From a2317231df4b22e6634fe3d8645e7cef848acf49 Mon Sep 17 00:00:00 2001
From: Piotr Kubik <piotr.kubik@adtran.com>
Date: Tue, 26 Aug 2025 14:41:58 +0000
Subject: [PATCH] net: pse-pd: Add Si3474 PSE controller driver

Add a driver for the Skyworks Si3474 I2C Power Sourcing Equipment
controller.

Driver supports basic features of Si3474 IC:
- get port status,
- get port power,
- get port voltage,
- enable/disable port power.

Only 4p configurations are supported at this moment.

Signed-off-by: Piotr Kubik <piotr.kubik@adtran.com>
Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>
Link: https://patch.msgid.link/9b72c8cd-c8d3-4053-9c80-671b9481d166@adtran.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Carlo Szelinsky <github@szelinsky.de>
---
 drivers/net/pse-pd/Kconfig  |  11 +
 drivers/net/pse-pd/Makefile |   1 +
 drivers/net/pse-pd/si3474.c | 578 ++++++++++++++++++++++++++++++++++++
 3 files changed, 590 insertions(+)
 create mode 100644 drivers/net/pse-pd/si3474.c
--- a/drivers/net/pse-pd/Kconfig
+++ b/drivers/net/pse-pd/Kconfig
@@ -32,6 +32,17 @@ config PSE_PD692X0
 	  To compile this driver as a module, choose M here: the
 	  module will be called pd692x0.
 
+config PSE_SI3474
+	tristate "Si3474 PSE controller"
+	depends on I2C
+	help
+	  This module provides support for Si3474 regulator based Ethernet
+	  Power Sourcing Equipment.
+	  Only 4-pair PSE configurations are supported.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called si3474.
+
 config PSE_TPS23881
 	tristate "TPS23881 PSE controller"
 	depends on I2C
--- a/drivers/net/pse-pd/Makefile
+++ b/drivers/net/pse-pd/Makefile
@@ -5,4 +5,5 @@ obj-$(CONFIG_PSE_CONTROLLER) += pse_core
 
 obj-$(CONFIG_PSE_REGULATOR) += pse_regulator.o
 obj-$(CONFIG_PSE_PD692X0) += pd692x0.o
+obj-$(CONFIG_PSE_SI3474) += si3474.o
 obj-$(CONFIG_PSE_TPS23881) += tps23881.o
--- /dev/null
+++ b/drivers/net/pse-pd/si3474.c
@@ -0,0 +1,578 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for the Skyworks Si3474 PoE PSE Controller
+ *
+ * Chip Architecture & Terminology:
+ *
+ * The Si3474 is a single-chip PoE PSE controller managing 8 physical power
+ * delivery channels. Internally, it's structured into two logical "Quads".
+ *
+ * Quad 0: Manages physical channels ('ports' in datasheet) 0, 1, 2, 3
+ * Quad 1: Manages physical channels ('ports' in datasheet) 4, 5, 6, 7
+ *
+ * Each Quad is accessed via a separate I2C address. The base address range is
+ * set by hardware pins A1-A4, and the specific address selects Quad 0 (usually
+ * the lower/even address) or Quad 1 (usually the higher/odd address).
+ * See datasheet Table 2.2 for the address mapping.
+ *
+ * While the Quads manage channel-specific operations, the Si3474 package has
+ * several resources shared across the entire chip:
+ * - Single RESETb input pin.
+ * - Single INTb output pin (signals interrupts from *either* Quad).
+ * - Single OSS input pin (Emergency Shutdown).
+ * - Global I2C Address (0x7F) used for firmware updates.
+ * - Global status monitoring (Temperature, VDD/VPWR Undervoltage Lockout).
+ *
+ * Driver Architecture:
+ *
+ * To handle the mix of per-Quad access and shared resources correctly, this
+ * driver treats the entire Si3474 package as one logical device. The driver
+ * instance associated with the primary I2C address (Quad 0) takes ownership.
+ * It discovers and manages the I2C client for the secondary address (Quad 1).
+ * This primary instance handles shared resources like IRQ management and
+ * registers a single PSE controller device representing all logical PIs.
+ * Internal functions route I2C commands to the appropriate Quad's i2c_client
+ * based on the target channel or PI.
+ *
+ * Terminology Mapping:
+ *
+ * - "PI" (Power Interface): Refers to the logical PSE port as defined by
+ * IEEE 802.3 (typically corresponds to an RJ45 connector). This is the
+ * `id` (0-7) used in the pse_controller_ops.
+ * - "Channel": Refers to one of the 8 physical power control paths within
+ * the Si3474 chip itself (hardware channels 0-7). This terminology is
+ * used internally within the driver to avoid confusion with 'ports'.
+ * - "Quad": One of the two internal 4-channel management units within the
+ * Si3474, each accessed via its own I2C address.
+ *
+ * Relationship:
+ * - A 2-Pair PoE PI uses 1 Channel.
+ * - A 4-Pair PoE PI uses 2 Channels.
+ *
+ * ASCII Schematic:
+ *
+ * +-----------------------------------------------------+
+ * |                    Si3474 Chip                      |
+ * |                                                     |
+ * | +---------------------+     +---------------------+ |
+ * | |      Quad 0         |     |      Quad 1         | |
+ * | | Channels 0, 1, 2, 3 |     | Channels 4, 5, 6, 7 | |
+ * | +----------^----------+     +-------^-------------+ |
+ * | I2C Addr 0 |                        | I2C Addr 1    |
+ * |            +------------------------+               |
+ * | (Primary Driver Instance) (Managed by Primary)      |
+ * |                                                     |
+ * | Shared Resources (affect whole chip):               |
+ * |  - Single INTb Output -> Handled by Primary         |
+ * |  - Single RESETb Input                              |
+ * |  - Single OSS Input   -> Handled by Primary         |
+ * |  - Global I2C Addr (0x7F) for Firmware Update       |
+ * |  - Global Status (Temp, VDD/VPWR UVLO)              |
+ * +-----------------------------------------------------+
+ *        |   |   |   |        |   |   |   |
+ *        Ch0 Ch1 Ch2 Ch3      Ch4 Ch5 Ch6 Ch7  (Physical Channels)
+ *
+ * Example Mapping (Logical PI to Physical Channel(s)):
+ * * 2-Pair Mode (8 PIs):
+ * PI 0 -> Ch 0
+ * PI 1 -> Ch 1
+ * ...
+ * PI 7 -> Ch 7
+ * * 4-Pair Mode (4 PIs):
+ * PI 0 -> Ch 0 + Ch 1  (Managed via Quad 0 Addr)
+ * PI 1 -> Ch 2 + Ch 3  (Managed via Quad 0 Addr)
+ * PI 2 -> Ch 4 + Ch 5  (Managed via Quad 1 Addr)
+ * PI 3 -> Ch 6 + Ch 7  (Managed via Quad 1 Addr)
+ * (Note: Actual mapping depends on Device Tree and PORT_REMAP config)
+ */
+
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pse-pd/pse.h>
+
+#define SI3474_MAX_CHANS 8
+
+#define MANUFACTURER_ID 0x08
+#define IC_ID 0x05
+#define SI3474_DEVICE_ID (MANUFACTURER_ID << 3 | IC_ID)
+
+/* Misc registers */
+#define VENDOR_IC_ID_REG 0x1B
+#define TEMPERATURE_REG 0x2C
+#define FIRMWARE_REVISION_REG 0x41
+#define CHIP_REVISION_REG 0x43
+
+/* Main status registers */
+#define POWER_STATUS_REG 0x10
+#define PORT_MODE_REG 0x12
+#define DETECT_CLASS_ENABLE_REG 0x14
+
+/* PORTn Current */
+#define PORT1_CURRENT_LSB_REG 0x30
+
+/* PORTn Current [mA], return in [nA] */
+/* 1000 * ((PORTn_CURRENT_MSB << 8) + PORTn_CURRENT_LSB) / 16384 */
+#define SI3474_NA_STEP (1000 * 1000 * 1000 / 16384)
+
+/* VPWR Voltage */
+#define VPWR_LSB_REG 0x2E
+#define VPWR_MSB_REG 0x2F
+
+/* PORTn Voltage */
+#define PORT1_VOLTAGE_LSB_REG 0x32
+
+/* VPWR Voltage [V], return in [uV] */
+/* 60 * (( VPWR_MSB << 8) + VPWR_LSB) / 16384 */
+#define SI3474_UV_STEP (1000 * 1000 * 60 / 16384)
+
+/* Helper macros */
+#define CHAN_IDX(chan) ((chan) % 4)
+#define CHAN_BIT(chan) BIT(CHAN_IDX(chan))
+#define CHAN_UPPER_BIT(chan) BIT(CHAN_IDX(chan) + 4)
+
+#define CHAN_MASK(chan) (0x03U << (2 * CHAN_IDX(chan)))
+#define CHAN_REG(base, chan) ((base) + (CHAN_IDX(chan) * 4))
+
+struct si3474_pi_desc {
+	u8 chan[2];
+	bool is_4p;
+};
+
+struct si3474_priv {
+	struct i2c_client *client[2];
+	struct pse_controller_dev pcdev;
+	struct device_node *np;
+	struct si3474_pi_desc pi[SI3474_MAX_CHANS];
+};
+
+static struct si3474_priv *to_si3474_priv(struct pse_controller_dev *pcdev)
+{
+	return container_of(pcdev, struct si3474_priv, pcdev);
+}
+
+static void si3474_get_channels(struct si3474_priv *priv, int id,
+				u8 *chan0, u8 *chan1)
+{
+	*chan0 = priv->pi[id].chan[0];
+	*chan1 = priv->pi[id].chan[1];
+}
+
+static struct i2c_client *si3474_get_chan_client(struct si3474_priv *priv,
+						 u8 chan)
+{
+	return (chan < 4) ? priv->client[0] : priv->client[1];
+}
+
+static int si3474_pi_get_admin_state(struct pse_controller_dev *pcdev, int id,
+				     struct pse_admin_state *admin_state)
+{
+	struct si3474_priv *priv = to_si3474_priv(pcdev);
+	struct i2c_client *client;
+	bool is_enabled;
+	u8 chan0, chan1;
+	s32 ret;
+
+	si3474_get_channels(priv, id, &chan0, &chan1);
+	client = si3474_get_chan_client(priv, chan0);
+
+	ret = i2c_smbus_read_byte_data(client, PORT_MODE_REG);
+	if (ret < 0) {
+		admin_state->c33_admin_state =
+			ETHTOOL_C33_PSE_ADMIN_STATE_UNKNOWN;
+		return ret;
+	}
+
+	is_enabled = ret & (CHAN_MASK(chan0) | CHAN_MASK(chan1));
+
+	if (is_enabled)
+		admin_state->c33_admin_state =
+			ETHTOOL_C33_PSE_ADMIN_STATE_ENABLED;
+	else
+		admin_state->c33_admin_state =
+			ETHTOOL_C33_PSE_ADMIN_STATE_DISABLED;
+
+	return 0;
+}
+
+static int si3474_pi_get_pw_status(struct pse_controller_dev *pcdev, int id,
+				   struct pse_pw_status *pw_status)
+{
+	struct si3474_priv *priv = to_si3474_priv(pcdev);
+	struct i2c_client *client;
+	bool delivering;
+	u8 chan0, chan1;
+	s32 ret;
+
+	si3474_get_channels(priv, id, &chan0, &chan1);
+	client = si3474_get_chan_client(priv, chan0);
+
+	ret = i2c_smbus_read_byte_data(client, POWER_STATUS_REG);
+	if (ret < 0) {
+		pw_status->c33_pw_status = ETHTOOL_C33_PSE_PW_D_STATUS_UNKNOWN;
+		return ret;
+	}
+
+	delivering = ret & (CHAN_UPPER_BIT(chan0) | CHAN_UPPER_BIT(chan1));
+
+	if (delivering)
+		pw_status->c33_pw_status =
+			ETHTOOL_C33_PSE_PW_D_STATUS_DELIVERING;
+	else
+		pw_status->c33_pw_status = ETHTOOL_C33_PSE_PW_D_STATUS_DISABLED;
+
+	return 0;
+}
+
+static int si3474_get_of_channels(struct si3474_priv *priv)
+{
+	struct pse_pi *pi;
+	u32 chan_id;
+	u8 pi_no;
+	s32 ret;
+
+	for (pi_no = 0; pi_no < SI3474_MAX_CHANS; pi_no++) {
+		pi = &priv->pcdev.pi[pi_no];
+		bool pairset_found = false;
+		u8 pairset_no;
+
+		for (pairset_no = 0; pairset_no < 2; pairset_no++) {
+			if (!pi->pairset[pairset_no].np)
+				continue;
+
+			pairset_found = true;
+
+			ret = of_property_read_u32(pi->pairset[pairset_no].np,
+						   "reg", &chan_id);
+			if (ret) {
+				dev_err(&priv->client[0]->dev,
+					"Failed to read channel reg property\n");
+				return ret;
+			}
+			if (chan_id > SI3474_MAX_CHANS) {
+				dev_err(&priv->client[0]->dev,
+					"Incorrect channel number: %d\n", chan_id);
+				return -EINVAL;
+			}
+
+			priv->pi[pi_no].chan[pairset_no] = chan_id;
+			/* Mark as 4-pair if second pairset is present */
+			priv->pi[pi_no].is_4p = (pairset_no == 1);
+		}
+
+		if (pairset_found && !priv->pi[pi_no].is_4p) {
+			dev_err(&priv->client[0]->dev,
+				"Second pairset is missing for PI %pOF, only 4p configs are supported\n",
+				pi->np);
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static int si3474_setup_pi_matrix(struct pse_controller_dev *pcdev)
+{
+	struct si3474_priv *priv = to_si3474_priv(pcdev);
+	s32 ret;
+
+	ret = si3474_get_of_channels(priv);
+	if (ret < 0)
+		dev_warn(&priv->client[0]->dev,
+			 "Unable to parse DT PSE power interface matrix\n");
+
+	return ret;
+}
+
+static int si3474_pi_enable(struct pse_controller_dev *pcdev, int id)
+{
+	struct si3474_priv *priv = to_si3474_priv(pcdev);
+	struct i2c_client *client;
+	u8 chan0, chan1;
+	s32 ret;
+	u8 val;
+
+	si3474_get_channels(priv, id, &chan0, &chan1);
+	client = si3474_get_chan_client(priv, chan0);
+
+	/* Release PI from shutdown */
+	ret = i2c_smbus_read_byte_data(client, PORT_MODE_REG);
+	if (ret < 0)
+		return ret;
+
+	val = (u8)ret;
+	val |= CHAN_MASK(chan0);
+	val |= CHAN_MASK(chan1);
+
+	ret = i2c_smbus_write_byte_data(client, PORT_MODE_REG, val);
+	if (ret)
+		return ret;
+
+	/* DETECT_CLASS_ENABLE must be set when using AUTO mode,
+	 * otherwise PI does not power up - datasheet section 2.10.2
+	 */
+	val = CHAN_BIT(chan0) | CHAN_UPPER_BIT(chan0) |
+	      CHAN_BIT(chan1) | CHAN_UPPER_BIT(chan1);
+
+	ret = i2c_smbus_write_byte_data(client, DETECT_CLASS_ENABLE_REG, val);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int si3474_pi_disable(struct pse_controller_dev *pcdev, int id)
+{
+	struct si3474_priv *priv = to_si3474_priv(pcdev);
+	struct i2c_client *client;
+	u8 chan0, chan1;
+	s32 ret;
+	u8 val;
+
+	si3474_get_channels(priv, id, &chan0, &chan1);
+	client = si3474_get_chan_client(priv, chan0);
+
+	/* Set PI in shutdown mode */
+	ret = i2c_smbus_read_byte_data(client, PORT_MODE_REG);
+	if (ret < 0)
+		return ret;
+
+	val = (u8)ret;
+	val &= ~CHAN_MASK(chan0);
+	val &= ~CHAN_MASK(chan1);
+
+	ret = i2c_smbus_write_byte_data(client, PORT_MODE_REG, val);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int si3474_pi_get_chan_current(struct si3474_priv *priv, u8 chan)
+{
+	struct i2c_client *client;
+	u64 tmp_64;
+	s32 ret;
+	u8 reg;
+
+	client = si3474_get_chan_client(priv, chan);
+
+	/* Registers 0x30 to 0x3d */
+	reg = CHAN_REG(PORT1_CURRENT_LSB_REG, chan);
+
+	ret = i2c_smbus_read_word_data(client, reg);
+	if (ret < 0)
+		return ret;
+
+	tmp_64 = ret * SI3474_NA_STEP;
+
+	/* uA = nA / 1000 */
+	tmp_64 = DIV_ROUND_CLOSEST_ULL(tmp_64, 1000);
+	return (int)tmp_64;
+}
+
+static int si3474_pi_get_chan_voltage(struct si3474_priv *priv, u8 chan)
+{
+	struct i2c_client *client;
+	s32 ret;
+	u32 val;
+	u8 reg;
+
+	client = si3474_get_chan_client(priv, chan);
+
+	/* Registers 0x32 to 0x3f */
+	reg = CHAN_REG(PORT1_VOLTAGE_LSB_REG, chan);
+
+	ret = i2c_smbus_read_word_data(client, reg);
+	if (ret < 0)
+		return ret;
+
+	val = ret * SI3474_UV_STEP;
+
+	return (int)val;
+}
+
+static int si3474_pi_get_voltage(struct pse_controller_dev *pcdev, int id)
+{
+	struct si3474_priv *priv = to_si3474_priv(pcdev);
+	struct i2c_client *client;
+	u8 chan0, chan1;
+	s32 ret;
+
+	si3474_get_channels(priv, id, &chan0, &chan1);
+	client = si3474_get_chan_client(priv, chan0);
+
+	/* Check which channels are enabled*/
+	ret = i2c_smbus_read_byte_data(client, POWER_STATUS_REG);
+	if (ret < 0)
+		return ret;
+
+	/* Take voltage from the first enabled channel */
+	if (ret & CHAN_BIT(chan0))
+		ret = si3474_pi_get_chan_voltage(priv, chan0);
+	else if (ret & CHAN_BIT(chan1))
+		ret = si3474_pi_get_chan_voltage(priv, chan1);
+	else
+		/* 'should' be no voltage in this case */
+		return 0;
+
+	return ret;
+}
+
+static int si3474_pi_get_actual_pw(struct pse_controller_dev *pcdev, int id)
+{
+	struct si3474_priv *priv = to_si3474_priv(pcdev);
+	u8 chan0, chan1;
+	u32 uV, uA;
+	u64 tmp_64;
+	s32 ret;
+
+	ret = si3474_pi_get_voltage(&priv->pcdev, id);
+
+	/* Do not read currents if voltage is 0 */
+	if (ret <= 0)
+		return ret;
+	uV = ret;
+
+	si3474_get_channels(priv, id, &chan0, &chan1);
+
+	ret = si3474_pi_get_chan_current(priv, chan0);
+	if (ret < 0)
+		return ret;
+	uA = ret;
+
+	ret = si3474_pi_get_chan_current(priv, chan1);
+	if (ret < 0)
+		return ret;
+	uA += ret;
+
+	tmp_64 = uV;
+	tmp_64 *= uA;
+	/* mW = uV * uA / 1000000000 */
+	return DIV_ROUND_CLOSEST_ULL(tmp_64, 1000000000);
+}
+
+static const struct pse_controller_ops si3474_ops = {
+	.setup_pi_matrix = si3474_setup_pi_matrix,
+	.pi_enable = si3474_pi_enable,
+	.pi_disable = si3474_pi_disable,
+	.pi_get_actual_pw = si3474_pi_get_actual_pw,
+	.pi_get_voltage = si3474_pi_get_voltage,
+	.pi_get_admin_state = si3474_pi_get_admin_state,
+	.pi_get_pw_status = si3474_pi_get_pw_status,
+};
+
+static void si3474_ancillary_i2c_remove(void *data)
+{
+	struct i2c_client *client = data;
+
+	i2c_unregister_device(client);
+}
+
+static int si3474_i2c_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct si3474_priv *priv;
+	u8 fw_version;
+	s32 ret;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+		dev_err(dev, "i2c check functionality failed\n");
+		return -ENXIO;
+	}
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	ret = i2c_smbus_read_byte_data(client, VENDOR_IC_ID_REG);
+	if (ret < 0)
+		return ret;
+
+	if (ret != SI3474_DEVICE_ID) {
+		dev_err(dev, "Wrong device ID: 0x%x\n", ret);
+		return -ENXIO;
+	}
+
+	ret = i2c_smbus_read_byte_data(client, FIRMWARE_REVISION_REG);
+	if (ret < 0)
+		return ret;
+	fw_version = ret;
+
+	ret = i2c_smbus_read_byte_data(client, CHIP_REVISION_REG);
+	if (ret < 0)
+		return ret;
+
+	dev_dbg(dev, "Chip revision: 0x%x, firmware version: 0x%x\n",
+		ret, fw_version);
+
+	priv->client[0] = client;
+	i2c_set_clientdata(client, priv);
+
+	priv->client[1] = i2c_new_ancillary_device(priv->client[0], "secondary",
+						   priv->client[0]->addr + 1);
+	if (IS_ERR(priv->client[1]))
+		return PTR_ERR(priv->client[1]);
+
+	ret = devm_add_action_or_reset(dev, si3474_ancillary_i2c_remove, priv->client[1]);
+	if (ret < 0) {
+		dev_err(&priv->client[1]->dev, "Cannot register remove callback\n");
+		return ret;
+	}
+
+	ret = i2c_smbus_read_byte_data(priv->client[1], VENDOR_IC_ID_REG);
+	if (ret < 0) {
+		dev_err(&priv->client[1]->dev, "Cannot access secondary PSE controller\n");
+		return ret;
+	}
+
+	if (ret != SI3474_DEVICE_ID) {
+		dev_err(&priv->client[1]->dev,
+			"Wrong device ID for secondary PSE controller: 0x%x\n", ret);
+		return -ENXIO;
+	}
+
+	priv->np = dev->of_node;
+	priv->pcdev.owner = THIS_MODULE;
+	priv->pcdev.ops = &si3474_ops;
+	priv->pcdev.dev = dev;
+	priv->pcdev.types = ETHTOOL_PSE_C33;
+	priv->pcdev.nr_lines = SI3474_MAX_CHANS;
+
+	ret = devm_pse_controller_register(dev, &priv->pcdev);
+	if (ret) {
+		dev_err(dev, "Failed to register PSE controller: 0x%x\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct i2c_device_id si3474_id[] = {
+	{ "si3474" },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, si3474_id);
+
+static const struct of_device_id si3474_of_match[] = {
+	{
+		.compatible = "skyworks,si3474",
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, si3474_of_match);
+
+static struct i2c_driver si3474_driver = {
+	.probe = si3474_i2c_probe,
+	.id_table = si3474_id,
+	.driver = {
+		.name = "si3474",
+		.of_match_table = si3474_of_match,
+	},
+};
+module_i2c_driver(si3474_driver);
+
+MODULE_AUTHOR("Piotr Kubik <piotr.kubik@adtran.com>");
+MODULE_DESCRIPTION("Skyworks Si3474 PoE PSE Controller driver");
+MODULE_LICENSE("GPL");
