// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Xilinx XPS PS/2 device driver
 *
 * (c) 2005 MontaVista Software, Inc.
 * (c) 2008 Xilinx, Inc.
 */


#include <linux/module.h>
#include <linux/serio.h>
#include <linux/interrupt.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/io.h>
#include <linux/mod_devicetable.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/platform_device.h>

#define DRIVER_NAME             "xilinx_ps2"

/* Register offsets for the xps2 device */
#define XPS2_SRST_OFFSET        0x00000000 /* Software Reset register */
#define XPS2_STATUS_OFFSET      0x00000004 /* Status register */
#define XPS2_RX_DATA_OFFSET     0x00000008 /* Receive Data register */
#define XPS2_TX_DATA_OFFSET     0x0000000C /* Transmit Data register */
#define XPS2_GIER_OFFSET        0x0000002C /* Global Interrupt Enable reg */
#define XPS2_IPISR_OFFSET       0x00000030 /* Interrupt Status register */
#define XPS2_IPIER_OFFSET       0x00000038 /* Interrupt Enable register */

/* Reset Register Bit Definitions */
#define XPS2_SRST_RESET         0x0000000A /* Software Reset  */

/* Status Register Bit Positions */
#define XPS2_STATUS_RX_FULL     0x00000001 /* Receive Full  */
#define XPS2_STATUS_TX_FULL     0x00000002 /* Transmit Full  */

/*
 * Bit definitions for ISR/IER registers. Both the registers have the same bit
 * definitions and are only defined once.
 */
#define XPS2_IPIXR_WDT_TOUT     0x00000001 /* Watchdog Timeout Interrupt */
#define XPS2_IPIXR_TX_NOACK     0x00000002 /* Transmit No ACK Interrupt */
#define XPS2_IPIXR_TX_ACK       0x00000004 /* Transmit ACK (Data) Interrupt */
#define XPS2_IPIXR_RX_OVF       0x00000008 /* Receive Overflow Interrupt */
#define XPS2_IPIXR_RX_ERR       0x00000010 /* Receive Error Interrupt */
#define XPS2_IPIXR_RX_FULL      0x00000020 /* Receive Data Interrupt */

/* Mask for all the Transmit Interrupts */
#define XPS2_IPIXR_TX_ALL       (XPS2_IPIXR_TX_NOACK | XPS2_IPIXR_TX_ACK)

/* Mask for all the Receive Interrupts */
#define XPS2_IPIXR_RX_ALL       (XPS2_IPIXR_RX_OVF | XPS2_IPIXR_RX_ERR |  \
                                 XPS2_IPIXR_RX_FULL)

/* Mask for all the Interrupts */
#define XPS2_IPIXR_ALL          (XPS2_IPIXR_TX_ALL | XPS2_IPIXR_RX_ALL |  \
                                 XPS2_IPIXR_WDT_TOUT)

/* Global Interrupt Enable mask */
#define XPS2_GIER_GIE_MASK      0x80000000

struct xps2data {
        int irq;
        spinlock_t lock;
        void __iomem *base_address;     /* virt. address of control registers */
        unsigned int flags;
        struct serio *serio;            /* serio */
        struct device *dev;
};

/************************************/
/* XPS PS/2 data transmission calls */
/************************************/

/**
 * xps2_recv() - attempts to receive a byte from the PS/2 port.
 * @drvdata:    pointer to ps2 device private data structure
 * @byte:       address where the read data will be copied
 *
 * If there is any data available in the PS/2 receiver, this functions reads
 * the data, otherwise it returns error.
 */
static int xps2_recv(struct xps2data *drvdata, u8 *byte)
{
        u32 sr;
        int status = -1;

        /* If there is data available in the PS/2 receiver, read it */
        sr = in_be32(drvdata->base_address + XPS2_STATUS_OFFSET);
        if (sr & XPS2_STATUS_RX_FULL) {
                *byte = in_be32(drvdata->base_address + XPS2_RX_DATA_OFFSET);
                status = 0;
        }

        return status;
}

/*********************/
/* Interrupt handler */
/*********************/
static irqreturn_t xps2_interrupt(int irq, void *dev_id)
{
        struct xps2data *drvdata = dev_id;
        u32 intr_sr;
        u8 c;
        int status;

        /* Get the PS/2 interrupts and clear them */
        intr_sr = in_be32(drvdata->base_address + XPS2_IPISR_OFFSET);
        out_be32(drvdata->base_address + XPS2_IPISR_OFFSET, intr_sr);

        /* Check which interrupt is active */
        if (intr_sr & XPS2_IPIXR_RX_OVF)
                dev_warn(drvdata->dev, "receive overrun error\n");

        if (intr_sr & XPS2_IPIXR_RX_ERR)
                drvdata->flags |= SERIO_PARITY;

        if (intr_sr & (XPS2_IPIXR_TX_NOACK | XPS2_IPIXR_WDT_TOUT))
                drvdata->flags |= SERIO_TIMEOUT;

        if (intr_sr & XPS2_IPIXR_RX_FULL) {
                status = xps2_recv(drvdata, &c);

                /* Error, if a byte is not received */
                if (status) {
                        dev_err(drvdata->dev,
                                "wrong rcvd byte count (%d)\n", status);
                } else {
                        serio_interrupt(drvdata->serio, c, drvdata->flags);
                        drvdata->flags = 0;
                }
        }

        return IRQ_HANDLED;
}

/*******************/
/* serio callbacks */
/*******************/

/**
 * sxps2_write() - sends a byte out through the PS/2 port.
 * @pserio:     pointer to the serio structure of the PS/2 port
 * @c:          data that needs to be written to the PS/2 port
 *
 * This function checks if the PS/2 transmitter is empty and sends a byte.
 * Otherwise it returns error. Transmission fails only when nothing is connected
 * to the PS/2 port. Thats why, we do not try to resend the data in case of a
 * failure.
 */
static int sxps2_write(struct serio *pserio, unsigned char c)
{
        struct xps2data *drvdata = pserio->port_data;
        u32 sr;

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

        /* If the PS/2 transmitter is empty send a byte of data */
        sr = in_be32(drvdata->base_address + XPS2_STATUS_OFFSET);
        if (sr & XPS2_STATUS_TX_FULL)
                return -EAGAIN;

        out_be32(drvdata->base_address + XPS2_TX_DATA_OFFSET, c);
        return 0;
}

/**
 * sxps2_open() - called when a port is opened by the higher layer.
 * @pserio:     pointer to the serio structure of the PS/2 device
 *
 * This function requests irq and enables interrupts for the PS/2 device.
 */
static int sxps2_open(struct serio *pserio)
{
        struct xps2data *drvdata = pserio->port_data;
        int error;
        u8 c;

        error = request_irq(drvdata->irq, &xps2_interrupt, 0,
                                DRIVER_NAME, drvdata);
        if (error) {
                dev_err(drvdata->dev,
                        "Couldn't allocate interrupt %d\n", drvdata->irq);
                return error;
        }

        /* start reception by enabling the interrupts */
        out_be32(drvdata->base_address + XPS2_GIER_OFFSET, XPS2_GIER_GIE_MASK);
        out_be32(drvdata->base_address + XPS2_IPIER_OFFSET, XPS2_IPIXR_RX_ALL);
        (void)xps2_recv(drvdata, &c);

        return 0;               /* success */
}

/**
 * sxps2_close() - frees the interrupt.
 * @pserio:     pointer to the serio structure of the PS/2 device
 *
 * This function frees the irq and disables interrupts for the PS/2 device.
 */
static void sxps2_close(struct serio *pserio)
{
        struct xps2data *drvdata = pserio->port_data;

        /* Disable the PS2 interrupts */
        out_be32(drvdata->base_address + XPS2_GIER_OFFSET, 0x00);
        out_be32(drvdata->base_address + XPS2_IPIER_OFFSET, 0x00);
        free_irq(drvdata->irq, drvdata);
}

/**
 * xps2_of_probe - probe method for the PS/2 device.
 * @ofdev:      pointer to OF device structure
 *
 * This function probes the PS/2 device in the device tree.
 * It initializes the driver data structure and the hardware.
 * It returns 0, if the driver is bound to the PS/2 device, or a negative
 * value if there is an error.
 */
static int xps2_of_probe(struct platform_device *ofdev)
{
        struct resource r_mem; /* IO mem resources */
        struct xps2data *drvdata;
        struct serio *serio;
        struct device *dev = &ofdev->dev;
        resource_size_t remap_size, phys_addr;
        unsigned int irq;
        int error;

        dev_info(dev, "Device Tree Probing \'%pOFn\'\n", dev->of_node);

        /* Get iospace for the device */
        error = of_address_to_resource(dev->of_node, 0, &r_mem);
        if (error) {
                dev_err(dev, "invalid address\n");
                return error;
        }

        /* Get IRQ for the device */
        irq = irq_of_parse_and_map(dev->of_node, 0);
        if (!irq) {
                dev_err(dev, "no IRQ found\n");
                return -ENODEV;
        }

        drvdata = kzalloc_obj(*drvdata);
        serio = kzalloc_obj(*serio);
        if (!drvdata || !serio) {
                error = -ENOMEM;
                goto failed1;
        }

        spin_lock_init(&drvdata->lock);
        drvdata->irq = irq;
        drvdata->serio = serio;
        drvdata->dev = dev;

        phys_addr = r_mem.start;
        remap_size = resource_size(&r_mem);
        if (!request_mem_region(phys_addr, remap_size, DRIVER_NAME)) {
                dev_err(dev, "Couldn't lock memory region at 0x%08llX\n",
                        (unsigned long long)phys_addr);
                error = -EBUSY;
                goto failed1;
        }

        /* Fill in configuration data and add them to the list */
        drvdata->base_address = ioremap(phys_addr, remap_size);
        if (drvdata->base_address == NULL) {
                dev_err(dev, "Couldn't ioremap memory at 0x%08llX\n",
                        (unsigned long long)phys_addr);
                error = -EFAULT;
                goto failed2;
        }

        /* Disable all the interrupts, just in case */
        out_be32(drvdata->base_address + XPS2_IPIER_OFFSET, 0);

        /*
         * Reset the PS2 device and abort any current transaction,
         * to make sure we have the PS2 in a good state.
         */
        out_be32(drvdata->base_address + XPS2_SRST_OFFSET, XPS2_SRST_RESET);

        dev_info(dev, "Xilinx PS2 at 0x%08llX mapped to 0x%p, irq=%d\n",
                 (unsigned long long)phys_addr, drvdata->base_address,
                 drvdata->irq);

        serio->id.type = SERIO_8042;
        serio->write = sxps2_write;
        serio->open = sxps2_open;
        serio->close = sxps2_close;
        serio->port_data = drvdata;
        serio->dev.parent = dev;
        snprintf(serio->name, sizeof(serio->name),
                 "Xilinx XPS PS/2 at %08llX", (unsigned long long)phys_addr);
        snprintf(serio->phys, sizeof(serio->phys),
                 "xilinxps2/serio at %08llX", (unsigned long long)phys_addr);

        serio_register_port(serio);

        platform_set_drvdata(ofdev, drvdata);
        return 0;               /* success */

failed2:
        release_mem_region(phys_addr, remap_size);
failed1:
        kfree(serio);
        kfree(drvdata);

        return error;
}

/**
 * xps2_of_remove - unbinds the driver from the PS/2 device.
 * @of_dev:     pointer to OF device structure
 *
 * This function is called if a device is physically removed from the system or
 * if the driver module is being unloaded. It frees any resources allocated to
 * the device.
 */
static void xps2_of_remove(struct platform_device *of_dev)
{
        struct xps2data *drvdata = platform_get_drvdata(of_dev);
        struct resource r_mem; /* IO mem resources */

        serio_unregister_port(drvdata->serio);
        iounmap(drvdata->base_address);

        /* Get iospace of the device */
        if (of_address_to_resource(of_dev->dev.of_node, 0, &r_mem))
                dev_err(drvdata->dev, "invalid address\n");
        else
                release_mem_region(r_mem.start, resource_size(&r_mem));

        kfree(drvdata);
}

/* Match table for of_platform binding */
static const struct of_device_id xps2_of_match[] = {
        { .compatible = "xlnx,xps-ps2-1.00.a", },
        { /* end of list */ },
};
MODULE_DEVICE_TABLE(of, xps2_of_match);

static struct platform_driver xps2_of_driver = {
        .driver = {
                .name = DRIVER_NAME,
                .of_match_table = xps2_of_match,
        },
        .probe          = xps2_of_probe,
        .remove         = xps2_of_remove,
};
module_platform_driver(xps2_of_driver);

MODULE_AUTHOR("Xilinx, Inc.");
MODULE_DESCRIPTION("Xilinx XPS PS/2 driver");
MODULE_LICENSE("GPL");