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
29 static unsigned char br_reg[NCT6694_I2C_MAX_DEVS] = {[0 ... (NCT6694_I2C_MAX_DEVS - 1)] = 0xFF};
30
31 module_param_array(br_reg, byte, NULL, 0644);
32 MODULE_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
35 enum 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
45 struct __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
56 struct 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
nct6694_i2c_xfer(struct i2c_adapter * adap,struct i2c_msg * msgs,int num)65 static 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
nct6694_i2c_func(struct i2c_adapter * adapter)104 static u32 nct6694_i2c_func(struct i2c_adapter *adapter)
105 {
106 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
107 }
108
109 static 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
114 static const struct i2c_algorithm nct6694_i2c_algo = {
115 .xfer = nct6694_i2c_xfer,
116 .functionality = nct6694_i2c_func,
117 };
118
nct6694_i2c_set_baudrate(struct nct6694_i2c_data * data)119 static 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
nct6694_i2c_ida_free(void * d)137 static 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
nct6694_i2c_probe(struct platform_device * pdev)145 static 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
184 static struct platform_driver nct6694_i2c_driver = {
185 .driver = {
186 .name = "nct6694-i2c",
187 },
188 .probe = nct6694_i2c_probe,
189 };
190
191 module_platform_driver(nct6694_i2c_driver);
192
193 MODULE_DESCRIPTION("USB-I2C adapter driver for NCT6694");
194 MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
195 MODULE_LICENSE("GPL");
196 MODULE_ALIAS("platform:nct6694-i2c");
197