can3--socketcan之mcp251x.c

2016-12-14 09:56:34来源:http://blog.csdn.net/songqqnew/article/details/7599725作者:songqqnew人点击

函数原型源于2.6.38
******************************************************************
spi驱动结构见
http://blog.csdn.net/songqqnew/article/details/7037583
mcp251x.c和dm9000.c驱动模式类似
参考


dm9000 driver 1


理清一下驱动的线索
******************************************************************
在init函数中注册spi驱动mcp251x_can_driver
static int __init mcp251x_can_init(void)
{
DBG("init/n");
return spi_register_driver(&mcp251x_can_driver);
}
在spi驱动mcp251x_can_driver的probe函数中分配net_device
static struct spi_driver mcp251x_can_driver = {
.driver = {
.name = DEVICE_NAME,//mcp2515
.bus = &spi_bus_type,
.owner = THIS_MODULE,
}, .id_table = mcp251x_id_table,
.probe = mcp251x_can_probe,//probe
.remove = __devexit_p(mcp251x_can_remove),
.suspend = mcp251x_can_suspend,
.resume = mcp251x_can_resume,
};
static int __devinit mcp251x_can_probe(struct spi_device *spi)
{
net = alloc_candev(sizeof(struct mcp251x_priv), TX_ECHO_SKB_MAX);
if (!net) {
ret = -ENOMEM;
goto error_alloc;
}
//注册net_device
register_candev(net);
//net_device的operation结构体指定了操作函数集合
static const struct net_device_ops mcp251x_netdev_ops = {
.ndo_open = mcp251x_open,
.ndo_stop = mcp251x_stop,
.ndo_start_xmit = mcp251x_hard_start_xmit,
};
}

应用层执行ifconfig can0 up时会调用到mcp251x_openmcp251x_open函数中,
//打开设备
open_candev(net);
//申请中断
ret = request_irq(spi->irq, mcp251x_can_irq, /*IRQF_DISABLED |*/ IRQF_TRIGGER_LOW , DEVICE_NAME, priv);
//初始化工作队列,当做中断(接收)下半部,用于处理接收
INIT_WORK(&priv->irq_work,can_irq_work);
//初始化工作队列,用于处理发送
INIT_WORK(&priv->tx_work, mcp251x_tx_work_handler);

应用层执行write socket时会调用到
mcp251x_hard_start_xmit,
mcp251x_hard_start_xmit函数中,
//停止协议栈向驱动发送数据(在发送数据的时候需要停止协议栈发来新的需要发送出去的数据),发送完成后会重新启用
netif_stop_queue(net);
//启动发送工作队列,将数据(skb)发送出去
priv->tx_skb = skb;
queue_work(priv->wq, &priv->tx_work);

具体看一下这个发送工作队列函数
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;
// printk("mcp251x_tx_work_handler/n");
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);
}

怎么接收呢?当然是在中断处理函数中接收,有中断产生时,会启用一个负责接受的工作队列,即中断下半部,去接收。并将接收到的数据保存,以供应用层使用read socket等来读取。
static irqreturn_t mcp251x_can_irq(int irq, void *dev_id)
{
DBG("zhongduan :mcp251x_can_irq/n");
struct mcp251x_priv *priv = dev_id;
disable_irq_nosync(irq);//禁止中断,工作队列函数中接收完成时会重新使能中断
if (!work_pending(&priv->irq_work))
queue_work(priv->wq, &priv->irq_work);//调用工作队列函数
return IRQ_HANDLED;
}

接收工作队列函数
void can_irq_work(struct work_struct *ws)
{
DBG("zhongduan bottom: can_irq_work/n");
struct mcp251x_priv *priv = container_of(ws, struct mcp251x_priv,
irq_work);
struct spi_device *spi = priv->spi;
struct net_device *net = priv->net;
mutex_lock(&priv->mcp_lock);
//mcp251x_write_reg(spi, CANINTE, (intset & (~ ( CANINTE_TX2IE) )));
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);
DBG("intf=%x/n",intf);//一般返回1,表示rxb0里有数据。
//mcp251x_write_bits(spi, CANINTF, intf, 0x00);
/* mask out flags we don't care about */
intf &= CANINTF_RX | CANINTF_TX | CANINTF_ERR ;//| CANINTF_MERRF;
if (intf & CANINTF_TX) {//如果是发送完成中断
net->stats.tx_packets++;
net->stats.tx_bytes += priv->tx_len - 1;
if (priv->tx_len) {
can_get_echo_skb(net, 0);
priv->tx_len = 0;
}
netif_wake_queue(net);//重新开启
}

/* receive buffer 1 */
if (intf & CANINTF_RX1IF) {//如果是从mcp251x的buffer 1接收到数据的中断
mcp251x_hw_rx(spi, 1);//接收
/* the MCP2515 does this automatically */
if (mcp251x_is_2510(spi))
clear_intf |= CANINTF_RX1IF;//清除mcp251x里的中断标志
}
/* receive buffer 0 */
if (intf & CANINTF_RX0IF) {//如果是从mcp251x的buffer 0接收到数据的中断
mcp251x_hw_rx(spi, 0);//接收mcp2515的rxb0里的数据,见下
/*
* Free one buffer ASAP
* (The MCP2515 does this automatically.)
*/
if (mcp251x_is_2510(spi))
mcp251x_write_bits(spi, CANINTF, CANINTF_RX0IF, 0x00);//清除mcp251x里的中断标志
}
/* 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)
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;
can_bus_off(net);
mcp251x_hw_sleep(spi);
break;
}
}
if (intf == 0)
break;

}
//mcp251x_write_reg(spi, CANINTE, intset);
mutex_unlock(&priv->mcp_lock); enable_irq(spi->irq);//重新使能中断
//s3c_gpio_cfgpin(S3C64XX_GPL(8), S3C_GPIO_SFN(3)); }
附mcp251x.c源码
/*
 * CAN bus driver for Microchip 251x CAN Controller with SPI Interface
 *
 * MCP2510 support and bug fixes by Christian Pellegrin
 *
 *
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *
 *
 * Your platform definition file should specify something like:
 *
 * static struct mcp251x_platform_data mcp251x_info = {
 *         .oscillator_frequency = 8000000,
 *         .board_specific_setup = &mcp251x_setup,
 *         .power_enable = mcp251x_power_enable,
 *         .transceiver_enable = NULL,
 * };
 *
 * static struct spi_board_info spi_board_info[] = {
 *         {
 *                 .modalias = "mcp2510",
 *            // or "mcp2515" 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.
 *
 */#define DEBUG  
#ifdef DEBUG    
#define DBG(...) printk(" DBG(%s, %s(), %d): ", __FILE__, __FUNCTION__, __LINE__); printk(__VA_ARGS__)    
#else    
#define DBG(...)    
#endif    
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include #include
#include
/* 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
/* 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 RXFSIDH(n) ((n) * 4)
#define RXFSIDL(n) ((n) * 4 + 1)
#define RXFEID8(n) ((n) * 4 + 2)
#define RXFEID0(n) ((n) * 4 + 3)
#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 DEVICE_NAME "mcp2515"//static struct timer_list check_timer;
void can_irq_work(struct work_struct *ws);
//static struct work_struct can_work;
static int intset;//中断设置static int mcp251x_enable_dma; /* Enable SPI DMA. Default: 0 (Off) */
module_param(mcp251x_enable_dma, int, S_IRUGO);
MODULE_PARM_DESC(mcp251x_enable_dma, "Enable SPI DMA. Default: 0 (Off)");
static 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,
};
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;
        struct work_struct irq_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;
};
#define MCP251X_IS(_model) /
static inline int mcp251x_is_##_model(struct spi_device *spi) /
{ /
    struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev); /
    return priv->model == CAN_MCP251X_MCP##_model; /
}
MCP251X_IS(2510);
MCP251X_IS(2515);
static void mcp251x_clean(struct net_device *net)
{
    struct mcp251x_priv *priv = netdev_priv(net);
//    DBG("mcp251x_clean/n");
    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 = dev_get_drvdata(&spi->dev);
    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;
//    DBG("mcp251x_spi_trans/n");
    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);
        //ret= spi_async (spi,&m);
    if (ret)
        dev_err(&spi->dev, "spi transfer failed: ret = %d/n", ret);
       
    int i=0;
DBG("打印spi直接发送的数据/n");
for( i=0;i{
DBG("priv->spi_tx_buf[%d]=%x/n",i,priv->spi_tx_buf[i]);
}
DBG("打印spi直接收到的数据/n");
for( i=0;i{
DBG("priv->spi_rx_buf[%d]=%x/n",i,priv->spi_rx_buf[i]);
}
    return ret;
}
static u8 mcp251x_read_reg(struct spi_device *spi, uint8_t reg)
{
    struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
    u8 val = 0;//INSTRUCTION_READ=3
//根据mcp2515手册p64,使用spi接口读取寄存器的步骤是发送 命令03+地址
//接收到的寄存器数据在spi_rx_buf[2]
    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 = dev_get_drvdata(&spi->dev);
    priv->spi_tx_buf[0] = INSTRUCTION_READ;
    priv->spi_tx_buf[1] = reg;
    mcp251x_spi_trans(spi, 4);
////接收到的寄存器数据在spi_rx_buf[2],spi_rx_buf[3]
    *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 = dev_get_drvdata(&spi->dev);
 
//INSTRUCTION_WRITE=2
//根据mcp2515手册p64,使用spi接口写寄存器的步骤是发送 命令02+地址+值
    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 = dev_get_drvdata(&spi->dev);
//INSTRUCTION_BIT_MODIFY=5
//位修改指令,对可执行位操作的寄存器有效
    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 = dev_get_drvdata(&spi->dev);
//如果是2510,还需要指定使用那个发送缓冲区发送数据
//
    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)
{
    u32 sid, eid, exide, rtr;
    u8 buf[SPI_TRANSFER_BUF_LEN];
    exide = (frame->can_id & CAN_EFF_FLAG) ? 1 : 0; /* Extended ID Enable */
DBG("打印是否扩展帧/n");
    if (exide)
        {
        sid = (frame->can_id & CAN_EFF_MASK) >> 18;
        DBG("是扩展帧/n");
        }
    else
        {
        sid = frame->can_id & CAN_SFF_MASK; /* Standard ID */
        DBG("是标准帧/n");
        }
    eid = frame->can_id & CAN_EFF_MASK; /* Extended ID */
    rtr = (frame->can_id & CAN_RTR_FLAG) ? 1 : 0; /* Remote transmission */
//INSTRUCTION_LOAD_TXB(0)=0x40,即装载tx0缓冲器
    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);
int i;
DBG("打印送给spi的数据/n");
for(i=0;i{
DBG("buf[%d]=%x/n",i,buf[i]);
}
    mcp251x_hw_tx_frame(spi, buf, frame->can_dlc, tx_buf_idx);//装载到tx0缓冲器
    mcp251x_write_reg(spi, TXBCTRL(tx_buf_idx), TXBCTRL_TXREQ);//请求发送tx0
}
static void mcp251x_hw_rx_frame(struct spi_device *spi, u8 *buf,
                int buf_idx)
{
    struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
//        DBG("mcp251x_hw_rx_frame/n");
DBG("打印是否是mcp2515/n");
    if (mcp251x_is_2510(spi)) {
DBG("是mcp2510/n");
        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 {
DBG("是mcp2515/n");
//INSTRUCTION_READ_RXB(0)=90,即读取rx0缓冲器
        priv->spi_tx_buf[RXBCTRL_OFF] = INSTRUCTION_READ_RXB(buf_idx);
/*SPI_TRANSFER_BUF_LEN=14,
即spi的发送和接收缓冲区都设为14
因为mcp2515共返回14个字节,假如是读rxbuf0,则
RXBOCTRL
RXB0SIDH
RXB0SIDL
RXB0EID8
RXB0EID0
RXB0DLC
RXB0D0
...
RXB0D7
*/
        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 = dev_get_drvdata(&spi->dev);
    struct sk_buff *skb;
    struct can_frame *frame;
    u8 buf[SPI_TRANSFER_BUF_LEN];
//    DBG("mcp251x_hw_rx/n");
    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);// 接收数据
DBG("打印从spi接收到buf里的数据/n");
    DBG(" buf_idx=%d/n",buf_idx);
    int i;
    for(i=0;i    {
    DBG(" buf[%d]=%x/n",i,buf[i]);
    }
DBG("打印是否是扩展帧/n");
    if (buf[RXBSIDL_OFF] & RXBSIDL_IDE) {
//buf[RXBSIDL_OFF]即buf[2]即寄存器RXBnSIDL的第4位表示是否是扩展帧
DBG("是扩展帧/n");
        /* 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 {
DBG("是标准帧/n");
        /* Standard ID format */
//RXBSIDH的全8位和RXBSIDL的高3位即11位共同组成标准帧的标识符,详见mcp2515手册,
//所以理论上一条can总线最多可分辨2048个设备(扩展帧也是11位标识符)
//如果
//buf[1]=寄存器RXBSIDH=0x24=0010 0100,<<3=0010 0100 000
//buf[2]=寄存器RXBSIDL=0x60=0110 0000,>>5=011
//加上之后=001 0010 0011=0x123
        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 */
//buf[3]=寄存器RXBEID8,标准帧不使用
//buf[4]=寄存器RXBEID0,标准帧不使用
//buf[5]=寄存器RXBDLC=数据段长度
    frame->can_dlc = get_can_dlc(buf[RXBDLC_OFF] & RXBDLC_LEN_MASK);
//buf[6]-buf[13]=8个数据寄存器RXB0D0-RXB0D7
    memcpy(frame->data, buf + RXBDAT_OFF, frame->can_dlc);
DBG("打印can_frame的字段/n");
DBG(" frame->can_id=0x%x/n", frame->can_id);
char *p=(char*)&(frame->can_id);
for(i=0;i<4;i++)
{
DBG(" p=%x/n",*p);
p++;
}
DBG(" frame->can_dlc=%d/n", frame->can_dlc);
for(i=0;i<8;i++)
{
DBG(" frame->data[%d]=%x/n",i,frame->data[i]);
}
    priv->net->stats.rx_packets++;
    priv->net->stats.rx_bytes += frame->can_dlc;
DBG("打印skb里的数据/n");
for(i=0;i<20;i++)
{
DBG("skb->data[%d]=%x/n",i,skb->data[i]);
}
    netif_rx_ni(skb);
}
static void mcp251x_hw_sleep(struct spi_device *spi)
{
//    DBG("mcp251x_hw_sleep/n");
    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;
DBG("从应用层收到发送命令/n");
    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;
DBG("要发送的数据是skb/n");
DBG("启动发送队列/n");
    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);
         
//        DBG("mcp251x_do_set_mode/n");
    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 = dev_get_drvdata(&spi->dev);
    unsigned long timeout;
//     DBG("mcp251x_set_normal_mode/n");
    /* Enable interrupts */
        intset=CANINTE_ERRIE | CANINTE_TX2IE | CANINTE_TX1IE | //CANINTF_MERRF |
              CANINTE_TX0IE | CANINTE_RX1IE | CANINTE_RX0IE;
    mcp251x_write_reg(spi, CANINTE,intset);    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;
//    DBG("mcp251x_do_set_bittiming/n");
    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_info(&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 mcp251x_priv *priv,
             struct spi_device *spi)
{
    mcp251x_do_set_bittiming(net);
//    DBG("mcp251x_setup/n");
    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 = dev_get_drvdata(&spi->dev);
    int ret;
    unsigned long timeout;
//    DBG("mcp251x_hw_reset/n");
    priv->spi_tx_buf[0] = INSTRUCTION_RESET;
    ret = spi_write(spi, priv->spi_tx_buf, 1);
    if (ret) {
        dev_err(&spi->dev, "reset failed: ret = %d/n", ret);
        return -EIO;
    }
    /* Wait for reset to finish */
    timeout = jiffies + HZ;
    mdelay(10);
    while ((mcp251x_read_reg(spi, CANSTAT) & CANCTRL_REQOP_MASK)
           != CANCTRL_REQOP_CONF) {
        schedule();
        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)
{
    int st1, st2;
//    DBG("mcp251x_hw_probe/n");
    mcp251x_hw_reset(spi);
    /*
     * Please note that these are "magic values" based on after
     * reset defaults taken from data sheet which allows us to see
     * if we really have a chip on the bus (we avoid common all
     * zeroes or all ones situations)
     */
    st1 = mcp251x_read_reg(spi, CANSTAT) & 0xEE;
    st2 = mcp251x_read_reg(spi, CANCTRL) & 0x17;
    dev_dbg(&spi->dev, "CANSTAT 0x%02x CANCTRL 0x%02x/n", st1, st2);
    /* Check for power up default values */
    return (st1 == 0x80 && st2 == 0x07) ? 1 : 0;
}
static void mcp251x_open_clean(struct net_device *net)
{
    struct mcp251x_priv *priv = netdev_priv(net);
    struct spi_device *spi = priv->spi;
    struct mcp251x_platform_data *pdata = spi->dev.platform_data;
        DBG("mcp251x_open_clean/n");
    free_irq(spi->irq, priv);
    mcp251x_hw_sleep(spi);
    if (pdata->transceiver_enable)
        pdata->transceiver_enable(0);
    close_candev(net);
}
static int mcp251x_stop(struct net_device *net)
{
    struct mcp251x_priv *priv = netdev_priv(net);
    struct spi_device *spi = priv->spi;
    struct mcp251x_platform_data *pdata = spi->dev.platform_data;
     DBG("mcp251x_stop/n");
    close_candev(net);
    priv->force_quit = 1;
      
    free_irq(spi->irq, priv);
    destroy_workqueue(priv->wq);
    priv->wq = NULL;
//        del_timer(&check_timer);  //删除定时器
    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);
    if (pdata->transceiver_enable)
        pdata->transceiver_enable(0);
    priv->can.state = CAN_STATE_STOPPED;
    mutex_unlock(&priv->mcp_lock);
    return 0;
}
static void mcp251x_error_skb(struct net_device *net, int can_id, int data1)
{
    struct sk_buff *skb;
    struct can_frame *frame;
     DBG("mcp251x_error_skb/n");
    skb = alloc_can_err_skb(net, &frame);
    if (skb) {
        frame->can_id |= can_id;
        frame->data[1] = data1;
        netif_rx_ni(skb);
    } else {
        dev_err(&net->dev,
            "cannot allocate error skb/n");
    }
}
static void mcp251x_tx_work_handler(struct work_struct *ws)
{
DBG("进入发送队列/n");
    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 {
int i;
DBG("打印skb里的数据/n");
for(i=0;i<20;i++)
{
DBG("priv->tx_skb->data[%d]=%x/n",i,priv->tx_skb->data[i]);
}
//将skb里的数据给can_frame以便组织发送
            frame = (struct can_frame *)priv->tx_skb->data;
DBG("打印can_frame的字段/n");
DBG(" frame->can_id=0x%x/n", frame->can_id);
char *p=(char*)&(frame->can_id);
for(i=0;i<4;i++)
{
DBG(" p=%x/n",*p);
p++;
}
DBG(" frame->can_dlc=%d/n", frame->can_dlc);
for(i=0;i<8;i++)
{
DBG(" frame->data[%d]=%x/n",i,frame->data[i]);
}
            if (frame->can_dlc > CAN_FRAME_MAX_DATA_LEN)
                frame->can_dlc = CAN_FRAME_MAX_DATA_LEN;
//发送
            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;
    DBG("mcp251x_restart_work_handler/n");
    mutex_lock(&priv->mcp_lock);
    if (priv->after_suspend) {
        mdelay(10);
        mcp251x_hw_reset(spi);
        mcp251x_setup(net, priv, spi);
        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;
        priv->force_quit = 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 void check_timer_callback(unsigned long arg)
{
    //DBG("timer clean CANINTF %X/n",arg);
    //int pin=gpio_get_value(S3C64XX_GPL(8));
 //   int pin=gpio_get_value(S3C64XX_GPN(5));
    int pin=gpio_get_value(S3C64XX_GPL(8));
//    DBG("timer pin=%d /n",pin);
    if(pin==0)
    {
//        struct mcp251x_priv *priv=(struct mcp251x_priv *)arg;
//        schedule_work(&(priv->irq_work));        DBG("timer schedule work/n");
    }
    mod_timer(&check_timer,jiffies+8);        //修改定时器
}*/static irqreturn_t mcp251x_can_irq(int irq, void *dev_id)
{
DBG("有中断产生/n");
       struct mcp251x_priv *priv = dev_id;
//       struct spi_device *spi = priv->spi;
      // int pin=gpio_get_value(S3C64XX_GPL(8));
      // DBG("pin=%d /n",pin);
 
//DBG("before disable_irq_nosync(irq);/n");
        disable_irq_nosync(irq);
    //disable_irq(irq);
//DBG("after disable_irq_nosync(irq);/n");
       //s3c_gpio_cfgpin(S3C64XX_GPL(8), S3C_GPIO_INPUT);  //关中断,为什么disable_irq死机
       //while(S3C_GPIO_INPUT!=s3c_gpio_getcfg(S3C64XX_GPL(8)));
       //schedule_work(&(priv->irq_work));       if (!work_pending(&priv->irq_work))
        queue_work(priv->wq, &priv->irq_work);
      
    //enable_irq(irq);
       return IRQ_HANDLED;
}
/*
static irqreturn_t mcp251x_can_irq(int irq, void *dev_id)
{
DBG("mcp251x_can_irq/n");
       struct mcp251x_priv *priv = dev_id;
//       struct spi_device *spi = priv->spi;
      // int pin=gpio_get_value(S3C64XX_GPL(8));
      // DBG("pin=%d /n",pin);
 
        //disable_irq_nosync(irq);
       s3c_gpio_cfgpin(S3C64XX_GPL(8), S3C_GPIO_INPUT);  //关中断,为什么disable_irq死机
       while(S3C_GPIO_INPUT!=s3c_gpio_getcfg(S3C64XX_GPL(8)));
       //schedule_work(&(priv->irq_work));       if (!work_pending(&priv->irq_work))
        queue_work(priv->wq, &priv->irq_work);
      
       return IRQ_HANDLED;
}
*/void can_irq_work(struct work_struct *ws)
{
DBG("进入中断下半部/n");
     struct mcp251x_priv *priv = container_of(ws, struct mcp251x_priv,
                         irq_work);
     struct spi_device *spi = priv->spi;
     struct net_device *net = priv->net;
    mutex_lock(&priv->mcp_lock);
        //mcp251x_write_reg(spi, CANINTE, (intset & (~ ( CANINTE_TX2IE) )));
    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);
//读取中断标志寄存器,用于判断是什么中断
                DBG("中断标志=0x%x/n",intf);
                //mcp251x_write_bits(spi, CANINTF, intf, 0x00);
        
        /* mask out flags we don't care about */
        intf &= CANINTF_RX | CANINTF_TX | CANINTF_ERR ;//| CANINTF_MERRF;
                if (intf & CANINTF_TX) {
DBG("是发送完成中断: /n");
            net->stats.tx_packets++;
            net->stats.tx_bytes += priv->tx_len - 1;
            if (priv->tx_len) {
                can_get_echo_skb(net, 0);
                priv->tx_len = 0;
            }
            netif_wake_queue(net);
        }
        
        /* receive buffer 1 */
        if (intf & CANINTF_RX1IF) {
DBG("是接收到数据中断: /n");
DBG("receive buffer1有数据/n");
            mcp251x_hw_rx(spi, 1);
            /* the MCP2515 does this automatically */
            if (mcp251x_is_2510(spi))
                clear_intf |= CANINTF_RX1IF;
        }
                /* receive buffer 0 */
        if (intf & CANINTF_RX0IF) {
DBG("是接收到数据中断: /n");
DBG("receive buffer0有数据/n");
            mcp251x_hw_rx(spi, 0);
            /*
             * Free one buffer ASAP
             * (The MCP2515 does this automatically.)
             */
            if (mcp251x_is_2510(spi))
                mcp251x_write_bits(spi, CANINTF, CANINTF_RX0IF, 0x00);
        }
   
        /* 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)
            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;
                can_bus_off(net);
                mcp251x_hw_sleep(spi);
                break;
            }
        }
                if (intf == 0)
            break;
    
    }
        //mcp251x_write_reg(spi, CANINTE, intset);
    mutex_unlock(&priv->mcp_lock);  
        enable_irq(spi->irq);
        //s3c_gpio_cfgpin(S3C64XX_GPL(8), S3C_GPIO_SFN(3));    //开中断}
static int mcp251x_open(struct net_device *net)
{
    struct mcp251x_priv *priv = netdev_priv(net);
    struct spi_device *spi = priv->spi;
    struct mcp251x_platform_data *pdata = spi->dev.platform_data;
    int ret;
 //       DBG("mcp251x_open/n");
DBG("mcp251x_open");
    ret = open_candev(net);
    if (ret) {
        dev_err(&spi->dev, "unable to set initial baudrate!/n");
        return ret;
    }
    mutex_lock(&priv->mcp_lock);
    if (pdata->transceiver_enable)
        pdata->transceiver_enable(1);
    priv->force_quit = 0;
    priv->tx_skb = NULL;
    priv->tx_len = 0;
/*    ret = request_threaded_irq(spi->irq, NULL, mcp251x_can_ist,
          pdata->irq_flags ? pdata->irq_flags : IRQF_TRIGGER_FALLING, //IRQF_TRIGGER_LOW,  //          DEVICE_NAME, priv);*/
    ret = request_irq(spi->irq, mcp251x_can_irq,
              //IRQF_TRIGGER_FALLING,
                          /*IRQF_DISABLED |*/ IRQF_TRIGGER_LOW , //note by song
              DEVICE_NAME, priv);
    INIT_WORK(&priv->irq_work,can_irq_work);    if (ret) {
        dev_err(&spi->dev, "failed to acquire irq %d/n", spi->irq);
        if (pdata->transceiver_enable)
            pdata->transceiver_enable(0);
        close_candev(net);
        goto open_unlock;
    }
//    init_timer(&check_timer);   //初始化定时器
//        check_timer.expires=jiffies+HZ;
//        check_timer.function=&check_timer_callback;
//        check_timer.data=(long)priv;
        //add_timer(&check_timer);        //添加定时器*/
    priv->wq = create_freezable_workqueue("mcp251x_wq");
        //priv->wq = create_freezeable_workqueue("mcp251x_wq");
    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) {
        mcp251x_open_clean(net);
        goto open_unlock;
    }
    ret = mcp251x_setup(net, priv, spi);
    if (ret) {
        mcp251x_open_clean(net);
        goto open_unlock;
    }
    ret = mcp251x_set_normal_mode(spi);
    if (ret) {
        mcp251x_open_clean(net);
        goto open_unlock;
    }
    netif_wake_queue(net);
open_unlock:
    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,
};
static int __devinit mcp251x_can_probe(struct spi_device *spi)
{
    struct net_device *net;
    struct mcp251x_priv *priv;
    struct mcp251x_platform_data *pdata = spi->dev.platform_data;
    int ret = -ENODEV;
    DBG("@@@@@@@@@@@@@@@@@@@@/n");
    DBG("mcp251x_can_probe /n");
    DBG("@@@@@@@@@@@@@@@@@@@@/n");
    if (!pdata)
        /* Platform data is required for osc freq */
        goto error_out;
    /* Allocate can/net device */
    net = alloc_candev(sizeof(struct mcp251x_priv), TX_ECHO_SKB_MAX);
    if (!net) {
        ret = -ENOMEM;
        goto error_alloc;
    }
    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 = pdata->oscillator_frequency / 2;
    priv->can.ctrlmode_supported = CAN_CTRLMODE_3_SAMPLES |
        CAN_CTRLMODE_LOOPBACK | CAN_CTRLMODE_LISTENONLY;
    priv->model = spi_get_device_id(spi)->driver_data;
    priv->net = net;
    dev_set_drvdata(&spi->dev, priv);
    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 = dma_alloc_coherent(&spi->dev,
                              PAGE_SIZE,
                              &priv->spi_tx_dma,
                              GFP_DMA);
        if (priv->spi_tx_buf) {
            priv->spi_rx_buf = (u8 *)(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 = kmalloc(SPI_TRANSFER_BUF_LEN, GFP_KERNEL);
        if (!priv->spi_tx_buf) {
            ret = -ENOMEM;
            goto error_tx_buf;
        }
        priv->spi_rx_buf = kmalloc(SPI_TRANSFER_BUF_LEN, GFP_KERNEL);
        if (!priv->spi_rx_buf) {
            ret = -ENOMEM;
            goto error_rx_buf;
        }
    }
    if (pdata->power_enable)
        pdata->power_enable(1);
    /* Call out to platform specific setup */
    if (pdata->board_specific_setup)
        pdata->board_specific_setup(spi);
    SET_NETDEV_DEV(net, &spi->dev);
    /* Configure the SPI bus */
    spi->mode = SPI_MODE_0;
    spi->bits_per_word = 8;
    spi_setup(spi);
    /* Here is OK to not lock the MCP, no one knows about it yet */
    if (!mcp251x_hw_probe(spi)) {
        dev_info(&spi->dev, "Probe failed/n");
        goto error_probe;
    }
    mcp251x_hw_sleep(spi);
    if (pdata->transceiver_enable)
        pdata->transceiver_enable(0);
    ret = register_candev(net);
    DBG("@@@@@@@@@@@@@@@@@@@@/n");
    DBG("register_candev ret = %d/n",ret);
    DBG("@@@@@@@@@@@@@@@@@@@@/n");
    if (!ret) {
        dev_info(&spi->dev, "probed/n");
        return ret;
    }
error_probe:
    if (!mcp251x_enable_dma)
        kfree(priv->spi_rx_buf);
error_rx_buf:
    if (!mcp251x_enable_dma)
        kfree(priv->spi_tx_buf);
error_tx_buf:
    free_candev(net);
    if (mcp251x_enable_dma)
        dma_free_coherent(&spi->dev, PAGE_SIZE,
                  priv->spi_tx_buf, priv->spi_tx_dma);
error_alloc:
    if (pdata->power_enable)
        pdata->power_enable(0);
    dev_err(&spi->dev, "probe failed/n");
error_out:
    return ret;
}
static int __devexit mcp251x_can_remove(struct spi_device *spi)
{
    struct mcp251x_platform_data *pdata = spi->dev.platform_data;
    struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
    struct net_device *net = priv->net;
    DBG("mcp251x_can_remove/n");
    unregister_candev(net);
    free_candev(net);
    if (mcp251x_enable_dma) {
        dma_free_coherent(&spi->dev, PAGE_SIZE,
                  priv->spi_tx_buf, priv->spi_tx_dma);
    } else {
        kfree(priv->spi_tx_buf);
        kfree(priv->spi_rx_buf);
    }
    if (pdata->power_enable)
        pdata->power_enable(0);
    return 0;
}
#ifdef CONFIG_PM
static int mcp251x_can_suspend(struct spi_device *spi, pm_message_t state)
{
    struct mcp251x_platform_data *pdata = spi->dev.platform_data;
    struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
    struct net_device *net = priv->net;
    DBG("mcp251x_can_suspend/n");
    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);
        if (pdata->transceiver_enable)
            pdata->transceiver_enable(0);
        priv->after_suspend = AFTER_SUSPEND_UP;
    } else {
        priv->after_suspend = AFTER_SUSPEND_DOWN;
    }
    if (pdata->power_enable) {
        pdata->power_enable(0);
        priv->after_suspend |= AFTER_SUSPEND_POWER;
    }
    return 0;
}
static int mcp251x_can_resume(struct spi_device *spi)
{
        DBG("mcp251x_can_resume/n");
    struct mcp251x_platform_data *pdata = spi->dev.platform_data;
    struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
    if (priv->after_suspend & AFTER_SUSPEND_POWER) {
        pdata->power_enable(1);
        queue_work(priv->wq, &priv->restart_work);
    } else {
        if (priv->after_suspend & AFTER_SUSPEND_UP) {
            if (pdata->transceiver_enable)
                pdata->transceiver_enable(1);
            queue_work(priv->wq, &priv->restart_work);
        } else {
            priv->after_suspend = 0;
        }
    }
    priv->force_quit = 0;
    enable_irq(spi->irq);
    return 0;
}
#else
#define mcp251x_can_suspend NULL
#define mcp251x_can_resume NULL
#endif
static const struct spi_device_id mcp251x_id_table[] = {
    { "mcp2510",    CAN_MCP251X_MCP2510 },
    { "mcp2515",    CAN_MCP251X_MCP2515 },
    { },
};
MODULE_DEVICE_TABLE(spi, mcp251x_id_table);
static struct spi_driver mcp251x_can_driver = {
    .driver = {
        .name = DEVICE_NAME,
        .bus = &spi_bus_type,
        .owner = THIS_MODULE,
    },
    .id_table = mcp251x_id_table,
    .probe = mcp251x_can_probe,
    .remove = __devexit_p(mcp251x_can_remove),
    .suspend = mcp251x_can_suspend,
    .resume = mcp251x_can_resume,
};
static int __init mcp251x_can_init(void)
{
DBG("init/n");
    return spi_register_driver(&mcp251x_can_driver);
}
static void __exit mcp251x_can_exit(void)
{
DBG("exit/n");
    spi_unregister_driver(&mcp251x_can_driver);
}
module_init(mcp251x_can_init);
module_exit(mcp251x_can_exit);
MODULE_AUTHOR("Chris Elston , "
          "Christian Pellegrin ");
MODULE_DESCRIPTION("Microchip 251x CAN driver");
MODULE_LICENSE("GPL v2");

******************************************************************
几个疑点分析----以下讨论适用于te6410
中断注册
static inline int __must_check
request_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,
const char *name, void *dev)
{
return request_threaded_irq(irq, handler, NULL, flags, name, dev);
}
原来他调用了request_threaded_irq(),并将中断处理函数(上半部)handler作为参数传递过去。追踪到request_threaded_irq,如下
int request_threaded_irq(unsigned int irq, irq_handler_t handler,
irq_handler_t thread_fn, unsigned long irqflags,
const char *devname, void *dev_id)
其中要注意的两个参数,
irq_handler_t handler,中断处理函数上半部
irq_handler_t thread_fn,中断线程化,这样直接实现了中断处理函数的下半部,不必自己再去使用工作队列实现下半部了
/*
附工作队列的实现
创建工作队列,并加入到一个工作者线程里让其去执行。这个工作者线程可以使内核现成的,也可以使自己心创建的。
创建一个工作队列work_struct,使用DECLARE_WORK静态创建一个工作队列,参数包括队列名称和队列函数,也可使用INIT_WORK动态创建。
创建一个新的工作者线程workqueue_struct,使用create_workqueue,返回值是工作者线程指针。
将工作队列放到指定的工作者线程中去执行,
int queue_work(struct workqueue_struct *wq, struct work_struct *work)
将工作队列放到系统已有的events工作者线程中去执行,直接调用sheldule_work(&work)即可。

工作者线程是一个内核线程,运行在进程上下文。
工作者线程被唤醒时,会依次执行它里面的工作队列----组成了一个链表。
*/

搜索2.6.32.2源码,只发现一个同时使用了这两个参数的例子Broadcom B43 wireless driver,位于dribers/net/wireless/b43/main.c
		err = request_threaded_irq(dev->dev->irq, b43_interrupt_handler,
b43_interrupt_thread_handler,
IRQF_SHARED, KBUILD_MODNAME, dev);
其在中断上半部b43_interrupt_handler里禁止中断,在中断下半部b43_interrupt_thread_handler里批量读取数据然后重新使能中断(如果要清除中断标志位,则在使能之前先清除一下)。

其余的例子几乎都只使用了一个参数thread_fn,而handler置为NULL,比如
mcs5000_ts.c - Touchscreen driver for MELFAS MCS-5000 controller
	ret = request_threaded_irq(client->irq, NULL, mcs5000_ts_interrupt,
IRQF_TRIGGER_LOW | IRQF_ONESHOT, "mcs5000_ts", data);
又如本文要讨论的 mcp251x.c -CAN bus driver for Microchip 251x CAN Controller with SPI Interface
	ret = request_threaded_irq(spi->irq, NULL, mcp251x_can_ist,
IRQF_TRIGGER_FALLING, DEVICE_NAME, priv);

中断触发
使用IRQF_TRIGGER_FALLING作为中断触发的条件。而mcp2515则是只要有数据发送完成(发给can总线)或有新的数据到来(来自can总线)就会置int引脚低电平,此脚接到0k6410的eint16,向ok6410发送中断中断信号。

MCP2515有八个中断源。CANINTE寄存器包含了使能各中断源的中断使能位。 CANINTF 寄存器包含了各中断源的中断标志位。当发生中断时,INT 引脚将被MCP2515拉为低电平,并保持低电平状态直至MCU清除中断。中断只有在引起相应中断的条件消失后,才会被清除。mcp2515会自动清除中断吗?说明书上没写自动清除。mcp251x.c中却认为可以自动清除?
如果使用低电平触发,则须存在中断上半部,在上半部里面先disable此中断,然后在下半部里面传输完数据之后再enable此中断。
如果不在上半部disable此中断,则由于低电平一直存在,就会一直触发中断,从而一直执行中断上半部,(下半部根本就没机会执行到),造成死机。
如果使用低电平触发,如果中断上半部函数指针设为NULL,那么即使在中断下半部执行disable此中断,也会造成死机。
因为中断发生时,不会立即执行下半部函数,所以有可能没及时禁掉此中断,造成中断(此时仍然低电平)继续触发而使下半部线程大量重复的创建(或许)造成死机。
如果使用下降沿触发,可以不存在上半部,即上半部函数指针可设为NULL,在下半部中可以先disable此中断,然后读取数据再清除中断标志位

******************************************************************
refer to
lkd2

http://blog.csdn.net/zhangjie201412/article/details/7067448

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