[Xen-devel] [PATCHv2 2/5] xen/arm: add 8250 compatible UART support for early_printk

[Chen Baozi <baozich@xxxxxxxxx>]

Both OMAP5 and sun6i SoCs share this UART driver for early_printk.

Signed-off-by: Chen Baozi <baozich@xxxxxxxxx>
---
 docs/misc/arm/early-printk.txt    |  2 ++
 xen/arch/arm/Rules.mk             |  8 ++++++++
 xen/arch/arm/arm32/debug-8250.inc | 41 +++++++++++++++++++++++++++++++++++++++
 xen/include/xen/8250-uart.h       |  4 ++++
 4 files changed, 55 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..f24c6c0 100644
--- a/docs/misc/arm/early-printk.txt
+++ b/docs/misc/arm/early-printk.txt
@@ -13,6 +13,8 @@ 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
+  - omap5432: printk with UART3 on TI OMAP5432 processors
+  - 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 a18e7fd..7f11e5c 100644
--- a/xen/arch/arm/Rules.mk
+++ b/xen/arch/arm/Rules.mk
@@ -64,6 +64,14 @@ EARLY_PRINTK_INC := pl011
 EARLY_PRINTK_BAUD := 115200
 EARLY_UART_BASE_ADDRESS := 0xfff36000
 endif
+ifeq ($(CONFIG_EARLY_PRINTK), omap5432)
+EARLY_PRINTK_INC := 8250
+EARLY_UART_BASE_ADDRESS := 0x48020000
+endif
+ifeq ($(CONFIG_EARLY_PRINTK), sun6i)
+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..c0f4803
--- /dev/null
+++ b/xen/arch/arm/arm32/debug-8250.inc
@@ -0,0 +1,41 @@
+/*
+ * xen/arch/arm/arm32/debug-8250.inc
+ *
+ * 8250 specific debug code
+ *
+ * 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.
+ */
+
+#include <xen/8250-uart.h>
+
+/* 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 << REG_SHIFT)] /* Read LSR */
+       tst     \rc, #UART_LSR_THRE   /* Check Xmit holding register flag */
+       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_THR]      /* Write Transmit buffer */
+.endm
+
+/*
+ * Local variables:
+ * mode: ASM
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/include/xen/8250-uart.h b/xen/include/xen/8250-uart.h
index 7287364..33daa6d 100644
--- a/xen/include/xen/8250-uart.h
+++ b/xen/include/xen/8250-uart.h
@@ -22,6 +22,10 @@
 #ifndef __XEN_8250_UART_H__
 #define __XEN_8250_UART_H__
 
+#ifdef CONFIG_ARM
+#define REG_SHIFT         2
+#endif
+
 /* Register offsets */
 #define UART_RBR          0x00    /* receive buffer       */
 #define UART_THR          0x00    /* transmit holding     */
-- 
1.8.1.4


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