// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (C) 2005 Marc Kleine-Budde, Pengutronix
 * Copyright (C) 2006 Andrey Volkov, Varma Electronics
 * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/workqueue.h>
#include <linux/can.h>
#include <linux/can/can-ml.h>
#include <linux/can/dev.h>
#include <linux/can/skb.h>
#include <linux/can/led.h>
#include <linux/gpio/consumer.h>
#include <linux/of.h>

#define MOD_DESC "CAN device driver interface"

MODULE_DESCRIPTION(MOD_DESC);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Wolfgang Grandegger <wg@grandegger.com>");

static void can_update_state_error_stats(struct net_device *dev,
                                         enum can_state new_state)
{
        struct can_priv *priv = netdev_priv(dev);

        if (new_state <= priv->state)
                return;

        switch (new_state) {
        case CAN_STATE_ERROR_WARNING:
                priv->can_stats.error_warning++;
                break;
        case CAN_STATE_ERROR_PASSIVE:
                priv->can_stats.error_passive++;
                break;
        case CAN_STATE_BUS_OFF:
                priv->can_stats.bus_off++;
                break;
        default:
                break;
        }
}

static int can_tx_state_to_frame(struct net_device *dev, enum can_state state)
{
        switch (state) {
        case CAN_STATE_ERROR_ACTIVE:
                return CAN_ERR_CRTL_ACTIVE;
        case CAN_STATE_ERROR_WARNING:
                return CAN_ERR_CRTL_TX_WARNING;
        case CAN_STATE_ERROR_PASSIVE:
                return CAN_ERR_CRTL_TX_PASSIVE;
        default:
                return 0;
        }
}

static int can_rx_state_to_frame(struct net_device *dev, enum can_state state)
{
        switch (state) {
        case CAN_STATE_ERROR_ACTIVE:
                return CAN_ERR_CRTL_ACTIVE;
        case CAN_STATE_ERROR_WARNING:
                return CAN_ERR_CRTL_RX_WARNING;
        case CAN_STATE_ERROR_PASSIVE:
                return CAN_ERR_CRTL_RX_PASSIVE;
        default:
                return 0;
        }
}

const char *can_get_state_str(const enum can_state state)
{
        switch (state) {
        case CAN_STATE_ERROR_ACTIVE:
                return "Error Active";
        case CAN_STATE_ERROR_WARNING:
                return "Error Warning";
        case CAN_STATE_ERROR_PASSIVE:
                return "Error Passive";
        case CAN_STATE_BUS_OFF:
                return "Bus Off";
        case CAN_STATE_STOPPED:
                return "Stopped";
        case CAN_STATE_SLEEPING:
                return "Sleeping";
        default:
                return "<unknown>";
        }

        return "<unknown>";
}
EXPORT_SYMBOL_GPL(can_get_state_str);

void can_change_state(struct net_device *dev, struct can_frame *cf,
                      enum can_state tx_state, enum can_state rx_state)
{
        struct can_priv *priv = netdev_priv(dev);
        enum can_state new_state = max(tx_state, rx_state);

        if (unlikely(new_state == priv->state)) {
                netdev_warn(dev, "%s: oops, state did not change", __func__);
                return;
        }

        netdev_dbg(dev, "Controller changed from %s State (%d) into %s State (%d).\n",
                   can_get_state_str(priv->state), priv->state,
                   can_get_state_str(new_state), new_state);

        can_update_state_error_stats(dev, new_state);
        priv->state = new_state;

        if (!cf)
                return;

        if (unlikely(new_state == CAN_STATE_BUS_OFF)) {
                cf->can_id |= CAN_ERR_BUSOFF;
                return;
        }

        cf->can_id |= CAN_ERR_CRTL;
        cf->data[1] |= tx_state >= rx_state ?
                       can_tx_state_to_frame(dev, tx_state) : 0;
        cf->data[1] |= tx_state <= rx_state ?
                       can_rx_state_to_frame(dev, rx_state) : 0;
}
EXPORT_SYMBOL_GPL(can_change_state);

/* CAN device restart for bus-off recovery */
static void can_restart(struct net_device *dev)
{
        struct can_priv *priv = netdev_priv(dev);
        struct net_device_stats *stats = &dev->stats;
        struct sk_buff *skb;
        struct can_frame *cf;
        int err;

        BUG_ON(netif_carrier_ok(dev));

        /* No synchronization needed because the device is bus-off and
         * no messages can come in or go out.
         */
        can_flush_echo_skb(dev);

        /* send restart message upstream */
        skb = alloc_can_err_skb(dev, &cf);
        if (!skb)
                goto restart;

        cf->can_id |= CAN_ERR_RESTARTED;

        stats->rx_packets++;
        stats->rx_bytes += cf->len;

        netif_rx_ni(skb);

restart:
        netdev_dbg(dev, "restarted\n");
        priv->can_stats.restarts++;

        /* Now restart the device */
        err = priv->do_set_mode(dev, CAN_MODE_START);

        netif_carrier_on(dev);
        if (err)
                netdev_err(dev, "Error %d during restart", err);
}

static void can_restart_work(struct work_struct *work)
{
        struct delayed_work *dwork = to_delayed_work(work);
        struct can_priv *priv = container_of(dwork, struct can_priv,
                                             restart_work);

        can_restart(priv->dev);
}

int can_restart_now(struct net_device *dev)
{
        struct can_priv *priv = netdev_priv(dev);

        /* A manual restart is only permitted if automatic restart is
         * disabled and the device is in the bus-off state
         */
        if (priv->restart_ms)
                return -EINVAL;
        if (priv->state != CAN_STATE_BUS_OFF)
                return -EBUSY;

        cancel_delayed_work_sync(&priv->restart_work);
        can_restart(dev);

        return 0;
}

/* CAN bus-off
 *
 * This functions should be called when the device goes bus-off to
 * tell the netif layer that no more packets can be sent or received.
 * If enabled, a timer is started to trigger bus-off recovery.
 */
void can_bus_off(struct net_device *dev)
{
        struct can_priv *priv = netdev_priv(dev);

        if (priv->restart_ms)
                netdev_info(dev, "bus-off, scheduling restart in %d ms\n",
                            priv->restart_ms);
        else
                netdev_info(dev, "bus-off\n");

        netif_carrier_off(dev);

        if (priv->restart_ms)
                schedule_delayed_work(&priv->restart_work,
                                      msecs_to_jiffies(priv->restart_ms));
}
EXPORT_SYMBOL_GPL(can_bus_off);

void can_setup(struct net_device *dev)
{
        dev->type = ARPHRD_CAN;
        dev->mtu = CAN_MTU;
        dev->hard_header_len = 0;
        dev->addr_len = 0;
        dev->tx_queue_len = 10;

        /* New-style flags. */
        dev->flags = IFF_NOARP;
        dev->features = NETIF_F_HW_CSUM;
}

/* Allocate and setup space for the CAN network device */
struct net_device *alloc_candev_mqs(int sizeof_priv, unsigned int echo_skb_max,
                                    unsigned int txqs, unsigned int rxqs)
{
        struct can_ml_priv *can_ml;
        struct net_device *dev;
        struct can_priv *priv;
        int size;

        /* We put the driver's priv, the CAN mid layer priv and the
         * echo skb into the netdevice's priv. The memory layout for
         * the netdev_priv is like this:
         *
         * +-------------------------+
         * | driver's priv           |
         * +-------------------------+
         * | struct can_ml_priv      |
         * +-------------------------+
         * | array of struct sk_buff |
         * +-------------------------+
         */

        size = ALIGN(sizeof_priv, NETDEV_ALIGN) + sizeof(struct can_ml_priv);

        if (echo_skb_max)
                size = ALIGN(size, sizeof(struct sk_buff *)) +
                        echo_skb_max * sizeof(struct sk_buff *);

        dev = alloc_netdev_mqs(size, "can%d", NET_NAME_UNKNOWN, can_setup,
                               txqs, rxqs);
        if (!dev)
                return NULL;

        priv = netdev_priv(dev);
        priv->dev = dev;

        can_ml = (void *)priv + ALIGN(sizeof_priv, NETDEV_ALIGN);
        can_set_ml_priv(dev, can_ml);

        if (echo_skb_max) {
                priv->echo_skb_max = echo_skb_max;
                priv->echo_skb = (void *)priv +
                        (size - echo_skb_max * sizeof(struct sk_buff *));
        }

        priv->state = CAN_STATE_STOPPED;

        INIT_DELAYED_WORK(&priv->restart_work, can_restart_work);

        return dev;
}
EXPORT_SYMBOL_GPL(alloc_candev_mqs);

/* Free space of the CAN network device */
void free_candev(struct net_device *dev)
{
        free_netdev(dev);
}
EXPORT_SYMBOL_GPL(free_candev);

/* changing MTU and control mode for CAN/CANFD devices */
int can_change_mtu(struct net_device *dev, int new_mtu)
{
        struct can_priv *priv = netdev_priv(dev);

        /* Do not allow changing the MTU while running */
        if (dev->flags & IFF_UP)
                return -EBUSY;

        /* allow change of MTU according to the CANFD ability of the device */
        switch (new_mtu) {
        case CAN_MTU:
                /* 'CANFD-only' controllers can not switch to CAN_MTU */
                if (priv->ctrlmode_static & CAN_CTRLMODE_FD)
                        return -EINVAL;

                priv->ctrlmode &= ~CAN_CTRLMODE_FD;
                break;

        case CANFD_MTU:
                /* check for potential CANFD ability */
                if (!(priv->ctrlmode_supported & CAN_CTRLMODE_FD) &&
                    !(priv->ctrlmode_static & CAN_CTRLMODE_FD))
                        return -EINVAL;

                priv->ctrlmode |= CAN_CTRLMODE_FD;
                break;

        default:
                return -EINVAL;
        }

        dev->mtu = new_mtu;
        return 0;
}
EXPORT_SYMBOL_GPL(can_change_mtu);

/* Common open function when the device gets opened.
 *
 * This function should be called in the open function of the device
 * driver.
 */
int open_candev(struct net_device *dev)
{
        struct can_priv *priv = netdev_priv(dev);

        if (!priv->bittiming.bitrate) {
                netdev_err(dev, "bit-timing not yet defined\n");
                return -EINVAL;
        }

        /* For CAN FD the data bitrate has to be >= the arbitration bitrate */
        if ((priv->ctrlmode & CAN_CTRLMODE_FD) &&
            (!priv->data_bittiming.bitrate ||
             priv->data_bittiming.bitrate < priv->bittiming.bitrate)) {
                netdev_err(dev, "incorrect/missing data bit-timing\n");
                return -EINVAL;
        }

        /* Switch carrier on if device was stopped while in bus-off state */
        if (!netif_carrier_ok(dev))
                netif_carrier_on(dev);

        return 0;
}
EXPORT_SYMBOL_GPL(open_candev);

#ifdef CONFIG_OF
/* Common function that can be used to understand the limitation of
 * a transceiver when it provides no means to determine these limitations
 * at runtime.
 */
void of_can_transceiver(struct net_device *dev)
{
        struct device_node *dn;
        struct can_priv *priv = netdev_priv(dev);
        struct device_node *np = dev->dev.parent->of_node;
        int ret;

        dn = of_get_child_by_name(np, "can-transceiver");
        if (!dn)
                return;

        ret = of_property_read_u32(dn, "max-bitrate", &priv->bitrate_max);
        of_node_put(dn);
        if ((ret && ret != -EINVAL) || (!ret && !priv->bitrate_max))
                netdev_warn(dev, "Invalid value for transceiver max bitrate. Ignoring bitrate limit.\n");
}
EXPORT_SYMBOL_GPL(of_can_transceiver);
#endif

/* Common close function for cleanup before the device gets closed.
 *
 * This function should be called in the close function of the device
 * driver.
 */
void close_candev(struct net_device *dev)
{
        struct can_priv *priv = netdev_priv(dev);

        cancel_delayed_work_sync(&priv->restart_work);
        can_flush_echo_skb(dev);
}
EXPORT_SYMBOL_GPL(close_candev);

static int can_set_termination(struct net_device *ndev, u16 term)
{
        struct can_priv *priv = netdev_priv(ndev);
        int set;

        if (term == priv->termination_gpio_ohms[CAN_TERMINATION_GPIO_ENABLED])
                set = 1;
        else
                set = 0;

        gpiod_set_value(priv->termination_gpio, set);

        return 0;
}

static int can_get_termination(struct net_device *ndev)
{
        struct can_priv *priv = netdev_priv(ndev);
        struct device *dev = ndev->dev.parent;
        struct gpio_desc *gpio;
        u32 term;
        int ret;

        /* Disabling termination by default is the safe choice: Else if many
         * bus participants enable it, no communication is possible at all.
         */
        gpio = devm_gpiod_get_optional(dev, "termination", GPIOD_OUT_LOW);
        if (IS_ERR(gpio))
                return dev_err_probe(dev, PTR_ERR(gpio),
                                     "Cannot get termination-gpios\n");

        if (!gpio)
                return 0;

        ret = device_property_read_u32(dev, "termination-ohms", &term);
        if (ret) {
                netdev_err(ndev, "Cannot get termination-ohms: %pe\n",
                           ERR_PTR(ret));
                return ret;
        }

        if (term > U16_MAX) {
                netdev_err(ndev, "Invalid termination-ohms value (%u > %u)\n",
                           term, U16_MAX);
                return -EINVAL;
        }

        priv->termination_const_cnt = ARRAY_SIZE(priv->termination_gpio_ohms);
        priv->termination_const = priv->termination_gpio_ohms;
        priv->termination_gpio = gpio;
        priv->termination_gpio_ohms[CAN_TERMINATION_GPIO_DISABLED] =
                CAN_TERMINATION_DISABLED;
        priv->termination_gpio_ohms[CAN_TERMINATION_GPIO_ENABLED] = term;
        priv->do_set_termination = can_set_termination;

        return 0;
}

/* Register the CAN network device */
int register_candev(struct net_device *dev)
{
        struct can_priv *priv = netdev_priv(dev);
        int err;

        /* Ensure termination_const, termination_const_cnt and
         * do_set_termination consistency. All must be either set or
         * unset.
         */
        if ((!priv->termination_const != !priv->termination_const_cnt) ||
            (!priv->termination_const != !priv->do_set_termination))
                return -EINVAL;

        if (!priv->bitrate_const != !priv->bitrate_const_cnt)
                return -EINVAL;

        if (!priv->data_bitrate_const != !priv->data_bitrate_const_cnt)
                return -EINVAL;

        if (!priv->termination_const) {
                err = can_get_termination(dev);
                if (err)
                        return err;
        }

        dev->rtnl_link_ops = &can_link_ops;
        netif_carrier_off(dev);

        return register_netdev(dev);
}
EXPORT_SYMBOL_GPL(register_candev);

/* Unregister the CAN network device */
void unregister_candev(struct net_device *dev)
{
        unregister_netdev(dev);
}
EXPORT_SYMBOL_GPL(unregister_candev);

/* Test if a network device is a candev based device
 * and return the can_priv* if so.
 */
struct can_priv *safe_candev_priv(struct net_device *dev)
{
        if (dev->type != ARPHRD_CAN || dev->rtnl_link_ops != &can_link_ops)
                return NULL;

        return netdev_priv(dev);
}
EXPORT_SYMBOL_GPL(safe_candev_priv);

static __init int can_dev_init(void)
{
        int err;

        can_led_notifier_init();

        err = can_netlink_register();
        if (!err)
                pr_info(MOD_DESC "\n");

        return err;
}
module_init(can_dev_init);

static __exit void can_dev_exit(void)
{
        can_netlink_unregister();

        can_led_notifier_exit();
}
module_exit(can_dev_exit);

MODULE_ALIAS_RTNL_LINK("can");