can3--socketcan之mcp251x.c
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
******************************************************************
在init函数中注册spi驱动 mcp251x_can_driver
应用层执行ifconfig can0 up时会调用到mcp251x_open
在 mcp251x_open函数中,
应用层执行write socket时会调用到 mcp251x_hard_start_xmit，
在 mcp251x_hard_start_xmit函数中，
具体看一下这个发送工作队列函数
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。
接收工作队列函数
******************************************************************
几个疑点分析----以下讨论适用于te6410
中断注册
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
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
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
******************************************************************
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_devicestatic 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_open
在 mcp251x_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，
在 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 * <[email protected]> * * 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<len;i++) { DBG("priv->spi_tx_buf[%d]=%x\n",i,priv->spi_tx_buf[i]); } DBG("打印spi直接收到的数据\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<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);//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<SPI_TRANSFER_BUF_LEN;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 <[email protected]>, " "Christian Pellegrin <[email protected]>"); 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