[PATCH 1/5] bsp/atsam: Add option to disable 32kHz XTAL.

[Christian Mauderer]

From: Christian Mauderer <Christian.Mauderer at embedded-brains.de>

---
 c/src/lib/libbsp/arm/atsam/README                                 | 4 ++++
 c/src/lib/libbsp/arm/atsam/configure.ac                           | 8 ++++++++
 .../arm/atsam/libraries/libboard/resources_v71/system_samv71.c    | 2 ++
 3 files changed, 14 insertions(+)

diff --git a/c/src/lib/libbsp/arm/atsam/README b/c/src/lib/libbsp/arm/atsam/README
index c374e861c3..2ebaa726c8 100644
--- a/c/src/lib/libbsp/arm/atsam/README
+++ b/c/src/lib/libbsp/arm/atsam/README
@@ -43,6 +43,10 @@ const struct BOARD_Sdram_Config BOARD_Sdram_Config = {
 };
 --------
 
+Use ATSAM_SLOWCLOCK_USE_XTAL=0 to disable the usage of the external 32kHz
+oscillator for the slow clock. This is useful for example for the SAM E70
+Xplained kit.
+
 Use ATSAM_CONSOLE_BAUD=XYZ to set the initial baud for console devices (default
 115200).
 
diff --git a/c/src/lib/libbsp/arm/atsam/configure.ac b/c/src/lib/libbsp/arm/atsam/configure.ac
index 519d5237f6..3ebeb93255 100644
--- a/c/src/lib/libbsp/arm/atsam/configure.ac
+++ b/c/src/lib/libbsp/arm/atsam/configure.ac
@@ -72,6 +72,14 @@ RTEMS_BSPOPTS_HELP([ATSAM_MCK],
 [Frequency of the MCK in Hz. Set to 0 to force application defined speed.
 See startup/pmc-config.c for available clock configurations.])
 
+RTEMS_BSPOPTS_SET([ATSAM_SLOWCLOCK_USE_XTAL],[*],[1])
+RTEMS_BSPOPTS_HELP([ATSAM_SLOWCLOCK_USE_XTAL],
+[Use the external crystal as source for the slow clock instead of the internal
+RC oscillator. Note that on the ATSAM the NRST pin seems to depend on the slow
+clock as well as all watchdogs. If ATSAM_SLOWCLOCK_USE_XTAL is set to 1 without
+a external crystal connected, the controller might hang in the switching process
+without a working NRST pin. ])
+
 RTEMS_BSPOPTS_SET([ATSAM_CHANGE_CLOCK_FROM_SRAM],[*],[0])
 RTEMS_BSPOPTS_HELP([ATSAM_CHANGE_CLOCK_FROM_SRAM],
 [Move the functions that set up the clock into the SRAM.
diff --git a/c/src/lib/libbsp/arm/atsam/libraries/libboard/resources_v71/system_samv71.c b/c/src/lib/libbsp/arm/atsam/libraries/libboard/resources_v71/system_samv71.c
index 8d7eb8e6a7..19c5a947b5 100644
--- a/c/src/lib/libbsp/arm/atsam/libraries/libboard/resources_v71/system_samv71.c
+++ b/c/src/lib/libbsp/arm/atsam/libraries/libboard/resources_v71/system_samv71.c
@@ -93,6 +93,7 @@ extern "C" {
 	 * OSC
 	 */
 
+#if ATSAM_SLOWCLOCK_USE_XTAL == 1
 	read_MOR = PMC->CKGR_MOR;
 	/* enable external crystal - enable RC OSC */
 	read_MOR |= (CKGR_MOR_KEY_PASSWD | CKGR_MOR_XT32KFME);
@@ -104,6 +105,7 @@ extern "C" {
 
 		while (!(SUPC->SUPC_SR & SUPC_SR_OSCSEL));
 	}
+#endif
 
 	/* Initialize main oscillator */
 	if (!(PMC->CKGR_MOR & CKGR_MOR_MOSCSEL)) {
-- 
2.13.6