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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * ATMEL I2C TPM AT97SC3204T4 *5 * Copyright (C) 2012 V Lab Technologies6 * 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 TPM12 * devices the raw TCG formatted TPM command data is written via I2C and then13 * raw TCG formatted TPM command data is returned via I2C.14 *15 * TGC status/locality/etc functions seen in the LPC implementation do not16 * 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 131 32struct priv_data {33 size_t len;34 /* This is the amount we read on the first try. 25 was chosen to fit a35 * fair number of read responses in the buffer so a 2nd retry can be36 * avoided in small message cases. */37 u8 buffer[sizeof(struct tpm_header) + 25];38};39 40static 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 67static 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 the79 * whole message in read_status then we need to re-read the80 * 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 102static 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 107static 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 entire114 * transfer here and buffer it locally. This way the common code can115 * 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 readable121 * 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 133static bool i2c_atmel_req_canceled(struct tpm_chip *chip, u8 status)134{135 return false;136}137 138static 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 149static 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 version175 * information seems to be read via TPM commands. Thus we rely on the176 * TPM startup process in the common code to detect the device. */177 178 return tpm_chip_register(chip);179}180 181static 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 188static const struct i2c_device_id i2c_atmel_id[] = {189 { I2C_DRIVER_NAME },190 {}191};192MODULE_DEVICE_TABLE(i2c, i2c_atmel_id);193 194#ifdef CONFIG_OF195static const struct of_device_id i2c_atmel_of_match[] = {196 {.compatible = "atmel,at97sc3204t"},197 {},198};199MODULE_DEVICE_TABLE(of, i2c_atmel_of_match);200#endif201 202static SIMPLE_DEV_PM_OPS(i2c_atmel_pm_ops, tpm_pm_suspend, tpm_pm_resume);203 204static 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 215module_i2c_driver(i2c_atmel_driver);216 217MODULE_AUTHOR("Jason Gunthorpe <jgunthorpe@obsidianresearch.com>");218MODULE_DESCRIPTION("Atmel TPM I2C Driver");219MODULE_LICENSE("GPL");220