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 len) 41 { 42 struct priv_data *priv = dev_get_drvdata(&chip->dev); 43 struct i2c_client *client = to_i2c_client(chip->dev.parent); 44 s32 status; 45 46 priv->len = 0; 47 48 if (len <= 2) 49 return -EIO; 50 51 status = i2c_master_send(client, buf, len); 52 53 dev_dbg(&chip->dev, 54 "%s(buf=%*ph len=%0zx) -> sts=%d\n", __func__, 55 (int)min_t(size_t, 64, len), buf, len, status); 56 57 if (status < 0) 58 return status; 59 60 /* The upper layer does not support incomplete sends. */ 61 if (status != len) 62 return -E2BIG; 63 64 return 0; 65 } 66 67 static int i2c_atmel_recv(struct tpm_chip *chip, u8 *buf, size_t count) 68 { 69 struct priv_data *priv = dev_get_drvdata(&chip->dev); 70 struct i2c_client *client = to_i2c_client(chip->dev.parent); 71 struct tpm_header *hdr = (struct tpm_header *)priv->buffer; 72 u32 expected_len; 73 int rc; 74 75 if (priv->len == 0) 76 return -EIO; 77 78 /* Get the message size from the message header, if we didn't get the 79 * whole message in read_status then we need to re-read the 80 * message. */ 81 expected_len = be32_to_cpu(hdr->length); 82 if (expected_len > count) 83 return -ENOMEM; 84 85 if (priv->len >= expected_len) { 86 dev_dbg(&chip->dev, 87 "%s early(buf=%*ph count=%0zx) -> ret=%d\n", __func__, 88 (int)min_t(size_t, 64, expected_len), buf, count, 89 expected_len); 90 memcpy(buf, priv->buffer, expected_len); 91 return expected_len; 92 } 93 94 rc = i2c_master_recv(client, buf, expected_len); 95 dev_dbg(&chip->dev, 96 "%s reread(buf=%*ph count=%0zx) -> ret=%d\n", __func__, 97 (int)min_t(size_t, 64, expected_len), buf, count, 98 expected_len); 99 return rc; 100 } 101 102 static void i2c_atmel_cancel(struct tpm_chip *chip) 103 { 104 dev_err(&chip->dev, "TPM operation cancellation was requested, but is not supported"); 105 } 106 107 static u8 i2c_atmel_read_status(struct tpm_chip *chip) 108 { 109 struct priv_data *priv = dev_get_drvdata(&chip->dev); 110 struct i2c_client *client = to_i2c_client(chip->dev.parent); 111 int rc; 112 113 /* The TPM fails the I2C read until it is ready, so we do the entire 114 * transfer here and buffer it locally. This way the common code can 115 * properly handle the timeouts. */ 116 priv->len = 0; 117 memset(priv->buffer, 0, sizeof(priv->buffer)); 118 119 120 /* Once the TPM has completed the command the command remains readable 121 * until another command is issued. */ 122 rc = i2c_master_recv(client, priv->buffer, sizeof(priv->buffer)); 123 dev_dbg(&chip->dev, 124 "%s: sts=%d", __func__, rc); 125 if (rc <= 0) 126 return 0; 127 128 priv->len = rc; 129 130 return ATMEL_STS_OK; 131 } 132 133 static bool i2c_atmel_req_canceled(struct tpm_chip *chip, u8 status) 134 { 135 return false; 136 } 137 138 static const struct tpm_class_ops i2c_atmel = { 139 .flags = TPM_OPS_AUTO_STARTUP, 140 .status = i2c_atmel_read_status, 141 .recv = i2c_atmel_recv, 142 .send = i2c_atmel_send, 143 .cancel = i2c_atmel_cancel, 144 .req_complete_mask = ATMEL_STS_OK, 145 .req_complete_val = ATMEL_STS_OK, 146 .req_canceled = i2c_atmel_req_canceled, 147 }; 148 149 static int i2c_atmel_probe(struct i2c_client *client) 150 { 151 struct tpm_chip *chip; 152 struct device *dev = &client->dev; 153 struct priv_data *priv; 154 155 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 156 return -ENODEV; 157 158 chip = tpmm_chip_alloc(dev, &i2c_atmel); 159 if (IS_ERR(chip)) 160 return PTR_ERR(chip); 161 162 priv = devm_kzalloc(dev, sizeof(struct priv_data), GFP_KERNEL); 163 if (!priv) 164 return -ENOMEM; 165 166 /* Default timeouts */ 167 chip->timeout_a = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT); 168 chip->timeout_b = msecs_to_jiffies(TPM_I2C_LONG_TIMEOUT); 169 chip->timeout_c = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT); 170 chip->timeout_d = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT); 171 172 dev_set_drvdata(&chip->dev, priv); 173 174 /* There is no known way to probe for this device, and all version 175 * information seems to be read via TPM commands. Thus we rely on the 176 * TPM startup process in the common code to detect the device. */ 177 178 return tpm_chip_register(chip); 179 } 180 181 static void i2c_atmel_remove(struct i2c_client *client) 182 { 183 struct device *dev = &(client->dev); 184 struct tpm_chip *chip = dev_get_drvdata(dev); 185 tpm_chip_unregister(chip); 186 } 187 188 static const struct i2c_device_id i2c_atmel_id[] = { 189 {I2C_DRIVER_NAME, 0}, 190 {} 191 }; 192 MODULE_DEVICE_TABLE(i2c, i2c_atmel_id); 193 194 #ifdef CONFIG_OF 195 static const struct of_device_id i2c_atmel_of_match[] = { 196 {.compatible = "atmel,at97sc3204t"}, 197 {}, 198 }; 199 MODULE_DEVICE_TABLE(of, i2c_atmel_of_match); 200 #endif 201 202 static SIMPLE_DEV_PM_OPS(i2c_atmel_pm_ops, tpm_pm_suspend, tpm_pm_resume); 203 204 static struct i2c_driver i2c_atmel_driver = { 205 .id_table = i2c_atmel_id, 206 .probe = i2c_atmel_probe, 207 .remove = i2c_atmel_remove, 208 .driver = { 209 .name = I2C_DRIVER_NAME, 210 .pm = &i2c_atmel_pm_ops, 211 .of_match_table = of_match_ptr(i2c_atmel_of_match), 212 }, 213 }; 214 215 module_i2c_driver(i2c_atmel_driver); 216 217 MODULE_AUTHOR("Jason Gunthorpe <jgunthorpe@obsidianresearch.com>"); 218 MODULE_DESCRIPTION("Atmel TPM I2C Driver"); 219 MODULE_LICENSE("GPL"); 220