u-boot.git/arch/mips/lib, branch v2018.01

MIPS: Break out of cache loops for unimplemented caches

2017-11-28T20:59:30+00:00

If we run on a CPU which doesn't implement a particular cache then we
would previously get stuck in an infinite loop, executing a cache op on
the first "line" of the missing cache & then incrementing the address by
0. This was being avoided for the L2 caches, but not for the L1s. Fix
this by generalising the check for a zero line size & avoiding the cache
op loop when this is the case.

Signed-off-by: Paul Burton 
Cc: Daniel Schwierzeck 
Cc: u-boot@lists.denx.de

MIPS: Clear instruction hazards in flush_cache()

2017-11-28T20:59:30+00:00

When writing code, for example during relocation, we ensure that the
icache has a coherent view of the new instructions with a call to
flush_cache(). This handles the bulk of the work to ensure the new
instructions will execute as expected, however it does not ensure that
the CPU pipeline doesn't already contain instructions taken from a stale
view of the affected memory. This could theoretically be a problem for
relocation, but in practice typically isn't because we sync caches for
enough code after the entry point of the newly written code that by the
time the CPU pipeline might possibly fetch any of it we'll have long ago
written it back & invalidated any stale icache entries. This is however
a problem for shorter regions of code.

In preparation for later patches which write shorter segments of code,
ensure any instruction hazards are cleared by flush_cache() by
introducing & using a new instruction_hazard_barrier() function which
makes use of the jr.hb instruction to clear the hazard.

Signed-off-by: Paul Burton 
Cc: Daniel Schwierzeck 
Cc: u-boot@lists.denx.de

MIPS: Ensure cache ops complete in cache maintenance functions

2017-11-28T20:59:30+00:00

A typical use of cache maintenance functions is to force writeback of
data which a device is about to read using DMA - for example a
descriptor or command structure. Such users of cache maintenance
functions require that operations on the cache have completed before
they proceed to instruct a device to read memory. This requires that we
place a completion barrier (ie. sync instruction) between the cache ops
and whatever write informs the device to perform DMA.

Whilst strictly speaking this isn't all users of the cache maintenance
functions & we could instead place the barriers in the drivers that
require them, it would be much more invasive to do so than to just have
the barrier be the default by placing it in the cache functions
themselves. The cost is low enough that it shouldn't matter to us in any
rare cases that we use the cache functions when not performing DMA.

Signed-off-by: Paul Burton 
Cc: Daniel Schwierzeck 
Cc: u-boot@lists.denx.de

env: Rename getenv/_f() to env_get()

2017-08-16T12:30:24+00:00

We are now using an env_ prefix for environment functions. Rename these
two functions for consistency. Also add function comments in common.h.

Quite a few places use getenv() in a condition context, provoking a
warning from checkpatch. These are fixed up in this patch also.

Suggested-by: Wolfgang Denk 
Signed-off-by: Simon Glass

MIPS: bootm: Fix broken boot_env_legacy codepath

2017-07-25T18:44:00+00:00

This patch fixes 2 bugs introduced by the following commit

2bb5b63 MIPS: bootm: rework and fix broken bootm code

The CONFIG_IS_ENABLED macro prepends 'CONFIG_' Hence, remove CONFIG_
from CONFIG_MIPS_BOOT_ENV_LEGACY usage.

Also, 2bb5b63 reworks bootm so that linux_env_legacy runs before
linux_cmdline_legacy. However, linux_env_legacy depends on
linux_cmdline_legacy running first as linux_cmdline_init initialilzes
linux_argp which linux_env_legacy later depends on during its
initialization.

Reorder the code so that linux_cmdline_legacy runs before
linux_env_legacy.

Signed-off-by: Zubair Lutfullah Kakakhel

MIPS: Stop building position independent code

2017-07-25T18:44:00+00:00

U-Boot has up until now built with -fpic for the MIPS architecture,
producing position independent code which uses indirection through a
global offset table, making relocation fairly straightforward as it
simply involves patching up GOT entries.

Using -fpic does however have some downsides. The biggest of these is
that generated code is bloated in various ways. For example, function
calls are indirected through the GOT & the t9 register:

  8f998064   lw     t9,-32668(gp)
  0320f809   jalr   t9

Without -fpic the call is simply:

  0f803f01   jal    be00fc04 

This is more compact & faster (due to the lack of the load & the
dependency the jump has on its result). It is also easier to read &
debug because the disassembly shows what function is being called,
rather than just an offset from gp which would then have to be looked up
in the ELF to discover the target function.

Another disadvantage of -fpic is that each function begins with a
sequence to calculate the value of the gp register, for example:

  3c1c0004   lui    gp,0x4
  279c3384   addiu  gp,gp,13188
  0399e021   addu   gp,gp,t9

Without using -fpic this sequence no longer appears at the start of each
function, reducing code size considerably.

This patch switches U-Boot from building with -fpic to building with
-fno-pic, in order to gain the benefits described above. The cost of
this is an extra step during the build process to extract relocation
data from the ELF & write it into a new .rel section in a compact
format, plus the added complexity of dealing with multiple types of
relocation rather than the single type that applied to the GOT. The
benefit is smaller, cleaner, more debuggable code. The relocate_code()
function is reimplemented in C to handle the new relocation scheme,
which also makes it easier to read & debug.

Taking maltael_defconfig as an example the size of u-boot.bin built
using the Codescape MIPS 2016.05-06 toolchain (gcc 4.9.2, binutils
2.24.90) shrinks from 254KiB to 224KiB.

Signed-off-by: Paul Burton 
Cc: Daniel Schwierzeck 
Cc: u-boot@lists.denx.de
Reviewed-by: Daniel Schwierzeck 
Tested-by: Daniel Schwierzeck

MIPS: Make CM GCR base configurable

2017-05-12T11:29:50+00:00

Without adding a prompt for CONFIG_MIPS_CM_BASE, Kconfig doesn't allow
defconfigs to set it. Provide the prompt in order to allow for that.

Signed-off-by: Paul Burton 
Signed-off-by: Daniel Schwierzeck 
Reviewed-by: Simon Glass

libfdt: replace ARCH_FIXUP_FDT with ARCH_FIXUP_FDT_MEMORY

2016-12-03T03:54:34+00:00

Commit e2f88dfd2d96 ("libfdt: Introduce new ARCH_FIXUP_FDT option")
allows us to skip memory setup of DTB, but a problem for ARM is that
spin_table_update_dt() and psci_update_dt() are skipped as well if
CONFIG_ARCH_FIXUP_FDT is disabled.

This commit allows us to skip only fdt_fixup_memory_banks() instead
of the whole of arch_fixup_fdt().  It will be useful when we want to
use a memory node from a kernel DTB as is, but need some fixups for
Spin-Table/PSCI.

Signed-off-by: Masahiro Yamada 
Acked-by: Alexey Brodkin 
Acked-by: Simon Glass 
Fixed build error for x86:
Signed-off-by: Simon Glass

MIPS: Use ram_top, not bi_memsize, in arch_lmb_reserve

2016-11-30T15:15:51+00:00

When calculating the region to reserve for the stack in
arch_lmb_reserve, make use of ram_top instead of adding bi_memsize to
CONFIG_SYS_SDRAM_BASE. This avoids overflow if the system has enough
memory to reach the end of the address space.

Signed-off-by: Paul Burton

MIPS: add handling for generic and EJTAG exceptions

2016-11-30T15:12:17+00:00

Add exception handlers for generic and EJTAG exceptions. Most of
the assembly code is imported from Linux kernel and adapted to U-Boot.
The exception vector table will be reserved above the stack before
U-Boot is relocated. The exception handlers will be installed and
activated after relocation in the initr_traps hook function.

Generic exceptions are handled by showing a CPU register dump similar
to Linux kernel. For example:

malta # md 1
00000001:
Ooops:
$ 0   : 00000000 00000000 00000009 00000004
$ 4   : 8ff7e108 00000000 0000003a 00000000
$ 8   : 00000008 00000001 8ff7cd18 00000004
$12   : 00000002 00000000 00000005 0000003a
$16   : 00000004 00000040 00000001 00000001
$20   : 00000000 8fff53c0 00000008 00000004
$24   : ffffffff 8ffdea44
$28   : 90001650 8ff7cd00 00000004 8ffe6818
Hi    : 00000000
Lo    : 00000004
epc   : 8ffe6848 (text bfc28848)
ra    : 8ffe6818 (text bfc28818)
Status: 00000006
Cause : 00000410 (ExcCode 04)
BadVA : 8ff9e928
PrId  : 00019300
 ### ERROR ### Please RESET the board ###

EJTAG exceptions are checked for SDBBP and delegated to the SDBBP handler
if necessary. Otherwise the debug mode will simply be exited. The SDBBP
handler currently prints the contents of registers c0_depc and c0_debug.
This could be extended in the future to handle semi-hosting according to
the MIPS UHI specification.

Signed-off-by: Daniel Schwierzeck 
Reviewed-by: Paul Burton 
Tested-by: Paul Burton