The MAX9286 provides several read-only status registers for observing
the system state of the device.
Provide error statistics and link status through debugfs files.
These files will be free-form and should not be considered as part
of any userspace API
Signed-off-by: Kieran Bingham <kieran.bingham+renesas@xxxxxxxxxxxxxxxx>
---
Please consider this a starting point for adding useful debug. I don't
necessarily expect this code to make it to the final driver, but it
could be very useful to process and expose this information internally
in the driver.
Alternatively - we could move this all to max9286_debugfs.c or such.
Watch out for a lot of the error counters which reset to 0 when read.
We should handle those by adding the value to a local store on every
read.
v2:
- Cleanup debugfs in error path of probe()
v6:
- Fix a bogus (h << 0) check
---
drivers/media/i2c/max9286.c | 127 ++++++++++++++++++++++++++++++++++++
1 file changed, 127 insertions(+)
diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
index df77871e603c..6e1dfc518e03 100644
--- a/drivers/media/i2c/max9286.c
+++ b/drivers/media/i2c/max9286.c
@@ -10,6 +10,7 @@
* Copyright (C) 2015 Cogent Embedded, Inc.
*/
+#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/fwnode.h>
@@ -148,6 +149,7 @@ struct max9286_priv {
struct v4l2_subdev sd;
struct media_pad pads[MAX9286_N_PADS];
struct regulator *regulator;
+ struct dentry *dbgroot;
bool poc_enabled;
struct gpio_chip gpio;
@@ -225,6 +227,124 @@ static int max9286_write(struct max9286_priv *priv, u8 reg, u8 val)
return ret;
}
+/* -----------------------------------------------------------------------------
+ * DebugFS
+ */
+
+#define DEBUGFS_RO_ATTR(name) \
+static int name##_open(struct inode *inode, struct file *file) \
+{ \
+ return single_open(file, name, inode->i_private); \
+} \
+static const struct file_operations name##_fops = { \
+ .owner = THIS_MODULE, \
+ .open = name##_open, \
+ .llseek = seq_lseek, \
+ .read = seq_read, \
+ .release = single_release, \
+}
+
+static int max9286_config_video_detect(struct max9286_priv *priv,
+ struct seq_file *s)
+{
+ int reg_49 = max9286_read(priv, 0x49);
+ unsigned int i;
+
+ if (reg_49 < 0)
+ return reg_49;
+
+ seq_puts(s, " : 0 1 2 3\n");
+ seq_puts(s, "Configuration Link:");
+ for (i = 0; i < 4; i++) {
+ int link = (reg_49 & BIT(i + 4));
+
+ seq_printf(s, " %3s", link ? " O " : "xxx");
+ }
+ seq_puts(s, "\n");
+
+ seq_puts(s, "Video Link :");
+ for (i = 0; i < 4; i++) {
+ int link = (reg_49 & BIT(i));
+
+ seq_printf(s, " %3s", link ? " O " : "xxx");
+ }
+ seq_puts(s, "\n");
+
+ return 0;
+}
+
+static int max9286_vs_period(struct max9286_priv *priv, struct seq_file *s)
+{
+ int l, m, h;
+ unsigned int frame_length;
+
+ l = max9286_read(priv, 0x5b);
+ m = max9286_read(priv, 0x5c);
+ h = max9286_read(priv, 0x5d);
+
+ if (l < 0 || m < 0 || h < 0)
+ return -ENODEV;
+
+ frame_length = (h << 16) + (m << 8) + l;
+
+ seq_printf(s, "Calculated VS Period (pxclk) : %u\n", frame_length);
+
+ return 0;
+}
+
+static int max9286_master_link(struct max9286_priv *priv, struct seq_file *s)
+{
+ int reg_71 = max9286_read(priv, 0x71);
+ unsigned int link = (reg_71 >> 4) & 0x03;
+
+ if (reg_71 < 0)
+ return reg_71;
+
+ seq_printf(s, "Master link selected : %u\n", link);
+
+ return 0;
+}
+
+static int max9286_debugfs_info(struct seq_file *s, void *p)
+{
+ struct max9286_priv *priv = s->private;
+
+ max9286_config_video_detect(priv, s);
+ max9286_vs_period(priv, s);
+ max9286_master_link(priv, s);
+
+ return 0;
+}
+
+DEBUGFS_RO_ATTR(max9286_debugfs_info);
+
+static int max9286_debugfs_init(struct max9286_priv *priv)
+{
+ char name[32];
+
+ snprintf(name, sizeof(name), "max9286-%s",
+ dev_name(&priv->client->dev));
+
+ priv->dbgroot = debugfs_create_dir(name, NULL);
+ if (!priv->dbgroot)
+ return -ENOMEM;
+
+ /*
+ * dentry pointers are discarded, and remove_recursive is used to
+ * cleanup the tree. DEBUGFS_RO_ATTR defines the file operations with
+ * the _fops extension to the function name.
+ */
+ debugfs_create_file("info", 0444, priv->dbgroot, priv,
+ &max9286_debugfs_info_fops);
+
+ return 0;
+}
+
+static void max9286_debugfs_remove(struct max9286_priv *priv)
+{
+ debugfs_remove_recursive(priv->dbgroot);
+}
+
/* -----------------------------------------------------------------------------
* I2C Multiplexer
*/
@@ -1094,6 +1214,9 @@ static int max9286_probe(struct i2c_client *client)
*/
max9286_configure_i2c(priv, false);
+ /* Add any userspace support before we return early. */
+ max9286_debugfs_init(priv);
+
ret = max9286_init(&client->dev);
if (ret < 0)
goto err_regulator;
@@ -1104,6 +1227,7 @@ static int max9286_probe(struct i2c_client *client)
regulator_put(priv->regulator);
max9286_i2c_mux_close(priv);
max9286_configure_i2c(priv, false);
+ max9286_debugfs_remove(priv);
err_free:
max9286_cleanup_dt(priv);
kfree(priv);
@@ -1115,6 +1239,9 @@ static int max9286_remove(struct i2c_client *client)
{
struct max9286_priv *priv = i2c_get_clientdata(client);
+ /* Remove all Debugfs / sysfs entries */
+ max9286_debugfs_remove(priv);
+
i2c_mux_del_adapters(priv->mux);
fwnode_handle_put(priv->sd.fwnode);
--
2.20.1
