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>

4 files changed, 134 insertions, 43 deletions

diff --git a/arch/arm/mach-tegra/common.c b/arch/arm/mach-tegra/common.c
index 8b41e4c0d53f..bce8591cb72b 100644
--- a/arch/arm/mach-tegra/common.c
+++ b/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
diff --git a/arch/arm/mach-tegra/include/mach/debug-macro.S b/arch/arm/mach-tegra/include/mach/debug-macro.S
index 44ca7b1d8b8a..d4c23d60d448 100644
--- a/arch/arm/mach-tegra/include/mach/debug-macro.S
+++ b/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
diff --git a/arch/arm/mach-tegra/include/mach/uncompress.h b/arch/arm/mach-tegra/include/mach/uncompress.h
index 4150c71c006f..485003f9b636 100644
--- a/arch/arm/mach-tegra/include/mach/uncompress.h
+++ b/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;
 
diff --git a/arch/arm/mach-tegra/irammap.h b/arch/arm/mach-tegra/irammap.h
index 0cbe63261854..501952a84344 100644
--- a/arch/arm/mach-tegra/irammap.h
+++ b/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