Running a qemu emulated cubieboard with sun4i-ss driver enabled led to a never
ending boot.
This is due to sun4i-ss deadlocked and taking all cpu in an infinite loop.
Since the crypto hardware is not implemented, all registers are read as 0.
So sun4i-ss will never progress in any operations. (TX_CNT being always 0)
The first idea is to add a "TX_CNT always zero timeout" but this made cipher/hash loops
more complex and prevent a case that never happen on real hardware.
The best way to fix is to check at probe time if we run on a virtual
machine with hardware emulated but non-implemented and prevent
sun4i-ss to be loaded in that case.
Letting sun4i-ss to load is useless anyway since all crypto algorithm will be
disabled since they will fail crypto selftests.
Tested-on: qemu-cubieboard
Tested-on: cubieboard2
Signed-off-by: Corentin Labbe <clabbe.montjoie@xxxxxxxxx>
---
drivers/crypto/sunxi-ss/sun4i-ss-core.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/drivers/crypto/sunxi-ss/sun4i-ss-core.c b/drivers/crypto/sunxi-ss/sun4i-ss-core.c
index a81d89b3b7d8..a178e80adcf3 100644
--- a/drivers/crypto/sunxi-ss/sun4i-ss-core.c
+++ b/drivers/crypto/sunxi-ss/sun4i-ss-core.c
@@ -341,9 +341,18 @@ static int sun4i_ss_probe(struct platform_device *pdev)
* I expect to be a sort of Security System Revision number.
* Since the A80 seems to have an other version of SS
* this info could be useful
+ * Detect virtual machine with non-implemented hardware
+ * (qemu-cubieboard) by checking the register value after a write to it.
+ * On non-implemented hardware, all registers are read as 0.
+ * On real hardware we should have a value > 0.
*/
writel(SS_ENABLED, ss->base + SS_CTL);
v = readl(ss->base + SS_CTL);
+ if (!v) {
+ dev_err(&pdev->dev, "Qemu with non-implemented SS detected.\n");
+ err = -ENODEV;
+ goto error_rst;
+ }
v >>= 16;
v &= 0x07;
dev_info(&pdev->dev, "Die ID %d\n", v);
@@ -398,6 +407,7 @@ static int sun4i_ss_probe(struct platform_device *pdev)
break;
}
}
+error_rst:
if (ss->reset)
reset_control_assert(ss->reset);
error_clk:
--
2.16.4
