[RFC PATCH 6/7] i3c: hub: p3h2x4x: configure target ports placed in GPIO mode
From: Lakshay Piplani
Date: Fri Oct 16 2026 - 12:55:19 EST
Add a GPIO target port mode, selected by a "gpio@N" device tree node, and
program the target port GPIO mode register that was defined but never
written.
GPIO mode has higher priority than the SMBus agent and the Hub Network
connection and leaves the port disconnected from the network, so commit it
with the other port mode bits while the protected registers are unlocked,
and exclude the port from the Controller Port multiplexer request along
with the SMBus ports.
The mode enable is a protected register owned by this driver, while the
direction and level registers are driven by the GPIO child, so move the
mode enable to the shared MFD header.
Signed-off-by: Lakshay Piplani <lakshay.piplani@xxxxxxx>
Signed-off-by: Aman Kumar Pandey <aman.kumarpandey@xxxxxxx>
Signed-off-by: Vikash Bansal <vikash.bansal@xxxxxxx>
---
drivers/i3c/hub/p3h2840_i3c_hub.h | 8 +-----
drivers/i3c/hub/p3h2840_i3c_hub_common.c | 34 +++++++++++++++++++-----
include/linux/mfd/p3h2840.h | 8 ++++++
3 files changed, 36 insertions(+), 14 deletions(-)
diff --git a/drivers/i3c/hub/p3h2840_i3c_hub.h b/drivers/i3c/hub/p3h2840_i3c_hub.h
index ad2e7cb7f5ea..595e3ec60fd2 100644
--- a/drivers/i3c/hub/p3h2840_i3c_hub.h
+++ b/drivers/i3c/hub/p3h2840_i3c_hub.h
@@ -73,7 +73,6 @@
#define P3H2X4X_IBI_MDB_CUSTOM 0x1c
#define P3H2X4X_JEDEC_CONTEXT_ID 0x1d
-#define P3H2X4X_TP_GPIO_MODE_EN 0x1e
/* Device Status and IBI Registers */
#define P3H2X4X_DEV_AND_IBI_STS 0x20
@@ -92,17 +91,11 @@
#define P3H2X4X_TP_PULLUP_EN 0x53
-#define P3H2X4X_TP_SCL_OUT_EN 0x54
-#define P3H2X4X_TP_SDA_OUT_EN 0x55
-#define P3H2X4X_TP_SCL_OUT_LEVEL 0x56
-#define P3H2X4X_TP_SDA_OUT_LEVEL 0x57
#define P3H2X4X_TP_IN_DETECT_MODE_CONF 0x58
#define P3H2X4X_TP_SCL_IN_DETECT_IBI_EN 0x59
#define P3H2X4X_TP_SDA_IN_DETECT_IBI_EN 0x5a
/* Target Ports Status Registers */
-#define P3H2X4X_TP_SCL_IN_LEVEL_STS 0x60
-#define P3H2X4X_TP_SDA_IN_LEVEL_STS 0x61
#define P3H2X4X_TP_SCL_IN_DETECT_FLG 0x62
#define P3H2X4X_TP_SDA_IN_DETECT_FLG 0x63
@@ -302,6 +295,7 @@ enum p3h2x4x_rcv_buf {
enum p3h2x4x_tp_mode {
P3H2X4X_TP_MODE_I3C,
P3H2X4X_TP_MODE_SMBUS,
+ P3H2X4X_TP_MODE_GPIO,
};
struct tp_configuration {
diff --git a/drivers/i3c/hub/p3h2840_i3c_hub_common.c b/drivers/i3c/hub/p3h2840_i3c_hub_common.c
index 906034632a94..0caf69b3cc1d 100644
--- a/drivers/i3c/hub/p3h2840_i3c_hub_common.c
+++ b/drivers/i3c/hub/p3h2840_i3c_hub_common.c
@@ -98,7 +98,7 @@ static int p3h2x4x_configure_tp(struct device *dev)
{
struct p3h2x4x_i3c_hub_dev *hub = dev_get_drvdata(dev);
struct p3h2x4x *p3h2x4x = dev_get_drvdata(dev->parent);
- u8 mode = 0, smbus = 0, pullup = 0, target_port = 0;
+ u8 mode = 0, smbus = 0, pullup = 0, target_port = 0, gpio = 0;
u8 tp_mask;
int tp, ret;
@@ -110,6 +110,8 @@ static int p3h2x4x_configure_tp(struct device *dev)
P3H2X4X_SET_BIT(tp) : 0;
target_port |= (hub->tp_bus[tp].tp_mask == P3H2X4X_SET_BIT(tp)) ?
hub->tp_bus[tp].tp_mask : 0;
+ gpio |= (hub->hub_config.tp_config[tp].mode == P3H2X4X_TP_MODE_GPIO) ?
+ P3H2X4X_SET_BIT(tp) : 0;
}
/* Only touch the bits for the target ports this variant provides. */
@@ -127,7 +129,19 @@ static int p3h2x4x_configure_tp(struct device *dev)
if (ret)
return ret;
- if (target_port & ~smbus) {
+ /*
+ * GPIO mode takes priority over the SMBus agent and the Hub Network
+ * connection, and leaves the port disconnected from the network
+ * (datasheet Table 10). Program it here, together with the other port
+ * mode bits, so the port function is committed in one place. The GPIO
+ * child driver then only touches the unprotected direction and level
+ * registers.
+ */
+ ret = regmap_update_bits(hub->regmap, P3H2X4X_TP_GPIO_MODE_EN, tp_mask, gpio);
+ if (ret)
+ return ret;
+
+ if (target_port & ~(smbus | gpio)) {
ret = regmap_write(hub->regmap, P3H2X4X_CP_MUX_SET,
P3H2X4X_CONTROLLER_PORT_MUX_REQ);
if (ret)
@@ -206,14 +220,16 @@ static int p3h2x4x_parse_tp_dt_settings(struct device *dev,
enum p3h2x4x_tp_mode mode;
/*
- * Only "i3c" and "smbus" children describe target ports. Skip any
- * other child (for example the MFD "regulators" container), which
- * has no "reg" property.
+ * Only "i3c", "smbus" and "gpio" children describe target ports.
+ * Skip any other child (for example the MFD "regulators"
+ * container), which has no "reg" property.
*/
if (of_node_name_eq(tp_node, "i3c"))
mode = P3H2X4X_TP_MODE_I3C;
else if (of_node_name_eq(tp_node, "smbus"))
mode = P3H2X4X_TP_MODE_SMBUS;
+ else if (of_node_name_eq(tp_node, "gpio"))
+ mode = P3H2X4X_TP_MODE_GPIO;
else
continue;
@@ -373,10 +389,14 @@ DEFINE_DEBUGFS_ATTRIBUTE(p3h2x4x_i3c_hub_offset_reg, p3h2x4x_i3c_hub_offset_reg_
static int p3h2x4x_i3c_hub_tp_mode_show(struct seq_file *s, void *data)
{
+ static const char * const mode_names[] = {
+ [P3H2X4X_TP_MODE_I3C] = "i3c",
+ [P3H2X4X_TP_MODE_SMBUS] = "smbus",
+ [P3H2X4X_TP_MODE_GPIO] = "gpio",
+ };
const struct tp_configuration *tp_config = s->private;
- seq_printf(s, "%s\n",
- tp_config->mode == P3H2X4X_TP_MODE_SMBUS ? "smbus" : "i3c");
+ seq_printf(s, "%s\n", mode_names[tp_config->mode]);
return 0;
}
diff --git a/include/linux/mfd/p3h2840.h b/include/linux/mfd/p3h2840.h
index eb4792de5440..537ff7d28690 100644
--- a/include/linux/mfd/p3h2840.h
+++ b/include/linux/mfd/p3h2840.h
@@ -24,6 +24,14 @@
#define P3H2X4X_REGISTERS_UNLOCK_CODE 0x69
#define P3H2X4X_CP1_REGISTERS_UNLOCK_CODE 0x6a
+/*
+ * Target port GPIO mode enable, one bit per target port. Shared because the
+ * hub driver owns this protected register while the GPIO driver depends on it
+ * to know which ports it may drive. The direction and level registers are not
+ * protected and are private to the GPIO driver.
+ */
+#define P3H2X4X_TP_GPIO_MODE_EN 0x1e
+
#define I3C_MANUF_ID_NXP 0x011b
struct p3h2x4x_i3c_hub_dev;
--
2.25.1