bus: mvebu-mbus: Avoid setting an undefined window size

The mbus hardware requires a power of two size, and size aligned base.
Currently, if a non-power of two is passed in to the low level routines
they configure the register in a way that results in undefined behaviour.

Call WARN and return EINVAL instead.

Also, update the debugfs routines to show a message if there is an
invalid register setting.

All together this makes the recent problems with silent failure
of PCI very obvious, noisy and debuggable.

Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397823593-1932-6-git-send-email-thomas.petazzoni@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

1 files changed, 16 insertions, 0 deletions

diff --git a/drivers/bus/mvebu-mbus.c b/drivers/bus/mvebu-mbus.c
index 293e2e0a0a87..afee0f731111 100644
--- a/drivers/bus/mvebu-mbus.c
+++ b/drivers/bus/mvebu-mbus.c
@@ -56,6 +56,7 @@
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/debugfs.h>
+#include <linux/log2.h>
 
 /*
  * DDR target is the same on all platforms.
@@ -266,6 +267,17 @@ static int mvebu_mbus_setup_window(struct mvebu_mbus_state *mbus,
                 mbus->soc->win_cfg_offset(win);
         u32 ctrl, remap_addr;
 
+        if (!is_power_of_2(size)) {
+                WARN(true, "Invalid MBus window size: 0x%zx\n", size);
+                return -EINVAL;
+        }
+
+        if ((base & (phys_addr_t)(size - 1)) != 0) {
+                WARN(true, "Invalid MBus base/size: %pa len 0x%zx\n", &base,
+                     size);
+                return -EINVAL;
+        }
+
         ctrl = ((size - 1) & WIN_CTRL_SIZE_MASK) |
                 (attr << WIN_CTRL_ATTR_SHIFT)    |
                 (target << WIN_CTRL_TGT_SHIFT)   |
@@ -413,6 +425,10 @@ static int mvebu_devs_debug_show(struct seq_file *seq, void *v)
                            win, (unsigned long long)wbase,
                            (unsigned long long)(wbase + wsize), wtarget, wattr);
 
+                if (!is_power_of_2(wsize) ||
+                    ((wbase & (u64)(wsize - 1)) != 0))
+                        seq_puts(seq, " (Invalid base/size!!)");
+
                 if (win < mbus->soc->num_remappable_wins) {
                         seq_printf(seq, " (remap %016llx)\n",
                                    (unsigned long long)wremap);