[PATCH v2 0/2] MIPS: BMIPS: Improved early panic support

[PATCH v2 0/2] MIPS: BMIPS: Improved early panic support

[Florian Fainelli]

Hi Thomas,

This patch series adds support for cfe_die() which can be used during
early platform initialization when we do not yet have a valid DTB to
infer an earlycon console from. This is useful while bringing up new
platforms/DTBs as well.

Thanks!

Changes in v2:

- ensure that we do not break multi-CPU builds by reading the CPU's PrID
  to perform the appropriate XKS01 disabling before handing over to CFE

Florian Fainelli (2):
  MIPS: CFE: Add cfe_die()
  MIPS: BMIPS: Utilize cfe_die() for invalid DTB

 arch/mips/Kconfig                      |  1 +
 arch/mips/bmips/setup.c                | 14 +++++-
 arch/mips/fw/cfe/cfe_api.c             | 68 +++++++++++++++++++++++++-
 arch/mips/include/asm/fw/cfe/cfe_api.h |  2 +
 4 files changed, 83 insertions(+), 2 deletions(-)

-- 
2.25.1

[PATCH v2 1/2] MIPS: CFE: Add cfe_die()

[Florian Fainelli]

Add a cfe_die() implementation which is useful when the kernel does an
early panic and no console is registered. This allows us to print
useful diagnostics such as an invalid DTB having been
configured/selected.

Since the BMIPS_GENERIC kernel can be built with support for multiple
processors, we need to do a runtime determination of the type of CPU
that we are executing on to perform the appropriate XKS01 disabling.

Since cfe_init() + cfe_die() could be conceivably called at very early
stages of the kernel boot, before cpu_probe(), we do not rely on the
structure(s) populated by cpu_probe().

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 arch/mips/fw/cfe/cfe_api.c             | 68 +++++++++++++++++++++++++-
 arch/mips/include/asm/fw/cfe/cfe_api.h |  2 +
 2 files changed, 69 insertions(+), 1 deletion(-)

diff --git a/arch/mips/fw/cfe/cfe_api.c b/arch/mips/fw/cfe/cfe_api.c
index 0c9c97ab291e..dcdfd962dbde 100644
--- a/arch/mips/fw/cfe/cfe_api.c
+++ b/arch/mips/fw/cfe/cfe_api.c
@@ -13,10 +13,15 @@
  *
  * Authors:  Mitch Lichtenberg, Chris Demetriou
  */
-
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/printk.h>
+#include <asm/mipsregs.h>
 #include <asm/fw/cfe/cfe_api.h>
 #include "cfe_api_int.h"
 
+unsigned long __initdata cfe_seal;
+
 /* Cast from a native pointer to a cfe_xptr_t and back.	 */
 #define XPTR_FROM_NATIVE(n)	((cfe_xptr_t) (intptr_t) (n))
 #define NATIVE_FROM_XPTR(x)	((void *) (intptr_t) (x))
@@ -412,3 +417,64 @@ int cfe_writeblk(int handle, s64 offset, const char *buffer, int length)
 		return xiocb.xiocb_status;
 	return xiocb.plist.xiocb_buffer.buf_retlen;
 }
+
+void __init cfe_die(char *fmt, ...)
+{
+	unsigned int prid, __maybe_unused rev;
+	char msg[128];
+	va_list ap;
+	int handle;
+	unsigned int count;
+
+	va_start(ap, fmt);
+	vsprintf(msg, fmt, ap);
+	strcat(msg, "\r\n");
+
+	if (cfe_seal != CFE_EPTSEAL)
+		goto no_cfe;
+
+	prid = read_c0_prid();
+	if ((prid & PRID_COMP_MASK) != PRID_COMP_BROADCOM)
+		goto no_cfe;
+
+	rev = prid & PRID_REV_MASK;
+
+	/* disable XKS01 so that CFE can access the registers */
+	switch (prid & PRID_IMP_MASK) {
+#ifdef CONFIG_CPU_BMIPS4380
+	case PRID_IMP_BMIPS43XX:
+		if (rev >= PRID_REV_BMIPS4380_LO &&
+		    rev <= PRID_REV_BMIPS4380_HI)
+			__write_32bit_c0_register($22, 3,
+				__read_32bit_c0_register($22, 3) & ~BIT(12));
+		break;
+#endif
+#ifdef CONFIG_CPU_BMIPS5000
+	case PRID_IMP_BMIPS5000:
+	case PRID_IMP_BMIPS5200:
+		__write_32bit_c0_register($22, 5,
+			__read_32bit_c0_register($22, 5) & ~BIT(8));
+		break;
+#endif
+	default:
+		break;
+	}
+
+	handle = cfe_getstdhandle(CFE_STDHANDLE_CONSOLE);
+	if (handle < 0)
+		goto no_cfe;
+
+	cfe_write(handle, msg, strlen(msg));
+
+	for (count = 0; count < 0x7fffffff; count++)
+		mb();
+	cfe_exit(0, 1);
+	while (1)
+		;
+
+no_cfe:
+	/* probably won't print anywhere useful */
+	panic("%s", msg);
+
+	va_end(ap);
+}
diff --git a/arch/mips/include/asm/fw/cfe/cfe_api.h b/arch/mips/include/asm/fw/cfe/cfe_api.h
index 6457f36897a2..25df2f4deb31 100644
--- a/arch/mips/include/asm/fw/cfe/cfe_api.h
+++ b/arch/mips/include/asm/fw/cfe/cfe_api.h
@@ -105,5 +105,7 @@ int cfe_setenv(char *name, char *val);
 int cfe_write(int handle, const char *buffer, int length);
 int cfe_writeblk(int handle, int64_t offset, const char *buffer,
 		 int length);
+extern unsigned long cfe_seal;
+__printf(1, 2) void cfe_die(char *fmt, ...);
 
 #endif				/* CFE_API_H */
-- 
2.25.1

[PATCH v2 2/2] MIPS: BMIPS: Utilize cfe_die() for invalid DTB

[Florian Fainelli]

If we were not specified a correct DTB, we will not be able to print
anything useful with panic() which requires a working console of some
sort. Utilize cfe_die() to callback into the CFE default UART and print
some useful diagnostics.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 arch/mips/Kconfig       |  1 +
 arch/mips/bmips/setup.c | 14 +++++++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 8db38817320b..0c366088b707 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -294,6 +294,7 @@ config BMIPS_GENERIC
 	select HARDIRQS_SW_RESEND
 	select HAVE_PCI
 	select PCI_DRIVERS_GENERIC
+	select FW_CFE
 	help
 	  Build a generic DT-based kernel image that boots on select
 	  BCM33xx cable modem chips, BCM63xx DSL chips, and BCM7xxx set-top
diff --git a/arch/mips/bmips/setup.c b/arch/mips/bmips/setup.c
index 31bcfa4e08b9..e95b3f78e7cd 100644
--- a/arch/mips/bmips/setup.c
+++ b/arch/mips/bmips/setup.c
@@ -28,6 +28,7 @@
 #include <asm/smp-ops.h>
 #include <asm/time.h>
 #include <asm/traps.h>
+#include <asm/fw/cfe/cfe_api.h>
 
 #define RELO_NORMAL_VEC		BIT(18)
 
@@ -123,8 +124,19 @@ static const struct bmips_quirk bmips_quirk_list[] = {
 	{ },
 };
 
+static void __init bmips_init_cfe(void)
+{
+	cfe_seal = fw_arg3;
+
+	if (cfe_seal != CFE_EPTSEAL)
+		return;
+
+	cfe_init(fw_arg0, fw_arg2);
+}
+
 void __init prom_init(void)
 {
+	bmips_init_cfe();
 	bmips_cpu_setup();
 	register_bmips_smp_ops();
 }
@@ -165,7 +177,7 @@ void __init plat_mem_setup(void)
 		dtb = get_fdt();
 
 	if (!dtb)
-		panic("no dtb found");
+		cfe_die("no dtb found");
 
 	__dt_setup_arch(dtb);
 
-- 
2.25.1

Re: [PATCH v2 0/2] MIPS: BMIPS: Improved early panic support

[Thomas Bogendoerfer]

On Fri, Jul 15, 2022 at 02:37:45PM -0700, Florian Fainelli wrote:
> Hi Thomas,
> 
> This patch series adds support for cfe_die() which can be used during
> early platform initialization when we do not yet have a valid DTB to
> infer an earlycon console from. This is useful while bringing up new
> platforms/DTBs as well.
> 
> Thanks!
> 
> Changes in v2:
> 
> - ensure that we do not break multi-CPU builds by reading the CPU's PrID
>   to perform the appropriate XKS01 disabling before handing over to CFE
> 
> Florian Fainelli (2):
>   MIPS: CFE: Add cfe_die()
>   MIPS: BMIPS: Utilize cfe_die() for invalid DTB
> 
>  arch/mips/Kconfig                      |  1 +
>  arch/mips/bmips/setup.c                | 14 +++++-
>  arch/mips/fw/cfe/cfe_api.c             | 68 +++++++++++++++++++++++++-
>  arch/mips/include/asm/fw/cfe/cfe_api.h |  2 +
>  4 files changed, 83 insertions(+), 2 deletions(-)

series applied to mips-next.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]