diff options
Diffstat (limited to 'drivers/char/tpm/tpm_i2c_atmel.c')
| -rw-r--r-- | drivers/char/tpm/tpm_i2c_atmel.c | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/drivers/char/tpm/tpm_i2c_atmel.c b/drivers/char/tpm/tpm_i2c_atmel.c new file mode 100644 index 000000000..4be3677c1 --- /dev/null +++ b/drivers/char/tpm/tpm_i2c_atmel.c @@ -0,0 +1,220 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * ATMEL I2C TPM AT97SC3204T + * + * Copyright (C) 2012 V Lab Technologies + * Teddy Reed <teddy@prosauce.org> + * Copyright (C) 2013, Obsidian Research Corp. + * Jason Gunthorpe <jgunthorpe@obsidianresearch.com> + * 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 <linux/init.h> +#include <linux/module.h> +#include <linux/moduleparam.h> +#include <linux/slab.h> +#include <linux/i2c.h> +#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, + const struct i2c_device_id *id) +{ + 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, 0}, + {} +}; +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 <jgunthorpe@obsidianresearch.com>"); +MODULE_DESCRIPTION("Atmel TPM I2C Driver"); +MODULE_LICENSE("GPL"); |