linux-ls1: fix reset issue

Watchdog failed to assert reset signal so the board hanged everytime
a reboot command was issued. The watchdog (same controller used for
i.MX platforms) has an errata mentioning a software workaround for
a hardware issue that has no scheduled fix.

Implemented the workaround described in the errata. The workaround is
already present in upstream repositories.

Signed-off-by: Stefan Sicleru <stefan.sicleru@enea.com>
Signed-off-by: Martin Borg <martin.borg@enea.com>

2 files changed, 36 insertions, 0 deletions

diff --git a/recipes-kernel/linux/linux-ls1/0002-watchdog-fix-errata-err004346.patch b/recipes-kernel/linux/linux-ls1/0002-watchdog-fix-errata-err004346.patch
new file mode 100644
index 0000000..a69ef9b
--- /dev/null
+++ b/recipes-kernel/linux/linux-ls1/0002-watchdog-fix-errata-err004346.patch
@@ -0,0 +1,35 @@
+From ff7712de39c333cf888e497a90f88601ef3e228f Mon Sep 17 00:00:00 2001
+From: Stefan Sicleru <stefan.sicleru@enea.com>
+Date: Fri, 10 Jun 2016 10:42:28 +0200
+Subject: [PATCH] watchdog: fix errata ERR004346
+
+Due to errata ERR004346 (WDOG: SRS bit requires to be written twice), two
+additional writes are added to ensure that at least two writes occur within
+one period of the 32kHz clock.
+
+Replace __raw_writew() calls with *_relaxed() calls in order to be
+endian-safe.
+
+Signed-off-by: Stefan Sicleru <stefan.sicleru@enea.com>
+---
+ arch/arm/mach-imx/system.c | 5 ++++-
+ 1 file changed, 4 insertions(+), 1 deletion(-)
+
+diff --git a/arch/arm/mach-imx/system.c b/arch/arm/mach-imx/system.c
+index 80c177c..6e09ac0 100644
+--- a/arch/arm/mach-imx/system.c
++++ b/arch/arm/mach-imx/system.c
+@@ -51,7 +51,10 @@ void mxc_restart(enum reboot_mode mode, const char *cmd)
+                wcr_enable = (1 << 2);
+
+        /* Assert SRS signal */
+-       __raw_writew(wcr_enable, wdog_base);
++
++       writew_relaxed(wcr_enable, wdog_base);
++       writew_relaxed(wcr_enable, wdog_base);
++       writew_relaxed(wcr_enable, wdog_base);
+
+        /* wait for reset to assert... */
+        mdelay(500);
+--
+1.9.1
diff --git a/recipes-kernel/linux/linux-ls1_3.12.bbappend b/recipes-kernel/linux/linux-ls1_3.12.bbappend
index e8fd2e4..e0c7a91 100644
--- a/recipes-kernel/linux/linux-ls1_3.12.bbappend
+++ b/recipes-kernel/linux/linux-ls1_3.12.bbappend
@@ -4,6 +4,7 @@ FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
 
 SRC_URI += "file://ls1021aiot.dts \
             file://0001-fsnotify-fix-oops-in-fsnotify_clear_marks_by_group_f.patch \
+            file://0002-watchdog-fix-errata-err004346.patch \
            "
 
 # fix err: "linux-ls1-3.12-r0 do_deploy: Taskhash mismatch"