// SPDX-License-Identifier: GPL-2.0-or-later /* * ATMEL I2C TPM AT97SC3204T * * Copyright (C) 2012 V Lab Technologies * Teddy Reed * Copyright (C) 2013, Obsidian Research Corp. * Jason Gunthorpe * Device driver for ATMEL I2C TPMs. * * Teddy Reed determined the basic I2C command flow, unlike other I2C TPM * devices the raw TCG formatted TPM command data is written via I2C and then * raw TCG formatted TPM command data is returned via I2C. * * TGC status/locality/etc functions seen in the LPC implementation do not * seem to be present. */ #include #include #include #include #include #include "tpm.h" #define I2C_DRIVER_NAME "tpm_i2c_atmel" #define TPM_I2C_SHORT_TIMEOUT 750 /* ms */ #define TPM_I2C_LONG_TIMEOUT 2000 /* 2 sec */ #define ATMEL_STS_OK 1 struct priv_data { size_t len; /* This is the amount we read on the first try. 25 was chosen to fit a * fair number of read responses in the buffer so a 2nd retry can be * avoided in small message cases. */ u8 buffer[sizeof(struct tpm_header) + 25]; }; static int i2c_atmel_send(struct tpm_chip *chip, u8 *buf, size_t len) { struct priv_data *priv = dev_get_drvdata(&chip->dev); struct i2c_client *client = to_i2c_client(chip->dev.parent); s32 status; priv->len = 0; if (len <= 2) return -EIO; status = i2c_master_send(client, buf, len); dev_dbg(&chip->dev, "%s(buf=%*ph len=%0zx) -> sts=%d\n", __func__, (int)min_t(size_t, 64, len), buf, len, status); if (status < 0) return status; /* The upper layer does not support incomplete sends. */ if (status != len) return -E2BIG; return 0; } static int i2c_atmel_recv(struct tpm_chip *chip, u8 *buf, size_t count) { struct priv_data *priv = dev_get_drvdata(&chip->dev); struct i2c_client *client = to_i2c_client(chip->dev.parent); struct tpm_header *hdr = (struct tpm_header *)priv->buffer; u32 expected_len; int rc; if (priv->len == 0) return -EIO; /* Get the message size from the message header, if we didn't get the * whole message in read_status then we need to re-read the * message. */ expected_len = be32_to_cpu(hdr->length); if (expected_len > count) return -ENOMEM; if (priv->len >= expected_len) { dev_dbg(&chip->dev, "%s early(buf=%*ph count=%0zx) -> ret=%d\n", __func__, (int)min_t(size_t, 64, expected_len), buf, count, expected_len); memcpy(buf, priv->buffer, expected_len); return expected_len; } rc = i2c_master_recv(client, buf, expected_len); dev_dbg(&chip->dev, "%s reread(buf=%*ph count=%0zx) -> ret=%d\n", __func__, (int)min_t(size_t, 64, expected_len), buf, count, expected_len); return rc; } static void i2c_atmel_cancel(struct tpm_chip *chip) { dev_err(&chip->dev, "TPM operation cancellation was requested, but is not supported"); } static u8 i2c_atmel_read_status(struct tpm_chip *chip) { struct priv_data *priv = dev_get_drvdata(&chip->dev); struct i2c_client *client = to_i2c_client(chip->dev.parent); int rc; /* The TPM fails the I2C read until it is ready, so we do the entire * transfer here and buffer it locally. This way the common code can * properly handle the timeouts. */ priv->len = 0; memset(priv->buffer, 0, sizeof(priv->buffer)); /* Once the TPM has completed the command the command remains readable * until another command is issued. */ rc = i2c_master_recv(client, priv->buffer, sizeof(priv->buffer)); dev_dbg(&chip->dev, "%s: sts=%d", __func__, rc); if (rc <= 0) return 0; priv->len = rc; return ATMEL_STS_OK; } static bool i2c_atmel_req_canceled(struct tpm_chip *chip, u8 status) { return false; } static const struct tpm_class_ops i2c_atmel = { .flags = TPM_OPS_AUTO_STARTUP, .status = i2c_atmel_read_status, .recv = i2c_atmel_recv, .send = i2c_atmel_send, .cancel = i2c_atmel_cancel, .req_complete_mask = ATMEL_STS_OK, .req_complete_val = ATMEL_STS_OK, .req_canceled = i2c_atmel_req_canceled, }; static int i2c_atmel_probe(struct i2c_client *client) { struct tpm_chip *chip; struct device *dev = &client->dev; struct priv_data *priv; if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) return -ENODEV; chip = tpmm_chip_alloc(dev, &i2c_atmel); if (IS_ERR(chip)) return PTR_ERR(chip); priv = devm_kzalloc(dev, sizeof(struct priv_data), GFP_KERNEL); if (!priv) return -ENOMEM; /* Default timeouts */ chip->timeout_a = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT); chip->timeout_b = msecs_to_jiffies(TPM_I2C_LONG_TIMEOUT); chip->timeout_c = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT); chip->timeout_d = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT); dev_set_drvdata(&chip->dev, priv); /* There is no known way to probe for this device, and all version * information seems to be read via TPM commands. Thus we rely on the * TPM startup process in the common code to detect the device. */ return tpm_chip_register(chip); } static void i2c_atmel_remove(struct i2c_client *client) { struct device *dev = &(client->dev); struct tpm_chip *chip = dev_get_drvdata(dev); tpm_chip_unregister(chip); } static const struct i2c_device_id i2c_atmel_id[] = { { I2C_DRIVER_NAME }, {} }; MODULE_DEVICE_TABLE(i2c, i2c_atmel_id); #ifdef CONFIG_OF static const struct of_device_id i2c_atmel_of_match[] = { {.compatible = "atmel,at97sc3204t"}, {}, }; MODULE_DEVICE_TABLE(of, i2c_atmel_of_match); #endif static SIMPLE_DEV_PM_OPS(i2c_atmel_pm_ops, tpm_pm_suspend, tpm_pm_resume); static struct i2c_driver i2c_atmel_driver = { .id_table = i2c_atmel_id, .probe = i2c_atmel_probe, .remove = i2c_atmel_remove, .driver = { .name = I2C_DRIVER_NAME, .pm = &i2c_atmel_pm_ops, .of_match_table = of_match_ptr(i2c_atmel_of_match), }, }; module_i2c_driver(i2c_atmel_driver); MODULE_AUTHOR("Jason Gunthorpe "); MODULE_DESCRIPTION("Atmel TPM I2C Driver"); MODULE_LICENSE("GPL");