1 | // SPDX-License-Identifier: GPL-2.0+ |
2 | // |
3 | // Gateworks I2C PLD GPIO expander |
4 | // |
5 | // Copyright (C) 2019 Linus Walleij <linus.walleij@linaro.org> |
6 | // |
7 | // Based on code and know-how from the OpenWrt driver: |
8 | // Copyright (C) 2009 Gateworks Corporation |
9 | // Authors: Chris Lang, Imre Kaloz |
10 | |
11 | #include <linux/bits.h> |
12 | #include <linux/kernel.h> |
13 | #include <linux/slab.h> |
14 | #include <linux/gpio/driver.h> |
15 | #include <linux/i2c.h> |
16 | #include <linux/module.h> |
17 | |
18 | /** |
19 | * struct gw_pld - State container for Gateworks PLD |
20 | * @chip: GPIO chip instance |
21 | * @client: I2C client |
22 | * @out: shadow register for the output bute |
23 | */ |
24 | struct gw_pld { |
25 | struct gpio_chip chip; |
26 | struct i2c_client *client; |
27 | u8 out; |
28 | }; |
29 | |
30 | /* |
31 | * The Gateworks I2C PLD chip only expose one read and one write register. |
32 | * Writing a "one" bit (to match the reset state) lets that pin be used as an |
33 | * input. It is an open-drain model. |
34 | */ |
35 | static int gw_pld_input8(struct gpio_chip *gc, unsigned offset) |
36 | { |
37 | struct gw_pld *gw = gpiochip_get_data(gc); |
38 | |
39 | gw->out |= BIT(offset); |
40 | return i2c_smbus_write_byte(client: gw->client, value: gw->out); |
41 | } |
42 | |
43 | static int gw_pld_get8(struct gpio_chip *gc, unsigned offset) |
44 | { |
45 | struct gw_pld *gw = gpiochip_get_data(gc); |
46 | s32 val; |
47 | |
48 | val = i2c_smbus_read_byte(client: gw->client); |
49 | |
50 | return (val < 0) ? 0 : !!(val & BIT(offset)); |
51 | } |
52 | |
53 | static int gw_pld_output8(struct gpio_chip *gc, unsigned offset, int value) |
54 | { |
55 | struct gw_pld *gw = gpiochip_get_data(gc); |
56 | |
57 | if (value) |
58 | gw->out |= BIT(offset); |
59 | else |
60 | gw->out &= ~BIT(offset); |
61 | |
62 | return i2c_smbus_write_byte(client: gw->client, value: gw->out); |
63 | } |
64 | |
65 | static void gw_pld_set8(struct gpio_chip *gc, unsigned offset, int value) |
66 | { |
67 | gw_pld_output8(gc, offset, value); |
68 | } |
69 | |
70 | static int gw_pld_probe(struct i2c_client *client) |
71 | { |
72 | struct device *dev = &client->dev; |
73 | struct gw_pld *gw; |
74 | int ret; |
75 | |
76 | gw = devm_kzalloc(dev, size: sizeof(*gw), GFP_KERNEL); |
77 | if (!gw) |
78 | return -ENOMEM; |
79 | |
80 | gw->chip.base = -1; |
81 | gw->chip.can_sleep = true; |
82 | gw->chip.parent = dev; |
83 | gw->chip.owner = THIS_MODULE; |
84 | gw->chip.label = dev_name(dev); |
85 | gw->chip.ngpio = 8; |
86 | gw->chip.direction_input = gw_pld_input8; |
87 | gw->chip.get = gw_pld_get8; |
88 | gw->chip.direction_output = gw_pld_output8; |
89 | gw->chip.set = gw_pld_set8; |
90 | gw->client = client; |
91 | |
92 | /* |
93 | * The Gateworks I2C PLD chip does not properly send the acknowledge |
94 | * bit at all times, but we can still use the standard i2c_smbus |
95 | * functions by simply ignoring this bit. |
96 | */ |
97 | client->flags |= I2C_M_IGNORE_NAK; |
98 | gw->out = 0xFF; |
99 | |
100 | i2c_set_clientdata(client, data: gw); |
101 | |
102 | ret = devm_gpiochip_add_data(dev, &gw->chip, gw); |
103 | if (ret) |
104 | return ret; |
105 | |
106 | dev_info(dev, "registered Gateworks PLD GPIO device\n" ); |
107 | |
108 | return 0; |
109 | } |
110 | |
111 | static const struct i2c_device_id gw_pld_id[] = { |
112 | { "gw-pld" , }, |
113 | { } |
114 | }; |
115 | MODULE_DEVICE_TABLE(i2c, gw_pld_id); |
116 | |
117 | static const struct of_device_id gw_pld_dt_ids[] = { |
118 | { .compatible = "gateworks,pld-gpio" , }, |
119 | { }, |
120 | }; |
121 | MODULE_DEVICE_TABLE(of, gw_pld_dt_ids); |
122 | |
123 | static struct i2c_driver gw_pld_driver = { |
124 | .driver = { |
125 | .name = "gw_pld" , |
126 | .of_match_table = gw_pld_dt_ids, |
127 | }, |
128 | .probe = gw_pld_probe, |
129 | .id_table = gw_pld_id, |
130 | }; |
131 | module_i2c_driver(gw_pld_driver); |
132 | |
133 | MODULE_LICENSE("GPL" ); |
134 | MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>" ); |
135 | |