OMAP: iommu: add initial debugfs support

This enables to peek the following data.

$ /debug/iommu/isp# ls
mem             nr_tlb_entries  regs
mmap            pagetable       tlb
$ /debug/iommu/isp# head pagetable
L:      da:      pa:
-----------------------------------------
2: 00001000 8ae4a002
2: 00002000 8e7bb002
2: 00003000 8ae49002
2: 00004000 8ae65002
.....

Signed-off-by: Hiroshi DOYU <Hiroshi.DOYU@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

1 files changed, 14 insertions, 5 deletions

diff --git a/arch/arm/mach-omap2/iommu2.c b/arch/arm/mach-omap2/iommu2.c
index 015f22a53ead..2d9b5cc981cd 100644
--- a/arch/arm/mach-omap2/iommu2.c
+++ b/arch/arm/mach-omap2/iommu2.c
@@ -217,10 +217,19 @@ static ssize_t omap2_dump_cr(struct iommu *obj, struct cr_regs *cr, char *buf)
 }
 
 #define pr_reg(name)                                                    \
-        p += sprintf(p, "%20s: %08x\n",                                 \
-                     __stringify(name), iommu_read_reg(obj, MMU_##name));
-
-static ssize_t omap2_iommu_dump_ctx(struct iommu *obj, char *buf)
+        do {                                                            \
+                ssize_t bytes;                                          \
+                const char *str = "%20s: %08x\n";                       \
+                const int maxcol = 32;                                  \
+                bytes = snprintf(p, maxcol, str, __stringify(name),     \
+                                 iommu_read_reg(obj, MMU_##name));      \
+                p += bytes;                                             \
+                len -= bytes;                                           \
+                if (len < maxcol)                                       \
+                        goto out;                                       \
+        } while (0)
+
+static ssize_t omap2_iommu_dump_ctx(struct iommu *obj, char *buf, ssize_t len)
 {
         char *p = buf;
 
@@ -242,7 +251,7 @@ static ssize_t omap2_iommu_dump_ctx(struct iommu *obj, char *buf)
         pr_reg(READ_CAM);
         pr_reg(READ_RAM);
         pr_reg(EMU_FAULT_AD);
-
+out:
         return p - buf;
 }