From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bamvor Jian Zhang Subject: [PATCH V2 2/2] xen: arm: implement early prink for 8250 uart Date: Tue, 2 Jul 2013 21:11:54 +0800 Message-ID: <1372770714-1657-3-git-send-email-bjzhang@suse.com> References: <1372770714-1657-1-git-send-email-bjzhang@suse.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1372770714-1657-1-git-send-email-bjzhang@suse.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: xen-devel@lists.xen.org Cc: andre.przywara@calxeda.com, ian.campbell@citrix.com, Stefano.Stabellini@eu.citrix.com, julien.grall@linaro.org, bjzhang@suse.com, baozich@gmail.com List-Id: xen-devel@lists.xenproject.org implement early printk for 8250 uart which is used by lots of arm SOC, such as Allwinner A31(sun6i) and OMAP5432. Signed-off-by: Bamvor Jian Zhang --- docs/misc/arm/early-printk.txt | 1 + xen/arch/arm/Rules.mk | 5 ++++ xen/arch/arm/arm32/debug-8250.inc | 48 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 54 insertions(+) create mode 100644 xen/arch/arm/arm32/debug-8250.inc diff --git a/docs/misc/arm/early-printk.txt b/docs/misc/arm/early-printk.txt index fbc3208..eaa66a1 100644 --- a/docs/misc/arm/early-printk.txt +++ b/docs/misc/arm/early-printk.txt @@ -13,6 +13,7 @@ where mach is the name of the machine: - exynos5250: printk with the second UART - midway: printk with the pl011 on Calxeda Midway processors - fastmodel: printk on ARM Fastmodel software emulators + - sun6i: printk with 8250 on Allwinner A31 processors The base address and baud rate is hardcoded in xen/arch/arm/Rules.mk, see there when adding support for new machines. diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk index 422ed04..51e823d 100644 --- a/xen/arch/arm/Rules.mk +++ b/xen/arch/arm/Rules.mk @@ -64,6 +64,11 @@ EARLY_PRINTK_INC := pl011 EARLY_PRINTK_BAUD := 115200 EARLY_UART_BASE_ADDRESS := 0xfff36000 endif +ifeq ($(CONFIG_EARLY_PRINTK), sun6i) +# uart configured at 115200 by bootloader +EARLY_PRINTK_INC := 8250 +EARLY_UART_BASE_ADDRESS := 0x01c28000 +endif ifneq ($(EARLY_PRINTK_INC),) EARLY_PRINTK := y diff --git a/xen/arch/arm/arm32/debug-8250.inc b/xen/arch/arm/arm32/debug-8250.inc new file mode 100644 index 0000000..c11357d --- /dev/null +++ b/xen/arch/arm/arm32/debug-8250.inc @@ -0,0 +1,48 @@ +/* + * xen/arch/arm/arm32/debug-8250.inc + * + * 8250 specific debug code + * + * Bamvor Jian Zhang + * Copyright (c) 2013 SUSE + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + + +#define UART_TX (0x00<<2) /* Out: Transmit buffer */ +#define UART_LSR (0x05<<2) /* In: Line Status Register */ + +#define UART_LSR_THRE 0x20 /* Xmit holding register empty */ + +/* 8250 UART wait UART to be ready to transmit + * rb: register which contains the UART base address + * rc: scratch register */ +.macro early_uart_ready rb, rc +1: + ldr \rc, [\rb, #UART_LSR] /* <- UART_LSR (Line Status Register) */ + tst \rc, #UART_LSR_THRE /* Check BUSY bit */ + beq 1b /* Wait for the UART to be ready */ +.endm + +/* 8250 UART transmit character + * rb: register which contains the UART base address + * rt: register which contains the character to transmit */ +.macro early_uart_transmit rb, rt + str \rt, [\rb, #UART_TX] /* -> UART_TX */ +.endm + +/* + * Local variables: + * mode: ASM + * indent-tabs-mode: nil + * End: + */ -- 1.8.1.4