1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * DRM driver for Solomon SSD13xx OLED displays (SPI bus)
4 *
5 * Copyright 2022 Red Hat Inc.
6 * Authors: Javier Martinez Canillas <javierm@redhat.com>
7 */
8#include <linux/spi/spi.h>
9#include <linux/module.h>
10
11#include "ssd130x.h"
12
13#define DRIVER_NAME	"ssd130x-spi"
14#define DRIVER_DESC	"DRM driver for Solomon SSD13xx OLED displays (SPI)"
15
16struct ssd130x_spi_transport {
17	struct spi_device *spi;
18	struct gpio_desc *dc;
19};
20
21/*
22 * The regmap bus .write handler, it is just a wrapper around spi_write()
23 * but toggling the Data/Command control pin (D/C#). Since for 4-wire SPI
24 * a D/C# pin is used, in contrast with I2C where a control byte is sent,
25 * prior to every data byte, that contains a bit with the D/C# value.
26 *
27 * These control bytes are considered registers by the ssd130x core driver
28 * and can be used by the ssd130x SPI driver to determine if the data sent
29 * is for a command register or for the Graphic Display Data RAM (GDDRAM).
30 */
31static int ssd130x_spi_write(void *context, const void *data, size_t count)
32{
33	struct ssd130x_spi_transport *t = context;
34	struct spi_device *spi = t->spi;
35	const u8 *reg = data;
36
37	if (*reg == SSD13XX_COMMAND)
38		gpiod_set_value_cansleep(t->dc, 0);
39
40	if (*reg == SSD13XX_DATA)
41		gpiod_set_value_cansleep(t->dc, 1);
42
43	/* Remove control byte since is not used in a 4-wire SPI interface */
44	return spi_write(spi, reg + 1, count - 1);
45}
46
47/* The ssd130x driver does not read registers but regmap expects a .read */
48static int ssd130x_spi_read(void *context, const void *reg, size_t reg_size,
49			    void *val, size_t val_size)
50{
51	return -EOPNOTSUPP;
52}
53
54static const struct regmap_config ssd130x_spi_regmap_config = {
55	.reg_bits = 8,
56	.val_bits = 8,
57	.write = ssd130x_spi_write,
58	.read = ssd130x_spi_read,
59	.can_multi_write = true,
60};
61
62static int ssd130x_spi_probe(struct spi_device *spi)
63{
64	struct ssd130x_spi_transport *t;
65	struct ssd130x_device *ssd130x;
66	struct regmap *regmap;
67	struct gpio_desc *dc;
68	struct device *dev = &spi->dev;
69
70	dc = devm_gpiod_get(dev, "dc", GPIOD_OUT_LOW);
71	if (IS_ERR(dc))
72		return dev_err_probe(dev, PTR_ERR(dc),
73				     "Failed to get dc gpio\n");
74
75	t = devm_kzalloc(dev, sizeof(*t), GFP_KERNEL);
76	if (!t)
77		return dev_err_probe(dev, -ENOMEM,
78				     "Failed to allocate SPI transport data\n");
79
80	t->spi = spi;
81	t->dc = dc;
82
83	regmap = devm_regmap_init(dev, NULL, t, &ssd130x_spi_regmap_config);
84	if (IS_ERR(regmap))
85		return PTR_ERR(regmap);
86
87	ssd130x = ssd130x_probe(dev, regmap);
88	if (IS_ERR(ssd130x))
89		return PTR_ERR(ssd130x);
90
91	spi_set_drvdata(spi, ssd130x);
92
93	return 0;
94}
95
96static void ssd130x_spi_remove(struct spi_device *spi)
97{
98	struct ssd130x_device *ssd130x = spi_get_drvdata(spi);
99
100	ssd130x_remove(ssd130x);
101}
102
103static void ssd130x_spi_shutdown(struct spi_device *spi)
104{
105	struct ssd130x_device *ssd130x = spi_get_drvdata(spi);
106
107	ssd130x_shutdown(ssd130x);
108}
109
110static const struct of_device_id ssd130x_of_match[] = {
111	/* ssd130x family */
112	{
113		.compatible = "sinowealth,sh1106",
114		.data = &ssd130x_variants[SH1106_ID],
115	},
116	{
117		.compatible = "solomon,ssd1305",
118		.data = &ssd130x_variants[SSD1305_ID],
119	},
120	{
121		.compatible = "solomon,ssd1306",
122		.data = &ssd130x_variants[SSD1306_ID],
123	},
124	{
125		.compatible = "solomon,ssd1307",
126		.data = &ssd130x_variants[SSD1307_ID],
127	},
128	{
129		.compatible = "solomon,ssd1309",
130		.data = &ssd130x_variants[SSD1309_ID],
131	},
132	/* ssd132x family */
133	{
134		.compatible = "solomon,ssd1322",
135		.data = &ssd130x_variants[SSD1322_ID],
136	},
137	{
138		.compatible = "solomon,ssd1325",
139		.data = &ssd130x_variants[SSD1325_ID],
140	},
141	{
142		.compatible = "solomon,ssd1327",
143		.data = &ssd130x_variants[SSD1327_ID],
144	},
145	/* ssd133x family */
146	{
147		.compatible = "solomon,ssd1331",
148		.data = &ssd130x_variants[SSD1331_ID],
149	},
150	{ /* sentinel */ }
151};
152MODULE_DEVICE_TABLE(of, ssd130x_of_match);
153
154#if IS_MODULE(CONFIG_DRM_SSD130X_SPI)
155/*
156 * The SPI core always reports a MODALIAS uevent of the form "spi:<dev>", even
157 * if the device was registered via OF. This means that the module will not be
158 * auto loaded, unless it contains an alias that matches the MODALIAS reported.
159 *
160 * To workaround this issue, add a SPI device ID table. Even when this should
161 * not be needed for this driver to match the registered SPI devices.
162 */
163static const struct spi_device_id ssd130x_spi_table[] = {
164	/* ssd130x family */
165	{ "sh1106",  SH1106_ID },
166	{ "ssd1305", SSD1305_ID },
167	{ "ssd1306", SSD1306_ID },
168	{ "ssd1307", SSD1307_ID },
169	{ "ssd1309", SSD1309_ID },
170	/* ssd132x family */
171	{ "ssd1322", SSD1322_ID },
172	{ "ssd1325", SSD1325_ID },
173	{ "ssd1327", SSD1327_ID },
174	/* ssd133x family */
175	{ "ssd1331", SSD1331_ID },
176	{ /* sentinel */ }
177};
178MODULE_DEVICE_TABLE(spi, ssd130x_spi_table);
179#endif
180
181static struct spi_driver ssd130x_spi_driver = {
182	.driver = {
183		.name = DRIVER_NAME,
184		.of_match_table = ssd130x_of_match,
185	},
186	.probe = ssd130x_spi_probe,
187	.remove = ssd130x_spi_remove,
188	.shutdown = ssd130x_spi_shutdown,
189};
190module_spi_driver(ssd130x_spi_driver);
191
192MODULE_DESCRIPTION(DRIVER_DESC);
193MODULE_AUTHOR("Javier Martinez Canillas <javierm@redhat.com>");
194MODULE_LICENSE("GPL");
195MODULE_IMPORT_NS(DRM_SSD130X);
196