// SPDX-License-Identifier: GPL-2.0-only
/*
 * CAN driver for PEAK-System PCAN-PC Card
 * Derived from the PCAN project file driver/src/pcan_pccard.c
 *
 * Copyright (C) 2006-2025 PEAK System-Technik GmbH
 * Author: Stéphane Grosjean <stephane.grosjean@hms-networks.com>
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/netdevice.h>
#include <linux/delay.h>
#include <linux/timer.h>
#include <linux/io.h>
#include <pcmcia/cistpl.h>
#include <pcmcia/ds.h>
#include <linux/can.h>
#include <linux/can/dev.h>
#include "sja1000.h"

MODULE_AUTHOR("Stéphane Grosjean <stephane.grosjean@hms-networks.com>");
MODULE_DESCRIPTION("CAN driver for PEAK-System PCAN-PC Cards");
MODULE_LICENSE("GPL v2");

/* PEAK-System PCMCIA driver name */
#define PCC_NAME                "peak_pcmcia"

#define PCC_CHAN_MAX            2

#define PCC_CAN_CLOCK           (16000000 / 2)

#define PCC_MANF_ID             0x0377
#define PCC_CARD_ID             0x0001

#define PCC_CHAN_SIZE           0x20
#define PCC_CHAN_OFF(c)         ((c) * PCC_CHAN_SIZE)
#define PCC_COMN_OFF            (PCC_CHAN_OFF(PCC_CHAN_MAX))
#define PCC_COMN_SIZE           0x40

/* common area registers */
#define PCC_CCR                 0x00
#define PCC_CSR                 0x02
#define PCC_CPR                 0x04
#define PCC_SPI_DIR             0x06
#define PCC_SPI_DOR             0x08
#define PCC_SPI_ADR             0x0a
#define PCC_SPI_IR              0x0c
#define PCC_FW_MAJOR            0x10
#define PCC_FW_MINOR            0x12

/* CCR bits */
#define PCC_CCR_CLK_16          0x00
#define PCC_CCR_CLK_10          0x01
#define PCC_CCR_CLK_21          0x02
#define PCC_CCR_CLK_8           0x03
#define PCC_CCR_CLK_MASK        PCC_CCR_CLK_8

#define PCC_CCR_RST_CHAN(c)     (0x01 << ((c) + 2))
#define PCC_CCR_RST_ALL         (PCC_CCR_RST_CHAN(0) | PCC_CCR_RST_CHAN(1))
#define PCC_CCR_RST_MASK        PCC_CCR_RST_ALL

/* led selection bits */
#define PCC_LED(c)              (1 << (c))
#define PCC_LED_ALL             (PCC_LED(0) | PCC_LED(1))

/* led state value */
#define PCC_LED_ON              0x00
#define PCC_LED_FAST            0x01
#define PCC_LED_SLOW            0x02
#define PCC_LED_OFF             0x03

#define PCC_CCR_LED_CHAN(s, c)  ((s) << (((c) + 2) << 1))

#define PCC_CCR_LED_ON_CHAN(c)          PCC_CCR_LED_CHAN(PCC_LED_ON, c)
#define PCC_CCR_LED_FAST_CHAN(c)        PCC_CCR_LED_CHAN(PCC_LED_FAST, c)
#define PCC_CCR_LED_SLOW_CHAN(c)        PCC_CCR_LED_CHAN(PCC_LED_SLOW, c)
#define PCC_CCR_LED_OFF_CHAN(c)         PCC_CCR_LED_CHAN(PCC_LED_OFF, c)
#define PCC_CCR_LED_MASK_CHAN(c)        PCC_CCR_LED_OFF_CHAN(c)
#define PCC_CCR_LED_OFF_ALL             (PCC_CCR_LED_OFF_CHAN(0) | \
                                         PCC_CCR_LED_OFF_CHAN(1))
#define PCC_CCR_LED_MASK                PCC_CCR_LED_OFF_ALL

#define PCC_CCR_INIT    (PCC_CCR_CLK_16 | PCC_CCR_RST_ALL | PCC_CCR_LED_OFF_ALL)

/* CSR bits */
#define PCC_CSR_SPI_BUSY                0x04

/* time waiting for SPI busy (prevent from infinite loop) */
#define PCC_SPI_MAX_BUSY_WAIT_MS        3

/* max count of reading the SPI status register waiting for a change */
/* (prevent from infinite loop) */
#define PCC_WRITE_MAX_LOOP              1000

/* max nb of int handled by that isr in one shot (prevent from infinite loop) */
#define PCC_ISR_MAX_LOOP                10

/* EEPROM chip instruction set */
/* note: EEPROM Read/Write instructions include A8 bit */
#define PCC_EEP_WRITE(a)        (0x02 | (((a) & 0x100) >> 5))
#define PCC_EEP_READ(a)         (0x03 | (((a) & 0x100) >> 5))
#define PCC_EEP_WRDI            0x04    /* EEPROM Write Disable */
#define PCC_EEP_RDSR            0x05    /* EEPROM Read Status Register */
#define PCC_EEP_WREN            0x06    /* EEPROM Write Enable */

/* EEPROM Status Register bits */
#define PCC_EEP_SR_WEN          0x02    /* EEPROM SR Write Enable bit */
#define PCC_EEP_SR_WIP          0x01    /* EEPROM SR Write In Progress bit */

/*
 * The board configuration is probably following:
 * RX1 is connected to ground.
 * TX1 is not connected.
 * CLKO is not connected.
 * Setting the OCR register to 0xDA is a good idea.
 * This means normal output mode, push-pull and the correct polarity.
 */
#define PCC_OCR                 (OCR_TX0_PUSHPULL | OCR_TX1_PUSHPULL)

/*
 * In the CDR register, you should set CBP to 1.
 * You will probably also want to set the clock divider value to 7
 * (meaning direct oscillator output) because the second SJA1000 chip
 * is driven by the first one CLKOUT output.
 */
#define PCC_CDR                 (CDR_CBP | CDR_CLKOUT_MASK)

struct pcan_channel {
        struct net_device *netdev;
        unsigned long prev_rx_bytes;
        unsigned long prev_tx_bytes;
};

/* PCAN-PC Card private structure */
struct pcan_pccard {
        struct pcmcia_device *pdev;
        int chan_count;
        struct pcan_channel channel[PCC_CHAN_MAX];
        u8 ccr;
        u8 fw_major;
        u8 fw_minor;
        void __iomem *ioport_addr;
        struct timer_list led_timer;
};

static struct pcmcia_device_id pcan_table[] = {
        PCMCIA_DEVICE_MANF_CARD(PCC_MANF_ID, PCC_CARD_ID),
        PCMCIA_DEVICE_NULL,
};

MODULE_DEVICE_TABLE(pcmcia, pcan_table);

static void pcan_set_leds(struct pcan_pccard *card, u8 mask, u8 state);

/*
 * start timer which controls leds state
 */
static void pcan_start_led_timer(struct pcan_pccard *card)
{
        if (!timer_pending(&card->led_timer))
                mod_timer(&card->led_timer, jiffies + HZ);
}

/*
 * stop the timer which controls leds state
 */
static void pcan_stop_led_timer(struct pcan_pccard *card)
{
        timer_delete_sync(&card->led_timer);
}

/*
 * read a sja1000 register
 */
static u8 pcan_read_canreg(const struct sja1000_priv *priv, int port)
{
        return ioread8(priv->reg_base + port);
}

/*
 * write a sja1000 register
 */
static void pcan_write_canreg(const struct sja1000_priv *priv, int port, u8 v)
{
        struct pcan_pccard *card = priv->priv;
        int c = (priv->reg_base - card->ioport_addr) / PCC_CHAN_SIZE;

        /* sja1000 register changes control the leds state */
        if (port == SJA1000_MOD)
                switch (v) {
                case MOD_RM:
                        /* Reset Mode: set led on */
                        pcan_set_leds(card, PCC_LED(c), PCC_LED_ON);
                        break;
                case 0x00:
                        /* Normal Mode: led slow blinking and start led timer */
                        pcan_set_leds(card, PCC_LED(c), PCC_LED_SLOW);
                        pcan_start_led_timer(card);
                        break;
                default:
                        break;
                }

        iowrite8(v, priv->reg_base + port);
}

/*
 * read a register from the common area
 */
static u8 pcan_read_reg(struct pcan_pccard *card, int port)
{
        return ioread8(card->ioport_addr + PCC_COMN_OFF + port);
}

/*
 * write a register into the common area
 */
static void pcan_write_reg(struct pcan_pccard *card, int port, u8 v)
{
        /* cache ccr value */
        if (port == PCC_CCR) {
                if (card->ccr == v)
                        return;
                card->ccr = v;
        }

        iowrite8(v, card->ioport_addr + PCC_COMN_OFF + port);
}

/*
 * check whether the card is present by checking its fw version numbers
 * against values read at probing time.
 */
static inline int pcan_pccard_present(struct pcan_pccard *card)
{
        return ((pcan_read_reg(card, PCC_FW_MAJOR) == card->fw_major) &&
                (pcan_read_reg(card, PCC_FW_MINOR) == card->fw_minor));
}

/*
 * wait for SPI engine while it is busy
 */
static int pcan_wait_spi_busy(struct pcan_pccard *card)
{
        unsigned long timeout = jiffies +
                                msecs_to_jiffies(PCC_SPI_MAX_BUSY_WAIT_MS) + 1;

        /* be sure to read status at least once after sleeping */
        while (pcan_read_reg(card, PCC_CSR) & PCC_CSR_SPI_BUSY) {
                if (time_after(jiffies, timeout))
                        return -EBUSY;
                schedule();
        }

        return 0;
}

/*
 * write data in device eeprom
 */
static int pcan_write_eeprom(struct pcan_pccard *card, u16 addr, u8 v)
{
        u8 status;
        int err, i;

        /* write instruction enabling write */
        pcan_write_reg(card, PCC_SPI_IR, PCC_EEP_WREN);
        err = pcan_wait_spi_busy(card);
        if (err)
                goto we_spi_err;

        /* wait until write enabled */
        for (i = 0; i < PCC_WRITE_MAX_LOOP; i++) {
                /* write instruction reading the status register */
                pcan_write_reg(card, PCC_SPI_IR, PCC_EEP_RDSR);
                err = pcan_wait_spi_busy(card);
                if (err)
                        goto we_spi_err;

                /* get status register value and check write enable bit */
                status = pcan_read_reg(card, PCC_SPI_DIR);
                if (status & PCC_EEP_SR_WEN)
                        break;
        }

        if (i >= PCC_WRITE_MAX_LOOP) {
                dev_err(&card->pdev->dev,
                        "stop waiting to be allowed to write in eeprom\n");
                return -EIO;
        }

        /* set address and data */
        pcan_write_reg(card, PCC_SPI_ADR, addr & 0xff);
        pcan_write_reg(card, PCC_SPI_DOR, v);

        /*
         * write instruction with bit[3] set according to address value:
         * if addr refers to upper half of the memory array: bit[3] = 1
         */
        pcan_write_reg(card, PCC_SPI_IR, PCC_EEP_WRITE(addr));
        err = pcan_wait_spi_busy(card);
        if (err)
                goto we_spi_err;

        /* wait while write in progress */
        for (i = 0; i < PCC_WRITE_MAX_LOOP; i++) {
                /* write instruction reading the status register */
                pcan_write_reg(card, PCC_SPI_IR, PCC_EEP_RDSR);
                err = pcan_wait_spi_busy(card);
                if (err)
                        goto we_spi_err;

                /* get status register value and check write in progress bit */
                status = pcan_read_reg(card, PCC_SPI_DIR);
                if (!(status & PCC_EEP_SR_WIP))
                        break;
        }

        if (i >= PCC_WRITE_MAX_LOOP) {
                dev_err(&card->pdev->dev,
                        "stop waiting for write in eeprom to complete\n");
                return -EIO;
        }

        /* write instruction disabling write */
        pcan_write_reg(card, PCC_SPI_IR, PCC_EEP_WRDI);
        err = pcan_wait_spi_busy(card);
        if (err)
                goto we_spi_err;

        return 0;

we_spi_err:
        dev_err(&card->pdev->dev,
                "stop waiting (spi engine always busy) err %d\n", err);

        return err;
}

static void pcan_set_leds(struct pcan_pccard *card, u8 led_mask, u8 state)
{
        u8 ccr = card->ccr;
        int i;

        for (i = 0; i < card->chan_count; i++)
                if (led_mask & PCC_LED(i)) {
                        /* clear corresponding led bits in ccr */
                        ccr &= ~PCC_CCR_LED_MASK_CHAN(i);
                        /* then set new bits */
                        ccr |= PCC_CCR_LED_CHAN(state, i);
                }

        /* real write only if something has changed in ccr */
        pcan_write_reg(card, PCC_CCR, ccr);
}

/*
 * enable/disable CAN connectors power
 */
static inline void pcan_set_can_power(struct pcan_pccard *card, int onoff)
{
        int err;

        err = pcan_write_eeprom(card, 0, !!onoff);
        if (err)
                dev_err(&card->pdev->dev,
                        "failed setting power %s to can connectors (err %d)\n",
                        (onoff) ? "on" : "off", err);
}

/*
 * set leds state according to channel activity
 */
static void pcan_led_timer(struct timer_list *t)
{
        struct pcan_pccard *card = timer_container_of(card, t, led_timer);
        struct net_device *netdev;
        int i, up_count = 0;
        u8 ccr;

        ccr = card->ccr;
        for (i = 0; i < card->chan_count; i++) {
                /* default is: not configured */
                ccr &= ~PCC_CCR_LED_MASK_CHAN(i);
                ccr |= PCC_CCR_LED_ON_CHAN(i);

                netdev = card->channel[i].netdev;
                if (!netdev || !(netdev->flags & IFF_UP))
                        continue;

                up_count++;

                /* no activity (but configured) */
                ccr &= ~PCC_CCR_LED_MASK_CHAN(i);
                ccr |= PCC_CCR_LED_SLOW_CHAN(i);

                /* if bytes counters changed, set fast blinking led */
                if (netdev->stats.rx_bytes != card->channel[i].prev_rx_bytes) {
                        card->channel[i].prev_rx_bytes = netdev->stats.rx_bytes;
                        ccr &= ~PCC_CCR_LED_MASK_CHAN(i);
                        ccr |= PCC_CCR_LED_FAST_CHAN(i);
                }
                if (netdev->stats.tx_bytes != card->channel[i].prev_tx_bytes) {
                        card->channel[i].prev_tx_bytes = netdev->stats.tx_bytes;
                        ccr &= ~PCC_CCR_LED_MASK_CHAN(i);
                        ccr |= PCC_CCR_LED_FAST_CHAN(i);
                }
        }

        /* write the new leds state */
        pcan_write_reg(card, PCC_CCR, ccr);

        /* restart timer (except if no more configured channels) */
        if (up_count)
                mod_timer(&card->led_timer, jiffies + HZ);
}

/*
 * interrupt service routine
 */
static irqreturn_t pcan_isr(int irq, void *dev_id)
{
        struct pcan_pccard *card = dev_id;
        int irq_handled;

        /* prevent from infinite loop */
        for (irq_handled = 0; irq_handled < PCC_ISR_MAX_LOOP; irq_handled++) {
                /* handle shared interrupt and next loop */
                int nothing_to_handle = 1;
                int i;

                /* check interrupt for each channel */
                for (i = 0; i < card->chan_count; i++) {
                        struct net_device *netdev;

                        /*
                         * check whether the card is present before calling
                         * sja1000_interrupt() to speed up hotplug detection
                         */
                        if (!pcan_pccard_present(card)) {
                                /* card unplugged during isr */
                                return IRQ_NONE;
                        }

                        /*
                         * should check whether all or SJA1000_MAX_IRQ
                         * interrupts have been handled: loop again to be sure.
                         */
                        netdev = card->channel[i].netdev;
                        if (netdev &&
                            sja1000_interrupt(irq, netdev) == IRQ_HANDLED)
                                nothing_to_handle = 0;
                }

                if (nothing_to_handle)
                        break;
        }

        return (irq_handled) ? IRQ_HANDLED : IRQ_NONE;
}

/*
 * free all resources used by the channels and switch off leds and can power
 */
static void pcan_free_channels(struct pcan_pccard *card)
{
        int i;
        u8 led_mask = 0;

        for (i = 0; i < card->chan_count; i++) {
                struct net_device *netdev;
                char name[IFNAMSIZ];

                led_mask |= PCC_LED(i);

                netdev = card->channel[i].netdev;
                if (!netdev)
                        continue;

                strscpy(name, netdev->name, IFNAMSIZ);

                unregister_sja1000dev(netdev);

                free_sja1000dev(netdev);

                dev_info(&card->pdev->dev, "%s removed\n", name);
        }

        /* do it only if device not removed */
        if (pcan_pccard_present(card)) {
                pcan_set_leds(card, led_mask, PCC_LED_OFF);
                pcan_set_can_power(card, 0);
        }
}

/*
 * check if a CAN controller is present at the specified location
 */
static inline int pcan_channel_present(struct sja1000_priv *priv)
{
        /* make sure SJA1000 is in reset mode */
        pcan_write_canreg(priv, SJA1000_MOD, 1);
        pcan_write_canreg(priv, SJA1000_CDR, CDR_PELICAN);

        /* read reset-values */
        if (pcan_read_canreg(priv, SJA1000_CDR) == CDR_PELICAN)
                return 1;

        return 0;
}

static int pcan_add_channels(struct pcan_pccard *card)
{
        struct pcmcia_device *pdev = card->pdev;
        int i, err = 0;
        u8 ccr = PCC_CCR_INIT;

        /* init common registers (reset channels and leds off) */
        card->ccr = ~ccr;
        pcan_write_reg(card, PCC_CCR, ccr);

        /* wait 2ms before unresetting channels */
        usleep_range(2000, 3000);

        ccr &= ~PCC_CCR_RST_ALL;
        pcan_write_reg(card, PCC_CCR, ccr);

        /* create one network device per channel detected */
        for (i = 0; i < ARRAY_SIZE(card->channel); i++) {
                struct net_device *netdev;
                struct sja1000_priv *priv;

                netdev = alloc_sja1000dev(0);
                if (!netdev) {
                        err = -ENOMEM;
                        break;
                }

                /* update linkages */
                priv = netdev_priv(netdev);
                priv->priv = card;
                SET_NETDEV_DEV(netdev, &pdev->dev);
                netdev->dev_id = i;

                priv->irq_flags = IRQF_SHARED;
                netdev->irq = pdev->irq;
                priv->reg_base = card->ioport_addr + PCC_CHAN_OFF(i);

                /* check if channel is present */
                if (!pcan_channel_present(priv)) {
                        dev_err(&pdev->dev, "channel %d not present\n", i);
                        free_sja1000dev(netdev);
                        continue;
                }

                priv->read_reg  = pcan_read_canreg;
                priv->write_reg = pcan_write_canreg;
                priv->can.clock.freq = PCC_CAN_CLOCK;
                priv->ocr = PCC_OCR;
                priv->cdr = PCC_CDR;

                /* Neither a slave device distributes the clock */
                if (i > 0)
                        priv->cdr |= CDR_CLK_OFF;

                priv->flags |= SJA1000_CUSTOM_IRQ_HANDLER;

                /* register SJA1000 device */
                err = register_sja1000dev(netdev);
                if (err) {
                        free_sja1000dev(netdev);
                        continue;
                }

                card->channel[i].netdev = netdev;
                card->chan_count++;

                /* set corresponding led on in the new ccr */
                ccr &= ~PCC_CCR_LED_OFF_CHAN(i);

                dev_info(&pdev->dev,
                        "%s on channel %d at 0x%p irq %d\n",
                        netdev->name, i, priv->reg_base, pdev->irq);
        }

        /* write new ccr (change leds state) */
        pcan_write_reg(card, PCC_CCR, ccr);

        return err;
}

static int pcan_conf_check(struct pcmcia_device *pdev, void *priv_data)
{
        pdev->resource[0]->flags &= ~IO_DATA_PATH_WIDTH;
        pdev->resource[0]->flags |= IO_DATA_PATH_WIDTH_8; /* only */
        pdev->io_lines = 10;

        /* This reserves IO space but doesn't actually enable it */
        return pcmcia_request_io(pdev);
}

/*
 * free all resources used by the device
 */
static void pcan_free(struct pcmcia_device *pdev)
{
        struct pcan_pccard *card = pdev->priv;

        if (!card)
                return;

        free_irq(pdev->irq, card);
        pcan_stop_led_timer(card);

        pcan_free_channels(card);

        ioport_unmap(card->ioport_addr);

        kfree(card);
        pdev->priv = NULL;
}

/*
 * setup PCMCIA socket and probe for PEAK-System PC-CARD
 */
static int pcan_probe(struct pcmcia_device *pdev)
{
        struct pcan_pccard *card;
        int err;

        pdev->config_flags |= CONF_ENABLE_IRQ | CONF_AUTO_SET_IO;

        err = pcmcia_loop_config(pdev, pcan_conf_check, NULL);
        if (err) {
                dev_err(&pdev->dev, "pcmcia_loop_config() error %d\n", err);
                goto probe_err_1;
        }

        if (!pdev->irq) {
                dev_err(&pdev->dev, "no irq assigned\n");
                err = -ENODEV;
                goto probe_err_1;
        }

        err = pcmcia_enable_device(pdev);
        if (err) {
                dev_err(&pdev->dev, "pcmcia_enable_device failed err=%d\n",
                        err);
                goto probe_err_1;
        }

        card = kzalloc_obj(struct pcan_pccard);
        if (!card) {
                err = -ENOMEM;
                goto probe_err_2;
        }

        card->pdev = pdev;
        pdev->priv = card;

        /* sja1000 api uses iomem */
        card->ioport_addr = ioport_map(pdev->resource[0]->start,
                                        resource_size(pdev->resource[0]));
        if (!card->ioport_addr) {
                dev_err(&pdev->dev, "couldn't map io port into io memory\n");
                err = -ENOMEM;
                goto probe_err_3;
        }
        card->fw_major = pcan_read_reg(card, PCC_FW_MAJOR);
        card->fw_minor = pcan_read_reg(card, PCC_FW_MINOR);

        /* display board name and firmware version */
        dev_info(&pdev->dev, "PEAK-System pcmcia card %s fw %d.%d\n",
                pdev->prod_id[1] ? pdev->prod_id[1] : "PCAN-PC Card",
                card->fw_major, card->fw_minor);

        /* detect available channels */
        pcan_add_channels(card);
        if (!card->chan_count) {
                err = -ENOMEM;
                goto probe_err_4;
        }

        /* init the timer which controls the leds */
        timer_setup(&card->led_timer, pcan_led_timer, 0);

        /* request the given irq */
        err = request_irq(pdev->irq, &pcan_isr, IRQF_SHARED, PCC_NAME, card);
        if (err) {
                dev_err(&pdev->dev, "couldn't request irq%d\n", pdev->irq);
                goto probe_err_5;
        }

        /* power on the connectors */
        pcan_set_can_power(card, 1);

        return 0;

probe_err_5:
        /* unregister can devices from network */
        pcan_free_channels(card);

probe_err_4:
        ioport_unmap(card->ioport_addr);

probe_err_3:
        kfree(card);
        pdev->priv = NULL;

probe_err_2:
        pcmcia_disable_device(pdev);

probe_err_1:
        return err;
}

/*
 * release claimed resources
 */
static void pcan_remove(struct pcmcia_device *pdev)
{
        pcan_free(pdev);
        pcmcia_disable_device(pdev);
}

static struct pcmcia_driver pcan_driver = {
        .name = PCC_NAME,
        .probe = pcan_probe,
        .remove = pcan_remove,
        .id_table = pcan_table,
};
module_pcmcia_driver(pcan_driver);