ARM: 7850/1: DEBUG_LL on efm32 SoCs

This implements output of debug messages on efm32 SoCs.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/Kconfig.debug

@@ -834,6 +834,20 @@ choice
 		  options; the platform specific options are deprecated
 		  and will be soon removed.
 
+	config DEBUG_LL_UART_EFM32
+		bool "Kernel low-level debugging via efm32 UART"
+		depends on ARCH_EFM32
+		help
+		  Say Y here if you want the debug print routines to direct
+		  their output to an UART or USART port on efm32 based
+		  machines. Use the following addresses for DEBUG_UART_PHYS:
+
+		    0x4000c000 | USART0
+		    0x4000c400 | USART1
+		    0x4000c800 | USART2
+		    0x4000e000 | UART0
+		    0x4000e400 | UART1
+
 	config DEBUG_LL_UART_PL01X
 		bool "Kernel low-level debugging via ARM Ltd PL01x Primecell UART"
 		help
@@ -885,6 +899,7 @@ config DEBUG_LL_INCLUDE
 	default "debug/8250.S" if DEBUG_LL_UART_8250 || DEBUG_UART_8250
 	default "debug/pl01x.S" if DEBUG_LL_UART_PL01X || DEBUG_UART_PL01X
 	default "debug/exynos.S" if DEBUG_EXYNOS_UART
+	default "debug/efm32.S" if DEBUG_LL_UART_EFM32
 	default "debug/icedcc.S" if DEBUG_ICEDCC
 	default "debug/imx.S" if DEBUG_IMX1_UART || \
 				 DEBUG_IMX25_UART || \
@@ -951,6 +966,7 @@ config DEBUG_UART_PHYS
 	default 0x20064000 if DEBUG_RK29_UART1 || DEBUG_RK3X_UART2
 	default 0x20068000 if DEBUG_RK29_UART2 || DEBUG_RK3X_UART3
 	default 0x20201000 if DEBUG_BCM2835
+	default 0x4000e400 if DEBUG_LL_UART_EFM32
 	default 0x40090000 if ARCH_LPC32XX
 	default 0x40100000 if DEBUG_PXA_UART1
 	default 0x42000000 if ARCH_GEMINI
@@ -981,6 +997,7 @@ config DEBUG_UART_PHYS
 	default 0xfff36000 if DEBUG_HIGHBANK_UART
 	default 0xfffff700 if ARCH_IOP33X
 	depends on DEBUG_LL_UART_8250 || DEBUG_LL_UART_PL01X || \
+		DEBUG_LL_UART_EFM32 || \
 		DEBUG_UART_8250 || DEBUG_UART_PL01X
 
 config DEBUG_UART_VIRT

arch/arm/include/debug/efm32.S

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2013 Pengutronix
+ * Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#define UARTn_CMD		0x000c
+#define UARTn_CMD_TXEN			0x0004
+
+#define	UARTn_STATUS		0x0010
+#define	UARTn_STATUS_TXC		0x0020
+#define	UARTn_STATUS_TXBL		0x0040
+
+#define	UARTn_TXDATA		0x0034
+
+		.macro	addruart, rx, tmp
+		ldr	\rx, =(CONFIG_DEBUG_UART_PHYS)
+
+		/*
+		 * enable TX. The driver might disable it to save energy. We
+		 * don't care about disabling at the end as during debug power
+		 * consumption isn't that important.
+		 */
+		ldr	\tmp, =(UARTn_CMD_TXEN)
+		str	\tmp, [\rx, #UARTn_CMD]
+		.endm
+
+		.macro	senduart,rd,rx
+		strb	\rd, [\rx, #UARTn_TXDATA]
+		.endm
+
+		.macro	waituart,rd,rx
+1001:		ldr	\rd, [\rx, #UARTn_STATUS]
+		tst	\rd, #UARTn_STATUS_TXBL
+		beq	1001b
+		.endm
+
+		.macro	busyuart,rd,rx
+1001:		ldr	\rd, [\rx, UARTn_STATUS]
+		tst	\rd, #UARTn_STATUS_TXC
+		bne	1001b
+		.endm