[PATCH] powerpc: Make early debugging configurable via Kconfig

This patch adds Kconfig entries to control the early debugging options,
currently in setup_64.c.

Doing this via Kconfig rather than #defines means you can have one source tree,
which is buildable for multiple platforms - and you can enable the correct
early debug option for each platform via .config.

I made udbg_early_init() a static inline because otherwise GCC is to daft to
optimise it away when debugging is off.

Now that we have udbg_init_rtas() we can make call_rtas_display_status* static.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

6 files changed, 80 insertions, 41 deletions

diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index 30a30bf559ea..9254806f7032 100644
--- a/arch/powerpc/Kconfig.debug
+++ b/arch/powerpc/Kconfig.debug
@@ -115,4 +115,46 @@ config PPC_OCP
         depends on IBM_OCP || XILINX_OCP
         default y
 
+choice
+        prompt "Early debugging (dangerous)"
+        bool
+        optional
+        help
+          Enable early debugging. Careful, if you enable debugging for the
+          wrong type of machine your kernel _will not boot_.
+
+config PPC_EARLY_DEBUG_LPAR
+        bool "LPAR HV Console"
+        depends on PPC_PSERIES
+        help
+          Select this to enable early debugging for a machine with a HVC
+          console on vterm 0.
+
+config PPC_EARLY_DEBUG_G5
+        bool "Apple G5"
+        depends on PPC_PMAC64
+        help
+          Select this to enable early debugging for Apple G5 machines.
+
+config PPC_EARLY_DEBUG_RTAS
+        bool "RTAS Panel"
+        depends on PPC_RTAS
+        help
+          Select this to enable early debugging via the RTAS panel.
+
+config PPC_EARLY_DEBUG_MAPLE
+        bool "Maple real mode"
+        depends on PPC_MAPLE
+        help
+          Select this to enable early debugging for Maple.
+
+config PPC_EARLY_DEBUG_ISERIES
+        bool "iSeries HV Console"
+        depends on PPC_ISERIES
+        help
+          Select this to enable early debugging for legacy iSeries. You need
+          to hit "Ctrl-x Ctrl-x" to see the messages on the console.
+
+endchoice
+
 endmenu
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index ae2e2a31a705..68bcd2824bc6 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -29,6 +29,7 @@
 #include <asm/delay.h>
 #include <asm/uaccess.h>
 #include <asm/lmb.h>
+#include <asm/udbg.h>
 
 struct rtas_t rtas = {
         .lock = SPIN_LOCK_UNLOCKED
@@ -52,7 +53,7 @@ EXPORT_SYMBOL(rtas_flash_term_hook);
  * are designed only for very early low-level debugging, which
  * is why the token is hard-coded to 10.
  */
-void call_rtas_display_status(unsigned char c)
+static void call_rtas_display_status(char c)
 {
         struct rtas_args *args = &rtas.args;
         unsigned long s;
@@ -65,14 +66,14 @@ void call_rtas_display_status(unsigned char c)
         args->nargs = 1;
         args->nret  = 1;
         args->rets  = (rtas_arg_t *)&(args->args[1]);
-        args->args[0] = (int)c;
+        args->args[0] = (unsigned char)c;
 
         enter_rtas(__pa(args));
 
         spin_unlock_irqrestore(&rtas.lock, s);
 }
 
-void call_rtas_display_status_delay(unsigned char c)
+static void call_rtas_display_status_delay(char c)
 {
         static int pending_newline = 0;  /* did last write end with unprinted newline? */
         static int width = 16;
@@ -96,6 +97,11 @@ void call_rtas_display_status_delay(unsigned char c)
         }
 }
 
+void __init udbg_init_rtas(void)
+{
+        udbg_putc = call_rtas_display_status_delay;
+}
+
 void rtas_progress(char *s, unsigned short hex)
 {
         struct device_node *root;
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 177d8249078d..0420418f317a 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -70,37 +70,6 @@
 #define DBG(fmt...)
 #endif
 
-/*
- * Here are some early debugging facilities. You can enable one
- * but your kernel will not boot on anything else if you do so
- */
-
-/* For use on LPAR machines that support an HVC console on vterm 0 */
-extern void udbg_init_debug_lpar(void);
-
-/* This one is for use on Apple G5 machines */
-extern void udbg_init_pmac_realmode(void);
-
-/* That's RTAS panel debug */
-extern void call_rtas_display_status_delay(unsigned char c);
-
-/* Here's maple real mode debug */
-extern void udbg_init_maple_realmode(void);
-
-/* For iSeries - hit Ctrl-x Ctrl-x to see the output */
-extern void udbg_init_iseries(void);
-
-#define EARLY_DEBUG_INIT() do {} while(0)
-
-#if 0
-#define EARLY_DEBUG_INIT() udbg_init_debug_lpar()
-#define EARLY_DEBUG_INIT() udbg_init_iseries()
-#define EARLY_DEBUG_INIT() udbg_init_maple_realmode()
-#define EARLY_DEBUG_INIT() udbg_init_pmac_realmode()
-#define EARLY_DEBUG_INIT()                                              \
-        do { udbg_putc = call_rtas_display_status_delay; } while(0)
-#endif
-
 int have_of = 1;
 int boot_cpuid = 0;
 int boot_cpuid_phys = 0;
@@ -241,11 +210,8 @@ void __init early_setup(unsigned long dt_ptr)
         struct paca_struct *lpaca = get_paca();
         static struct machdep_calls **mach;
 
-        /*
-         * Enable early debugging if any specified (see top of
-         * this file)
-         */
-        EARLY_DEBUG_INIT();
+        /* Enable early debugging if any specified (see udbg.h) */
+        udbg_early_init();
 
         DBG(" -> early_setup()\n");
 
diff --git a/arch/powerpc/kernel/udbg.c b/arch/powerpc/kernel/udbg.c
index 558c1ceb2b93..3774e80094f5 100644
--- a/arch/powerpc/kernel/udbg.c
+++ b/arch/powerpc/kernel/udbg.c
@@ -15,11 +15,36 @@
 #include <linux/sched.h>
 #include <linux/console.h>
 #include <asm/processor.h>
+#include <asm/udbg.h>
 
 void (*udbg_putc)(char c);
 int (*udbg_getc)(void);
 int (*udbg_getc_poll)(void);
 
+/*
+ * Early debugging facilities. You can enable _one_ of these via .config,
+ * if you do so your kernel _will not boot_ on anything else. Be careful.
+ */
+void __init udbg_early_init(void)
+{
+#if defined(CONFIG_PPC_EARLY_DEBUG_LPAR)
+        /* For LPAR machines that have an HVC console on vterm 0 */
+        udbg_init_debug_lpar();
+#elif defined(CONFIG_PPC_EARLY_DEBUG_G5)
+        /* For use on Apple G5 machines */
+        udbg_init_pmac_realmode();
+#elif defined(CONFIG_PPC_EARLY_DEBUG_RTAS)
+        /* RTAS panel debug */
+        udbg_init_rtas();
+#elif defined(CONFIG_PPC_EARLY_DEBUG_MAPLE)
+        /* Maple real mode debug */
+        udbg_init_maple_realmode();
+#elif defined(CONFIG_PPC_EARLY_DEBUG_ISERIES)
+        /* For iSeries - hit Ctrl-x Ctrl-x to see the output */
+        udbg_init_iseries();
+#endif
+}
+
 /* udbg library, used by xmon et al */
 void udbg_puts(const char *s)
 {
diff --git a/arch/powerpc/kernel/udbg_16550.c b/arch/powerpc/kernel/udbg_16550.c
index 7541bf44d2da..2da65a9c93f6 100644
--- a/arch/powerpc/kernel/udbg_16550.c
+++ b/arch/powerpc/kernel/udbg_16550.c
@@ -155,7 +155,7 @@ void udbg_maple_real_putc(unsigned char c)
         }
 }
 
-void udbg_init_maple_realmode(void)
+void __init udbg_init_maple_realmode(void)
 {
         udbg_comport = (volatile struct NS16550 __iomem *)0xf40003f8;
 
diff --git a/arch/powerpc/platforms/powermac/udbg_scc.c b/arch/powerpc/platforms/powermac/udbg_scc.c
index e87d53acfb61..c4352a8db644 100644
--- a/arch/powerpc/platforms/powermac/udbg_scc.c
+++ b/arch/powerpc/platforms/powermac/udbg_scc.c
@@ -153,7 +153,7 @@ static void udbg_real_scc_putc(char c)
                 udbg_real_scc_putc('\r');
 }
 
-void udbg_init_pmac_realmode(void)
+void __init udbg_init_pmac_realmode(void)
 {
         sccc = (volatile u8 __iomem *)0x80013020ul;
         sccd = (volatile u8 __iomem *)0x80013030ul;