path: root/drivers/char/tpm/tpm_i2c_nuvoton.c

// SPDX-License-Identifier: GPL-2.0-or-later
 /******************************************************************************
 * Nuvoton TPM I2C Device Driver Interface for WPCT301/NPCT501/NPCT6XX,
 * based on the TCG TPM Interface Spec version 1.2.
 * Specifications at www.trustedcomputinggroup.org
 *
 * Copyright (C) 2011, Nuvoton Technology Corporation.
 *  Dan Morav <dan.morav@nuvoton.com>
 * Copyright (C) 2013, Obsidian Research Corp.
 *  Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
 *
 * Nuvoton contact information: APC.Support@nuvoton.com
 *****************************************************************************/

#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/wait.h>
#include <linux/i2c.h>
#include <linux/of_device.h>
#include "tpm.h"

/* I2C interface offsets */
#define TPM_STS			0x00
#define TPM_BURST_COUNT		0x01
#define TPM_DATA_FIFO_W		0x20
#define TPM_DATA_FIFO_R		0x40
#define TPM_VID_DID_RID		0x60
#define TPM_I2C_RETRIES		5
/*
 * I2C bus device maximum buffer size w/o counting I2C address or command
 * i.e. max size required for I2C write is 34 = addr, command, 32 bytes data
 */
#define TPM_I2C_MAX_BUF_SIZE           32
#define TPM_I2C_RETRY_COUNT            32
#define TPM_I2C_BUS_DELAY              1000      	/* usec */
#define TPM_I2C_RETRY_DELAY_SHORT      (2 * 1000)	/* usec */
#define TPM_I2C_RETRY_DELAY_LONG       (10 * 1000) 	/* usec */
#define TPM_I2C_DELAY_RANGE            300		/* usec */

#define OF_IS_TPM2 ((void *)1)
#define I2C_IS_TPM2 1

struct priv_data {
	int irq;
	unsigned int intrs;
	wait_queue_head_t read_queue;
};

static s32 i2c_nuvoton_read_buf(struct i2c_client *client, u8 offset, u8 size,
				u8 *data)
{
	s32 status;

	status = i2c_smbus_read_i2c_block_data(client, offset, size, data);
	dev_dbg(&client->dev,
		"%s(offset=%u size=%u data=%*ph) -> sts=%d\n", __func__,
		offset, size, (int)size, data, status);
	return status;
}

static s32 i2c_nuvoton_write_buf(struct i2c_client *client, u8 offset, u8 size,
				 u8 *data)
{
	s32 status;

	status = i2c_smbus_write_i2c_block_data(client, offset, size, data);
	dev_dbg(&client->dev,
		"%s(offset=%u size=%u data=%*ph) -> sts=%d\n", __func__,
		offset, size, (int)size, data, status);
	return status;
}

#define TPM_STS_VALID          0x80
#define TPM_STS_COMMAND_READY  0x40
#define TPM_STS_GO             0x20
#define TPM_STS_DATA_AVAIL     0x10
#define TPM_STS_EXPECT         0x08
#define TPM_STS_RESPONSE_RETRY 0x02
#define TPM_STS_ERR_VAL        0x07    /* bit2...bit0 reads always 0 */

#define TPM_I2C_SHORT_TIMEOUT  750     /* ms */
#define TPM_I2C_LONG_TIMEOUT   2000    /* 2 sec */

/* read TPM_STS register */
static u8 i2c_nuvoton_read_status(struct tpm_chip *chip)
{
	struct i2c_client *client = to_i2c_client(chip->dev.parent);
	s32 status;
	u8 data;

	status = i2c_nuvoton_read_buf(client, TPM_STS, 1, &data);
	if (status <= 0) {
		dev_err(&chip->dev, "%s() error return %d\n", __func__,
			status);
		data = TPM_STS_ERR_VAL;
	}

	return data;
}

/* write byte to TPM_STS register */
static s32 i2c_nuvoton_write_status(struct i2c_client *client, u8 data)
{
	s32 status;
	int i;

	/* this causes the current command to be aborted */
	for (i = 0, status = -1; i < TPM_I2C_RETRY_COUNT && status < 0; i++) {
		status = i2c_nuvoton_write_buf(client, TPM_STS, 1, &data);
		if (status < 0)
			usleep_range(TPM_I2C_BUS_DELAY, TPM_I2C_BUS_DELAY
				     + TPM_I2C_DELAY_RANGE);
	}
	return status;
}

/* write commandReady to TPM_STS register */
static void i2c_nuvoton_ready(struct tpm_chip *chip)
{
	struct i2c_client *client = to_i2c_client(chip->dev.parent);
	s32 status;

	/* this causes the current command to be aborted */
	status = i2c_nuvoton_write_status(client, TPM_STS_COMMAND_READY);
	if (status < 0)
		dev_err(&chip->dev,
			"%s() fail to write TPM_STS.commandReady\n", __func__);
}

/* read burstCount field from TPM_STS register
 * return -1 on fail to read */
static int i2c_nuvoton_get_burstcount(struct i2c_client *client,
				      struct tpm_chip *chip)
{
	unsigned long stop = jiffies + chip->timeout_d;
	s32 status;
	int burst_count = -1;
	u8 data;

	/* wait for burstcount to be non-zero */
	do {
		/* in I2C burstCount is 1 byte */
		status = i2c_nuvoton_read_buf(client, TPM_BURST_COUNT, 1,
					      &data);
		if (status > 0 && data > 0) {
			burst_count = min_t(u8, TPM_I2C_MAX_BUF_SIZE, data);
			break;
		}
		usleep_range(TPM_I2C_BUS_DELAY, TPM_I2C_BUS_DELAY
			     + TPM_I2C_DELAY_RANGE);
	} while (time_before(jiffies, stop));

	return burst_count;
}

/*
 * WPCT301/NPCT501/NPCT6XX SINT# supports only dataAvail
 * any call to this function which is not waiting for dataAvail will
 * set queue to NULL to avoid waiting for interrupt
 */
static bool i2c_nuvoton_check_status(struct tpm_chip *chip, u8 mask, u8 value)
{
	u8 status = i2c_nuvoton_read_status(chip);
	return (status != TPM_STS_ERR_VAL) && ((status & mask) == value);
}

static int i2c_nuvoton_wait_for_stat(struct tpm_chip *chip, u8 mask, u8 value,
				     u32 timeout, wait_queue_head_t *queue)
{
	if ((chip->flags & TPM_CHIP_FLAG_IRQ) && queue) {
		s32 rc;
		struct priv_data *priv = dev_get_drvdata(&chip->dev);
		unsigned int cur_intrs = priv->intrs;

		enable_irq(priv->irq);
		rc = wait_event_interruptible_timeout(*queue,
						      cur_intrs != priv->intrs,
						      timeout);
		if (rc > 0)
			return 0;
		/* At this point we know that the SINT pin is asserted, so we
		 * do not need to do i2c_nuvoton_check_status */
	} else {
		unsigned long ten_msec, stop;
		bool status_valid;

		/* check current status */
		status_valid = i2c_nuvoton_check_status(chip, mask, value);
		if (status_valid)
			return 0;

		/* use polling to wait for the event */
		ten_msec = jiffies + usecs_to_jiffies(TPM_I2C_RETRY_DELAY_LONG);
		stop = jiffies + timeout;
		do {
			if (time_before(jiffies, ten_msec))
				usleep_range(TPM_I2C_RETRY_DELAY_SHORT,
					     TPM_I2C_RETRY_DELAY_SHORT
					     + TPM_I2C_DELAY_RANGE);
			else
				usleep_range(TPM_I2C_RETRY_DELAY_LONG,
					     TPM_I2C_RETRY_DELAY_LONG
					     + TPM_I2C_DELAY_RANGE);
			status_valid = i2c_nuvoton_check_status(chip, mask,
								value);
			if (status_valid)
				return 0;
		} while (time_before(jiffies, stop));
	}
	dev_err(&chip->dev, "%s(%02x, %02x) -> timeout\n", __func__, mask,
		value);
	return -ETIMEDOUT;
}

/* wait for dataAvail field to be set in the TPM_STS register */
static int i2c_nuvoton_wait_for_data_avail(struct tpm_chip *chip, u32 timeout,
					   wait_queue_head_t *queue)
{
	return