ARM: tegra: decouple uncompress.h and debug-macro.S

Prior to this change, Tegra's debug-macro.S relied on uncompress.h having
determined which UART to use, and whether it was safe to use the UART
(i.e. is it not in reset, and is clocked). This determination was
communicated from uncompress.h to debug-macro.S using a few bytes of
Tegra's IRAM (an on-SoC RAM). This had the disadvantage that uncompress.h
was a required part of the kernel boot process; booting a non-compressed
kernel would not allow earlyprintk to operate.

This change duplicates the UART selection and validation logic into
debug-macro.S so that the reliance on uncompress.h is removed.

This also helps out with single-zImage work, since there is currently no
support for using any uncompress.h with single-zImage.
Signed-off-by: Stephen Warren <swarren@nvidia.com>

arch/arm/mach-tegra/common.c

@@ -44,13 +44,15 @@
  * kernel is loaded. The data is declared here rather than debug-macro.S so
  * that multiple inclusions of debug-macro.S point at the same data.
  */
-u32 tegra_uart_config[3] = {
+u32 tegra_uart_config[4] = {
 	/* Debug UART initialization required */
 	1,
 	/* Debug UART physical address */
 	0,
 	/* Debug UART virtual address */
 	0,
+	/* Scratch space for debug macro */
+	0,
 };
 
 #ifdef CONFIG_OF

arch/arm/mach-tegra/include/mach/debug-macro.S

@@ -27,7 +27,42 @@
 #include <linux/serial_reg.h>
 
 #include "../../iomap.h"
-#include "../../irammap.h"
+
+#define UART_SHIFT 2
+
+#define TEGRA_CLK_RST_DEVICES_L		(TEGRA_CLK_RESET_BASE + 0x04)
+#define TEGRA_CLK_RST_DEVICES_H		(TEGRA_CLK_RESET_BASE + 0x08)
+#define TEGRA_CLK_RST_DEVICES_U		(TEGRA_CLK_RESET_BASE + 0x0c)
+#define TEGRA_CLK_OUT_ENB_L		(TEGRA_CLK_RESET_BASE + 0x10)
+#define TEGRA_CLK_OUT_ENB_H		(TEGRA_CLK_RESET_BASE + 0x14)
+#define TEGRA_CLK_OUT_ENB_U		(TEGRA_CLK_RESET_BASE + 0x18)
+#define TEGRA_PMC_SCRATCH20		(TEGRA_PMC_BASE + 0xa0)
+#define TEGRA_APB_MISC_GP_HIDREV	(TEGRA_APB_MISC_BASE + 0x804)
+
+#define checkuart(rp, rv, lhu, bit, uart) \
+		/* Load address of CLK_RST register */ \
+		movw	rp, #TEGRA_CLK_RST_DEVICES_##lhu & 0xffff ; \
+		movt	rp, #TEGRA_CLK_RST_DEVICES_##lhu >> 16 ; \
+		/* Load value from CLK_RST register */ \
+		ldr	rp, [rp, #0] ; \
+		/* Test UART's reset bit */ \
+		tst	rp, #(1 << bit) ; \
+		/* If set, can't use UART; jump to save no UART */ \
+		bne	90f ; \
+		/* Load address of CLK_OUT_ENB register */ \
+		movw	rp, #TEGRA_CLK_OUT_ENB_##lhu & 0xffff ; \
+		movt	rp, #TEGRA_CLK_OUT_ENB_##lhu >> 16 ; \
+		/* Load value from CLK_OUT_ENB register */ \
+		ldr	rp, [rp, #0] ; \
+		/* Test UART's clock enable bit */ \
+		tst	rp, #(1 << bit) ; \
+		/* If clear, can't use UART; jump to save no UART */ \
+		beq	90f ; \
+		/* Passed all tests, load address of UART registers */ \
+		movw	rp, #TEGRA_UART##uart##_BASE & 0xffff ; \
+		movt	rp, #TEGRA_UART##uart##_BASE >> 16 ; \
+		/* Jump to save UART address */ \
+		b 91f
 
 		.macro  addruart, rp, rv, tmp
 		adr	\rp, 99f		@ actual addr of 99f
@@ -36,22 +71,101 @@
 		ldr	\rp, [\rp, #4]		@ linked tegra_uart_config
 		sub	\tmp, \rp, \rv		@ actual tegra_uart_config
 		ldr	\rp, [\tmp]		@ Load tegra_uart_config
-		cmp	\rp, #1			@ needs intitialization?
+		cmp	\rp, #1			@ needs initialization?
 		bne	100f			@ no; go load the addresses
 		mov	\rv, #0			@ yes; record init is done
 		str	\rv, [\tmp]
-		mov	\rp, #TEGRA_IRAM_BASE	@ See if cookie is in IRAM
-		ldr	\rv, [\rp, #TEGRA_IRAM_DEBUG_UART_OFFSET]
-		movw	\rp, #TEGRA_IRAM_DEBUG_UART_COOKIE & 0xffff
-		movt	\rp, #TEGRA_IRAM_DEBUG_UART_COOKIE >> 16
-		cmp	\rv, \rp		@ Cookie present?
-		bne	100f			@ No, use default UART
-		mov	\rp, #TEGRA_IRAM_BASE	@ Load UART address from IRAM
-		ldr	\rv, [\rp, #TEGRA_IRAM_DEBUG_UART_OFFSET + 4]
-		str	\rv, [\tmp, #4]		@ Store in tegra_uart_phys
-		sub	\rv, \rv, #IO_APB_PHYS	@ Calculate virt address
+
+#ifdef CONFIG_TEGRA_DEBUG_UART_AUTO_ODMDATA
+		/* Check ODMDATA */
+10:		movw	\rp, #TEGRA_PMC_SCRATCH20 & 0xffff
+		movt	\rp, #TEGRA_PMC_SCRATCH20 >> 16
+		ldr	\rp, [\rp, #0]		@ Load PMC_SCRATCH20
+		ubfx	\rv, \rp, #18, #2	@ 19:18 are console type
+		cmp	\rv, #2			@ 2 and 3 mean DCC, UART
+		beq	11f			@ some boards swap the meaning
+		cmp	\rv, #3			@ so accept either
+		bne	90f
+11:		ubfx	\rv, \rp, #15, #3	@ 17:15 are UART ID
+		cmp	\rv, #0			@ UART 0?
+		beq	20f
+		cmp	\rv, #1			@ UART 1?
+		beq	21f
+		cmp	\rv, #2			@ UART 2?
+		beq	22f
+		cmp	\rv, #3			@ UART 3?
+		beq	23f
+		cmp	\rv, #4			@ UART 4?
+		beq	24f
+		b	90f			@ invalid
+#endif
+
+#if defined(CONFIG_TEGRA_DEBUG_UARTA) || \
+    defined(CONFIG_TEGRA_DEBUG_UART_AUTO_ODMDATA)
+		/* Check UART A validity */
+20:		checkuart(\rp, \rv, L, 6, A)
+#endif
+
+#if defined(CONFIG_TEGRA_DEBUG_UARTB) || \
+    defined(CONFIG_TEGRA_DEBUG_UART_AUTO_ODMDATA)
+		/* Check UART B validity */
+21:		checkuart(\rp, \rv, L, 7, B)
+#endif
+
+#if defined(CONFIG_TEGRA_DEBUG_UARTC) || \
+    defined(CONFIG_TEGRA_DEBUG_UART_AUTO_ODMDATA)
+		/* Check UART C validity */
+22:		checkuart(\rp, \rv, H, 23, C)
+#endif
+
+#if defined(CONFIG_TEGRA_DEBUG_UARTD) || \
+    defined(CONFIG_TEGRA_DEBUG_UART_AUTO_ODMDATA)
+		/* Check UART D validity */
+23:		checkuart(\rp, \rv, U, 1, D)
+#endif
+
+#if defined(CONFIG_TEGRA_DEBUG_UARTE) || \
+    defined(CONFIG_TEGRA_DEBUG_UART_AUTO_ODMDATA)
+		/* Check UART E validity */
+24:
+		checkuart(\rp, \rv, U, 2, E)
+#endif
+
+		/* No valid UART found */
+90:		mov	\rp, #0
+		/* fall through */
+
+		/* Record whichever UART we chose */
+91:		str	\rp, [\tmp, #4]		@ Store in tegra_uart_phys
+		cmp	\rp, #0			@ Valid UART address?
+		bne	92f			@ Yes, go process it
+		str	\rp, [\tmp, #8]		@ Store 0 in tegra_uart_phys
+		b	100f			@ Done
+92:		sub	\rv, \rp, #IO_APB_PHYS	@ Calculate virt address
 		add	\rv, \rv, #IO_APB_VIRT
 		str	\rv, [\tmp, #8]		@ Store in tegra_uart_virt
+		movw	\rv, #TEGRA_APB_MISC_GP_HIDREV & 0xffff
+		movt	\rv, #TEGRA_APB_MISC_GP_HIDREV >> 16
+		ldr	\rv, [\rv, #0]		@ Load HIDREV
+		ubfx	\rv, \rv, #8, #8	@ 15:8 are SoC version
+		cmp	\rv, #0x20		@ Tegra20?
+		moveq	\rv, #0x75		@ Tegra20 divisor
+		movne	\rv, #0xdd		@ Tegra30 divisor
+		str	\rv, [\tmp, #12]	@ Save divisor to scratch
+		/* uart[UART_LCR] = UART_LCR_WLEN8 | UART_LCR_DLAB; */
+		mov	\rv, #UART_LCR_WLEN8 | UART_LCR_DLAB
+		str	\rv, [\rp, #UART_LCR << UART_SHIFT]
+		/* uart[UART_DLL] = div & 0xff; */
+		ldr	\rv, [\tmp, #12]
+		and	\rv, \rv, #0xff
+		str	\rv, [\rp, #UART_DLL << UART_SHIFT]
+		/* uart[UART_DLM] = div >> 8; */
+		ldr	\rv, [\tmp, #12]
+		lsr	\rv, \rv, #8
+		str	\rv, [\rp, #UART_DLM << UART_SHIFT]
+		/* uart[UART_LCR] = UART_LCR_WLEN8; */
+		mov	\rv, #UART_LCR_WLEN8
+		str	\rv, [\rp, #UART_LCR << UART_SHIFT]
 		b	100f
 
 		.align
@@ -59,27 +173,24 @@
 		.word	tegra_uart_config
 		.ltorg
 
+		/* Load previously selected UART address */
 100:		ldr	\rp, [\tmp, #4]		@ Load tegra_uart_phys
 		ldr	\rv, [\tmp, #8]		@ Load tegra_uart_virt
 		.endm
 
-#define UART_SHIFT 2
-
 /*
  * Code below is swiped from <asm/hardware/debug-8250.S>, but add an extra
- * check to make sure that we aren't in the CONFIG_TEGRA_DEBUG_UART_NONE case.
- * We use the fact that all 5 valid UART addresses all have something in the
- * 2nd-to-lowest byte.
+ * check to make sure that the UART address is actually valid.
  */
 
 		.macro	senduart, rd, rx
-		tst	\rx, #0x0000ff00
+		cmp	\rx, #0
 		strneb	\rd, [\rx, #UART_TX << UART_SHIFT]
 1001:
 		.endm
 
 		.macro	busyuart, rd, rx
-		tst	\rx, #0x0000ff00
+		cmp	\rx, #0
 		beq	1002f
 1001:		ldrb	\rd, [\rx, #UART_LSR << UART_SHIFT]
 		and	\rd, \rd, #UART_LSR_TEMT | UART_LSR_THRE
@@ -90,7 +201,7 @@
 
 		.macro	waituart, rd, rx
 #ifdef FLOW_CONTROL
-		tst	\rx, #0x0000ff00
+		cmp	\rx, #0
 		beq	1002f
 1001:		ldrb	\rd, [\rx, #UART_MSR << UART_SHIFT]
 		tst	\rd, #UART_MSR_CTS

arch/arm/mach-tegra/include/mach/uncompress.h

@@ -29,7 +29,6 @@
 #include <linux/serial_reg.h>
 
 #include "../../iomap.h"
-#include "../../irammap.h"
 
 #define BIT(x) (1 << (x))
 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
@@ -52,17 +51,6 @@ static inline void flush(void)
 {
 }
 
-static inline void save_uart_address(void)
-{
-	u32 *buf = (u32 *)(TEGRA_IRAM_BASE + TEGRA_IRAM_DEBUG_UART_OFFSET);
-
-	if (uart) {
-		buf[0] = TEGRA_IRAM_DEBUG_UART_COOKIE;
-		buf[1] = (u32)uart;
-	} else
-		buf[0] = 0;
-}
-
 static const struct {
 	u32 base;
 	u32 reset_reg;
@@ -169,7 +157,6 @@ static inline void arch_decomp_setup(void)
 	else
 		uart = (volatile u8 *)uarts[uart_id].base;
 
-	save_uart_address();
 	if (uart == NULL)
 		return;
 

arch/arm/mach-tegra/irammap.h

@@ -23,13 +23,4 @@
 #define TEGRA_IRAM_RESET_HANDLER_OFFSET	0
 #define TEGRA_IRAM_RESET_HANDLER_SIZE	SZ_1K
 
-/*
- * These locations are written to by uncompress.h, and read by debug-macro.S.
- * The first word holds the cookie value if the data is valid. The second
- * word holds the UART physical address.
- */
-#define TEGRA_IRAM_DEBUG_UART_OFFSET	SZ_1K
-#define TEGRA_IRAM_DEBUG_UART_SIZE	8
-#define TEGRA_IRAM_DEBUG_UART_COOKIE	0x55415254
-
 #endif