Date:   Tue, 19 Apr 2022 09:38:57 -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 09/11] platform/x86/intel/ifs: Add IFS sysfs interface

From: Jithu Joseph <jithu.joseph@...el.com>

Implement sysfs interface to trigger ifs test for a specific cpu.
Additional interfaces related to checking the status of the
scan test and seeing the version of the loaded IFS binary
are also added.

The basic usage is as below.
   - To start test, for example on cpu5:
       echo 5 > /sys/devices/platform/intel_ifs/run_test
   - To see the status of the last test
       cat /sys/devices/platform/intel_ifs/status
   - To see the version of the loaded scan binary
       cat /sys/devices/platform/intel_ifs/image_version

Reviewed-by: Dan Williams <dan.j.williams@...el.com>
Signed-off-by: Jithu Joseph <jithu.joseph@...el.com>
Co-developed-by: Tony Luck <tony.luck@...el.com>
Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 drivers/platform/x86/intel/ifs/Makefile  |   2 +-
 drivers/platform/x86/intel/ifs/core.c    |   9 ++
 drivers/platform/x86/intel/ifs/ifs.h     |   3 +
 drivers/platform/x86/intel/ifs/runtest.c |   7 ++
 drivers/platform/x86/intel/ifs/sysfs.c   | 151 +++++++++++++++++++++++
 5 files changed, 171 insertions(+), 1 deletion(-)
 create mode 100644 drivers/platform/x86/intel/ifs/sysfs.c

diff --git a/drivers/platform/x86/intel/ifs/Makefile b/drivers/platform/x86/intel/ifs/Makefile
index 7de27361b479..dbbe0bf66987 100644
--- a/drivers/platform/x86/intel/ifs/Makefile
+++ b/drivers/platform/x86/intel/ifs/Makefile
@@ -2,4 +2,4 @@ obj-$(CONFIG_INTEL_IFS_DEVICE)	+= intel_ifs_device.o
 
 obj-$(CONFIG_INTEL_IFS)		+= intel_ifs.o
 
-intel_ifs-objs			:= core.o load.o runtest.o
+intel_ifs-objs			:= core.o load.o runtest.o sysfs.o
diff --git a/drivers/platform/x86/intel/ifs/core.c b/drivers/platform/x86/intel/ifs/core.c
index 0dc4cdda35ff..f56cde0cdfd6 100644
--- a/drivers/platform/x86/intel/ifs/core.c
+++ b/drivers/platform/x86/intel/ifs/core.c
@@ -3,6 +3,7 @@
 
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/semaphore.h>
 
 #include "ifs.h"
 
@@ -26,10 +27,18 @@ static int ifs_probe(struct platform_device *pdev)
 	return 0;
 }
 
+/*
+ * Note there is no need for a ->remove() call back. There isn't an
+ * "unload" operation to remove the scan binary from the BIOS reserved
+ * area. Also ".dev_groups" removal order will guarantee that any in
+ * flight tests have completed.
+ */
+
 static struct platform_driver intel_ifs_driver = {
 	.probe = ifs_probe,
 	.driver = {
 		.name = "intel_ifs",
+		.dev_groups = plat_ifs_groups,
 	},
 };
 
diff --git a/drivers/platform/x86/intel/ifs/ifs.h b/drivers/platform/x86/intel/ifs/ifs.h
index f5e3636d709f..4e6662f2d2f8 100644
--- a/drivers/platform/x86/intel/ifs/ifs.h
+++ b/drivers/platform/x86/intel/ifs/ifs.h
@@ -97,4 +97,7 @@ int ifs_setup_wq(void);
 void ifs_destroy_wq(void);
 int do_core_test(int cpu, struct device *dev);
 
+extern const struct attribute_group *plat_ifs_groups[];
+extern struct semaphore ifs_sem;
+
 #endif
diff --git a/drivers/platform/x86/intel/ifs/runtest.c b/drivers/platform/x86/intel/ifs/runtest.c
index 7793a01f7b94..246eff250563 100644
--- a/drivers/platform/x86/intel/ifs/runtest.c
+++ b/drivers/platform/x86/intel/ifs/runtest.c
@@ -10,6 +10,13 @@
 
 #include "ifs.h"
 
+/*
+ * Note all code and data in this file is protected by
+ * ifs_sem. On HT systems all threads on a core will
+ * execute together, but only the first thread on the
+ * core will update results of the test and indicate
+ * completion.
+ */
 static struct workqueue_struct *ifs_wq;
 static struct completion test_thread_done;
 static atomic_t siblings_in;
diff --git a/drivers/platform/x86/intel/ifs/sysfs.c b/drivers/platform/x86/intel/ifs/sysfs.c
new file mode 100644
index 000000000000..41db2a12fbc8
--- /dev/null
+++ b/drivers/platform/x86/intel/ifs/sysfs.c
@@ -0,0 +1,151 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2022 Intel Corporation. */
+
+#include <linux/cpu.h>
+#include <linux/delay.h>
+#include <linux/fs.h>
+#include <linux/platform_device.h>
+#include <linux/semaphore.h>
+#include <linux/slab.h>
+
+#include "ifs.h"
+
+/*
+ * Protects against simultaneous tests on multiple cores, or
+ * reloading can file while a test is in progress
+ */
+DEFINE_SEMAPHORE(ifs_sem);
+
+/*
+ * The sysfs interface to check additional details of last test
+ * cat /sys/devices/system/platform/ifs/details
+ */
+static ssize_t details_show(struct device *dev,
+			    struct device_attribute *attr,
+			    char *buf)
+{
+	struct ifs_data *ifsd = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%#llx\n", ifsd->scan_details);
+}
+
+static DEVICE_ATTR_RO(details);
+
+static const char * const status_msg[] = {
+	[SCAN_NOT_TESTED] = "untested",
+	[SCAN_TEST_PASS] = "pass",
+	[SCAN_TEST_FAIL] = "fail"
+};
+
+/*
+ * The sysfs interface to check the test status:
+ * To check the status of last test
+ * cat /sys/devices/platform/ifs/status
+ */
+static ssize_t status_show(struct device *dev,
+			   struct device_attribute *attr,
+			   char *buf)
+{
+	struct ifs_data *ifsd = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%s\n", status_msg[ifsd->status]);
+}
+
+static DEVICE_ATTR_RO(status);
+
+/*
+ * The sysfs interface for single core testing
+ * To start test, for example, cpu5
+ * echo 5 > /sys/devices/platform/ifs/run_test
+ * To check the result:
+ * cat /sys/devices/platform/ifs/result
+ * The sibling core gets tested at the same time.
+ */
+static ssize_t run_test_store(struct device *dev,
+			      struct device_attribute *attr,
+			      const char *buf, size_t count)
+{
+	struct ifs_data *ifsd = dev_get_drvdata(dev);
+	unsigned int cpu;
+	int rc;
+
+	rc = kstrtouint(buf, 0, &cpu);
+	if (rc < 0 || cpu >= nr_cpu_ids)
+		return -EINVAL;
+
+	if (down_interruptible(&ifs_sem))
+		return -EINTR;
+
+	if (!ifsd->loaded)
+		rc = -EPERM;
+	else
+		rc = do_core_test(cpu, dev);
+
+	up(&ifs_sem);
+
+	return rc ? rc : count;
+}
+
+static DEVICE_ATTR_WO(run_test);
+
+/*
+ * Reload the IFS image. When user wants to install new IFS image
+ */
+static ssize_t reload_store(struct device *dev,
+			    struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	struct ifs_data *ifsd = dev_get_drvdata(dev);
+	int rc;
+
+	if (!sysfs_streq(buf, "1"))
+		return -EINVAL;
+
+	if (down_interruptible(&ifs_sem))
+		return -EINTR;
+
+	rc = load_ifs_binary(dev);
+
+	ifsd->loaded = (rc == 0);
+
+	up(&ifs_sem);
+
+	return rc ? rc : count;
+}
+
+static DEVICE_ATTR_WO(reload);
+
+/*
+ * Display currently loaded IFS image version.
+ */
+static ssize_t image_version_show(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	struct ifs_data *ifsd = dev_get_drvdata(dev);
+
+	if (!ifsd->loaded)
+		return sysfs_emit(buf, "%s\n", "none");
+	else
+		return sysfs_emit(buf, "%#x\n", ifsd->loaded_version);
+}
+
+static DEVICE_ATTR_RO(image_version);
+
+/* global scan sysfs attributes */
+static struct attribute *plat_ifs_attrs[] = {
+	&dev_attr_details.attr,
+	&dev_attr_status.attr,
+	&dev_attr_run_test.attr,
+	&dev_attr_reload.attr,
+	&dev_attr_image_version.attr,
+	NULL
+};
+
+static const struct attribute_group plat_ifs_attr_group = {
+	.attrs = plat_ifs_attrs,
+};
+
+const struct attribute_group *plat_ifs_groups[] = {
+	&plat_ifs_attr_group,
+	NULL
+};
-- 
2.35.1

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