ssd130x-spi.c

  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 -ENOMEM;
 78
 79	t->spi = spi;
 80	t->dc = dc;
 81
 82	regmap = devm_regmap_init(dev, NULL, t, &ssd130x_spi_regmap_config);
 83	if (IS_ERR(regmap))
 84		return PTR_ERR(regmap);
 85
 86	ssd130x = ssd130x_probe(dev, regmap);
 87	if (IS_ERR(ssd130x))
 88		return PTR_ERR(ssd130x);
 89
 90	spi_set_drvdata(spi, ssd130x);
 91
 92	return 0;
 93}
 94
 95static void ssd130x_spi_remove(struct spi_device *spi)
 96{
 97	struct ssd130x_device *ssd130x = spi_get_drvdata(spi);
 98
 99	ssd130x_remove(ssd130x);
100}
101
102static void ssd130x_spi_shutdown(struct spi_device *spi)
103{
104	struct ssd130x_device *ssd130x = spi_get_drvdata(spi);
105
106	ssd130x_shutdown(ssd130x);
107}
108
109static const struct of_device_id ssd130x_of_match[] = {
110	/* ssd130x family */
111	{
112		.compatible = "sinowealth,sh1106",
113		.data = &ssd130x_variants[SH1106_ID],
114	},
115	{
116		.compatible = "solomon,ssd1305",
117		.data = &ssd130x_variants[SSD1305_ID],
118	},
119	{
120		.compatible = "solomon,ssd1306",
121		.data = &ssd130x_variants[SSD1306_ID],
122	},
123	{
124		.compatible = "solomon,ssd1307",
125		.data = &ssd130x_variants[SSD1307_ID],
126	},
127	{
128		.compatible = "solomon,ssd1309",
129		.data = &ssd130x_variants[SSD1309_ID],
130	},
131	/* ssd132x family */
132	{
133		.compatible = "solomon,ssd1322",
134		.data = &ssd130x_variants[SSD1322_ID],
135	},
136	{
137		.compatible = "solomon,ssd1325",
138		.data = &ssd130x_variants[SSD1325_ID],
139	},
140	{
141		.compatible = "solomon,ssd1327",
142		.data = &ssd130x_variants[SSD1327_ID],
143	},
144	/* ssd133x family */
145	{
146		.compatible = "solomon,ssd1331",
147		.data = &ssd130x_variants[SSD1331_ID],
148	},
149	{ /* sentinel */ }
150};
151MODULE_DEVICE_TABLE(of, ssd130x_of_match);
152
153/*
154 * The SPI core always reports a MODALIAS uevent of the form "spi:<dev>", even
155 * if the device was registered via OF. This means that the module will not be
156 * auto loaded, unless it contains an alias that matches the MODALIAS reported.
157 *
158 * To workaround this issue, add a SPI device ID table. Even when this should
159 * not be needed for this driver to match the registered SPI devices.
160 */
161static const struct spi_device_id ssd130x_spi_id[] = {
162	/* ssd130x family */
163	{ "sh1106",  SH1106_ID },
164	{ "ssd1305", SSD1305_ID },
165	{ "ssd1306", SSD1306_ID },
166	{ "ssd1307", SSD1307_ID },
167	{ "ssd1309", SSD1309_ID },
168	/* ssd132x family */
169	{ "ssd1322", SSD1322_ID },
170	{ "ssd1325", SSD1325_ID },
171	{ "ssd1327", SSD1327_ID },
172	/* ssd133x family */
173	{ "ssd1331", SSD1331_ID },
174	{ /* sentinel */ }
175};
176MODULE_DEVICE_TABLE(spi, ssd130x_spi_id);
177
178static struct spi_driver ssd130x_spi_driver = {
179	.driver = {
180		.name = DRIVER_NAME,
181		.of_match_table = ssd130x_of_match,
182	},
183	.id_table = ssd130x_spi_id,
184	.probe = ssd130x_spi_probe,
185	.remove = ssd130x_spi_remove,
186	.shutdown = ssd130x_spi_shutdown,
187};
188module_spi_driver(ssd130x_spi_driver);
189
190MODULE_DESCRIPTION(DRIVER_DESC);
191MODULE_AUTHOR("Javier Martinez Canillas <javierm@redhat.com>");
192MODULE_LICENSE("GPL");
193MODULE_IMPORT_NS("DRM_SSD130X");