/*
 * APEI Error INJection support
 *
 * EINJ provides a hardware error injection mechanism, this is useful
 * for debugging and testing of other APEI and RAS features.
 *
 * For more information about EINJ, please refer to ACPI Specification
 * version 4.0, section 17.5.
 *
 * Copyright 2009-2010 Intel Corp.
 *   Author: Huang Ying <ying.huang@intel.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.
 *
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/nmi.h>
#include <linux/delay.h>
#include <acpi/acpi.h>

#include "apei-internal.h"

#define EINJ_PFX "EINJ: "

#define SPIN_UNIT		100			/* 100ns */
/* Firmware should respond within 1 milliseconds */
#define FIRMWARE_TIMEOUT	(1 * NSEC_PER_MSEC)

/*
 * Some BIOSes allow parameters to the SET_ERROR_TYPE entries in the
 * EINJ table through an unpublished extension. Use with caution as
 * most will ignore the parameter and make their own choice of address
 * for error injection.  This extension is used only if
 * param_extension module parameter is specified.
 */
struct einj_parameter {
	u64 type;
	u64 reserved1;
	u64 reserved2;
	u64 param1;
	u64 param2;
};

#define EINJ_OP_BUSY			0x1
#define EINJ_STATUS_SUCCESS		0x0
#define EINJ_STATUS_FAIL		0x1
#define EINJ_STATUS_INVAL		0x2

#define EINJ_TAB_ENTRY(tab)						\
	((struct acpi_whea_header *)((char *)(tab) +			\
				    sizeof(struct acpi_table_einj)))

static bool param_extension;
module_param(param_extension, bool, 0);

static struct acpi_table_einj *einj_tab;

static struct apei_resources einj_resources;

static struct apei_exec_ins_type einj_ins_type[] = {
	[ACPI_EINJ_READ_REGISTER] = {
		.flags = APEI_EXEC_INS_ACCESS_REGISTER,
		.run   = apei_exec_read_register,
	},
	[ACPI_EINJ_READ_REGISTER_VALUE] = {
		.flags = APEI_EXEC_INS_ACCESS_REGISTER,
		.run   = apei_exec_read_register_value,
	},
	[ACPI_EINJ_WRITE_REGISTER] = {
		.flags = APEI_EXEC_INS_ACCESS_REGISTER,
		.run   = apei_exec_write_register,
	},
	[ACPI_EINJ_WRITE_REGISTER_VALUE] = {
		.flags = APEI_EXEC_INS_ACCESS_REGISTER,
		.run   = apei_exec_write_register_value,
	},
	[ACPI_EINJ_NOOP] = {
		.flags = 0,
		.run   = apei_exec_noop,
	},
};

/*
 * Prevent EINJ interpreter to run simultaneously, because the
 * corresponding firmware implementation may not work properly when
 * invoked simultaneously.
 */
static DEFINE_MUTEX(einj_mutex);

static struct einj_parameter *einj_param;

#ifndef writeq
static inline void writeq(__u64 val, volatile void __iomem *addr)
{
	writel(val, addr);
	writel(val >> 32, addr+4);
}
#endif

static void einj_exec_ctx_init(struct apei_exec_context *ctx)
{
	apei_exec_ctx_init(ctx, einj_ins_type, ARRAY_SIZE(einj_ins_type),
			   EINJ_TAB_ENTRY(einj_tab), einj_tab->entries);
}

static int __einj_get_available_error_type(u32 *type)
{
	struct apei_exec_context ctx;
	int rc;

	einj_exec_ctx_init(&ctx);
	rc = apei_exec_run(&ctx, ACPI_EINJ_GET_ERROR_TYPE);
	if (rc)
		return rc;
	*type = apei_exec_ctx_get_output(&ctx);

	return 0;
}

/* Get error injection capabilities of the platform */
static int einj_get_available_error_type(u32 *type)
{
	int rc;

	mutex_lock(&einj_mutex);
	rc = __einj_get_available_error_type(type);
	mutex_unlock(&einj_mutex);

	return rc;
}

static int einj_timedout(u64 *t)
{
	if ((s64)*t < SPIN_UNIT) {
		pr_warning(FW_WARN EINJ_PFX
			   "Firmware does not respond in time\n");
		return 1;
	}
	*t -= SPIN_UNIT;
	ndelay(SPIN_UNIT);
	touch_nmi_watchdog();
	return 0;
}

static u64 einj_get_parameter_address(void)
{
	int i;
	u64 paddr = 0;
	struct acpi_whea_header *entry;

	entry = EINJ_TAB_ENTRY(einj_tab);
	for (i = 0; i < einj_tab->entries; i++) {
		if (entry->action == ACPI_EINJ_SET_ERROR_TYPE &&
		    entry->instruction == ACPI_EINJ_WRITE_REGISTER &&
		    entry->register_region.space_id ==
		    ACPI_ADR_SPACE_SYSTEM_MEMORY)
			memcpy(&paddr, &entry->register_region.address,
			       sizeof(paddr));
		entry++;
	}

	return paddr;
}

/* do sanity check to trigger table */
static int einj_check_trigger_header(struct acpi_einj_trigger *trigger_tab)
{
	if (trigger_tab->header_size != sizeof(struct acpi_einj_trigger))
		return -EINVAL;
	if (trigger_tab->table_size > PAGE_SIZE ||
	    trigger_tab->table_size <= trigger_tab->header_size)
		return -EINVAL;
	if (trigger_tab->entry_count !=
	    (trigger_tab->table_size - trigger_tab->header_size) /
	    sizeof(struct acpi_einj_entry))
		return -EINVAL;

	return 0;
}

/* Execute instructions in trigger error action table */
static int __einj_error_trigger(u64 trigger_paddr)
{
	struct acpi_einj_trigger *trigger_tab = NULL;
	struct apei_exec_context trigger_ctx;
	struct apei_resources trigger_resources;
	struct acpi_whea_header *trigger_entry;
	struct resource *r;
	u32 table_size;
	int rc = -EIO;

	r = request_mem_region(trigger_paddr, sizeof(*trigger_tab),
			       "APEI EINJ Trigger Table");
	if (!r) {
		pr_err(EINJ_PFX
	"Can not request iomem region <%016llx-%016llx> for Trigger table.\n",
		       (unsigned long long)trigger_paddr,
		       (unsigned long long)trigger_paddr+sizeof(*trigger_tab));
		goto out;
	}
	trigger_tab = ioremap_cache(trigger_paddr, sizeof(*trigger_tab));
	if (!trigger_tab) {
		pr_err(EINJ_PFX "Failed to map trigger table!\n");
		goto out_rel_header;
	}
	rc = einj_check_trigger_header(trigger_tab);
	if (rc) {
		pr_warning(FW_BUG EINJ_PFX
			   "The trigger error action table is invalid\n");
		goto out_rel_header;
	}
	rc = -EIO;
	table_size = trigger_tab->table_size;
	r = request_mem_region(trigger_paddr + sizeof(*trigger_tab),
			       table_size - sizeof(*trigger_tab),
			       "APEI EINJ Trigger Table");
	if (!r) {
		pr_err(EINJ_PFX
"Can not request iomem region <%016llx-%016llx> for Trigger Table Entry.\n",
		       (unsigned long long)trigger_paddr+sizeof(*trigger_tab),
		       (unsigned long long)trigger_paddr + table_size);
		goto out_rel_header;
	}
	iounmap(trigger_tab);
	trigger_tab = ioremap_cache(trigger_paddr, table_size);
	if (!trigger_tab) {
		pr_err(EINJ_PFX "Failed to map trigger table!\n");
		goto out_rel_entry;
	}
	trigger_entry = (struct acpi_whea_header *)
		((char *)trigger_tab + sizeof(struct acpi_einj_trigger));
	apei_resources_init(&trigger_resources);
	apei_exec_ctx_init(&trigger_ctx, einj_ins_type,
			   ARRAY_SIZE(einj_ins_type),
			   trigger_entry, trigger_tab->entry_count);
	rc = apei_exec_collect_resources(&trigger_ctx, &trigger_resources);
	if (rc)
		goto out_fini;
	rc = apei_resources_sub(&trigger_resources, &einj_resources);
	if (rc)
		goto out_fini;
	rc = apei_resources_request(&trigger_resources, "APEI EINJ Trigger");
	if (rc)
		goto out_fini;
	rc = apei_exec_pre_map_gars(&trigger_ctx);
	if (rc)
		goto out_release;

	rc = apei_exec_run(&trigger_ctx, ACPI_EINJ_TRIGGER_ERROR);

	apei_exec_post_unmap_gars(&trigger_ctx);
out_release:
	apei_resources_release(&trigger_resources);
out_fini:
	apei_resources_fini(&trigger_resources);
out_rel_entry:
	release_mem_region(trigger_paddr + sizeof(*trigger_tab),
			   table_size - sizeof(*trigger_tab));
out_rel_header:
	release_mem_region(trigger_paddr, sizeof(*trigger_tab));
out:
	if (trigger_tab)
		iounmap(trigger_tab);

	return rc;
}

static int __einj_error_inject(u32 type, u64 param1, u64 param2)
{
	struct apei_exec_context ctx;
	u64 val, trigger_paddr, timeout = FIRMWARE_TIMEOUT;
	int rc;

	einj_exec_ctx_init(&ctx);

	rc = apei_exec_run_optional(&ctx, ACPI_EINJ_BEGIN_OPERATION);
	if (rc)
		return rc;
	apei_exec_ctx_set_input(&ctx, type);
	rc = apei_exec_run(&ctx, ACPI_EINJ_SET_ERROR_TYPE);
	if (rc)
		return rc;
	if (einj_param) {
		writeq(param1, &einj_param->param1);
		writeq(param2, &einj_param->param2);
	}
	rc = apei_exec_run(&ctx, ACPI_EINJ_EXECUTE_OPERATION);
	if (rc)
		return rc;
	for (;;) {
		rc = apei_exec_run(&ctx, ACPI_EINJ_CHECK_BUSY_STATUS);
		if (rc)
			return rc;
		val = apei_exec_ctx_get_output(&ctx);
		if (!(val & EINJ_OP_BUSY))
			break;
		if (einj_timedout(&timeout))
			return -EIO;
	}
	rc = apei_exec_run(&ctx, ACPI_EINJ_GET_COMMAND_STATUS);
	if (rc)
		return rc;
	val = apei_exec_ctx_get_output(&ctx);
	if (val != EINJ_STATUS_SUCCESS)
		return -EBUSY;

	rc = apei_exec_run(&ctx, ACPI_EINJ_GET_TRIGGER_TABLE);
	if (rc)
		return rc;
	trigger_paddr = apei_exec_ctx_get_output(&ctx);
	rc = __einj_error_trigger(trigger_paddr);
	if (rc)
		return rc;
	rc = apei_exec_run_optional(&ctx, ACPI_EINJ_END_OPERATION);

	return rc;
}

/* Inject the specified hardware error */
static int einj_error_inject(u32 type, u64 param1, u64 param2)
{
	int rc;

	mutex_lock(&einj_mutex);
	rc = __einj_error_inject(type, param1, param2);
	mutex_unlock(&einj_mutex);

	return rc;
}

static u32 error_type;
static u64 error_param1;
static u64 error_param2;
static struct dentry *einj_debug_dir;

static int available_error_type_show(struct seq_file *m, void *v)
{
	int rc;
	u32 available_error_type = 0;

	rc = einj_get_available_error_type(&available_error_type);
	if (rc)
		return rc;
	if (available_error_type & 0x0001)
		seq_printf(m, "0x00000001\tProcessor Correctable\n");
	if (available_error_type & 0x0002)
		seq_printf(m, "0x00000002\tProcessor Uncorrectable non-fatal\n");
	if (available_error_type & 0x0004)
		seq_printf(m, "0x00000004\tProcessor Uncorrectable fatal\n");
	if (available_error_type & 0x0008)
		seq_printf(m, "0x00000008\tMemory Correctable\n");
	if (available_error_type & 0x0010)
		seq_printf(m, "0x00000010\tMemory Uncorrectable non-fatal\n");
	if (available_error_type & 0x0020)
		seq_printf(m, "0x00000020\tMemory Uncorrectable fatal\n");
	if (available_error_type & 0x0040)
		seq_printf(m, "0x00000040\tPCI Express Correctable\n");
	if (available_error_type & 0x0080)
		seq_printf(m, "0x00000080\tPCI Express Uncorrectable non-fatal\n");
	if (available_error_type & 0x0100)
		seq_printf(m, "0x00000100\tPCI Express Uncorrectable fatal\n");
	if (available_error_type & 0x0200)
		seq_printf(m, "0x00000200\tPlatform Correctable\n");
	if (available_error_type & 0x0400)
		seq_printf(m, "0x00000400\tPlatform Uncorrectable non-fatal\n");
	if (available_error_type & 0x0800)
		seq_printf(m, "0x00000800\tPlatform Uncorrectable fatal\n");

	return 0;
}

static int available_error_type_open(struct inode *inode, struct file *file)
{
	return single_open(file, available_error_type_show, NULL);
}

static const struct file_operations available_error_type_fops = {
	.open		= available_error_type_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};

static int error_type_get(void *data, u64 *val)
{
	*val = error_type;

	return 0;
}

static int error_type_set(void *data, u64 val)
{
	int rc;
	u32 available_error_type = 0;

	/* Only one error type can be specified */
	if (val & (val - 1))
		return -EINVAL;
	rc = einj_get_available_error_type(&available_error_type);
	if (rc)
		return rc;
	if (!(val & available_error_type))
		return -EINVAL;
	error_type = val;

	return 0;
}

DEFINE_SIMPLE_ATTRIBUTE(error_type_fops, error_type_get,
			error_type_set, "0x%llx\n");

static int error_inject_set(void *data, u64 val)
{
	if (!error_type)
		return -EINVAL;

	return einj_error_inject(error_type, error_param1, error_param2);
}

DEFINE_SIMPLE_ATTRIBUTE(error_inject_fops, NULL,
			error_inject_set, "%llu\n");

static int einj_check_table(struct acpi_table_einj *einj_tab)
{
	if ((einj_tab->header_length !=
	     (sizeof(struct acpi_table_einj) - sizeof(einj_tab->header)))
	    && (einj_tab->header_length != sizeof(struct acpi_table_einj)))
		return -EINVAL;
	if (einj_tab->header.length < sizeof(struct acpi_table_einj))
		return -EINVAL;
	if (einj_tab->entries !=
	    (einj_tab->header.length - sizeof(struct acpi_table_einj)) /
	    sizeof(struct acpi_einj_entry))
		return -EINVAL;

	return 0;
}

static int __init einj_init(void)
{
	int rc;
	u64 param_paddr;
	acpi_status status;
	struct dentry *fentry;
	struct apei_exec_context ctx;

	if (acpi_disabled)
		return -ENODEV;

	status = acpi_get_table(ACPI_SIG_EINJ, 0,
				(struct acpi_table_header **)&einj_tab);
	if (status == AE_NOT_FOUND) {
		pr_info(EINJ_PFX "Table is not found!\n");
		return -ENODEV;
	} else if (ACPI_FAILURE(status)) {
		const char *msg = acpi_format_exception(status);
		pr_err(EINJ_PFX "Failed to get table, %s\n", msg);
		return -EINVAL;
	}

	rc = einj_check_table(einj_tab);
	if (rc) {
		pr_warning(FW_BUG EINJ_PFX "EINJ table is invalid\n");
		return -EINVAL;
	}

	rc = -ENOMEM;
	einj_debug_dir = debugfs_create_dir("einj", apei_get_debugfs_dir());
	if (!einj_debug_dir)
		goto err_cleanup;
	fentry = debugfs_create_file("available_error_type", S_IRUSR,
				     einj_debug_dir, NULL,
				     &available_error_type_fops);
	if (!fentry)
		goto err_cleanup;
	fentry = debugfs_create_file("error_type", S_IRUSR | S_IWUSR,
				     einj_debug_dir, NULL, &error_type_fops);
	if (!fentry)
		goto err_cleanup;
	fentry = debugfs_create_file("error_inject", S_IWUSR,
				     einj_debug_dir, NULL, &error_inject_fops);
	if (!fentry)
		goto err_cleanup;

	apei_resources_init(&einj_resources);
	einj_exec_ctx_init(&ctx);
	rc = apei_exec_collect_resources(&ctx, &einj_resources);
	if (rc)
		goto err_fini;
	rc = apei_resources_request(&einj_resources, "APEI EINJ");
	if (rc)
		goto err_fini;
	rc = apei_exec_pre_map_gars(&ctx);
	if (rc)
		goto err_release;
	if (param_extension) {
		param_paddr = einj_get_parameter_address();
		if (param_paddr) {
			einj_param = ioremap(param_paddr, sizeof(*einj_param));
			rc = -ENOMEM;
			if (!einj_param)
				goto err_unmap;
			fentry = debugfs_create_x64("param1", S_IRUSR | S_IWUSR,
						    einj_debug_dir, &error_param1);
			if (!fentry)
				goto err_unmap;
			fentry = debugfs_create_x64("param2", S_IRUSR | S_IWUSR,
						    einj_debug_dir, &error_param2);
			if (!fentry)
				goto err_unmap;
		} else
			pr_warn(EINJ_PFX "Parameter extension is not supported.\n");
	}

	pr_info(EINJ_PFX "Error INJection is initialized.\n");

	return 0;

err_unmap:
	if (einj_param)
		iounmap(einj_param);
	apei_exec_post_unmap_gars(&ctx);
err_release:
	apei_resources_release(&einj_resources);
err_fini:
	apei_resources_fini(&einj_resources);
err_cleanup:
	debugfs_remove_recursive(einj_debug_dir);

	return rc;
}

static void __exit einj_exit(void)
{
	struct apei_exec_context ctx;

	if (einj_param)
		iounmap(einj_param);
	einj_exec_ctx_init(&ctx);
	apei_exec_post_unmap_gars(&ctx);
	apei_resources_release(&einj_resources);
	apei_resources_fini(&einj_resources);
	debugfs_remove_recursive(einj_debug_dir);
}

module_init(einj_init);
module_exit(einj_exit);

MODULE_AUTHOR("Huang Ying");
MODULE_DESCRIPTION("APEI Error INJection support");
MODULE_LICENSE("GPL");