Message-Id: <1419873783-5161-2-git-send-email-pure.logic@nexus-software.ie>
Date:	Mon, 29 Dec 2014 17:23:02 +0000
From:	Bryan O'Donoghue <pure.logic@...us-software.ie>
To:	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	x86@...nel.org, dvhart@...radead.org,
	platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	Bryan O'Donoghue <pure.logic@...us-software.ie>
Subject: [PATCH 1/2] x86: Add Isolated Memory Regions for Quark X1000

Intel's Quark X1000 SoC contains a set of registers called Isolated Memory
Regions. IMRs are accessed over the IOSF mailbox interface. IMRs are areas
carved out of memory that define read/write access rights to the various
system agents within the Quark system. For a given agent in the system it is
possible to specify if that agent may read or write an area of memory
defined by an IMR with a granularity of 1 kilobyte.

Quark_SecureBootPRM_330234_001.pdf section 4.5 details the concept of IMRs

eSRAM flush, CPU Snoop, CPU SMM Mode, CPU non-SMM mode, PMU and VC0/VC1 can
have individual read/write access masks applied to them for a given memory
region in Quark X1000. Quark supports eightIMR sets.

Since all of the DMA capable SoC components in the X1000 are mapped to VC0
it is possible to define sections of memory as invalid for DMA write
operations originating from Ethernet, USB, SD and any other DMA capable
south-cluster component on VC0. Similarly it is possible to mark kernel
memory as non-SMM mode read/write only or to mark BIOS runtime memory as SMM
mode accessible only depending on the particular memory footprint on a given
system.

On an IMR violation Quark SoC X1000 systems are configured to reset the
system, so ensuring that the IMR memory map agrees with the EFI provided
memory map is critical to ensure no IMR violations reset the system.

The API for accessing IMRs is based on MTRR code but doesn't provide a /proc
or /sys interface to manipulate IMRs. Defining the size and extent of IMRs
is exclusively the domain of in-kernel code.

Signed-off-by: Bryan O'Donoghue <pure.logic@...us-software.ie>
---
 arch/x86/Kconfig                   |  23 ++
 arch/x86/include/asm/imr.h         |  79 ++++++
 arch/x86/include/asm/intel-quark.h |  31 +++
 arch/x86/kernel/Makefile           |   1 +
 arch/x86/kernel/imr.c              | 529 +++++++++++++++++++++++++++++++++++++
 5 files changed, 663 insertions(+)
 create mode 100644 arch/x86/include/asm/imr.h
 create mode 100644 arch/x86/include/asm/intel-quark.h
 create mode 100644 arch/x86/kernel/imr.c

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ba397bd..8303ca2 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -526,6 +526,29 @@ config IOSF_MBI_DEBUG
 
 	  If you don't require the option or are in doubt, say N.
 
+config IMR
+	tristate "Isolated Memory Region support"
+	default m
+	depends on IOSF_MBI
+	---help---
+	  This option enables support for Isolated Memory Regions.
+	  IMRs are a set of registers that define read and write access masks
+	  to prohibit certain system agents from accessing memory with 1k
+	  granularity.
+	  IMRs make it possible to control read/write access to an address
+	  by hardware agents inside the SoC. Read and write masks can be
+	  defined for
+		- SMM mode
+		- Non SMM mode
+		- PCI VC0/VC1
+		- CPU snoop
+		- eSRAM flush
+		- PMU access
+	  Quark contains a set of IMR registers and makes use of those
+	  registers during it's bootup process.
+
+	  If you are running on a Galileo/Quark say Y here
+
 config X86_RDC321X
 	bool "RDC R-321x SoC"
 	depends on X86_32
diff --git a/arch/x86/include/asm/imr.h b/arch/x86/include/asm/imr.h
new file mode 100644
index 0000000..fe8f3b8
--- /dev/null
+++ b/arch/x86/include/asm/imr.h
@@ -0,0 +1,79 @@
+/*
+ * imr.h: Isolated Memory Region API
+ *
+ * Copyright(c) 2013 Intel Corporation.
+ * Copyright(c) 2014 Bryan O'Donoghue <pure.logic@...us-software.ie>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ */
+#ifndef _IMR_H
+#define _IMR_H
+
+#include <asm/intel-quark.h>
+#include <linux/types.h>
+
+/*
+ * Right now IMRs are not reported via CPUID though it'd be really great if
+ * future silicon did report via CPUID for this feature bringing it in-line with
+ * other similar features - like MTRRs, MSRs etc.
+ *
+ * A macro is defined here which is an analog to the other cpu_has_x type
+ * features
+ */
+#define cpu_has_imr cpu_is_quark
+
+/* IMR agent access mask bits */
+#define IMR_ESRAM_FLUSH		0x80000000
+#define IMR_CPU_SNOOP		0x40000000
+#define IMR_HB_ACCESS		0x20000000
+#define IMR_VC1_ID3		0x00008000
+#define IMR_VC1_ID2		0x00004000
+#define IMR_VC1_ID1		0x00002000
+#define IMR_VC1_ID0		0x00001000
+#define IMR_VC0_ID3		0x00000800
+#define IMR_VC0_ID2		0x00000400
+#define IMR_VC0_ID1		0x00000200
+#define IMR_VC0_ID0		0x00000100
+#define IMR_SMM			0x00000002
+#define IMR_NON_SMM		0x00000001
+#define IMR_ACCESS_NONE		0x00000000
+
+/* Definition of read/write masks from published BSP code */
+#define IMR_READ_ACCESS_ALL	0xBFFFFFFF
+#define IMR_WRITE_ACCESS_ALL	0xFFFFFFFF
+
+/* Number of IMRs provided by Quark X1000 SoC */
+#define QUARK_X1000_IMR_NUM	0x07
+#define QUARK_X1000_IMR_REGBASE 0x40
+
+/* IMR alignment bits - only bits 31:10 are checked for IMR validity */
+#define IMR_ALIGN		0x400
+#define IMR_MASK		(IMR_ALIGN - 1)
+
+/**
+ * imr_add_range - Add an Isolated Memory Region
+ * @base: Physical base address of region aligned to 4k
+ * @size: Physical size of region in bytes
+ * @read_mask: Read access mask
+ * @write_mask: Write access mask
+ * @lock: Indicates whether or not to permenantly lock this region
+ * @return: Index of the IMR allocated or negative value indicating error
+ */
+int imr_add(unsigned long base, unsigned long size,
+	    unsigned int rmask, unsigned int wmask, bool lock);
+
+/**
+ * imr_del_range - Delete an Isolated Memory Region
+ * @reg: IMR index to remove
+ * @base: Physical base address of region aligned to 4k
+ * @size: Physical size of region in bytes
+ * @return:	-EINVAL on invalid range or out or range id
+ *		-ENODEV if reg is valid but no IMR exists or is locked
+ *		0 on success
+ */
+int imr_del(int reg, unsigned long base, unsigned long size);
+
+#endif /* _IMR_H */
diff --git a/arch/x86/include/asm/intel-quark.h b/arch/x86/include/asm/intel-quark.h
new file mode 100644
index 0000000..f51ac8c
--- /dev/null
+++ b/arch/x86/include/asm/intel-quark.h
@@ -0,0 +1,31 @@
+/*
+ * intel-quark.h: Quark shared defines and helper functions
+ *
+ * Copyright 2014 Bryan O'Donoghue <pure.logic@...us-software.ie>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ */
+
+#ifndef _ASM_X86_INTEL_QUARK_H
+#define _ASM_X86_INTEL_QUARK_H
+
+#include <asm/processor.h>
+
+#ifdef CONFIG_X86_32
+static inline int cpu_is_quark(const struct cpuinfo_x86 *c)
+{
+	return (c->x86_vendor == X86_VENDOR_INTEL &&
+		c->x86 == 5 && c->x86_model == 9);
+}
+#else
+static inline int cpu_is_quark(const struct cpuinfo_x86 *c)
+{
+	return 0;
+}
+#endif
+
+#endif /* _ASM_X86_INTEL_QUARK_H */
+
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 5d4502c..0252de5 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -104,6 +104,7 @@ obj-$(CONFIG_EFI)			+= sysfb_efi.o
 obj-$(CONFIG_PERF_EVENTS)		+= perf_regs.o
 obj-$(CONFIG_TRACING)			+= tracepoint.o
 obj-$(CONFIG_IOSF_MBI)			+= iosf_mbi.o
+obj-$(CONFIG_IMR)			+= imr.o
 obj-$(CONFIG_PMC_ATOM)			+= pmc_atom.o
 
 ###
diff --git a/arch/x86/kernel/imr.c b/arch/x86/kernel/imr.c
new file mode 100644
index 0000000..4115138
--- /dev/null
+++ b/arch/x86/kernel/imr.c
@@ -0,0 +1,529 @@
+/**
+ * intel_imr.c
+ *
+ * Copyright(c) 2013 Intel Corporation.
+ * Copyright(c) 2014 Bryan O'Donoghue <pure.logic@...us-software.ie>
+ *
+ * IMR registers define an isolated region of memory that can
+ * be masked to prohibit certain system agents from accessing memory.
+ * When a device behind a masked port performs an access - snooped or not, an
+ * IMR may optionally prevent that transaction from changing the state of memory
+ * or from getting correct data in response to the operation.
+ * Write data will be dropped and reads will return 0xFFFFFFFF, the system will
+ * reset and system BIOS will print out an error message to inform the user that
+ * an IMR has been violated.
+ * This code is based on the Linux MTRR code and refernece code from Intel's
+ * Quark BSP EFI, Linux and grub code.
+ */
+#include <asm/intel-quark.h>
+#include <asm/imr.h>
+#include <asm/iosf_mbi.h>
+#include <linux/debugfs.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+struct imr_device {
+	struct dentry	*debugfs_dir;
+	struct mutex	lock;
+	int		num;
+	int		used;
+	int		reg_base;
+};
+
+static struct imr_device imr_dev;
+
+/**
+ * Values derived from published code in Quark BSP
+ *
+ * addr_lo
+ * 31		Lock bit
+ * 30		Enable bit - not implemented on Quark X1000
+ * 29:25	Reserved
+ * 24:2		1 kilobyte aligned lo address
+ * 1:0		Reserved
+ *
+ * addr_hi
+ * 31:25	Reserved
+ * 24:2		1 kilobyte aligned hi address
+ * 1:0		Reserved
+ */
+#define IMR_LOCK	0x80000000
+#define IMR_ENABLE	0x04000000
+
+struct imr {
+	u32 addr_lo;
+	u32 addr_hi;
+	u32 rmask;
+	u32 wmask;
+};
+
+#define IMR_NUM_REGS	(sizeof(struct imr)/sizeof(u32))
+#define IMR_SHIFT	8
+#define imr_to_phys(x)	(x << IMR_SHIFT)
+#define phys_to_imr(x)	(x >> IMR_SHIFT)
+
+/**
+ * imr_enabled
+ * Determines if an IMR is enabled based on address range
+ *
+ * @imr:	Pointer to IMR descriptor
+ * @return	true if IMR enabled false if disabled
+ */
+static int imr_enabled(struct imr *imr)
+{
+	return (imr_to_phys(imr->addr_lo) && imr_to_phys(imr->addr_hi));
+}
+
+/**
+ * imr_read
+ * Read an IMR at a given imr index. Requires caller to hold imr mutex
+ *
+ * @imr_id:	IMR entry to read
+ * @imr:	IMR structure representing address and access masks
+ * @return	0 on success or error code passed from mbi_iosf on failure
+ */
+static int imr_read(u32 imr_id, struct imr *imr)
+{
+	u32 reg = imr_dev.reg_base + (imr_id * IMR_NUM_REGS);
+	int ret;
+
+	ret = iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
+				reg, &imr->addr_lo);
+	if (ret)
+		return ret;
+
+	ret = iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
+				++reg, &imr->addr_hi);
+	if (ret)
+		return ret;
+
+	ret = iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
+				++reg, &imr->rmask);
+	if (ret)
+		return ret;
+
+	return iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
+				++reg, &imr->wmask);
+}
+
+/**
+ * imr_write
+ * Write an IMR at a given imr index. Requires caller to hold imr mutex
+ * Note lock bits need to be written independently of address bits
+ *
+ * @imr_id:	IMR entry to write
+ * @imr:	IMR structure representing address and access masks
+ * @lock:	Indicates if the IMR lock bit should be applied
+ * @return	0 on success or error code passed from mbi_iosf on failure
+ */
+static int imr_write(u32 imr_id, struct imr *imr, bool lock)
+{
+	unsigned long flags;
+	u32 reg = imr_dev.reg_base + (imr_id * IMR_NUM_REGS);
+	u32 reg_lock = reg;
+	int ret;
+
+	local_irq_save(flags);
+
+	ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE, reg,
+				imr->addr_lo);
+	if (ret)
+		goto done;
+
+	ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
+				++reg, imr->addr_hi);
+	if (ret)
+		goto done;
+
+	ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
+				++reg, imr->rmask);
+	if (ret)
+		goto done;
+
+	ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
+				++reg, imr->wmask);
+	if (ret)
+		goto done;
+
+	/* Lock bit must be set separately to addr_lo address bits */
+	if (lock) {
+		imr->addr_lo |= IMR_LOCK;
+		ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
+					reg_lock, imr->addr_lo);
+	}
+
+done:
+	local_irq_restore(flags);
+
+	/*
+	 * If writing to the IOSF failed then we're in an unknown state
+	 * likely a very bad state. An IMR in an invalid state will almost
+	 * certainly lead to a memory access violation.
+	 */
+	if (ret)
+		WARN(1, "IOSF-MBI write fail range 0x%08x-0x%08x unreliable\n",
+			imr_to_phys(imr->addr_lo),
+			imr_to_phys(imr->addr_hi) + IMR_MASK);
+
+	return ret;
+}
+
+#ifdef CONFIG_DEBUG_FS
+
+/**
+ * imr_dbgfs_state_show
+ * Print state of IMR registers
+ *
+ * @s:		pointer to seq_file for output
+ * @unused:	unused parameter
+ * @return	0 on success or error code passed from mbi_iosf on failure
+ */
+static int imr_dbgfs_state_show(struct seq_file *s, void *unused)
+{
+	int i, ret = -ENODEV;
+	struct imr imr;
+	u32 size;
+
+	mutex_lock(&imr_dev.lock);
+
+	for (i = 0; i <= imr_dev.num; i++) {
+
+		ret = imr_read(i, &imr);
+		if (ret)
+			break;
+
+		/*
+		 * Remember to add IMR_ALIGN bytes to size to indicate the
+		 * inherent IMR_ALIGN size bytes contained in the masked away
+		 * lower ten bits
+		 */
+		size = 0;
+		if (imr_enabled(&imr)) {
+			size = imr_to_phys(imr.addr_hi) -
+			       imr_to_phys(imr.addr_lo);
+			size += IMR_ALIGN;
+		}
+		seq_printf(s, "imr%02i: base=0x%08x, end=0x%08x, size=0x%08x "
+			   "rmask=0x%08x, wmask=0x%08x, %s, %s\n", i,
+			   imr_to_phys(imr.addr_lo),
+			   imr_to_phys(imr.addr_hi) + IMR_MASK, size,
+			   imr.rmask, imr.wmask,
+			   imr_enabled(&imr) ? "enabled " : "disabled",
+			   imr.addr_lo & IMR_LOCK ? "locked" : "unlocked");
+	}
+
+	mutex_unlock(&imr_dev.lock);
+
+	return ret;
+}
+
+/**
+ * imr_state_open
+ * Debugfs open callback
+ *
+ * @inode:	pointer to struct inode
+ * @file:	pointer to struct file
+ * @return	result of single open
+ */
+static int imr_state_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, imr_dbgfs_state_show, inode->i_private);
+}
+
+static const struct file_operations imr_state_ops = {
+	.open		= imr_state_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+/**
+ * imr_debugfs_register
+ * Register debugfs hooks
+ *
+ * @imr:	IMR structure representing address and access masks
+ * @return	0 on success - errno on failure
+ */
+static int imr_debugfs_register(struct imr_device *imr_dev)
+{
+	struct dentry *dir, *f;
+
+	dir = debugfs_create_dir("imr", NULL);
+	if (!dir)
+		return -ENOMEM;
+
+	f = debugfs_create_file("state", S_IFREG | S_IRUGO,
+				dir, imr_dev, &imr_state_ops);
+	if (!f)
+		goto err;
+
+	imr_dev->debugfs_dir = dir;
+
+	return 0;
+err:
+	return -ENODEV;
+}
+
+/**
+ * imr_debugfs_unregister
+ * Unregister debugfs hooks
+ *
+ * @imr:	IMR structure representing address and access masks
+ * @return	none
+ */
+static void imr_debugfs_unregister(struct imr_device *imr_dev)
+{
+	if (!imr_dev->debugfs_dir)
+		return;
+
+	debugfs_remove_recursive(imr_dev->debugfs_dir);
+	imr_dev->debugfs_dir = NULL;
+}
+
+#else
+
+/**
+ * imr_debugfs_register
+ * Register debugfs hooks
+ *
+ * @imr:	IMR structure representing address and access masks
+ * @return	0 on success - errno on failure
+ */
+static int imr_debugfs_register(struct imr_device *imr_dev)
+{
+	return 0;
+}
+
+/**
+ * imr_debugfs_unregister
+ * Dummy hook for !CONFIG_DEBUG_FS
+ *
+ * @imr:	IMR structure representing address and access masks
+ * @return	none
+ */
+static void imr_debugfs_unregister(struct imr_device *imr_dev)
+{
+}
+
+#endif /* CONFIG_DEBUG_FS */
+
+/**
+ * imr_check_range
+ * Check the passed address range for an IMR is aligned
+ *
+ * @base: base address of intended IMR
+ * @size: size of intended IMR
+ * @return zero on valid range -EINVAL on unaligned base/size
+ */
+static int imr_check_range(unsigned long base, unsigned long size)
+{
+	if ((base & (IMR_MASK)) || (size & (IMR_MASK))) {
+		pr_warn("imr: base 0x%08lx size 0x%08lx must align to 1k\n",
+			base, size);
+		dump_stack();
+		return -EINVAL;
+	}
+	return 0;
+}
+
+/**
+ * imr_add_range
+ * Add an Isolated Memory Region
+ *
+ * @base: Physical base address of region aligned to 4k
+ * @size: Physical size of region in bytes
+ * @read_mask: Read access mask
+ * @write_mask: Write access mask
+ * @lock: Indicates whether or not to permenantly lock this region
+ * @return: Index of the IMR allocated or negative value indicating error
+ */
+int imr_add(unsigned long base, unsigned long size,
+	    unsigned int rmask, unsigned int wmask, bool lock)
+{
+	unsigned long end = base + size;
+	struct imr imr;
+	int reg, i, overlap, ret;
+
+	if (imr_check_range(base, size))
+		return -EINVAL;
+
+	if (!size) {
+		pr_warn("imr: invalid size zero!\n");
+		return -EINVAL;
+	}
+
+	mutex_lock(&imr_dev.lock);
+
+	/* Find an free IMR while checking for an existing overlapping range */
+	overlap = 0;
+	reg = -1;
+	for (i = 0; i <= imr_dev.num; i++) {
+		ret = imr_read(i, &imr);
+		if (ret)
+			goto done;
+
+		/* Find overlap */
+		if (imr_enabled(&imr)) {
+			if (base >= imr_to_phys(imr.addr_lo) &&
+				base <= imr_to_phys(imr.addr_hi)) {
+				overlap = 1;
+				break;
+			}
+			if (end >= imr_to_phys(imr.addr_lo) &&
+				end <= imr_to_phys(imr.addr_hi)) {
+				overlap = 1;
+				break;
+			}
+		} else {
+			reg = i;
+		}
+	}
+
+	/* Error out if we have an overlap or no free IMR entries */
+	if (overlap) {
+		ret = -EINVAL;
+		goto done;
+	}
+	if (reg == -1) {
+		ret = -ENODEV;
+		goto done;
+	}
+
+	pr_debug("IMR %d phys 0x%08lx-0x%08lx rmask 0x%08x wmask 0x%08x\n",
+		reg, base, end, rmask, wmask);
+
+	/* Allocate IMR */
+	imr.addr_lo = IMR_ENABLE | phys_to_imr(base);
+	imr.addr_hi = phys_to_imr(end);
+	imr.rmask = rmask;
+	imr.wmask = wmask;
+
+	ret = imr_write(reg, &imr, lock);
+
+done:
+	mutex_unlock(&imr_dev.lock);
+	return ret;
+}
+EXPORT_SYMBOL(imr_add);
+
+/**
+ * imr_del_range
+ * Delete an Isolated Memory Region
+ *
+ * @reg: IMR index to remove
+ * @base: Physical base address of region aligned to 4k
+ * @size: Physical size of region in bytes
+ * @return:	-EINVAL on invalid range or out or range id
+ *		-ENODEV if reg is valid but no IMR exists or is locked
+ *		0 on success
+ */
+int imr_del(int reg, unsigned long base, unsigned long size)
+{
+	struct imr imr;
+	int found = 0, i, ret = 0;
+	unsigned long  max = base + size;
+
+	if (imr_check_range(base, size))
+		return -EINVAL;
+
+	if (reg > imr_dev.num)
+		return -EINVAL;
+
+	mutex_lock(&imr_dev.lock);
+
+	/* if a specific IMR is given try to use it */
+	if (reg >= 0) {
+		ret = imr_read(reg, &imr);
+		if (ret)
+			goto done;
+
+		if (!imr_enabled(&imr) || imr.addr_lo & IMR_LOCK) {
+			ret = -ENODEV;
+			goto done;
+		}
+		found = 1;
+	}
+
+	/* search for match based on address range */
+	for (i = 0; i <= imr_dev.num && found == 0; i++) {
+		ret = imr_read(reg, &imr);
+		if (ret)
+			goto done;
+
+		if (!imr_enabled(&imr) || imr.addr_lo & IMR_LOCK)
+			continue;
+
+		if ((imr_to_phys(imr.addr_lo) == base) &&
+		    (imr_to_phys(imr.addr_hi) == max)) {
+			found = 1;
+			reg = i;
+		}
+	}
+
+	if (found == 0) {
+		ret = -ENODEV;
+		goto done;
+	}
+
+	/* Tear down the IMR */
+	imr.addr_lo = 0;
+	imr.addr_hi = 0;
+	imr.rmask = IMR_READ_ACCESS_ALL;
+	imr.wmask = IMR_WRITE_ACCESS_ALL;
+
+	ret = imr_write(reg, &imr, false);
+
+done:
+	mutex_unlock(&imr_dev.lock);
+	return ret;
+}
+EXPORT_SYMBOL(imr_del);
+
+/**
+ * intel_imr_probe
+ * entry point for IMR driver
+ *
+ * return: -ENODEV for no IMR support 0 if good to go
+ */
+static int __init intel_imr_init(void)
+{
+	struct cpuinfo_x86 *c = &cpu_data(cpu);
+
+	if (!cpu_has_imr(c))
+		return -ENODEV;
+
+	if (iosf_mbi_available() == false)
+		return -ENODEV;
+
+	if (cpu_is_quark(c)) {
+		imr_dev.num = QUARK_X1000_IMR_NUM;
+		imr_dev.reg_base = QUARK_X1000_IMR_REGBASE;
+	} else {
+		pr_err("Unknown IMR implementation\n");
+		return -ENODEV;
+	}
+
+	mutex_init(&imr_dev.lock);
+
+	return imr_debugfs_register(&imr_dev);
+}
+
+/**
+ * intel_imr_exit
+ * exit point for IMR code. Deregisters debugfs, leave IMR state as-is.
+ *
+ * return: none
+ */
+static void __exit intel_imr_exit(void)
+{
+	imr_debugfs_unregister(&imr_dev);
+}
+
+module_init(intel_imr_init);
+module_exit(intel_imr_exit);
+
+MODULE_AUTHOR("Bryan O'Donoghue <pure.logic@...us-software.ie>");
+MODULE_DESCRIPTION("Intel Isolated Memory Region driver");
+MODULE_LICENSE("GPL");
-- 
1.9.1

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