[PATCH 12/14] powerpc: Add early udbg support for 40x processors

[PATCH 12/14] powerpc: Add early udbg support for 40x processors

[Benjamin Herrenschmidt]

This adds some basic real mode based early udbg support for 40x
in order to debug things more easily

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

 arch/powerpc/Kconfig.debug             |   12 ++++++++++
 arch/powerpc/kernel/misc_32.S          |   39 +++++++++++++++++++++++++++++++++
 arch/powerpc/kernel/udbg.c             |    3 ++
 arch/powerpc/kernel/udbg_16550.c       |   33 +++++++++++++++++++++++++++
 arch/powerpc/platforms/Kconfig.cputype |    1 
 include/asm-powerpc/udbg.h             |    1 
 6 files changed, 89 insertions(+)

Index: linux-work/arch/powerpc/Kconfig.debug
===================================================================
--- linux-work.orig/arch/powerpc/Kconfig.debug	2007-11-21 12:44:03.000000000 +1100
+++ linux-work/arch/powerpc/Kconfig.debug	2007-11-21 12:47:58.000000000 +1100
@@ -220,6 +220,13 @@ config PPC_EARLY_DEBUG_44x
 	  Select this to enable early debugging for IBM 44x chips via the
 	  inbuilt serial port.
 
+config PPC_EARLY_DEBUG_40x
+	bool "Early serial debugging for IBM/AMCC 40x CPUs"
+	depends on 40x
+	help
+	  Select this to enable early debugging for IBM 40x chips via the
+	  inbuilt serial port.
+
 config PPC_EARLY_DEBUG_CPM
 	bool "Early serial debugging for Freescale CPM-based serial ports"
 	depends on SERIAL_CPM
@@ -241,6 +248,11 @@ config PPC_EARLY_DEBUG_44x_PHYSHIGH
 	depends on PPC_EARLY_DEBUG_44x
 	default "0x1"
 
+config PPC_EARLY_DEBUG_40x_PHYSADDR
+	hex "Early debug UART physical address"
+	depends on PPC_EARLY_DEBUG_40x
+	default "0xef600300"
+
 config PPC_EARLY_DEBUG_CPM_ADDR
 	hex "CPM UART early debug transmit descriptor address"
 	depends on PPC_EARLY_DEBUG_CPM
Index: linux-work/arch/powerpc/kernel/misc_32.S
===================================================================
--- linux-work.orig/arch/powerpc/kernel/misc_32.S	2007-11-21 12:40:26.000000000 +1100
+++ linux-work/arch/powerpc/kernel/misc_32.S	2007-11-21 12:41:43.000000000 +1100
@@ -206,6 +206,45 @@ _GLOBAL(_nmask_and_or_msr)
 	isync
 	blr			/* Done */
 
+#ifdef CONFIG_40x
+
+/*
+ * Do an IO access in real mode
+ */
+_GLOBAL(real_readb)
+	mfmsr	r7
+	ori	r0,r7,MSR_DR
+	xori	r0,r0,MSR_DR
+	sync
+	mtmsr	r0
+	sync
+	isync
+	lbz	r3,0(r3)
+	sync
+	mtmsr	r7
+	sync
+	isync
+	blr
+
+	/*
+ * Do an IO access in real mode
+ */
+_GLOBAL(real_writeb)
+	mfmsr	r7
+	ori	r0,r7,MSR_DR
+	xori	r0,r0,MSR_DR
+	sync
+	mtmsr	r0
+	sync
+	isync
+	stb	r3,0(r4)
+	sync
+	mtmsr	r7
+	sync
+	isync
+	blr
+
+#endif /* CONFIG_40x */
 
 /*
  * Flush MMU TLB
Index: linux-work/arch/powerpc/kernel/udbg.c
===================================================================
--- linux-work.orig/arch/powerpc/kernel/udbg.c	2007-11-21 12:38:11.000000000 +1100
+++ linux-work/arch/powerpc/kernel/udbg.c	2007-11-21 12:44:50.000000000 +1100
@@ -54,6 +54,9 @@ void __init udbg_early_init(void)
 #elif defined(CONFIG_PPC_EARLY_DEBUG_44x)
 	/* PPC44x debug */
 	udbg_init_44x_as1();
+#elif defined(CONFIG_PPC_EARLY_DEBUG_40x)
+	/* PPC40x debug */
+	udbg_init_40x_realmode();
 #elif defined(CONFIG_PPC_EARLY_DEBUG_CPM)
 	udbg_init_cpm();
 #endif
Index: linux-work/arch/powerpc/kernel/udbg_16550.c
===================================================================
--- linux-work.orig/arch/powerpc/kernel/udbg_16550.c	2007-11-21 12:42:24.000000000 +1100
+++ linux-work/arch/powerpc/kernel/udbg_16550.c	2007-11-21 12:50:40.000000000 +1100
@@ -225,3 +225,36 @@ void __init udbg_init_44x_as1(void)
 	udbg_getc = udbg_44x_as1_getc;
 }
 #endif /* CONFIG_PPC_EARLY_DEBUG_44x */
+
+#ifdef CONFIG_PPC_EARLY_DEBUG_40x
+static void udbg_40x_real_putc(char c)
+{
+	if (udbg_comport) {
+		while ((real_readb(&udbg_comport->lsr) & LSR_THRE) == 0)
+			/* wait for idle */;
+		real_writeb(c, &udbg_comport->thr); eieio();
+		if (c == '\n')
+			udbg_40x_real_putc('\r');
+	}
+}
+
+static int udbg_40x_real_getc(void)
+{
+	if (udbg_comport) {
+		while ((real_readb(&udbg_comport->lsr) & LSR_DR) == 0)
+			; /* wait for char */
+		return real_readb(&udbg_comport->rbr);
+	}
+	return -1;
+}
+
+void __init udbg_init_40x_realmode(void)
+{
+	udbg_comport = (volatile struct NS16550 __iomem *)
+		CONFIG_PPC_EARLY_DEBUG_40x_PHYSADDR;
+
+	udbg_putc = udbg_40x_real_putc;
+	udbg_getc = udbg_40x_real_getc;
+	udbg_getc_poll = NULL;
+}
+#endif /* CONFIG_PPC_EARLY_DEBUG_40x */
Index: linux-work/include/asm-powerpc/udbg.h
===================================================================
--- linux-work.orig/include/asm-powerpc/udbg.h	2007-11-21 12:44:31.000000000 +1100
+++ linux-work/include/asm-powerpc/udbg.h	2007-11-21 12:44:45.000000000 +1100
@@ -48,6 +48,7 @@ extern void __init udbg_init_rtas_consol
 extern void __init udbg_init_debug_beat(void);
 extern void __init udbg_init_btext(void);
 extern void __init udbg_init_44x_as1(void);
+extern void __init udbg_init_40x_realmode(void);
 extern void __init udbg_init_cpm(void);
 
 #endif /* __KERNEL__ */
Index: linux-work/arch/powerpc/platforms/Kconfig.cputype
===================================================================
--- linux-work.orig/arch/powerpc/platforms/Kconfig.cputype	2007-11-21 12:50:16.000000000 +1100
+++ linux-work/arch/powerpc/platforms/Kconfig.cputype	2007-11-21 12:50:18.000000000 +1100
@@ -43,6 +43,7 @@ config 40x
 	bool "AMCC 40x"
 	select PPC_DCR_NATIVE
 	select WANT_DEVICE_TREE
+	select PPC_UDBG_16550
 
 config 44x
 	bool "AMCC 44x"

Re: [PATCH 12/14] powerpc: Add early udbg support for 40x processors

[Grant Likely]

On 11/20/07, Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:
> This adds some basic real mode based early udbg support for 40x
> in order to debug things more easily
>
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> ---
> --- linux-work.orig/arch/powerpc/platforms/Kconfig.cputype      2007-11-21 12:50:16.000000000 +1100
> +++ linux-work/arch/powerpc/platforms/Kconfig.cputype   2007-11-21 12:50:18.000000000 +1100
> @@ -43,6 +43,7 @@ config 40x
>         bool "AMCC 40x"
>         select PPC_DCR_NATIVE
>         select WANT_DEVICE_TREE
> +       select PPC_UDBG_16550

Unfortunately, this isn't always true.  The Xilinx Virtex parts us
config 40x, but not all FPGA bitstreams have a 16550 serial port.
Sometimes it's a uartlite instead.

Cheers,
g.

-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.
grant.likely@secretlab.ca
(403) 399-0195

Re: [PATCH 12/14] powerpc: Add early udbg support for 40x processors

[Benjamin Herrenschmidt]

On Wed, 2007-11-21 at 16:47 -0700, Grant Likely wrote:
> On 11/20/07, Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:
> > This adds some basic real mode based early udbg support for 40x
> > in order to debug things more easily
> >
> > Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> > ---
> > --- linux-work.orig/arch/powerpc/platforms/Kconfig.cputype      2007-11-21 12:50:16.000000000 +1100
> > +++ linux-work/arch/powerpc/platforms/Kconfig.cputype   2007-11-21 12:50:18.000000000 +1100
> > @@ -43,6 +43,7 @@ config 40x
> >         bool "AMCC 40x"
> >         select PPC_DCR_NATIVE
> >         select WANT_DEVICE_TREE
> > +       select PPC_UDBG_16550
> 
> Unfortunately, this isn't always true.  The Xilinx Virtex parts us
> config 40x, but not all FPGA bitstreams have a 16550 serial port.
> Sometimes it's a uartlite instead.

What does uartlite looks like ?

Ben.

Re: [PATCH 12/14] powerpc: Add early udbg support for 40x processors

[Grant Likely]

On 11/21/07, Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:
>
> On Wed, 2007-11-21 at 16:47 -0700, Grant Likely wrote:
> > On 11/20/07, Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:
> > > This adds some basic real mode based early udbg support for 40x
> > > in order to debug things more easily
> > >
> > > Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> > > ---
> > > --- linux-work.orig/arch/powerpc/platforms/Kconfig.cputype      2007-11-21 12:50:16.000000000 +1100
> > > +++ linux-work/arch/powerpc/platforms/Kconfig.cputype   2007-11-21 12:50:18.000000000 +1100
> > > @@ -43,6 +43,7 @@ config 40x
> > >         bool "AMCC 40x"
> > >         select PPC_DCR_NATIVE
> > >         select WANT_DEVICE_TREE
> > > +       select PPC_UDBG_16550
> >
> > Unfortunately, this isn't always true.  The Xilinx Virtex parts us
> > config 40x, but not all FPGA bitstreams have a 16550 serial port.
> > Sometimes it's a uartlite instead.
>
> What does uartlite looks like ?

fixed speed
4 registers: rx, tx, status & control

rx & tx are... well... rx and tx registers
status has a number of bits reporting fifos full/empty etc.
control has three bits; reset tx, reset rx and interrupt enable.

See the top of drivers/serial/uartlite.c

Very simple stuff; but definitely not 16550.

g.

-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.
grant.likely@secretlab.ca
(403) 399-0195

Re: [PATCH 12/14] powerpc: Add early udbg support for 40x processors

[Benjamin Herrenschmidt]

> fixed speed
> 4 registers: rx, tx, status & control
> 
> rx & tx are... well... rx and tx registers
> status has a number of bits reporting fifos full/empty etc.
> control has three bits; reset tx, reset rx and interrupt enable.
> 
> See the top of drivers/serial/uartlite.c
> 
> Very simple stuff; but definitely not 16550.

Yuck, they could have made it look like 16550 at least...

Oh well, that's allright, select'ing it wont break anything anyway.

Ultimately, we can if we want have a list of all support 40x (and 4xx)
variants and select what we want in a given kernel build. Those variants
would themselves select the individual bits they care about...

Ben.