@@ -17455,6 +17455,7 @@ NUVOTON NCT6694 MFD DRIVER
M: Ming Yu <tmyu0@nuvoton.com>
S: Supported
F: drivers/gpio/gpio-nct6694.c
+F: drivers/i2c/busses/i2c-nct6694.c
F: drivers/mfd/nct6694.c
F: include/linux/mfd/nct6694.h
@@ -1347,6 +1347,16 @@ config I2C_LJCA
This driver can also be built as a module. If so, the module
will be called i2c-ljca.
+config I2C_NCT6694
+ tristate "Nuvoton NCT6694 I2C adapter support"
+ depends on MFD_NCT6694
+ help
+ If you say yes to this option, support will be included for Nuvoton
+ NCT6694, a USB to I2C interface.
+
+ This driver can also be built as a module. If so, the module will
+ be called i2c-nct6694.
+
config I2C_CP2615
tristate "Silicon Labs CP2615 USB sound card and I2C adapter"
depends on USB
@@ -134,6 +134,7 @@ obj-$(CONFIG_I2C_GXP) += i2c-gxp.o
obj-$(CONFIG_I2C_DIOLAN_U2C) += i2c-diolan-u2c.o
obj-$(CONFIG_I2C_DLN2) += i2c-dln2.o
obj-$(CONFIG_I2C_LJCA) += i2c-ljca.o
+obj-$(CONFIG_I2C_NCT6694) += i2c-nct6694.o
obj-$(CONFIG_I2C_CP2615) += i2c-cp2615.o
obj-$(CONFIG_I2C_PARPORT) += i2c-parport.o
obj-$(CONFIG_I2C_PCI1XXXX) += i2c-mchp-pci1xxxx.o
new file mode 100644
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Nuvoton NCT6694 I2C adapter driver based on USB interface.
+ *
+ * Copyright (C) 2025 Nuvoton Technology Corp.
+ */
+
+#include <linux/i2c.h>
+#include <linux/idr.h>
+#include <linux/kernel.h>
+#include <linux/mfd/nct6694.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+/*
+ * USB command module type for NCT6694 I2C controller.
+ * This defines the module type used for communication with the NCT6694
+ * I2C controller over the USB interface.
+ */
+#define NCT6694_I2C_MOD 0x03
+
+/* Command 00h - I2C Deliver */
+#define NCT6694_I2C_DELIVER 0x00
+#define NCT6694_I2C_DELIVER_SEL 0x00
+
+#define NCT6694_I2C_MAX_DEVS 6
+
+static unsigned char br_reg[NCT6694_I2C_MAX_DEVS] = {[0 ... (NCT6694_I2C_MAX_DEVS - 1)] = 0xFF};
+
+module_param_array(br_reg, byte, NULL, 0644);
+MODULE_PARM_DESC(br_reg,
+ "I2C Baudrate register per adapter: (0=25K, 1=50K, 2=100K, 3=200K, 4=400K, 5=800K, 6=1M), default=2");
+
+enum nct6694_i2c_baudrate {
+ NCT6694_I2C_BR_25K = 0,
+ NCT6694_I2C_BR_50K,
+ NCT6694_I2C_BR_100K,
+ NCT6694_I2C_BR_200K,
+ NCT6694_I2C_BR_400K,
+ NCT6694_I2C_BR_800K,
+ NCT6694_I2C_BR_1M
+};
+
+struct __packed nct6694_i2c_deliver {
+ u8 port;
+ u8 br;
+ u8 addr;
+ u8 w_cnt;
+ u8 r_cnt;
+ u8 rsv[11];
+ u8 write_data[0x40];
+ u8 read_data[0x40];
+};
+
+struct nct6694_i2c_data {
+ struct device *dev;
+ struct nct6694 *nct6694;
+ struct i2c_adapter adapter;
+ struct nct6694_i2c_deliver deliver;
+ unsigned char port;
+ unsigned char br;
+};
+
+static DEFINE_IDA(nct6694_i2c_ida);
+
+static int nct6694_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+ struct nct6694_i2c_data *data = adap->algo_data;
+ struct nct6694_i2c_deliver *deliver = &data->deliver;
+ static const struct nct6694_cmd_header cmd_hd = {
+ .mod = NCT6694_I2C_MOD,
+ .cmd = NCT6694_I2C_DELIVER,
+ .sel = NCT6694_I2C_DELIVER_SEL,
+ .len = cpu_to_le16(sizeof(*deliver))
+ };
+ int ret, i;
+
+ for (i = 0; i < num; i++) {
+ struct i2c_msg *msg_temp = &msgs[i];
+
+ memset(deliver, 0, sizeof(*deliver));
+
+ if (msg_temp->len > 64)
+ return -EPROTO;
+
+ deliver->port = data->port;
+ deliver->br = data->br;
+ deliver->addr = i2c_8bit_addr_from_msg(msg_temp);
+ if (msg_temp->flags & I2C_M_RD) {
+ deliver->r_cnt = msg_temp->len;
+ ret = nct6694_write_msg(data->nct6694, &cmd_hd, deliver);
+ if (ret < 0)
+ return ret;
+
+ memcpy(msg_temp->buf, deliver->read_data, msg_temp->len);
+ } else {
+ deliver->w_cnt = msg_temp->len;
+ memcpy(deliver->write_data, msg_temp->buf, msg_temp->len);
+ ret = nct6694_write_msg(data->nct6694, &cmd_hd, deliver);
+ if (ret < 0)
+ return ret;
+ }
+ }
+
+ return num;
+}
+
+static u32 nct6694_func(struct i2c_adapter *adapter)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm algorithm = {
+ .master_xfer = nct6694_xfer,
+ .functionality = nct6694_func,
+};
+
+static int nct6694_i2c_set_baudrate(struct nct6694_i2c_data *data)
+{
+ if (data->port >= NCT6694_I2C_MAX_DEVS) {
+ dev_err(data->dev, "Invalid I2C port index %d\n", data->port);
+ return -EINVAL;
+ }
+
+ if (br_reg[data->port] > NCT6694_I2C_BR_1M) {
+ dev_warn(data->dev, "Invalid baudrate %d for I2C%d, using 100K\n",
+ br_reg[data->port], data->port);
+ br_reg[data->port] = NCT6694_I2C_BR_100K;
+ }
+
+ data->br = br_reg[data->port];
+
+ return 0;
+}
+
+static void nct6694_i2c_ida_remove(void *d)
+{
+ struct nct6694_i2c_data *data = d;
+
+ ida_free(&nct6694_i2c_ida, data->port);
+}
+
+static int nct6694_i2c_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct nct6694 *nct6694 = dev_get_drvdata(dev->parent);
+ struct nct6694_i2c_data *data;
+ int ret;
+
+ data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ data->dev = dev;
+ data->nct6694 = nct6694;
+
+ ret = ida_alloc(&nct6694_i2c_ida, GFP_KERNEL);
+ if (ret < 0)
+ return ret;
+ data->port = ret;
+
+ ret = devm_add_action_or_reset(dev, nct6694_i2c_ida_remove, data);
+ if (ret)
+ return ret;
+
+ ret = nct6694_i2c_set_baudrate(data);
+ if (ret)
+ return ret;
+
+ sprintf(data->adapter.name, "NCT6694 I2C Adapter %d", data->port);
+ data->adapter.owner = THIS_MODULE;
+ data->adapter.algo = &algorithm;
+ data->adapter.dev.parent = &pdev->dev;
+ data->adapter.algo_data = data;
+
+ platform_set_drvdata(pdev, data);
+
+ return devm_i2c_add_adapter(dev, &data->adapter);
+}
+
+static struct platform_driver nct6694_i2c_driver = {
+ .driver = {
+ .name = "nct6694-i2c",
+ },
+ .probe = nct6694_i2c_probe,
+};
+
+module_platform_driver(nct6694_i2c_driver);
+
+MODULE_DESCRIPTION("USB-I2C adapter driver for NCT6694");
+MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:nct6694-i2c");