x86/iosf: Add debugfs support

Allows access to the iosf sideband through debugfs.

Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Link: http://lkml.kernel.org/r/1409175640-32426-3-git-send-email-david.e.box@linux.intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 74 insertions, 0 deletions

diff --git a/arch/x86/kernel/iosf_mbi.c b/arch/x86/kernel/iosf_mbi.c
index 9030e83db6ee..0a2faa3892cb 100644
--- a/arch/x86/kernel/iosf_mbi.c
+++ b/arch/x86/kernel/iosf_mbi.c
@@ -22,6 +22,8 @@
 #include <linux/init.h>
 #include <linux/spinlock.h>
 #include <linux/pci.h>
+#include <linux/debugfs.h>
+#include <linux/capability.h>
 
 #include <asm/iosf_mbi.h>
 
@@ -187,6 +189,75 @@ bool iosf_mbi_available(void)
 }
 EXPORT_SYMBOL(iosf_mbi_available);
 
+/********************** debugfs begin ****************************/
+static u32      dbg_mdr;
+static u32      dbg_mcr;
+static u32      dbg_mcrx;
+
+static int mcr_get(void *data, u64 *val)
+{
+        *val = *(u32 *)data;
+        return 0;
+}
+
+static int mcr_set(void *data, u64 val)
+{
+        u8 command = ((u32)val & 0xFF000000) >> 24,
+           port    = ((u32)val & 0x00FF0000) >> 16,
+           offset  = ((u32)val & 0x0000FF00) >> 8;
+        int err;
+
+        *(u32 *)data = val;
+
+        if (!capable(CAP_SYS_RAWIO))
+                return -EACCES;
+
+        if (command & 1u)
+                err = iosf_mbi_write(port,
+                               command,
+                               dbg_mcrx | offset,
+                               dbg_mdr);
+        else
+                err = iosf_mbi_read(port,
+                              command,
+                              dbg_mcrx | offset,
+                              &dbg_mdr);
+
+        return err;
+}
+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;
+
+        iosf_dbg = debugfs_create_dir("iosf_sb", NULL);
+        if (IS_ERR_OR_NULL(iosf_dbg))
+                return;
+
+        /* mdr */
+        d = debugfs_create_x32("mdr", 0660, iosf_dbg, &dbg_mdr);
+        if (IS_ERR_OR_NULL(d))
+                goto cleanup;
+
+        /* mcrx */
+        debugfs_create_x32("mcrx", 0660, iosf_dbg, &dbg_mcrx);
+        if (IS_ERR_OR_NULL(d))
+                goto cleanup;
+
+        /* mcr - initiates mailbox tranaction */
+        debugfs_create_file("mcr", 0660, iosf_dbg, &dbg_mcr, &iosf_mcr_fops);
+        if (IS_ERR_OR_NULL(d))
+                goto cleanup;
+
+        return;
+
+cleanup:
+        debugfs_remove_recursive(d);
+}
+/********************** debugfs end ****************************/
+
 static int iosf_mbi_probe(struct pci_dev *pdev,
                           const struct pci_device_id *unused)
 {
@@ -217,11 +288,14 @@ static struct pci_driver iosf_mbi_pci_driver = {
 
 static int __init iosf_mbi_init(void)
 {
+        iosf_sideband_debug_init();
         return pci_register_driver(&iosf_mbi_pci_driver);
 }
 
 static void __exit iosf_mbi_exit(void)
 {
+        debugfs_remove_recursive(iosf_dbg);
+
         pci_unregister_driver(&iosf_mbi_pci_driver);
         if (mbi_pdev) {
                 pci_dev_put(mbi_pdev);