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staging: axis-fifo: add debugfs interface for dumping fifo registers

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For debugging purposes, add a simple, read-only debugfs interface to dump
the following fifo registers:
ISR  - Interrupt Status Register
IER  - Interrupt Enable Register
TDFV - Transmit Data FIFO Vacancy
RDFO - Receive Data FIFO Occupancy

$ cat /sys/kernel/debug/43c00000.axi_fifo_mm_s/regs
 isr: 0x00000000
 ier: 0xfe000000
tdfv: 0x000001fc
rdfo: 0x00000000

Signed-off-by: Ovidiu Panait <ovidiu.panait.oss@gmail.com>
Link: https://lore.kernel.org/r/20250720183833.3570345-2-ovidiu.panait.oss@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ovidiu Panait
2025-07-20 21:38:33 +03:00
committed by Greg Kroah-Hartman
parent ff9ec95102
commit fe4e81979a
1 changed files with 44 additions and 0 deletions
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44
drivers/staging/axis-fifo/axis-fifo.c
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@@ -33,6 +33,7 @@
#include <linux/uaccess.h>
#include <linux/jiffies.h>
#include <linux/miscdevice.h>
#include <linux/debugfs.h>
/* ----------------------------
* driver parameters
@@ -44,6 +45,8 @@
#define READ_BUF_SIZE 128U /* read buffer length in words */
#define WRITE_BUF_SIZE 128U /* write buffer length in words */
#define AXIS_FIFO_DEBUG_REG_NAME_MAX_LEN 4
/* ----------------------------
* IP register offsets
* ----------------------------
@@ -137,6 +140,13 @@ struct axis_fifo {
struct device *dt_device; /* device created from the device tree */
struct miscdevice miscdev;
struct dentry *debugfs_dir;
};
struct axis_fifo_debug_reg {
const char * const name;
unsigned int offset;
};
/* ----------------------------
@@ -537,6 +547,37 @@ static const struct file_operations fops = {
.write = axis_fifo_write
};
static int axis_fifo_debugfs_regs_show(struct seq_file *m, void *p)
{
static const struct axis_fifo_debug_reg regs[] = {
{"isr", XLLF_ISR_OFFSET},
{"ier", XLLF_IER_OFFSET},
{"tdfv", XLLF_TDFV_OFFSET},
{"rdfo", XLLF_RDFO_OFFSET},
{ /* Sentinel */ },
};
const struct axis_fifo_debug_reg *reg;
struct axis_fifo *fifo = m->private;
for (reg = regs; reg->name; ++reg) {
u32 val = ioread32(fifo->base_addr + reg->offset);
seq_printf(m, "%*s: 0x%08x\n", AXIS_FIFO_DEBUG_REG_NAME_MAX_LEN,
reg->name, val);
}
return 0;
}
DEFINE_SHOW_ATTRIBUTE(axis_fifo_debugfs_regs);
static void axis_fifo_debugfs_init(struct axis_fifo *fifo)
{
fifo->debugfs_dir = debugfs_create_dir(dev_name(fifo->dt_device), NULL);
debugfs_create_file("regs", 0444, fifo->debugfs_dir, fifo,
&axis_fifo_debugfs_regs_fops);
}
/* read named property from the device tree */
static int get_dts_property(struct axis_fifo *fifo,
char *name, unsigned int *var)
@@ -708,6 +749,8 @@ static int axis_fifo_probe(struct platform_device *pdev)
if (rc < 0)
goto err_initial;
axis_fifo_debugfs_init(fifo);
return 0;
err_initial:
@@ -720,6 +763,7 @@ static void axis_fifo_remove(struct platform_device *pdev)
struct device *dev = &pdev->dev;
struct axis_fifo *fifo = dev_get_drvdata(dev);
debugfs_remove(fifo->debugfs_dir);
misc_deregister(&fifo->miscdev);
dev_set_drvdata(dev, NULL);
}