1 /*
2 * drivers/i2c/muxes/i2c-mux-mlxcpld.c
3 * Copyright (c) 2016 Mellanox Technologies. All rights reserved.
4 * Copyright (c) 2016 Michael Shych <michaels@mellanox.com>
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the names of the copyright holders nor the names of its
15 * contributors may be used to endorse or promote products derived from
16 * this software without specific prior written permission.
17 *
18 * Alternatively, this software may be distributed under the terms of the
19 * GNU General Public License ("GPL") version 2 as published by the Free
20 * Software Foundation.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
23 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
26 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
27 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
28 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
29 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
30 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
31 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
32 * POSSIBILITY OF SUCH DAMAGE.
33 */
34
35 #include <linux/device.h>
36 #include <linux/i2c.h>
37 #include <linux/i2c-mux.h>
38 #include <linux/io.h>
39 #include <linux/init.h>
40 #include <linux/module.h>
41 #include <linux/platform_data/x86/mlxcpld.h>
42 #include <linux/platform_device.h>
43 #include <linux/slab.h>
44
45 #define CPLD_MUX_MAX_NCHANS 8
46
47 /* mlxcpld_mux - mux control structure:
48 * @last_chan - last register value
49 * @client - I2C device client
50 */
51 struct mlxcpld_mux {
52 u8 last_chan;
53 struct i2c_client *client;
54 };
55
56 /* MUX logic description.
57 * Driver can support different mux control logic, according to CPLD
58 * implementation.
59 *
60 * Connectivity schema.
61 *
62 * i2c-mlxcpld Digital Analog
63 * driver
64 * *--------* * -> mux1 (virt bus2) -> mux -> |
65 * | I2CLPC | i2c physical * -> mux2 (virt bus3) -> mux -> |
66 * | bridge | bus 1 *---------* |
67 * | logic |---------------------> * mux reg * |
68 * | in CPLD| *---------* |
69 * *--------* i2c-mux-mlxpcld ^ * -> muxn (virt busn) -> mux -> |
70 * | driver | |
71 * | *---------------* | Devices
72 * | * CPLD (i2c bus)* select |
73 * | * registers for *--------*
74 * | * mux selection * deselect
75 * | *---------------*
76 * | |
77 * <--------> <----------->
78 * i2c cntrl Board cntrl reg
79 * reg space space (mux select,
80 * IO, LED, WD, info)
81 *
82 */
83
84 static const struct i2c_device_id mlxcpld_mux_id[] = {
85 { "mlxcpld_mux_module", 0 },
86 { }
87 };
88 MODULE_DEVICE_TABLE(i2c, mlxcpld_mux_id);
89
90 /* Write to mux register. Don't use i2c_transfer() and i2c_smbus_xfer()
91 * for this as they will try to lock adapter a second time.
92 */
93 static int mlxcpld_mux_reg_write(struct i2c_adapter *adap,
94 struct i2c_client *client, u8 val)
95 {
96 struct mlxcpld_mux_plat_data *pdata = dev_get_platdata(&client->dev);
97 union i2c_smbus_data data = { .byte = val };
98
99 return __i2c_smbus_xfer(adap, client->addr, client->flags,
100 I2C_SMBUS_WRITE, pdata->sel_reg_addr,
101 I2C_SMBUS_BYTE_DATA, &data);
102 }
103
104 static int mlxcpld_mux_select_chan(struct i2c_mux_core *muxc, u32 chan)
105 {
106 struct mlxcpld_mux *data = i2c_mux_priv(muxc);
107 struct i2c_client *client = data->client;
108 u8 regval = chan + 1;
109 int err = 0;
110
111 /* Only select the channel if its different from the last channel */
112 if (data->last_chan != regval) {
113 err = mlxcpld_mux_reg_write(muxc->parent, client, regval);
114 data->last_chan = err < 0 ? 0 : regval;
115 }
116
117 return err;
118 }
119
120 static int mlxcpld_mux_deselect(struct i2c_mux_core *muxc, u32 chan)
121 {
122 struct mlxcpld_mux *data = i2c_mux_priv(muxc);
123 struct i2c_client *client = data->client;
124
125 /* Deselect active channel */
126 data->last_chan = 0;
127
128 return mlxcpld_mux_reg_write(muxc->parent, client, data->last_chan);
129 }
130
131 /* Probe/reomove functions */
132 static int mlxcpld_mux_probe(struct i2c_client *client,
133 const struct i2c_device_id *id)
134 {
135 struct i2c_adapter *adap = client->adapter;
136 struct mlxcpld_mux_plat_data *pdata = dev_get_platdata(&client->dev);
137 struct i2c_mux_core *muxc;
138 int num, force;
139 struct mlxcpld_mux *data;
140 int err;
141
142 if (!pdata)
143 return -EINVAL;
144
145 if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
146 return -ENODEV;
147
148 muxc = i2c_mux_alloc(adap, &client->dev, CPLD_MUX_MAX_NCHANS,
149 sizeof(*data), 0, mlxcpld_mux_select_chan,
150 mlxcpld_mux_deselect);
151 if (!muxc)
152 return -ENOMEM;
153
154 data = i2c_mux_priv(muxc);
155 i2c_set_clientdata(client, muxc);
156 data->client = client;
157 data->last_chan = 0; /* force the first selection */
158
159 /* Create an adapter for each channel. */
160 for (num = 0; num < CPLD_MUX_MAX_NCHANS; num++) {
161 if (num >= pdata->num_adaps)
162 /* discard unconfigured channels */
163 break;
164
165 force = pdata->adap_ids[num];
166
167 err = i2c_mux_add_adapter(muxc, force, num, 0);
168 if (err)
169 goto virt_reg_failed;
170 }
171
172 return 0;
173
174 virt_reg_failed:
175 i2c_mux_del_adapters(muxc);
176 return err;
177 }
178
179 static int mlxcpld_mux_remove(struct i2c_client *client)
180 {
181 struct i2c_mux_core *muxc = i2c_get_clientdata(client);
182
183 i2c_mux_del_adapters(muxc);
184 return 0;
185 }
186
187 static struct i2c_driver mlxcpld_mux_driver = {
188 .driver = {
189 .name = "mlxcpld-mux",
190 },
191 .probe = mlxcpld_mux_probe,
192 .remove = mlxcpld_mux_remove,
193 .id_table = mlxcpld_mux_id,
194 };
195
196 module_i2c_driver(mlxcpld_mux_driver);
197
198 MODULE_AUTHOR("Michael Shych (michaels@mellanox.com)");
199 MODULE_DESCRIPTION("Mellanox I2C-CPLD-MUX driver");
200 MODULE_LICENSE("Dual BSD/GPL");
201 MODULE_ALIAS("platform:i2c-mux-mlxcpld");