DRIVER_NAME "tpm_i2c_atmel" 26 27 #define TPM_I2C_SHORT_TIMEOUT 750 /* ms */ 28 #define TPM_I2C_LONG_TIMEOUT 2000 /* 2 sec */ 29 30 #define ATMEL_STS_OK 1 31 32 struct priv_data { 33 size_t len; 34 /* This is the amount we read on the first try. 25 was chosen to fit a 35 * fair number of read responses in the buffer so a 2nd retry can be 36 * avoided in small message cases. */ 37 u8 buffer[sizeof(struct tpm_header) + 25]; 38 }; 39 40 static int i2c_atmel_send(struct tpm_chip *chip, u8 *buf, size_t bufsiz, 41 size_t len) 42 { 43 struct priv_data *priv = dev_get_drvdata(&chip->dev); 44 struct i2c_client *client = to_i2c_client(chip->dev.parent); 45 s32 status; 46 47 priv->len = 0; 48 49 if (len <= 2) 50 return -EIO; 51 52 status = i2c_master_send(client, buf, len); 53 54 dev_dbg(&chip->dev, 55 "%s(buf=%*ph len=%0zx) -> sts=%d\n", __func__, 56 (int)min_t(size_t, 64, len), buf, len, status); 57 58 if (status < 0) 59 return status; 60 61 /* The upper layer does not support incomplete sends. */ 62 if (status != len) 63 return -E2BIG; 64 65 return 0; 66 } 67 68 static int i2c_atmel_recv(struct tpm_chip *chip, u8 *buf, size_t count) 69 { 70 struct priv_data *priv = dev_get_drvdata(&chip->dev); 71 struct i2c_client *client = to_i2c_client(chip->dev.parent); 72 struct tpm_header *hdr = (struct tpm_header *)priv->buffer; 73 u32 expected_len; 74 int rc; 75 76 if (priv->len == 0) 77 return -EIO; 78 79 /* Get the message size from the message header, if we didn't get the 80 * whole message in read_status then we need to re-read the 81 * message. */ 82 expected_len = be32_to_cpu(hdr->length); 83 if (expected_len > count) 84 return -ENOMEM; 85 86 if (priv->len >= expected_len) { 87 dev_dbg(&chip->dev, 88 "%s early(buf=%*ph count=%0zx) -> ret=%d\n", __func__, 89 (int)min_t(size_t, 64, expected_len), buf, count, 90 expected_len); 91 memcpy(buf, priv->buffer, expected_len); 92 return expected_len; 93 } 94 95 rc = i2c_master_recv(client, buf, expected_len); 96 dev_dbg(&chip->dev, 97 "%s reread(buf=%*ph count=%0zx) -> ret=%d\n", __func__, 98 (int)min_t(size_t, 64, expected_len), buf, count, 99 expected_len); 100 return rc; 101 } 102 103 static void i2c_atmel_cancel(struct tpm_chip *chip) 104 { 105 dev_err(&chip->dev, "TPM operation cancellation was requested, but is not supported"); 106 } 107 108 static u8 i2c_atmel_read_status(struct tpm_chip *chip) 109 { 110 struct priv_data *priv = dev_get_drvdata(&chip->dev); 111 struct i2c_client *client = to_i2c_client(chip->dev.parent); 112 int rc; 113 114 /* The TPM fails the I2C read until it is ready, so we do the entire 115 * transfer here and buffer it locally. This way the common code can 116 * properly handle the timeouts. */ 117 priv->len = 0; 118 memset(priv->buffer, 0, sizeof(priv->buffer)); 119 120 121 /* Once the TPM has completed the command the command remains readable 122 * until another command is issued. */ 123 rc = i2c_master_recv(client, priv->buffer, sizeof(priv->buffer)); 124 dev_dbg(&chip->dev, 125 "%s: sts=%d", __func__, rc); 126 if (rc <= 0) 127 return 0; 128 129 priv->len = rc; 130 131 return ATMEL_STS_OK; 132 } 133 134 static bool i2c_atmel_req_canceled(struct tpm_chip *chip, u8 status) 135 { 136 return false; 137 } 138 139 static const struct tpm_class_ops i2c_atmel = { 140 .flags = TPM_OPS_AUTO_STARTUP, 141 .status = i2c_atmel_read_status, 142 .recv = i2c_atmel_recv, 143 .send = i2c_atmel_send, 144 .cancel = i2c_atmel_cancel, 145 .req_complete_mask = ATMEL_STS_OK, 146 .req_complete_val = ATMEL_STS_OK, 147 .req_canceled = i2c_atmel_req_canceled, 148 }; 149 150 static int i2c_atmel_probe(struct i2c_client *client) 151 { 152 struct tpm_chip *chip; 153 struct device *dev = &client->dev; 154 struct priv_data *priv; 155 156 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 157 return -ENODEV; 158 159 chip = tpmm_chip_alloc(dev, &i2c_atmel); 160 if (IS_ERR(chip)) 161 return PTR_ERR(chip); 162 163 priv = devm_kzalloc(dev, sizeof(struct priv_data), GFP_KERNEL); 164 if (!priv) 165 return -ENOMEM; 166 167 /* Default timeouts */ 168 chip->timeout_a = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT); 169 chip->timeout_b = msecs_to_jiffies(TPM_I2C_LONG_TIMEOUT); 170 chip->timeout_c = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT); 171 chip->timeout_d = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT); 172 173 dev_set_drvdata(&chip->dev, priv); 174 175 /* There is no known way to probe for this device, and all version 176 * information seems to be read via TPM commands. Thus we rely on the 177 * TPM startup process in the common code to detect the device. */ 178 179 return tpm_chip_register(chip); 180 } 181 182 static void i2c_atmel_remove(struct i2c_client *client) 183 { 184 struct device *dev = &(client->dev); 185 struct tpm_chip *chip = dev_get_drvdata(dev); 186 tpm_chip_unregister(chip); 187 } 188 189 static const struct i2c_device_id i2c_atmel_id[] = { 190 { I2C_DRIVER_NAME }, 191 {} 192 }; 193 MODULE_DEVICE_TABLE(i2c, i2c_atmel_id); 194 195 #ifdef CONFIG_OF 196 static const struct of_device_id i2c_atmel_of_match[] = { 197 {.compatible = "atmel,at97sc3204t"}, 198 {}, 199 }; 200 MODULE_DEVICE_TABLE(of, i2c_atmel_of_match); 201 #endif 202 203 static SIMPLE_DEV_PM_OPS(i2c_atmel_pm_ops, tpm_pm_suspend, tpm_pm_resume); 204 205 static struct i2c_driver i2c_atmel_driver = { 206 .id_table = i2c_atmel_id, 207 .probe = i2c_atmel_probe, 208 .remove = i2c_atmel_remove, 209 .driver = { 210 .name = I2C_DRIVER_NAME, 211 .pm = &i2c_atmel_pm_ops, 212 .of_match_table = of_match_ptr(i2c_atmel_of_match), 213 }, 214 }; 215 216 module_i2c_driver(i2c_atmel_driver); 217 218 MODULE_AUTHOR("Jason Gunthorpe <jgunthorpe@obsidianresearch.com>"); 219 MODULE_DESCRIPTION("Atmel TPM I2C Driver"); 220 MODULE_LICENSE("GPL"); 221