Linux 4.19.133

[linux/fpc-iii.git] / drivers / net / can / spi / mcp251x.c

/*
 * CAN bus driver for Microchip 251x/25625 CAN Controller with SPI Interface
 *
 * MCP2510 support and bug fixes by Christian Pellegrin
 * <chripell@evolware.org>
 *
 * Copyright 2009 Christian Pellegrin EVOL S.r.l.
 *
 * Copyright 2007 Raymarine UK, Ltd. All Rights Reserved.
 * Written under contract by:
 *   Chris Elston, Katalix Systems, Ltd.
 *
 * Based on Microchip MCP251x CAN controller driver written by
 * David Vrabel, Copyright 2006 Arcom Control Systems Ltd.
 *
 * Based on CAN bus driver for the CCAN controller written by
 * - Sascha Hauer, Marc Kleine-Budde, Pengutronix
 * - Simon Kallweit, intefo AG
 * Copyright 2007
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the version 2 of the GNU General Public License
 * as published by the Free Software Foundation
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 *
 *
 *
 * Your platform definition file should specify something like:
 *
 * static struct mcp251x_platform_data mcp251x_info = {
 *         .oscillator_frequency = 8000000,
 * };
 *
 * static struct spi_board_info spi_board_info[] = {
 *         {
 *                 .modalias = "mcp2510",
 *                      // "mcp2515" or "mcp25625" depending on your controller
 *                 .platform_data = &mcp251x_info,
 *                 .irq = IRQ_EINT13,
 *                 .max_speed_hz = 2*1000*1000,
 *                 .chip_select = 2,
 *         },
 * };
 *
 * Please see mcp251x.h for a description of the fields in
 * struct mcp251x_platform_data.
 *
 */

#include <linux/can/core.h>
#include <linux/can/dev.h>
#include <linux/can/led.h>
#include <linux/can/platform/mcp251x.h>
#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/freezer.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>
#include <linux/uaccess.h>
#include <linux/regulator/consumer.h>

/* SPI interface instruction set */
#define INSTRUCTION_WRITE       0x02
#define INSTRUCTION_READ        0x03
#define INSTRUCTION_BIT_MODIFY  0x05
#define INSTRUCTION_LOAD_TXB(n) (0x40 + 2 * (n))
#define INSTRUCTION_READ_RXB(n) (((n) == 0) ? 0x90 : 0x94)
#define INSTRUCTION_RESET       0xC0
#define RTS_TXB0                0x01
#define RTS_TXB1                0x02
#define RTS_TXB2                0x04
#define INSTRUCTION_RTS(n)      (0x80 | ((n) & 0x07))


/* MPC251x registers */
#define CANSTAT       0x0e
#define CANCTRL       0x0f
#  define CANCTRL_REQOP_MASK        0xe0
#  define CANCTRL_REQOP_CONF        0x80
#  define CANCTRL_REQOP_LISTEN_ONLY 0x60
#  define CANCTRL_REQOP_LOOPBACK    0x40
#  define CANCTRL_REQOP_SLEEP       0x20
#  define CANCTRL_REQOP_NORMAL      0x00
#  define CANCTRL_OSM               0x08
#  define CANCTRL_ABAT              0x10
#define TEC           0x1c
#define REC           0x1d
#define CNF1          0x2a
#  define CNF1_SJW_SHIFT   6
#define CNF2          0x29
#  define CNF2_BTLMODE     0x80
#  define CNF2_SAM         0x40
#  define CNF2_PS1_SHIFT   3
#define CNF3          0x28
#  define CNF3_SOF         0x08
#  define CNF3_WAKFIL      0x04
#  define CNF3_PHSEG2_MASK 0x07
#define CANINTE       0x2b
#  define CANINTE_MERRE 0x80
#  define CANINTE_WAKIE 0x40
#  define CANINTE_ERRIE 0x20
#  define CANINTE_TX2IE 0x10
#  define CANINTE_TX1IE 0x08
#  define CANINTE_TX0IE 0x04
#  define CANINTE_RX1IE 0x02
#  define CANINTE_RX0IE 0x01
#define CANINTF       0x2c
#  define CANINTF_MERRF 0x80
#  define CANINTF_WAKIF 0x40
#  define CANINTF_ERRIF 0x20
#  define CANINTF_TX2IF 0x10
#  define CANINTF_TX1IF 0x08
#  define CANINTF_TX0IF 0x04
#  define CANINTF_RX1IF 0x02
#  define CANINTF_RX0IF 0x01
#  define CANINTF_RX (CANINTF_RX0IF | CANINTF_RX1IF)
#  define CANINTF_TX (CANINTF_TX2IF | CANINTF_TX1IF | CANINTF_TX0IF)
#  define CANINTF_ERR (CANINTF_ERRIF)
#define EFLG          0x2d
#  define EFLG_EWARN    0x01
#  define EFLG_RXWAR    0x02
#  define EFLG_TXWAR    0x04
#  define EFLG_RXEP     0x08
#  define EFLG_TXEP     0x10
#  define EFLG_TXBO     0x20
#  define EFLG_RX0OVR   0x40
#  define EFLG_RX1OVR   0x80
#define TXBCTRL(n)  (((n) * 0x10) + 0x30 + TXBCTRL_OFF)
#  define TXBCTRL_ABTF  0x40
#  define TXBCTRL_MLOA  0x20
#  define TXBCTRL_TXERR 0x10
#  define TXBCTRL_TXREQ 0x08
#define TXBSIDH(n)  (((n) * 0x10) + 0x30 + TXBSIDH_OFF)
#  define SIDH_SHIFT    3
#define TXBSIDL(n)  (((n) * 0x10) + 0x30 + TXBSIDL_OFF)
#  define SIDL_SID_MASK    7
#  define SIDL_SID_SHIFT   5
#  define SIDL_EXIDE_SHIFT 3
#  define SIDL_EID_SHIFT   16
#  define SIDL_EID_MASK    3
#define TXBEID8(n)  (((n) * 0x10) + 0x30 + TXBEID8_OFF)
#define TXBEID0(n)  (((n) * 0x10) + 0x30 + TXBEID0_OFF)
#define TXBDLC(n)   (((n) * 0x10) + 0x30 + TXBDLC_OFF)
#  define DLC_RTR_SHIFT    6
#define TXBCTRL_OFF 0
#define TXBSIDH_OFF 1
#define TXBSIDL_OFF 2
#define TXBEID8_OFF 3
#define TXBEID0_OFF 4
#define TXBDLC_OFF  5
#define TXBDAT_OFF  6
#define RXBCTRL(n)  (((n) * 0x10) + 0x60 + RXBCTRL_OFF)
#  define RXBCTRL_BUKT  0x04
#  define RXBCTRL_RXM0  0x20
#  define RXBCTRL_RXM1  0x40
#define RXBSIDH(n)  (((n) * 0x10) + 0x60 + RXBSIDH_OFF)
#  define RXBSIDH_SHIFT 3
#define RXBSIDL(n)  (((n) * 0x10) + 0x60 + RXBSIDL_OFF)
#  define RXBSIDL_IDE   0x08
#  define RXBSIDL_SRR   0x10
#  define RXBSIDL_EID   3
#  define RXBSIDL_SHIFT 5
#define RXBEID8(n)  (((n) * 0x10) + 0x60 + RXBEID8_OFF)
#define RXBEID0(n)  (((n) * 0x10) + 0x60 + RXBEID0_OFF)
#define RXBDLC(n)   (((n) * 0x10) + 0x60 + RXBDLC_OFF)
#  define RXBDLC_LEN_MASK  0x0f
#  define RXBDLC_RTR       0x40
#define RXBCTRL_OFF 0
#define RXBSIDH_OFF 1
#define RXBSIDL_OFF 2
#define RXBEID8_OFF 3
#define RXBEID0_OFF 4
#define RXBDLC_OFF  5
#define RXBDAT_OFF  6
#define RXFSID(n) ((n < 3) ? 0 : 4)
#define RXFSIDH(n) ((n) * 4 + RXFSID(n))
#define RXFSIDL(n) ((n) * 4 + 1 + RXFSID(n))
#define RXFEID8(n) ((n) * 4 + 2 + RXFSID(n))
#define RXFEID0(n) ((n) * 4 + 3 + RXFSID(n))
#define RXMSIDH(n) ((n) * 4 + 0x20)
#define RXMSIDL(n) ((n) * 4 + 0x21)
#define RXMEID8(n) ((n) * 4 + 0x22)
#define RXMEID0(n) ((n) * 4 + 0x23)

#define GET_BYTE(val, byte)                     \
        (((val) >> ((byte) * 8)) & 0xff)
#define SET_BYTE(val, byte)                     \
        (((val) & 0xff) << ((byte) * 8))

/*
 * Buffer size required for the largest SPI transfer (i.e., reading a
 * frame)
 */
#define CAN_FRAME_MAX_DATA_LEN  8
#define SPI_TRANSFER_BUF_LEN    (6 + CAN_FRAME_MAX_DATA_LEN)
#define CAN_FRAME_MAX_BITS      128

#define TX_ECHO_SKB_MAX 1

#define MCP251X_OST_DELAY_MS    (5)

#define DEVICE_NAME "mcp251x"

static int mcp251x_enable_dma; /* Enable SPI DMA. Default: 0 (Off) */
module_param(mcp251x_enable_dma, int, 0444);
MODULE_PARM_DESC(mcp251x_enable_dma, "Enable SPI DMA. Default: 0 (Off)");

static const struct can_bittiming_const mcp251x_bittiming_const = {
        .name = DEVICE_NAME,
        .tseg1_min = 3,
        .tseg1_max = 16,
        .tseg2_min = 2,
        .tseg2_max = 8,
        .sjw_max = 4,
        .brp_min = 1,
        .brp_max = 64,
        .brp_inc = 1,
};

enum mcp251x_model {
        CAN_MCP251X_MCP2510     = 0x2510,
        CAN_MCP251X_MCP2515     = 0x2515,
        CAN_MCP251X_MCP25625    = 0x25625,
};

struct mcp251x_priv {
        struct can_priv    can;
        struct net_device *net;
        struct spi_device *spi;
        enum mcp251x_model model;

        struct mutex mcp_lock; /* SPI device lock */

        u8 *spi_tx_buf;
        u8 *spi_rx_buf;
        dma_addr_t spi_tx_dma;
        dma_addr_t spi_rx_dma;

        struct sk_buff *tx_skb;
        int tx_len;

        struct workqueue_struct *wq;
        struct work_struct tx_work;
        struct work_struct restart_work;

        int force_quit;
        int after_suspend;
#define AFTER_SUSPEND_UP 1
#define AFTER_SUSPEND_DOWN 2
#define AFTER_SUSPEND_POWER 4
#define AFTER_SUSPEND_RESTART 8
        int restart_tx;
        struct regulator *power;
        struct regulator *transceiver;
        struct clk *clk;
};

#define MCP251X_IS(_model) \
static inline int mcp251x_is_##_model(struct spi_device *spi) \
{ \
        struct mcp251x_priv *priv = spi_get_drvdata(spi); \
        return priv->model == CAN_MCP251X_MCP##_model; \
}

MCP251X_IS(2510);

static void mcp251x_clean(struct net_device *net)
{
        struct mcp251x_priv *priv = netdev_priv(net);

        if (priv->tx_skb || priv->tx_len)
                net->stats.tx_errors++;
        if (priv->tx_skb)
                dev_kfree_skb(priv->tx_skb);
        if (priv->tx_len)
                can_free_echo_skb(priv->net, 0);
        priv->tx_skb = NULL;
        priv->tx_len = 0;
}

/*
 * Note about handling of error return of mcp251x_spi_trans: accessing
 * registers via SPI is not really different conceptually than using
 * normal I/O assembler instructions, although it's much more
 * complicated from a practical POV. So it's not advisable to always
 * check the return value of this function. Imagine that every
 * read{b,l}, write{b,l} and friends would be bracketed in "if ( < 0)
 * error();", it would be a great mess (well there are some situation
 * when exception handling C++ like could be useful after all). So we
 * just check that transfers are OK at the beginning of our
 * conversation with the chip and to avoid doing really nasty things
 * (like injecting bogus packets in the network stack).
 */
static int mcp251x_spi_trans(struct spi_device *spi, int len)
{
        struct mcp251x_priv *priv = spi_get_drvdata(spi);
        struct spi_transfer t = {
                .tx_buf = priv->spi_tx_buf,
                .rx_buf = priv->spi_rx_buf,
                .len = len,
                .cs_change = 0,
        };
        struct spi_message m;
        int ret;

        spi_message_init(&m);

        if (mcp251x_enable_dma) {
                t.tx_dma = priv->spi_tx_dma;
                t.rx_dma = priv->spi_rx_dma;
                m.is_dma_mapped = 1;
        }

        spi_message_add_tail(&t, &m);

        ret = spi_sync(spi, &m);
        if (ret)
                dev_err(&spi->dev, "spi transfer failed: ret = %d\n", ret);
        return ret;
}

static u8 mcp251x_read_reg(struct spi_device *spi, uint8_t reg)
{
        struct mcp251x_priv *priv = spi_get_drvdata(spi);
        u8 val = 0;

        priv->spi_tx_buf[0] = INSTRUCTION_READ;
        priv->spi_tx_buf[1] = reg;

        mcp251x_spi_trans(spi, 3);
        val = priv->spi_rx_buf[2];

        return val;
}

static void mcp251x_read_2regs(struct spi_device *spi, uint8_t reg,
                uint8_t *v1, uint8_t *v2)
{
        struct mcp251x_priv *priv = spi_get_drvdata(spi);

        priv->spi_tx_buf[0] = INSTRUCTION_READ;
        priv->spi_tx_buf[1] = reg;

        mcp251x_spi_trans(spi, 4);

        *v1 = priv->spi_rx_buf[2];
        *v2 = priv->spi_rx_buf[3];
}

static void mcp251x_write_reg(struct spi_device *spi, u8 reg, uint8_t val)
{
        struct mcp251x_priv *priv = spi_get_drvdata(spi);

        priv->spi_tx_buf[0] = INSTRUCTION_WRITE;
        priv->spi_tx_buf[1] = reg;
        priv->spi_tx_buf[2] = val;

        mcp251x_spi_trans(spi, 3);
}

static void mcp251x_write_bits(struct spi_device *spi, u8 reg,
                               u8 mask, uint8_t val)
{
        struct mcp251x_priv *priv = spi_get_drvdata(spi);

        priv->spi_tx_buf[0] = INSTRUCTION_BIT_MODIFY;
        priv->spi_tx_buf[1] = reg;
        priv->spi_tx_buf[2] = mask;
        priv->spi_tx_buf[3] = val;

        mcp251x_spi_trans(spi, 4);
}

static void mcp251x_hw_tx_frame(struct spi_device *spi, u8 *buf,
                                int len, int tx_buf_idx)
{
        struct mcp251x_priv *priv = spi_get_drvdata(spi);

        if (mcp251x_is_2510(spi)) {
                int i;

                for (i = 1; i < TXBDAT_OFF + len; i++)
                        mcp251x_write_reg(spi, TXBCTRL(tx_buf_idx) + i,
                                          buf[i]);
        } else {
                memcpy(priv->spi_tx_buf, buf, TXBDAT_OFF + len);
                mcp251x_spi_trans(spi, TXBDAT_OFF + len);
        }
}

static void mcp251x_hw_tx(struct spi_device *spi, struct can_frame *frame,
                          int tx_buf_idx)
{
        struct mcp251x_priv *priv = spi_get_drvdata(spi);
        u32 sid, eid, exide, rtr;
        u8 buf[SPI_TRANSFER_BUF_LEN];

        exide = (frame->can_id & CAN_EFF_FLAG) ? 1 : 0; /* Extended ID Enable */
        if (exide)
                sid = (frame->can_id & CAN_EFF_MASK) >> 18;
        else
                sid = frame->can_id & CAN_SFF_MASK; /* Standard ID */
        eid = frame->can_id & CAN_EFF_MASK; /* Extended ID */
        rtr = (frame->can_id & CAN_RTR_FLAG) ? 1 : 0; /* Remote transmission */

        buf[TXBCTRL_OFF] = INSTRUCTION_LOAD_TXB(tx_buf_idx);
        buf[TXBSIDH_OFF] = sid >> SIDH_SHIFT;
        buf[TXBSIDL_OFF] = ((sid & SIDL_SID_MASK) << SIDL_SID_SHIFT) |
                (exide << SIDL_EXIDE_SHIFT) |
                ((eid >> SIDL_EID_SHIFT) & SIDL_EID_MASK);
        buf[TXBEID8_OFF] = GET_BYTE(eid, 1);
        buf[TXBEID0_OFF] = GET_BYTE(eid, 0);
        buf[TXBDLC_OFF] = (rtr << DLC_RTR_SHIFT) | frame->can_dlc;
        memcpy(buf + TXBDAT_OFF, frame->data, frame->can_dlc);
        mcp251x_hw_tx_frame(spi, buf, frame->can_dlc, tx_buf_idx);

        /* use INSTRUCTION_RTS, to avoid "repeated frame problem" */
        priv->spi_tx_buf[0] = INSTRUCTION_RTS(1 << tx_buf_idx);
        mcp251x_spi_trans(priv->spi, 1);
}

static void mcp251x_hw_rx_frame(struct spi_device *spi, u8 *buf,
                                int buf_idx)
{
        struct mcp251x_priv *priv = spi_get_drvdata(spi);

        if (mcp251x_is_2510(spi)) {
                int i, len;

                for (i = 1; i < RXBDAT_OFF; i++)
                        buf[i] = mcp251x_read_reg(spi, RXBCTRL(buf_idx) + i);

                len = get_can_dlc(buf[RXBDLC_OFF] & RXBDLC_LEN_MASK);
                for (; i < (RXBDAT_OFF + len); i++)
                        buf[i] = mcp251x_read_reg(spi, RXBCTRL(buf_idx) + i);
        } else {
                priv->spi_tx_buf[RXBCTRL_OFF] = INSTRUCTION_READ_RXB(buf_idx);
                mcp251x_spi_trans(spi, SPI_TRANSFER_BUF_LEN);
                memcpy(buf, priv->spi_rx_buf, SPI_TRANSFER_BUF_LEN);
        }
}

static void mcp251x_hw_rx(struct spi_device *spi, int buf_idx)
{
        struct mcp251x_priv *priv = spi_get_drvdata(spi);
        struct sk_buff *skb;
        struct can_frame *frame;
        u8 buf[SPI_TRANSFER_BUF_LEN];

        skb = alloc_can_skb(priv->net, &frame);
        if (!skb) {
                dev_err(&spi->dev, "cannot allocate RX skb\n");
                priv->net->stats.rx_dropped++;
                return;
        }

        mcp251x_hw_rx_frame(spi, buf, buf_idx);
        if (buf[RXBSIDL_OFF] & RXBSIDL_IDE) {
                /* Extended ID format */
                frame->can_id = CAN_EFF_FLAG;
                frame->can_id |=
                        /* Extended ID part */
                        SET_BYTE(buf[RXBSIDL_OFF] & RXBSIDL_EID, 2) |
                        SET_BYTE(buf[RXBEID8_OFF], 1) |
                        SET_BYTE(buf[RXBEID0_OFF], 0) |
                        /* Standard ID part */
                        (((buf[RXBSIDH_OFF] << RXBSIDH_SHIFT) |
                          (buf[RXBSIDL_OFF] >> RXBSIDL_SHIFT)) << 18);
                /* Remote transmission request */
                if (buf[RXBDLC_OFF] & RXBDLC_RTR)
                        frame->can_id |= CAN_RTR_FLAG;
        } else {
                /* Standard ID format */
                frame->can_id =
                        (buf[RXBSIDH_OFF] << RXBSIDH_SHIFT) |
                        (buf[RXBSIDL_OFF] >> RXBSIDL_SHIFT);
                if (buf[RXBSIDL_OFF] & RXBSIDL_SRR)
                        frame->can_id |= CAN_RTR_FLAG;
        }
        /* Data length */
        frame->can_dlc = get_can_dlc(buf[RXBDLC_OFF] & RXBDLC_LEN_MASK);
        memcpy(frame->data, buf + RXBDAT_OFF, frame->can_dlc);

        priv->net->stats.rx_packets++;
        priv->net->stats.rx_bytes += frame->can_dlc;

        can_led_event(priv->net, CAN_LED_EVENT_RX);

        netif_rx_ni(skb);
}

static void mcp251x_hw_sleep(struct spi_device *spi)
{
        mcp251x_write_reg(spi, CANCTRL, CANCTRL_REQOP_SLEEP);
}

static netdev_tx_t mcp251x_hard_start_xmit(struct sk_buff *skb,
                                           struct net_device *net)
{
        struct mcp251x_priv *priv = netdev_priv(net);
        struct spi_device *spi = priv->spi;

        if (priv->tx_skb || priv->tx_len) {
                dev_warn(&spi->dev, "hard_xmit called while tx busy\n");
                return NETDEV_TX_BUSY;
        }

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

        netif_stop_queue(net);
        priv->tx_skb = skb;
        queue_work(priv->wq, &priv->tx_work);

        return NETDEV_TX_OK;
}

static int mcp251x_do_set_mode(struct net_device *net, enum can_mode mode)
{
        struct mcp251x_priv *priv = netdev_priv(net);

        switch (mode) {
        case CAN_MODE_START:
                mcp251x_clean(net);
                /* We have to delay work since SPI I/O may sleep */
                priv->can.state = CAN_STATE_ERROR_ACTIVE;
                priv->restart_tx = 1;
                if (priv->can.restart_ms == 0)
                        priv->after_suspend = AFTER_SUSPEND_RESTART;
                queue_work(priv->wq, &priv->restart_work);
                break;
        default:
                return -EOPNOTSUPP;
        }

        return 0;
}

static int mcp251x_set_normal_mode(struct spi_device *spi)
{
        struct mcp251x_priv *priv = spi_get_drvdata(spi);
        unsigned long timeout;

        /* Enable interrupts */
        mcp251x_write_reg(spi, CANINTE,
                          CANINTE_ERRIE | CANINTE_TX2IE | CANINTE_TX1IE |
                          CANINTE_TX0IE | CANINTE_RX1IE | CANINTE_RX0IE);

        if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK) {
                /* Put device into loopback mode */
                mcp251x_write_reg(spi, CANCTRL, CANCTRL_REQOP_LOOPBACK);
        } else if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) {
                /* Put device into listen-only mode */
                mcp251x_write_reg(spi, CANCTRL, CANCTRL_REQOP_LISTEN_ONLY);
        } else {
                /* Put device into normal mode */
                mcp251x_write_reg(spi, CANCTRL, CANCTRL_REQOP_NORMAL);

                /* Wait for the device to enter normal mode */
                timeout = jiffies + HZ;
                while (mcp251x_read_reg(spi, CANSTAT) & CANCTRL_REQOP_MASK) {
                        schedule();
                        if (time_after(jiffies, timeout)) {
                                dev_err(&spi->dev, "MCP251x didn't"
                                        " enter in normal mode\n");
                                return -EBUSY;
                        }
                }
        }
        priv->can.state = CAN_STATE_ERROR_ACTIVE;
        return 0;
}

static int mcp251x_do_set_bittiming(struct net_device *net)
{
        struct mcp251x_priv *priv = netdev_priv(net);
        struct can_bittiming *bt = &priv->can.bittiming;
        struct spi_device *spi = priv->spi;

        mcp251x_write_reg(spi, CNF1, ((bt->sjw - 1) << CNF1_SJW_SHIFT) |
                          (bt->brp - 1));
        mcp251x_write_reg(spi, CNF2, CNF2_BTLMODE |
                          (priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES ?
                           CNF2_SAM : 0) |
                          ((bt->phase_seg1 - 1) << CNF2_PS1_SHIFT) |
                          (bt->prop_seg - 1));
        mcp251x_write_bits(spi, CNF3, CNF3_PHSEG2_MASK,
                           (bt->phase_seg2 - 1));
        dev_dbg(&spi->dev, "CNF: 0x%02x 0x%02x 0x%02x\n",
                mcp251x_read_reg(spi, CNF1),
                mcp251x_read_reg(spi, CNF2),
                mcp251x_read_reg(spi, CNF3));

        return 0;
}

static int mcp251x_setup(struct net_device *net, struct spi_device *spi)
{
        mcp251x_do_set_bittiming(net);

        mcp251x_write_reg(spi, RXBCTRL(0),
                          RXBCTRL_BUKT | RXBCTRL_RXM0 | RXBCTRL_RXM1);
        mcp251x_write_reg(spi, RXBCTRL(1),
                          RXBCTRL_RXM0 | RXBCTRL_RXM1);
        return 0;
}

static int mcp251x_hw_reset(struct spi_device *spi)
{
        struct mcp251x_priv *priv = spi_get_drvdata(spi);
        unsigned long timeout;
        int ret;

        /* Wait for oscillator startup timer after power up */
        mdelay(MCP251X_OST_DELAY_MS);

        priv->spi_tx_buf[0] = INSTRUCTION_RESET;
        ret = mcp251x_spi_trans(spi, 1);
        if (ret)
                return ret;

        /* Wait for oscillator startup timer after reset */
        mdelay(MCP251X_OST_DELAY_MS);

        /* Wait for reset to finish */
        timeout = jiffies + HZ;
        while ((mcp251x_read_reg(spi, CANSTAT) & CANCTRL_REQOP_MASK) !=
               CANCTRL_REQOP_CONF) {
                usleep_range(MCP251X_OST_DELAY_MS * 1000,
                             MCP251X_OST_DELAY_MS * 1000 * 2);

                if (time_after(jiffies, timeout)) {
                        dev_err(&spi->dev,
                                "MCP251x didn't enter in conf mode after reset\n");
                        return -EBUSY;
                }
        }
        return 0;
}

static int mcp251x_hw_probe(struct spi_device *spi)
{
        u8 ctrl;
        int ret;

        ret = mcp251x_hw_reset(spi);
        if (ret)
                return ret;

        ctrl = mcp251x_read_reg(spi, CANCTRL);

        dev_dbg(&spi->dev, "CANCTRL 0x%02x\n", ctrl);

        /* Check for power up default value */
        if ((ctrl & 0x17) != 0x07)
                return -ENODEV;

        return 0;
}

static int mcp251x_power_enable(struct regulator *reg, int enable)
{
        if (IS_ERR_OR_NULL(reg))
                return 0;

        if (enable)
                return regulator_enable(reg);
        else
                return regulator_disable(reg);
}

static int mcp251x_stop(struct net_device *net)
{
        struct mcp251x_priv *priv = netdev_priv(net);
        struct spi_device *spi = priv->spi;

        close_candev(net);

        priv->force_quit = 1;
        free_irq(spi->irq, priv);
        destroy_workqueue(priv->wq);
        priv->wq = NULL;

        mutex_lock(&priv->mcp_lock);

        /* Disable and clear pending interrupts */
        mcp251x_write_reg(spi, CANINTE, 0x00);
        mcp251x_write_reg(spi, CANINTF, 0x00);

        mcp251x_write_reg(spi, TXBCTRL(0), 0);
        mcp251x_clean(net);

        mcp251x_hw_sleep(spi);

        mcp251x_power_enable(priv->transceiver, 0);

        priv->can.state = CAN_STATE_STOPPED;

        mutex_unlock(&priv->mcp_lock);

        can_led_event(net, CAN_LED_EVENT_STOP);

        return 0;
}

static void mcp251x_error_skb(struct net_device *net, int can_id, int data1)
{
        struct sk_buff *skb;
        struct can_frame *frame;

        skb = alloc_can_err_skb(net, &frame);
        if (skb) {
                frame->can_id |= can_id;
                frame->data[1] = data1;
                netif_rx_ni(skb);
        } else {
                netdev_err(net, "cannot allocate error skb\n");
        }
}

static void mcp251x_tx_work_handler(struct work_struct *ws)
{
        struct mcp251x_priv *priv = container_of(ws, struct mcp251x_priv,
                                                 tx_work);
        struct spi_device *spi = priv->spi;
        struct net_device *net = priv->net;
        struct can_frame *frame;

        mutex_lock(&priv->mcp_lock);
        if (priv->tx_skb) {
                if (priv->can.state == CAN_STATE_BUS_OFF) {
                        mcp251x_clean(net);
                } else {
                        frame = (struct can_frame *)priv->tx_skb->data;

                        if (frame->can_dlc > CAN_FRAME_MAX_DATA_LEN)
                                frame->can_dlc = CAN_FRAME_MAX_DATA_LEN;
                        mcp251x_hw_tx(spi, frame, 0);
                        priv->tx_len = 1 + frame->can_dlc;
                        can_put_echo_skb(priv->tx_skb, net, 0);
                        priv->tx_skb = NULL;
                }
        }
        mutex_unlock(&priv->mcp_lock);
}

static void mcp251x_restart_work_handler(struct work_struct *ws)
{
        struct mcp251x_priv *priv = container_of(ws, struct mcp251x_priv,
                                                 restart_work);
        struct spi_device *spi = priv->spi;
        struct net_device *net = priv->net;

        mutex_lock(&priv->mcp_lock);
        if (priv->after_suspend) {
                mcp251x_hw_reset(spi);
                mcp251x_setup(net, spi);
                priv->force_quit = 0;
                if (priv->after_suspend & AFTER_SUSPEND_RESTART) {
                        mcp251x_set_normal_mode(spi);
                } else if (priv->after_suspend & AFTER_SUSPEND_UP) {
                        netif_device_attach(net);
                        mcp251x_clean(net);
                        mcp251x_set_normal_mode(spi);
                        netif_wake_queue(net);
                } else {
                        mcp251x_hw_sleep(spi);
                }
                priv->after_suspend = 0;
        }

        if (priv->restart_tx) {
                priv->restart_tx = 0;
                mcp251x_write_reg(spi, TXBCTRL(0), 0);
                mcp251x_clean(net);
                netif_wake_queue(net);
                mcp251x_error_skb(net, CAN_ERR_RESTARTED, 0);
        }
        mutex_unlock(&priv->mcp_lock);
}

static irqreturn_t mcp251x_can_ist(int irq, void *dev_id)
{
        struct mcp251x_priv *priv = dev_id;
        struct spi_device *spi = priv->spi;
        struct net_device *net = priv->net;

        mutex_lock(&priv->mcp_lock);
        while (!priv->force_quit) {
                enum can_state new_state;
                u8 intf, eflag;
                u8 clear_intf = 0;
                int can_id = 0, data1 = 0;

                mcp251x_read_2regs(spi, CANINTF, &intf, &eflag);

                /* mask out flags we don't care about */
                intf &= CANINTF_RX | CANINTF_TX | CANINTF_ERR;

                /* receive buffer 0 */
                if (intf & CANINTF_RX0IF) {
                        mcp251x_hw_rx(spi, 0);
                        /* Free one buffer ASAP
                         * (The MCP2515/25625 does this automatically.)
                         */
                        if (mcp251x_is_2510(spi))
                                mcp251x_write_bits(spi, CANINTF, CANINTF_RX0IF, 0x00);
                }

                /* receive buffer 1 */
                if (intf & CANINTF_RX1IF) {
                        mcp251x_hw_rx(spi, 1);
                        /* The MCP2515/25625 does this automatically. */
                        if (mcp251x_is_2510(spi))
                                clear_intf |= CANINTF_RX1IF;
                }

                /* any error or tx interrupt we need to clear? */
                if (intf & (CANINTF_ERR | CANINTF_TX))
                        clear_intf |= intf & (CANINTF_ERR | CANINTF_TX);
                if (clear_intf)
                        mcp251x_write_bits(spi, CANINTF, clear_intf, 0x00);

                if (eflag & (EFLG_RX0OVR | EFLG_RX1OVR))
                        mcp251x_write_bits(spi, EFLG, eflag, 0x00);

                /* Update can state */
                if (eflag & EFLG_TXBO) {
                        new_state = CAN_STATE_BUS_OFF;
                        can_id |= CAN_ERR_BUSOFF;
                } else if (eflag & EFLG_TXEP) {
                        new_state = CAN_STATE_ERROR_PASSIVE;
                        can_id |= CAN_ERR_CRTL;
                        data1 |= CAN_ERR_CRTL_TX_PASSIVE;
                } else if (eflag & EFLG_RXEP) {
                        new_state = CAN_STATE_ERROR_PASSIVE;
                        can_id |= CAN_ERR_CRTL;
                        data1 |= CAN_ERR_CRTL_RX_PASSIVE;
                } else if (eflag & EFLG_TXWAR) {
                        new_state = CAN_STATE_ERROR_WARNING;
                        can_id |= CAN_ERR_CRTL;
                        data1 |= CAN_ERR_CRTL_TX_WARNING;
                } else if (eflag & EFLG_RXWAR) {
                        new_state = CAN_STATE_ERROR_WARNING;
                        can_id |= CAN_ERR_CRTL;
                        data1 |= CAN_ERR_CRTL_RX_WARNING;
                } else {
                        new_state = CAN_STATE_ERROR_ACTIVE;
                }

                /* Update can state statistics */
                switch (priv->can.state) {
                case CAN_STATE_ERROR_ACTIVE:
                        if (new_state >= CAN_STATE_ERROR_WARNING &&
                            new_state <= CAN_STATE_BUS_OFF)
                                priv->can.can_stats.error_warning++;
                case CAN_STATE_ERROR_WARNING:   /* fallthrough */
                        if (new_state >= CAN_STATE_ERROR_PASSIVE &&
                            new_state <= CAN_STATE_BUS_OFF)
                                priv->can.can_stats.error_passive++;
                        break;
                default:
                        break;
                }
                priv->can.state = new_state;

                if (intf & CANINTF_ERRIF) {
                        /* Handle overflow counters */
                        if (eflag & (EFLG_RX0OVR | EFLG_RX1OVR)) {
                                if (eflag & EFLG_RX0OVR) {
                                        net->stats.rx_over_errors++;
                                        net->stats.rx_errors++;
                                }
                                if (eflag & EFLG_RX1OVR) {
                                        net->stats.rx_over_errors++;
                                        net->stats.rx_errors++;
                                }
                                can_id |= CAN_ERR_CRTL;
                                data1 |= CAN_ERR_CRTL_RX_OVERFLOW;
                        }
                        mcp251x_error_skb(net, can_id, data1);
                }

                if (priv->can.state == CAN_STATE_BUS_OFF) {
                        if (priv->can.restart_ms == 0) {
                                priv->force_quit = 1;
                                priv->can.can_stats.bus_off++;
                                can_bus_off(net);
                                mcp251x_hw_sleep(spi);
                                break;
                        }
                }

                if (intf == 0)
                        break;

                if (intf & CANINTF_TX) {
                        net->stats.tx_packets++;
                        net->stats.tx_bytes += priv->tx_len - 1;
                        can_led_event(net, CAN_LED_EVENT_TX);
                        if (priv->tx_len) {
                                can_get_echo_skb(net, 0);
                                priv->tx_len = 0;
                        }
                        netif_wake_queue(net);
                }

        }
        mutex_unlock(&priv->mcp_lock);
        return IRQ_HANDLED;
}

static int mcp251x_open(struct net_device *net)
{
        struct mcp251x_priv *priv = netdev_priv(net);
        struct spi_device *spi = priv->spi;
        unsigned long flags = IRQF_ONESHOT | IRQF_TRIGGER_FALLING;
        int ret;

        ret = open_candev(net);
        if (ret) {
                dev_err(&spi->dev, "unable to set initial baudrate!\n");
                return ret;
        }

        mutex_lock(&priv->mcp_lock);
        mcp251x_power_enable(priv->transceiver, 1);

        priv->force_quit = 0;
        priv->tx_skb = NULL;
        priv->tx_len = 0;

        ret = request_threaded_irq(spi->irq, NULL, mcp251x_can_ist,
                                   flags | IRQF_ONESHOT, DEVICE_NAME, priv);
        if (ret) {
                dev_err(&spi->dev, "failed to acquire irq %d\n", spi->irq);
                goto out_close;
        }

        priv->wq = alloc_workqueue("mcp251x_wq", WQ_FREEZABLE | WQ_MEM_RECLAIM,
                                   0);
        if (!priv->wq) {
                ret = -ENOMEM;
                goto out_clean;
        }
        INIT_WORK(&priv->tx_work, mcp251x_tx_work_handler);
        INIT_WORK(&priv->restart_work, mcp251x_restart_work_handler);

        ret = mcp251x_hw_reset(spi);
        if (ret)
                goto out_free_wq;
        ret = mcp251x_setup(net, spi);
        if (ret)
                goto out_free_wq;
        ret = mcp251x_set_normal_mode(spi);
        if (ret)
                goto out_free_wq;

        can_led_event(net, CAN_LED_EVENT_OPEN);

        netif_wake_queue(net);
        mutex_unlock(&priv->mcp_lock);

        return 0;

out_free_wq:
        destroy_workqueue(priv->wq);
out_clean:
        free_irq(spi->irq, priv);
        mcp251x_hw_sleep(spi);
out_close:
        mcp251x_power_enable(priv->transceiver, 0);
        close_candev(net);
        mutex_unlock(&priv->mcp_lock);
        return ret;
}

static const struct net_device_ops mcp251x_netdev_ops = {
        .ndo_open = mcp251x_open,
        .ndo_stop = mcp251x_stop,
        .ndo_start_xmit = mcp251x_hard_start_xmit,
        .ndo_change_mtu = can_change_mtu,
};

static const struct of_device_id mcp251x_of_match[] = {
        {
                .compatible     = "microchip,mcp2510",
                .data           = (void *)CAN_MCP251X_MCP2510,
        },
        {
                .compatible     = "microchip,mcp2515",
                .data           = (void *)CAN_MCP251X_MCP2515,
        },
        {
                .compatible     = "microchip,mcp25625",
                .data           = (void *)CAN_MCP251X_MCP25625,
        },
        { }
};
MODULE_DEVICE_TABLE(of, mcp251x_of_match);

static const struct spi_device_id mcp251x_id_table[] = {
        {
                .name           = "mcp2510",
                .driver_data    = (kernel_ulong_t)CAN_MCP251X_MCP2510,
        },
        {
                .name           = "mcp2515",
                .driver_data    = (kernel_ulong_t)CAN_MCP251X_MCP2515,
        },
        {
                .name           = "mcp25625",
                .driver_data    = (kernel_ulong_t)CAN_MCP251X_MCP25625,
        },
        { }
};
MODULE_DEVICE_TABLE(spi, mcp251x_id_table);

static int mcp251x_can_probe(struct spi_device *spi)
{
        const struct of_device_id *of_id = of_match_device(mcp251x_of_match,
                                                           &spi->dev);
        struct mcp251x_platform_data *pdata = dev_get_platdata(&spi->dev);
        struct net_device *net;
        struct mcp251x_priv *priv;
        struct clk *clk;
        int freq, ret;

        clk = devm_clk_get(&spi->dev, NULL);
        if (IS_ERR(clk)) {
                if (pdata)
                        freq = pdata->oscillator_frequency;
                else
                        return PTR_ERR(clk);
        } else {
                freq = clk_get_rate(clk);
        }

        /* Sanity check */
        if (freq < 1000000 || freq > 25000000)
                return -ERANGE;

        /* Allocate can/net device */
        net = alloc_candev(sizeof(struct mcp251x_priv), TX_ECHO_SKB_MAX);
        if (!net)
                return -ENOMEM;

        if (!IS_ERR(clk)) {
                ret = clk_prepare_enable(clk);
                if (ret)
                        goto out_free;
        }

        net->netdev_ops = &mcp251x_netdev_ops;
        net->flags |= IFF_ECHO;

        priv = netdev_priv(net);
        priv->can.bittiming_const = &mcp251x_bittiming_const;
        priv->can.do_set_mode = mcp251x_do_set_mode;
        priv->can.clock.freq = freq / 2;
        priv->can.ctrlmode_supported = CAN_CTRLMODE_3_SAMPLES |
                CAN_CTRLMODE_LOOPBACK | CAN_CTRLMODE_LISTENONLY;
        if (of_id)
                priv->model = (enum mcp251x_model)of_id->data;
        else
                priv->model = spi_get_device_id(spi)->driver_data;
        priv->net = net;
        priv->clk = clk;

        spi_set_drvdata(spi, priv);

        /* Configure the SPI bus */
        spi->bits_per_word = 8;
        if (mcp251x_is_2510(spi))
                spi->max_speed_hz = spi->max_speed_hz ? : 5 * 1000 * 1000;
        else
                spi->max_speed_hz = spi->max_speed_hz ? : 10 * 1000 * 1000;
        ret = spi_setup(spi);
        if (ret)
                goto out_clk;

        priv->power = devm_regulator_get_optional(&spi->dev, "vdd");
        priv->transceiver = devm_regulator_get_optional(&spi->dev, "xceiver");
        if ((PTR_ERR(priv->power) == -EPROBE_DEFER) ||
            (PTR_ERR(priv->transceiver) == -EPROBE_DEFER)) {
                ret = -EPROBE_DEFER;
                goto out_clk;
        }

        ret = mcp251x_power_enable(priv->power, 1);
        if (ret)
                goto out_clk;

        priv->spi = spi;
        mutex_init(&priv->mcp_lock);

        /* If requested, allocate DMA buffers */
        if (mcp251x_enable_dma) {
                spi->dev.coherent_dma_mask = ~0;

                /*
                 * Minimum coherent DMA allocation is PAGE_SIZE, so allocate
                 * that much and share it between Tx and Rx DMA buffers.
                 */
                priv->spi_tx_buf = dmam_alloc_coherent(&spi->dev,
                                                       PAGE_SIZE,
                                                       &priv->spi_tx_dma,
                                                       GFP_DMA);

                if (priv->spi_tx_buf) {
                        priv->spi_rx_buf = (priv->spi_tx_buf + (PAGE_SIZE / 2));
                        priv->spi_rx_dma = (dma_addr_t)(priv->spi_tx_dma +
                                                        (PAGE_SIZE / 2));
                } else {
                        /* Fall back to non-DMA */
                        mcp251x_enable_dma = 0;
                }
        }

        /* Allocate non-DMA buffers */
        if (!mcp251x_enable_dma) {
                priv->spi_tx_buf = devm_kzalloc(&spi->dev, SPI_TRANSFER_BUF_LEN,
                                                GFP_KERNEL);
                if (!priv->spi_tx_buf) {
                        ret = -ENOMEM;
                        goto error_probe;
                }
                priv->spi_rx_buf = devm_kzalloc(&spi->dev, SPI_TRANSFER_BUF_LEN,
                                                GFP_KERNEL);
                if (!priv->spi_rx_buf) {
                        ret = -ENOMEM;
                        goto error_probe;
                }
        }

        SET_NETDEV_DEV(net, &spi->dev);

        /* Here is OK to not lock the MCP, no one knows about it yet */
        ret = mcp251x_hw_probe(spi);
        if (ret) {
                if (ret == -ENODEV)
                        dev_err(&spi->dev, "Cannot initialize MCP%x. Wrong wiring?\n", priv->model);
                goto error_probe;
        }

        mcp251x_hw_sleep(spi);

        ret = register_candev(net);
        if (ret)
                goto error_probe;

        devm_can_led_init(net);

        netdev_info(net, "MCP%x successfully initialized.\n", priv->model);
        return 0;

error_probe:
        mcp251x_power_enable(priv->power, 0);

out_clk:
        if (!IS_ERR(clk))
                clk_disable_unprepare(clk);

out_free:
        free_candev(net);

        dev_err(&spi->dev, "Probe failed, err=%d\n", -ret);
        return ret;
}

static int mcp251x_can_remove(struct spi_device *spi)
{
        struct mcp251x_priv *priv = spi_get_drvdata(spi);
        struct net_device *net = priv->net;

        unregister_candev(net);

        mcp251x_power_enable(priv->power, 0);

        if (!IS_ERR(priv->clk))
                clk_disable_unprepare(priv->clk);

        free_candev(net);

        return 0;
}

static int __maybe_unused mcp251x_can_suspend(struct device *dev)
{
        struct spi_device *spi = to_spi_device(dev);
        struct mcp251x_priv *priv = spi_get_drvdata(spi);
        struct net_device *net = priv->net;

        priv->force_quit = 1;
        disable_irq(spi->irq);
        /*
         * Note: at this point neither IST nor workqueues are running.
         * open/stop cannot be called anyway so locking is not needed
         */
        if (netif_running(net)) {
                netif_device_detach(net);

                mcp251x_hw_sleep(spi);
                mcp251x_power_enable(priv->transceiver, 0);
                priv->after_suspend = AFTER_SUSPEND_UP;
        } else {
                priv->after_suspend = AFTER_SUSPEND_DOWN;
        }

        if (!IS_ERR_OR_NULL(priv->power)) {
                regulator_disable(priv->power);
                priv->after_suspend |= AFTER_SUSPEND_POWER;
        }

        return 0;
}

static int __maybe_unused mcp251x_can_resume(struct device *dev)
{
        struct spi_device *spi = to_spi_device(dev);
        struct mcp251x_priv *priv = spi_get_drvdata(spi);

        if (priv->after_suspend & AFTER_SUSPEND_POWER)
                mcp251x_power_enable(priv->power, 1);

        if (priv->after_suspend & AFTER_SUSPEND_UP) {
                mcp251x_power_enable(priv->transceiver, 1);
                queue_work(priv->wq, &priv->restart_work);
        } else {
                priv->after_suspend = 0;
        }

        priv->force_quit = 0;
        enable_irq(spi->irq);
        return 0;
}

static SIMPLE_DEV_PM_OPS(mcp251x_can_pm_ops, mcp251x_can_suspend,
        mcp251x_can_resume);

static struct spi_driver mcp251x_can_driver = {
        .driver = {
                .name = DEVICE_NAME,
                .of_match_table = mcp251x_of_match,
                .pm = &mcp251x_can_pm_ops,
        },
        .id_table = mcp251x_id_table,
        .probe = mcp251x_can_probe,
        .remove = mcp251x_can_remove,
};
module_spi_driver(mcp251x_can_driver);

MODULE_AUTHOR("Chris Elston <celston@katalix.com>, "
              "Christian Pellegrin <chripell@evolware.org>");
MODULE_DESCRIPTION("Microchip 251x/25625 CAN driver");
MODULE_LICENSE("GPL v2");