platform/x86/amd/hsmp: Check HSMP support on AMD family of processors

HSMP interface is supported only on few x86 processors from AMD.
Accessing HSMP registers on rest of the platforms might cause
unexpected behaviour. So add a check.

Also unavailability of this interface on rest of the processors
is not an error. Hence, use pr_info() instead of the pr_err() to
log the message.

Signed-off-by: Suma Hegde <[e-mail]>
Reviewed-by: Naveen Krishna Chatradhi <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Hans de Goede <[e-mail]>
Signed-off-by: Hans de Goede <[e-mail]>

drivers/platform/x86/amd/hsmp.c

···
 	return ret;
 }
 
+/*
+ * This check is only needed for backward compatibility of previous platforms.
+ * All new platforms are expected to support ACPI based probing.
+ */
+static bool legacy_hsmp_support(void)
+{
+	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
+		return false;
+
+	switch (boot_cpu_data.x86) {
+	case 0x19:
+		switch (boot_cpu_data.x86_model) {
+		case 0x00 ... 0x1F:
+		case 0x30 ... 0x3F:
+		case 0x90 ... 0x9F:
+		case 0xA0 ... 0xAF:
+			return true;
+		default:
+			return false;
+		}
+	case 0x1A:
+		switch (boot_cpu_data.x86_model) {
+		case 0x00 ... 0x1F:
+			return true;
+		default:
+			return false;
+		}
+	default:
+		return false;
+	}
+
+	return false;
+}
+
 static int __init hsmp_plt_init(void)
 {
 	int ret = -ENODEV;
-
-	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD || boot_cpu_data.x86 < 0x19) {
-		pr_err("HSMP is not supported on Family:%x model:%x\n",
-		       boot_cpu_data.x86, boot_cpu_data.x86_model);
-		return ret;
-	}
 
 	/*
 	 * amd_nb_num() returns number of SMN/DF interfaces present in the system
···
 		return ret;
 
 	if (!plat_dev.is_acpi_device) {
-		ret = hsmp_plat_dev_register();
+		if (legacy_hsmp_support()) {
+			/* Not ACPI device, but supports HSMP, register a plat_dev */
+			ret = hsmp_plat_dev_register();
+		} else {
+			/* Not ACPI, Does not support HSMP */
+			pr_info("HSMP is not supported on Family:%x model:%x\n",
+				boot_cpu_data.x86, boot_cpu_data.x86_model);
+			ret = -ENODEV;
+		}
 		if (ret)
 			platform_driver_unregister(&amd_hsmp_driver);
 	}