[RFC PATCH 1/7] i3c: hub: p3h2x4x: Add support for debugfs
Lakshay Piplani
lakshay.piplani at nxp.com
Fri Oct 16 09:46:19 PDT 2026
Add debugfs support to expose configurations and registers information
for the P3H2x4x I3C hub.
This change adds a debugfs interface that allows inspection of current HUB,
control port and target port configurations. It also provides a simple
mechanism to read and write HUB registers.
Signed-off-by: Aman Kumar Pandey <aman.kumarpandey at nxp.com>
Signed-off-by: Vikash Bansal <vikash.bansal at nxp.com>
Signed-off-by: Lakshay Piplani <lakshay.piplani at nxp.com>
---
drivers/i3c/hub/p3h2840_i3c_hub.h | 7 +
drivers/i3c/hub/p3h2840_i3c_hub_common.c | 188 ++++++++++++++++++++++-
2 files changed, 194 insertions(+), 1 deletion(-)
diff --git a/drivers/i3c/hub/p3h2840_i3c_hub.h b/drivers/i3c/hub/p3h2840_i3c_hub.h
index 0e59351e7b6d..5b3fb1752c7b 100644
--- a/drivers/i3c/hub/p3h2840_i3c_hub.h
+++ b/drivers/i3c/hub/p3h2840_i3c_hub.h
@@ -14,6 +14,9 @@
#include <linux/i3c/master.h>
#include <linux/regulator/consumer.h>
#include <linux/regmap.h>
+#ifdef CONFIG_DEBUG_FS
+#include <linux/debugfs.h>
+#endif
/* I3C HUB REGISTERS */
@@ -313,6 +316,10 @@ struct tp_bus {
};
struct p3h2x4x_i3c_hub_dev {
+#ifdef CONFIG_DEBUG_FS
+ u8 reg_addr; /* Offset of the HUB register to read or write. */
+ struct dentry *debugfs_dir;
+#endif
struct device *dev;
struct regmap *regmap;
struct mutex etx_mutex; /* all port mutex */
diff --git a/drivers/i3c/hub/p3h2840_i3c_hub_common.c b/drivers/i3c/hub/p3h2840_i3c_hub_common.c
index 0c18459d7ec6..906034632a94 100644
--- a/drivers/i3c/hub/p3h2840_i3c_hub_common.c
+++ b/drivers/i3c/hub/p3h2840_i3c_hub_common.c
@@ -298,6 +298,192 @@ static void p3h2x4x_clear_i3c_hub_priv(void *data)
p3h2x4x->i3c_hub_priv = NULL;
}
+#ifdef CONFIG_DEBUG_FS
+
+static int p3h2x4x_i3c_hub_access_reg_get(void *dvrdata, u64 *val)
+{
+ struct p3h2x4x_i3c_hub_dev *p3h2x4x_i3c_hub = dvrdata;
+ u32 reg_val;
+ int ret;
+
+ ret = regmap_read(p3h2x4x_i3c_hub->regmap, p3h2x4x_i3c_hub->reg_addr, ®_val);
+ if (ret)
+ return ret;
+
+ *val = reg_val & 0xFF;
+ return 0;
+}
+
+static int p3h2x4x_i3c_hub_access_reg_set(void *dvrdata, u64 val)
+{
+ struct p3h2x4x_i3c_hub_dev *p3h2x4x_i3c_hub = dvrdata;
+ struct p3h2x4x *p3h2x4x = dev_get_drvdata(p3h2x4x_i3c_hub->dev->parent);
+ int ret, ret2;
+
+ /* HUB registers are one byte wide, reject anything that does not fit. */
+ if (val > U8_MAX)
+ return -EINVAL;
+
+ scoped_guard(mutex, &p3h2x4x->protected_reg_lock) {
+ ret = regmap_write(p3h2x4x_i3c_hub->regmap,
+ P3H2X4X_DEV_REG_PROTECTION_CODE,
+ P3H2X4X_REGISTERS_UNLOCK_CODE);
+ if (ret)
+ break;
+
+ ret = regmap_write(p3h2x4x_i3c_hub->regmap,
+ p3h2x4x_i3c_hub->reg_addr, val);
+
+ ret2 = regmap_write(p3h2x4x_i3c_hub->regmap,
+ P3H2X4X_DEV_REG_PROTECTION_CODE,
+ P3H2X4X_REGISTERS_LOCK_CODE);
+ if (!ret && ret2)
+ ret = ret2;
+ }
+
+ return ret;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(p3h2x4x_i3c_hub_access_reg, p3h2x4x_i3c_hub_access_reg_get,
+ p3h2x4x_i3c_hub_access_reg_set, "%llx\n");
+
+static int p3h2x4x_i3c_hub_offset_reg_get(void *dvrdata, u64 *val)
+{
+ struct p3h2x4x_i3c_hub_dev *p3h2x4x_i3c_hub = dvrdata;
+
+ *val = p3h2x4x_i3c_hub->reg_addr;
+
+ return 0;
+}
+
+static int p3h2x4x_i3c_hub_offset_reg_set(void *dvrdata, u64 val)
+{
+ struct p3h2x4x_i3c_hub_dev *p3h2x4x_i3c_hub = dvrdata;
+
+ if (val > U8_MAX)
+ return -EINVAL;
+
+ p3h2x4x_i3c_hub->reg_addr = val;
+
+ return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(p3h2x4x_i3c_hub_offset_reg, p3h2x4x_i3c_hub_offset_reg_get,
+ p3h2x4x_i3c_hub_offset_reg_set, "%llx\n");
+
+static int p3h2x4x_i3c_hub_tp_mode_show(struct seq_file *s, void *data)
+{
+ const struct tp_configuration *tp_config = s->private;
+
+ seq_printf(s, "%s\n",
+ tp_config->mode == P3H2X4X_TP_MODE_SMBUS ? "smbus" : "i3c");
+
+ return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(p3h2x4x_i3c_hub_tp_mode);
+
+static void p3h2x4x_i3c_hub_debugfs_remove(void *data)
+{
+ struct p3h2x4x_i3c_hub_dev *p3h2x4x_i3c_hub = data;
+
+ debugfs_remove_recursive(p3h2x4x_i3c_hub->debugfs_dir);
+}
+
+static int p3h2x4x_i3c_hub_debugfs_init(struct p3h2x4x_i3c_hub_dev *p3h2x4x_i3c_hub)
+{
+ struct device *dev = p3h2x4x_i3c_hub->dev;
+ struct dentry *conf_dir;
+ struct dentry *tp_dir;
+ struct dentry *cp_dir;
+ struct dentry *reg_dir;
+ char hub_id[64];
+ char dir_name[32];
+ int i;
+
+ if (p3h2x4x_i3c_hub->i3cdev) {
+ snprintf(hub_id, sizeof(hub_id), "i3c-hub-device-%d-%llx",
+ i3c_dev_get_master(p3h2x4x_i3c_hub->i3cdev->desc)->bus.id,
+ p3h2x4x_i3c_hub->i3cdev->desc->info.pid);
+ } else {
+ struct i2c_client *client = to_i2c_client(dev->parent);
+
+ /*
+ * Include the client address, the adapter number alone is not
+ * unique when more than one HUB sits on the same I2C adapter
+ * and the resulting debugfs directory name would collide.
+ */
+ snprintf(hub_id, sizeof(hub_id), "i3c-hub-device-%d-%02x",
+ client->adapter->nr, client->addr);
+ }
+
+ p3h2x4x_i3c_hub->debugfs_dir = debugfs_create_dir(hub_id, NULL);
+
+ conf_dir = debugfs_create_dir("dt-p3h2x4x-conf", p3h2x4x_i3c_hub->debugfs_dir);
+
+ cp_dir = debugfs_create_dir("p3h2x4x-control-ports", conf_dir);
+
+ debugfs_create_u32("cp0-io-strength-ohms", 0400, cp_dir,
+ &p3h2x4x_i3c_hub->hub_config.cp0_io_strength);
+
+ debugfs_create_u32("cp1-io-strength-ohms", 0400, cp_dir,
+ &p3h2x4x_i3c_hub->hub_config.cp1_io_strength);
+
+ for (i = 0; i < P3H2X4X_TP_MAX_COUNT; ++i) {
+ struct tp_configuration *tp_config = &p3h2x4x_i3c_hub->hub_config.tp_config[i];
+
+ snprintf(dir_name, sizeof(dir_name), "target-port-%d", i);
+
+ tp_dir = debugfs_create_dir(dir_name, conf_dir);
+
+ debugfs_create_file("mode", 0400, tp_dir, tp_config,
+ &p3h2x4x_i3c_hub_tp_mode_fops);
+
+ debugfs_create_bool("pullup-enable", 0400, tp_dir, &tp_config->pullup_en);
+
+ debugfs_create_bool("ibi-enable", 0400, tp_dir, &tp_config->ibi_en);
+
+ debugfs_create_bool("always-enable", 0400, tp_dir, &tp_config->always_enable);
+
+ /*
+ * Target ports are grouped in fours (0145 and 2367) and each
+ * group shares a single I/O strength and pull-up setting.
+ */
+ if ((i / 2) % 2 == 0) {
+ debugfs_create_u32("io-strength-ohms", 0400, tp_dir,
+ &p3h2x4x_i3c_hub->hub_config.tp0145_io_strength);
+
+ debugfs_create_u32("internal-pullups-ohms", 0400, tp_dir,
+ &p3h2x4x_i3c_hub->hub_config.tp0145_pullup);
+ } else {
+ debugfs_create_u32("io-strength-ohms", 0400, tp_dir,
+ &p3h2x4x_i3c_hub->hub_config.tp2367_io_strength);
+
+ debugfs_create_u32("internal-pullups-ohms", 0400, tp_dir,
+ &p3h2x4x_i3c_hub->hub_config.tp2367_pullup);
+ }
+ }
+
+ reg_dir = debugfs_create_dir("reg", p3h2x4x_i3c_hub->debugfs_dir);
+
+ debugfs_create_file_unsafe("access", 0600, reg_dir, p3h2x4x_i3c_hub,
+ &p3h2x4x_i3c_hub_access_reg);
+
+ debugfs_create_file_unsafe("offset", 0600, reg_dir, p3h2x4x_i3c_hub,
+ &p3h2x4x_i3c_hub_offset_reg);
+
+ return devm_add_action_or_reset(dev, p3h2x4x_i3c_hub_debugfs_remove,
+ p3h2x4x_i3c_hub);
+}
+
+#else
+
+static inline int p3h2x4x_i3c_hub_debugfs_init(struct p3h2x4x_i3c_hub_dev *p3h2x4x_i3c_hub)
+{
+ return 0;
+}
+
+#endif /* CONFIG_DEBUG_FS */
+
static int p3h2x4x_i3c_hub_probe(struct platform_device *pdev)
{
struct p3h2x4x *p3h2x4x = dev_get_drvdata(pdev->dev.parent);
@@ -387,7 +573,7 @@ static int p3h2x4x_i3c_hub_probe(struct platform_device *pdev)
if (ret)
return ret;
- return 0;
+ return p3h2x4x_i3c_hub_debugfs_init(p3h2x4x_i3c_hub);
}
static const struct platform_device_id p3h2x4x_i3c_hub_id[] = {
--
2.25.1
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