[POWERPC] Early serial debug support for PPC44x
This adds support for early serial debugging via the built in
port on IBM/AMCC PowerPC 44x CPUs. It uses a bolted TLB entry in
address space 1 for the UART's mapping, allowing robust debugging both
before and after the initialization of the MMU.
Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index 86aa374..f70e795 100644
--- a/arch/powerpc/Kconfig.debug
+++ b/arch/powerpc/Kconfig.debug
@@ -139,10 +139,6 @@
Say Y here to see progress messages from the boot firmware in text
mode. Requires either BootX or Open Firmware.
-config SERIAL_TEXT_DEBUG
- bool "Support for early boot texts over serial port"
- depends on 4xx
-
config PPC_EARLY_DEBUG
bool "Early debugging (dangerous)"
@@ -207,6 +203,24 @@
help
Select this to enable early debugging for Celleb with Beat.
+config PPC_EARLY_DEBUG_44x
+ bool "Early serial debugging for IBM/AMCC 44x CPUs"
+ depends on 44x
+ select PPC_UDBG_16550
+ help
+ Select this to enable early debugging for IBM 44x chips via the
+ inbuilt serial port.
+
endchoice
+config PPC_EARLY_DEBUG_44x_PHYSLOW
+ hex "Low 32 bits of early debug UART physical address"
+ depends PPC_EARLY_DEBUG_44x
+ default "0x40000200"
+
+config PPC_EARLY_DEBUG_44x_PHYSHIGH
+ hex "EPRN of early debug UART physical address"
+ depends PPC_EARLY_DEBUG_44x
+ default "0x1"
+
endmenu
diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S
index a51026f0..8869596 100644
--- a/arch/powerpc/kernel/head_44x.S
+++ b/arch/powerpc/kernel/head_44x.S
@@ -172,36 +172,28 @@
isync
4:
-#ifdef CONFIG_SERIAL_TEXT_DEBUG
- /*
- * Add temporary UART mapping for early debug.
- * We can map UART registers wherever we want as long as they don't
- * interfere with other system mappings (e.g. with pinned entries).
- * For an example of how we handle this - see ocotea.h. --ebs
- */
+#ifdef CONFIG_PPC_EARLY_DEBUG_44x
+ /* Add UART mapping for early debug. */
+
/* pageid fields */
- lis r3,UART0_IO_BASE@h
- ori r3,r3,PPC44x_TLB_VALID | PPC44x_TLB_4K
+ lis r3,PPC44x_EARLY_DEBUG_VIRTADDR@h
+ ori r3,r3,PPC44x_TLB_VALID|PPC44x_TLB_TS|PPC44x_TLB_64K
/* xlat fields */
- lis r4,UART0_PHYS_IO_BASE@h /* RPN depends on SoC */
-#ifndef CONFIG_440EP
- ori r4,r4,0x0001 /* ERPN is 1 for second 4GB page */
-#endif
+ lis r4,CONFIG_PPC_EARLY_DEBUG_44x_PHYSLOW@h
+ ori r4,r4,CONFIG_PPC_EARLY_DEBUG_44x_PHYSHIGH
/* attrib fields */
- li r5,0
- ori r5,r5,(PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_I | PPC44x_TLB_G)
+ li r5,(PPC44x_TLB_SW|PPC44x_TLB_SR|PPC44x_TLB_I|PPC44x_TLB_G)
+ li r0,62 /* TLB slot 0 */
- li r0,0 /* TLB slot 0 */
-
- tlbwe r3,r0,PPC44x_TLB_PAGEID /* Load the pageid fields */
- tlbwe r4,r0,PPC44x_TLB_XLAT /* Load the translation fields */
- tlbwe r5,r0,PPC44x_TLB_ATTRIB /* Load the attrib/access fields */
+ tlbwe r3,r0,PPC44x_TLB_PAGEID
+ tlbwe r4,r0,PPC44x_TLB_XLAT
+ tlbwe r5,r0,PPC44x_TLB_ATTRIB
/* Force context change */
isync
-#endif /* CONFIG_SERIAL_TEXT_DEBUG */
+#endif /* CONFIG_PPC_EARLY_DEBUG_44x */
/* Establish the interrupt vector offsets */
SET_IVOR(0, CriticalInput);
diff --git a/arch/powerpc/kernel/of_platform.c b/arch/powerpc/kernel/of_platform.c
index 908ed79..84c34d9 100644
--- a/arch/powerpc/kernel/of_platform.c
+++ b/arch/powerpc/kernel/of_platform.c
@@ -29,7 +29,6 @@
#include <asm/ppc-pci.h>
#include <asm/atomic.h>
-
/*
* The list of OF IDs below is used for matching bus types in the
* system whose devices are to be exposed as of_platform_devices.
diff --git a/arch/powerpc/kernel/udbg.c b/arch/powerpc/kernel/udbg.c
index 7e09718..7ef97ea 100644
--- a/arch/powerpc/kernel/udbg.c
+++ b/arch/powerpc/kernel/udbg.c
@@ -51,6 +51,9 @@
udbg_init_pas_realmode();
#elif defined(CONFIG_BOOTX_TEXT)
udbg_init_btext();
+#elif defined(CONFIG_PPC_EARLY_DEBUG_44x)
+ /* PPC44x debug */
+ udbg_init_44x_as1();
#endif
}
diff --git a/arch/powerpc/kernel/udbg_16550.c b/arch/powerpc/kernel/udbg_16550.c
index a963f65..7afab5b 100644
--- a/arch/powerpc/kernel/udbg_16550.c
+++ b/arch/powerpc/kernel/udbg_16550.c
@@ -191,3 +191,26 @@
udbg_getc_poll = NULL;
}
#endif /* CONFIG_PPC_MAPLE */
+
+#ifdef CONFIG_PPC_EARLY_DEBUG_44x
+#include <platforms/44x/44x.h>
+
+static void udbg_44x_as1_putc(char c)
+{
+ if (udbg_comport) {
+ while ((as1_readb(&udbg_comport->lsr) & LSR_THRE) == 0)
+ /* wait for idle */;
+ as1_writeb(c, &udbg_comport->thr); eieio();
+ if (c == '\n')
+ udbg_44x_as1_putc('\r');
+ }
+}
+
+void __init udbg_init_44x_as1(void)
+{
+ udbg_comport =
+ (volatile struct NS16550 __iomem *)PPC44x_EARLY_DEBUG_VIRTADDR;
+
+ udbg_putc = udbg_44x_as1_putc;
+}
+#endif /* CONFIG_PPC_EARLY_DEBUG_44x */
diff --git a/arch/powerpc/platforms/44x/44x.h b/arch/powerpc/platforms/44x/44x.h
index 45f24b1..42eabf8 100644
--- a/arch/powerpc/platforms/44x/44x.h
+++ b/arch/powerpc/platforms/44x/44x.h
@@ -1,6 +1,8 @@
#ifndef __POWERPC_PLATFORMS_44X_44X_H
#define __POWERPC_PLATFORMS_44X_44X_H
+extern u8 as1_readb(volatile u8 __iomem *addr);
+extern void as1_writeb(u8 data, volatile u8 __iomem *addr);
extern void ppc44x_reset_system(char *cmd);
#endif /* __POWERPC_PLATFORMS_44X_44X_H */
diff --git a/arch/powerpc/platforms/44x/misc_44x.S b/arch/powerpc/platforms/44x/misc_44x.S
index 52bde71..3bce71d 100644
--- a/arch/powerpc/platforms/44x/misc_44x.S
+++ b/arch/powerpc/platforms/44x/misc_44x.S
@@ -15,6 +15,37 @@
.text
/*
+ * Do an IO access in AS1
+ */
+_GLOBAL(as1_readb)
+ mfmsr r7
+ ori r0,r7,MSR_DS
+ sync
+ mtmsr r0
+ sync
+ isync
+ lbz r3,0(r3)
+ sync
+ mtmsr r7
+ sync
+ isync
+ blr
+
+_GLOBAL(as1_writeb)
+ mfmsr r7
+ ori r0,r7,MSR_DS
+ sync
+ mtmsr r0
+ sync
+ isync
+ stb r3,0(r4)
+ sync
+ mtmsr r7
+ sync
+ isync
+ blr
+
+/*
* void ppc44x_reset_system(char *cmd)
*
* At present, this routine just applies a system reset.
diff --git a/include/asm-powerpc/mmu-44x.h b/include/asm-powerpc/mmu-44x.h
index 7bbc37e..d5ce7a8 100644
--- a/include/asm-powerpc/mmu-44x.h
+++ b/include/asm-powerpc/mmu-44x.h
@@ -64,7 +64,13 @@
#endif /* !__ASSEMBLY__ */
+#ifndef CONFIG_PPC_EARLY_DEBUG_44x
#define PPC44x_EARLY_TLBS 1
+#else
+#define PPC44x_EARLY_TLBS 2
+#define PPC44x_EARLY_DEBUG_VIRTADDR (ASM_CONST(0xf0000000) \
+ | (ASM_CONST(CONFIG_PPC_EARLY_DEBUG_44x_PHYSLOW) & 0xffff))
+#endif
/* Size of the TLBs used for pinning in lowmem */
#define PPC_PIN_SIZE (1 << 28) /* 256M */
diff --git a/include/asm-powerpc/udbg.h b/include/asm-powerpc/udbg.h
index d03d855..ce9d82f 100644
--- a/include/asm-powerpc/udbg.h
+++ b/include/asm-powerpc/udbg.h
@@ -47,6 +47,7 @@
extern void __init udbg_init_rtas_console(void);
extern void __init udbg_init_debug_beat(void);
extern void __init udbg_init_btext(void);
+extern void __init udbg_init_44x_as1(void);
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_UDBG_H */