Merge tag 'char-misc-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

Pull char / misc / IIO driver updates from Greg KH:
 "Here is the big set of char, misc, iio, and other smaller driver
  subsystems for 6.15-rc1. Lots of stuff in here, including:

   - loads of IIO changes and driver updates

   - counter driver updates

   - w1 driver updates

   - faux conversions for some drivers that were abusing the platform
     bus interface

   - coresight driver updates

   - rust miscdevice binding updates based on real-world-use

   - other minor driver updates

  All of these have been in linux-next with no reported issues for quite
  a while"

* tag 'char-misc-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (292 commits)
  samples: rust_misc_device: fix markup in top-level docs
  Coresight: Fix a NULL vs IS_ERR() bug in probe
  misc: lis3lv02d: convert to use faux_device
  tlclk: convert to use faux_device
  regulator: dummy: convert to use the faux device interface
  bus: mhi: host: Fix race between unprepare and queue_buf
  coresight: configfs: Constify struct config_item_type
  doc: iio: ad7380: describe offload support
  iio: ad7380: add support for SPI offload
  iio: light: Add check for array bounds in veml6075_read_int_time_ms
  iio: adc: ti-ads7924 Drop unnecessary function parameters
  staging: iio: ad9834: Use devm_regulator_get_enable()
  staging: iio: ad9832: Use devm_regulator_get_enable()
  iio: gyro: bmg160_spi: add of_match_table
  dt-bindings: iio: adc: Add i.MX94 and i.MX95 support
  iio: adc: ad7768-1: remove unnecessary locking
  Documentation: ABI: add wideband filter type to sysfs-bus-iio
  iio: adc: ad7768-1: set MOSI idle state to prevent accidental reset
  iio: adc: ad7768-1: Fix conversion result sign
  iio: adc: ad7124: Benefit of dev = indio_dev->dev.parent in ad7124_parse_channel_config()
  ...

2 files changed, 378 insertions, 25 deletions

diff --git a/Documentation/trace/coresight/coresight.rst b/Documentation/trace/coresight/coresight.rst
index d4f93d6a2d63..806699871b80 100644
--- a/Documentation/trace/coresight/coresight.rst
+++ b/Documentation/trace/coresight/coresight.rst
@@ -462,44 +462,35 @@ queried by the perf command line tool:
 
 		cs_etm//                                    [Kernel PMU event]
 
-	linaro@linaro-nano:~$
-
 Regardless of the number of tracers available in a system (usually equal to the
 amount of processor cores), the "cs_etm" PMU will be listed only once.
 
 A Coresight PMU works the same way as any other PMU, i.e the name of the PMU is
-listed along with configuration options within forward slashes '/'.  Since a
-Coresight system will typically have more than one sink, the name of the sink to
-work with needs to be specified as an event option.
-On newer kernels the available sinks are listed in sysFS under
+provided along with configuration options within forward slashes '/' (see
+`Config option formats`_).
+
+Advanced Perf framework usage
+-----------------------------
+
+Sink selection
+~~~~~~~~~~~~~~
+
+An appropriate sink will be selected automatically for use with Perf, but since
+there will typically be more than one sink, the name of the sink to use may be
+specified as a special config option prefixed with '@'.
+
+The available sinks are listed in sysFS under
 ($SYSFS)/bus/event_source/devices/cs_etm/sinks/::
 
 	root@localhost:/sys/bus/event_source/devices/cs_etm/sinks# ls
 	tmc_etf0  tmc_etr0  tpiu0
 
-On older kernels, this may need to be found from the list of coresight devices,
-available under ($SYSFS)/bus/coresight/devices/::
-
-	root:~# ls /sys/bus/coresight/devices/
-	 etm0     etm1     etm2         etm3  etm4      etm5      funnel0
-	 funnel1  funnel2  replicator0  stm0  tmc_etf0  tmc_etr0  tpiu0
 	root@linaro-nano:~# perf record -e cs_etm/@tmc_etr0/u --per-thread program
 
-As mentioned above in section "Device Naming scheme", the names of the devices could
-look different from what is used in the example above. One must use the device names
-as it appears under the sysFS.
-
-The syntax within the forward slashes '/' is important.  The '@' character
-tells the parser that a sink is about to be specified and that this is the sink
-to use for the trace session.
-
 More information on the above and other example on how to use Coresight with
 the perf tools can be found in the "HOWTO.md" file of the openCSD gitHub
 repository [#third]_.
 
-Advanced perf framework usage
------------------------------
-
 AutoFDO analysis using the perf tools
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -508,7 +499,7 @@ perf can be used to record and analyze trace of programs.
 Execution can be recorded using 'perf record' with the cs_etm event,
 specifying the name of the sink to record to, e.g::
 
-    perf record -e cs_etm/@tmc_etr0/u --per-thread
+    perf record -e cs_etm//u --per-thread
 
 The 'perf report' and 'perf script' commands can be used to analyze execution,
 synthesizing instruction and branch events from the instruction trace.
@@ -572,7 +563,7 @@ sort example is from the AutoFDO tutorial (https://gcc.gnu.org/wiki/AutoFDO/Tuto
 	Bubble sorting array of 30000 elements
 	5910 ms
 
-	$ perf record -e cs_etm/@tmc_etr0/u --per-thread taskset -c 2 ./sort
+	$ perf record -e cs_etm//u --per-thread taskset -c 2 ./sort
 	Bubble sorting array of 30000 elements
 	12543 ms
 	[ perf record: Woken up 35 times to write data ]
diff --git a/Documentation/trace/coresight/panic.rst b/Documentation/trace/coresight/panic.rst
new file mode 100644
index 000000000000..a58aa914c241
--- /dev/null
+++ b/Documentation/trace/coresight/panic.rst
@@ -0,0 +1,362 @@
+===================================================
+Using Coresight for Kernel panic and Watchdog reset
+===================================================
+
+Introduction
+------------
+This documentation is about using Linux coresight trace support to
+debug kernel panic and watchdog reset scenarios.
+
+Coresight trace during Kernel panic
+-----------------------------------
+From the coresight driver point of view, addressing the kernel panic
+situation has four main requirements.
+
+a. Support for allocation of trace buffer pages from reserved memory area.
+   Platform can advertise this using a new device tree property added to
+   relevant coresight nodes.
+
+b. Support for stopping coresight blocks at the time of panic
+
+c. Saving required metadata in the specified format
+
+d. Support for reading trace data captured at the time of panic
+
+Allocation of trace buffer pages from reserved RAM
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+A new optional device tree property "memory-region" is added to the
+Coresight TMC device nodes, that would give the base address and size of trace
+buffer.
+
+Static allocation of trace buffers would ensure that both IOMMU enabled
+and disabled cases are handled. Also, platforms that support persistent
+RAM will allow users to read trace data in the subsequent boot without
+booting the crashdump kernel.
+
+Note:
+For ETR sink devices, this reserved region will be used for both trace
+capture and trace data retrieval.
+For ETF sink devices, internal SRAM would be used for trace capture,
+and they would be synced to reserved region for retrieval.
+
+
+Disabling coresight blocks at the time of panic
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+In order to avoid the situation of losing relevant trace data after a
+kernel panic, it would be desirable to stop the coresight blocks at the
+time of panic.
+
+This can be achieved by configuring the comparator, CTI and sink
+devices as below::
+
+           Trigger on panic
+    Comparator --->External out --->CTI -->External In---->ETR/ETF stop
+
+Saving metadata at the time of kernel panic
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Coresight metadata involves all additional data that are required for a
+successful trace decode in addition to the trace data. This involves
+ETR/ETF/ETB register snapshot etc.
+
+A new optional device property "memory-region" is added to
+the ETR/ETF/ETB device nodes for this.
+
+Reading trace data captured at the time of panic
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Trace data captured at the time of panic, can be read from rebooted kernel
+or from crashdump kernel using a special device file /dev/crash_tmc_xxx.
+This device file is created only when there is a valid crashdata available.
+
+General flow of trace capture and decode incase of kernel panic
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+1. Enable source and sink on all the cores using the sysfs interface.
+   ETR sinks should have trace buffers allocated from reserved memory,
+   by selecting "resrv" buffer mode from sysfs.
+
+2. Run relevant tests.
+
+3. On a kernel panic, all coresight blocks are disabled, necessary
+   metadata is synced by kernel panic handler.
+
+   System would eventually reboot or boot a crashdump kernel.
+
+4. For  platforms that supports crashdump kernel, raw trace data can be
+   dumped using the coresight sysfs interface from the crashdump kernel
+   itself. Persistent RAM is not a requirement in this case.
+
+5. For platforms that supports persistent RAM, trace data can be dumped
+   using the coresight sysfs interface in the subsequent Linux boot.
+   Crashdump kernel is not a requirement in this case. Persistent RAM
+   ensures that trace data is intact across reboot.
+
+Coresight trace during Watchdog reset
+-------------------------------------
+The main difference between addressing the watchdog reset and kernel panic
+case are below,
+
+a. Saving coresight metadata need to be taken care by the
+   SCP(system control processor) firmware in the specified format,
+   instead of kernel.
+
+b. Reserved memory region given by firmware for trace buffer and metadata
+   has to be in persistent RAM.
+   Note: This is a requirement for watchdog reset case but optional
+   in kernel panic case.
+
+Watchdog reset can be supported only on platforms that meet the above
+two requirements.
+
+Sample commands for testing a Kernel panic case with ETR sink
+-------------------------------------------------------------
+
+1. Boot Linux kernel with "crash_kexec_post_notifiers" added to the kernel
+   bootargs. This is mandatory if the user would like to read the tracedata
+   from the crashdump kernel.
+
+2. Enable the preloaded ETM configuration::
+
+    #echo 1 > /sys/kernel/config/cs-syscfg/configurations/panicstop/enable
+
+3. Configure CTI using sysfs interface::
+
+    #./cti_setup.sh
+
+    #cat cti_setup.sh
+
+
+    cd /sys/bus/coresight/devices/
+
+    ap_cti_config () {
+      #ETM trig out[0] trigger to Channel 0
+      echo 0 4 > channels/trigin_attach
+    }
+
+    etf_cti_config () {
+      #ETF Flush in trigger from Channel 0
+      echo 0 1 > channels/trigout_attach
+      echo 1 > channels/trig_filter_enable
+    }
+
+    etr_cti_config () {
+      #ETR Flush in from Channel 0
+      echo 0 1 > channels/trigout_attach
+      echo 1 > channels/trig_filter_enable
+    }
+
+    ctidevs=`find . -name "cti*"`
+
+    for i in $ctidevs
+    do
+            cd $i
+
+            connection=`find . -name "ete*"`
+            if [ ! -z "$connection" ]
+            then
+                    echo "AP CTI config for $i"
+                    ap_cti_config
+            fi
+
+            connection=`find . -name "tmc_etf*"`
+            if [ ! -z "$connection" ]
+            then
+                    echo "ETF CTI config for $i"
+                    etf_cti_config
+            fi
+
+            connection=`find . -name "tmc_etr*"`
+            if [ ! -z "$connection" ]
+            then
+                    echo "ETR CTI config for $i"
+                    etr_cti_config
+            fi
+
+            cd ..
+    done
+
+Note: CTI connections are SOC specific and hence the above script is
+added just for reference.
+
+4. Choose reserved buffer mode for ETR buffer::
+
+    #echo "resrv" > /sys/bus/coresight/devices/tmc_etr0/buf_mode_preferred
+
+5. Enable stop on flush trigger configuration::
+
+    #echo 1 > /sys/bus/coresight/devices/tmc_etr0/stop_on_flush
+
+6. Start Coresight tracing on cores 1 and 2 using sysfs interface
+
+7. Run some application on core 1::
+
+    #taskset -c 1 dd if=/dev/urandom of=/dev/null &
+
+8. Invoke kernel panic on core 2::
+
+    #echo 1 > /proc/sys/kernel/panic
+    #taskset -c 2 echo c > /proc/sysrq-trigger
+
+9. From rebooted kernel or crashdump kernel, read crashdata::
+
+    #dd if=/dev/crash_tmc_etr0 of=/trace/cstrace.bin
+
+10. Run opencsd decoder tools/scripts to generate the instruction trace.
+
+Sample instruction trace dump
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Core1 dump::
+
+    A                                  etm4_enable_hw: ffff800008ae1dd4
+    CONTEXT EL2                        etm4_enable_hw: ffff800008ae1dd4
+    I                                  etm4_enable_hw: ffff800008ae1dd4:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1dd8:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1ddc:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1de0:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1de4:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1de8:
+    d503233f   paciasp
+    I                                  etm4_enable_hw: ffff800008ae1dec:
+    a9be7bfd   stp     x29, x30, [sp, #-32]!
+    I                                  etm4_enable_hw: ffff800008ae1df0:
+    910003fd   mov     x29, sp
+    I                                  etm4_enable_hw: ffff800008ae1df4:
+    a90153f3   stp     x19, x20, [sp, #16]
+    I                                  etm4_enable_hw: ffff800008ae1df8:
+    2a0003f4   mov     w20, w0
+    I                                  etm4_enable_hw: ffff800008ae1dfc:
+    900085b3   adrp    x19, ffff800009b95000 <reserved_mem+0xc48>
+    I                                  etm4_enable_hw: ffff800008ae1e00:
+    910f4273   add     x19, x19, #0x3d0
+    I                                  etm4_enable_hw: ffff800008ae1e04:
+    f8747a60   ldr     x0, [x19, x20, lsl #3]
+    E                                  etm4_enable_hw: ffff800008ae1e08:
+    b4000140   cbz     x0, ffff800008ae1e30 <etm4_starting_cpu+0x50>
+    I    149.039572921                 etm4_enable_hw: ffff800008ae1e30:
+    a94153f3   ldp     x19, x20, [sp, #16]
+    I    149.039572921                 etm4_enable_hw: ffff800008ae1e34:
+    52800000   mov     w0, #0x0                        // #0
+    I    149.039572921                 etm4_enable_hw: ffff800008ae1e38:
+    a8c27bfd   ldp     x29, x30, [sp], #32
+
+    ..snip
+
+        149.052324811           chacha_block_generic: ffff800008642d80:
+    9100a3e0   add     x0,
+    I    149.052324811           chacha_block_generic: ffff800008642d84:
+    b86178a2   ldr     w2, [x5, x1, lsl #2]
+    I    149.052324811           chacha_block_generic: ffff800008642d88:
+    8b010803   add     x3, x0, x1, lsl #2
+    I    149.052324811           chacha_block_generic: ffff800008642d8c:
+    b85fc063   ldur    w3, [x3, #-4]
+    I    149.052324811           chacha_block_generic: ffff800008642d90:
+    0b030042   add     w2, w2, w3
+    I    149.052324811           chacha_block_generic: ffff800008642d94:
+    b8217882   str     w2, [x4, x1, lsl #2]
+    I    149.052324811           chacha_block_generic: ffff800008642d98:
+    91000421   add     x1, x1, #0x1
+    I    149.052324811           chacha_block_generic: ffff800008642d9c:
+    f100443f   cmp     x1, #0x11
+
+
+Core 2 dump::
+
+    A                                  etm4_enable_hw: ffff800008ae1dd4
+    CONTEXT EL2                        etm4_enable_hw: ffff800008ae1dd4
+    I                                  etm4_enable_hw: ffff800008ae1dd4:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1dd8:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1ddc:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1de0:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1de4:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1de8:
+    d503233f   paciasp
+    I                                  etm4_enable_hw: ffff800008ae1dec:
+    a9be7bfd   stp     x29, x30, [sp, #-32]!
+    I                                  etm4_enable_hw: ffff800008ae1df0:
+    910003fd   mov     x29, sp
+    I                                  etm4_enable_hw: ffff800008ae1df4:
+    a90153f3   stp     x19, x20, [sp, #16]
+    I                                  etm4_enable_hw: ffff800008ae1df8:
+    2a0003f4   mov     w20, w0
+    I                                  etm4_enable_hw: ffff800008ae1dfc:
+    900085b3   adrp    x19, ffff800009b95000 <reserved_mem+0xc48>
+    I                                  etm4_enable_hw: ffff800008ae1e00:
+    910f4273   add     x19, x19, #0x3d0
+    I                                  etm4_enable_hw: ffff800008ae1e04:
+    f8747a60   ldr     x0, [x19, x20, lsl #3]
+    E                                  etm4_enable_hw: ffff800008ae1e08:
+    b4000140   cbz     x0, ffff800008ae1e30 <etm4_starting_cpu+0x50>
+    I    149.046243445                 etm4_enable_hw: ffff800008ae1e30:
+    a94153f3   ldp     x19, x20, [sp, #16]
+    I    149.046243445                 etm4_enable_hw: ffff800008ae1e34:
+    52800000   mov     w0, #0x0                        // #0
+    I    149.046243445                 etm4_enable_hw: ffff800008ae1e38:
+    a8c27bfd   ldp     x29, x30, [sp], #32
+    I    149.046243445                 etm4_enable_hw: ffff800008ae1e3c:
+    d50323bf   autiasp
+    E    149.046243445                 etm4_enable_hw: ffff800008ae1e40:
+    d65f03c0   ret
+    A                                ete_sysreg_write: ffff800008adfa18
+
+    ..snip
+
+    I     149.05422547                          panic: ffff800008096300:
+    a90363f7   stp     x23, x24, [sp, #48]
+    I     149.05422547                          panic: ffff800008096304:
+    6b00003f   cmp     w1, w0
+    I     149.05422547                          panic: ffff800008096308:
+    3a411804   ccmn    w0, #0x1, #0x4, ne  // ne = any
+    N     149.05422547                          panic: ffff80000809630c:
+    540001e0   b.eq    ffff800008096348 <panic+0xe0>  // b.none
+    I     149.05422547                          panic: ffff800008096310:
+    f90023f9   str     x25, [sp, #64]
+    E     149.05422547                          panic: ffff800008096314:
+    97fe44ef   bl      ffff8000080276d0 <panic_smp_self_stop>
+    A                                           panic: ffff80000809634c
+    I     149.05422547                          panic: ffff80000809634c:
+    910102d5   add     x21, x22, #0x40
+    I     149.05422547                          panic: ffff800008096350:
+    52800020   mov     w0, #0x1                        // #1
+    E     149.05422547                          panic: ffff800008096354:
+    94166b8b   bl      ffff800008631180 <bust_spinlocks>
+    N    149.054225518                 bust_spinlocks: ffff800008631180:
+    340000c0   cbz     w0, ffff800008631198 <bust_spinlocks+0x18>
+    I    149.054225518                 bust_spinlocks: ffff800008631184:
+    f000a321   adrp    x1, ffff800009a98000 <pbufs.0+0xbb8>
+    I    149.054225518                 bust_spinlocks: ffff800008631188:
+    b9405c20   ldr     w0, [x1, #92]
+    I    149.054225518                 bust_spinlocks: ffff80000863118c:
+    11000400   add     w0, w0, #0x1
+    I    149.054225518                 bust_spinlocks: ffff800008631190:
+    b9005c20   str     w0, [x1, #92]
+    E    149.054225518                 bust_spinlocks: ffff800008631194:
+    d65f03c0   ret
+    A                                           panic: ffff800008096358
+
+Perf based testing
+------------------
+
+Starting perf session
+~~~~~~~~~~~~~~~~~~~~~
+ETF::
+
+    perf record -e cs_etm/panicstop,@tmc_etf1/ -C 1
+    perf record -e cs_etm/panicstop,@tmc_etf2/ -C 2
+
+ETR::
+
+    perf record -e cs_etm/panicstop,@tmc_etr0/ -C 1,2
+
+Reading trace data after panic
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Same sysfs based method explained above can be used to retrieve and
+decode the trace data after the reboot on kernel panic.