// SPDX-License-Identifier: GPL-2.0-only
/*
 * DRM driver for Solomon SSD13xx OLED displays (SPI bus)
 *
 * Copyright 2022 Red Hat Inc.
 * Authors: Javier Martinez Canillas <javierm@redhat.com>
 */
#include <linux/spi/spi.h>
#include <linux/module.h>

#include "ssd130x.h"

#define DRIVER_NAME     "ssd130x-spi"
#define DRIVER_DESC     "DRM driver for Solomon SSD13xx OLED displays (SPI)"

struct ssd130x_spi_transport {
        struct spi_device *spi;
        struct gpio_desc *dc;
};

/*
 * The regmap bus .write handler, it is just a wrapper around spi_write()
 * but toggling the Data/Command control pin (D/C#). Since for 4-wire SPI
 * a D/C# pin is used, in contrast with I2C where a control byte is sent,
 * prior to every data byte, that contains a bit with the D/C# value.
 *
 * These control bytes are considered registers by the ssd130x core driver
 * and can be used by the ssd130x SPI driver to determine if the data sent
 * is for a command register or for the Graphic Display Data RAM (GDDRAM).
 */
static int ssd130x_spi_write(void *context, const void *data, size_t count)
{
        struct ssd130x_spi_transport *t = context;
        struct spi_device *spi = t->spi;
        const u8 *reg = data;

        if (*reg == SSD13XX_COMMAND)
                gpiod_set_value_cansleep(t->dc, 0);

        if (*reg == SSD13XX_DATA)
                gpiod_set_value_cansleep(t->dc, 1);

        /* Remove control byte since is not used in a 4-wire SPI interface */
        return spi_write(spi, reg + 1, count - 1);
}

/* The ssd130x driver does not read registers but regmap expects a .read */
static int ssd130x_spi_read(void *context, const void *reg, size_t reg_size,
                            void *val, size_t val_size)
{
        return -EOPNOTSUPP;
}

static const struct regmap_config ssd130x_spi_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
        .write = ssd130x_spi_write,
        .read = ssd130x_spi_read,
        .can_multi_write = true,
};

static int ssd130x_spi_probe(struct spi_device *spi)
{
        struct ssd130x_spi_transport *t;
        struct ssd130x_device *ssd130x;
        struct regmap *regmap;
        struct gpio_desc *dc;
        struct device *dev = &spi->dev;

        dc = devm_gpiod_get(dev, "dc", GPIOD_OUT_LOW);
        if (IS_ERR(dc))
                return dev_err_probe(dev, PTR_ERR(dc),
                                     "Failed to get dc gpio\n");

        t = devm_kzalloc(dev, sizeof(*t), GFP_KERNEL);
        if (!t)
                return -ENOMEM;

        t->spi = spi;
        t->dc = dc;

        regmap = devm_regmap_init(dev, NULL, t, &ssd130x_spi_regmap_config);
        if (IS_ERR(regmap))
                return PTR_ERR(regmap);

        ssd130x = ssd130x_probe(dev, regmap);
        if (IS_ERR(ssd130x))
                return PTR_ERR(ssd130x);

        spi_set_drvdata(spi, ssd130x);

        return 0;
}

static void ssd130x_spi_remove(struct spi_device *spi)
{
        struct ssd130x_device *ssd130x = spi_get_drvdata(spi);

        ssd130x_remove(ssd130x);
}

static void ssd130x_spi_shutdown(struct spi_device *spi)
{
        struct ssd130x_device *ssd130x = spi_get_drvdata(spi);

        ssd130x_shutdown(ssd130x);
}

static const struct of_device_id ssd130x_of_match[] = {
        /* ssd130x family */
        {
                .compatible = "sinowealth,sh1106",
                .data = &ssd130x_variants[SH1106_ID],
        },
        {
                .compatible = "solomon,ssd1305",
                .data = &ssd130x_variants[SSD1305_ID],
        },
        {
                .compatible = "solomon,ssd1306",
                .data = &ssd130x_variants[SSD1306_ID],
        },
        {
                .compatible = "solomon,ssd1307",
                .data = &ssd130x_variants[SSD1307_ID],
        },
        {
                .compatible = "solomon,ssd1309",
                .data = &ssd130x_variants[SSD1309_ID],
        },
        /* ssd132x family */
        {
                .compatible = "solomon,ssd1322",
                .data = &ssd130x_variants[SSD1322_ID],
        },
        {
                .compatible = "solomon,ssd1325",
                .data = &ssd130x_variants[SSD1325_ID],
        },
        {
                .compatible = "solomon,ssd1327",
                .data = &ssd130x_variants[SSD1327_ID],
        },
        /* ssd133x family */
        {
                .compatible = "solomon,ssd1331",
                .data = &ssd130x_variants[SSD1331_ID],
        },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, ssd130x_of_match);

/*
 * The SPI core always reports a MODALIAS uevent of the form "spi:<dev>", even
 * if the device was registered via OF. This means that the module will not be
 * auto loaded, unless it contains an alias that matches the MODALIAS reported.
 *
 * To workaround this issue, add a SPI device ID table. Even when this should
 * not be needed for this driver to match the registered SPI devices.
 */
static const struct spi_device_id ssd130x_spi_id[] = {
        /* ssd130x family */
        { "sh1106",  SH1106_ID },
        { "ssd1305", SSD1305_ID },
        { "ssd1306", SSD1306_ID },
        { "ssd1307", SSD1307_ID },
        { "ssd1309", SSD1309_ID },
        /* ssd132x family */
        { "ssd1322", SSD1322_ID },
        { "ssd1325", SSD1325_ID },
        { "ssd1327", SSD1327_ID },
        /* ssd133x family */
        { "ssd1331", SSD1331_ID },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(spi, ssd130x_spi_id);

static struct spi_driver ssd130x_spi_driver = {
        .driver = {
                .name = DRIVER_NAME,
                .of_match_table = ssd130x_of_match,
        },
        .id_table = ssd130x_spi_id,
        .probe = ssd130x_spi_probe,
        .remove = ssd130x_spi_remove,
        .shutdown = ssd130x_spi_shutdown,
};
module_spi_driver(ssd130x_spi_driver);

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_AUTHOR("Javier Martinez Canillas <javierm@redhat.com>");
MODULE_LICENSE("GPL");
MODULE_IMPORT_NS("DRM_SSD130X");