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> |
8 | #include <linux/mod_devicetable.h> |
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(desc: ddata->dout, value: 0); |
38 | gpiod_set_value_cansleep(desc: ddata->dclk, value: 0); |
39 | |
40 | gpiod_set_value_cansleep(desc: ddata->dld, value: 1); |
41 | ndelay(siox_loadhigh_ns); |
42 | gpiod_set_value_cansleep(desc: ddata->dld, value: 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(desc: ddata->din)) |
54 | get |= 1; |
55 | |
56 | /* DOUT is logically inverted */ |
57 | gpiod_set_value_cansleep(desc: ddata->dout, value: !(set & 0x80)); |
58 | set <<= 1; |
59 | |
60 | gpiod_set_value_cansleep(desc: ddata->dclk, value: 1); |
61 | ndelay(siox_clkhigh_ns); |
62 | gpiod_set_value_cansleep(desc: ddata->dclk, value: 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(desc: ddata->dld, value: 1); |
72 | ndelay(siox_loadhigh_ns); |
73 | gpiod_set_value_cansleep(desc: ddata->dld, value: 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(desc: ddata->dout, value: 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 | |
94 | smaster = siox_master_alloc(dev: &pdev->dev, size: sizeof(*ddata)); |
95 | if (!smaster) { |
96 | dev_err(dev, "failed to allocate siox master\n" ); |
97 | return -ENOMEM; |
98 | } |
99 | |
100 | platform_set_drvdata(pdev, data: smaster); |
101 | ddata = siox_master_get_devdata(smaster); |
102 | |
103 | ddata->din = devm_gpiod_get(dev, con_id: "din" , flags: GPIOD_IN); |
104 | if (IS_ERR(ptr: ddata->din)) { |
105 | ret = dev_err_probe(dev, err: PTR_ERR(ptr: ddata->din), |
106 | fmt: "Failed to get din GPIO\n" ); |
107 | goto err; |
108 | } |
109 | |
110 | ddata->dout = devm_gpiod_get(dev, con_id: "dout" , flags: GPIOD_OUT_LOW); |
111 | if (IS_ERR(ptr: ddata->dout)) { |
112 | ret = dev_err_probe(dev, err: PTR_ERR(ptr: ddata->dout), |
113 | fmt: "Failed to get dout GPIO\n" ); |
114 | goto err; |
115 | } |
116 | |
117 | ddata->dclk = devm_gpiod_get(dev, con_id: "dclk" , flags: GPIOD_OUT_LOW); |
118 | if (IS_ERR(ptr: ddata->dclk)) { |
119 | ret = dev_err_probe(dev, err: PTR_ERR(ptr: ddata->dclk), |
120 | fmt: "Failed to get dclk GPIO\n" ); |
121 | goto err; |
122 | } |
123 | |
124 | ddata->dld = devm_gpiod_get(dev, con_id: "dld" , flags: GPIOD_OUT_LOW); |
125 | if (IS_ERR(ptr: ddata->dld)) { |
126 | ret = dev_err_probe(dev, err: PTR_ERR(ptr: ddata->dld), |
127 | fmt: "Failed to get dld GPIO\n" ); |
128 | goto err; |
129 | } |
130 | |
131 | smaster->pushpull = siox_gpio_pushpull; |
132 | /* XXX: determine automatically like spi does */ |
133 | smaster->busno = 0; |
134 | |
135 | ret = siox_master_register(smaster); |
136 | if (ret) { |
137 | dev_err_probe(dev, err: ret, |
138 | fmt: "Failed to register siox master\n" ); |
139 | err: |
140 | siox_master_put(smaster); |
141 | } |
142 | |
143 | return ret; |
144 | } |
145 | |
146 | static int siox_gpio_remove(struct platform_device *pdev) |
147 | { |
148 | struct siox_master *master = platform_get_drvdata(pdev); |
149 | |
150 | siox_master_unregister(smaster: master); |
151 | |
152 | return 0; |
153 | } |
154 | |
155 | static const struct of_device_id siox_gpio_dt_ids[] = { |
156 | { .compatible = "eckelmann,siox-gpio" , }, |
157 | { /* sentinel */ } |
158 | }; |
159 | MODULE_DEVICE_TABLE(of, siox_gpio_dt_ids); |
160 | |
161 | static struct platform_driver siox_gpio_driver = { |
162 | .probe = siox_gpio_probe, |
163 | .remove = siox_gpio_remove, |
164 | |
165 | .driver = { |
166 | .name = DRIVER_NAME, |
167 | .of_match_table = siox_gpio_dt_ids, |
168 | }, |
169 | }; |
170 | module_platform_driver(siox_gpio_driver); |
171 | |
172 | MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>" ); |
173 | MODULE_LICENSE("GPL v2" ); |
174 | MODULE_ALIAS("platform:" DRIVER_NAME); |
175 | |