+/*
+ * 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.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see http://www.gnu.org/licenses/>.
+ */
+#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_output_header) + 25];
+};
+
+static int i2c_atmel_send(struct tpm_chip *chip, u8 *buf, size_t len)
+{
+ struct priv_data *priv = chip->vendor.priv;
+ struct i2c_client *client = to_i2c_client(chip->dev);
+ 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);
+ return status;
+}
+
+static int i2c_atmel_recv(struct tpm_chip *chip, u8 *buf, size_t count)
+{
+ struct priv_data *priv = chip->vendor.priv;
+ struct i2c_client *client = to_i2c_client(chip->dev);
+ struct tpm_output_header *hdr =
+ (struct tpm_output_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 = chip->vendor.priv;
+ struct i2c_client *client = to_i2c_client(chip->dev);
+ 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 const struct file_operations i2c_atmel_ops = {
+ .owner = THIS_MODULE,
+ .llseek = no_llseek,
+ .open = tpm_open,
+ .read = tpm_read,
+ .write = tpm_write,
+ .release = tpm_release,
+};
+
+static DEVICE_ATTR(pubek, S_IRUGO, tpm_show_pubek, NULL);
+static DEVICE_ATTR(pcrs, S_IRUGO, tpm_show_pcrs, NULL);
+static DEVICE_ATTR(enabled, S_IRUGO, tpm_show_enabled, NULL);
+static DEVICE_ATTR(active, S_IRUGO, tpm_show_active, NULL);
+static DEVICE_ATTR(owned, S_IRUGO, tpm_show_owned, NULL);
+static DEVICE_ATTR(temp_deactivated, S_IRUGO, tpm_show_temp_deactivated, NULL);
+static DEVICE_ATTR(caps, S_IRUGO, tpm_show_caps, NULL);
+static DEVICE_ATTR(cancel, S_IWUSR | S_IWGRP, NULL, tpm_store_cancel);
+static DEVICE_ATTR(durations, S_IRUGO, tpm_show_durations, NULL);
+static DEVICE_ATTR(timeouts, S_IRUGO, tpm_show_timeouts, NULL);
+
+static struct attribute *i2c_atmel_attrs[] = {
+ &dev_attr_pubek.attr,
+ &dev_attr_pcrs.attr,
+ &dev_attr_enabled.attr,
+ &dev_attr_active.attr,
+ &dev_attr_owned.attr,
+ &dev_attr_temp_deactivated.attr,
+ &dev_attr_caps.attr,
+ &dev_attr_cancel.attr,
+ &dev_attr_durations.attr,
+ &dev_attr_timeouts.attr,
+ NULL,
+};
+
+static struct attribute_group i2c_atmel_attr_grp = {
+ .attrs = i2c_atmel_attrs
+};
+
+static bool i2c_atmel_req_canceled(struct tpm_chip *chip, u8 status)
+{
+ return 0;
+}
+
+static const struct tpm_vendor_specific i2c_atmel = {
+ .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,
+ .attr_group = &i2c_atmel_attr_grp,
+ .miscdev.fops = &i2c_atmel_ops,
+};
+
+static int i2c_atmel_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ int rc;
+ struct tpm_chip *chip;
+ struct device *dev = &client->dev;
+
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+ return -ENODEV;
+
+ chip = tpm_register_hardware(dev, &i2c_atmel);
+ if (!chip) {
+ dev_err(dev, "%s() error in tpm_register_hardware\n", __func__);
+ return -ENODEV;
+ }
+
+ chip->vendor.priv = devm_kzalloc(dev, sizeof(struct priv_data),
+ GFP_KERNEL);
+
+ /* Default timeouts */
+ chip->vendor.timeout_a = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
+ chip->vendor.timeout_b = msecs_to_jiffies(TPM_I2C_LONG_TIMEOUT);
+ chip->vendor.timeout_c = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
+ chip->vendor.timeout_d = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
+ chip->vendor.irq = 0;
+
+ /* 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. */
+ if (tpm_get_timeouts(chip)) {
+ rc = -ENODEV;
+ goto out_err;
+ }
+
+ if (tpm_do_selftest(chip)) {
+ rc = -ENODEV;
+ goto out_err;
+ }
+
+ return 0;
+
+out_err:
+ tpm_dev_vendor_release(chip);
+ tpm_remove_hardware(chip->dev);
+ return rc;
+}
+
+static int i2c_atmel_remove(struct i2c_client *client)
+{
+ struct device *dev = &(client->dev);
+ struct tpm_chip *chip = dev_get_drvdata(dev);
+
+ if (chip)
+ tpm_dev_vendor_release(chip);
+ tpm_remove_hardware(dev);
+ kfree(chip);
+ return 0;
+}
+
+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,
+ .owner = THIS_MODULE,
+ .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");
projects / cascardo / linux.git / commitdiff