Merge branch 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 debug updates from Ingo Molnar:
 "The biggest update is the addition of USB3 debug port based
  early-console.

  Greg was fine with the USB changes and with the routing of these
  patches:

    https://www.spinics.net/lists/linux-usb/msg155093.html"

* 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  usb/doc: Add document for USB3 debug port usage
  usb/serial: Add DBC debug device support to usb_debug
  x86/earlyprintk: Add support for earlyprintk via USB3 debug port
  usb/early: Add driver for xhci debug capability
  x86/timers: Add simple udelay calibration

3 files changed, 56 insertions, 2 deletions

diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 63c1d13aaf9f..fcb7604172ce 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -5,6 +5,9 @@ config TRACE_IRQFLAGS_SUPPORT
 
 source "lib/Kconfig.debug"
 
+config EARLY_PRINTK_USB
+	bool
+
 config X86_VERBOSE_BOOTUP
 	bool "Enable verbose x86 bootup info messages"
 	default y
@@ -23,19 +26,20 @@ config EARLY_PRINTK
 	  This is useful for kernel debugging when your machine crashes very
 	  early before the console code is initialized. For normal operation
 	  it is not recommended because it looks ugly and doesn't cooperate
-	  with klogd/syslogd or the X server. You should normally N here,
+	  with klogd/syslogd or the X server. You should normally say N here,
 	  unless you want to debug such a crash.
 
 config EARLY_PRINTK_DBGP
 	bool "Early printk via EHCI debug port"
 	depends on EARLY_PRINTK && PCI
+	select EARLY_PRINTK_USB
 	---help---
 	  Write kernel log output directly into the EHCI debug port.
 
 	  This is useful for kernel debugging when your machine crashes very
 	  early before the console code is initialized. For normal operation
 	  it is not recommended because it looks ugly and doesn't cooperate
-	  with klogd/syslogd or the X server. You should normally N here,
+	  with klogd/syslogd or the X server. You should normally say N here,
 	  unless you want to debug such a crash. You need usb debug device.
 
 config EARLY_PRINTK_EFI
@@ -48,6 +52,25 @@ config EARLY_PRINTK_EFI
 	  This is useful for kernel debugging when your machine crashes very
 	  early before the console code is initialized.
 
+config EARLY_PRINTK_USB_XDBC
+	bool "Early printk via the xHCI debug port"
+	depends on EARLY_PRINTK && PCI
+	select EARLY_PRINTK_USB
+	---help---
+	  Write kernel log output directly into the xHCI debug port.
+
+	  One use for this feature is kernel debugging, for example when your
+	  machine crashes very early before the regular console code is
+	  initialized. Other uses include simpler, lockless logging instead of
+	  a full-blown printk console driver + klogd.
+
+	  For normal production environments this is normally not recommended,
+	  because it doesn't feed events into klogd/syslogd and doesn't try to
+	  print anything on the screen.
+
+	  You should normally say N here, unless you want to debug early
+	  crashes or need a very simple printk logging facility.
+
 config X86_PTDUMP_CORE
 	def_bool n
 
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 62a1c74855e5..0b4d3c686b1e 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>
@@ -811,6 +812,26 @@ dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p)
 	return 0;
 }
 
+static void __init simple_udelay_calibration(void)
+{
+	unsigned int tsc_khz, cpu_khz;
+	unsigned long lpj;
+
+	if (!boot_cpu_has(X86_FEATURE_TSC))
+		return;
+
+	cpu_khz = x86_platform.calibrate_cpu();
+	tsc_khz = x86_platform.calibrate_tsc();
+
+	tsc_khz = tsc_khz ? : cpu_khz;
+	if (!tsc_khz)
+		return;
+
+	lpj = tsc_khz * 1000;
+	do_div(lpj, HZ);
+	loops_per_jiffy = lpj;
+}
+
 /*
  * Determine if we were loaded by an EFI loader.  If so, then we have also been
  * passed the efi memmap, systab, etc., so we should use these data structures
@@ -959,6 +980,8 @@ void __init setup_arch(char **cmdline_p)
 	 */
 	x86_configure_nx();
 
+	simple_udelay_calibration();
+
 	parse_early_param();
 
 #ifdef CONFIG_MEMORY_HOTPLUG
@@ -1095,6 +1118,9 @@ void __init setup_arch(char **cmdline_p)
 	memblock_set_current_limit(ISA_END_ADDRESS);
 	e820__memblock_setup();
 
+	if (!early_xdbc_setup_hardware())
+		early_xdbc_register_console();
+
 	reserve_bios_regions();
 
 	if (efi_enabled(EFI_MEMMAP)) {