[PATCH 3/6] powercap: intel_rapl_tpmi: Ignore minor version change

[Zhang Rui <rui.zhang@intel.com>]

The hardware definition of every TPMI feature contains a major and minor
version. When there is a change in the MMIO offset or change in the
definition of a field, hardware will change major version. For addition
of new fields without modifying existing MMIO offsets or fields, only the
minor version is changed.

Driver is developed to support RAPL functionality for a major and minor
version. If the hardware changes major version, since offsets and
definitions are changed, driver cannot continue to provide RAPL interface
to users. Driver can still function with a minor version change as it will
just miss the new functionality added by the hardware. The current
implementation doesn't ignore any version change.

If there is mismatch with the minor version, continue with an information
log message. If there is mismatch with the major version, log error and
exit.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
---
 drivers/powercap/intel_rapl_tpmi.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/powercap/intel_rapl_tpmi.c b/drivers/powercap/intel_rapl_tpmi.c
index 7435df083ea4..645fd1dc51a9 100644
--- a/drivers/powercap/intel_rapl_tpmi.c
+++ b/drivers/powercap/intel_rapl_tpmi.c
@@ -15,7 +15,8 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 
-#define TPMI_RAPL_VERSION 1
+#define TPMI_RAPL_MAJOR_VERSION 0
+#define TPMI_RAPL_MINOR_VERSION 1
 
 /* 1 header + 10 registers + 5 reserved. 8 bytes for each. */
 #define TPMI_RAPL_DOMAIN_SIZE 128
@@ -154,11 +155,21 @@ static int parse_one_domain(struct tpmi_rapl_package *trp, u32 offset)
 	tpmi_domain_size = tpmi_domain_header >> 16 & 0xff;
 	tpmi_domain_flags = tpmi_domain_header >> 32 & 0xffff;
 
-	if (tpmi_domain_version != TPMI_RAPL_VERSION) {
-		pr_warn(FW_BUG "Unsupported version:%d\n", tpmi_domain_version);
+	if (tpmi_domain_version == TPMI_VERSION_INVALID) {
+		pr_warn(FW_BUG "Invalid version\n");
 		return -ENODEV;
 	}
 
+	if (TPMI_MAJOR_VERSION(tpmi_domain_version) != TPMI_RAPL_MAJOR_VERSION) {
+		pr_warn(FW_BUG "Unsupported major version:%ld\n",
+			TPMI_MAJOR_VERSION(tpmi_domain_version));
+		return -ENODEV;
+	}
+
+	if (TPMI_MINOR_VERSION(tpmi_domain_version) > TPMI_RAPL_MINOR_VERSION)
+		pr_info("Ignore: Unsupported minor version:%ld\n",
+			TPMI_MINOR_VERSION(tpmi_domain_version));
+
 	/* Domain size: in unit of 128 Bytes */
 	if (tpmi_domain_size != 1) {
 		pr_warn(FW_BUG "Invalid Domain size %d\n", tpmi_domain_size);
-- 
2.34.1