Commit | Line | Data |
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92ed1a76 PK |
1 | /* |
2 | * I2C multiplexer using GPIO API | |
3 | * | |
4 | * Peter Korsgaard <peter.korsgaard@barco.com> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 as | |
8 | * published by the Free Software Foundation. | |
9 | */ | |
10 | ||
11 | #include <linux/i2c.h> | |
12 | #include <linux/i2c-mux.h> | |
13 | #include <linux/gpio-i2cmux.h> | |
14 | #include <linux/platform_device.h> | |
15 | #include <linux/init.h> | |
16 | #include <linux/module.h> | |
17 | #include <linux/slab.h> | |
18 | #include <linux/gpio.h> | |
19 | ||
20 | struct gpiomux { | |
21 | struct i2c_adapter *parent; | |
22 | struct i2c_adapter **adap; /* child busses */ | |
23 | struct gpio_i2cmux_platform_data data; | |
24 | }; | |
25 | ||
26 | static void gpiomux_set(const struct gpiomux *mux, unsigned val) | |
27 | { | |
28 | int i; | |
29 | ||
30 | for (i = 0; i < mux->data.n_gpios; i++) | |
31 | gpio_set_value(mux->data.gpios[i], val & (1 << i)); | |
32 | } | |
33 | ||
34 | static int gpiomux_select(struct i2c_adapter *adap, void *data, u32 chan) | |
35 | { | |
36 | struct gpiomux *mux = data; | |
37 | ||
38 | gpiomux_set(mux, mux->data.values[chan]); | |
39 | ||
40 | return 0; | |
41 | } | |
42 | ||
43 | static int gpiomux_deselect(struct i2c_adapter *adap, void *data, u32 chan) | |
44 | { | |
45 | struct gpiomux *mux = data; | |
46 | ||
47 | gpiomux_set(mux, mux->data.idle); | |
48 | ||
49 | return 0; | |
50 | } | |
51 | ||
52 | static int __devinit gpiomux_probe(struct platform_device *pdev) | |
53 | { | |
54 | struct gpiomux *mux; | |
55 | struct gpio_i2cmux_platform_data *pdata; | |
56 | struct i2c_adapter *parent; | |
57 | int (*deselect) (struct i2c_adapter *, void *, u32); | |
58 | unsigned initial_state; | |
59 | int i, ret; | |
60 | ||
61 | pdata = pdev->dev.platform_data; | |
62 | if (!pdata) { | |
63 | dev_err(&pdev->dev, "Missing platform data\n"); | |
64 | return -ENODEV; | |
65 | } | |
66 | ||
67 | parent = i2c_get_adapter(pdata->parent); | |
68 | if (!parent) { | |
69 | dev_err(&pdev->dev, "Parent adapter (%d) not found\n", | |
70 | pdata->parent); | |
71 | return -ENODEV; | |
72 | } | |
73 | ||
74 | mux = kzalloc(sizeof(*mux), GFP_KERNEL); | |
75 | if (!mux) { | |
76 | ret = -ENOMEM; | |
77 | goto alloc_failed; | |
78 | } | |
79 | ||
80 | mux->parent = parent; | |
81 | mux->data = *pdata; | |
82 | mux->adap = kzalloc(sizeof(struct i2c_adapter *) * pdata->n_values, | |
83 | GFP_KERNEL); | |
84 | if (!mux->adap) { | |
85 | ret = -ENOMEM; | |
86 | goto alloc_failed2; | |
87 | } | |
88 | ||
89 | if (pdata->idle != GPIO_I2CMUX_NO_IDLE) { | |
90 | initial_state = pdata->idle; | |
91 | deselect = gpiomux_deselect; | |
92 | } else { | |
93 | initial_state = pdata->values[0]; | |
94 | deselect = NULL; | |
95 | } | |
96 | ||
97 | for (i = 0; i < pdata->n_gpios; i++) { | |
98 | ret = gpio_request(pdata->gpios[i], "gpio-i2cmux"); | |
99 | if (ret) | |
100 | goto err_request_gpio; | |
101 | gpio_direction_output(pdata->gpios[i], | |
102 | initial_state & (1 << i)); | |
103 | } | |
104 | ||
105 | for (i = 0; i < pdata->n_values; i++) { | |
106 | u32 nr = pdata->base_nr ? (pdata->base_nr + i) : 0; | |
107 | ||
108 | mux->adap[i] = i2c_add_mux_adapter(parent, mux, nr, i, | |
109 | gpiomux_select, deselect); | |
110 | if (!mux->adap[i]) { | |
111 | ret = -ENODEV; | |
112 | dev_err(&pdev->dev, "Failed to add adapter %d\n", i); | |
113 | goto add_adapter_failed; | |
114 | } | |
115 | } | |
116 | ||
117 | dev_info(&pdev->dev, "%d port mux on %s adapter\n", | |
118 | pdata->n_values, parent->name); | |
119 | ||
120 | platform_set_drvdata(pdev, mux); | |
121 | ||
122 | return 0; | |
123 | ||
124 | add_adapter_failed: | |
125 | for (; i > 0; i--) | |
126 | i2c_del_mux_adapter(mux->adap[i - 1]); | |
127 | i = pdata->n_gpios; | |
128 | err_request_gpio: | |
129 | for (; i > 0; i--) | |
130 | gpio_free(pdata->gpios[i - 1]); | |
131 | kfree(mux->adap); | |
132 | alloc_failed2: | |
133 | kfree(mux); | |
134 | alloc_failed: | |
135 | i2c_put_adapter(parent); | |
136 | ||
137 | return ret; | |
138 | } | |
139 | ||
140 | static int __devexit gpiomux_remove(struct platform_device *pdev) | |
141 | { | |
142 | struct gpiomux *mux = platform_get_drvdata(pdev); | |
143 | int i; | |
144 | ||
145 | for (i = 0; i < mux->data.n_values; i++) | |
146 | i2c_del_mux_adapter(mux->adap[i]); | |
147 | ||
148 | for (i = 0; i < mux->data.n_gpios; i++) | |
149 | gpio_free(mux->data.gpios[i]); | |
150 | ||
151 | platform_set_drvdata(pdev, NULL); | |
152 | i2c_put_adapter(mux->parent); | |
153 | kfree(mux->adap); | |
154 | kfree(mux); | |
155 | ||
156 | return 0; | |
157 | } | |
158 | ||
159 | static struct platform_driver gpiomux_driver = { | |
160 | .probe = gpiomux_probe, | |
161 | .remove = __devexit_p(gpiomux_remove), | |
162 | .driver = { | |
163 | .owner = THIS_MODULE, | |
164 | .name = "gpio-i2cmux", | |
165 | }, | |
166 | }; | |
167 | ||
245e99cf | 168 | module_platform_driver(gpiomux_driver); |
92ed1a76 PK |
169 | |
170 | MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver"); | |
171 | MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>"); | |
172 | MODULE_LICENSE("GPL"); | |
173 | MODULE_ALIAS("platform:gpio-i2cmux"); |