Skip to content

Commit

Permalink
ARM: Delete ARM11MPCore (ARM11 ARMv6K SMP) support
Browse files Browse the repository at this point in the history 
This ARM11 SMP configuration was one of the first SMP configurations
the ARM kernel supported, but it has the downside of odd DMA handling,
odd cache tagging, and often (as of recent) completely broken cache
handling on the ARM RealView PB11MPCore test chips. To boot the
platform it was necessary to completely disable the cache.
When it comes to the EB 11MPCore it is unclear if this ever worked.

These reference designs are now the only ARMv6K SMP platforms.

As only reference designs of purely academic interest remain, and
since the special-cased DMA and PMU code is hard to maintain and
doesn't really work, it is not really worth our time.

Delete the ARM11MPCore support along with:

- The special DMA quirk CONFIG_DMA_CACHE_RWFO that is only used
  on ARMv6K SMP, and we are the last ARMV6K system leaving the
  building and the cache handling is awkward, so good-bye.

- The special PMU handling that was only used by ARM11MPCore.

The following is left behind:

- TIMER_OF_DECLARE(arm_twd_11mp, "arm,arm11mp-twd-timer", ...)
  in arch/arm/kernel/smp_twd.c, this is still in use by Marvell MMP3
  arch/arm/boot/dts/marvell/mmp3.dtsi

- IRQCHIP_DECLARE(arm11mp_gic, "arm,arm11mp-gic", ...)
  in drivers/irqchip/irq-gic.c, this is still in use by Marvell MMP3
  arch/arm/boot/dts/marvell/mmp3.dtsi

- A compatible for the arm11mpcore SCU, since this was mistakedly
  used for the Cortex-A9 version of RealView EB.

These are unfortunate but will need to be kept around for
compatibility. New Marvell-specific compatibles should however probably
be added.

Acked-by: Mark Rutland <[email protected]>
Reviewed-by: Arnd Bergmann <[email protected]>
Signed-off-by: Linus Walleij <[email protected]>
Acked-by: Liviu Dudau <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnd Bergmann <[email protected]>
  • Loading branch information
@linusw @arndb
linusw authored and arndb committed Dec 22, 2023
1 parent 64704ef commit 2560cff
Show file tree
Hide file tree
Showing 6 changed files with 5 additions and 102 deletions.
34 changes: 0 additions & 34 deletions arch/arm/kernel/perf_event_v6.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -525,40 +525,7 @@ static int armv6_1176_pmu_init(struct arm_pmu *cpu_pmu)
return 0;
}

/*
* ARMv6mpcore is almost identical to single core ARMv6 with the exception
* that some of the events have different enumerations and that there is no
* *hack* to stop the programmable counters. To stop the counters we simply
* disable the interrupt reporting and update the event. When unthrottling we
* reset the period and enable the interrupt reporting.
*/

static int armv6mpcore_map_event(struct perf_event *event)
{
return armpmu_map_event(event, &armv6mpcore_perf_map,
&armv6mpcore_perf_cache_map, 0xFF);
}

static int armv6mpcore_pmu_init(struct arm_pmu *cpu_pmu)
{
cpu_pmu->name = "armv6_11mpcore";
cpu_pmu->handle_irq = armv6pmu_handle_irq;
cpu_pmu->enable = armv6pmu_enable_event;
cpu_pmu->disable = armv6mpcore_pmu_disable_event;
cpu_pmu->read_counter = armv6pmu_read_counter;
cpu_pmu->write_counter = armv6pmu_write_counter;
cpu_pmu->get_event_idx = armv6pmu_get_event_idx;
cpu_pmu->clear_event_idx = armv6pmu_clear_event_idx;
cpu_pmu->start = armv6pmu_start;
cpu_pmu->stop = armv6pmu_stop;
cpu_pmu->map_event = armv6mpcore_map_event;
cpu_pmu->num_events = 3;

return 0;
}

static const struct of_device_id armv6_pmu_of_device_ids[] = {
{.compatible = "arm,arm11mpcore-pmu", .data = armv6mpcore_pmu_init},
{.compatible = "arm,arm1176-pmu", .data = armv6_1176_pmu_init},
{.compatible = "arm,arm1136-pmu", .data = armv6_1136_pmu_init},
{ /* sentinel value */ }
Expand All @@ -568,7 +535,6 @@ static const struct pmu_probe_info armv6_pmu_probe_table[] = {
ARM_PMU_PROBE(ARM_CPU_PART_ARM1136, armv6_1136_pmu_init),
ARM_PMU_PROBE(ARM_CPU_PART_ARM1156, armv6_1156_pmu_init),
ARM_PMU_PROBE(ARM_CPU_PART_ARM1176, armv6_1176_pmu_init),
ARM_PMU_PROBE(ARM_CPU_PART_ARM11MPCORE, armv6mpcore_pmu_init),
{ /* sentinel value */ }
};

Expand Down
17 changes: 0 additions & 17 deletions arch/arm/mach-versatile/Kconfig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -201,23 +201,6 @@ config REALVIEW_EB_A9MP
Enable support for the Cortex-A9MPCore tile fitted to the
Realview(R) Emulation Baseboard platform.

config REALVIEW_EB_ARM11MP
bool "Support ARM11MPCore Tile"
depends on MACH_REALVIEW_EB && ARCH_MULTI_V6
select HAVE_SMP
help
Enable support for the ARM11MPCore tile fitted to the Realview(R)
Emulation Baseboard platform.

config MACH_REALVIEW_PB11MP
bool "Support RealView(R) Platform Baseboard for ARM11MPCore"
depends on ARCH_MULTI_V6
select HAVE_SMP
help
Include support for the ARM(R) RealView(R) Platform Baseboard for
the ARM11MPCore. This platform has an on-board ARM11MPCore and has
support for PCI-E and Compact Flash.

# ARMv6 CPU without K extensions, but does have the new exclusive ops
config MACH_REALVIEW_PB1176
bool "Support RealView(R) Platform Baseboard for ARM1176JZF-S"
Expand Down
6 changes: 5 additions & 1 deletion arch/arm/mach-versatile/platsmp-realview.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,11 @@
#define REALVIEW_SYS_FLAGSSET_OFFSET 0x30

static const struct of_device_id realview_scu_match[] = {
/*
* The ARM11MP SCU compatible is only provided as fallback for
* old RealView EB Cortex-A9 device trees that were using this
* compatible by mistake.
*/
{ .compatible = "arm,arm11mp-scu", },
{ .compatible = "arm,cortex-a9-scu", },
{ .compatible = "arm,cortex-a5-scu", },
Expand All @@ -27,7 +32,6 @@ static const struct of_device_id realview_scu_match[] = {
static const struct of_device_id realview_syscon_match[] = {
{ .compatible = "arm,core-module-integrator", },
{ .compatible = "arm,realview-eb-syscon", },
{ .compatible = "arm,realview-pb11mp-syscon", },
{ .compatible = "arm,realview-pbx-syscon", },
{ },
};
Expand Down
1 change: 0 additions & 1 deletion arch/arm/mach-versatile/realview.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,6 @@
static const char *const realview_dt_platform_compat[] __initconst = {
"arm,realview-eb",
"arm,realview-pb1176",
"arm,realview-pb11mp",
"arm,realview-pba8",
"arm,realview-pbx",
NULL,
Expand Down
18 changes: 0 additions & 18 deletions arch/arm/mm/Kconfig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -937,24 +937,6 @@ config VDSO
You must have glibc 2.22 or later for programs to seamlessly
take advantage of this.

config DMA_CACHE_RWFO
bool "Enable read/write for ownership DMA cache maintenance"
depends on CPU_V6K && SMP
default y
help
The Snoop Control Unit on ARM11MPCore does not detect the
cache maintenance operations and the dma_{map,unmap}_area()
functions may leave stale cache entries on other CPUs. By
enabling this option, Read or Write For Ownership in the ARMv6
DMA cache maintenance functions is performed. These LDR/STR
instructions change the cache line state to shared or modified
so that the cache operation has the desired effect.

Note that the workaround is only valid on processors that do
not perform speculative loads into the D-cache. For such
processors, if cache maintenance operations are not broadcast
in hardware, other workarounds are needed (e.g. cache
maintenance broadcasting in software via FIQ).

config OUTER_CACHE
bool
Expand Down
31 changes: 0 additions & 31 deletions arch/arm/mm/cache-v6.S
View file
Original file line number Diff line number Diff line change
Expand Up @@ -201,10 +201,6 @@ ENTRY(v6_flush_kern_dcache_area)
* - end - virtual end address of region
*/
v6_dma_inv_range:
#ifdef CONFIG_DMA_CACHE_RWFO
ldrb r2, [r0] @ read for ownership
strb r2, [r0] @ write for ownership
#endif
tst r0, #D_CACHE_LINE_SIZE - 1
bic r0, r0, #D_CACHE_LINE_SIZE - 1
#ifdef HARVARD_CACHE
Expand All @@ -213,10 +209,6 @@ v6_dma_inv_range:
mcrne p15, 0, r0, c7, c11, 1 @ clean unified line
#endif
tst r1, #D_CACHE_LINE_SIZE - 1
#ifdef CONFIG_DMA_CACHE_RWFO
ldrbne r2, [r1, #-1] @ read for ownership
strbne r2, [r1, #-1] @ write for ownership
#endif
bic r1, r1, #D_CACHE_LINE_SIZE - 1
#ifdef HARVARD_CACHE
mcrne p15, 0, r1, c7, c14, 1 @ clean & invalidate D line
Expand All @@ -231,10 +223,6 @@ v6_dma_inv_range:
#endif
add r0, r0, #D_CACHE_LINE_SIZE
cmp r0, r1
#ifdef CONFIG_DMA_CACHE_RWFO
ldrlo r2, [r0] @ read for ownership
strlo r2, [r0] @ write for ownership
#endif
blo 1b
mov r0, #0
mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
Expand All @@ -248,9 +236,6 @@ v6_dma_inv_range:
v6_dma_clean_range:
bic r0, r0, #D_CACHE_LINE_SIZE - 1
1:
#ifdef CONFIG_DMA_CACHE_RWFO
ldr r2, [r0] @ read for ownership
#endif
#ifdef HARVARD_CACHE
mcr p15, 0, r0, c7, c10, 1 @ clean D line
#else
Expand All @@ -269,10 +254,6 @@ v6_dma_clean_range:
* - end - virtual end address of region
*/
ENTRY(v6_dma_flush_range)
#ifdef CONFIG_DMA_CACHE_RWFO
ldrb r2, [r0] @ read for ownership
strb r2, [r0] @ write for ownership
#endif
bic r0, r0, #D_CACHE_LINE_SIZE - 1
1:
#ifdef HARVARD_CACHE
Expand All @@ -282,10 +263,6 @@ ENTRY(v6_dma_flush_range)
#endif
add r0, r0, #D_CACHE_LINE_SIZE
cmp r0, r1
#ifdef CONFIG_DMA_CACHE_RWFO
ldrblo r2, [r0] @ read for ownership
strblo r2, [r0] @ write for ownership
#endif
blo 1b
mov r0, #0
mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
Expand All @@ -301,13 +278,7 @@ ENTRY(v6_dma_map_area)
add r1, r1, r0
teq r2, #DMA_FROM_DEVICE
beq v6_dma_inv_range
#ifndef CONFIG_DMA_CACHE_RWFO
b v6_dma_clean_range
#else
teq r2, #DMA_TO_DEVICE
beq v6_dma_clean_range
b v6_dma_flush_range
#endif
ENDPROC(v6_dma_map_area)

/*
Expand All @@ -317,11 +288,9 @@ ENDPROC(v6_dma_map_area)
* - dir - DMA direction
*/
ENTRY(v6_dma_unmap_area)
#ifndef CONFIG_DMA_CACHE_RWFO
add r1, r1, r0
teq r2, #DMA_TO_DEVICE
bne v6_dma_inv_range
#endif
ret lr
ENDPROC(v6_dma_unmap_area)

Expand Down

0 comments on commit 2560cff

Please sign in to comment.