函數原型源于2.6.38
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spi驅動結構見
http://blog.csdn.net/songqqnew/article/details/7037583

mcp251x.c幾乎是抄襲dm9000的寫作格式
參考?

dm9000 driver 1

理清一下驅動的線索
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在init函數中注冊spi驅動mcp251x_can_driver
static int __init mcp251x_can_init(void) { DBG("init\n");return spi_register_driver(&mcp251x_can_driver); }在spi驅動mcp251x_can_driver的probe函數中分配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;}//注冊net_deviceregister_candev(net);//net_device的operation結構體指定了操作函數集合static const struct net_device_ops mcp251x_netdev_ops = {.ndo_open = mcp251x_open,.ndo_stop = mcp251x_stop,.ndo_start_xmit = mcp251x_hard_start_xmit,}; }
應用層執行ifconfig can0 up時會調用到mcp251x_open
在mcp251x_open函數中,
//打開設備 open_candev(net); //申請中斷 ret = request_irq(spi->irq, mcp251x_can_irq, /*IRQF_DISABLED |*/ IRQF_TRIGGER_LOW , DEVICE_NAME, priv); //初始化工作隊列，當做中斷(接收)下半部，用于處理接收 INIT_WORK(&priv->irq_work,can_irq_work); //初始化工作隊列，用于處理發送 INIT_WORK(&priv->tx_work, mcp251x_tx_work_handler);
應用層執行write socket時會調用到mcp251x_hard_start_xmit，
在?mcp251x_hard_start_xmit函數中，
//停止協議棧向驅動發送數據(在發送數據的時候需要停止協議棧發來新的需要發送出去的數據)，發送完成后會重新啟用 netif_stop_queue(net); //啟動發送工作隊列，將數據(skb)發送出去 priv->tx_skb = skb; queue_work(priv->wq, &priv->tx_work);

具體看一下這個發送工作隊列函數
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？當然是在中斷處理函數中接收，有中斷產生時，會啟用一個負責接受的工作隊列，即中斷下半部，去接收。并將接收到的數據保存，以供應用層使用read socket等來讀取。
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);//禁止中斷，工作隊列函數中接收完成時會重新使能中斷if (!work_pending(&priv->irq_work))queue_work(priv->wq, &priv->irq_work);//調用工作隊列函數return IRQ_HANDLED; }
接收工作隊列函數
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里有數據。//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) {//如果是發送完成中斷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);//重新開啟}/* receive buffer 1 */if (intf & CANINTF_RX1IF) {//如果是從mcp251x的buffer 1接收到數據的中斷mcp251x_hw_rx(spi, 1);//接收/* the MCP2515 does this automatically */if (mcp251x_is_2510(spi))clear_intf |= CANINTF_RX1IF;//清除mcp251x里的中斷標志}/* receive buffer 0 */if (intf & CANINTF_RX0IF) {//如果是從mcp251x的buffer 0接收到數據的中斷mcp251x_hw_rx(spi, 0);//接收mcp2515的rxb0里的數據，見下/** 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里的中斷標志}/* 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);//重新使能中斷//s3c_gpio_cfgpin(S3C64XX_GPL(8), S3C_GPIO_SFN(3)); }附mcp251x.c源碼
/** CAN bus driver for Microchip 251x 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, 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 <linux/can/core.h> #include <linux/can/dev.h> #include <linux/can/platform/mcp251x.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/platform_device.h> #include <linux/slab.h> #include <linux/spi/spi.h> #include <linux/uaccess.h>#include <linux/gpio.h> #include <plat/gpio-cfg.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/* 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;//中斷設置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 8int 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直接發送的數據\n"); for( i=0;i<len;i++) { DBG("priv->spi_tx_buf[%d]=%x\n",i,priv->spi_tx_buf[i]); }DBG("打印spi直接收到的數據\n"); for( i=0;i<len;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 //根據mcp2515手冊p64，使用spi接口讀取寄存器的步驟是發送 命令03+地址 //接收到的寄存器數據在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); 接收到的寄存器數據在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 //根據mcp2515手冊p64，使用spi接口寫寄存器的步驟是發送 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，對可執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,還需要指定使用那個發送緩沖區發送數據 //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("打印是否擴展幀\n");if (exide){sid = (frame->can_id & CAN_EFF_MASK) >> 18;DBG("是擴展幀\n");}else{sid = frame->can_id & CAN_SFF_MASK; /* Standard ID */DBG("是標準幀\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,即裝載tx0緩沖器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("打印送給spi的數據\n"); for(i=0;i<SPI_TRANSFER_BUF_LEN;i++) { DBG("buf[%d]=%x\n",i,buf[i]); }mcp251x_hw_tx_frame(spi, buf, frame->can_dlc, tx_buf_idx);//裝載到tx0緩沖器mcp251x_write_reg(spi, TXBCTRL(tx_buf_idx), TXBCTRL_TXREQ);//請求發送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,即讀取rx0緩沖器priv->spi_tx_buf[RXBCTRL_OFF] = INSTRUCTION_READ_RXB(buf_idx); /*SPI_TRANSFER_BUF_LEN=14， 即spi的發送和接收緩沖區都設為14 因為mcp2515共返回14個字節，假如是讀rxbuf0,則 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);// 接收數據DBG("打印從spi接收到buf里的數據\n");DBG(" buf_idx=%d\n",buf_idx);int i;for(i=0;i<SPI_TRANSFER_BUF_LEN;i++){DBG(" buf[%d]=%x\n",i,buf[i]);}DBG("打印是否是擴展幀\n");if (buf[RXBSIDL_OFF] & RXBSIDL_IDE) { //buf[RXBSIDL_OFF]即buf[2]即寄存器RXBnSIDL的第4位表示是否是擴展幀 DBG("是擴展幀\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("是標準幀\n");/* Standard ID format *///RXBSIDH的全8位和RXBSIDL的高3位即11位共同組成標準幀的標識符，詳見mcp2515手冊， //所以理論上一條can總線最多可分辨2048個設備(擴展幀也是11位標識符) //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=0x123frame->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，標準幀不使用 //buf[4]=寄存器RXBEID0，標準幀不使用 //buf[5]=寄存器RXBDLC=數據段長度frame->can_dlc = get_can_dlc(buf[RXBDLC_OFF] & RXBDLC_LEN_MASK); //buf[6]-buf[13]=8個數據寄存器RXB0D0-RXB0D7memcpy(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里的數據\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("從應用層收到發送命令\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("要發送的數據是skb\n"); DBG("啟動發送隊列\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);? //刪除定時器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("進入發送隊列\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里的數據\n"); for(i=0;i<20;i++) { DBG("priv->tx_skb->data[%d]=%x\n",i,priv->tx_skb->data[i]); } //將skb里的數據給can_frame以便組織發送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; //發送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);??????? //修改定時器}*/static irqreturn_t mcp251x_can_irq(int irq, void *dev_id) { DBG("有中斷產生\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);? //關中斷，為什么disable_irq死機//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);? //關中斷，為什么disable_irq死機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("進入中斷下半部\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); //讀取中斷標志寄存器，用于判斷是什么中斷DBG("中斷標志=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("是發送完成中斷: \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("是接收到數據中斷: \n"); DBG("receive buffer1有數據\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("是接收到數據中斷: \n"); DBG("receive buffer0有數據\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));??? //開中斷 }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 songDEVICE_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);?? //初始化定時器 //??????? check_timer.expires=jiffies+HZ; //??????? check_timer.function=&check_timer_callback; //??????? check_timer.data=(long)priv;//add_timer(&check_timer);??????? //添加定時器*/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 #endifstatic 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 <celston@katalix.com>, ""Christian Pellegrin <chripell@evolware.org>"); MODULE_DESCRIPTION("Microchip 251x CAN driver"); MODULE_LICENSE("GPL v2");




******************************************************************
幾個疑點分析----以下討論適用于te6410
中斷注冊
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); }原來他調用了request_threaded_irq(),并將中斷處理函數(上半部)handler作為參數傳遞過去。追蹤到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)其中要注意的兩個參數，
irq_handler_t ? handler，中斷處理函數上半部
irq_handler_t ? thread_fn，中斷線程化，這樣直接實現了中斷處理函數的下半部，不必自己再去使用工作隊列實現下半部了
/*
附工作隊列的實現
創建工作隊列，并加入到一個工作者線程里讓其去執行。這個工作者線程可以使內核現成的，也可以使自己心創建的。
創建一個工作隊列work_struct，使用DECLARE_WORK靜態創建一個工作隊列，參數包括隊列名稱和隊列函數，也可使用INIT_WORK動態創建。
創建一個新的工作者線程workqueue_struct,使用create_workqueue，返回值是工作者線程指針。

將工作隊列放到指定的工作者線程中去執行，
int queue_work(struct workqueue_struct *wq, struct work_struct *work)
將工作隊列放到系統已有的events工作者線程中去執行，直接調用sheldule_work(&work)即可。

工作者線程是一個內核線程，運行在進程上下文。
工作者線程被喚醒時，會依次執行它里面的工作隊列----組成了一個鏈表。

*/

搜索2.6.32.2源碼，只發現一個同時使用了這兩個參數的例子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);其在中斷上半部b43_interrupt_handler里禁止中斷，在中斷下半部b43_interrupt_thread_handler里批量讀取數據然后重新使能中斷(如果要清除中斷標志位，則在使能之前先清除一下)。

其余的例子幾乎都只使用了一個參數thread_fn，而handler置為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);又如本文要討論的 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);
中斷觸發
使用IRQF_TRIGGER_FALLING作為中斷觸發的條件。而mcp2515則是只要有數據發送完成(發給can總線)或有新的數據到來(來自can總線)就會置int引腳低電平，此腳接到0k6410的eint16，向ok6410發送中斷中斷信號。

MCP2515有八個中斷源。CANINTE寄存器包含了使能各中斷源的中斷使能位。 CANINTF 寄存器包含了各中斷源的中斷標志位。當發生中斷時，INT 引腳將被MCP2515拉為低電平，并保持低電平狀態直至MCU清除中斷。中斷只有在引起相應中斷的條件消失后，才會被清除。mcp2515會自動清除中斷嗎？說明書上沒寫自動清除。mcp251x.c中卻認為可以自動清除？

如果使用低電平觸發，則須存在中斷上半部，在上半部里面先disable此中斷，然后在下半部里面傳輸完數據之后再enable此中斷。
如果不在上半部disable此中斷，則由于低電平一直存在，就會一直觸發中斷，從而一直執行中斷上半部，(下半部根本就沒機會執行到)，造成死機。

如果使用低電平觸發，如果中斷上半部函數指針設為NULL，那么即使在中斷下半部執行disable此中斷，也會造成死機。
因為中斷發生時，不會立即執行下半部函數，所以有可能沒及時禁掉此中斷，造成中斷(此時仍然低電平)繼續觸發而使下半部線程大量重復的創建(或許)造成死機。

如果使用下降沿觸發，可以不存在上半部，即上半部函數指針可設為NULL，在下半部中可以先disable此中斷，然后讀取數據再清除中斷標志位

******************************************************************

refer to
lkd2
http://blog.csdn.net/zhangjie201412/article/details/7067448

轉載于:https://www.cnblogs.com/-song/archive/2012/05/24/3331872.html

總結

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