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 */
 51struct 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
 84static const struct i2c_device_id mlxcpld_mux_id[] = {
 85	{ "mlxcpld_mux_module", 0 },
 86	{ }
 87};
 88MODULE_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 */
 93static 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
104static 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
120static 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 */
132static 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
174virt_reg_failed:
175	i2c_mux_del_adapters(muxc);
176	return err;
177}
178
179static 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
187static 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
196module_i2c_driver(mlxcpld_mux_driver);
197
198MODULE_AUTHOR("Michael Shych (michaels@mellanox.com)");
199MODULE_DESCRIPTION("Mellanox I2C-CPLD-MUX driver");
200MODULE_LICENSE("Dual BSD/GPL");
201MODULE_ALIAS("platform:i2c-mux-mlxcpld");