ARM: sti: Add DEBUG_LL console support

This patch adds low level debug uart support to sti based SOCs.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@st.com>
CC: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Olof Johansson <olof@lixom.net>

arch/arm/include/debug/sti.S

@@ -0,0 +1,61 @@
+/*
+ * arch/arm/include/debug/sti.S
+ *
+ * Debugging macro include header
+ * Copyright (C) 2013 STMicroelectronics (R&D) Limited.
+ *
+ * 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 STIH41X_COMMS_BASE              0xfed00000
+#define STIH41X_ASC2_BASE               (STIH41X_COMMS_BASE+0x32000)
+
+#define STIH41X_SBC_LPM_BASE            0xfe400000
+#define STIH41X_SBC_COMMS_BASE          (STIH41X_SBC_LPM_BASE + 0x100000)
+#define STIH41X_SBC_ASC1_BASE           (STIH41X_SBC_COMMS_BASE + 0x31000)
+
+
+#define VIRT_ADDRESS(x)		(x - 0x1000000)
+
+#if IS_ENABLED(CONFIG_STIH41X_DEBUG_ASC2)
+#define DEBUG_LL_UART_BASE	STIH41X_ASC2_BASE
+#endif
+
+#if IS_ENABLED(CONFIG_STIH41X_DEBUG_SBC_ASC1)
+#define DEBUG_LL_UART_BASE	STIH41X_SBC_ASC1_BASE
+#endif
+
+#ifndef DEBUG_LL_UART_BASE
+#error "DEBUG UART is not Configured"
+#endif
+
+#define ASC_TX_BUF_OFF  0x04
+#define ASC_CTRL_OFF    0x0c
+#define ASC_STA_OFF     0x14
+
+#define ASC_STA_TX_FULL         (1<<9)
+#define ASC_STA_TX_EMPTY        (1<<1)
+
+
+		.macro	addruart, rp, rv, tmp
+		ldr	\rp,      =DEBUG_LL_UART_BASE	@ physical base
+		ldr	\rv,      =VIRT_ADDRESS(DEBUG_LL_UART_BASE) @ virt base
+		.endm
+
+                .macro  senduart,rd,rx
+                strb    \rd, [\rx, #ASC_TX_BUF_OFF]
+                .endm
+
+                .macro  waituart,rd,rx
+1001:           ldr     \rd, [\rx, #ASC_STA_OFF]
+                tst     \rd, #ASC_STA_TX_FULL
+                bne     1001b
+                .endm
+
+                .macro  busyuart,rd,rx
+1001:           ldr     \rd, [\rx, #ASC_STA_OFF]
+                tst     \rd, #ASC_STA_TX_EMPTY
+                beq     1001b
+                .endm