1 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
2 /*
3 * Mellanox i2c mux driver
4 *
5 * Copyright (C) 2016-2020 Mellanox Technologies
6 */
7
8 #include <linux/device.h>
9 #include <linux/i2c.h>
10 #include <linux/i2c-mux.h>
11 #include <linux/io.h>
12 #include <linux/init.h>
13 #include <linux/module.h>
14 #include <linux/platform_data/mlxcpld.h>
15 #include <linux/platform_device.h>
16 #include <linux/slab.h>
17
18 /* mlxcpld_mux - mux control structure:
19 * @last_val - last selected register value or -1 if mux deselected
20 * @client - I2C device client
21 * @pdata: platform data
22 */
23 struct mlxcpld_mux {
24 int last_val;
25 struct i2c_client *client;
26 struct mlxcpld_mux_plat_data pdata;
27 };
28
29 /* MUX logic description.
30 * Driver can support different mux control logic, according to CPLD
31 * implementation.
32 *
33 * Connectivity schema.
34 *
35 * i2c-mlxcpld Digital Analog
36 * driver
37 * *--------* * -> mux1 (virt bus2) -> mux -> |
38 * | I2CLPC | i2c physical * -> mux2 (virt bus3) -> mux -> |
39 * | bridge | bus 1 *---------* |
40 * | logic |---------------------> * mux reg * |
41 * | in CPLD| *---------* |
42 * *--------* i2c-mux-mlxpcld ^ * -> muxn (virt busn) -> mux -> |
43 * | driver | |
44 * | *---------------* | Devices
45 * | * CPLD (i2c bus)* select |
46 * | * registers for *--------*
47 * | * mux selection * deselect
48 * | *---------------*
49 * | |
50 * <--------> <----------->
51 * i2c cntrl Board cntrl reg
52 * reg space space (mux select,
53 * IO, LED, WD, info)
54 *
55 */
56
57 /* Write to mux register. Don't use i2c_transfer() and i2c_smbus_xfer()
58 * for this as they will try to lock adapter a second time.
59 */
mlxcpld_mux_reg_write(struct i2c_adapter * adap,struct mlxcpld_mux * mux,u32 val)60 static int mlxcpld_mux_reg_write(struct i2c_adapter *adap,
61 struct mlxcpld_mux *mux, u32 val)
62 {
63 struct i2c_client *client = mux->client;
64 union i2c_smbus_data data;
65 struct i2c_msg msg;
66 u8 buf[3];
67
68 switch (mux->pdata.reg_size) {
69 case 1:
70 data.byte = val;
71 return __i2c_smbus_xfer(adap, client->addr, client->flags,
72 I2C_SMBUS_WRITE, mux->pdata.sel_reg_addr,
73 I2C_SMBUS_BYTE_DATA, &data);
74 case 2:
75 buf[0] = mux->pdata.sel_reg_addr >> 8;
76 buf[1] = mux->pdata.sel_reg_addr;
77 buf[2] = val;
78 msg.addr = client->addr;
79 msg.buf = buf;
80 msg.len = mux->pdata.reg_size + 1;
81 msg.flags = 0;
82 return __i2c_transfer(adap, &msg, 1);
83 default:
84 return -EINVAL;
85 }
86 }
87
mlxcpld_mux_select_chan(struct i2c_mux_core * muxc,u32 chan)88 static int mlxcpld_mux_select_chan(struct i2c_mux_core *muxc, u32 chan)
89 {
90 struct mlxcpld_mux *mux = i2c_mux_priv(muxc);
91 u32 regval = chan;
92 int err = 0;
93
94 if (mux->pdata.reg_size == 1)
95 regval += 1;
96
97 /* Only select the channel if its different from the last channel */
98 if (mux->last_val != regval) {
99 err = mlxcpld_mux_reg_write(muxc->parent, mux, regval);
100 mux->last_val = err < 0 ? -1 : regval;
101 }
102
103 return err;
104 }
105
mlxcpld_mux_deselect(struct i2c_mux_core * muxc,u32 chan)106 static int mlxcpld_mux_deselect(struct i2c_mux_core *muxc, u32 chan)
107 {
108 struct mlxcpld_mux *mux = i2c_mux_priv(muxc);
109
110 /* Deselect active channel */
111 mux->last_val = -1;
112
113 return mlxcpld_mux_reg_write(muxc->parent, mux, 0);
114 }
115
116 /* Probe/reomove functions */
mlxcpld_mux_probe(struct platform_device * pdev)117 static int mlxcpld_mux_probe(struct platform_device *pdev)
118 {
119 struct mlxcpld_mux_plat_data *pdata = dev_get_platdata(&pdev->dev);
120 struct i2c_client *client = to_i2c_client(pdev->dev.parent);
121 struct i2c_mux_core *muxc;
122 struct mlxcpld_mux *data;
123 int num, err;
124 u32 func;
125
126 if (!pdata)
127 return -EINVAL;
128
129 switch (pdata->reg_size) {
130 case 1:
131 func = I2C_FUNC_SMBUS_WRITE_BYTE_DATA;
132 break;
133 case 2:
134 func = I2C_FUNC_I2C;
135 break;
136 default:
137 return -EINVAL;
138 }
139
140 if (!i2c_check_functionality(client->adapter, func))
141 return -ENODEV;
142
143 muxc = i2c_mux_alloc(client->adapter, &pdev->dev, pdata->num_adaps,
144 sizeof(*data), 0, mlxcpld_mux_select_chan,
145 mlxcpld_mux_deselect);
146 if (!muxc)
147 return -ENOMEM;
148
149 platform_set_drvdata(pdev, muxc);
150 data = i2c_mux_priv(muxc);
151 data->client = client;
152 memcpy(&data->pdata, pdata, sizeof(*pdata));
153 data->last_val = -1; /* force the first selection */
154
155 /* Create an adapter for each channel. */
156 for (num = 0; num < pdata->num_adaps; num++) {
157 err = i2c_mux_add_adapter(muxc, 0, pdata->chan_ids[num], 0);
158 if (err)
159 goto virt_reg_failed;
160 }
161
162 /* Notify caller when all channels' adapters are created. */
163 if (pdata->completion_notify)
164 pdata->completion_notify(pdata->handle, muxc->parent, muxc->adapter);
165
166 return 0;
167
168 virt_reg_failed:
169 i2c_mux_del_adapters(muxc);
170 return err;
171 }
172
mlxcpld_mux_remove(struct platform_device * pdev)173 static void mlxcpld_mux_remove(struct platform_device *pdev)
174 {
175 struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
176
177 i2c_mux_del_adapters(muxc);
178 }
179
180 static struct platform_driver mlxcpld_mux_driver = {
181 .driver = {
182 .name = "i2c-mux-mlxcpld",
183 },
184 .probe = mlxcpld_mux_probe,
185 .remove_new = mlxcpld_mux_remove,
186 };
187
188 module_platform_driver(mlxcpld_mux_driver);
189
190 MODULE_AUTHOR("Michael Shych (michaels@mellanox.com)");
191 MODULE_DESCRIPTION("Mellanox I2C-CPLD-MUX driver");
192 MODULE_LICENSE("Dual BSD/GPL");
193 MODULE_ALIAS("platform:i2c-mux-mlxcpld");
194