platform/x86/intel/ifs: Add current_batch sysfs entry

Initial implementation assumed a single IFS test image file with a
fixed name ff-mm-ss.scan. (where ff, mm, ss refers to family, model and
stepping of the core).

Subsequently, it became evident that supporting more than one test
image file is needed to provide more comprehensive test coverage. (Test
coverage in this scenario refers to testing more transistors in the core
to identify faults).

The other alternative of increasing the size of a single scan test image
file would not work as the  upper bound is limited by the size of memory
area reserved by BIOS for loading IFS test image.

Introduce "current_batch" file which accepts a number. Writing a
number to the current_batch file would load the test image file by
name ff-mm-ss-<xy>.scan, where <xy> is the number written to the
"current_batch" file in hex. Range check of the input is done to verify
it not greater than 0xff.

For e.g if the scan test image comprises of 6 files, they would be named:

  06-8f-06-01.scan
  06-8f-06-02.scan
  06-8f-06-03.scan
  06-8f-06-04.scan
  06-8f-06-05.scan
  06-8f-06-06.scan

And writing 3 to current_batch would result in loading 06-8f-06-03.scan
above. The file can also be read to know the currently loaded file.

And testing a system looks like:

  for each scan file
  do
  	load the IFS test image file (write to the batch file)
  	for each core
  	do
  		test the core with this set of tests
  	done
  done

Qualify few error messages with the test image file suffix to provide
better context.

  [ bp: Massage commit message. Add link to the discussion. ]

Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20221107225323.2733518-13-jithu.joseph@intel.com

1 files changed, 38 insertions, 0 deletions

diff --git a/drivers/platform/x86/intel/ifs/sysfs.c b/drivers/platform/x86/intel/ifs/sysfs.c
index e077910c5d28..ee636a76b083 100644
--- a/drivers/platform/x86/intel/ifs/sysfs.c
+++ b/drivers/platform/x86/intel/ifs/sysfs.c
@@ -87,6 +87,43 @@ static ssize_t run_test_store(struct device *dev,
 
 static DEVICE_ATTR_WO(run_test);
 
+static ssize_t current_batch_store(struct device *dev,
+				   struct device_attribute *attr,
+				   const char *buf, size_t count)
+{
+	struct ifs_data *ifsd = ifs_get_data(dev);
+	unsigned int cur_batch;
+	int rc;
+
+	rc = kstrtouint(buf, 0, &cur_batch);
+	if (rc < 0 || cur_batch > 0xff)
+		return -EINVAL;
+
+	if (down_interruptible(&ifs_sem))
+		return -EINTR;
+
+	ifsd->cur_batch = cur_batch;
+
+	rc = ifs_load_firmware(dev);
+
+	up(&ifs_sem);
+
+	return (rc == 0) ? count : rc;
+}
+
+static ssize_t current_batch_show(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	struct ifs_data *ifsd = ifs_get_data(dev);
+
+	if (!ifsd->loaded)
+		return sysfs_emit(buf, "none\n");
+	else
+		return sysfs_emit(buf, "0x%02x\n", ifsd->cur_batch);
+}
+
+static DEVICE_ATTR_RW(current_batch);
+
 /*
  * Display currently loaded IFS image version.
  */
@@ -108,6 +145,7 @@ static struct attribute *plat_ifs_attrs[] = {
 	&dev_attr_details.attr,
 	&dev_attr_status.attr,
 	&dev_attr_run_test.attr,
+	&dev_attr_current_batch.attr,
 	&dev_attr_image_version.attr,
 	NULL
 };