// SPDX-License-Identifier: GPL-2.0
/*
 * Digital I/O driver for Technologic Systems TS-5500
 *
 * Copyright (c) 2012 Savoir-faire Linux Inc.
 *      Vivien Didelot <vivien.didelot@savoirfairelinux.com>
 *
 * Technologic Systems platforms have pin blocks, exposing several Digital
 * Input/Output lines (DIO). This driver aims to support single pin blocks.
 * In that sense, the support is not limited to the TS-5500 blocks.
 * Actually, the following platforms have DIO support:
 *
 * TS-5500:
 *   Documentation: https://docs.embeddedts.com/TS-5500
 *   Blocks: DIO1, DIO2 and LCD port.
 *
 * TS-5600:
 *   Documentation: https://docs.embeddedts.com/TS-5600
 *   Blocks: LCD port (identical to TS-5500 LCD).
 */

#include <linux/bitops.h>
#include <linux/gpio/driver.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

/* List of supported Technologic Systems platforms DIO blocks */
enum ts5500_blocks { TS5500_DIO1, TS5500_DIO2, TS5500_LCD, TS5600_LCD };

struct ts5500_priv {
        const struct ts5500_dio *pinout;
        struct gpio_chip gpio_chip;
        spinlock_t lock;
        bool strap;
        u8 hwirq;
};

/*
 * Hex 7D is used to control several blocks (e.g. DIO2 and LCD port).
 * This flag ensures that the region has been requested by this driver.
 */
static bool hex7d_reserved;

/*
 * This structure is used to describe capabilities of DIO lines,
 * such as available directions and connected interrupt (if any).
 */
struct ts5500_dio {
        const u8 value_addr;
        const u8 value_mask;
        const u8 control_addr;
        const u8 control_mask;
        const bool no_input;
        const bool no_output;
        const u8 irq;
};

#define TS5500_DIO_IN_OUT(vaddr, vbit, caddr, cbit)     \
        {                                               \
                .value_addr = vaddr,                    \
                .value_mask = BIT(vbit),                \
                .control_addr = caddr,                  \
                .control_mask = BIT(cbit),              \
        }

#define TS5500_DIO_IN(addr, bit)                \
        {                                       \
                .value_addr = addr,             \
                .value_mask = BIT(bit),         \
                .no_output = true,              \
        }

#define TS5500_DIO_IN_IRQ(addr, bit, _irq)      \
        {                                       \
                .value_addr = addr,             \
                .value_mask = BIT(bit),         \
                .no_output = true,              \
                .irq = _irq,                    \
        }

#define TS5500_DIO_OUT(addr, bit)               \
        {                                       \
                .value_addr = addr,             \
                .value_mask = BIT(bit),         \
                .no_input = true,               \
        }

/*
 * Input/Output DIO lines are programmed in groups of 4. Their values are
 * available through 4 consecutive bits in a value port, whereas the direction
 * of these 4 lines is driven by only 1 bit in a control port.
 */
#define TS5500_DIO_GROUP(vaddr, vbitfrom, caddr, cbit)          \
        TS5500_DIO_IN_OUT(vaddr, vbitfrom + 0, caddr, cbit),    \
        TS5500_DIO_IN_OUT(vaddr, vbitfrom + 1, caddr, cbit),    \
        TS5500_DIO_IN_OUT(vaddr, vbitfrom + 2, caddr, cbit),    \
        TS5500_DIO_IN_OUT(vaddr, vbitfrom + 3, caddr, cbit)

/*
 * TS-5500 DIO1 block
 *
 *  value    control  dir    hw
 *  addr bit addr bit in out irq name     pin offset
 *
 *  0x7b  0  0x7a  0  x   x      DIO1_0   1   0
 *  0x7b  1  0x7a  0  x   x      DIO1_1   3   1
 *  0x7b  2  0x7a  0  x   x      DIO1_2   5   2
 *  0x7b  3  0x7a  0  x   x      DIO1_3   7   3
 *  0x7b  4  0x7a  1  x   x      DIO1_4   9   4
 *  0x7b  5  0x7a  1  x   x      DIO1_5   11  5
 *  0x7b  6  0x7a  1  x   x      DIO1_6   13  6
 *  0x7b  7  0x7a  1  x   x      DIO1_7   15  7
 *  0x7c  0  0x7a  5  x   x      DIO1_8   4   8
 *  0x7c  1  0x7a  5  x   x      DIO1_9   6   9
 *  0x7c  2  0x7a  5  x   x      DIO1_10  8   10
 *  0x7c  3  0x7a  5  x   x      DIO1_11  10  11
 *  0x7c  4           x          DIO1_12  12  12
 *  0x7c  5           x      7   DIO1_13  14  13
 */
static const struct ts5500_dio ts5500_dio1[] = {
        TS5500_DIO_GROUP(0x7b, 0, 0x7a, 0),
        TS5500_DIO_GROUP(0x7b, 4, 0x7a, 1),
        TS5500_DIO_GROUP(0x7c, 0, 0x7a, 5),
        TS5500_DIO_IN(0x7c, 4),
        TS5500_DIO_IN_IRQ(0x7c, 5, 7),
};

/*
 * TS-5500 DIO2 block
 *
 *  value    control  dir    hw
 *  addr bit addr bit in out irq name     pin offset
 *
 *  0x7e  0  0x7d  0  x   x      DIO2_0   1   0
 *  0x7e  1  0x7d  0  x   x      DIO2_1   3   1
 *  0x7e  2  0x7d  0  x   x      DIO2_2   5   2
 *  0x7e  3  0x7d  0  x   x      DIO2_3   7   3
 *  0x7e  4  0x7d  1  x   x      DIO2_4   9   4
 *  0x7e  5  0x7d  1  x   x      DIO2_5   11  5
 *  0x7e  6  0x7d  1  x   x      DIO2_6   13  6
 *  0x7e  7  0x7d  1  x   x      DIO2_7   15  7
 *  0x7f  0  0x7d  5  x   x      DIO2_8   4   8
 *  0x7f  1  0x7d  5  x   x      DIO2_9   6   9
 *  0x7f  2  0x7d  5  x   x      DIO2_10  8   10
 *  0x7f  3  0x7d  5  x   x      DIO2_11  10  11
 *  0x7f  4           x      6   DIO2_13  14  12
 */
static const struct ts5500_dio ts5500_dio2[] = {
        TS5500_DIO_GROUP(0x7e, 0, 0x7d, 0),
        TS5500_DIO_GROUP(0x7e, 4, 0x7d, 1),
        TS5500_DIO_GROUP(0x7f, 0, 0x7d, 5),
        TS5500_DIO_IN_IRQ(0x7f, 4, 6),
};

/*
 * TS-5500 LCD port used as DIO block
 * TS-5600 LCD port is identical
 *
 *  value    control  dir    hw
 *  addr bit addr bit in out irq name    pin offset
 *
 *  0x72  0  0x7d  2  x   x      LCD_0   8   0
 *  0x72  1  0x7d  2  x   x      LCD_1   7   1
 *  0x72  2  0x7d  2  x   x      LCD_2   10  2
 *  0x72  3  0x7d  2  x   x      LCD_3   9   3
 *  0x72  4  0x7d  3  x   x      LCD_4   12  4
 *  0x72  5  0x7d  3  x   x      LCD_5   11  5
 *  0x72  6  0x7d  3  x   x      LCD_6   14  6
 *  0x72  7  0x7d  3  x   x      LCD_7   13  7
 *  0x73  0               x      LCD_EN  5   8
 *  0x73  6           x          LCD_WR  6   9
 *  0x73  7           x      1   LCD_RS  3   10
 */
static const struct ts5500_dio ts5500_lcd[] = {
        TS5500_DIO_GROUP(0x72, 0, 0x7d, 2),
        TS5500_DIO_GROUP(0x72, 4, 0x7d, 3),
        TS5500_DIO_OUT(0x73, 0),
        TS5500_DIO_IN(0x73, 6),
        TS5500_DIO_IN_IRQ(0x73, 7, 1),
};

static inline void ts5500_set_mask(u8 mask, u8 addr)
{
        u8 val = inb(addr);
        val |= mask;
        outb(val, addr);
}

static inline void ts5500_clear_mask(u8 mask, u8 addr)
{
        u8 val = inb(addr);
        val &= ~mask;
        outb(val, addr);
}

static int ts5500_gpio_input(struct gpio_chip *chip, unsigned offset)
{
        struct ts5500_priv *priv = gpiochip_get_data(chip);
        const struct ts5500_dio line = priv->pinout[offset];
        unsigned long flags;

        if (line.no_input)
                return -ENXIO;

        if (line.no_output)
                return 0;

        spin_lock_irqsave(&priv->lock, flags);
        ts5500_clear_mask(line.control_mask, line.control_addr);
        spin_unlock_irqrestore(&priv->lock, flags);

        return 0;
}

static int ts5500_gpio_get(struct gpio_chip *chip, unsigned offset)
{
        struct ts5500_priv *priv = gpiochip_get_data(chip);
        const struct ts5500_dio line = priv->pinout[offset];

        return !!(inb(line.value_addr) & line.value_mask);
}

static int ts5500_gpio_output(struct gpio_chip *chip, unsigned offset, int val)
{
        struct ts5500_priv *priv = gpiochip_get_data(chip);
        const struct ts5500_dio line = priv->pinout[offset];
        unsigned long flags;

        if (line.no_output)
                return -ENXIO;

        spin_lock_irqsave(&priv->lock, flags);
        if (!line.no_input)
                ts5500_set_mask(line.control_mask, line.control_addr);

        if (val)
                ts5500_set_mask(line.value_mask, line.value_addr);
        else
                ts5500_clear_mask(line.value_mask, line.value_addr);
        spin_unlock_irqrestore(&priv->lock, flags);

        return 0;
}

static int ts5500_gpio_set(struct gpio_chip *chip, unsigned offset, int val)
{
        struct ts5500_priv *priv = gpiochip_get_data(chip);
        const struct ts5500_dio line = priv->pinout[offset];
        unsigned long flags;

        spin_lock_irqsave(&priv->lock, flags);
        if (val)
                ts5500_set_mask(line.value_mask, line.value_addr);
        else
                ts5500_clear_mask(line.value_mask, line.value_addr);
        spin_unlock_irqrestore(&priv->lock, flags);

        return 0;
}

static int ts5500_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
{
        struct ts5500_priv *priv = gpiochip_get_data(chip);
        const struct ts5500_dio *block = priv->pinout;
        const struct ts5500_dio line = block[offset];

        /* Only one pin is connected to an interrupt */
        if (line.irq)
                return line.irq;

        /* As this pin is input-only, we may strap it to another in/out pin */
        if (priv->strap)
                return priv->hwirq;

        return -ENXIO;
}

static int ts5500_enable_irq(struct ts5500_priv *priv)
{
        int ret = 0;
        unsigned long flags;

        spin_lock_irqsave(&priv->lock, flags);
        if (priv->hwirq == 7)
                ts5500_set_mask(BIT(7), 0x7a); /* DIO1_13 on IRQ7 */
        else if (priv->hwirq == 6)
                ts5500_set_mask(BIT(7), 0x7d); /* DIO2_13 on IRQ6 */
        else if (priv->hwirq == 1)
                ts5500_set_mask(BIT(6), 0x7d); /* LCD_RS on IRQ1 */
        else
                ret = -EINVAL;
        spin_unlock_irqrestore(&priv->lock, flags);

        return ret;
}

static void ts5500_disable_irq(struct ts5500_priv *priv)
{
        unsigned long flags;

        spin_lock_irqsave(&priv->lock, flags);
        if (priv->hwirq == 7)
                ts5500_clear_mask(BIT(7), 0x7a); /* DIO1_13 on IRQ7 */
        else if (priv->hwirq == 6)
                ts5500_clear_mask(BIT(7), 0x7d); /* DIO2_13 on IRQ6 */
        else if (priv->hwirq == 1)
                ts5500_clear_mask(BIT(6), 0x7d); /* LCD_RS on IRQ1 */
        else
                dev_err(priv->gpio_chip.parent, "invalid hwirq %d\n",
                        priv->hwirq);
        spin_unlock_irqrestore(&priv->lock, flags);
}

static int ts5500_dio_probe(struct platform_device *pdev)
{
        enum ts5500_blocks block = platform_get_device_id(pdev)->driver_data;
        struct device *dev = &pdev->dev;
        const char *name = dev_name(dev);
        struct ts5500_priv *priv;
        unsigned long flags;
        int ret;

        ret = platform_get_irq(pdev, 0);
        if (ret < 0)
                return ret;

        priv = devm_kzalloc(dev, sizeof(struct ts5500_priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        platform_set_drvdata(pdev, priv);
        priv->hwirq = ret;
        spin_lock_init(&priv->lock);

        priv->gpio_chip.owner = THIS_MODULE;
        priv->gpio_chip.label = name;
        priv->gpio_chip.parent = dev;
        priv->gpio_chip.direction_input = ts5500_gpio_input;
        priv->gpio_chip.direction_output = ts5500_gpio_output;
        priv->gpio_chip.get = ts5500_gpio_get;
        priv->gpio_chip.set = ts5500_gpio_set;
        priv->gpio_chip.to_irq = ts5500_gpio_to_irq;
        priv->gpio_chip.base = -1;

        switch (block) {
        case TS5500_DIO1:
                priv->pinout = ts5500_dio1;
                priv->gpio_chip.ngpio = ARRAY_SIZE(ts5500_dio1);

                if (!devm_request_region(dev, 0x7a, 3, name)) {
                        dev_err(dev, "failed to request %s ports\n", name);
                        return -EBUSY;
                }
                break;
        case TS5500_DIO2:
                priv->pinout = ts5500_dio2;
                priv->gpio_chip.ngpio = ARRAY_SIZE(ts5500_dio2);

                if (!devm_request_region(dev, 0x7e, 2, name)) {
                        dev_err(dev, "failed to request %s ports\n", name);
                        return -EBUSY;
                }

                if (hex7d_reserved)
                        break;

                if (!devm_request_region(dev, 0x7d, 1, name)) {
                        dev_err(dev, "failed to request %s 7D\n", name);
                        return -EBUSY;
                }

                hex7d_reserved = true;
                break;
        case TS5500_LCD:
        case TS5600_LCD:
                priv->pinout = ts5500_lcd;
                priv->gpio_chip.ngpio = ARRAY_SIZE(ts5500_lcd);

                if (!devm_request_region(dev, 0x72, 2, name)) {
                        dev_err(dev, "failed to request %s ports\n", name);
                        return -EBUSY;
                }

                if (!hex7d_reserved) {
                        if (!devm_request_region(dev, 0x7d, 1, name)) {
                                dev_err(dev, "failed to request %s 7D\n", name);
                                return -EBUSY;
                        }

                        hex7d_reserved = true;
                }

                /* Ensure usage of LCD port as DIO */
                spin_lock_irqsave(&priv->lock, flags);
                ts5500_clear_mask(BIT(4), 0x7d);
                spin_unlock_irqrestore(&priv->lock, flags);
                break;
        }

        ret = devm_gpiochip_add_data(dev, &priv->gpio_chip, priv);
        if (ret) {
                dev_err(dev, "failed to register the gpio chip\n");
                return ret;
        }

        ret = ts5500_enable_irq(priv);
        if (ret) {
                dev_err(dev, "invalid interrupt %d\n", priv->hwirq);
                return ret;
        }

        return 0;
}

static void ts5500_dio_remove(struct platform_device *pdev)
{
        struct ts5500_priv *priv = platform_get_drvdata(pdev);

        ts5500_disable_irq(priv);
}

static const struct platform_device_id ts5500_dio_ids[] = {
        { "ts5500-dio1", TS5500_DIO1 },
        { "ts5500-dio2", TS5500_DIO2 },
        { "ts5500-dio-lcd", TS5500_LCD },
        { "ts5600-dio-lcd", TS5600_LCD },
        { }
};
MODULE_DEVICE_TABLE(platform, ts5500_dio_ids);

static struct platform_driver ts5500_dio_driver = {
        .driver = {
                .name = "ts5500-dio",
        },
        .probe = ts5500_dio_probe,
        .remove = ts5500_dio_remove,
        .id_table = ts5500_dio_ids,
};

module_platform_driver(ts5500_dio_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Savoir-faire Linux Inc. <kernel@savoirfairelinux.com>");
MODULE_DESCRIPTION("Technologic Systems TS-5500 Digital I/O driver");