new file mode 100644
@@ -0,0 +1,93 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============================================
+Linux Kernel GPIO based sloppy logic analyzer
+=============================================
+
+:Author: Wolfram Sang
+
+Introduction
+============
+
+This document briefly describes how to run the GPIO based in-kernel sloppy
+logic analyzer running on an isolated CPU.
+
+The sloppy logic analyzer will utilize a few GPIO lines in input mode on a
+system to rapidly sample these digital lines, which will, if the Nyquist
+criteria is met, result in a time series log with approximate waveforms as they
+appeared on these lines. One way to use it is to analyze external traffic
+connected to these GPIO lines with wires (i.e. digital probes), acting as a
+common logic analyzer.
+
+Another feature is to snoop on on-chip peripherals if the I/O cells of these
+peripherals can be used in GPIO input mode at the same time as they are being
+used as inputs or outputs for the peripheral. That means you could e.g. snoop
+I2C traffic without any wiring (if your hardware supports it). In the pin
+control subsystem such pin controllers are called "non-strict": a certain pin
+can be used with a certain peripheral and as a GPIO input line at the same
+time.
+
+Note that this is a last resort analyzer which can be affected by latencies,
+non-deterministic code paths and non-maskable interrupts. It is called 'sloppy'
+for a reason. However, for e.g. remote development, it may be useful to get a
+first view and aid further debugging.
+
+Setup
+=====
+
+Your kernel must have CONFIG_DEBUG_FS and CONFIG_CPUSETS enabled. Ideally, your
+runtime environment does not utilize cpusets otherwise, then isolation of a CPU
+core is easiest. If you do need cpusets, check that helper script for the
+sloppy logic analyzer does not interfere with your other settings.
+
+Tell the kernel which GPIOs are used as probes. For a Device Tree based system,
+you need to use the following bindings. Because these bindings are only for
+debugging, there is no official schema::
+
+ i2c-analyzer {
+ compatible = "gpio-sloppy-logic-analyzer";
+ probe-gpios = <&gpio6 21 GPIO_OPEN_DRAIN>, <&gpio6 4 GPIO_OPEN_DRAIN>;
+ probe-names = "SCL", "SDA";
+ };
+
+Note that you must provide a name for every GPIO specified. Currently a
+maximum of 8 probes are supported. 32 are likely possible but are not
+implemented yet.
+
+Usage
+=====
+
+The logic analyzer is configurable via files in debugfs. However, it is
+strongly recommended to not use them directly, but to use the script
+``tools/gpio/gpio-sloppy-logic-analyzer``. Besides checking parameters more
+extensively, it will isolate the CPU core so you will have the least
+disturbance while measuring.
+
+The script has a help option explaining the parameters. For the above DT
+snippet which analyzes an I2C bus at 400kHz on a Renesas Salvator-XS board, the
+following settings are used: The isolated CPU shall be CPU1 because it is a big
+core in a big.LITTLE setup. Because CPU1 is the default, we don't need a
+parameter. The bus speed is 400kHz. So, the sampling theorem says we need to
+sample at least at 800kHz. However, falling edges of both signals in an I2C
+start condition happen faster, so we need a higher sampling frequency, e.g.
+``-s 1500000`` for 1.5MHz. Also, we don't want to sample right away but wait
+for a start condition on an idle bus. So, we need to set a trigger to a falling
+edge on SDA while SCL stays high, i.e. ``-t 1H+2F``. Last is the duration, let
+us assume 15ms here which results in the parameter ``-d 15000``. So,
+altogether::
+
+ gpio-sloppy-logic-analyzer -s 1500000 -t 1H+2F -d 15000
+
+Note that the process will return you back to the prompt but a sub-process is
+still sampling in the background. Unless this has finished, you will not find a
+result file in the current or specified directory. For the above example, we
+will then need to trigger I2C communication::
+
+ i2cdetect -y -r <your bus number>
+
+Result is a .sr file to be consumed with PulseView or sigrok-cli from the free
+`sigrok`_ project. It is a zip file which also contains the binary sample data
+which may be consumed by other software. The filename is the logic analyzer
+instance name plus a since-epoch timestamp.
+
+.. _sigrok: https://sigrok.org/
@@ -32,6 +32,7 @@ Documentation/dev-tools/testing-overview.rst
kunit/index
ktap
checkuapi
+ gpio-sloppy-logic-analyzer
.. only:: subproject and html
@@ -1891,4 +1891,21 @@ config GPIO_SIM
endmenu
+menu "GPIO hardware hacking tools"
+
+config GPIO_SLOPPY_LOGIC_ANALYZER
+ tristate "Sloppy GPIO logic analyzer"
+ depends on (GPIOLIB || COMPILE_TEST) && CPUSETS && DEBUG_FS && EXPERT
+ help
+ This option enables support for a sloppy logic analyzer using polled
+ GPIOs. Use the 'tools/gpio/gpio-sloppy-logic-analyzer' script with
+ this driver. The script will make it easier to use and will also
+ isolate a CPU for the polling task. Note that this is a last resort
+ analyzer which can be affected by latencies, non-deterministic code
+ paths, or NMIs. However, for e.g. remote development, it may be useful
+ to get a first view and aid further debugging.
+
+ If this driver is built as a module it will be called
+ 'gpio-sloppy-logic-analyzer'.
+endmenu
endif
@@ -150,6 +150,7 @@ obj-$(CONFIG_GPIO_SIFIVE) += gpio-sifive.o
obj-$(CONFIG_GPIO_SIM) += gpio-sim.o
obj-$(CONFIG_GPIO_SIOX) += gpio-siox.o
obj-$(CONFIG_GPIO_SL28CPLD) += gpio-sl28cpld.o
+obj-$(CONFIG_GPIO_SLOPPY_LOGIC_ANALYZER) += gpio-sloppy-logic-analyzer.o
obj-$(CONFIG_GPIO_SODAVILLE) += gpio-sodaville.o
obj-$(CONFIG_GPIO_SPEAR_SPICS) += gpio-spear-spics.o
obj-$(CONFIG_GPIO_SPRD) += gpio-sprd.o
new file mode 100644
@@ -0,0 +1,344 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Sloppy logic analyzer using GPIOs (to be run on an isolated CPU)
+ *
+ * Use the 'gpio-sloppy-logic-analyzer' script in the 'tools/gpio' folder for
+ * easier usage and further documentation. Note that this is a last resort
+ * analyzer which can be affected by latencies and non-deterministic code
+ * paths. However, for e.g. remote development, it may be useful to get a first
+ * view and aid further debugging.
+ *
+ * Copyright (C) Wolfram Sang <wsa@sang-engineering.com>
+ * Copyright (C) Renesas Electronics Corporation
+ */
+
+#include <linux/ctype.h>
+#include <linux/debugfs.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/init.h>
+#include <linux/ktime.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+#include <linux/sizes.h>
+#include <linux/timekeeping.h>
+#include <linux/types.h>
+#include <linux/vmalloc.h>
+
+#define GPIO_LA_NAME "gpio-sloppy-logic-analyzer"
+#define GPIO_LA_DEFAULT_BUF_SIZE SZ_256K
+/* can be increased but then we need to extend the u8 buffers */
+#define GPIO_LA_MAX_PROBES 8
+#define GPIO_LA_NUM_TESTS 1024
+
+struct gpio_la_poll_priv {
+ struct mutex blob_lock; /* serialize access to the blob (data) */
+ u32 buf_idx;
+ struct gpio_descs *descs;
+ unsigned long delay_ns;
+ unsigned long acq_delay;
+ struct debugfs_blob_wrapper blob;
+ struct dentry *debug_dir;
+ struct dentry *blob_dent;
+ struct debugfs_blob_wrapper meta;
+ struct device *dev;
+ unsigned int trig_len;
+ u8 *trig_data;
+};
+
+static struct dentry *gpio_la_poll_debug_dir;
+
+static __always_inline int gpio_la_get_array(struct gpio_descs *d, unsigned long *sptr)
+{
+ int ret;
+
+ ret = gpiod_get_array_value(d->ndescs, d->desc, d->info, sptr);
+ if (ret == 0 && fatal_signal_pending(current))
+ ret = -EINTR;
+
+ return ret;
+}
+
+static int fops_capture_set(void *data, u64 val)
+{
+ struct gpio_la_poll_priv *priv = data;
+ u8 *la_buf = priv->blob.data;
+ unsigned long state = 0; /* zeroed because GPIO arrays are bitfields */
+ unsigned long delay;
+ ktime_t start_time;
+ unsigned int i;
+ int ret;
+
+ if (!val)
+ return 0;
+
+ if (!la_buf)
+ return -ENOMEM;
+
+ if (!priv->delay_ns)
+ return -EINVAL;
+
+ mutex_lock(&priv->blob_lock);
+ if (priv->blob_dent) {
+ debugfs_remove(priv->blob_dent);
+ priv->blob_dent = NULL;
+ }
+
+ priv->buf_idx = 0;
+
+ local_irq_disable();
+ preempt_disable_notrace();
+
+ /* Measure delay of reading GPIOs */
+ start_time = ktime_get();
+ for (i = 0; i < GPIO_LA_NUM_TESTS; i++) {
+ ret = gpio_la_get_array(priv->descs, &state);
+ if (ret)
+ goto out;
+ }
+
+ priv->acq_delay = ktime_sub(ktime_get(), start_time) / GPIO_LA_NUM_TESTS;
+ if (priv->delay_ns < priv->acq_delay) {
+ ret = -ERANGE;
+ goto out;
+ }
+
+ delay = priv->delay_ns - priv->acq_delay;
+
+ /* Wait for triggers */
+ for (i = 0; i < priv->trig_len; i += 2) {
+ do {
+ ret = gpio_la_get_array(priv->descs, &state);
+ if (ret)
+ goto out;
+
+ ndelay(delay);
+ } while ((state & priv->trig_data[i]) != priv->trig_data[i + 1]);
+ }
+
+ /* With triggers, final state is also the first sample */
+ if (priv->trig_len)
+ la_buf[priv->buf_idx++] = state;
+
+ /* Sample */
+ while (priv->buf_idx < priv->blob.size) {
+ ret = gpio_la_get_array(priv->descs, &state);
+ if (ret)
+ goto out;
+
+ la_buf[priv->buf_idx++] = state;
+ ndelay(delay);
+ }
+out:
+ preempt_enable_notrace();
+ local_irq_enable();
+ if (ret)
+ dev_err(priv->dev, "couldn't read GPIOs: %d\n", ret);
+
+ kfree(priv->trig_data);
+ priv->trig_data = NULL;
+ priv->trig_len = 0;
+
+ priv->blob_dent = debugfs_create_blob("sample_data", 0400, priv->debug_dir, &priv->blob);
+ mutex_unlock(&priv->blob_lock);
+
+ return ret;
+}
+DEFINE_DEBUGFS_ATTRIBUTE(fops_capture, NULL, fops_capture_set, "%llu\n");
+
+static int fops_buf_size_get(void *data, u64 *val)
+{
+ struct gpio_la_poll_priv *priv = data;
+
+ *val = priv->blob.size;
+
+ return 0;
+}
+
+static int fops_buf_size_set(void *data, u64 val)
+{
+ struct gpio_la_poll_priv *priv = data;
+ int ret = 0;
+ void *p;
+
+ if (!val)
+ return -EINVAL;
+
+ mutex_lock(&priv->blob_lock);
+
+ vfree(priv->blob.data);
+ p = vzalloc(val);
+ if (!p) {
+ val = 0;
+ ret = -ENOMEM;
+ }
+
+ priv->blob.data = p;
+ priv->blob.size = val;
+
+ mutex_unlock(&priv->blob_lock);
+ return ret;
+}
+DEFINE_DEBUGFS_ATTRIBUTE(fops_buf_size, fops_buf_size_get, fops_buf_size_set, "%llu\n");
+
+static int trigger_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, NULL, inode->i_private);
+}
+
+static ssize_t trigger_write(struct file *file, const char __user *ubuf,
+ size_t count, loff_t *offset)
+{
+ struct seq_file *m = file->private_data;
+ struct gpio_la_poll_priv *priv = m->private;
+ char *buf;
+
+ /* upper limit is arbitrary but should be less than PAGE_SIZE */
+ if (count > 2048 || count & 1)
+ return -EINVAL;
+
+ buf = memdup_user(ubuf, count);
+ if (IS_ERR(buf))
+ return PTR_ERR(buf);
+
+ priv->trig_data = buf;
+ priv->trig_len = count;
+
+ return count;
+}
+
+static const struct file_operations fops_trigger = {
+ .owner = THIS_MODULE,
+ .open = trigger_open,
+ .write = trigger_write,
+ .llseek = no_llseek,
+ .release = single_release,
+};
+
+static int gpio_la_poll_probe(struct platform_device *pdev)
+{
+ struct gpio_la_poll_priv *priv;
+ struct device *dev = &pdev->dev;
+ const char *devname = dev_name(dev);
+ const char *gpio_names[GPIO_LA_MAX_PROBES];
+ char *meta = NULL;
+ unsigned int i, meta_len = 0;
+ int ret;
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ devm_mutex_init(dev, &priv->blob_lock);
+
+ fops_buf_size_set(priv, GPIO_LA_DEFAULT_BUF_SIZE);
+
+ priv->descs = devm_gpiod_get_array(dev, "probe", GPIOD_IN);
+ if (IS_ERR(priv->descs))
+ return PTR_ERR(priv->descs);
+
+ /* artificial limit to keep 1 byte per sample for now */
+ if (priv->descs->ndescs > GPIO_LA_MAX_PROBES)
+ return -EFBIG;
+
+ ret = device_property_read_string_array(dev, "probe-names", gpio_names,
+ priv->descs->ndescs);
+ if (ret >= 0 && ret != priv->descs->ndescs)
+ ret = -EBADR;
+ if (ret < 0)
+ return dev_err_probe(dev, ret, "error naming the GPIOs");
+
+ for (i = 0; i < priv->descs->ndescs; i++) {
+ unsigned int add_len;
+ char *new_meta, *consumer_name;
+
+ if (gpiod_cansleep(priv->descs->desc[i]))
+ return -EREMOTE;
+
+ consumer_name = kasprintf(GFP_KERNEL, "%s: %s", devname, gpio_names[i]);
+ if (!consumer_name)
+ return -ENOMEM;
+ gpiod_set_consumer_name(priv->descs->desc[i], consumer_name);
+ kfree(consumer_name);
+
+ /* '10' is length of 'probe00=\n\0' */
+ add_len = strlen(gpio_names[i]) + 10;
+
+ new_meta = devm_krealloc(dev, meta, meta_len + add_len, GFP_KERNEL);
+ if (!new_meta)
+ return -ENOMEM;
+
+ meta = new_meta;
+ meta_len += snprintf(meta + meta_len, add_len, "probe%02u=%s\n",
+ i + 1, gpio_names[i]);
+ }
+
+ platform_set_drvdata(pdev, priv);
+ priv->dev = dev;
+
+ priv->meta.data = meta;
+ priv->meta.size = meta_len;
+ priv->debug_dir = debugfs_create_dir(devname, gpio_la_poll_debug_dir);
+ debugfs_create_blob("meta_data", 0400, priv->debug_dir, &priv->meta);
+ debugfs_create_ulong("delay_ns", 0600, priv->debug_dir, &priv->delay_ns);
+ debugfs_create_ulong("delay_ns_acquisition", 0400, priv->debug_dir, &priv->acq_delay);
+ debugfs_create_file_unsafe("buf_size", 0600, priv->debug_dir, priv, &fops_buf_size);
+ debugfs_create_file_unsafe("capture", 0200, priv->debug_dir, priv, &fops_capture);
+ debugfs_create_file_unsafe("trigger", 0200, priv->debug_dir, priv, &fops_trigger);
+
+ return 0;
+}
+
+static void gpio_la_poll_remove(struct platform_device *pdev)
+{
+ struct gpio_la_poll_priv *priv = platform_get_drvdata(pdev);
+
+ mutex_lock(&priv->blob_lock);
+ debugfs_remove_recursive(priv->debug_dir);
+ mutex_unlock(&priv->blob_lock);
+}
+
+static const struct of_device_id gpio_la_poll_of_match[] = {
+ { .compatible = GPIO_LA_NAME },
+ { }
+};
+MODULE_DEVICE_TABLE(of, gpio_la_poll_of_match);
+
+static struct platform_driver gpio_la_poll_device_driver = {
+ .probe = gpio_la_poll_probe,
+ .remove_new = gpio_la_poll_remove,
+ .driver = {
+ .name = GPIO_LA_NAME,
+ .of_match_table = gpio_la_poll_of_match,
+ }
+};
+
+static int __init gpio_la_poll_init(void)
+{
+ gpio_la_poll_debug_dir = debugfs_create_dir(GPIO_LA_NAME, NULL);
+
+ return platform_driver_register(&gpio_la_poll_device_driver);
+}
+/*
+ * Non-strict pin controllers can read GPIOs while being muxed to something else.
+ * To support that, we need to claim GPIOs before further pinmuxing happens. So,
+ * we probe early using 'late_initcall'
+ */
+late_initcall(gpio_la_poll_init);
+
+static void __exit gpio_la_poll_exit(void)
+{
+ platform_driver_unregister(&gpio_la_poll_device_driver);
+ debugfs_remove_recursive(gpio_la_poll_debug_dir);
+}
+module_exit(gpio_la_poll_exit);
+
+MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
+MODULE_DESCRIPTION("Sloppy logic analyzer using GPIOs");
+MODULE_LICENSE("GPL");
new file mode 100755
@@ -0,0 +1,246 @@
+#!/bin/sh -eu
+# SPDX-License-Identifier: GPL-2.0
+#
+# Helper script for the Linux Kernel GPIO sloppy logic analyzer
+#
+# Copyright (C) Wolfram Sang <wsa@sang-engineering.com>
+# Copyright (C) Renesas Electronics Corporation
+
+samplefreq=1000000
+numsamples=250000
+cpusetdefaultdir='/sys/fs/cgroup'
+cpusetprefix='cpuset.'
+debugdir='/sys/kernel/debug'
+ladirname='gpio-sloppy-logic-analyzer'
+outputdir="$PWD"
+neededcmds='taskset zip'
+max_chans=8
+duration=
+initcpu=
+listinstances=0
+lainstance=
+lasysfsdir=
+triggerdat=
+trigger_bindat=
+progname="${0##*/}"
+print_help()
+{
+ cat << EOF
+$progname - helper script for the Linux Kernel Sloppy GPIO Logic Analyzer
+Available options:
+ -c|--cpu <n>: which CPU to isolate for sampling. Only needed once. Default <1>.
+ Remember that a more powerful CPU gives you higher sampling speeds.
+ Also CPU0 is not recommended as it usually does extra bookkeeping.
+ -d|--duration-us <SI-n>: number of microseconds to sample. Overrides -n, no default value.
+ -h|--help: print this help
+ -i|--instance <str>: name of the logic analyzer in case you have multiple instances. Default
+ to first instance found
+ -k|--kernel-debug-dir <str>: path to the kernel debugfs mountpoint. Default: <$debugdir>
+ -l|--list-instances: list all available instances
+ -n|--num_samples <SI-n>: number of samples to acquire. Default <$numsamples>
+ -o|--output-dir <str>: directory to put the result files. Default: current dir
+ -s|--sample_freq <SI-n>: desired sampling frequency. Might be capped if too large.
+ Default: <1000000>
+ -t|--trigger <str>: pattern to use as trigger. <str> consists of two-char pairs. First
+ char is channel number starting at "1". Second char is trigger level:
+ "L" - low; "H" - high; "R" - rising; "F" - falling
+ These pairs can be combined with "+", so "1H+2F" triggers when probe 1
+ is high while probe 2 has a falling edge. You can have multiple triggers
+ combined with ",". So, "1H+2F,1H+2R" is like the example before but it
+ waits for a rising edge on probe 2 while probe 1 is still high after the
+ first trigger has been met.
+ Trigger data will only be used for the next capture and then be erased.
+
+<SI-n> is an integer value where SI units "T", "G", "M", "K" are recognized, e.g. '1M500K' is 1500000.
+
+Examples:
+Samples $numsamples values at 1MHz with an already prepared CPU or automatically prepares CPU1 if needed,
+use the first logic analyzer instance found:
+ '$progname'
+Samples 50us at 2MHz waiting for a falling edge on channel 2. CPU and instance as above:
+ '$progname -d 50 -s 2M -t "2F"'
+
+Note that the process exits after checking all parameters but a sub-process still works in
+the background. The result is only available once the sub-process finishes.
+
+Result is a .sr file to be consumed with PulseView from the free Sigrok project. It is
+a zip file which also contains the binary sample data which may be consumed by others.
+The filename is the logic analyzer instance name plus a since-epoch timestamp.
+EOF
+}
+
+fail()
+{
+ echo "$1"
+ exit 1
+}
+
+parse_si()
+{
+ conv_si="$(printf $1 | sed 's/[tT]+\?/*1000G+/g; s/[gG]+\?/*1000M+/g; s/[mM]+\?/*1000K+/g; s/[kK]+\?/*1000+/g; s/+$//')"
+ si_val="$((conv_si))"
+}
+set_newmask()
+{
+ for f in $(find "$1" -iname "$2"); do echo "$newmask" > "$f" 2>/dev/null || true; done
+}
+
+init_cpu()
+{
+ isol_cpu="$1"
+
+ [ -d "$lacpusetdir" ] || mkdir "$lacpusetdir"
+
+ cur_cpu=$(cat "${lacpusetfile}cpus")
+ [ "$cur_cpu" = "$isol_cpu" ] && return
+ [ -z "$cur_cpu" ] || fail "CPU$isol_cpu requested but CPU$cur_cpu already isolated"
+
+ echo "$isol_cpu" > "${lacpusetfile}cpus" || fail "Could not isolate CPU$isol_cpu. Does it exist?"
+ echo 1 > "${lacpusetfile}cpu_exclusive"
+ echo 0 > "${lacpusetfile}mems"
+
+ oldmask=$(cat /proc/irq/default_smp_affinity)
+ newmask=$(printf "%x" $((0x$oldmask & ~(1 << isol_cpu))))
+
+ set_newmask '/proc/irq' '*smp_affinity'
+ set_newmask '/sys/devices/virtual/workqueue/' 'cpumask'
+
+ # Move tasks away from isolated CPU
+ for p in $(ps -o pid | tail -n +2); do
+ mask=$(taskset -p "$p") || continue
+ # Ignore tasks with a custom mask, i.e. not equal $oldmask
+ [ "${mask##*: }" = "$oldmask" ] || continue
+ taskset -p "$newmask" "$p" || continue
+ done 2>/dev/null >/dev/null
+
+ # Big hammer! Working with 'rcu_momentary_dyntick_idle()' for a more fine-grained solution
+ # still printed warnings. Same for re-enabling the stall detector after sampling.
+ echo 1 > /sys/module/rcupdate/parameters/rcu_cpu_stall_suppress
+
+ cpufreqgov="/sys/devices/system/cpu/cpu$isol_cpu/cpufreq/scaling_governor"
+ [ -w "$cpufreqgov" ] && echo 'performance' > "$cpufreqgov" || true
+}
+
+parse_triggerdat()
+{
+ oldifs="$IFS"
+ IFS=','; for trig in $1; do
+ mask=0; val1=0; val2=0
+ IFS='+'; for elem in $trig; do
+ chan=${elem%[lhfrLHFR]}
+ mode=${elem#$chan}
+ # Check if we could parse something and the channel number fits
+ [ "$chan" != "$elem" ] && [ "$chan" -le $max_chans ] || fail "Trigger syntax error: $elem"
+ bit=$((1 << (chan - 1)))
+ mask=$((mask | bit))
+ case $mode in
+ [hH]) val1=$((val1 | bit)); val2=$((val2 | bit));;
+ [fF]) val1=$((val1 | bit));;
+ [rR]) val2=$((val2 | bit));;
+ esac
+ done
+ trigger_bindat="$trigger_bindat$(printf '\\%o\\%o' $mask $val1)"
+ [ $val1 -ne $val2 ] && trigger_bindat="$trigger_bindat$(printf '\\%o\\%o' $mask $val2)"
+ done
+ IFS="$oldifs"
+}
+
+do_capture()
+{
+ taskset "$1" echo 1 > "$lasysfsdir"/capture || fail "Capture error! Check kernel log"
+
+ srtmp=$(mktemp -d)
+ echo 1 > "$srtmp"/version
+ cp "$lasysfsdir"/sample_data "$srtmp"/logic-1-1
+ cat > "$srtmp"/metadata << EOF
+[global]
+sigrok version=0.2.0
+
+[device 1]
+capturefile=logic-1
+total probes=$(wc -l < "$lasysfsdir"/meta_data)
+samplerate=${samplefreq}Hz
+unitsize=1
+EOF
+ cat "$lasysfsdir"/meta_data >> "$srtmp"/metadata
+
+ zipname="$outputdir/${lasysfsdir##*/}-$(date +%s).sr"
+ zip -jq "$zipname" "$srtmp"/*
+ rm -rf "$srtmp"
+ delay_ack=$(cat "$lasysfsdir"/delay_ns_acquisition)
+ [ "$delay_ack" -eq 0 ] && delay_ack=1
+ echo "Logic analyzer done. Saved '$zipname'"
+ echo "Max sample frequency this time: $((1000000000 / delay_ack))Hz."
+}
+
+rep=$(getopt -a -l cpu:,duration-us:,help,instance:,list-instances,kernel-debug-dir:,num_samples:,output-dir:,sample_freq:,trigger: -o c:d:hi:k:ln:o:s:t: -- "$@") || exit 1
+eval set -- "$rep"
+while true; do
+ case "$1" in
+ -c|--cpu) initcpu="$2"; shift;;
+ -d|--duration-us) parse_si $2; duration=$si_val; shift;;
+ -h|--help) print_help; exit 0;;
+ -i|--instance) lainstance="$2"; shift;;
+ -k|--kernel-debug-dir) debugdir="$2"; shift;;
+ -l|--list-instances) listinstances=1;;
+ -n|--num_samples) parse_si $2; numsamples=$si_val; shift;;
+ -o|--output-dir) outputdir="$2"; shift;;
+ -s|--sample_freq) parse_si $2; samplefreq=$si_val; shift;;
+ -t|--trigger) triggerdat="$2"; shift;;
+ --) break;;
+ *) fail "error parsing command line: $*";;
+ esac
+ shift
+done
+
+for f in $neededcmds; do
+ command -v "$f" >/dev/null || fail "Command '$f' not found"
+done
+
+# print cpuset mountpoint if any, errorcode > 0 if noprefix option was found
+cpusetdir=$(awk '$3 == "cgroup" && $4 ~ /cpuset/ { print $2; exit (match($4, /noprefix/) > 0) }' /proc/self/mounts) || cpusetprefix=''
+if [ -z "$cpusetdir" ]; then
+ cpusetdir="$cpusetdefaultdir"
+ [ -d $cpusetdir ] || mkdir $cpusetdir
+ mount -t cgroup -o cpuset none $cpusetdir || fail "Couldn't mount cpusets. Not in kernel or already in use?"
+fi
+
+lacpusetdir="$cpusetdir/$ladirname"
+lacpusetfile="$lacpusetdir/$cpusetprefix"
+sysfsdir="$debugdir/$ladirname"
+
+[ "$samplefreq" -ne 0 ] || fail "Invalid sample frequency"
+
+[ -d "$sysfsdir" ] || fail "Could not find logic analyzer root dir '$sysfsdir'. Module loaded?"
+[ -x "$sysfsdir" ] || fail "Could not access logic analyzer root dir '$sysfsdir'. Need root?"
+
+[ $listinstances -gt 0 ] && find "$sysfsdir" -mindepth 1 -type d | sed 's|.*/||' && exit 0
+
+if [ -n "$lainstance" ]; then
+ lasysfsdir="$sysfsdir/$lainstance"
+else
+ lasysfsdir=$(find "$sysfsdir" -mindepth 1 -type d -print -quit)
+fi
+[ -d "$lasysfsdir" ] || fail "Logic analyzer directory '$lasysfsdir' not found!"
+[ -d "$outputdir" ] || fail "Output directory '$outputdir' not found!"
+
+[ -n "$initcpu" ] && init_cpu "$initcpu"
+[ -d "$lacpusetdir" ] || { echo "Auto-Isolating CPU1"; init_cpu 1; }
+
+ndelay=$((1000000000 / samplefreq))
+echo "$ndelay" > "$lasysfsdir"/delay_ns
+
+[ -n "$duration" ] && numsamples=$((samplefreq * duration / 1000000))
+echo $numsamples > "$lasysfsdir"/buf_size
+
+if [ -n "$triggerdat" ]; then
+ parse_triggerdat "$triggerdat"
+ printf "$trigger_bindat" > "$lasysfsdir"/trigger 2>/dev/null || fail "Trigger data '$triggerdat' rejected"
+fi
+
+workcpu=$(cat "${lacpusetfile}effective_cpus")
+[ -n "$workcpu" ] || fail "No isolated CPU found"
+cpumask=$(printf '%x' $((1 << workcpu)))
+instance=${lasysfsdir##*/}
+echo "Setting up '$instance': $numsamples samples at ${samplefreq}Hz with ${triggerdat:-no} trigger using CPU$workcpu"
+do_capture "$cpumask" &
This is a sloppy logic analyzer using GPIOs. It comes with a script to isolate a CPU for polling. While this is definitely not a production level analyzer, it can be a helpful first view when remote debugging. Read the documentation for details. Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> --- .../dev-tools/gpio-sloppy-logic-analyzer.rst | 93 +++++ Documentation/dev-tools/index.rst | 1 + drivers/gpio/Kconfig | 17 + drivers/gpio/Makefile | 1 + drivers/gpio/gpio-sloppy-logic-analyzer.c | 344 ++++++++++++++++++ tools/gpio/gpio-sloppy-logic-analyzer.sh | 246 +++++++++++++ 6 files changed, 702 insertions(+) create mode 100644 Documentation/dev-tools/gpio-sloppy-logic-analyzer.rst create mode 100644 drivers/gpio/gpio-sloppy-logic-analyzer.c create mode 100755 tools/gpio/gpio-sloppy-logic-analyzer.sh