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| author | Andre Przywara <andre.przywara@calxeda.com> | 2013-05-24 15:47:27 +0200 |
|---|---|---|
| committer | Ian Campbell <ian.campbell@citrix.com> | 2013-05-30 09:20:29 +0100 |
| commit | 130645eee340608c12b632535d3f983508348ba1 (patch) | |
| tree | 21797a241726ed079f4bdc8d06aac587ccef5138 | |
| parent | b68346247f74e002ef180403167888a03f488080 (diff) | |
| download | xen-130645eee340608c12b632535d3f983508348ba1.tar.gz xen-130645eee340608c12b632535d3f983508348ba1.tar.bz2 xen-130645eee340608c12b632535d3f983508348ba1.zip | |
arm/early-printk: allow skipping of UART init
While it seems obvious to initialize the UART before using it, chances
are that some firmware code or the bootloader already did this.
So it may actually be a good idea to skip the initialization, in fact
this fixes early printk on my TC2 Versatile Express.
So provide an option in xen/arch/arm/Rules.mk to only initialize the
UART when needed.
Signed-off-by: Andre Przywara <andre.przywara@calxeda.com>
Reviewed-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
| -rw-r--r-- | docs/misc/arm/early-printk.txt | 4 | ||||
| -rw-r--r-- | xen/arch/arm/Rules.mk | 2 | ||||
| -rw-r--r-- | xen/arch/arm/arm32/head.S | 2 | ||||
| -rw-r--r-- | xen/arch/arm/arm64/head.S | 2 |
4 files changed, 10 insertions, 0 deletions
diff --git a/docs/misc/arm/early-printk.txt b/docs/misc/arm/early-printk.txt index 10c30531f6..965add56b8 100644 --- a/docs/misc/arm/early-printk.txt +++ b/docs/misc/arm/early-printk.txt @@ -14,5 +14,9 @@ where mach is the name of the machine: The baud rate is hardcoded in xen/arch/arm/Rules.mk, see there when adding support for new machines. +If not explicitly requested with "EARLY_PRINTK_INIT_UART := y" in Rules.mk, +the code will not try to initialize the UART, so that bootloader or +firmware settings can be used for maximum compatibility. The baud rate +parameter is ignored in this case. By default early printk is disabled. diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk index b4d690716a..fdcf73e453 100644 --- a/xen/arch/arm/Rules.mk +++ b/xen/arch/arm/Rules.mk @@ -49,6 +49,7 @@ EARLY_PRINTK_BAUD := 38400 endif ifeq ($(CONFIG_EARLY_PRINTK), exynos5250) EARLY_PRINTK_INC := exynos4210 +EARLY_PRINTK_INIT_UART := y EARLY_PRINTK_BAUD := 115200 endif @@ -57,6 +58,7 @@ EARLY_PRINTK := y endif CFLAGS-$(EARLY_PRINTK) += -DEARLY_PRINTK +CFLAGS-$(EARLY_PRINTK_INIT_UART) += -DEARLY_PRINTK_INIT_UART CFLAGS-$(EARLY_PRINTK) += -DEARLY_PRINTK_INC=\"debug-$(EARLY_PRINTK_INC).inc\" CFLAGS-$(EARLY_PRINTK) += -DEARLY_PRINTK_BAUD=$(EARLY_PRINTK_BAUD) endif diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S index ec7f640613..0588d54709 100644 --- a/xen/arch/arm/arm32/head.S +++ b/xen/arch/arm/arm32/head.S @@ -369,7 +369,9 @@ fail: PRINT("- Boot failed -\r\n") * r11: Early UART base address * Clobbers r0-r2 */ init_uart: +#ifdef EARLY_PRINTK_INIT_UART early_uart_init r11, r1, r2 +#endif adr r0, 1f b puts /* Jump to puts */ 1: .asciz "- UART enabled -\r\n" diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S index 89559469ad..21b7e4d741 100644 --- a/xen/arch/arm/arm64/head.S +++ b/xen/arch/arm/arm64/head.S @@ -116,7 +116,9 @@ boot_cpu: #ifdef EARLY_PRINTK ldr x23, =EARLY_UART_BASE_ADDRESS /* x23 := UART base address */ cbnz x22, 1f +#ifdef EARLY_PRINTK_INIT_UART bl init_uart /* CPU 0 sets up the UART too */ +#endif 1: PRINT("- CPU ") mov x0, x22 bl putn |