[PATCH v3 04/11] platform/x86/intel/ifs: Add stub driver for In-Field Scan

[Tony Luck <tony.luck@intel.com>]

Cloud Service Providers that operate fleets of servers have reported
[1] occasions where they can detect that a CPU has gone bad due to
effects like electromigration, or isolated manufacturing defects.
However, that detection method is A/B testing seemingly random
application failures looking for a pattern. In-Field Scan (IFS) is
a driver for a platform capability to load a crafted 'scan image'
to run targeted low level diagnostics outside of the CPU's architectural
error detection capabilities.

[1]: https://www.youtube.com/watch?v=QMF3rqhjYuM

Kconfig for this driver selects CONFIG_INTEL_IFS_DEVICE so the base
kernel will be built with code to create the device to which this driver
will attach.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

---
Not using module_platform_driver() for this simple stub because
later patches need to add init()/exit() functions.
---
 drivers/platform/x86/intel/ifs/Kconfig  | 14 ++++++++++++
 drivers/platform/x86/intel/ifs/Makefile |  4 ++++
 drivers/platform/x86/intel/ifs/core.c   | 29 +++++++++++++++++++++++++
 3 files changed, 47 insertions(+)
 create mode 100644 drivers/platform/x86/intel/ifs/core.c

diff --git a/drivers/platform/x86/intel/ifs/Kconfig b/drivers/platform/x86/intel/ifs/Kconfig
index 51325b699563..0aa5ecc5ef42 100644
--- a/drivers/platform/x86/intel/ifs/Kconfig
+++ b/drivers/platform/x86/intel/ifs/Kconfig
@@ -1,2 +1,16 @@
 config INTEL_IFS_DEVICE
 	bool
+
+config INTEL_IFS
+	tristate "Intel In Field Scan"
+	depends on X86 && 64BIT && SMP
+	select INTEL_IFS_DEVICE
+	help
+	  Enable support for the In Field Scan capability in select
+	  CPUs. The capability allows for running low level tests via
+	  a scan image distributed by Intel via Github to validate CPU
+	  operation beyond baseline RAS capabilities. To compile this
+	  driver as a module, choose M here. The module will be called
+	  intel_ifs.
+
+	  If unsure, say N.
diff --git a/drivers/platform/x86/intel/ifs/Makefile b/drivers/platform/x86/intel/ifs/Makefile
index 12c2f5ce9925..bf8adc57892c 100644
--- a/drivers/platform/x86/intel/ifs/Makefile
+++ b/drivers/platform/x86/intel/ifs/Makefile
@@ -1 +1,5 @@
 obj-$(CONFIG_INTEL_IFS_DEVICE)	+= intel_ifs_device.o
+
+obj-$(CONFIG_INTEL_IFS)		+= intel_ifs.o
+
+intel_ifs-objs			:= core.o
diff --git a/drivers/platform/x86/intel/ifs/core.c b/drivers/platform/x86/intel/ifs/core.c
new file mode 100644
index 000000000000..eb34b877dac0
--- /dev/null
+++ b/drivers/platform/x86/intel/ifs/core.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2022 Intel Corporation. */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+static struct platform_driver intel_ifs_driver = {
+	.driver = {
+		.name = "intel_ifs",
+	},
+};
+
+static int __init ifs_init(void)
+{
+	return platform_driver_register(&intel_ifs_driver);
+}
+
+static void __exit ifs_exit(void)
+{
+	platform_driver_unregister(&intel_ifs_driver);
+}
+
+module_init(ifs_init);
+module_exit(ifs_exit);
+
+MODULE_ALIAS("platform:intel_ifs*");
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Intel In Field Scan (IFS) driver");
-- 
2.35.1