linux-kernel - [PATCH v3 03/11] platform/x86/intel/ifs: Create device for Intel IFS (In Field Scan)

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Date:   Tue, 19 Apr 2022 09:38:51 -0700
From:   Tony Luck <tony.luck@...el.com>
To:     hdegoede@...hat.com, markgross@...nel.org
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
        corbet@....net, gregkh@...uxfoundation.org,
        andriy.shevchenko@...ux.intel.com, jithu.joseph@...el.com,
        ashok.raj@...el.com, tony.luck@...el.com, rostedt@...dmis.org,
        dan.j.williams@...el.com, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        patches@...ts.linux.dev, ravi.v.shankar@...el.com
Subject: [PATCH v3 03/11] platform/x86/intel/ifs: Create device for Intel IFS (In Field Scan)

The initial implementation of IFS is model specific. Enumeration is
via a combination of family-model-stepping and a check for a bit in the
CORE_CAPABILITIES MSR.

Linux has handled this lack of enumeration before with a code stub to
create a device.  See arch/x86/kernel/pmem.c. Use the same approach
here.

Reviewed-by: Dan Williams <dan.j.williams@...el.com>
Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 MAINTAINERS                                   |  7 +++
 drivers/platform/x86/intel/Kconfig            |  1 +
 drivers/platform/x86/intel/Makefile           |  1 +
 drivers/platform/x86/intel/ifs/Kconfig        |  2 +
 drivers/platform/x86/intel/ifs/Makefile       |  1 +
 .../platform/x86/intel/ifs/intel_ifs_device.c | 50 +++++++++++++++++++
 6 files changed, 62 insertions(+)
 create mode 100644 drivers/platform/x86/intel/ifs/Kconfig
 create mode 100644 drivers/platform/x86/intel/ifs/Makefile
 create mode 100644 drivers/platform/x86/intel/ifs/intel_ifs_device.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 40fa1955ca3f..9e372a960fa5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9861,6 +9861,13 @@ B:	https://bugzilla.kernel.org
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux.git
 F:	drivers/idle/intel_idle.c
 
+INTEL IN FIELD SCAN (IFS) DRIVER
+M:	Jithu Joseph <jithu.joseph@...el.com>
+R:	Ashok Raj <ashok.raj@...el.com>
+R:	Tony Luck <tony.luck@...el.com>
+S:	Maintained
+F:	drivers/platform/x86/intel/ifs
+
 INTEL INTEGRATED SENSOR HUB DRIVER
 M:	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
 M:	Jiri Kosina <jikos@...nel.org>
diff --git a/drivers/platform/x86/intel/Kconfig b/drivers/platform/x86/intel/Kconfig
index 1f01a8a23c57..794968bda115 100644
--- a/drivers/platform/x86/intel/Kconfig
+++ b/drivers/platform/x86/intel/Kconfig
@@ -4,6 +4,7 @@
 #
 
 source "drivers/platform/x86/intel/atomisp2/Kconfig"
+source "drivers/platform/x86/intel/ifs/Kconfig"
 source "drivers/platform/x86/intel/int1092/Kconfig"
 source "drivers/platform/x86/intel/int3472/Kconfig"
 source "drivers/platform/x86/intel/pmc/Kconfig"
diff --git a/drivers/platform/x86/intel/Makefile b/drivers/platform/x86/intel/Makefile
index c61bc3e97121..10285d0fd16a 100644
--- a/drivers/platform/x86/intel/Makefile
+++ b/drivers/platform/x86/intel/Makefile
@@ -5,6 +5,7 @@
 #
 
 obj-$(CONFIG_INTEL_ATOMISP2_PDX86)	+= atomisp2/
+obj-y					+= ifs/
 obj-$(CONFIG_INTEL_SAR_INT1092)		+= int1092/
 obj-$(CONFIG_INTEL_SKL_INT3472)		+= int3472/
 obj-$(CONFIG_INTEL_PMC_CORE)		+= pmc/
diff --git a/drivers/platform/x86/intel/ifs/Kconfig b/drivers/platform/x86/intel/ifs/Kconfig
new file mode 100644
index 000000000000..51325b699563
--- /dev/null
+++ b/drivers/platform/x86/intel/ifs/Kconfig
@@ -0,0 +1,2 @@
+config INTEL_IFS_DEVICE
+	bool
diff --git a/drivers/platform/x86/intel/ifs/Makefile b/drivers/platform/x86/intel/ifs/Makefile
new file mode 100644
index 000000000000..12c2f5ce9925
--- /dev/null
+++ b/drivers/platform/x86/intel/ifs/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_INTEL_IFS_DEVICE)	+= intel_ifs_device.o
diff --git a/drivers/platform/x86/intel/ifs/intel_ifs_device.c b/drivers/platform/x86/intel/ifs/intel_ifs_device.c
new file mode 100644
index 000000000000..64a143871d72
--- /dev/null
+++ b/drivers/platform/x86/intel/ifs/intel_ifs_device.c
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright(c) 2022 Intel Corporation. */
+
+#include <linux/platform_device.h>
+#include <linux/init.h>
+#include <asm/cpu_device_id.h>
+
+#define MSR_IA32_CORE_CAPS_INTEGRITY_BIT	2
+#define MSR_IA32_CORE_CAPS_INTEGRITY		BIT(MSR_IA32_CORE_CAPS_INTEGRITY_BIT)
+
+#define X86_MATCH(model)					\
+	X86_MATCH_VENDOR_FAM_MODEL_FEATURE(INTEL, 6,		\
+		INTEL_FAM6_##model, X86_FEATURE_CORE_CAPABILITIES, NULL)
+
+static const struct x86_cpu_id ifs_cpu_ids[] __initconst = {
+	X86_MATCH(SAPPHIRERAPIDS_X),
+	{}
+};
+
+static __init int register_ifs_device(void)
+{
+	struct platform_device *pdev;
+	const struct x86_cpu_id *m;
+	u64 ia32_core_caps;
+
+	m = x86_match_cpu(ifs_cpu_ids);
+	if (!m)
+		return -ENODEV;
+
+	if (rdmsrl_safe(MSR_IA32_CORE_CAPS, &ia32_core_caps))
+		return -ENODEV;
+
+	if (ia32_core_caps & MSR_IA32_CORE_CAPS_INTEGRITY) {
+		pdev = platform_device_alloc("intel_ifs", 0);
+		if (pdev) {
+			if (platform_device_add(pdev))
+				platform_device_put(pdev);
+		}
+	}
+
+	/*
+	 * Failure here will be visible by a missing device
+	 * in sysfs. Returning an error code would not make
+	 * that any easier to diagnose. Would also complicate
+	 * future implementations that may support a subset of
+	 * the types of tests.
+	 */
+	return 0;
+}
+device_initcall(register_ifs_device);
-- 
2.35.1