From: Lu Baolu <baolu.lu@linux.intel.com>
Date: Tue, 21 Mar 2017 08:01:31 +0000 (+0800)
Subject: x86/earlyprintk: Add support for earlyprintk via USB3 debug port
X-Git-Tag: MMI-PSA29.97-13-9~5729^2~2
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=1b5aeebf3a92273b4d85aeff37a16037bc3c3abf;p=GitHub%2FMotorolaMobilityLLC%2Fkernel-slsi.git

x86/earlyprintk: Add support for earlyprintk via USB3 debug port

Add support for earlyprintk by writing debug messages to the
USB3 debug port. Users can use this type of early printk by
specifying the kernel parameter of "earlyprintk=xdbc". This
gives users a chance of providing debugging output.

The hardware for USB3 debug port requires DMA memory blocks.
This requires to delay setting up debugging hardware and
registering boot console until the memblocks are filled.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathias Nyman <mathias.nyman@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-usb@vger.kernel.org
Link: http://lkml.kernel.org/r/1490083293-3792-4-git-send-email-baolu.lu@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 2ba45caabada..ea1293d60f17 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -989,6 +989,7 @@
 			earlyprintk=ttySn[,baudrate]
 			earlyprintk=dbgp[debugController#]
 			earlyprintk=pciserial,bus:device.function[,baudrate]
+			earlyprintk=xdbc[xhciController#]
 
 			earlyprintk is useful when the kernel crashes before
 			the normal console is initialized. It is not enabled by
diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index 8a121991e5ba..0f0840304452 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -17,6 +17,7 @@
 #include <asm/intel-mid.h>
 #include <asm/pgtable.h>
 #include <linux/usb/ehci_def.h>
+#include <linux/usb/xhci-dbgp.h>
 #include <linux/efi.h>
 #include <asm/efi.h>
 #include <asm/pci_x86.h>
@@ -381,6 +382,10 @@ static int __init setup_early_printk(char *buf)
 		if (!strncmp(buf, "efi", 3))
 			early_console_register(&early_efi_console, keep);
 #endif
+#ifdef CONFIG_EARLY_PRINTK_USB_XDBC
+		if (!strncmp(buf, "xdbc", 4))
+			early_xdbc_parse_parameter(buf + 4);
+#endif
 
 		buf++;
 	}
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index e70204e13e48..2600b1d0043b 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -70,6 +70,7 @@
 #include <linux/tboot.h>
 #include <linux/jiffies.h>
 
+#include <linux/usb/xhci-dbgp.h>
 #include <video/edid.h>
 
 #include <asm/mtrr.h>
@@ -1144,6 +1145,9 @@ void __init setup_arch(char **cmdline_p)
 	memblock_set_current_limit(ISA_END_ADDRESS);
 	memblock_x86_fill();
 
+	if (!early_xdbc_setup_hardware())
+		early_xdbc_register_console();
+
 	reserve_bios_regions();
 
 	if (efi_enabled(EFI_MEMMAP)) {