Take advantage of new libbpf feature for declarative non-autoloaded BPF
program SEC() definitions in few test that test single program at a time
out of many available programs within the single BPF object.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220419002452.632125-2-andrii@kernel.org
Establish SEC("?abc") naming convention (i.e., adding question mark in
front of otherwise normal section name) that allows to set corresponding
program's autoload property to false. This is effectively just
a declarative way to do bpf_program__set_autoload(prog, false).
Having a way to do this declaratively in BPF code itself is useful and
convenient for various scenarios. E.g., for testing, when BPF object
consists of multiple independent BPF programs that each needs to be
tested separately. Opting out all of them by default and then setting
autoload to true for just one of them at a time simplifies testing code
(see next patch for few conversions in BPF selftests taking advantage of
this new feature).
Another real-world use case is in libbpf-tools for cases when different
BPF programs have to be picked depending on particulars of the host
kernel due to various incompatible changes (like kernel function renames
or signature change, or to pick kprobe vs fentry depending on
corresponding kernel support for the latter). Marking all the different
BPF program candidates as non-autoloaded declaratively makes this more
obvious in BPF source code and allows simpler code in user-space code.
When BPF program marked as SEC("?abc") it is otherwise treated just like
SEC("abc") and bpf_program__section_name() reported will be "abc".
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220419002452.632125-1-andrii@kernel.org
Objtool's function fallthrough detection only works on C objects.
The distinction between C and assembly objects no longer makes sense
with objtool running on vmlinux.o.
Now that copy_user_64.S has been fixed up, and an objtool sibling call
detection bug has been fixed, the asm code is in "compliance" and this
hack is no longer needed. Remove it.
Fixes: ed53a0d971 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/b434cff98eca3a60dcc64c620d7d5d405a0f441c.1649718562.git.jpoimboe@redhat.com
In add_jump_destinations(), sibling call detection requires 'insn->func'
to be valid. But alternative instructions get their 'func' set in
handle_group_alt(), which runs *after* add_jump_destinations(). So
sibling calls in alternatives code don't get properly detected.
Fix that by changing the initialization order: call
add_special_section_alts() *before* add_jump_destinations().
This also means the special case for a missing 'jump_dest' in
add_jump_destinations() can be removed, as it has already been dealt
with.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/c02e0a0a2a4286b5f848d17c77fdcb7e0caf709c.1649718562.git.jpoimboe@redhat.com
For most sibling calls, 'jump_dest' is NULL because objtool treats the
jump like a call and sets 'call_dest'. But there are a few edge cases
where that's not true. Make it consistent to avoid unexpected behavior.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/8737d6b9d1691831aed73375f444f0f42da3e2c9.1649718562.git.jpoimboe@redhat.com
When a "!ENDBR" warning is reported for a data section, objtool just
prints the text address of the relocation target twice, without giving
any clues about the location of the original data reference:
vmlinux.o: warning: objtool: dcbnl_netdevice_event()+0x0: .text+0xb64680: data relocation to !ENDBR: dcbnl_netdevice_event+0x0
Instead, print the address of the data reference, in addition to the
address of the relocation target.
vmlinux.o: warning: objtool: dcbnl_nb+0x0: .data..read_mostly+0xe260: data relocation to !ENDBR: dcbnl_netdevice_event+0x0
Fixes: 89bc853eae ("objtool: Find unused ENDBR instructions")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/762e88d51300e8eaf0f933a5b0feae20ac033bea.1650300597.git.jpoimboe@redhat.com
The startup_xen() kernel entry point is referenced by the ".note.Xen"
section, and is the real entry point of the VM. Control transfer is
through IRET, which *could* set NEED_ENDBR, however Xen currently does
no such thing.
Add ANNOTATE_NOENDBR to silence future objtool warnings.
Fixes: ed53a0d971 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Link: https://lkml.kernel.org/r/a87bd48b06d11ec4b98122a429e71e489b4e48c3.1650300597.git.jpoimboe@redhat.com
The __put_user_nocheck*() inner labels are exported, so in keeping with
the "allow exported functions to be indirectly called" policy, add
ENDBR.
Fixes: ed53a0d971 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/207f02177a23031091d1a608de6049a9e5e8ff80.1650300597.git.jpoimboe@redhat.com
With IBT support in, objtool is now fully capable of following vmlinux
code flow in LTO mode. Start reporting unreachable warnings for Clang
LTO as well.
Fixes: ed53a0d971 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/7b12df54bceeb0761fe9fc8269ea0c00501214a9.1650300597.git.jpoimboe@redhat.com
Objtool can figure out that some \cfunc()s are noreturn and then
complains about certain instances having unreachable tails:
vmlinux.o: warning: objtool: asm_exc_xen_unknown_trap()+0x16: unreachable instruction
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220408094718.441854969@infradead.org
GCC-8 isn't clever enough to figure out that cpu_start_entry() is a
noreturn while objtool is. This results in code after the call in
start_secondary(). Give GCC a hand so that they all agree on things.
vmlinux.o: warning: objtool: start_secondary()+0x10e: unreachable
Reported-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220408094718.383658532@infradead.org
SYM_CODE_START*() doesn't get auto-validated and needs an UNWIND hint
to get checked, add one.
vmlinux.o: warning: objtool: pvh_start_xen()+0x0: unreachable
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220408094718.321246297@infradead.org
Apparently GCC can fail to inline a 'static inline' single caller
function:
lib/strnlen_user.o: warning: objtool: strnlen_user()+0x33: call to do_strnlen_user() with UACCESS enabled
lib/strncpy_from_user.o: warning: objtool: strncpy_from_user()+0x33: call to do_strncpy_from_user() with UACCESS enabled
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220408094718.262932488@infradead.org
A crash was observed in the ORC unwinder:
BUG: stack guard page was hit at 000000000dd984a2 (stack is 00000000d1caafca..00000000613712f0)
kernel stack overflow (page fault): 0000 [#1] SMP NOPTI
CPU: 93 PID: 23787 Comm: context_switch1 Not tainted 5.4.145 #1
RIP: 0010:unwind_next_frame
Call Trace:
<NMI>
perf_callchain_kernel
get_perf_callchain
perf_callchain
perf_prepare_sample
perf_event_output_forward
__perf_event_overflow
perf_ibs_handle_irq
perf_ibs_nmi_handler
nmi_handle
default_do_nmi
do_nmi
end_repeat_nmi
This was really two bugs:
1) The perf IBS code passed inconsistent regs to the unwinder.
2) The unwinder didn't handle the bad input gracefully.
Fix the latter bug. The ORC unwinder needs to be immune against bad
inputs. The problem is that stack_access_ok() doesn't recheck the
validity of the full range of registers after switching to the next
valid stack with get_stack_info(). Fix that.
[ jpoimboe: rewrote commit log ]
Signed-off-by: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/1650353656-956624-1-git-send-email-dmtrmonakhov@yandex-team.ru
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Drivers should not rely on the contents of this file, so
move it into the platform directory directly.
Cc: Philipp Zabel <philipp.zabel@gmail.com>
Cc: Paul Parsons <lost.distance@yahoo.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/lkml/87mudkmx8g.fsf@belgarion.home/
The drivers/pcmcia/pxa2xx_*.c are essentially part of the
board files, but for historic reasons located in drivers/pcmcia.
Move them into the same place as the actual board file to avoid
lots of machine header inclusions.
Cc: Marek Vasut <marek.vasut@gmail.com>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
The pxa2xx-ac97-lib code is the last driver to use mach/irqs.h
for PXA. Almost everything already passes the interrupt as
a resource, so use it from there.
The one exception is the mxm8x10 machine, which apparently has
a resource-less device. Replacing it with the correct one
enables the driver here as well.
Cc: alsa-devel@alsa-project.org
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Rather than relying on machine specific headers to
pass down the reboot status and the register locations,
use resources and platform_data.
Aside from this, keep the changes to a minimum.
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: linux-watchdog@vger.kernel.org
Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
From the perspective of Intel cstate residency counters,
SAPPHIRERAPIDS_X is the same as ICELAKE_X.
Share the code with it. And update the comments for SAPPHIRERAPIDS_X.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lkml.kernel.org/r/20220415104520.2737004-1-rui.zhang@intel.com
This problem can be reproduced with CONFIG_PERF_USE_VMALLOC enabled on
both x86_64 and aarch64 arch when using sysdig -B(using ebpf)[1].
sysdig -B works fine after rebuilding the kernel with
CONFIG_PERF_USE_VMALLOC disabled.
I tracked it down to the if condition event->rb->nr_pages != nr_pages
in perf_mmap is true when CONFIG_PERF_USE_VMALLOC is enabled where
event->rb->nr_pages = 1 and nr_pages = 2048 resulting perf_mmap to
return -EINVAL. This is because when CONFIG_PERF_USE_VMALLOC is
enabled, rb->nr_pages is always equal to 1.
Arch with CONFIG_PERF_USE_VMALLOC enabled by default:
arc/arm/csky/mips/sh/sparc/xtensa
Arch with CONFIG_PERF_USE_VMALLOC disabled by default:
x86_64/aarch64/...
Fix this problem by using data_page_nr()
[1] https://github.com/draios/sysdig
Fixes: 906010b213 ("perf_event: Provide vmalloc() based mmap() backing")
Signed-off-by: Zhipeng Xie <xiezhipeng1@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220209145417.6495-1-xiezhipeng1@huawei.com
The warning in cfs_rq_is_decayed() triggered:
SCHED_WARN_ON(cfs_rq->avg.load_avg ||
cfs_rq->avg.util_avg ||
cfs_rq->avg.runnable_avg)
There exists a corner case in attach_entity_load_avg() which will
cause load_sum to be zero while load_avg will not be.
Consider se_weight is 88761 as per the sched_prio_to_weight[] table.
Further assume the get_pelt_divider() is 47742, this gives:
se->avg.load_avg is 1.
However, calculating load_sum:
se->avg.load_sum = div_u64(se->avg.load_avg * se->avg.load_sum, se_weight(se));
se->avg.load_sum = 1*47742/88761 = 0.
Then enqueue_load_avg() adds this to the cfs_rq totals:
cfs_rq->avg.load_avg += se->avg.load_avg;
cfs_rq->avg.load_sum += se_weight(se) * se->avg.load_sum;
Resulting in load_avg being 1 with load_sum is 0, which will trigger
the WARN.
Fixes: f207934fb7 ("sched/fair: Align PELT windows between cfs_rq and its se")
Signed-off-by: kuyo chang <kuyo.chang@mediatek.com>
[peterz: massage changelog]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lkml.kernel.org/r/20220414090229.342-1-kuyo.chang@mediatek.com
Huge page backed vmalloc memory could benefit performance in many cases.
However, some users of vmalloc may not be ready to handle huge pages for
various reasons: hardware constraints, potential pages split, etc.
VM_NO_HUGE_VMAP was introduced to allow vmalloc users to opt-out huge
pages. However, it is not easy to track down all the users that require
the opt-out, as the allocation are passed different stacks and may cause
issues in different layers.
To address this issue, replace VM_NO_HUGE_VMAP with an opt-in flag,
VM_ALLOW_HUGE_VMAP, so that users that benefit from huge pages could ask
specificially.
Also, remove vmalloc_no_huge() and add opt-in helper vmalloc_huge().
Fixes: fac54e2bfb ("x86/Kconfig: Select HAVE_ARCH_HUGE_VMALLOC with HAVE_ARCH_HUGE_VMAP")
Link: https://lore.kernel.org/netdev/14444103-d51b-0fb3-ee63-c3f182f0b546@molgen.mpg.de/"
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Song Liu <song@kernel.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Recent changes to the firmware clock driver have not be send
to the architecture maintainers. So fix this by adding the
matching pattern.
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
There is bug in DG2 where if the CCS contexts switches out while the RCS
is running it can cause memory corruption. To workaround this add an
atomic to a memory address with a value 1 and semaphore wait to the same
address for a value of 0. The GuC firmware is responsible for writing 0
to the memory address when it is safe for the context to switch out.
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220415224025.3693037-6-umesh.nerlige.ramappa@intel.com
There are some workarounds for DG2 that are implemented in the GuC
firmware. However, the KMD is required to enable these by setting the
appropriate flag as GuC does not know what platform it is running on.
Wa_16011759253
Wa_14012630569
Wa_14013746162
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
CC: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220415224025.3693037-4-umesh.nerlige.ramappa@intel.com
Initiating a reset when the command streamer is not idle or in the
middle of executing an MI_FORCE_WAKE can result in a hang. Multiple
command streamers can be part of a single reset domain, so resetting one
would mean resetting all command streamers in that domain.
To workaround this, before initiating a reset, ensure that all command
streamers within that reset domain are either IDLE or are not executing
a MI_FORCE_WAKE.
Enable GuC PRE_PARSER WA bit so that GuC follows the WA sequence when
initiating engine-resets.
For gt-resets, ensure that i915 applies the WA sequence.
Opens to address in future patches:
- The part of the WA to wait for pending forcewakes is also applicable
to execlists backend.
- The WA also needs to be applied for gen11
Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220415224025.3693037-3-umesh.nerlige.ramappa@intel.com
Prior to doing a reset, SW must ensure command streamer is stopped,
as a workaround, to eliminate a race condition in GPM flow.
Setting both the ring stop and prefetch disable bits, will cause the
command streamer to halt.
Signed-off-by: Tilak Tangudu <tilak.tangudu@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220415224025.3693037-2-umesh.nerlige.ramappa@intel.com
The GPIO line name ETHCLK is not aligned with the other signals like
WIFI_CLK. Recently this has been fixed in the vendor tree, so upstream
this change.
Signed-off-by: Phil Elwell <phil@raspberrypi.com>
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
The convention to name not connected GPIOs with NC has never been
adapted. Also newer Raspberry Pi boards like RPi 4 never did. So fix
this inconsistency by removing all of the NC names.
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Recently this has been fixed in the vendor tree, so upstream this.
Fixes: 731b26a6ac ("ARM: bcm2835: Add names for the Raspberry Pi GPIO lines")
Signed-off-by: Phil Elwell <phil@raspberrypi.com>
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
The red LED on the Raspberry Pi 3 B Plus is the power LED.
So fix the GPIO line name accordingly.
Fixes: 71c0cd2283 ("ARM: dts: bcm2837: Add Raspberry Pi 3 B+")
Signed-off-by: Phil Elwell <phil@raspberrypi.com>
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
The GPIOs 46 & 47 are already used for a I2C interface to a SMPS.
So fix the GPIO line names accordingly.
Fixes: a54fe8a6cf ("ARM: dts: add Raspberry Pi Compute Module 3 and IO board")
Signed-off-by: Phil Elwell <phil@raspberrypi.com>
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
The GPIOs 30 to 39 are connected to the Cypress CYW43438 (Wifi/BT).
So fix the GPIO line names accordingly.
Fixes: 2c7c040c73 ("ARM: dts: bcm2835: Add Raspberry Pi Zero W")
Signed-off-by: Phil Elwell <phil@raspberrypi.com>
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
MSM8974PRO is commonly used for referring to Snapdragon 801, compared to
MSM8974 which is Snapdragon 800.
The Snapdragon 801 has three variants with different clock speeds, with
the -AA, -AB and -AC suffix.
Adjust the names in socinfo to reflect this.
Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220415195449.617040-1-luca@z3ntu.xyz
Convert the Qualcomm Shared Memory Point 2 Point bindings to DT Schema.
Changes against original bindings: enforce only specific names of child
nodes, instead of any names.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220411155528.502889-1-krzysztof.kozlowski@linaro.org
We now have geni based QUP UART controller individual binding, update
reference in parent schema and remove properties from common wrapper.
With removal of last child node schema, remove common properties of all
the controllers as they have become obsolete now.
Signed-off-by: Kuldeep Singh <singh.kuldeep87k@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220404182938.29492-5-singh.kuldeep87k@gmail.com
We now have geni based QUP I2C controller binding in place as
dt-bindigs/i2c/qcom,i2c-geni-qcom.yaml similar to other controllers,
update reference in parent schema and while at it, also remove
properties defined for the controller from common wrapper.
Signed-off-by: Kuldeep Singh <singh.kuldeep87k@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220404182938.29492-3-singh.kuldeep87k@gmail.com
Convert the Qualcomm RPMH RSC bindings to DT Schema.
Changes against original bindings:
1. Add qcom,tcs-offset as a property instead of one of reg (not used
that way).
2. Add limits to interrupts.
3. Add child nodes (bcm-voter, clock-controller, power-controller).
4. Extend the example with more complex one.
The device description and DTS examples were copied from existing
sources, so keep the license as GPL-2.0-only.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220411085935.130072-4-krzysztof.kozlowski@linaro.org
Add bindings for the AHB bus which exposes the SSC (Snapdragon Sensor Core)
block in the global address space. This bus (and the SSC block itself) is
present on certain qcom SoCs.
In typical configuration, this bus (as some of the clocks and registers
that we need to manipulate) is not accessible to Linux, and the resources
on this bus are indirectly accessed by communicating with a hexagon CPU
core residing in the SSC block. In this configuration, the hypervisor is
the one performing the bus initialization for the purposes of bringing
the hexagon CPU core out of reset.
However, it is possible to change the configuration, in which case this
driver will initialize the bus.
In combination with drivers for resources on the SSC bus, this driver can
aid in debugging, and for example with a TLMM driver can be used to
directly access SSC-dedicated GPIO pins, removing the need to commit
to a particular usecase during hw design.
Finally, until open firmware for the hexagon core is available, this
approach allows for using sensors hooked up to SSC-dedicated GPIO pins
on mainline Linux simply by utilizing the existing in-tree drivers for
these sensors.
Signed-off-by: Michael Srba <Michael.Srba@seznam.cz>
Reviewed-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220411072156.24451-5-michael.srba@seznam.cz
