summaryrefslogtreecommitdiffstats
path: root/drivers/i2c/muxes/i2c-mux-mlxcpld.c
blob: 4c6ed1d58c79a311bee5634bd6d7fbc6140676d3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
/*
 * Mellanox i2c mux driver
 *
 * Copyright (C) 2016-2020 Mellanox Technologies
 */

#include <linux/device.h>
#include <linux/i2c.h>
#include <linux/i2c-mux.h>
#include <linux/io.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_data/mlxcpld.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

/* mlxcpld_mux - mux control structure:
 * @last_val - last selected register value or -1 if mux deselected
 * @client - I2C device client
 * @pdata: platform data
 */
struct mlxcpld_mux {
	int last_val;
	struct i2c_client *client;
	struct mlxcpld_mux_plat_data pdata;
};

/* MUX logic description.
 * Driver can support different mux control logic, according to CPLD
 * implementation.
 *
 * Connectivity schema.
 *
 * i2c-mlxcpld                                 Digital               Analog
 * driver
 * *--------*                                 * -> mux1 (virt bus2) -> mux -> |
 * | I2CLPC | i2c physical                    * -> mux2 (virt bus3) -> mux -> |
 * | bridge | bus 1                 *---------*                               |
 * | logic  |---------------------> * mux reg *                               |
 * | in CPLD|                       *---------*                               |
 * *--------*   i2c-mux-mlxpcld          ^    * -> muxn (virt busn) -> mux -> |
 *     |        driver                   |                                    |
 *     |        *---------------*        |                              Devices
 *     |        * CPLD (i2c bus)* select |
 *     |        * registers for *--------*
 *     |        * mux selection * deselect
 *     |        *---------------*
 *     |                 |
 * <-------->     <----------->
 * i2c cntrl      Board cntrl reg
 * reg space      space (mux select,
 *                IO, LED, WD, info)
 *
 */

/* Write to mux register. Don't use i2c_transfer() and i2c_smbus_xfer()
 * for this as they will try to lock adapter a second time.
 */
static int mlxcpld_mux_reg_write(struct i2c_adapter *adap,
				 struct mlxcpld_mux *mux, u32 val)
{
	struct i2c_client *client = mux->client;
	union i2c_smbus_data data;
	struct i2c_msg msg;
	u8 buf[3];

	switch (mux->pdata.reg_size) {
	case 1:
		data.byte = val;
		return __i2c_smbus_xfer(adap, client->addr, client->flags,
					I2C_SMBUS_WRITE, mux->pdata.sel_reg_addr,
					I2C_SMBUS_BYTE_DATA, &data);
	case 2:
		buf[0] = mux->pdata.sel_reg_addr >> 8;
		buf[1] = mux->pdata.sel_reg_addr;
		buf[2] = val;
		msg.addr = client->addr;
		msg.buf = buf;
		msg.len = mux->pdata.reg_size + 1;
		msg.flags = 0;
		return __i2c_transfer(adap, &msg, 1);
	default:
		return -EINVAL;
	}
}

static int mlxcpld_mux_select_chan(struct i2c_mux_core *muxc, u32 chan)
{
	struct mlxcpld_mux *mux = i2c_mux_priv(muxc);
	u32 regval = chan;
	int err = 0;

	if (mux->pdata.reg_size == 1)
		regval += 1;

	/* Only select the channel if its different from the last channel */
	if (mux->last_val != regval) {
		err = mlxcpld_mux_reg_write(muxc->parent, mux, regval);
		mux->last_val = err < 0 ? -1 : regval;
	}

	return err;
}

static int mlxcpld_mux_deselect(struct i2c_mux_core *muxc, u32 chan)
{
	struct mlxcpld_mux *mux = i2c_mux_priv(muxc);

	/* Deselect active channel */
	mux->last_val = -1;

	return mlxcpld_mux_reg_write(muxc->parent, mux, 0);
}

/* Probe/reomove functions */
static int mlxcpld_mux_probe(struct platform_device *pdev)
{
	struct mlxcpld_mux_plat_data *pdata = dev_get_platdata(&pdev->dev);
	struct i2c_client *client = to_i2c_client(pdev->dev.parent);
	struct i2c_mux_core *muxc;
	struct mlxcpld_mux *data;
	int num, err;
	u32 func;

	if (!pdata)
		return -EINVAL;

	switch (pdata->reg_size) {
	case 1:
		func = I2C_FUNC_SMBUS_WRITE_BYTE_DATA;
		break;
	case 2:
		func = I2C_FUNC_I2C;
		break;
	default:
		return -EINVAL;
	}

	if (!i2c_check_functionality(client->adapter, func))
		return -ENODEV;

	muxc = i2c_mux_alloc(client->adapter, &pdev->dev, pdata->num_adaps,
			     sizeof(*data), 0, mlxcpld_mux_select_chan,
			     mlxcpld_mux_deselect);
	if (!muxc)
		return -ENOMEM;

	platform_set_drvdata(pdev, muxc);
	data = i2c_mux_priv(muxc);
	data->client = client;
	memcpy(&data->pdata, pdata, sizeof(*pdata));
	data->last_val = -1; /* force the first selection */

	/* Create an adapter for each channel. */
	for (num = 0; num < pdata->num_adaps; num++) {
		err = i2c_mux_add_adapter(muxc, 0, pdata->chan_ids[num], 0);
		if (err)
			goto virt_reg_failed;
	}

	/* Notify caller when all channels' adapters are created. */
	if (pdata->completion_notify)
		pdata->completion_notify(pdata->handle, muxc->parent, muxc->adapter);

	return 0;

virt_reg_failed:
	i2c_mux_del_adapters(muxc);
	return err;
}

static void mlxcpld_mux_remove(struct platform_device *pdev)
{
	struct i2c_mux_core *muxc = platform_get_drvdata(pdev);

	i2c_mux_del_adapters(muxc);
}

static struct platform_driver mlxcpld_mux_driver = {
	.driver = {
		.name = "i2c-mux-mlxcpld",
	},
	.probe = mlxcpld_mux_probe,
	.remove_new = mlxcpld_mux_remove,
};

module_platform_driver(mlxcpld_mux_driver);

MODULE_AUTHOR("Michael Shych <michaels@mellanox.com>");
MODULE_DESCRIPTION("Mellanox I2C-CPLD-MUX driver");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_ALIAS("platform:i2c-mux-mlxcpld");