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 | |
19 | struct regmux { |
20 | struct i2c_mux_reg_platform_data data; |
21 | }; |
22 | |
23 | static 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 | |
61 | static 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_id: chan); |
66 | } |
67 | |
68 | static 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, chan_id: mux->data.idle); |
74 | |
75 | return 0; |
76 | } |
77 | |
78 | #ifdef CONFIG_OF |
79 | static 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, phandle_name: "i2c-parent" , index: 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(node: adapter_np); |
98 | of_node_put(node: adapter_np); |
99 | if (!adapter) |
100 | return -EPROBE_DEFER; |
101 | |
102 | mux->data.parent = i2c_adapter_id(adap: adapter); |
103 | put_device(dev: &adapter->dev); |
104 | |
105 | mux->data.n_values = of_get_child_count(np); |
106 | if (of_property_read_bool(np, propname: "little-endian" )) { |
107 | mux->data.little_endian = true; |
108 | } else if (of_property_read_bool(np, propname: "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, propname: "write-only" ); |
122 | |
123 | values = devm_kcalloc(dev: &pdev->dev, |
124 | n: mux->data.n_values, size: 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(np: child, propname: "reg" , out_value: values + i); |
131 | i++; |
132 | } |
133 | mux->data.values = values; |
134 | |
135 | if (!of_property_read_u32(np, propname: "idle-state" , out_value: &mux->data.idle)) |
136 | mux->data.idle_in_use = true; |
137 | |
138 | /* map address from "reg" if exists */ |
139 | if (of_address_to_resource(dev: np, index: 0, r: &res) == 0) { |
140 | mux->data.reg_size = resource_size(res: &res); |
141 | mux->data.reg = devm_ioremap_resource(dev: &pdev->dev, res: &res); |
142 | if (IS_ERR(ptr: mux->data.reg)) |
143 | return PTR_ERR(ptr: mux->data.reg); |
144 | } |
145 | |
146 | return 0; |
147 | } |
148 | #else |
149 | static int i2c_mux_reg_probe_dt(struct regmux *mux, |
150 | struct platform_device *pdev) |
151 | { |
152 | return 0; |
153 | } |
154 | #endif |
155 | |
156 | static 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(dev: &pdev->dev, size: sizeof(*mux), GFP_KERNEL); |
166 | if (!mux) |
167 | return -ENOMEM; |
168 | |
169 | if (dev_get_platdata(dev: &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 < 0) |
175 | return dev_err_probe(dev: &pdev->dev, err: ret, |
176 | fmt: "Error parsing device tree" ); |
177 | } |
178 | |
179 | parent = i2c_get_adapter(nr: mux->data.parent); |
180 | if (!parent) |
181 | return -EPROBE_DEFER; |
182 | |
183 | if (!mux->data.reg) { |
184 | dev_info(&pdev->dev, |
185 | "Register not set, using platform resource\n" ); |
186 | mux->data.reg = devm_platform_get_and_ioremap_resource(pdev, index: 0, res: &res); |
187 | if (IS_ERR(ptr: mux->data.reg)) { |
188 | ret = PTR_ERR(ptr: mux->data.reg); |
189 | goto err_put_parent; |
190 | } |
191 | mux->data.reg_size = resource_size(res); |
192 | } |
193 | |
194 | if (mux->data.reg_size != 4 && mux->data.reg_size != 2 && |
195 | mux->data.reg_size != 1) { |
196 | dev_err(&pdev->dev, "Invalid register size\n" ); |
197 | ret = -EINVAL; |
198 | goto err_put_parent; |
199 | } |
200 | |
201 | muxc = i2c_mux_alloc(parent, dev: &pdev->dev, max_adapters: mux->data.n_values, sizeof_priv: 0, flags: 0, |
202 | select: i2c_mux_reg_select, NULL); |
203 | if (!muxc) { |
204 | ret = -ENOMEM; |
205 | goto err_put_parent; |
206 | } |
207 | muxc->priv = mux; |
208 | |
209 | platform_set_drvdata(pdev, data: muxc); |
210 | |
211 | if (mux->data.idle_in_use) |
212 | muxc->deselect = i2c_mux_reg_deselect; |
213 | |
214 | for (i = 0; i < mux->data.n_values; i++) { |
215 | nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0; |
216 | class = mux->data.classes ? mux->data.classes[i] : 0; |
217 | |
218 | ret = i2c_mux_add_adapter(muxc, force_nr: nr, chan_id: mux->data.values[i], class); |
219 | if (ret) |
220 | goto err_del_mux_adapters; |
221 | } |
222 | |
223 | dev_dbg(&pdev->dev, "%d port mux on %s adapter\n" , |
224 | mux->data.n_values, muxc->parent->name); |
225 | |
226 | return 0; |
227 | |
228 | err_del_mux_adapters: |
229 | i2c_mux_del_adapters(muxc); |
230 | err_put_parent: |
231 | i2c_put_adapter(adap: parent); |
232 | |
233 | return ret; |
234 | } |
235 | |
236 | static void i2c_mux_reg_remove(struct platform_device *pdev) |
237 | { |
238 | struct i2c_mux_core *muxc = platform_get_drvdata(pdev); |
239 | |
240 | i2c_mux_del_adapters(muxc); |
241 | i2c_put_adapter(adap: muxc->parent); |
242 | } |
243 | |
244 | static const struct of_device_id i2c_mux_reg_of_match[] = { |
245 | { .compatible = "i2c-mux-reg" , }, |
246 | {}, |
247 | }; |
248 | MODULE_DEVICE_TABLE(of, i2c_mux_reg_of_match); |
249 | |
250 | static struct platform_driver i2c_mux_reg_driver = { |
251 | .probe = i2c_mux_reg_probe, |
252 | .remove_new = i2c_mux_reg_remove, |
253 | .driver = { |
254 | .name = "i2c-mux-reg" , |
255 | .of_match_table = of_match_ptr(i2c_mux_reg_of_match), |
256 | }, |
257 | }; |
258 | |
259 | module_platform_driver(i2c_mux_reg_driver); |
260 | |
261 | MODULE_DESCRIPTION("Register-based I2C multiplexer driver" ); |
262 | MODULE_AUTHOR("York Sun <yorksun@freescale.com>" ); |
263 | MODULE_LICENSE("GPL" ); |
264 | MODULE_ALIAS("platform:i2c-mux-reg" ); |
265 | |