/*
 * AMD Platform Security Processor (PSP) interface
 *
 * Copyright (C) 2016-2017 Advanced Micro Devices, Inc.
 *
 * Author: Brijesh Singh <brijesh.singh@amd.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/spinlock_types.h>
#include <linux/types.h>
#include <linux/mutex.h>
#include <linux/delay.h>
#include <linux/hw_random.h>
#include <linux/ccp.h>

#include "sp-dev.h"
#include "psp-dev.h"

#define DEVICE_NAME	"sev"

static DEFINE_MUTEX(sev_cmd_mutex);
static struct sev_misc_dev *misc_dev;
static struct psp_device *psp_master;

static struct psp_device *psp_alloc_struct(struct sp_device *sp)
{
	struct device *dev = sp->dev;
	struct psp_device *psp;

	psp = devm_kzalloc(dev, sizeof(*psp), GFP_KERNEL);
	if (!psp)
		return NULL;

	psp->dev = dev;
	psp->sp = sp;

	snprintf(psp->name, sizeof(psp->name), "psp-%u", sp->ord);

	return psp;
}

static irqreturn_t psp_irq_handler(int irq, void *data)
{
	struct psp_device *psp = data;
	unsigned int status;
	int reg;

	/* Read the interrupt status: */
	status = ioread32(psp->io_regs + PSP_P2CMSG_INTSTS);

	/* Check if it is command completion: */
	if (!(status & BIT(PSP_CMD_COMPLETE_REG)))
		goto done;

	/* Check if it is SEV command completion: */
	reg = ioread32(psp->io_regs + PSP_CMDRESP);
	if (reg & PSP_CMDRESP_RESP) {
		psp->sev_int_rcvd = 1;
		wake_up(&psp->sev_int_queue);
	}

done:
	/* Clear the interrupt status by writing the same value we read. */
	iowrite32(status, psp->io_regs + PSP_P2CMSG_INTSTS);

	return IRQ_HANDLED;
}

static void sev_wait_cmd_ioc(struct psp_device *psp, unsigned int *reg)
{
	psp->sev_int_rcvd = 0;

	wait_event(psp->sev_int_queue, psp->sev_int_rcvd);
	*reg = ioread32(psp->io_regs + PSP_CMDRESP);
}

static int sev_cmd_buffer_len(int cmd)
{
	switch (cmd) {
	case SEV_CMD_INIT:			return sizeof(struct sev_data_init);
	case SEV_CMD_PLATFORM_STATUS:		return sizeof(struct sev_user_data_status);
	case SEV_CMD_PEK_CSR:			return sizeof(struct sev_data_pek_csr);
	case SEV_CMD_PEK_CERT_IMPORT:		return sizeof(struct sev_data_pek_cert_import);
	case SEV_CMD_PDH_CERT_EXPORT:		return sizeof(struct sev_data_pdh_cert_export);
	case SEV_CMD_LAUNCH_START:		return sizeof(struct sev_data_launch_start);
	case SEV_CMD_LAUNCH_UPDATE_DATA:	return sizeof(struct sev_data_launch_update_data);
	case SEV_CMD_LAUNCH_UPDATE_VMSA:	return sizeof(struct sev_data_launch_update_vmsa);
	case SEV_CMD_LAUNCH_FINISH:		return sizeof(struct sev_data_launch_finish);
	case SEV_CMD_LAUNCH_MEASURE:		return sizeof(struct sev_data_launch_measure);
	case SEV_CMD_ACTIVATE:			return sizeof(struct sev_data_activate);
	case SEV_CMD_DEACTIVATE:		return sizeof(struct sev_data_deactivate);
	case SEV_CMD_DECOMMISSION:		return sizeof(struct sev_data_decommission);
	case SEV_CMD_GUEST_STATUS:		return sizeof(struct sev_data_guest_status);
	case SEV_CMD_DBG_DECRYPT:		return sizeof(struct sev_data_dbg);
	case SEV_CMD_DBG_ENCRYPT:		return sizeof(struct sev_data_dbg);
	case SEV_CMD_SEND_START:		return sizeof(struct sev_data_send_start);
	case SEV_CMD_SEND_UPDATE_DATA:		return sizeof(struct sev_data_send_update_data);
	case SEV_CMD_SEND_UPDATE_VMSA:		return sizeof(struct sev_data_send_update_vmsa);
	case SEV_CMD_SEND_FINISH:		return sizeof(struct sev_data_send_finish);
	case SEV_CMD_RECEIVE_START:		return sizeof(struct sev_data_receive_start);
	case SEV_CMD_RECEIVE_FINISH:		return sizeof(struct sev_data_receive_finish);
	case SEV_CMD_RECEIVE_UPDATE_DATA:	return sizeof(struct sev_data_receive_update_data);
	case SEV_CMD_RECEIVE_UPDATE_VMSA:	return sizeof(struct sev_data_receive_update_vmsa);
	case SEV_CMD_LAUNCH_UPDATE_SECRET:	return sizeof(struct sev_data_launch_secret);
	default:				return 0;
	}

	return 0;
}

static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
{
	struct psp_device *psp = psp_master;
	unsigned int phys_lsb, phys_msb;
	unsigned int reg, ret = 0;

	if (!psp)
		return -ENODEV;

	/* Get the physical address of the command buffer */
	phys_lsb = data ? lower_32_bits(__psp_pa(data)) : 0;
	phys_msb = data ? upper_32_bits(__psp_pa(data)) : 0;

	dev_dbg(psp->dev, "sev command id %#x buffer 0x%08x%08x\n",
		cmd, phys_msb, phys_lsb);

	print_hex_dump_debug("(in):  ", DUMP_PREFIX_OFFSET, 16, 2, data,
			     sev_cmd_buffer_len(cmd), false);

	iowrite32(phys_lsb, psp->io_regs + PSP_CMDBUFF_ADDR_LO);
	iowrite32(phys_msb, psp->io_regs + PSP_CMDBUFF_ADDR_HI);

	reg = cmd;
	reg <<= PSP_CMDRESP_CMD_SHIFT;
	reg |= PSP_CMDRESP_IOC;
	iowrite32(reg, psp->io_regs + PSP_CMDRESP);

	/* wait for command completion */
	sev_wait_cmd_ioc(psp, &reg);

	if (psp_ret)
		*psp_ret = reg & PSP_CMDRESP_ERR_MASK;

	if (reg & PSP_CMDRESP_ERR_MASK) {
		dev_dbg(psp->dev, "sev command %#x failed (%#010x)\n",
			cmd, reg & PSP_CMDRESP_ERR_MASK);
		ret = -EIO;
	}

	print_hex_dump_debug("(out): ", DUMP_PREFIX_OFFSET, 16, 2, data,
			     sev_cmd_buffer_len(cmd), false);

	return ret;
}

static int sev_do_cmd(int cmd, void *data, int *psp_ret)
{
	int rc;

	mutex_lock(&sev_cmd_mutex);
	rc = __sev_do_cmd_locked(cmd, data, psp_ret);
	mutex_unlock(&sev_cmd_mutex);

	return rc;
}

static int __sev_platform_init_locked(int *error)
{
	struct psp_device *psp = psp_master;
	int rc = 0;

	if (!psp)
		return -ENODEV;

	if (psp->sev_state == SEV_STATE_INIT)
		return 0;

	rc = __sev_do_cmd_locked(SEV_CMD_INIT, &psp->init_cmd_buf, error);
	if (rc)
		return rc;

	psp->sev_state = SEV_STATE_INIT;
	dev_dbg(psp->dev, "SEV firmware initialized\n");

	return rc;
}

int sev_platform_init(int *error)
{
	int rc;

	mutex_lock(&sev_cmd_mutex);
	rc = __sev_platform_init_locked(error);
	mutex_unlock(&sev_cmd_mutex);

	return rc;
}
EXPORT_SYMBOL_GPL(sev_platform_init);

static int __sev_platform_shutdown_locked(int *error)
{
	int ret;

	ret = __sev_do_cmd_locked(SEV_CMD_SHUTDOWN, 0, error);
	if (ret)
		return ret;

	psp_master->sev_state = SEV_STATE_UNINIT;
	dev_dbg(psp_master->dev, "SEV firmware shutdown\n");

	return ret;
}

static int sev_platform_shutdown(int *error)
{
	int rc;

	mutex_lock(&sev_cmd_mutex);
	rc = __sev_platform_shutdown_locked(NULL);
	mutex_unlock(&sev_cmd_mutex);

	return rc;
}

static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg)
{
	return -ENOTTY;
}

static const struct file_operations sev_fops = {
	.owner	= THIS_MODULE,
	.unlocked_ioctl = sev_ioctl,
};

int sev_platform_status(struct sev_user_data_status *data, int *error)
{
	return sev_do_cmd(SEV_CMD_PLATFORM_STATUS, data, error);
}
EXPORT_SYMBOL_GPL(sev_platform_status);

int sev_guest_deactivate(struct sev_data_deactivate *data, int *error)
{
	return sev_do_cmd(SEV_CMD_DEACTIVATE, data, error);
}
EXPORT_SYMBOL_GPL(sev_guest_deactivate);

int sev_guest_activate(struct sev_data_activate *data, int *error)
{
	return sev_do_cmd(SEV_CMD_ACTIVATE, data, error);
}
EXPORT_SYMBOL_GPL(sev_guest_activate);

int sev_guest_decommission(struct sev_data_decommission *data, int *error)
{
	return sev_do_cmd(SEV_CMD_DECOMMISSION, data, error);
}
EXPORT_SYMBOL_GPL(sev_guest_decommission);

int sev_guest_df_flush(int *error)
{
	return sev_do_cmd(SEV_CMD_DF_FLUSH, 0, error);
}
EXPORT_SYMBOL_GPL(sev_guest_df_flush);

static void sev_exit(struct kref *ref)
{
	struct sev_misc_dev *misc_dev = container_of(ref, struct sev_misc_dev, refcount);

	misc_deregister(&misc_dev->misc);
}

static int sev_misc_init(struct psp_device *psp)
{
	struct device *dev = psp->dev;
	int ret;

	/*
	 * SEV feature support can be detected on multiple devices but the SEV
	 * FW commands must be issued on the master. During probe, we do not
	 * know the master hence we create /dev/sev on the first device probe.
	 * sev_do_cmd() finds the right master device to which to issue the
	 * command to the firmware.
	 */
	if (!misc_dev) {
		struct miscdevice *misc;

		misc_dev = devm_kzalloc(dev, sizeof(*misc_dev), GFP_KERNEL);
		if (!misc_dev)
			return -ENOMEM;

		misc = &misc_dev->misc;
		misc->minor = MISC_DYNAMIC_MINOR;
		misc->name = DEVICE_NAME;
		misc->fops = &sev_fops;

		ret = misc_register(misc);
		if (ret)
			return ret;

		kref_init(&misc_dev->refcount);
	} else {
		kref_get(&misc_dev->refcount);
	}

	init_waitqueue_head(&psp->sev_int_queue);
	psp->sev_misc = misc_dev;
	dev_dbg(dev, "registered SEV device\n");

	return 0;
}

static int sev_init(struct psp_device *psp)
{
	/* Check if device supports SEV feature */
	if (!(ioread32(psp->io_regs + PSP_FEATURE_REG) & 1)) {
		dev_dbg(psp->dev, "device does not support SEV\n");
		return 1;
	}

	return sev_misc_init(psp);
}

int psp_dev_init(struct sp_device *sp)
{
	struct device *dev = sp->dev;
	struct psp_device *psp;
	int ret;

	ret = -ENOMEM;
	psp = psp_alloc_struct(sp);
	if (!psp)
		goto e_err;

	sp->psp_data = psp;

	psp->vdata = (struct psp_vdata *)sp->dev_vdata->psp_vdata;
	if (!psp->vdata) {
		ret = -ENODEV;
		dev_err(dev, "missing driver data\n");
		goto e_err;
	}

	psp->io_regs = sp->io_map + psp->vdata->offset;

	/* Disable and clear interrupts until ready */
	iowrite32(0, psp->io_regs + PSP_P2CMSG_INTEN);
	iowrite32(-1, psp->io_regs + PSP_P2CMSG_INTSTS);

	/* Request an irq */
	ret = sp_request_psp_irq(psp->sp, psp_irq_handler, psp->name, psp);
	if (ret) {
		dev_err(dev, "psp: unable to allocate an IRQ\n");
		goto e_err;
	}

	ret = sev_init(psp);
	if (ret)
		goto e_irq;

	if (sp->set_psp_master_device)
		sp->set_psp_master_device(sp);

	/* Enable interrupt */
	iowrite32(-1, psp->io_regs + PSP_P2CMSG_INTEN);

	return 0;

e_irq:
	sp_free_psp_irq(psp->sp, psp);
e_err:
	sp->psp_data = NULL;

	dev_notice(dev, "psp initialization failed\n");

	return ret;
}

void psp_dev_destroy(struct sp_device *sp)
{
	struct psp_device *psp = sp->psp_data;

	if (psp->sev_misc)
		kref_put(&misc_dev->refcount, sev_exit);

	sp_free_psp_irq(sp, psp);
}

int sev_issue_cmd_external_user(struct file *filep, unsigned int cmd,
				void *data, int *error)
{
	if (!filep || filep->f_op != &sev_fops)
		return -EBADF;

	return  sev_do_cmd(cmd, data, error);
}
EXPORT_SYMBOL_GPL(sev_issue_cmd_external_user);

void psp_pci_init(void)
{
	struct sev_user_data_status *status;
	struct sp_device *sp;
	int error, rc;

	sp = sp_get_psp_master_device();
	if (!sp)
		return;

	psp_master = sp->psp_data;

	/* Initialize the platform */
	rc = sev_platform_init(&error);
	if (rc) {
		dev_err(sp->dev, "SEV: failed to INIT error %#x\n", error);
		goto err;
	}

	/* Display SEV firmware version */
	status = &psp_master->status_cmd_buf;
	rc = sev_platform_status(status, &error);
	if (rc) {
		dev_err(sp->dev, "SEV: failed to get status error %#x\n", error);
		goto err;
	}

	dev_info(sp->dev, "SEV API:%d.%d build:%d\n", status->api_major,
		 status->api_minor, status->build);
	return;

err:
	psp_master = NULL;
}

void psp_pci_exit(void)
{
	if (!psp_master)
		return;

	sev_platform_shutdown(NULL);
}