ARM: mm: Recreate kernel mappings in early_paging_init()

[linux/fpc-iii.git] / drivers / net / can / flexcan.c

/*
 * flexcan.c - FLEXCAN CAN controller driver
 *
 * Copyright (c) 2005-2006 Varma Electronics Oy
 * Copyright (c) 2009 Sascha Hauer, Pengutronix
 * Copyright (c) 2010 Marc Kleine-Budde, Pengutronix
 *
 * Based on code originally by Andrey Volkov <avolkov@varma-el.com>
 *
 * LICENCE:
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation version 2.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

#include <linux/netdevice.h>
#include <linux/can.h>
#include <linux/can/dev.h>
#include <linux/can/error.h>
#include <linux/can/led.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>

#define DRV_NAME                        "flexcan"

/* 8 for RX fifo and 2 error handling */
#define FLEXCAN_NAPI_WEIGHT             (8 + 2)

/* FLEXCAN module configuration register (CANMCR) bits */
#define FLEXCAN_MCR_MDIS                BIT(31)
#define FLEXCAN_MCR_FRZ                 BIT(30)
#define FLEXCAN_MCR_FEN                 BIT(29)
#define FLEXCAN_MCR_HALT                BIT(28)
#define FLEXCAN_MCR_NOT_RDY             BIT(27)
#define FLEXCAN_MCR_WAK_MSK             BIT(26)
#define FLEXCAN_MCR_SOFTRST             BIT(25)
#define FLEXCAN_MCR_FRZ_ACK             BIT(24)
#define FLEXCAN_MCR_SUPV                BIT(23)
#define FLEXCAN_MCR_SLF_WAK             BIT(22)
#define FLEXCAN_MCR_WRN_EN              BIT(21)
#define FLEXCAN_MCR_LPM_ACK             BIT(20)
#define FLEXCAN_MCR_WAK_SRC             BIT(19)
#define FLEXCAN_MCR_DOZE                BIT(18)
#define FLEXCAN_MCR_SRX_DIS             BIT(17)
#define FLEXCAN_MCR_BCC                 BIT(16)
#define FLEXCAN_MCR_LPRIO_EN            BIT(13)
#define FLEXCAN_MCR_AEN                 BIT(12)
#define FLEXCAN_MCR_MAXMB(x)            ((x) & 0xf)
#define FLEXCAN_MCR_IDAM_A              (0 << 8)
#define FLEXCAN_MCR_IDAM_B              (1 << 8)
#define FLEXCAN_MCR_IDAM_C              (2 << 8)
#define FLEXCAN_MCR_IDAM_D              (3 << 8)

/* FLEXCAN control register (CANCTRL) bits */
#define FLEXCAN_CTRL_PRESDIV(x)         (((x) & 0xff) << 24)
#define FLEXCAN_CTRL_RJW(x)             (((x) & 0x03) << 22)
#define FLEXCAN_CTRL_PSEG1(x)           (((x) & 0x07) << 19)
#define FLEXCAN_CTRL_PSEG2(x)           (((x) & 0x07) << 16)
#define FLEXCAN_CTRL_BOFF_MSK           BIT(15)
#define FLEXCAN_CTRL_ERR_MSK            BIT(14)
#define FLEXCAN_CTRL_CLK_SRC            BIT(13)
#define FLEXCAN_CTRL_LPB                BIT(12)
#define FLEXCAN_CTRL_TWRN_MSK           BIT(11)
#define FLEXCAN_CTRL_RWRN_MSK           BIT(10)
#define FLEXCAN_CTRL_SMP                BIT(7)
#define FLEXCAN_CTRL_BOFF_REC           BIT(6)
#define FLEXCAN_CTRL_TSYN               BIT(5)
#define FLEXCAN_CTRL_LBUF               BIT(4)
#define FLEXCAN_CTRL_LOM                BIT(3)
#define FLEXCAN_CTRL_PROPSEG(x)         ((x) & 0x07)
#define FLEXCAN_CTRL_ERR_BUS            (FLEXCAN_CTRL_ERR_MSK)
#define FLEXCAN_CTRL_ERR_STATE \
        (FLEXCAN_CTRL_TWRN_MSK | FLEXCAN_CTRL_RWRN_MSK | \
         FLEXCAN_CTRL_BOFF_MSK)
#define FLEXCAN_CTRL_ERR_ALL \
        (FLEXCAN_CTRL_ERR_BUS | FLEXCAN_CTRL_ERR_STATE)

/* FLEXCAN error and status register (ESR) bits */
#define FLEXCAN_ESR_TWRN_INT            BIT(17)
#define FLEXCAN_ESR_RWRN_INT            BIT(16)
#define FLEXCAN_ESR_BIT1_ERR            BIT(15)
#define FLEXCAN_ESR_BIT0_ERR            BIT(14)
#define FLEXCAN_ESR_ACK_ERR             BIT(13)
#define FLEXCAN_ESR_CRC_ERR             BIT(12)
#define FLEXCAN_ESR_FRM_ERR             BIT(11)
#define FLEXCAN_ESR_STF_ERR             BIT(10)
#define FLEXCAN_ESR_TX_WRN              BIT(9)
#define FLEXCAN_ESR_RX_WRN              BIT(8)
#define FLEXCAN_ESR_IDLE                BIT(7)
#define FLEXCAN_ESR_TXRX                BIT(6)
#define FLEXCAN_EST_FLT_CONF_SHIFT      (4)
#define FLEXCAN_ESR_FLT_CONF_MASK       (0x3 << FLEXCAN_EST_FLT_CONF_SHIFT)
#define FLEXCAN_ESR_FLT_CONF_ACTIVE     (0x0 << FLEXCAN_EST_FLT_CONF_SHIFT)
#define FLEXCAN_ESR_FLT_CONF_PASSIVE    (0x1 << FLEXCAN_EST_FLT_CONF_SHIFT)
#define FLEXCAN_ESR_BOFF_INT            BIT(2)
#define FLEXCAN_ESR_ERR_INT             BIT(1)
#define FLEXCAN_ESR_WAK_INT             BIT(0)
#define FLEXCAN_ESR_ERR_BUS \
        (FLEXCAN_ESR_BIT1_ERR | FLEXCAN_ESR_BIT0_ERR | \
         FLEXCAN_ESR_ACK_ERR | FLEXCAN_ESR_CRC_ERR | \
         FLEXCAN_ESR_FRM_ERR | FLEXCAN_ESR_STF_ERR)
#define FLEXCAN_ESR_ERR_STATE \
        (FLEXCAN_ESR_TWRN_INT | FLEXCAN_ESR_RWRN_INT | FLEXCAN_ESR_BOFF_INT)
#define FLEXCAN_ESR_ERR_ALL \
        (FLEXCAN_ESR_ERR_BUS | FLEXCAN_ESR_ERR_STATE)
#define FLEXCAN_ESR_ALL_INT \
        (FLEXCAN_ESR_TWRN_INT | FLEXCAN_ESR_RWRN_INT | \
         FLEXCAN_ESR_BOFF_INT | FLEXCAN_ESR_ERR_INT)

/* FLEXCAN interrupt flag register (IFLAG) bits */
#define FLEXCAN_TX_BUF_ID               8
#define FLEXCAN_IFLAG_BUF(x)            BIT(x)
#define FLEXCAN_IFLAG_RX_FIFO_OVERFLOW  BIT(7)
#define FLEXCAN_IFLAG_RX_FIFO_WARN      BIT(6)
#define FLEXCAN_IFLAG_RX_FIFO_AVAILABLE BIT(5)
#define FLEXCAN_IFLAG_DEFAULT \
        (FLEXCAN_IFLAG_RX_FIFO_OVERFLOW | FLEXCAN_IFLAG_RX_FIFO_AVAILABLE | \
         FLEXCAN_IFLAG_BUF(FLEXCAN_TX_BUF_ID))

/* FLEXCAN message buffers */
#define FLEXCAN_MB_CNT_CODE(x)          (((x) & 0xf) << 24)
#define FLEXCAN_MB_CNT_SRR              BIT(22)
#define FLEXCAN_MB_CNT_IDE              BIT(21)
#define FLEXCAN_MB_CNT_RTR              BIT(20)
#define FLEXCAN_MB_CNT_LENGTH(x)        (((x) & 0xf) << 16)
#define FLEXCAN_MB_CNT_TIMESTAMP(x)     ((x) & 0xffff)

#define FLEXCAN_MB_CODE_MASK            (0xf0ffffff)

/*
 * FLEXCAN hardware feature flags
 *
 * Below is some version info we got:
 *    SOC   Version   IP-Version  Glitch-  [TR]WRN_INT
 *                                Filter?   connected?
 *   MX25  FlexCAN2  03.00.00.00     no         no
 *   MX28  FlexCAN2  03.00.04.00    yes        yes
 *   MX35  FlexCAN2  03.00.00.00     no         no
 *   MX53  FlexCAN2  03.00.00.00    yes         no
 *   MX6s  FlexCAN3  10.00.12.00    yes        yes
 *
 * Some SOCs do not have the RX_WARN & TX_WARN interrupt line connected.
 */
#define FLEXCAN_HAS_V10_FEATURES        BIT(1) /* For core version >= 10 */
#define FLEXCAN_HAS_BROKEN_ERR_STATE    BIT(2) /* [TR]WRN_INT not connected */

/* Structure of the message buffer */
struct flexcan_mb {
        u32 can_ctrl;
        u32 can_id;
        u32 data[2];
};

/* Structure of the hardware registers */
struct flexcan_regs {
        u32 mcr;                /* 0x00 */
        u32 ctrl;               /* 0x04 */
        u32 timer;              /* 0x08 */
        u32 _reserved1;         /* 0x0c */
        u32 rxgmask;            /* 0x10 */
        u32 rx14mask;           /* 0x14 */
        u32 rx15mask;           /* 0x18 */
        u32 ecr;                /* 0x1c */
        u32 esr;                /* 0x20 */
        u32 imask2;             /* 0x24 */
        u32 imask1;             /* 0x28 */
        u32 iflag2;             /* 0x2c */
        u32 iflag1;             /* 0x30 */
        u32 crl2;               /* 0x34 */
        u32 esr2;               /* 0x38 */
        u32 imeur;              /* 0x3c */
        u32 lrfr;               /* 0x40 */
        u32 crcr;               /* 0x44 */
        u32 rxfgmask;           /* 0x48 */
        u32 rxfir;              /* 0x4c */
        u32 _reserved3[12];
        struct flexcan_mb cantxfg[64];
};

struct flexcan_devtype_data {
        u32 features;   /* hardware controller features */
};

struct flexcan_priv {
        struct can_priv can;
        struct net_device *dev;
        struct napi_struct napi;

        void __iomem *base;
        u32 reg_esr;
        u32 reg_ctrl_default;

        struct clk *clk_ipg;
        struct clk *clk_per;
        struct flexcan_platform_data *pdata;
        const struct flexcan_devtype_data *devtype_data;
        struct regulator *reg_xceiver;
};

static struct flexcan_devtype_data fsl_p1010_devtype_data = {
        .features = FLEXCAN_HAS_BROKEN_ERR_STATE,
};
static struct flexcan_devtype_data fsl_imx28_devtype_data;
static struct flexcan_devtype_data fsl_imx6q_devtype_data = {
        .features = FLEXCAN_HAS_V10_FEATURES,
};

static const struct can_bittiming_const flexcan_bittiming_const = {
        .name = DRV_NAME,
        .tseg1_min = 4,
        .tseg1_max = 16,
        .tseg2_min = 2,
        .tseg2_max = 8,
        .sjw_max = 4,
        .brp_min = 1,
        .brp_max = 256,
        .brp_inc = 1,
};

/*
 * Abstract off the read/write for arm versus ppc.
 */
#if defined(__BIG_ENDIAN)
static inline u32 flexcan_read(void __iomem *addr)
{
        return in_be32(addr);
}

static inline void flexcan_write(u32 val, void __iomem *addr)
{
        out_be32(addr, val);
}
#else
static inline u32 flexcan_read(void __iomem *addr)
{
        return readl(addr);
}

static inline void flexcan_write(u32 val, void __iomem *addr)
{
        writel(val, addr);
}
#endif

static inline int flexcan_has_and_handle_berr(const struct flexcan_priv *priv,
                                              u32 reg_esr)
{
        return (priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING) &&
                (reg_esr & FLEXCAN_ESR_ERR_BUS);
}

static inline void flexcan_chip_enable(struct flexcan_priv *priv)
{
        struct flexcan_regs __iomem *regs = priv->base;
        u32 reg;

        reg = flexcan_read(&regs->mcr);
        reg &= ~FLEXCAN_MCR_MDIS;
        flexcan_write(reg, &regs->mcr);

        udelay(10);
}

static inline void flexcan_chip_disable(struct flexcan_priv *priv)
{
        struct flexcan_regs __iomem *regs = priv->base;
        u32 reg;

        reg = flexcan_read(&regs->mcr);
        reg |= FLEXCAN_MCR_MDIS;
        flexcan_write(reg, &regs->mcr);
}

static int flexcan_get_berr_counter(const struct net_device *dev,
                                    struct can_berr_counter *bec)
{
        const struct flexcan_priv *priv = netdev_priv(dev);
        struct flexcan_regs __iomem *regs = priv->base;
        u32 reg = flexcan_read(&regs->ecr);

        bec->txerr = (reg >> 0) & 0xff;
        bec->rxerr = (reg >> 8) & 0xff;

        return 0;
}

static int flexcan_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        const struct flexcan_priv *priv = netdev_priv(dev);
        struct flexcan_regs __iomem *regs = priv->base;
        struct can_frame *cf = (struct can_frame *)skb->data;
        u32 can_id;
        u32 ctrl = FLEXCAN_MB_CNT_CODE(0xc) | (cf->can_dlc << 16);

        if (can_dropped_invalid_skb(dev, skb))
                return NETDEV_TX_OK;

        netif_stop_queue(dev);

        if (cf->can_id & CAN_EFF_FLAG) {
                can_id = cf->can_id & CAN_EFF_MASK;
                ctrl |= FLEXCAN_MB_CNT_IDE | FLEXCAN_MB_CNT_SRR;
        } else {
                can_id = (cf->can_id & CAN_SFF_MASK) << 18;
        }

        if (cf->can_id & CAN_RTR_FLAG)
                ctrl |= FLEXCAN_MB_CNT_RTR;

        if (cf->can_dlc > 0) {
                u32 data = be32_to_cpup((__be32 *)&cf->data[0]);
                flexcan_write(data, &regs->cantxfg[FLEXCAN_TX_BUF_ID].data[0]);
        }
        if (cf->can_dlc > 3) {
                u32 data = be32_to_cpup((__be32 *)&cf->data[4]);
                flexcan_write(data, &regs->cantxfg[FLEXCAN_TX_BUF_ID].data[1]);
        }

        can_put_echo_skb(skb, dev, 0);

        flexcan_write(can_id, &regs->cantxfg[FLEXCAN_TX_BUF_ID].can_id);
        flexcan_write(ctrl, &regs->cantxfg[FLEXCAN_TX_BUF_ID].can_ctrl);

        return NETDEV_TX_OK;
}

static void do_bus_err(struct net_device *dev,
                       struct can_frame *cf, u32 reg_esr)
{
        struct flexcan_priv *priv = netdev_priv(dev);
        int rx_errors = 0, tx_errors = 0;

        cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;

        if (reg_esr & FLEXCAN_ESR_BIT1_ERR) {
                netdev_dbg(dev, "BIT1_ERR irq\n");
                cf->data[2] |= CAN_ERR_PROT_BIT1;
                tx_errors = 1;
        }
        if (reg_esr & FLEXCAN_ESR_BIT0_ERR) {
                netdev_dbg(dev, "BIT0_ERR irq\n");
                cf->data[2] |= CAN_ERR_PROT_BIT0;
                tx_errors = 1;
        }
        if (reg_esr & FLEXCAN_ESR_ACK_ERR) {
                netdev_dbg(dev, "ACK_ERR irq\n");
                cf->can_id |= CAN_ERR_ACK;
                cf->data[3] |= CAN_ERR_PROT_LOC_ACK;
                tx_errors = 1;
        }
        if (reg_esr & FLEXCAN_ESR_CRC_ERR) {
                netdev_dbg(dev, "CRC_ERR irq\n");
                cf->data[2] |= CAN_ERR_PROT_BIT;
                cf->data[3] |= CAN_ERR_PROT_LOC_CRC_SEQ;
                rx_errors = 1;
        }
        if (reg_esr & FLEXCAN_ESR_FRM_ERR) {
                netdev_dbg(dev, "FRM_ERR irq\n");
                cf->data[2] |= CAN_ERR_PROT_FORM;
                rx_errors = 1;
        }
        if (reg_esr & FLEXCAN_ESR_STF_ERR) {
                netdev_dbg(dev, "STF_ERR irq\n");
                cf->data[2] |= CAN_ERR_PROT_STUFF;
                rx_errors = 1;
        }

        priv->can.can_stats.bus_error++;
        if (rx_errors)
                dev->stats.rx_errors++;
        if (tx_errors)
                dev->stats.tx_errors++;
}

static int flexcan_poll_bus_err(struct net_device *dev, u32 reg_esr)
{
        struct sk_buff *skb;
        struct can_frame *cf;

        skb = alloc_can_err_skb(dev, &cf);
        if (unlikely(!skb))
                return 0;

        do_bus_err(dev, cf, reg_esr);
        netif_receive_skb(skb);

        dev->stats.rx_packets++;
        dev->stats.rx_bytes += cf->can_dlc;

        return 1;
}

static void do_state(struct net_device *dev,
                     struct can_frame *cf, enum can_state new_state)
{
        struct flexcan_priv *priv = netdev_priv(dev);
        struct can_berr_counter bec;

        flexcan_get_berr_counter(dev, &bec);

        switch (priv->can.state) {
        case CAN_STATE_ERROR_ACTIVE:
                /*
                 * from: ERROR_ACTIVE
                 * to  : ERROR_WARNING, ERROR_PASSIVE, BUS_OFF
                 * =>  : there was a warning int
                 */
                if (new_state >= CAN_STATE_ERROR_WARNING &&
                    new_state <= CAN_STATE_BUS_OFF) {
                        netdev_dbg(dev, "Error Warning IRQ\n");
                        priv->can.can_stats.error_warning++;

                        cf->can_id |= CAN_ERR_CRTL;
                        cf->data[1] = (bec.txerr > bec.rxerr) ?
                                CAN_ERR_CRTL_TX_WARNING :
                                CAN_ERR_CRTL_RX_WARNING;
                }
        case CAN_STATE_ERROR_WARNING:   /* fallthrough */
                /*
                 * from: ERROR_ACTIVE, ERROR_WARNING
                 * to  : ERROR_PASSIVE, BUS_OFF
                 * =>  : error passive int
                 */
                if (new_state >= CAN_STATE_ERROR_PASSIVE &&
                    new_state <= CAN_STATE_BUS_OFF) {
                        netdev_dbg(dev, "Error Passive IRQ\n");
                        priv->can.can_stats.error_passive++;

                        cf->can_id |= CAN_ERR_CRTL;
                        cf->data[1] = (bec.txerr > bec.rxerr) ?
                                CAN_ERR_CRTL_TX_PASSIVE :
                                CAN_ERR_CRTL_RX_PASSIVE;
                }
                break;
        case CAN_STATE_BUS_OFF:
                netdev_err(dev, "BUG! "
                           "hardware recovered automatically from BUS_OFF\n");
                break;
        default:
                break;
        }

        /* process state changes depending on the new state */
        switch (new_state) {
        case CAN_STATE_ERROR_ACTIVE:
                netdev_dbg(dev, "Error Active\n");
                cf->can_id |= CAN_ERR_PROT;
                cf->data[2] = CAN_ERR_PROT_ACTIVE;
                break;
        case CAN_STATE_BUS_OFF:
                cf->can_id |= CAN_ERR_BUSOFF;
                can_bus_off(dev);
                break;
        default:
                break;
        }
}

static int flexcan_poll_state(struct net_device *dev, u32 reg_esr)
{
        struct flexcan_priv *priv = netdev_priv(dev);
        struct sk_buff *skb;
        struct can_frame *cf;
        enum can_state new_state;
        int flt;

        flt = reg_esr & FLEXCAN_ESR_FLT_CONF_MASK;
        if (likely(flt == FLEXCAN_ESR_FLT_CONF_ACTIVE)) {
                if (likely(!(reg_esr & (FLEXCAN_ESR_TX_WRN |
                                        FLEXCAN_ESR_RX_WRN))))
                        new_state = CAN_STATE_ERROR_ACTIVE;
                else
                        new_state = CAN_STATE_ERROR_WARNING;
        } else if (unlikely(flt == FLEXCAN_ESR_FLT_CONF_PASSIVE))
                new_state = CAN_STATE_ERROR_PASSIVE;
        else
                new_state = CAN_STATE_BUS_OFF;

        /* state hasn't changed */
        if (likely(new_state == priv->can.state))
                return 0;

        skb = alloc_can_err_skb(dev, &cf);
        if (unlikely(!skb))
                return 0;

        do_state(dev, cf, new_state);
        priv->can.state = new_state;
        netif_receive_skb(skb);

        dev->stats.rx_packets++;
        dev->stats.rx_bytes += cf->can_dlc;

        return 1;
}

static void flexcan_read_fifo(const struct net_device *dev,
                              struct can_frame *cf)
{
        const struct flexcan_priv *priv = netdev_priv(dev);
        struct flexcan_regs __iomem *regs = priv->base;
        struct flexcan_mb __iomem *mb = &regs->cantxfg[0];
        u32 reg_ctrl, reg_id;

        reg_ctrl = flexcan_read(&mb->can_ctrl);
        reg_id = flexcan_read(&mb->can_id);
        if (reg_ctrl & FLEXCAN_MB_CNT_IDE)
                cf->can_id = ((reg_id >> 0) & CAN_EFF_MASK) | CAN_EFF_FLAG;
        else
                cf->can_id = (reg_id >> 18) & CAN_SFF_MASK;

        if (reg_ctrl & FLEXCAN_MB_CNT_RTR)
                cf->can_id |= CAN_RTR_FLAG;
        cf->can_dlc = get_can_dlc((reg_ctrl >> 16) & 0xf);

        *(__be32 *)(cf->data + 0) = cpu_to_be32(flexcan_read(&mb->data[0]));
        *(__be32 *)(cf->data + 4) = cpu_to_be32(flexcan_read(&mb->data[1]));

        /* mark as read */
        flexcan_write(FLEXCAN_IFLAG_RX_FIFO_AVAILABLE, &regs->iflag1);
        flexcan_read(&regs->timer);
}

static int flexcan_read_frame(struct net_device *dev)
{
        struct net_device_stats *stats = &dev->stats;
        struct can_frame *cf;
        struct sk_buff *skb;

        skb = alloc_can_skb(dev, &cf);
        if (unlikely(!skb)) {
                stats->rx_dropped++;
                return 0;
        }

        flexcan_read_fifo(dev, cf);
        netif_receive_skb(skb);

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

        can_led_event(dev, CAN_LED_EVENT_RX);

        return 1;
}

static int flexcan_poll(struct napi_struct *napi, int quota)
{
        struct net_device *dev = napi->dev;
        const struct flexcan_priv *priv = netdev_priv(dev);
        struct flexcan_regs __iomem *regs = priv->base;
        u32 reg_iflag1, reg_esr;
        int work_done = 0;

        /*
         * The error bits are cleared on read,
         * use saved value from irq handler.
         */
        reg_esr = flexcan_read(&regs->esr) | priv->reg_esr;

        /* handle state changes */
        work_done += flexcan_poll_state(dev, reg_esr);

        /* handle RX-FIFO */
        reg_iflag1 = flexcan_read(&regs->iflag1);
        while (reg_iflag1 & FLEXCAN_IFLAG_RX_FIFO_AVAILABLE &&
               work_done < quota) {
                work_done += flexcan_read_frame(dev);
                reg_iflag1 = flexcan_read(&regs->iflag1);
        }

        /* report bus errors */
        if (flexcan_has_and_handle_berr(priv, reg_esr) && work_done < quota)
                work_done += flexcan_poll_bus_err(dev, reg_esr);

        if (work_done < quota) {
                napi_complete(napi);
                /* enable IRQs */
                flexcan_write(FLEXCAN_IFLAG_DEFAULT, &regs->imask1);
                flexcan_write(priv->reg_ctrl_default, &regs->ctrl);
        }

        return work_done;
}

static irqreturn_t flexcan_irq(int irq, void *dev_id)
{
        struct net_device *dev = dev_id;
        struct net_device_stats *stats = &dev->stats;
        struct flexcan_priv *priv = netdev_priv(dev);
        struct flexcan_regs __iomem *regs = priv->base;
        u32 reg_iflag1, reg_esr;

        reg_iflag1 = flexcan_read(&regs->iflag1);
        reg_esr = flexcan_read(&regs->esr);
        /* ACK all bus error and state change IRQ sources */
        if (reg_esr & FLEXCAN_ESR_ALL_INT)
                flexcan_write(reg_esr & FLEXCAN_ESR_ALL_INT, &regs->esr);

        /*
         * schedule NAPI in case of:
         * - rx IRQ
         * - state change IRQ
         * - bus error IRQ and bus error reporting is activated
         */
        if ((reg_iflag1 & FLEXCAN_IFLAG_RX_FIFO_AVAILABLE) ||
            (reg_esr & FLEXCAN_ESR_ERR_STATE) ||
            flexcan_has_and_handle_berr(priv, reg_esr)) {
                /*
                 * The error bits are cleared on read,
                 * save them for later use.
                 */
                priv->reg_esr = reg_esr & FLEXCAN_ESR_ERR_BUS;
                flexcan_write(FLEXCAN_IFLAG_DEFAULT &
                        ~FLEXCAN_IFLAG_RX_FIFO_AVAILABLE, &regs->imask1);
                flexcan_write(priv->reg_ctrl_default & ~FLEXCAN_CTRL_ERR_ALL,
                       &regs->ctrl);
                napi_schedule(&priv->napi);
        }

        /* FIFO overflow */
        if (reg_iflag1 & FLEXCAN_IFLAG_RX_FIFO_OVERFLOW) {
                flexcan_write(FLEXCAN_IFLAG_RX_FIFO_OVERFLOW, &regs->iflag1);
                dev->stats.rx_over_errors++;
                dev->stats.rx_errors++;
        }

        /* transmission complete interrupt */
        if (reg_iflag1 & (1 << FLEXCAN_TX_BUF_ID)) {
                stats->tx_bytes += can_get_echo_skb(dev, 0);
                stats->tx_packets++;
                can_led_event(dev, CAN_LED_EVENT_TX);
                flexcan_write((1 << FLEXCAN_TX_BUF_ID), &regs->iflag1);
                netif_wake_queue(dev);
        }

        return IRQ_HANDLED;
}

static void flexcan_set_bittiming(struct net_device *dev)
{
        const struct flexcan_priv *priv = netdev_priv(dev);
        const struct can_bittiming *bt = &priv->can.bittiming;
        struct flexcan_regs __iomem *regs = priv->base;
        u32 reg;

        reg = flexcan_read(&regs->ctrl);
        reg &= ~(FLEXCAN_CTRL_PRESDIV(0xff) |
                 FLEXCAN_CTRL_RJW(0x3) |
                 FLEXCAN_CTRL_PSEG1(0x7) |
                 FLEXCAN_CTRL_PSEG2(0x7) |
                 FLEXCAN_CTRL_PROPSEG(0x7) |
                 FLEXCAN_CTRL_LPB |
                 FLEXCAN_CTRL_SMP |
                 FLEXCAN_CTRL_LOM);

        reg |= FLEXCAN_CTRL_PRESDIV(bt->brp - 1) |
                FLEXCAN_CTRL_PSEG1(bt->phase_seg1 - 1) |
                FLEXCAN_CTRL_PSEG2(bt->phase_seg2 - 1) |
                FLEXCAN_CTRL_RJW(bt->sjw - 1) |
                FLEXCAN_CTRL_PROPSEG(bt->prop_seg - 1);

        if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
                reg |= FLEXCAN_CTRL_LPB;
        if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
                reg |= FLEXCAN_CTRL_LOM;
        if (priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES)
                reg |= FLEXCAN_CTRL_SMP;

        netdev_info(dev, "writing ctrl=0x%08x\n", reg);
        flexcan_write(reg, &regs->ctrl);

        /* print chip status */
        netdev_dbg(dev, "%s: mcr=0x%08x ctrl=0x%08x\n", __func__,
                   flexcan_read(&regs->mcr), flexcan_read(&regs->ctrl));
}

/*
 * flexcan_chip_start
 *
 * this functions is entered with clocks enabled
 *
 */
static int flexcan_chip_start(struct net_device *dev)
{
        struct flexcan_priv *priv = netdev_priv(dev);
        struct flexcan_regs __iomem *regs = priv->base;
        unsigned int i;
        int err;
        u32 reg_mcr, reg_ctrl;

        /* enable module */
        flexcan_chip_enable(priv);

        /* soft reset */
        flexcan_write(FLEXCAN_MCR_SOFTRST, &regs->mcr);
        udelay(10);

        reg_mcr = flexcan_read(&regs->mcr);
        if (reg_mcr & FLEXCAN_MCR_SOFTRST) {
                netdev_err(dev, "Failed to softreset can module (mcr=0x%08x)\n",
                           reg_mcr);
                err = -ENODEV;
                goto out;
        }

        flexcan_set_bittiming(dev);

        /*
         * MCR
         *
         * enable freeze
         * enable fifo
         * halt now
         * only supervisor access
         * enable warning int
         * choose format C
         * disable local echo
         *
         */
        reg_mcr = flexcan_read(&regs->mcr);
        reg_mcr |= FLEXCAN_MCR_FRZ | FLEXCAN_MCR_FEN | FLEXCAN_MCR_HALT |
                FLEXCAN_MCR_SUPV | FLEXCAN_MCR_WRN_EN |
                FLEXCAN_MCR_IDAM_C | FLEXCAN_MCR_SRX_DIS;
        netdev_dbg(dev, "%s: writing mcr=0x%08x", __func__, reg_mcr);
        flexcan_write(reg_mcr, &regs->mcr);

        /*
         * CTRL
         *
         * disable timer sync feature
         *
         * disable auto busoff recovery
         * transmit lowest buffer first
         *
         * enable tx and rx warning interrupt
         * enable bus off interrupt
         * (== FLEXCAN_CTRL_ERR_STATE)
         */
        reg_ctrl = flexcan_read(&regs->ctrl);
        reg_ctrl &= ~FLEXCAN_CTRL_TSYN;
        reg_ctrl |= FLEXCAN_CTRL_BOFF_REC | FLEXCAN_CTRL_LBUF |
                FLEXCAN_CTRL_ERR_STATE;
        /*
         * enable the "error interrupt" (FLEXCAN_CTRL_ERR_MSK),
         * on most Flexcan cores, too. Otherwise we don't get
         * any error warning or passive interrupts.
         */
        if (priv->devtype_data->features & FLEXCAN_HAS_BROKEN_ERR_STATE ||
            priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)
                reg_ctrl |= FLEXCAN_CTRL_ERR_MSK;

        /* save for later use */
        priv->reg_ctrl_default = reg_ctrl;
        netdev_dbg(dev, "%s: writing ctrl=0x%08x", __func__, reg_ctrl);
        flexcan_write(reg_ctrl, &regs->ctrl);

        for (i = 0; i < ARRAY_SIZE(regs->cantxfg); i++) {
                flexcan_write(0, &regs->cantxfg[i].can_ctrl);
                flexcan_write(0, &regs->cantxfg[i].can_id);
                flexcan_write(0, &regs->cantxfg[i].data[0]);
                flexcan_write(0, &regs->cantxfg[i].data[1]);

                /* put MB into rx queue */
                flexcan_write(FLEXCAN_MB_CNT_CODE(0x4),
                        &regs->cantxfg[i].can_ctrl);
        }

        /* acceptance mask/acceptance code (accept everything) */
        flexcan_write(0x0, &regs->rxgmask);
        flexcan_write(0x0, &regs->rx14mask);
        flexcan_write(0x0, &regs->rx15mask);

        if (priv->devtype_data->features & FLEXCAN_HAS_V10_FEATURES)
                flexcan_write(0x0, &regs->rxfgmask);

        if (priv->reg_xceiver)  {
                err = regulator_enable(priv->reg_xceiver);
                if (err)
                        goto out;
        }

        /* synchronize with the can bus */
        reg_mcr = flexcan_read(&regs->mcr);
        reg_mcr &= ~FLEXCAN_MCR_HALT;
        flexcan_write(reg_mcr, &regs->mcr);

        priv->can.state = CAN_STATE_ERROR_ACTIVE;

        /* enable FIFO interrupts */
        flexcan_write(FLEXCAN_IFLAG_DEFAULT, &regs->imask1);

        /* print chip status */
        netdev_dbg(dev, "%s: reading mcr=0x%08x ctrl=0x%08x\n", __func__,
                   flexcan_read(&regs->mcr), flexcan_read(&regs->ctrl));

        return 0;

 out:
        flexcan_chip_disable(priv);
        return err;
}

/*
 * flexcan_chip_stop
 *
 * this functions is entered with clocks enabled
 *
 */
static void flexcan_chip_stop(struct net_device *dev)
{
        struct flexcan_priv *priv = netdev_priv(dev);
        struct flexcan_regs __iomem *regs = priv->base;
        u32 reg;

        /* Disable all interrupts */
        flexcan_write(0, &regs->imask1);

        /* Disable + halt module */
        reg = flexcan_read(&regs->mcr);
        reg |= FLEXCAN_MCR_MDIS | FLEXCAN_MCR_HALT;
        flexcan_write(reg, &regs->mcr);

        if (priv->reg_xceiver)
                regulator_disable(priv->reg_xceiver);
        priv->can.state = CAN_STATE_STOPPED;

        return;
}

static int flexcan_open(struct net_device *dev)
{
        struct flexcan_priv *priv = netdev_priv(dev);
        int err;

        err = clk_prepare_enable(priv->clk_ipg);
        if (err)
                return err;

        err = clk_prepare_enable(priv->clk_per);
        if (err)
                goto out_disable_ipg;

        err = open_candev(dev);
        if (err)
                goto out_disable_per;

        err = request_irq(dev->irq, flexcan_irq, IRQF_SHARED, dev->name, dev);
        if (err)
                goto out_close;

        /* start chip and queuing */
        err = flexcan_chip_start(dev);
        if (err)
                goto out_close;

        can_led_event(dev, CAN_LED_EVENT_OPEN);

        napi_enable(&priv->napi);
        netif_start_queue(dev);

        return 0;

 out_close:
        close_candev(dev);
 out_disable_per:
        clk_disable_unprepare(priv->clk_per);
 out_disable_ipg:
        clk_disable_unprepare(priv->clk_ipg);

        return err;
}

static int flexcan_close(struct net_device *dev)
{
        struct flexcan_priv *priv = netdev_priv(dev);

        netif_stop_queue(dev);
        napi_disable(&priv->napi);
        flexcan_chip_stop(dev);

        free_irq(dev->irq, dev);
        clk_disable_unprepare(priv->clk_per);
        clk_disable_unprepare(priv->clk_ipg);

        close_candev(dev);

        can_led_event(dev, CAN_LED_EVENT_STOP);

        return 0;
}

static int flexcan_set_mode(struct net_device *dev, enum can_mode mode)
{
        int err;

        switch (mode) {
        case CAN_MODE_START:
                err = flexcan_chip_start(dev);
                if (err)
                        return err;

                netif_wake_queue(dev);
                break;

        default:
                return -EOPNOTSUPP;
        }

        return 0;
}

static const struct net_device_ops flexcan_netdev_ops = {
        .ndo_open       = flexcan_open,
        .ndo_stop       = flexcan_close,
        .ndo_start_xmit = flexcan_start_xmit,
};

static int register_flexcandev(struct net_device *dev)
{
        struct flexcan_priv *priv = netdev_priv(dev);
        struct flexcan_regs __iomem *regs = priv->base;
        u32 reg, err;

        err = clk_prepare_enable(priv->clk_ipg);
        if (err)
                return err;

        err = clk_prepare_enable(priv->clk_per);
        if (err)
                goto out_disable_ipg;

        /* select "bus clock", chip must be disabled */
        flexcan_chip_disable(priv);
        reg = flexcan_read(&regs->ctrl);
        reg |= FLEXCAN_CTRL_CLK_SRC;
        flexcan_write(reg, &regs->ctrl);

        flexcan_chip_enable(priv);

        /* set freeze, halt and activate FIFO, restrict register access */
        reg = flexcan_read(&regs->mcr);
        reg |= FLEXCAN_MCR_FRZ | FLEXCAN_MCR_HALT |
                FLEXCAN_MCR_FEN | FLEXCAN_MCR_SUPV;
        flexcan_write(reg, &regs->mcr);

        /*
         * Currently we only support newer versions of this core
         * featuring a RX FIFO. Older cores found on some Coldfire
         * derivates are not yet supported.
         */
        reg = flexcan_read(&regs->mcr);
        if (!(reg & FLEXCAN_MCR_FEN)) {
                netdev_err(dev, "Could not enable RX FIFO, unsupported core\n");
                err = -ENODEV;
                goto out_disable_per;
        }

        err = register_candev(dev);

 out_disable_per:
        /* disable core and turn off clocks */
        flexcan_chip_disable(priv);
        clk_disable_unprepare(priv->clk_per);
 out_disable_ipg:
        clk_disable_unprepare(priv->clk_ipg);

        return err;
}

static void unregister_flexcandev(struct net_device *dev)
{
        unregister_candev(dev);
}

static const struct of_device_id flexcan_of_match[] = {
        { .compatible = "fsl,p1010-flexcan", .data = &fsl_p1010_devtype_data, },
        { .compatible = "fsl,imx28-flexcan", .data = &fsl_imx28_devtype_data, },
        { .compatible = "fsl,imx6q-flexcan", .data = &fsl_imx6q_devtype_data, },
        { /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, flexcan_of_match);

static const struct platform_device_id flexcan_id_table[] = {
        { .name = "flexcan", .driver_data = (kernel_ulong_t)&fsl_p1010_devtype_data, },
        { /* sentinel */ },
};
MODULE_DEVICE_TABLE(platform, flexcan_id_table);

static int flexcan_probe(struct platform_device *pdev)
{
        const struct of_device_id *of_id;
        const struct flexcan_devtype_data *devtype_data;
        struct net_device *dev;
        struct flexcan_priv *priv;
        struct resource *mem;
        struct clk *clk_ipg = NULL, *clk_per = NULL;
        void __iomem *base;
        int err, irq;
        u32 clock_freq = 0;

        if (pdev->dev.of_node)
                of_property_read_u32(pdev->dev.of_node,
                                                "clock-frequency", &clock_freq);

        if (!clock_freq) {
                clk_ipg = devm_clk_get(&pdev->dev, "ipg");
                if (IS_ERR(clk_ipg)) {
                        dev_err(&pdev->dev, "no ipg clock defined\n");
                        return PTR_ERR(clk_ipg);
                }
                clock_freq = clk_get_rate(clk_ipg);

                clk_per = devm_clk_get(&pdev->dev, "per");
                if (IS_ERR(clk_per)) {
                        dev_err(&pdev->dev, "no per clock defined\n");
                        return PTR_ERR(clk_per);
                }
        }

        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        irq = platform_get_irq(pdev, 0);
        if (irq <= 0)
                return -ENODEV;

        base = devm_ioremap_resource(&pdev->dev, mem);
        if (IS_ERR(base))
                return PTR_ERR(base);

        of_id = of_match_device(flexcan_of_match, &pdev->dev);
        if (of_id) {
                devtype_data = of_id->data;
        } else if (pdev->id_entry->driver_data) {
                devtype_data = (struct flexcan_devtype_data *)
                        pdev->id_entry->driver_data;
        } else {
                return -ENODEV;
        }

        dev = alloc_candev(sizeof(struct flexcan_priv), 1);
        if (!dev)
                return -ENOMEM;

        dev->netdev_ops = &flexcan_netdev_ops;
        dev->irq = irq;
        dev->flags |= IFF_ECHO;

        priv = netdev_priv(dev);
        priv->can.clock.freq = clock_freq;
        priv->can.bittiming_const = &flexcan_bittiming_const;
        priv->can.do_set_mode = flexcan_set_mode;
        priv->can.do_get_berr_counter = flexcan_get_berr_counter;
        priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
                CAN_CTRLMODE_LISTENONLY | CAN_CTRLMODE_3_SAMPLES |
                CAN_CTRLMODE_BERR_REPORTING;
        priv->base = base;
        priv->dev = dev;
        priv->clk_ipg = clk_ipg;
        priv->clk_per = clk_per;
        priv->pdata = pdev->dev.platform_data;
        priv->devtype_data = devtype_data;

        priv->reg_xceiver = devm_regulator_get(&pdev->dev, "xceiver");
        if (IS_ERR(priv->reg_xceiver))
                priv->reg_xceiver = NULL;

        netif_napi_add(dev, &priv->napi, flexcan_poll, FLEXCAN_NAPI_WEIGHT);

        platform_set_drvdata(pdev, dev);
        SET_NETDEV_DEV(dev, &pdev->dev);

        err = register_flexcandev(dev);
        if (err) {
                dev_err(&pdev->dev, "registering netdev failed\n");
                goto failed_register;
        }

        devm_can_led_init(dev);

        dev_info(&pdev->dev, "device registered (reg_base=%p, irq=%d)\n",
                 priv->base, dev->irq);

        return 0;

 failed_register:
        free_candev(dev);
        return err;
}

static int flexcan_remove(struct platform_device *pdev)
{
        struct net_device *dev = platform_get_drvdata(pdev);

        unregister_flexcandev(dev);

        free_candev(dev);

        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int flexcan_suspend(struct device *device)
{
        struct net_device *dev = dev_get_drvdata(device);
        struct flexcan_priv *priv = netdev_priv(dev);

        flexcan_chip_disable(priv);

        if (netif_running(dev)) {
                netif_stop_queue(dev);
                netif_device_detach(dev);
        }
        priv->can.state = CAN_STATE_SLEEPING;

        return 0;
}

static int flexcan_resume(struct device *device)
{
        struct net_device *dev = dev_get_drvdata(device);
        struct flexcan_priv *priv = netdev_priv(dev);

        priv->can.state = CAN_STATE_ERROR_ACTIVE;
        if (netif_running(dev)) {
                netif_device_attach(dev);
                netif_start_queue(dev);
        }
        flexcan_chip_enable(priv);

        return 0;
}
#endif /* CONFIG_PM_SLEEP */

static SIMPLE_DEV_PM_OPS(flexcan_pm_ops, flexcan_suspend, flexcan_resume);

static struct platform_driver flexcan_driver = {
        .driver = {
                .name = DRV_NAME,
                .owner = THIS_MODULE,
                .pm = &flexcan_pm_ops,
                .of_match_table = flexcan_of_match,
        },
        .probe = flexcan_probe,
        .remove = flexcan_remove,
        .id_table = flexcan_id_table,
};

module_platform_driver(flexcan_driver);

MODULE_AUTHOR("Sascha Hauer <kernel@pengutronix.de>, "
              "Marc Kleine-Budde <kernel@pengutronix.de>");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("CAN port driver for flexcan based chip");