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

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2014 Intel Corporation
 *
 * Authors:
 * Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
 *
 * Maintained by: <tpmdd-devel@lists.sourceforge.net>
 *
 * This device driver implements the TPM interface as defined in
 * the TCG CRB 2.0 TPM specification.
 */

#include <linux/acpi.h>
#include <linux/highmem.h>
#include <linux/rculist.h>
#include <linux/module.h>
#include <linux/pm_runtime.h>
#ifdef CONFIG_ARM64
#include <linux/arm-smccc.h>
#endif
#include "tpm_crb_ffa.h"
#include "tpm.h"

#define ACPI_SIG_TPM2 "TPM2"
#define TPM_CRB_MAX_RESOURCES 3

static const guid_t crb_acpi_start_guid =
	GUID_INIT(0x6BBF6CAB, 0x5463, 0x4714,
		  0xB7, 0xCD, 0xF0, 0x20, 0x3C, 0x03, 0x68, 0xD4);

enum crb_defaults {
	CRB_ACPI_START_REVISION_ID = 1,
	CRB_ACPI_START_INDEX = 1,
};

enum crb_loc_ctrl {
	CRB_LOC_CTRL_REQUEST_ACCESS	= BIT(0),
	CRB_LOC_CTRL_RELINQUISH		= BIT(1),
};

enum crb_loc_state {
	CRB_LOC_STATE_LOC_ASSIGNED	= BIT(1),
	CRB_LOC_STATE_TPM_REG_VALID_STS	= BIT(7),
};

enum crb_ctrl_req {
	CRB_CTRL_REQ_CMD_READY	= BIT(0),
	CRB_CTRL_REQ_GO_IDLE	= BIT(1),
};

enum crb_ctrl_sts {
	CRB_CTRL_STS_ERROR	= BIT(0),
	CRB_CTRL_STS_TPM_IDLE	= BIT(1),
};

enum crb_start {
	CRB_START_INVOKE	= BIT(0),
};

enum crb_cancel {
	CRB_CANCEL_INVOKE	= BIT(0),
};

struct crb_regs_head {
	u32 loc_state;
	u32 reserved1;
	u32 loc_ctrl;
	u32 loc_sts;
	u8 reserved2[32];
	u64 intf_id;
	u64 ctrl_ext;
} __packed;

struct crb_regs_tail {
	u32 ctrl_req;
	u32 ctrl_sts;
	u32 ctrl_cancel;
	u32 ctrl_start;
	u32 ctrl_int_enable;
	u32 ctrl_int_sts;
	u32 ctrl_cmd_size;
	u32 ctrl_cmd_pa_low;
	u32 ctrl_cmd_pa_high;
	u32 ctrl_rsp_size;
	u64 ctrl_rsp_pa;
} __packed;

enum crb_status {
	CRB_DRV_STS_COMPLETE	= BIT(0),
};

struct crb_priv {
	u32 sm;
	const char *hid;
	struct crb_regs_head __iomem *regs_h;
	struct crb_regs_tail __iomem *regs_t;
	u8 __iomem *cmd;
	u8 __iomem *rsp;
	u32 cmd_size;
	u32 smc_func_id;
	u32 __iomem *pluton_start_addr;
	u32 __iomem *pluton_reply_addr;
	u8 ffa_flags;
	u8 ffa_attributes;
};

struct tpm2_crb_smc {
	u32 interrupt;
	u8 interrupt_flags;
	u8 op_flags;
	u16 reserved2;
	u32 smc_func_id;
};

/* CRB over FFA start method parameters in TCG2 ACPI table */
struct tpm2_crb_ffa {
	u8 flags;
	u8 attributes;
	u16 partition_id;
	u8 reserved[8];
};

struct tpm2_crb_pluton {
	u64 start_addr;
	u64 reply_addr;
};

/*
 * Returns true if the start method supports idle.
 */
static inline bool tpm_crb_has_idle(u32 start_method)
{
	return !(start_method == ACPI_TPM2_START_METHOD ||
	       start_method == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD ||
	       start_method == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC);
}

static bool crb_wait_for_reg_32(u32 __iomem *reg, u32 mask, u32 value,
				unsigned long timeout)
{
	ktime_t start;
	ktime_t stop;

	start = ktime_get();
	stop = ktime_add(start, ms_to_ktime(timeout));

	do {
		if ((ioread32(reg) & mask) == value)
			return true;

		usleep_range(50, 100);
	} while (ktime_before(ktime_get(), stop));

	return ((ioread32(reg) & mask) == value);
}

static int crb_try_pluton_doorbell(struct crb_priv *priv, bool wait_for_complete)
{
	if (priv->sm != ACPI_TPM2_COMMAND_BUFFER_WITH_PLUTON)
		return 0;

	if (!crb_wait_for_reg_32(priv->pluton_reply_addr, ~0, 1, TPM2_TIMEOUT_C))
		return -ETIME;

	iowrite32(1, priv->pluton_start_addr);
	if (wait_for_complete == false)
		return 0;

	if (!crb_wait_for_reg_32(priv->pluton_start_addr,
				 0xffffffff, 0, 200))
		return -ETIME;

	return 0;
}

/**
 * __crb_go_idle - request tpm crb device to go the idle state
 *
 * @dev:  crb device
 * @priv: crb private data
 * @loc:  locality
 *
 * Write CRB_CTRL_REQ_GO_IDLE to TPM_CRB_CTRL_REQ
 * The device should respond within TIMEOUT_C by clearing the bit.
 * Anyhow, we do not wait here as a consequent CMD_READY request
 * will be handled correctly even if idle was not completed.
 *
 * The function does nothing for devices with ACPI-start method
 * or SMC-start method.
 *
 * Return: 0 always
 */
static int __crb_go_idle(struct device *dev, struct crb_priv *priv, int loc)
{
	int rc;

	if (!tpm_crb_has_idle(priv->sm))