Loading...
1/*
2 * I2C multiplexer using a single register
3 *
4 * Copyright 2015 Freescale Semiconductor
5 * York Sun <yorksun@freescale.com>
6 *
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License as published by the
9 * Free Software Foundation; either version 2 of the License, or (at your
10 * option) any later version.
11 */
12
13#include <linux/i2c.h>
14#include <linux/i2c-mux.h>
15#include <linux/init.h>
16#include <linux/io.h>
17#include <linux/module.h>
18#include <linux/of_address.h>
19#include <linux/platform_data/i2c-mux-reg.h>
20#include <linux/platform_device.h>
21#include <linux/slab.h>
22
23struct regmux {
24 struct i2c_adapter *parent;
25 struct i2c_adapter **adap; /* child busses */
26 struct i2c_mux_reg_platform_data data;
27};
28
29static int i2c_mux_reg_set(const struct regmux *mux, unsigned int chan_id)
30{
31 if (!mux->data.reg)
32 return -EINVAL;
33
34 /*
35 * Write to the register, followed by a read to ensure the write is
36 * completed on a "posted" bus, for example PCI or write buffers.
37 * The endianness of reading doesn't matter and the return data
38 * is not used.
39 */
40 switch (mux->data.reg_size) {
41 case 4:
42 if (mux->data.little_endian)
43 iowrite32(chan_id, mux->data.reg);
44 else
45 iowrite32be(chan_id, mux->data.reg);
46 if (!mux->data.write_only)
47 ioread32(mux->data.reg);
48 break;
49 case 2:
50 if (mux->data.little_endian)
51 iowrite16(chan_id, mux->data.reg);
52 else
53 iowrite16be(chan_id, mux->data.reg);
54 if (!mux->data.write_only)
55 ioread16(mux->data.reg);
56 break;
57 case 1:
58 iowrite8(chan_id, mux->data.reg);
59 if (!mux->data.write_only)
60 ioread8(mux->data.reg);
61 break;
62 }
63
64 return 0;
65}
66
67static int i2c_mux_reg_select(struct i2c_adapter *adap, void *data,
68 unsigned int chan)
69{
70 struct regmux *mux = data;
71
72 return i2c_mux_reg_set(mux, chan);
73}
74
75static int i2c_mux_reg_deselect(struct i2c_adapter *adap, void *data,
76 unsigned int chan)
77{
78 struct regmux *mux = data;
79
80 if (mux->data.idle_in_use)
81 return i2c_mux_reg_set(mux, mux->data.idle);
82
83 return 0;
84}
85
86#ifdef CONFIG_OF
87static int i2c_mux_reg_probe_dt(struct regmux *mux,
88 struct platform_device *pdev)
89{
90 struct device_node *np = pdev->dev.of_node;
91 struct device_node *adapter_np, *child;
92 struct i2c_adapter *adapter;
93 struct resource res;
94 unsigned *values;
95 int i = 0;
96
97 if (!np)
98 return -ENODEV;
99
100 adapter_np = of_parse_phandle(np, "i2c-parent", 0);
101 if (!adapter_np) {
102 dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
103 return -ENODEV;
104 }
105 adapter = of_find_i2c_adapter_by_node(adapter_np);
106 of_node_put(adapter_np);
107 if (!adapter)
108 return -EPROBE_DEFER;
109
110 mux->parent = adapter;
111 mux->data.parent = i2c_adapter_id(adapter);
112 put_device(&adapter->dev);
113
114 mux->data.n_values = of_get_child_count(np);
115 if (of_find_property(np, "little-endian", NULL)) {
116 mux->data.little_endian = true;
117 } else if (of_find_property(np, "big-endian", NULL)) {
118 mux->data.little_endian = false;
119 } else {
120#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : \
121 defined(__LITTLE_ENDIAN)
122 mux->data.little_endian = true;
123#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : \
124 defined(__BIG_ENDIAN)
125 mux->data.little_endian = false;
126#else
127#error Endianness not defined?
128#endif
129 }
130 if (of_find_property(np, "write-only", NULL))
131 mux->data.write_only = true;
132 else
133 mux->data.write_only = false;
134
135 values = devm_kzalloc(&pdev->dev,
136 sizeof(*mux->data.values) * mux->data.n_values,
137 GFP_KERNEL);
138 if (!values) {
139 dev_err(&pdev->dev, "Cannot allocate values array");
140 return -ENOMEM;
141 }
142
143 for_each_child_of_node(np, child) {
144 of_property_read_u32(child, "reg", values + i);
145 i++;
146 }
147 mux->data.values = values;
148
149 if (!of_property_read_u32(np, "idle-state", &mux->data.idle))
150 mux->data.idle_in_use = true;
151
152 /* map address from "reg" if exists */
153 if (of_address_to_resource(np, 0, &res)) {
154 mux->data.reg_size = resource_size(&res);
155 mux->data.reg = devm_ioremap_resource(&pdev->dev, &res);
156 if (IS_ERR(mux->data.reg))
157 return PTR_ERR(mux->data.reg);
158 }
159
160 return 0;
161}
162#else
163static int i2c_mux_reg_probe_dt(struct regmux *mux,
164 struct platform_device *pdev)
165{
166 return 0;
167}
168#endif
169
170static int i2c_mux_reg_probe(struct platform_device *pdev)
171{
172 struct regmux *mux;
173 struct i2c_adapter *parent;
174 struct resource *res;
175 int (*deselect)(struct i2c_adapter *, void *, u32);
176 unsigned int class;
177 int i, ret, nr;
178
179 mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
180 if (!mux)
181 return -ENOMEM;
182
183 platform_set_drvdata(pdev, mux);
184
185 if (dev_get_platdata(&pdev->dev)) {
186 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
187 sizeof(mux->data));
188
189 parent = i2c_get_adapter(mux->data.parent);
190 if (!parent)
191 return -EPROBE_DEFER;
192
193 mux->parent = parent;
194 } else {
195 ret = i2c_mux_reg_probe_dt(mux, pdev);
196 if (ret < 0) {
197 dev_err(&pdev->dev, "Error parsing device tree");
198 return ret;
199 }
200 }
201
202 if (!mux->data.reg) {
203 dev_info(&pdev->dev,
204 "Register not set, using platform resource\n");
205 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
206 mux->data.reg_size = resource_size(res);
207 mux->data.reg = devm_ioremap_resource(&pdev->dev, res);
208 if (IS_ERR(mux->data.reg))
209 return PTR_ERR(mux->data.reg);
210 }
211
212 if (mux->data.reg_size != 4 && mux->data.reg_size != 2 &&
213 mux->data.reg_size != 1) {
214 dev_err(&pdev->dev, "Invalid register size\n");
215 return -EINVAL;
216 }
217
218 mux->adap = devm_kzalloc(&pdev->dev,
219 sizeof(*mux->adap) * mux->data.n_values,
220 GFP_KERNEL);
221 if (!mux->adap) {
222 dev_err(&pdev->dev, "Cannot allocate i2c_adapter structure");
223 return -ENOMEM;
224 }
225
226 if (mux->data.idle_in_use)
227 deselect = i2c_mux_reg_deselect;
228 else
229 deselect = NULL;
230
231 for (i = 0; i < mux->data.n_values; i++) {
232 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
233 class = mux->data.classes ? mux->data.classes[i] : 0;
234
235 mux->adap[i] = i2c_add_mux_adapter(mux->parent, &pdev->dev, mux,
236 nr, mux->data.values[i],
237 class, i2c_mux_reg_select,
238 deselect);
239 if (!mux->adap[i]) {
240 ret = -ENODEV;
241 dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
242 goto add_adapter_failed;
243 }
244 }
245
246 dev_dbg(&pdev->dev, "%d port mux on %s adapter\n",
247 mux->data.n_values, mux->parent->name);
248
249 return 0;
250
251add_adapter_failed:
252 for (; i > 0; i--)
253 i2c_del_mux_adapter(mux->adap[i - 1]);
254
255 return ret;
256}
257
258static int i2c_mux_reg_remove(struct platform_device *pdev)
259{
260 struct regmux *mux = platform_get_drvdata(pdev);
261 int i;
262
263 for (i = 0; i < mux->data.n_values; i++)
264 i2c_del_mux_adapter(mux->adap[i]);
265
266 i2c_put_adapter(mux->parent);
267
268 return 0;
269}
270
271static const struct of_device_id i2c_mux_reg_of_match[] = {
272 { .compatible = "i2c-mux-reg", },
273 {},
274};
275MODULE_DEVICE_TABLE(of, i2c_mux_reg_of_match);
276
277static struct platform_driver i2c_mux_reg_driver = {
278 .probe = i2c_mux_reg_probe,
279 .remove = i2c_mux_reg_remove,
280 .driver = {
281 .name = "i2c-mux-reg",
282 },
283};
284
285module_platform_driver(i2c_mux_reg_driver);
286
287MODULE_DESCRIPTION("Register-based I2C multiplexer driver");
288MODULE_AUTHOR("York Sun <yorksun@freescale.com>");
289MODULE_LICENSE("GPL");
290MODULE_ALIAS("platform:i2c-mux-reg");
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * I2C multiplexer using a single register
4 *
5 * Copyright 2015 Freescale Semiconductor
6 * York Sun <yorksun@freescale.com>
7 */
8
9#include <linux/i2c.h>
10#include <linux/i2c-mux.h>
11#include <linux/init.h>
12#include <linux/io.h>
13#include <linux/module.h>
14#include <linux/of_address.h>
15#include <linux/platform_data/i2c-mux-reg.h>
16#include <linux/platform_device.h>
17#include <linux/slab.h>
18
19struct regmux {
20 struct i2c_mux_reg_platform_data data;
21};
22
23static int i2c_mux_reg_set(const struct regmux *mux, unsigned int chan_id)
24{
25 if (!mux->data.reg)
26 return -EINVAL;
27
28 /*
29 * Write to the register, followed by a read to ensure the write is
30 * completed on a "posted" bus, for example PCI or write buffers.
31 * The endianness of reading doesn't matter and the return data
32 * is not used.
33 */
34 switch (mux->data.reg_size) {
35 case 4:
36 if (mux->data.little_endian)
37 iowrite32(chan_id, mux->data.reg);
38 else
39 iowrite32be(chan_id, mux->data.reg);
40 if (!mux->data.write_only)
41 ioread32(mux->data.reg);
42 break;
43 case 2:
44 if (mux->data.little_endian)
45 iowrite16(chan_id, mux->data.reg);
46 else
47 iowrite16be(chan_id, mux->data.reg);
48 if (!mux->data.write_only)
49 ioread16(mux->data.reg);
50 break;
51 case 1:
52 iowrite8(chan_id, mux->data.reg);
53 if (!mux->data.write_only)
54 ioread8(mux->data.reg);
55 break;
56 }
57
58 return 0;
59}
60
61static int i2c_mux_reg_select(struct i2c_mux_core *muxc, u32 chan)
62{
63 struct regmux *mux = i2c_mux_priv(muxc);
64
65 return i2c_mux_reg_set(mux, chan);
66}
67
68static int i2c_mux_reg_deselect(struct i2c_mux_core *muxc, u32 chan)
69{
70 struct regmux *mux = i2c_mux_priv(muxc);
71
72 if (mux->data.idle_in_use)
73 return i2c_mux_reg_set(mux, mux->data.idle);
74
75 return 0;
76}
77
78#ifdef CONFIG_OF
79static int i2c_mux_reg_probe_dt(struct regmux *mux,
80 struct platform_device *pdev)
81{
82 struct device_node *np = pdev->dev.of_node;
83 struct device_node *adapter_np, *child;
84 struct i2c_adapter *adapter;
85 struct resource res;
86 unsigned *values;
87 int i = 0;
88
89 if (!np)
90 return -ENODEV;
91
92 adapter_np = of_parse_phandle(np, "i2c-parent", 0);
93 if (!adapter_np) {
94 dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
95 return -ENODEV;
96 }
97 adapter = of_find_i2c_adapter_by_node(adapter_np);
98 of_node_put(adapter_np);
99 if (!adapter)
100 return -EPROBE_DEFER;
101
102 mux->data.parent = i2c_adapter_id(adapter);
103 put_device(&adapter->dev);
104
105 mux->data.n_values = of_get_child_count(np);
106 if (of_property_read_bool(np, "little-endian")) {
107 mux->data.little_endian = true;
108 } else if (of_property_read_bool(np, "big-endian")) {
109 mux->data.little_endian = false;
110 } else {
111#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : \
112 defined(__LITTLE_ENDIAN)
113 mux->data.little_endian = true;
114#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : \
115 defined(__BIG_ENDIAN)
116 mux->data.little_endian = false;
117#else
118#error Endianness not defined?
119#endif
120 }
121 mux->data.write_only = of_property_read_bool(np, "write-only");
122
123 values = devm_kcalloc(&pdev->dev,
124 mux->data.n_values, sizeof(*mux->data.values),
125 GFP_KERNEL);
126 if (!values)
127 return -ENOMEM;
128
129 for_each_child_of_node(np, child) {
130 of_property_read_u32(child, "reg", values + i);
131 i++;
132 }
133 mux->data.values = values;
134
135 if (!of_property_read_u32(np, "idle-state", &mux->data.idle))
136 mux->data.idle_in_use = true;
137
138 /* map address from "reg" if exists */
139 if (of_address_to_resource(np, 0, &res) == 0) {
140 mux->data.reg_size = resource_size(&res);
141 mux->data.reg = devm_ioremap_resource(&pdev->dev, &res);
142 if (IS_ERR(mux->data.reg))
143 return PTR_ERR(mux->data.reg);
144 }
145
146 return 0;
147}
148#else
149static int i2c_mux_reg_probe_dt(struct regmux *mux,
150 struct platform_device *pdev)
151{
152 return 0;
153}
154#endif
155
156static int i2c_mux_reg_probe(struct platform_device *pdev)
157{
158 struct i2c_mux_core *muxc;
159 struct regmux *mux;
160 struct i2c_adapter *parent;
161 struct resource *res;
162 unsigned int class;
163 int i, ret, nr;
164
165 mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
166 if (!mux)
167 return -ENOMEM;
168
169 if (dev_get_platdata(&pdev->dev)) {
170 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
171 sizeof(mux->data));
172 } else {
173 ret = i2c_mux_reg_probe_dt(mux, pdev);
174 if (ret == -EPROBE_DEFER)
175 return ret;
176
177 if (ret < 0) {
178 dev_err(&pdev->dev, "Error parsing device tree");
179 return ret;
180 }
181 }
182
183 parent = i2c_get_adapter(mux->data.parent);
184 if (!parent)
185 return -EPROBE_DEFER;
186
187 if (!mux->data.reg) {
188 dev_info(&pdev->dev,
189 "Register not set, using platform resource\n");
190 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
191 mux->data.reg_size = resource_size(res);
192 mux->data.reg = devm_ioremap_resource(&pdev->dev, res);
193 if (IS_ERR(mux->data.reg)) {
194 ret = PTR_ERR(mux->data.reg);
195 goto err_put_parent;
196 }
197 }
198
199 if (mux->data.reg_size != 4 && mux->data.reg_size != 2 &&
200 mux->data.reg_size != 1) {
201 dev_err(&pdev->dev, "Invalid register size\n");
202 ret = -EINVAL;
203 goto err_put_parent;
204 }
205
206 muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values, 0, 0,
207 i2c_mux_reg_select, NULL);
208 if (!muxc) {
209 ret = -ENOMEM;
210 goto err_put_parent;
211 }
212 muxc->priv = mux;
213
214 platform_set_drvdata(pdev, muxc);
215
216 if (mux->data.idle_in_use)
217 muxc->deselect = i2c_mux_reg_deselect;
218
219 for (i = 0; i < mux->data.n_values; i++) {
220 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
221 class = mux->data.classes ? mux->data.classes[i] : 0;
222
223 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
224 if (ret)
225 goto err_del_mux_adapters;
226 }
227
228 dev_dbg(&pdev->dev, "%d port mux on %s adapter\n",
229 mux->data.n_values, muxc->parent->name);
230
231 return 0;
232
233err_del_mux_adapters:
234 i2c_mux_del_adapters(muxc);
235err_put_parent:
236 i2c_put_adapter(parent);
237
238 return ret;
239}
240
241static int i2c_mux_reg_remove(struct platform_device *pdev)
242{
243 struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
244
245 i2c_mux_del_adapters(muxc);
246 i2c_put_adapter(muxc->parent);
247
248 return 0;
249}
250
251static const struct of_device_id i2c_mux_reg_of_match[] = {
252 { .compatible = "i2c-mux-reg", },
253 {},
254};
255MODULE_DEVICE_TABLE(of, i2c_mux_reg_of_match);
256
257static struct platform_driver i2c_mux_reg_driver = {
258 .probe = i2c_mux_reg_probe,
259 .remove = i2c_mux_reg_remove,
260 .driver = {
261 .name = "i2c-mux-reg",
262 .of_match_table = of_match_ptr(i2c_mux_reg_of_match),
263 },
264};
265
266module_platform_driver(i2c_mux_reg_driver);
267
268MODULE_DESCRIPTION("Register-based I2C multiplexer driver");
269MODULE_AUTHOR("York Sun <yorksun@freescale.com>");
270MODULE_LICENSE("GPL");
271MODULE_ALIAS("platform:i2c-mux-reg");