// 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 <[email protected]>
* 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,
.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 <[email protected]>");
MODULE_DESCRIPTION("Sloppy logic analyzer using GPIOs");
MODULE_LICENSE("GPL");
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