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 */
 23struct 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 */
 60static 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
 88static 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
106static 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 */
117static 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]);
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
168virt_reg_failed:
169	i2c_mux_del_adapters(muxc);
170	return err;
171}
172
173static 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
180static struct platform_driver mlxcpld_mux_driver = {
181	.driver = {
182		.name = "i2c-mux-mlxcpld",
183	},
184	.probe = mlxcpld_mux_probe,
185	.remove = mlxcpld_mux_remove,
186};
187
188module_platform_driver(mlxcpld_mux_driver);
189
190MODULE_AUTHOR("Michael Shych <michaels@mellanox.com>");
191MODULE_DESCRIPTION("Mellanox I2C-CPLD-MUX driver");
192MODULE_LICENSE("Dual BSD/GPL");
193MODULE_ALIAS("platform:i2c-mux-mlxcpld");