[PATCH v3] ACPI: sysfs: Enable ACPI sysfs support for CCEL records

[Kuppuswamy Sathyanarayanan]

The Confidential Computing Event Log (CCEL) table provides the address
and length of the CCEL records area in UEFI reserved memory.

To allow user space access to these records, expose a sysfs interface
similar to the BERT table.

More details about the CCEL table can be found in the ACPI specification
r6.5 [1], sec 5.2.34.

Link: https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html#cc-event-log-acpi-table # [1]
Co-developed-by: Haibo Xu <haibo1.xu@xxxxxxxxx>
Signed-off-by: Haibo Xu <haibo1.xu@xxxxxxxxx>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
---

Changes since v2:
 * Fixed the commit log as per review suggestion.

Changes since v1:
 * Removed unnecessary parenthesis as per Rafael's suggestion.

 drivers/acpi/sysfs.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c
index 7f4ff56c9d42..687524b50085 100644
--- a/drivers/acpi/sysfs.c
+++ b/drivers/acpi/sysfs.c
@@ -458,11 +458,28 @@ static int acpi_bert_data_init(void *th, struct acpi_data_attr *data_attr)
 	return sysfs_create_bin_file(tables_data_kobj, &data_attr->attr);
 }
 
+static int acpi_ccel_data_init(void *th, struct acpi_data_attr *data_attr)
+{
+	struct acpi_table_ccel *ccel = th;
+
+	if (ccel->header.length < sizeof(struct acpi_table_ccel) ||
+	    !ccel->log_area_start_address || !ccel->log_area_minimum_length) {
+		kfree(data_attr);
+		return -EINVAL;
+	}
+	data_attr->addr = ccel->log_area_start_address;
+	data_attr->attr.size = ccel->log_area_minimum_length;
+	data_attr->attr.attr.name = "CCEL";
+
+	return sysfs_create_bin_file(tables_data_kobj, &data_attr->attr);
+}
+
 static struct acpi_data_obj {
 	char *name;
 	int (*fn)(void *, struct acpi_data_attr *);
 } acpi_data_objs[] = {
 	{ ACPI_SIG_BERT, acpi_bert_data_init },
+	{ ACPI_SIG_CCEL, acpi_ccel_data_init },
 };
 
 #define NUM_ACPI_DATA_OBJS ARRAY_SIZE(acpi_data_objs)
-- 
2.34.1