i2c-nct6694.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Nuvoton NCT6694 I2C adapter driver based on USB interface.
  4 *
  5 * Copyright (C) 2025 Nuvoton Technology Corp.
  6 */
  7
  8#include <linux/i2c.h>
  9#include <linux/idr.h>
 10#include <linux/kernel.h>
 11#include <linux/mfd/nct6694.h>
 12#include <linux/module.h>
 13#include <linux/platform_device.h>
 14
 15/*
 16 * USB command module type for NCT6694 I2C controller.
 17 * This defines the module type used for communication with the NCT6694
 18 * I2C controller over the USB interface.
 19 */
 20#define NCT6694_I2C_MOD			0x03
 21
 22/* Command 00h - I2C Deliver */
 23#define NCT6694_I2C_DELIVER		0x00
 24#define NCT6694_I2C_DELIVER_SEL		0x00
 25
 26#define NCT6694_I2C_MAX_XFER_SIZE	64
 27#define NCT6694_I2C_MAX_DEVS		6
 28
 29static unsigned char br_reg[NCT6694_I2C_MAX_DEVS] = {[0 ... (NCT6694_I2C_MAX_DEVS - 1)] = 0xFF};
 30
 31module_param_array(br_reg, byte, NULL, 0644);
 32MODULE_PARM_DESC(br_reg,
 33		 "I2C Baudrate register per adapter: (0=25K, 1=50K, 2=100K, 3=200K, 4=400K, 5=800K, 6=1M), default=2");
 34
 35enum nct6694_i2c_baudrate {
 36	NCT6694_I2C_BR_25K = 0,
 37	NCT6694_I2C_BR_50K,
 38	NCT6694_I2C_BR_100K,
 39	NCT6694_I2C_BR_200K,
 40	NCT6694_I2C_BR_400K,
 41	NCT6694_I2C_BR_800K,
 42	NCT6694_I2C_BR_1M
 43};
 44
 45struct __packed nct6694_i2c_deliver {
 46	u8 port;
 47	u8 br;
 48	u8 addr;
 49	u8 w_cnt;
 50	u8 r_cnt;
 51	u8 rsv[11];
 52	u8 write_data[NCT6694_I2C_MAX_XFER_SIZE];
 53	u8 read_data[NCT6694_I2C_MAX_XFER_SIZE];
 54};
 55
 56struct nct6694_i2c_data {
 57	struct device *dev;
 58	struct nct6694 *nct6694;
 59	struct i2c_adapter adapter;
 60	struct nct6694_i2c_deliver deliver;
 61	unsigned char port;
 62	unsigned char br;
 63};
 64
 65static int nct6694_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 66{
 67	struct nct6694_i2c_data *data = adap->algo_data;
 68	struct nct6694_i2c_deliver *deliver = &data->deliver;
 69	static const struct nct6694_cmd_header cmd_hd = {
 70		.mod = NCT6694_I2C_MOD,
 71		.cmd = NCT6694_I2C_DELIVER,
 72		.sel = NCT6694_I2C_DELIVER_SEL,
 73		.len = cpu_to_le16(sizeof(*deliver))
 74	};
 75	int ret, i;
 76
 77	for (i = 0; i < num; i++) {
 78		struct i2c_msg *msg_temp = &msgs[i];
 79
 80		memset(deliver, 0, sizeof(*deliver));
 81
 82		deliver->port = data->port;
 83		deliver->br = data->br;
 84		deliver->addr = i2c_8bit_addr_from_msg(msg_temp);
 85		if (msg_temp->flags & I2C_M_RD) {
 86			deliver->r_cnt = msg_temp->len;
 87			ret = nct6694_write_msg(data->nct6694, &cmd_hd, deliver);
 88			if (ret < 0)
 89				return ret;
 90
 91			memcpy(msg_temp->buf, deliver->read_data, msg_temp->len);
 92		} else {
 93			deliver->w_cnt = msg_temp->len;
 94			memcpy(deliver->write_data, msg_temp->buf, msg_temp->len);
 95			ret = nct6694_write_msg(data->nct6694, &cmd_hd, deliver);
 96			if (ret < 0)
 97				return ret;
 98		}
 99	}
100
101	return num;
102}
103
104static u32 nct6694_i2c_func(struct i2c_adapter *adapter)
105{
106	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
107}
108
109static const struct i2c_adapter_quirks nct6694_i2c_quirks = {
110	.max_read_len = NCT6694_I2C_MAX_XFER_SIZE,
111	.max_write_len = NCT6694_I2C_MAX_XFER_SIZE,
112};
113
114static const struct i2c_algorithm nct6694_i2c_algo = {
115	.xfer = nct6694_i2c_xfer,
116	.functionality = nct6694_i2c_func,
117};
118
119static int nct6694_i2c_set_baudrate(struct nct6694_i2c_data *data)
120{
121	if (data->port >= NCT6694_I2C_MAX_DEVS) {
122		dev_err(data->dev, "Invalid I2C port index %d\n", data->port);
123		return -EINVAL;
124	}
125
126	if (br_reg[data->port] > NCT6694_I2C_BR_1M) {
127		dev_warn(data->dev, "Invalid baudrate %d for I2C%d, using 100K\n",
128			 br_reg[data->port], data->port);
129		br_reg[data->port] = NCT6694_I2C_BR_100K;
130	}
131
132	data->br = br_reg[data->port];
133
134	return 0;
135}
136
137static void nct6694_i2c_ida_free(void *d)
138{
139	struct nct6694_i2c_data *data = d;
140	struct nct6694 *nct6694 = data->nct6694;
141
142	ida_free(&nct6694->i2c_ida, data->port);
143}
144
145static int nct6694_i2c_probe(struct platform_device *pdev)
146{
147	struct device *dev = &pdev->dev;
148	struct nct6694 *nct6694 = dev_get_drvdata(dev->parent);
149	struct nct6694_i2c_data *data;
150	int ret;
151
152	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
153	if (!data)
154		return -ENOMEM;
155
156	data->dev = dev;
157	data->nct6694 = nct6694;
158
159	ret = ida_alloc(&nct6694->i2c_ida, GFP_KERNEL);
160	if (ret < 0)
161		return ret;
162	data->port = ret;
163
164	ret = devm_add_action_or_reset(dev, nct6694_i2c_ida_free, data);
165	if (ret)
166		return ret;
167
168	ret = nct6694_i2c_set_baudrate(data);
169	if (ret)
170		return ret;
171
172	sprintf(data->adapter.name, "NCT6694 I2C Adapter %d", data->port);
173	data->adapter.owner = THIS_MODULE;
174	data->adapter.algo = &nct6694_i2c_algo;
175	data->adapter.quirks = &nct6694_i2c_quirks;
176	data->adapter.dev.parent = dev;
177	data->adapter.algo_data = data;
178
179	platform_set_drvdata(pdev, data);
180
181	return devm_i2c_add_adapter(dev, &data->adapter);
182}
183
184static struct platform_driver nct6694_i2c_driver = {
185	.driver = {
186		.name	= "nct6694-i2c",
187	},
188	.probe		= nct6694_i2c_probe,
189};
190
191module_platform_driver(nct6694_i2c_driver);
192
193MODULE_DESCRIPTION("USB-I2C adapter driver for NCT6694");
194MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
195MODULE_LICENSE("GPL");
196MODULE_ALIAS("platform:nct6694-i2c");