powercap: intel_rapl_tpmi: Fix System Domain probing

Only domain root packages can enumerate System (Psys) domain.
Whether a package is domain root or not is described in the Bit 0 of the
Domain Info register.

Add support for Domain Info register and fix the System domain probing
accordingly.

Fixes: 9eef7f9 ("powercap: intel_rapl: Introduce RAPL TPMI interface driver")
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Cc: 6.5+ <stable@vger.kernel.org> # 6.5+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: zhang-rui

drivers/powercap/intel_rapl_tpmi.c

@@ -131,6 +131,12 @@ static void trp_release(struct tpmi_rapl_package *trp)
 	mutex_unlock(&tpmi_rapl_lock);
 }
 
+/*
+ * Bit 0 of TPMI_RAPL_REG_DOMAIN_INFO indicates if the current package is a domain
+ * root or not. Only domain root packages can enumerate System (Psys) Domain.
+ */
+#define TPMI_RAPL_DOMAIN_ROOT	BIT(0)
+
 static int parse_one_domain(struct tpmi_rapl_package *trp, u32 offset)
 {
 	u8 tpmi_domain_version;
@@ -140,6 +146,7 @@ static int parse_one_domain(struct tpmi_rapl_package *trp, u32 offset)
 	enum rapl_domain_reg_id reg_id;
 	int tpmi_domain_size, tpmi_domain_flags;
 	u64 tpmi_domain_header = readq(trp->base + offset);
+	u64 tpmi_domain_info;
 
 	/* Domain Parent bits are ignored for now */
 	tpmi_domain_version = tpmi_domain_header & 0xff;
@@ -170,6 +177,13 @@ static int parse_one_domain(struct tpmi_rapl_package *trp, u32 offset)
 		domain_type = RAPL_DOMAIN_PACKAGE;
 		break;
 	case TPMI_RAPL_DOMAIN_SYSTEM:
+		if (!(tpmi_domain_flags & BIT(TPMI_RAPL_REG_DOMAIN_INFO))) {
+			pr_warn(FW_BUG "System domain must support Domain Info register\n");
+			return -ENODEV;
+		}
+		tpmi_domain_info = readq(trp->base + offset + TPMI_RAPL_REG_DOMAIN_INFO);
+		if (!(tpmi_domain_info & TPMI_RAPL_DOMAIN_ROOT))
+			return 0;
 		domain_type = RAPL_DOMAIN_PLATFORM;
 		break;
 	case TPMI_RAPL_DOMAIN_MEMORY: