This patch fix the problem with rootfs on JFFS2 with early printk
console turned on.
The origin version used TLB63 for temporary early printk mapping.
The code expect that kernel is not able to use all 64 TLB entries
till early printk console is remapped by ioremap. After that
temporary mapping on TLB63 is silently lost.
This expectation give the opportunity to have early console pretty
early.
Microblaze systems with JFFS2 rootfs with early printk console turned on
used more than 64 TLB entries before kernel can remap early console.
Based on that kernel does access to bad area because early printk mapping
is rewritten.
This patch introduces tlb_skip variable which dynamically stores number
of skipped TLB entries from the TLB0. skip_tlb=2 means that TLB0 and TLB1
should be skipped.
MICROBLAZE_TLB_SKIP defines how many TLB is skipped at the kernel start.
They can be used for user purpose.
TLB 63 is used for temporary LMB mapping (MICROBLAZE_LMB_TLB_ID).
Also clean TLBLO when kernel starts.
For specific kernel sizes kernel can use just one TLB. Detect this case
and use the second TLB for general purpose.
Change _tlbia function to flush TLB entries from tlb_skip to TLB_SIZE.
Export tlb_skip size through debugfs.
Signed-off-by: Michal Simek <monstr@monstr.eu>
Correct spelling "remaping" to "remapping" in
arch/microblaze/kernel/early_printk.c
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>
Recognize early Linux console from chosen - linux,stdout-path
instead of detecting the first console with appropriate
compatible strings.
This patch solved the problem on system with multiple
consoles.
Signed-off-by: Michal Simek <monstr@monstr.eu>
1. Register early console as standard console
2. Enable CON_BOOT console flag to ensure auto-unregistering by the kernel
3. remap_early_printk function remap physical console baseaddr to virtual space
Usage specific function for console remap is done after memory initialization
with IRQ turn off that's why there is not necessary to protect it.
The reason for remapping is that the kernel use TLB 63 for 1:1 address mapping
to be able to use console in very early boot-up phase. But allocating one TLB
just for console caused performance degression that's why ioremaps create new
mapping and TLB 63 is automatically released and ready to use.
Signed-off-by: Michal Simek <monstr@monstr.eu>
CC: Russell King <linux@arm.linux.org.uk>
CC: Ralf Baechle <ralf@linux-mips.org>
CC: Ingo Molnar <mingo@redhat.com>
CC: Alan Cox <alan@linux.intel.com>
CC: <linux-serial@vger.kernel.org>
CC: Arnd Bergmann <arnd@arndb.de>
Kconfig blocks to select any other early console support that's why
this patch has no real impact on current kernel version. But it is done
because of uart16550.
Signed-off-by: Michal Simek <monstr@monstr.eu>
retries reaches -1, so the iowrite occurrs upon timeout.
Acked-by: John Williams <john.williams@petalogix.com>
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Stephen Neuendorffer <stephen.neuendorffer@xilinx.com>
Acked-by: John Linn <john.linn@xilinx.com>
Acked-by: John Williams <john.williams@petalogix.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>
