[PATCH V2 3/3] x86: iosf: Add debugfs config option for iosf

["David E. Box" <david.e.box@linux.intel.com>]

Makes the iosf sideband available through debugfs. Allows developers to
experiment with using the sideband to provide debug and analytical tools for
units on the SoC.

Signed-off-by: David E. Box <david.e.box@linux.intel.com>
---
 arch/x86/Kconfig           | 13 +++++++++++++
 arch/x86/kernel/iosf_mbi.c | 23 +++++++++++++++++++----
 2 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index b075873..39489d6 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -497,6 +497,19 @@ config IOSF_MBI
 
 	  You should say Y if you are running a kernel on one of these SoC's.
 
+config IOSF_MBI_DEBUG
+	bool "Enable IOSF sideband access through debugfs"
+	depends on IOSF_MBI && DEBUG_FS
+	---help---
+	  Select this option to expose the IOSF sideband access registers (MCR,
+	  MDR, MCRX) through debugfs to write and read register information from
+	  different units on the SoC. This is most useful for obtaining device
+	  state information for debug and analysis. As this is a general access
+	  mechanism, users of this option would have specific knowledge of the
+	  device they want to access.
+
+	  If you don't require the option or are in doubt, say N.
+
 config X86_RDC321X
 	bool "RDC R-321x SoC"
 	depends on X86_32
diff --git a/arch/x86/kernel/iosf_mbi.c b/arch/x86/kernel/iosf_mbi.c
index e01f741..82f8d02 100644
--- a/arch/x86/kernel/iosf_mbi.c
+++ b/arch/x86/kernel/iosf_mbi.c
@@ -190,7 +190,7 @@ bool iosf_mbi_available(void)
 }
 EXPORT_SYMBOL(iosf_mbi_available);
 
-/********************** debugfs begin ****************************/
+#ifdef CONFIG_IOSF_MBI_DEBUG
 static u32	dbg_mdr;
 static u32	dbg_mcr;
 static u32	dbg_mcrx;
@@ -229,6 +229,7 @@ static int mcr_set(void *data, u64 val)
 DEFINE_SIMPLE_ATTRIBUTE(iosf_mcr_fops, mcr_get, mcr_set , "%llx\n");
 
 static struct dentry *iosf_dbg;
+
 static void iosf_sideband_debug_init(void)
 {
 	struct dentry *d;
@@ -257,7 +258,20 @@ static void iosf_sideband_debug_init(void)
 cleanup:
 	debugfs_remove_recursive(d);
 }
-/********************** debugfs end ****************************/
+
+static void iosf_debugfs_init(void)
+{
+	iosf_sideband_debug_init();
+}
+
+static void iosf_debugfs_remove(void)
+{
+	debugfs_remove_recursive(iosf_dbg);
+}
+#else
+static inline void iosf_debugfs_init(void) { }
+static inline void iosf_debugfs_remove(void) { }
+#endif /* CONFIG_IOSF_MBI_DEBUG */
 
 static int iosf_mbi_probe(struct pci_dev *pdev,
 			  const struct pci_device_id *unused)
@@ -290,13 +304,14 @@ static struct pci_driver iosf_mbi_pci_driver = {
 
 static int __init iosf_mbi_init(void)
 {
-	iosf_sideband_debug_init();
+	iosf_debugfs_init();
+
 	return pci_register_driver(&iosf_mbi_pci_driver);
 }
 
 static void __exit iosf_mbi_exit(void)
 {
-	debugfs_remove_recursive(iosf_dbg);
+	iosf_debugfs_remove();
 
 	pci_unregister_driver(&iosf_mbi_pci_driver);
 	if (mbi_pdev) {
-- 
1.9.1