// SPDX-License-Identifier: GPL-2.0
/*
 * Driver for Xilinx TMR Inject IP.
 *
 * Copyright (C) 2022 Advanced Micro Devices, Inc.
 *
 * Description:
 * This driver is developed for TMR Inject IP,The Triple Modular Redundancy(TMR)
 * Inject provides fault injection.
 */

#include <asm/xilinx_mb_manager.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/fault-inject.h>

/* TMR Inject Register offsets */
#define XTMR_INJECT_CR_OFFSET		0x0
#define XTMR_INJECT_AIR_OFFSET		0x4
#define XTMR_INJECT_IIR_OFFSET		0xC
#define XTMR_INJECT_EAIR_OFFSET		0x10
#define XTMR_INJECT_ERR_OFFSET		0x204

/* Register Bitmasks/shifts */
#define XTMR_INJECT_CR_CPUID_SHIFT	8
#define XTMR_INJECT_CR_IE_SHIFT		10
#define XTMR_INJECT_IIR_ADDR_MASK	GENMASK(31, 16)

#define XTMR_INJECT_MAGIC_MAX_VAL	255

/**
 * struct xtmr_inject_dev - Driver data for TMR Inject
 * @regs: device physical base address
 * @magic: Magic hardware configuration value
 */
struct xtmr_inject_dev {
	void __iomem *regs;
	u32 magic;
};

static DECLARE_FAULT_ATTR(inject_fault);
static char *inject_request;
module_param(inject_request, charp, 0);
MODULE_PARM_DESC(inject_request, "default fault injection attributes");
static struct dentry *dbgfs_root;

/* IO accessors */
static inline void xtmr_inject_write(struct xtmr_inject_dev *xtmr_inject,
				     u32 addr, u32 value)
{
	iowrite32(value, xtmr_inject->regs + addr);
}

static inline u32 xtmr_inject_read(struct xtmr_inject_dev *xtmr_inject,
				   u32 addr)
{
	return ioread32(xtmr_inject->regs + addr);
}

static int xtmr_inject_set(void *data, u64 val)
{
	if (val != 1)
		return -EINVAL;

	xmb_inject_err();
	return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(xtmr_inject_fops, NULL, xtmr_inject_set, "%llu\n");

static void xtmr_init_debugfs(struct xtmr_inject_dev *xtmr_inject)
{
	struct dentry *dir;

	dbgfs_root = debugfs_create_dir("xtmr_inject", NULL);
	dir = fault_create_debugfs_attr("inject_fault", dbgfs_root,
					&inject_fault);
	debugfs_create_file("inject_fault", 0200, dir, NULL,
			    &xtmr_inject_fops);
}

static void xtmr_inject_init(struct xtmr_inject_dev *xtmr_inject)
{
	u32 cr_val;

	if (inject_request)
		setup_fault_attr(&inject_fault, inject_request);
	/* Allow fault injection */
	cr_val = xtmr_inject->magic |
		 (1 << XTMR_INJECT_CR_IE_SHIFT) |
		 (1 << XTMR_INJECT_CR_CPUID_SHIFT);
	xtmr_inject_write(xtmr_inject, XTMR_INJECT_CR_OFFSET,
			  cr_val);
	/* Initialize the address inject and instruction inject registers */
	xtmr_inject_write(xtmr_inject, XTMR_INJECT_AIR_OFFSET,
			  XMB_INJECT_ERR_OFFSET);
	xtmr_inject_write(xtmr_inject, XTMR_INJECT_IIR_OFFSET,
			  XMB_INJECT_ERR_OFFSET & XTMR_INJECT_IIR_ADDR_MASK);
}

/**
 * xtmr_inject_probe - Driver probe function
 * @pdev: Pointer to the platform_device structure
 *
 * This is the driver probe routine. It does all the memory
 * allocation for the device.
 *
 * Return: 0 on success and failure value on error
 */
static int xtmr_inject_probe(struct platform_device *pdev)
{
	struct xtmr_inject_dev *xtmr_inject;
	int err;

	xtmr_inject = devm_kzalloc(&pdev->dev, sizeof(*xtmr_inject),
				   GFP_KERNEL);
	if (!xtmr_inject)
		return -ENOMEM;

	xtmr_inject->regs = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(xtmr_inject->regs))
		return PTR_ERR(xtmr_inject->regs);

	err = of_property_read_u32(pdev->dev.of_node, "xlnx,magic",
				   &xtmr_inject->magic);
	if (err < 0) {
		dev_err(&pdev->dev, "unable to read xlnx,magic property");
		return err;
	}

	if (xtmr_inject->magic > XTMR_INJECT_MAGIC_MAX_VAL) {
		dev_err(&pdev->dev, "invalid xlnx,magic property value");
		return -EINVAL;
	}

	/* Initialize TMR Inject */
	xtmr_inject_init(xtmr_inject);

	xtmr_init_debugfs(xtmr_inject);

	platform_set_drvdata(pdev, xtmr_inject);

	return 0;
}

static int xtmr_inject_remove(struct platform_device *pdev)
{
	debugfs_remove_recursive(dbgfs_root);
	dbgfs_root = NULL;
	return 0;
}

static const struct of_device_id xtmr_inject_of_match[] = {
	{
		.compatible = "xlnx,tmr-inject-1.0",
	},
	{ /* end of table */ }
};
MODULE_DEVICE_TABLE(of, xtmr_inject_of_match);

static struct platform_driver xtmr_inject_driver = {
	.driver = {
		.name = "xilinx-tmr_inject",
		.of_match_table = xtmr_inject_of_match,
	},
	.probe = xtmr_inject_probe,
	.remove = xtmr_inject_remove,
};
module_platform_driver(xtmr_inject_driver);
MODULE_AUTHOR("Advanced Micro Devices, Inc");
MODULE_DESCRIPTION("Xilinx TMR Inject Driver");
MODULE_LICENSE("GPL");