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几乎是抄袭dm9000的写作格式
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几乎是抄袭dm9000的写作格式
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
* <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 <celston@katalix.com>, "
"Christian Pellegrin <chripell@evolware.org>");
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
/*
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
