// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/drivers/input/serio/sa1111ps2.c
 *
 *  Copyright (C) 2002 Russell King
 */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/input.h>
#include <linux/serio.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

#include <asm/io.h>

#include <asm/hardware/sa1111.h>

#define PS2CR           0x0000
#define PS2STAT         0x0004
#define PS2DATA         0x0008
#define PS2CLKDIV       0x000c
#define PS2PRECNT       0x0010

#define PS2CR_ENA       0x08
#define PS2CR_FKD       0x02
#define PS2CR_FKC       0x01

#define PS2STAT_STP     0x0100
#define PS2STAT_TXE     0x0080
#define PS2STAT_TXB     0x0040
#define PS2STAT_RXF     0x0020
#define PS2STAT_RXB     0x0010
#define PS2STAT_ENA     0x0008
#define PS2STAT_RXP     0x0004
#define PS2STAT_KBD     0x0002
#define PS2STAT_KBC     0x0001

struct ps2if {
        struct serio            *io;
        struct sa1111_dev       *dev;
        void __iomem            *base;
        int                     rx_irq;
        int                     tx_irq;
        unsigned int            open;
        spinlock_t              lock;
        unsigned int            head;
        unsigned int            tail;
        unsigned char           buf[4];
};

/*
 * Read all bytes waiting in the PS2 port.  There should be
 * at the most one, but we loop for safety.  If there was a
 * framing error, we have to manually clear the status.
 */
static irqreturn_t ps2_rxint(int irq, void *dev_id)
{
        struct ps2if *ps2if = dev_id;
        unsigned int scancode, flag, status;

        status = readl_relaxed(ps2if->base + PS2STAT);
        while (status & PS2STAT_RXF) {
                if (status & PS2STAT_STP)
                        writel_relaxed(PS2STAT_STP, ps2if->base + PS2STAT);

                flag = (status & PS2STAT_STP ? SERIO_FRAME : 0) |
                       (status & PS2STAT_RXP ? 0 : SERIO_PARITY);

                scancode = readl_relaxed(ps2if->base + PS2DATA) & 0xff;

                if (hweight8(scancode) & 1)
                        flag ^= SERIO_PARITY;

                serio_interrupt(ps2if->io, scancode, flag);

                status = readl_relaxed(ps2if->base + PS2STAT);
        }

        return IRQ_HANDLED;
}

/*
 * Completion of ps2 write
 */
static irqreturn_t ps2_txint(int irq, void *dev_id)
{
        struct ps2if *ps2if = dev_id;
        unsigned int status;

        guard(spinlock)(&ps2if->lock);

        status = readl_relaxed(ps2if->base + PS2STAT);
        if (ps2if->head == ps2if->tail) {
                disable_irq_nosync(irq);
                /* done */
        } else if (status & PS2STAT_TXE) {
                writel_relaxed(ps2if->buf[ps2if->tail], ps2if->base + PS2DATA);
                ps2if->tail = (ps2if->tail + 1) & (sizeof(ps2if->buf) - 1);
        }

        return IRQ_HANDLED;
}

/*
 * Write a byte to the PS2 port.  We have to wait for the
 * port to indicate that the transmitter is empty.
 */
static int ps2_write(struct serio *io, unsigned char val)
{
        struct ps2if *ps2if = io->port_data;
        unsigned int head;

        guard(spinlock_irqsave)(&ps2if->lock);

        /*
         * If the TX register is empty, we can go straight out.
         */
        if (readl_relaxed(ps2if->base + PS2STAT) & PS2STAT_TXE) {
                writel_relaxed(val, ps2if->base + PS2DATA);
        } else {
                if (ps2if->head == ps2if->tail)
                        enable_irq(ps2if->tx_irq);
                head = (ps2if->head + 1) & (sizeof(ps2if->buf) - 1);
                if (head != ps2if->tail) {
                        ps2if->buf[ps2if->head] = val;
                        ps2if->head = head;
                }
        }

        return 0;
}

static int ps2_open(struct serio *io)
{
        struct ps2if *ps2if = io->port_data;
        int ret;

        ret = sa1111_enable_device(ps2if->dev);
        if (ret)
                return ret;

        ret = request_irq(ps2if->rx_irq, ps2_rxint, 0,
                          SA1111_DRIVER_NAME(ps2if->dev), ps2if);
        if (ret) {
                printk(KERN_ERR "sa1111ps2: could not allocate IRQ%d: %d\n",
                        ps2if->rx_irq, ret);
                sa1111_disable_device(ps2if->dev);
                return ret;
        }

        ret = request_irq(ps2if->tx_irq, ps2_txint, 0,
                          SA1111_DRIVER_NAME(ps2if->dev), ps2if);
        if (ret) {
                printk(KERN_ERR "sa1111ps2: could not allocate IRQ%d: %d\n",
                        ps2if->tx_irq, ret);
                free_irq(ps2if->rx_irq, ps2if);
                sa1111_disable_device(ps2if->dev);
                return ret;
        }

        ps2if->open = 1;

        enable_irq_wake(ps2if->rx_irq);

        writel_relaxed(PS2CR_ENA, ps2if->base + PS2CR);
        return 0;
}

static void ps2_close(struct serio *io)
{
        struct ps2if *ps2if = io->port_data;

        writel_relaxed(0, ps2if->base + PS2CR);

        disable_irq_wake(ps2if->rx_irq);

        ps2if->open = 0;

        free_irq(ps2if->tx_irq, ps2if);
        free_irq(ps2if->rx_irq, ps2if);

        sa1111_disable_device(ps2if->dev);
}

/*
 * Clear the input buffer.
 */
static void ps2_clear_input(struct ps2if *ps2if)
{
        int maxread = 100;

        while (maxread--) {
                if ((readl_relaxed(ps2if->base + PS2DATA) & 0xff) == 0xff)
                        break;
        }
}

static unsigned int ps2_test_one(struct ps2if *ps2if,
                                           unsigned int mask)
{
        unsigned int val;

        writel_relaxed(PS2CR_ENA | mask, ps2if->base + PS2CR);

        udelay(10);

        val = readl_relaxed(ps2if->base + PS2STAT);
        return val & (PS2STAT_KBC | PS2STAT_KBD);
}

/*
 * Test the keyboard interface.  We basically check to make sure that
 * we can drive each line to the keyboard independently of each other.
 */
static int ps2_test(struct ps2if *ps2if)
{
        unsigned int stat;
        int ret = 0;

        stat = ps2_test_one(ps2if, PS2CR_FKC);
        if (stat != PS2STAT_KBD) {
                printk("PS/2 interface test failed[1]: %02x\n", stat);
                ret = -ENODEV;
        }

        stat = ps2_test_one(ps2if, 0);
        if (stat != (PS2STAT_KBC | PS2STAT_KBD)) {
                printk("PS/2 interface test failed[2]: %02x\n", stat);
                ret = -ENODEV;
        }

        stat = ps2_test_one(ps2if, PS2CR_FKD);
        if (stat != PS2STAT_KBC) {
                printk("PS/2 interface test failed[3]: %02x\n", stat);
                ret = -ENODEV;
        }

        writel_relaxed(0, ps2if->base + PS2CR);

        return ret;
}

/*
 * Add one device to this driver.
 */
static int ps2_probe(struct sa1111_dev *dev)
{
        struct ps2if *ps2if;
        struct serio *serio;
        int ret;

        ps2if = kzalloc_obj(*ps2if);
        serio = kzalloc_obj(*serio);
        if (!ps2if || !serio) {
                ret = -ENOMEM;
                goto free;
        }

        serio->id.type          = SERIO_8042;
        serio->write            = ps2_write;
        serio->open             = ps2_open;
        serio->close            = ps2_close;
        strscpy(serio->name, dev_name(&dev->dev), sizeof(serio->name));
        strscpy(serio->phys, dev_name(&dev->dev), sizeof(serio->phys));
        serio->port_data        = ps2if;
        serio->dev.parent       = &dev->dev;
        ps2if->io               = serio;
        ps2if->dev              = dev;
        sa1111_set_drvdata(dev, ps2if);

        spin_lock_init(&ps2if->lock);

        ps2if->rx_irq = sa1111_get_irq(dev, 0);
        if (ps2if->rx_irq <= 0) {
                ret = ps2if->rx_irq ? : -ENXIO;
                goto free;
        }

        ps2if->tx_irq = sa1111_get_irq(dev, 1);
        if (ps2if->tx_irq <= 0) {
                ret = ps2if->tx_irq ? : -ENXIO;
                goto free;
        }

        /*
         * Request the physical region for this PS2 port.
         */
        if (!request_mem_region(dev->res.start,
                                dev->res.end - dev->res.start + 1,
                                SA1111_DRIVER_NAME(dev))) {
                ret = -EBUSY;
                goto free;
        }

        /*
         * Our parent device has already mapped the region.
         */
        ps2if->base = dev->mapbase;

        sa1111_enable_device(ps2if->dev);

        /* Incoming clock is 8MHz */
        writel_relaxed(0, ps2if->base + PS2CLKDIV);
        writel_relaxed(127, ps2if->base + PS2PRECNT);

        /*
         * Flush any pending input.
         */
        ps2_clear_input(ps2if);

        /*
         * Test the keyboard interface.
         */
        ret = ps2_test(ps2if);
        if (ret)
                goto out;

        /*
         * Flush any pending input.
         */
        ps2_clear_input(ps2if);

        sa1111_disable_device(ps2if->dev);
        serio_register_port(ps2if->io);
        return 0;

 out:
        sa1111_disable_device(ps2if->dev);
        release_mem_region(dev->res.start, resource_size(&dev->res));
 free:
        sa1111_set_drvdata(dev, NULL);
        kfree(ps2if);
        kfree(serio);
        return ret;
}

/*
 * Remove one device from this driver.
 */
static void ps2_remove(struct sa1111_dev *dev)
{
        struct ps2if *ps2if = sa1111_get_drvdata(dev);

        serio_unregister_port(ps2if->io);
        release_mem_region(dev->res.start, resource_size(&dev->res));
        sa1111_set_drvdata(dev, NULL);

        kfree(ps2if);
}

/*
 * Our device driver structure
 */
static struct sa1111_driver ps2_driver = {
        .drv = {
                .name   = "sa1111-ps2",
                .owner  = THIS_MODULE,
        },
        .devid          = SA1111_DEVID_PS2,
        .probe          = ps2_probe,
        .remove         = ps2_remove,
};

static int __init ps2_init(void)
{
        return sa1111_driver_register(&ps2_driver);
}

static void __exit ps2_exit(void)
{
        sa1111_driver_unregister(&ps2_driver);
}

module_init(ps2_init);
module_exit(ps2_exit);

MODULE_AUTHOR("Russell King <rmk@arm.linux.org.uk>");
MODULE_DESCRIPTION("SA1111 PS2 controller driver");
MODULE_LICENSE("GPL");