3 files changed, 42 insertions, 5 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 25d2c6f7325e..f1304d38aa21 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2375,12 +2375,9 @@ config X86_DMA_REMAP
         depends on STA2X11
 
 config IOSF_MBI
-        bool
+        tristate
+        default m
         depends on PCI
-        ---help---
-          To be selected by modules requiring access to the Intel OnChip System
-          Fabric (IOSF) Sideband MailBox Interface (MBI). For MBI platforms
-          enumerable by PCI.
 
 source "net/Kconfig"
 
diff --git a/arch/x86/include/asm/iosf_mbi.h b/arch/x86/include/asm/iosf_mbi.h
index 8e71c7941767..1a91a3698b1e 100644
--- a/arch/x86/include/asm/iosf_mbi.h
+++ b/arch/x86/include/asm/iosf_mbi.h
@@ -50,6 +50,10 @@
 #define BT_MBI_PCIE_READ        0x00
 #define BT_MBI_PCIE_WRITE       0x01
 
+#if IS_ENABLED(CONFIG_IOSF_MBI)
+
+bool iosf_mbi_available(void);
+
 /**
  * iosf_mbi_read() - MailBox Interface read command
  * @port:       port indicating subunit being accessed
@@ -87,4 +91,33 @@ int iosf_mbi_write(u8 port, u8 opcode, u32 offset, u32 mdr);
  */
 int iosf_mbi_modify(u8 port, u8 opcode, u32 offset, u32 mdr, u32 mask);
 
+#else /* CONFIG_IOSF_MBI is not enabled */
+static inline
+bool iosf_mbi_available(void)
+{
+        return false;
+}
+
+static inline
+int iosf_mbi_read(u8 port, u8 opcode, u32 offset, u32 *mdr)
+{
+        WARN(1, "IOSF_MBI driver not available");
+        return -EPERM;
+}
+
+static inline
+int iosf_mbi_write(u8 port, u8 opcode, u32 offset, u32 mdr)
+{
+        WARN(1, "IOSF_MBI driver not available");
+        return -EPERM;
+}
+
+static inline
+int iosf_mbi_modify(u8 port, u8 opcode, u32 offset, u32 mdr, u32 mask)
+{
+        WARN(1, "IOSF_MBI driver not available");
+        return -EPERM;
+}
+#endif /* CONFIG_IOSF_MBI */
+
 #endif /* IOSF_MBI_SYMS_H */
diff --git a/arch/x86/kernel/iosf_mbi.c b/arch/x86/kernel/iosf_mbi.c
index c3aae6672843..f4ff9786a620 100644
--- a/arch/x86/kernel/iosf_mbi.c
+++ b/arch/x86/kernel/iosf_mbi.c
@@ -177,6 +177,13 @@ int iosf_mbi_modify(u8 port, u8 opcode, u32 offset, u32 mdr, u32 mask)
 }
 EXPORT_SYMBOL(iosf_mbi_modify);
 
+bool iosf_mbi_available(void)
+{
+        /* Mbi isn't hot-pluggable. No remove routine is provided */
+        return mbi_pdev;
+}
+EXPORT_SYMBOL(iosf_mbi_available);
+
 static int iosf_mbi_probe(struct pci_dev *pdev,
                           const struct pci_device_id *unused)
 {