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Commit d57c33c5 (add generic fixmap.h) added (among other
similar things) set_fixmap_io to deal with early ioremap of devices.

More recently, commit bf4b558e (arm64: add early_ioremap support)
converted the arm64 earlyprintk to use set_fixmap_io. A side effect of
this conversion is that my virtual machines have stopped booting when
I pass "earlyprintk=uart8250-8bit,0x3f8" to the guest kernel.

Turns out that the new earlyprintk code doesn't care at all about
sub-page offsets, and just assumes that the earlyprintk device will
be page-aligned. Obviously, that doesn't play well with the above example.

Further investigation shows that set_fixmap_io uses __set_fixmap instead
of __set_fixmap_offset. A fix is to introduce a set_fixmap_offset_io that
uses the latter, and to remove the superflous call to fix_to_virt
(which only returns the value that set_fixmap_io has already given us).

With this applied, my VMs are back in business. Tested on a Cortex-A57
platform with kvmtool as platform emulation.

Cc: Will Deacon <will.deacon@arm.com>
Acked-by: Mark Salter <msalter@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Add support for early IO or memory mappings which are needed before the
normal ioremap() is usable.  This also adds fixmap support for permanent
fixed mappings such as that used by the earlyprintk device register
region.
Signed-off-by: Mark Salter <msalter@redhat.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Borislav Petkov <borislav.petkov@amd.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When compiling with allmodconfig. early_console is already defined as an
extern global pointer. Need let it point to the object which we intend
to (like arm32 done).
Signed-off-by: Chen Gang <gang.chen@asianux.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

This patch adds support for using earlyprintk with 8250/16550 UART
ports. The 8250/16550 UART can either have 8-bit or 32-bit aligned
registers which is HW vendor dependent.

Kernel args for 8-bit aligned regs: earlyprintk=uart8250-8bit,<phys_address>

Kernel args for 32-bit aligned regs: earlyprintk=uart8250-32bit,<phys_address>
Signed-off-by: Anup Patel <anup.patel@linaro.org>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Enable early_printk to use the FastModel semihosting to output
the early kernel messages. Works both for host and guest kernels.

To use this feature, pass "early_printk=smh" to the kernel.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

This patch adds support for "earlyprintk=" parameter on the kernel
command line. The format is:

  earlyprintk=<name>[,<addr>][,<options>]

where <name> is the name of the (UART) device, e.g. "pl011", <addr> is
the I/O address. The <options> aren't currently used.

The mapping of the earlyprintk device is done very early during kernel
boot and there are restrictions on which functions it can call. A
special early_io_map() function is added which creates the mapping from
the pre-defined EARLY_IOBASE to the device I/O address passed via the
kernel parameter. The pgd entry corresponding to EARLY_IOBASE is
pre-populated in head.S during kernel boot.

Only PL011 is currently supported and it is assumed that the interface
is already initialised by the boot loader before the kernel is started.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>