// SPDX-License-Identifier: GPL-2.0-only
/*
 * SDL Inc. RISCom/N2 synchronous serial card driver for Linux
 *
 * Copyright (C) 1998-2003 Krzysztof Halasa <khc@pm.waw.pl>
 *
 * For information see <https://www.kernel.org/pub/linux/utils/net/hdlc/>
 *
 * Note: integrated CSU/DSU/DDS are not supported by this driver
 *
 * Sources of information:
 *    Hitachi HD64570 SCA User's Manual
 *    SDL Inc. PPP/HDLC/CISCO driver
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/capability.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/in.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/moduleparam.h>
#include <linux/netdevice.h>
#include <linux/hdlc.h>
#include <asm/io.h>
#include "hd64570.h"

static const char *version = "SDL RISCom/N2 driver version: 1.15";
static const char *devname = "RISCom/N2";

#undef DEBUG_PKT
#define DEBUG_RINGS

#define USE_WINDOWSIZE 16384
#define USE_BUS16BITS 1
#define CLOCK_BASE 9830400      /* 9.8304 MHz */
#define MAX_PAGES      16       /* 16 RAM pages at max */
#define MAX_RAM_SIZE 0x80000    /* 512 KB */
#if MAX_RAM_SIZE > MAX_PAGES * USE_WINDOWSIZE
#undef MAX_RAM_SIZE
#define MAX_RAM_SIZE (MAX_PAGES * USE_WINDOWSIZE)
#endif
#define N2_IOPORTS 0x10
#define NEED_DETECT_RAM
#define NEED_SCA_MSCI_INTR
#define MAX_TX_BUFFERS 10

static char *hw;        /* pointer to hw=xxx command line string */

/* RISCom/N2 Board Registers */

/* PC Control Register */
#define N2_PCR 0
#define PCR_RUNSCA 1     /* Run 64570 */
#define PCR_VPM    2     /* Enable VPM - needed if using RAM above 1 MB */
#define PCR_ENWIN  4     /* Open window */
#define PCR_BUS16  8     /* 16-bit bus */

/* Memory Base Address Register */
#define N2_BAR 2

/* Page Scan Register  */
#define N2_PSR 4
#define WIN16K       0x00
#define WIN32K       0x20
#define WIN64K       0x40
#define PSR_WINBITS  0x60
#define PSR_DMAEN    0x80
#define PSR_PAGEBITS 0x0F

/* Modem Control Reg */
#define N2_MCR 6
#define CLOCK_OUT_PORT1 0x80
#define CLOCK_OUT_PORT0 0x40
#define TX422_PORT1     0x20
#define TX422_PORT0     0x10
#define DSR_PORT1       0x08
#define DSR_PORT0       0x04
#define DTR_PORT1       0x02
#define DTR_PORT0       0x01

typedef struct port_s {
        struct net_device *dev;
        struct card_s *card;
        spinlock_t lock;        /* TX lock */
        sync_serial_settings settings;
        int valid;              /* port enabled */
        int rxpart;             /* partial frame received, next frame invalid*/
        unsigned short encoding;
        unsigned short parity;
        u16 rxin;               /* rx ring buffer 'in' pointer */
        u16 txin;               /* tx ring buffer 'in' and 'last' pointers */
        u16 txlast;
        u8 rxs, txs, tmc;       /* SCA registers */
        u8 phy_node;            /* physical port # - 0 or 1 */
        u8 log_node;            /* logical port # */
} port_t;

typedef struct card_s {
        u8 __iomem *winbase;            /* ISA window base address */
        u32 phy_winbase;        /* ISA physical base address */
        u32 ram_size;           /* number of bytes */
        u16 io;                 /* IO Base address */
        u16 buff_offset;        /* offset of first buffer of first channel */
        u16 rx_ring_buffers;    /* number of buffers in a ring */
        u16 tx_ring_buffers;
        u8 irq;                 /* IRQ (3-15) */

        port_t ports[2];
        struct card_s *next_card;
} card_t;

static card_t *first_card;
static card_t **new_card = &first_card;

#define sca_reg(reg, card) (0x8000 | (card)->io | \
                            ((reg) & 0x0F) | (((reg) & 0xF0) << 6))
#define sca_in(reg, card)               inb(sca_reg(reg, card))
#define sca_out(value, reg, card)       outb(value, sca_reg(reg, card))
#define sca_inw(reg, card)              inw(sca_reg(reg, card))
#define sca_outw(value, reg, card)      outw(value, sca_reg(reg, card))

#define port_to_card(port)              ((port)->card)
#define log_node(port)                  ((port)->log_node)
#define phy_node(port)                  ((port)->phy_node)
#define winsize(card)                   (USE_WINDOWSIZE)
#define winbase(card)                   ((card)->winbase)
#define get_port(card, port)            ((card)->ports[port].valid ? \
                                         &(card)->ports[port] : NULL)

static __inline__ u8 sca_get_page(card_t *card)
{
        return inb(card->io + N2_PSR) & PSR_PAGEBITS;
}

static __inline__ void openwin(card_t *card, u8 page)
{
        u8 psr = inb(card->io + N2_PSR);

        outb((psr & ~PSR_PAGEBITS) | page, card->io + N2_PSR);
}

#include "hd64570.c"

static void n2_set_iface(port_t *port)
{
        card_t *card = port->card;
        int io = card->io;
        u8 mcr = inb(io + N2_MCR);
        u8 msci = get_msci(port);
        u8 rxs = port->rxs & CLK_BRG_MASK;
        u8 txs = port->txs & CLK_BRG_MASK;

        switch (port->settings.clock_type) {
        case CLOCK_INT:
                mcr |= port->phy_node ? CLOCK_OUT_PORT1 : CLOCK_OUT_PORT0;
                rxs |= CLK_BRG_RX; /* BRG output */
                txs |= CLK_RXCLK_TX; /* RX clock */
                break;

        case CLOCK_TXINT:
                mcr |= port->phy_node ? CLOCK_OUT_PORT1 : CLOCK_OUT_PORT0;
                rxs |= CLK_LINE_RX; /* RXC input */
                txs |= CLK_BRG_TX; /* BRG output */
                break;

        case CLOCK_TXFROMRX:
                mcr |= port->phy_node ? CLOCK_OUT_PORT1 : CLOCK_OUT_PORT0;
                rxs |= CLK_LINE_RX; /* RXC input */
                txs |= CLK_RXCLK_TX; /* RX clock */
                break;

        default:                /* Clock EXTernal */
                mcr &= port->phy_node ? ~CLOCK_OUT_PORT1 : ~CLOCK_OUT_PORT0;
                rxs |= CLK_LINE_RX; /* RXC input */
                txs |= CLK_LINE_TX; /* TXC input */
        }

        outb(mcr, io + N2_MCR);
        port->rxs = rxs;
        port->txs = txs;
        sca_out(rxs, msci + RXS, card);
        sca_out(txs, msci + TXS, card);
        sca_set_port(port);
}

static int n2_open(struct net_device *dev)
{
        port_t *port = dev_to_port(dev);
        int io = port->card->io;
        u8 mcr = inb(io + N2_MCR) |
                (port->phy_node ? TX422_PORT1 : TX422_PORT0);
        int result;

        result = hdlc_open(dev);
        if (result)
                return result;

        mcr &= port->phy_node ? ~DTR_PORT1 : ~DTR_PORT0; /* set DTR ON */
        outb(mcr, io + N2_MCR);

        outb(inb(io + N2_PCR) | PCR_ENWIN, io + N2_PCR); /* open window */
        outb(inb(io + N2_PSR) | PSR_DMAEN, io + N2_PSR); /* enable dma */
        sca_open(dev);
        n2_set_iface(port);
        return 0;
}

static int n2_close(struct net_device *dev)
{
        port_t *port = dev_to_port(dev);
        int io = port->card->io;
        u8 mcr = inb(io + N2_MCR) |
                (port->phy_node ? TX422_PORT1 : TX422_PORT0);

        sca_close(dev);
        mcr |= port->phy_node ? DTR_PORT1 : DTR_PORT0; /* set DTR OFF */
        outb(mcr, io + N2_MCR);
        hdlc_close(dev);
        return 0;
}

static int n2_siocdevprivate(struct net_device *dev, struct ifreq *ifr,
                             void __user *data, int cmd)
{
#ifdef DEBUG_RINGS
        if (cmd == SIOCDEVPRIVATE) {
                sca_dump_rings(dev);
                return 0;
        }
#endif
        return -EOPNOTSUPP;
}

static int n2_ioctl(struct net_device *dev, struct if_settings *ifs)
{
        const size_t size = sizeof(sync_serial_settings);
        sync_serial_settings new_line;
        sync_serial_settings __user *line = ifs->ifs_ifsu.sync;
        port_t *port = dev_to_port(dev);

        switch (ifs->type) {
        case IF_GET_IFACE:
                ifs->type = IF_IFACE_SYNC_SERIAL;
                if (ifs->size < size) {
                        ifs->size = size; /* data size wanted */
                        return -ENOBUFS;
                }
                if (copy_to_user(line, &port->settings, size))
                        return -EFAULT;
                return 0;

        case IF_IFACE_SYNC_SERIAL:
                if (!capable(CAP_NET_ADMIN))
                        return -EPERM;

                if (copy_from_user(&new_line, line, size))
                        return -EFAULT;

                if (new_line.clock_type != CLOCK_EXT &&
                    new_line.clock_type != CLOCK_TXFROMRX &&
                    new_line.clock_type != CLOCK_INT &&
                    new_line.clock_type != CLOCK_TXINT)
                        return -EINVAL; /* No such clock setting */

                if (new_line.loopback != 0 && new_line.loopback != 1)
                        return -EINVAL;

                memcpy(&port->settings, &new_line, size); /* Update settings */
                n2_set_iface(port);
                return 0;

        default:
                return hdlc_ioctl(dev, ifs);
        }
}

static void n2_destroy_card(card_t *card)
{
        int cnt;

        for (cnt = 0; cnt < 2; cnt++)
                if (card->ports[cnt].card) {
                        struct net_device *dev = port_to_dev(&card->ports[cnt]);

                        unregister_hdlc_device(dev);
                }

        if (card->irq)
                free_irq(card->irq, card);

        if (card->winbase) {
                iounmap(card->winbase);
                release_mem_region(card->phy_winbase, USE_WINDOWSIZE);
        }

        if (card->io)
                release_region(card->io, N2_IOPORTS);
        if (card->ports[0].dev)
                free_netdev(card->ports[0].dev);
        if (card->ports[1].dev)
                free_netdev(card->ports[1].dev);
        kfree(card);
}

static const struct net_device_ops n2_ops = {
        .ndo_open       = n2_open,
        .ndo_stop       = n2_close,
        .ndo_start_xmit = hdlc_start_xmit,
        .ndo_siocwandev = n2_ioctl,
        .ndo_siocdevprivate = n2_siocdevprivate,
};

static int __init n2_run(unsigned long io, unsigned long irq,
                         unsigned long winbase, long valid0, long valid1)
{
        card_t *card;
        u8 cnt, pcr;
        int i;

        if (io < 0x200 || io > 0x3FF || (io % N2_IOPORTS) != 0) {
                pr_err("invalid I/O port value\n");
                return -ENODEV;
        }

        if (irq < 3 || irq > 15 || irq == 6) /* FIXME */ {
                pr_err("invalid IRQ value\n");
                return -ENODEV;
        }

        if (winbase < 0xA0000 || winbase > 0xFFFFF || (winbase & 0xFFF) != 0) {
                pr_err("invalid RAM value\n");
                return -ENODEV;
        }

        card = kzalloc_obj(card_t);
        if (!card)
                return -ENOBUFS;

        card->ports[0].dev = alloc_hdlcdev(&card->ports[0]);
        card->ports[1].dev = alloc_hdlcdev(&card->ports[1]);
        if (!card->ports[0].dev || !card->ports[1].dev) {
                pr_err("unable to allocate memory\n");
                n2_destroy_card(card);
                return -ENOMEM;
        }

        if (!request_region(io, N2_IOPORTS, devname)) {
                pr_err("I/O port region in use\n");
                n2_destroy_card(card);
                return -EBUSY;
        }
        card->io = io;

        if (request_irq(irq, sca_intr, 0, devname, card)) {
                pr_err("could not allocate IRQ\n");
                n2_destroy_card(card);
                return -EBUSY;
        }
        card->irq = irq;

        if (!request_mem_region(winbase, USE_WINDOWSIZE, devname)) {
                pr_err("could not request RAM window\n");
                n2_destroy_card(card);
                return -EBUSY;
        }
        card->phy_winbase = winbase;
        card->winbase = ioremap(winbase, USE_WINDOWSIZE);
        if (!card->winbase) {
                pr_err("ioremap() failed\n");
                n2_destroy_card(card);
                return -EFAULT;
        }

        outb(0, io + N2_PCR);
        outb(winbase >> 12, io + N2_BAR);

        switch (USE_WINDOWSIZE) {
        case 16384:
                outb(WIN16K, io + N2_PSR);
                break;

        case 32768:
                outb(WIN32K, io + N2_PSR);
                break;

        case 65536:
                outb(WIN64K, io + N2_PSR);
                break;

        default:
                pr_err("invalid window size\n");
                n2_destroy_card(card);
                return -ENODEV;
        }

        pcr = PCR_ENWIN | PCR_VPM | (USE_BUS16BITS ? PCR_BUS16 : 0);
        outb(pcr, io + N2_PCR);

        card->ram_size = sca_detect_ram(card, card->winbase, MAX_RAM_SIZE);

        /* number of TX + RX buffers for one port */
        i = card->ram_size / ((valid0 + valid1) * (sizeof(pkt_desc) +
                                                   HDLC_MAX_MRU));

        card->tx_ring_buffers = min(i / 2, MAX_TX_BUFFERS);
        card->rx_ring_buffers = i - card->tx_ring_buffers;

        card->buff_offset = (valid0 + valid1) * sizeof(pkt_desc) *
                (card->tx_ring_buffers + card->rx_ring_buffers);

        pr_info("RISCom/N2 %u KB RAM, IRQ%u, using %u TX + %u RX packets rings\n",
                card->ram_size / 1024, card->irq,
                card->tx_ring_buffers, card->rx_ring_buffers);

        if (card->tx_ring_buffers < 1) {
                pr_err("RAM test failed\n");
                n2_destroy_card(card);
                return -EIO;
        }

        pcr |= PCR_RUNSCA;              /* run SCA */
        outb(pcr, io + N2_PCR);
        outb(0, io + N2_MCR);

        sca_init(card, 0);
        for (cnt = 0; cnt < 2; cnt++) {
                port_t *port = &card->ports[cnt];
                struct net_device *dev = port_to_dev(port);
                hdlc_device *hdlc = dev_to_hdlc(dev);

                if ((cnt == 0 && !valid0) || (cnt == 1 && !valid1))
                        continue;

                port->phy_node = cnt;
                port->valid = 1;

                if ((cnt == 1) && valid0)
                        port->log_node = 1;

                spin_lock_init(&port->lock);
                dev->irq = irq;
                dev->mem_start = winbase;
                dev->mem_end = winbase + USE_WINDOWSIZE - 1;
                dev->tx_queue_len = 50;
                dev->netdev_ops = &n2_ops;
                hdlc->attach = sca_attach;
                hdlc->xmit = sca_xmit;
                port->settings.clock_type = CLOCK_EXT;
                port->card = card;

                if (register_hdlc_device(dev)) {
                        pr_warn("unable to register hdlc device\n");
                        port->card = NULL;
                        n2_destroy_card(card);
                        return -ENOBUFS;
                }
                sca_init_port(port); /* Set up SCA memory */

                netdev_info(dev, "RISCom/N2 node %d\n", port->phy_node);
        }

        *new_card = card;
        new_card = &card->next_card;

        return 0;
}

static int __init n2_init(void)
{
        if (!hw) {
#ifdef MODULE
                pr_info("no card initialized\n");
#endif
                return -EINVAL; /* no parameters specified, abort */
        }

        pr_info("%s\n", version);

        do {
                unsigned long io, irq, ram;
                long valid[2] = { 0, 0 }; /* Default = both ports disabled */

                io = simple_strtoul(hw, &hw, 0);

                if (*hw++ != ',')
                        break;
                irq = simple_strtoul(hw, &hw, 0);

                if (*hw++ != ',')
                        break;
                ram = simple_strtoul(hw, &hw, 0);

                if (*hw++ != ',')
                        break;
                while (1) {
                        if (*hw == '0' && !valid[0])
                                valid[0] = 1; /* Port 0 enabled */
                        else if (*hw == '1' && !valid[1])
                                valid[1] = 1; /* Port 1 enabled */
                        else
                                break;
                        hw++;
                }

                if (!valid[0] && !valid[1])
                        break;  /* at least one port must be used */

                if (*hw == ':' || *hw == '\x0')
                        n2_run(io, irq, ram, valid[0], valid[1]);

                if (*hw == '\x0')
                        return first_card ? 0 : -EINVAL;
        } while (*hw++ == ':');

        pr_err("invalid hardware parameters\n");
        return first_card ? 0 : -EINVAL;
}

static void __exit n2_cleanup(void)
{
        card_t *card = first_card;

        while (card) {
                card_t *ptr = card;

                card = card->next_card;
                n2_destroy_card(ptr);
        }
}

module_init(n2_init);
module_exit(n2_cleanup);

MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
MODULE_DESCRIPTION("RISCom/N2 serial port driver");
MODULE_LICENSE("GPL v2");
module_param(hw, charp, 0444);
MODULE_PARM_DESC(hw, "io,irq,ram,ports:io,irq,...");