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1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* | |
3 | * Copyright (C) 2015-2017 Pengutronix, Uwe Kleine-König <kernel@pengutronix.de> | |
4 | */ | |
5 | ||
6 | #include <linux/gpio/consumer.h> | |
7 | #include <linux/module.h> | |
ac316725 | 8 | #include <linux/mod_devicetable.h> |
fd639726 UKK |
9 | #include <linux/platform_device.h> |
10 | ||
11 | #include <linux/delay.h> | |
12 | ||
13 | #include "siox.h" | |
14 | ||
15 | #define DRIVER_NAME "siox-gpio" | |
16 | ||
17 | struct siox_gpio_ddata { | |
18 | struct gpio_desc *din; | |
19 | struct gpio_desc *dout; | |
20 | struct gpio_desc *dclk; | |
21 | struct gpio_desc *dld; | |
22 | }; | |
23 | ||
24 | static unsigned int siox_clkhigh_ns = 1000; | |
25 | static unsigned int siox_loadhigh_ns; | |
26 | static unsigned int siox_bytegap_ns; | |
27 | ||
28 | static int siox_gpio_pushpull(struct siox_master *smaster, | |
29 | size_t setbuf_len, const u8 setbuf[], | |
30 | size_t getbuf_len, u8 getbuf[]) | |
31 | { | |
32 | struct siox_gpio_ddata *ddata = siox_master_get_devdata(smaster); | |
33 | size_t i; | |
34 | size_t cycles = max(setbuf_len, getbuf_len); | |
35 | ||
36 | /* reset data and clock */ | |
37 | gpiod_set_value_cansleep(ddata->dout, 0); | |
38 | gpiod_set_value_cansleep(ddata->dclk, 0); | |
39 | ||
40 | gpiod_set_value_cansleep(ddata->dld, 1); | |
41 | ndelay(siox_loadhigh_ns); | |
42 | gpiod_set_value_cansleep(ddata->dld, 0); | |
43 | ||
44 | for (i = 0; i < cycles; ++i) { | |
45 | u8 set = 0, get = 0; | |
46 | size_t j; | |
47 | ||
48 | if (i >= cycles - setbuf_len) | |
49 | set = setbuf[i - (cycles - setbuf_len)]; | |
50 | ||
51 | for (j = 0; j < 8; ++j) { | |
52 | get <<= 1; | |
53 | if (gpiod_get_value_cansleep(ddata->din)) | |
54 | get |= 1; | |
55 | ||
56 | /* DOUT is logically inverted */ | |
57 | gpiod_set_value_cansleep(ddata->dout, !(set & 0x80)); | |
58 | set <<= 1; | |
59 | ||
60 | gpiod_set_value_cansleep(ddata->dclk, 1); | |
61 | ndelay(siox_clkhigh_ns); | |
62 | gpiod_set_value_cansleep(ddata->dclk, 0); | |
63 | } | |
64 | ||
65 | if (i < getbuf_len) | |
66 | getbuf[i] = get; | |
67 | ||
68 | ndelay(siox_bytegap_ns); | |
69 | } | |
70 | ||
71 | gpiod_set_value_cansleep(ddata->dld, 1); | |
72 | ndelay(siox_loadhigh_ns); | |
73 | gpiod_set_value_cansleep(ddata->dld, 0); | |
74 | ||
75 | /* | |
76 | * Resetting dout isn't necessary protocol wise, but it makes the | |
77 | * signals more pretty because the dout level is deterministic between | |
78 | * cycles. Note that this only affects dout between the master and the | |
79 | * first siox device. dout for the later devices depend on the output of | |
80 | * the previous siox device. | |
81 | */ | |
82 | gpiod_set_value_cansleep(ddata->dout, 0); | |
83 | ||
84 | return 0; | |
85 | } | |
86 | ||
87 | static int siox_gpio_probe(struct platform_device *pdev) | |
88 | { | |
89 | struct device *dev = &pdev->dev; | |
90 | struct siox_gpio_ddata *ddata; | |
91 | int ret; | |
92 | struct siox_master *smaster; | |
93 | ||
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94 | smaster = devm_siox_master_alloc(dev, sizeof(*ddata)); |
95 | if (!smaster) | |
96 | return dev_err_probe(dev, -ENOMEM, | |
97 | "failed to allocate siox master\n"); | |
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98 | |
99 | platform_set_drvdata(pdev, smaster); | |
100 | ddata = siox_master_get_devdata(smaster); | |
101 | ||
102 | ddata->din = devm_gpiod_get(dev, "din", GPIOD_IN); | |
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103 | if (IS_ERR(ddata->din)) |
104 | return dev_err_probe(dev, PTR_ERR(ddata->din), | |
105 | "Failed to get din GPIO\n"); | |
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106 | |
107 | ddata->dout = devm_gpiod_get(dev, "dout", GPIOD_OUT_LOW); | |
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108 | if (IS_ERR(ddata->dout)) |
109 | return dev_err_probe(dev, PTR_ERR(ddata->dout), | |
110 | "Failed to get dout GPIO\n"); | |
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111 | |
112 | ddata->dclk = devm_gpiod_get(dev, "dclk", GPIOD_OUT_LOW); | |
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113 | if (IS_ERR(ddata->dclk)) |
114 | return dev_err_probe(dev, PTR_ERR(ddata->dclk), | |
115 | "Failed to get dclk GPIO\n"); | |
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116 | |
117 | ddata->dld = devm_gpiod_get(dev, "dld", GPIOD_OUT_LOW); | |
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118 | if (IS_ERR(ddata->dld)) |
119 | return dev_err_probe(dev, PTR_ERR(ddata->dld), | |
120 | "Failed to get dld GPIO\n"); | |
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121 | |
122 | smaster->pushpull = siox_gpio_pushpull; | |
123 | /* XXX: determine automatically like spi does */ | |
124 | smaster->busno = 0; | |
125 | ||
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126 | ret = devm_siox_master_register(dev, smaster); |
127 | if (ret) | |
128 | return dev_err_probe(dev, ret, | |
129 | "Failed to register siox master\n"); | |
2c12932b | 130 | |
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131 | return 0; |
132 | } | |
133 | ||
134 | static const struct of_device_id siox_gpio_dt_ids[] = { | |
135 | { .compatible = "eckelmann,siox-gpio", }, | |
136 | { /* sentinel */ } | |
137 | }; | |
138 | MODULE_DEVICE_TABLE(of, siox_gpio_dt_ids); | |
139 | ||
140 | static struct platform_driver siox_gpio_driver = { | |
141 | .probe = siox_gpio_probe, | |
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142 | |
143 | .driver = { | |
144 | .name = DRIVER_NAME, | |
145 | .of_match_table = siox_gpio_dt_ids, | |
146 | }, | |
147 | }; | |
148 | module_platform_driver(siox_gpio_driver); | |
149 | ||
150 | MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>"); | |
151 | MODULE_LICENSE("GPL v2"); | |
152 | MODULE_ALIAS("platform:" DRIVER_NAME); |