// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2013 Aeroflex Gaisler
 *
 * This driver supports the APBPS2 PS/2 core available in the GRLIB
 * VHDL IP core library.
 *
 * Full documentation of the APBPS2 core can be found here:
 * http://www.gaisler.com/products/grlib/grip.pdf
 *
 * See "Documentation/devicetree/bindings/input/ps2keyb-mouse-apbps2.txt" for
 * information on open firmware properties.
 *
 * Contributors: Daniel Hellstrom <daniel@gaisler.com>
 */
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/serio.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/io.h>

struct apbps2_regs {
        u32 __iomem data;       /* 0x00 */
        u32 __iomem status;     /* 0x04 */
        u32 __iomem ctrl;       /* 0x08 */
        u32 __iomem reload;     /* 0x0c */
};

#define APBPS2_STATUS_DR        (1<<0)
#define APBPS2_STATUS_PE        (1<<1)
#define APBPS2_STATUS_FE        (1<<2)
#define APBPS2_STATUS_KI        (1<<3)
#define APBPS2_STATUS_RF        (1<<4)
#define APBPS2_STATUS_TF        (1<<5)
#define APBPS2_STATUS_TCNT      (0x1f<<22)
#define APBPS2_STATUS_RCNT      (0x1f<<27)

#define APBPS2_CTRL_RE          (1<<0)
#define APBPS2_CTRL_TE          (1<<1)
#define APBPS2_CTRL_RI          (1<<2)
#define APBPS2_CTRL_TI          (1<<3)

struct apbps2_priv {
        struct serio            *io;
        struct apbps2_regs      __iomem *regs;
};

static int apbps2_idx;

static irqreturn_t apbps2_isr(int irq, void *dev_id)
{
        struct apbps2_priv *priv = dev_id;
        unsigned long status, data, rxflags;
        irqreturn_t ret = IRQ_NONE;

        while ((status = ioread32be(&priv->regs->status)) & APBPS2_STATUS_DR) {
                data = ioread32be(&priv->regs->data);
                rxflags = (status & APBPS2_STATUS_PE) ? SERIO_PARITY : 0;
                rxflags |= (status & APBPS2_STATUS_FE) ? SERIO_FRAME : 0;

                /* Clear error bits */
                if (rxflags)
                        iowrite32be(0, &priv->regs->status);

                serio_interrupt(priv->io, data, rxflags);

                ret = IRQ_HANDLED;
        }

        return ret;
}

static int apbps2_write(struct serio *io, unsigned char val)
{
        struct apbps2_priv *priv = io->port_data;
        unsigned int tleft = 10000; /* Timeout in 100ms */

        /* Delay until PS/2 controller has room for more chars */
        while ((ioread32be(&priv->regs->status) & APBPS2_STATUS_TF) && tleft--)
                udelay(10);

        if ((ioread32be(&priv->regs->status) & APBPS2_STATUS_TF) == 0) {
                iowrite32be(val, &priv->regs->data);

                iowrite32be(APBPS2_CTRL_RE | APBPS2_CTRL_RI | APBPS2_CTRL_TE,
                                &priv->regs->ctrl);
                return 0;
        }

        return -ETIMEDOUT;
}

static int apbps2_open(struct serio *io)
{
        struct apbps2_priv *priv = io->port_data;
        int limit;

        /* Clear error flags */
        iowrite32be(0, &priv->regs->status);

        /* Clear old data if available (unlikely) */
        limit = 1024;
        while ((ioread32be(&priv->regs->status) & APBPS2_STATUS_DR) && --limit)
                ioread32be(&priv->regs->data);

        /* Enable receiver and its interrupt */
        iowrite32be(APBPS2_CTRL_RE | APBPS2_CTRL_RI, &priv->regs->ctrl);

        return 0;
}

static void apbps2_close(struct serio *io)
{
        struct apbps2_priv *priv = io->port_data;

        /* Stop interrupts at PS/2 HW level */
        iowrite32be(0, &priv->regs->ctrl);
}

/* Initialize one APBPS2 PS/2 core */
static int apbps2_of_probe(struct platform_device *ofdev)
{
        struct apbps2_priv *priv;
        int irq, err;
        u32 freq_hz;

        priv = devm_kzalloc(&ofdev->dev, sizeof(*priv), GFP_KERNEL);
        if (!priv) {
                dev_err(&ofdev->dev, "memory allocation failed\n");
                return -ENOMEM;
        }

        /* Find device address */
        priv->regs = devm_platform_get_and_ioremap_resource(ofdev, 0, NULL);
        if (IS_ERR(priv->regs))
                return PTR_ERR(priv->regs);

        /* Reset hardware, disable interrupt */
        iowrite32be(0, &priv->regs->ctrl);

        /* IRQ */
        irq = irq_of_parse_and_map(ofdev->dev.of_node, 0);
        err = devm_request_irq(&ofdev->dev, irq, apbps2_isr,
                                IRQF_SHARED, "apbps2", priv);
        if (err) {
                dev_err(&ofdev->dev, "request IRQ%d failed\n", irq);
                return err;
        }

        /* Get core frequency */
        if (of_property_read_u32(ofdev->dev.of_node, "freq", &freq_hz)) {
                dev_err(&ofdev->dev, "unable to get core frequency\n");
                return -EINVAL;
        }

        /* Set reload register to core freq in kHz/10 */
        iowrite32be(freq_hz / 10000, &priv->regs->reload);

        priv->io = kzalloc_obj(*priv->io);
        if (!priv->io)
                return -ENOMEM;

        priv->io->id.type = SERIO_8042;
        priv->io->open = apbps2_open;
        priv->io->close = apbps2_close;
        priv->io->write = apbps2_write;
        priv->io->port_data = priv;
        strscpy(priv->io->name, "APBPS2 PS/2", sizeof(priv->io->name));
        snprintf(priv->io->phys, sizeof(priv->io->phys),
                 "apbps2_%d", apbps2_idx++);

        dev_info(&ofdev->dev, "irq = %d, base = 0x%p\n", irq, priv->regs);

        serio_register_port(priv->io);

        platform_set_drvdata(ofdev, priv);

        return 0;
}

static void apbps2_of_remove(struct platform_device *of_dev)
{
        struct apbps2_priv *priv = platform_get_drvdata(of_dev);

        serio_unregister_port(priv->io);
}

static const struct of_device_id apbps2_of_match[] = {
        { .name = "GAISLER_APBPS2", },
        { .name = "01_060", },
        {}
};

MODULE_DEVICE_TABLE(of, apbps2_of_match);

static struct platform_driver apbps2_of_driver = {
        .driver = {
                .name = "grlib-apbps2",
                .of_match_table = apbps2_of_match,
        },
        .probe = apbps2_of_probe,
        .remove = apbps2_of_remove,
};

module_platform_driver(apbps2_of_driver);

MODULE_AUTHOR("Aeroflex Gaisler AB.");
MODULE_DESCRIPTION("GRLIB APBPS2 PS/2 serial I/O");
MODULE_LICENSE("GPL");