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_device.h>
 42#include <linux/slab.h>
 43#include <linux/version.h>
 44#include <linux/i2c/mlxcpld.h>
 45
 46#define CPLD_MUX_MAX_NCHANS	8
 47
 48/* mlxcpld_mux - mux control structure:
 49 * @last_chan - last register value
 50 * @client - I2C device client
 51 */
 52struct mlxcpld_mux {
 53	u8 last_chan;
 54	struct i2c_client *client;
 55};
 56
 57/* MUX logic description.
 58 * Driver can support different mux control logic, according to CPLD
 59 * implementation.
 60 *
 61 * Connectivity schema.
 62 *
 63 * i2c-mlxcpld                                 Digital               Analog
 64 * driver
 65 * *--------*                                 * -> mux1 (virt bus2) -> mux -> |
 66 * | I2CLPC | i2c physical                    * -> mux2 (virt bus3) -> mux -> |
 67 * | bridge | bus 1                 *---------*                               |
 68 * | logic  |---------------------> * mux reg *                               |
 69 * | in CPLD|                       *---------*                               |
 70 * *--------*   i2c-mux-mlxpcld          ^    * -> muxn (virt busn) -> mux -> |
 71 *     |        driver                   |                                    |
 72 *     |        *---------------*        |                              Devices
 73 *     |        * CPLD (i2c bus)* select |
 74 *     |        * registers for *--------*
 75 *     |        * mux selection * deselect
 76 *     |        *---------------*
 77 *     |                 |
 78 * <-------->     <----------->
 79 * i2c cntrl      Board cntrl reg
 80 * reg space      space (mux select,
 81 *                IO, LED, WD, info)
 82 *
 83 */
 84
 85static const struct i2c_device_id mlxcpld_mux_id[] = {
 86	{ "mlxcpld_mux_module", 0 },
 87	{ }
 88};
 89MODULE_DEVICE_TABLE(i2c, mlxcpld_mux_id);
 90
 91/* Write to mux register. Don't use i2c_transfer() and i2c_smbus_xfer()
 92 * for this as they will try to lock adapter a second time.
 93 */
 94static int mlxcpld_mux_reg_write(struct i2c_adapter *adap,
 95				 struct i2c_client *client, u8 val)
 96{
 97	struct mlxcpld_mux_plat_data *pdata = dev_get_platdata(&client->dev);
 98	int ret = -ENODEV;
 99
100	if (adap->algo->master_xfer) {
101		struct i2c_msg msg;
102		u8 msgbuf[] = {pdata->sel_reg_addr, val};
103
104		msg.addr = client->addr;
105		msg.flags = 0;
106		msg.len = 2;
107		msg.buf = msgbuf;
108		ret = __i2c_transfer(adap, &msg, 1);
109
110		if (ret >= 0 && ret != 1)
111			ret = -EREMOTEIO;
112	} else if (adap->algo->smbus_xfer) {
113		union i2c_smbus_data data;
114
115		data.byte = val;
116		ret = adap->algo->smbus_xfer(adap, client->addr,
117					     client->flags, I2C_SMBUS_WRITE,
118					     pdata->sel_reg_addr,
119					     I2C_SMBUS_BYTE_DATA, &data);
120	}
121
122	return ret;
123}
124
125static int mlxcpld_mux_select_chan(struct i2c_mux_core *muxc, u32 chan)
126{
127	struct mlxcpld_mux *data = i2c_mux_priv(muxc);
128	struct i2c_client *client = data->client;
129	u8 regval = chan + 1;
130	int err = 0;
131
132	/* Only select the channel if its different from the last channel */
133	if (data->last_chan != regval) {
134		err = mlxcpld_mux_reg_write(muxc->parent, client, regval);
135		data->last_chan = err < 0 ? 0 : regval;
136	}
137
138	return err;
139}
140
141static int mlxcpld_mux_deselect(struct i2c_mux_core *muxc, u32 chan)
142{
143	struct mlxcpld_mux *data = i2c_mux_priv(muxc);
144	struct i2c_client *client = data->client;
145
146	/* Deselect active channel */
147	data->last_chan = 0;
148
149	return mlxcpld_mux_reg_write(muxc->parent, client, data->last_chan);
150}
151
152/* Probe/reomove functions */
153static int mlxcpld_mux_probe(struct i2c_client *client,
154			     const struct i2c_device_id *id)
155{
156	struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
157	struct mlxcpld_mux_plat_data *pdata = dev_get_platdata(&client->dev);
158	struct i2c_mux_core *muxc;
159	int num, force;
160	struct mlxcpld_mux *data;
161	int err;
162
163	if (!pdata)
164		return -EINVAL;
165
166	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
167		return -ENODEV;
168
169	muxc = i2c_mux_alloc(adap, &client->dev, CPLD_MUX_MAX_NCHANS,
170			     sizeof(*data), 0, mlxcpld_mux_select_chan,
171			     mlxcpld_mux_deselect);
172	if (!muxc)
173		return -ENOMEM;
174
175	data = i2c_mux_priv(muxc);
176	i2c_set_clientdata(client, muxc);
177	data->client = client;
178	data->last_chan = 0; /* force the first selection */
179
180	/* Create an adapter for each channel. */
181	for (num = 0; num < CPLD_MUX_MAX_NCHANS; num++) {
182		if (num >= pdata->num_adaps)
183			/* discard unconfigured channels */
184			break;
185
186		force = pdata->adap_ids[num];
187
188		err = i2c_mux_add_adapter(muxc, force, num, 0);
189		if (err)
190			goto virt_reg_failed;
191	}
192
193	return 0;
194
195virt_reg_failed:
196	i2c_mux_del_adapters(muxc);
197	return err;
198}
199
200static int mlxcpld_mux_remove(struct i2c_client *client)
201{
202	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
203
204	i2c_mux_del_adapters(muxc);
205	return 0;
206}
207
208static struct i2c_driver mlxcpld_mux_driver = {
209	.driver		= {
210		.name	= "mlxcpld-mux",
211	},
212	.probe		= mlxcpld_mux_probe,
213	.remove		= mlxcpld_mux_remove,
214	.id_table	= mlxcpld_mux_id,
215};
216
217module_i2c_driver(mlxcpld_mux_driver);
218
219MODULE_AUTHOR("Michael Shych (michaels@mellanox.com)");
220MODULE_DESCRIPTION("Mellanox I2C-CPLD-MUX driver");
221MODULE_LICENSE("Dual BSD/GPL");
222MODULE_ALIAS("platform:i2c-mux-mlxcpld");