Linux驱动分析之SPI驱动架构

//SPI控制器structspi_master {
structdevicedev;
structlist_headlist; //控制器链表//控制器对应的SPI总线号 SPI-2 对应bus_num= 2s16bus_num;
u16num_chipselect;//控制器支持的片选数量，即能支持多少个spi设备 u16dma_alignment;//DMA缓冲区对齐方式u16mode_bits;// mode标志/* other constraints relevant to this driver */u16flags;
#define SPI_MASTER_HALF_DUPLEX  BIT(0)  /* can't do full duplex */#define SPI_MASTER_NO_RX  BIT(1)    /* can't do buffer read */#define SPI_MASTER_NO_TX  BIT(2)    /* can't do buffer write */// 并发同步时使用spinlock_tbus_lock_spinlock;
structmutexbus_lock_mutex;
/* flag indicating that the SPI bus is locked for exclusive use */boolbus_lock_flag;
//设置SPI mode和时钟， 在spi_add_device中调用int      (*setup)(structspi_device*spi);
//传输数据函数, 实现数据的双向传输int      (*transfer)(structspi_device*spi,
structspi_message*mesg);
//注销时回调void      (*cleanup)(structspi_device*spi);
/** These hooks are for drivers that want to use the generic* master transfer queueing mechanism. If these are used, the* transfer() function above must NOT be specified by the driver.* Over time we expect SPI drivers to be phased over to this API.*/boolqueued;
structkthread_workerkworker;
structtask_struct*kworker_task;
structkthread_workpump_messages;
spinlock_tqueue_lock;
structlist_headqueue;
structspi_message*cur_msg;
boolbusy;
boolrunning;
boolrt;
int (*prepare_transfer_hardware)(structspi_master*master);
int (*transfer_one_message)(structspi_master*master,
structspi_message*mesg);
int (*unprepare_transfer_hardware)(structspi_master*master);
}

//SPI驱动，和platform_driver,i2c_driver类似structspi_driver {
conststructspi_device_id*id_table;
int  (*probe)(structspi_device*spi);
int  (*remove)(structspi_device*spi);
void  (*shutdown)(structspi_device*spi);
int  (*suspend)(structspi_device*spi, pm_message_tmesg);
int  (*resume)(structspi_device*spi);
structdevice_driverdriver;
};

//SPI 设备structspi_device {
structdevicedev;
structspi_master*master; //指向SPI控制器u32max_speed_hz; //最大速率u8chip_select; //片选u8mode; //SPI设备模式，使用下面的宏#define  SPI_CPHA  0x01      /* clock phase */#define  SPI_CPOL  0x02      /* clock polarity */#define  SPI_MODE_0  (0|0)      /* (original MicroWire) */#define  SPI_MODE_1  (0|SPI_CPHA)#define  SPI_MODE_2  (SPI_CPOL|0)#define  SPI_MODE_3  (SPI_CPOL|SPI_CPHA)#define  SPI_CS_HIGH  0x04      /* chipselect active high? */#define  SPI_LSB_FIRST  0x08      /* per-word bits-on-wire */#define  SPI_3WIRE  0x10      /* SI/SO signals shared */#define  SPI_LOOP  0x20      /* loopback mode */#define  SPI_NO_CS  0x40      /* 1 dev/bus, no chipselect */#define  SPI_READY  0x80      /* slave pulls low to pause */u8bits_per_word;
intirq;
void*controller_state; //控制器运行状态void*controller_data; //特定板子为控制器定义的数据charmodalias[SPI_NAME_SIZE];
};

//SPI传输数据结构体structspi_message {
structlist_headtransfers; // spi_transfer链表头structspi_device*spi; //spi设备unsignedis_dma_mapped:1;
//发送完成回调void      (*complete)(void*context);
void*context;
unsignedactual_length;
intstatus;
/* for optional use by whatever driver currently owns the* spi_message ...  between calls to spi_async and then later* complete(), that's the spi_master controller driver.*/structlist_headqueue;
void*state;
};

// 该结构体是spi_message下的子单元，structspi_transfer {
constvoid*tx_buf;// 发送的数据缓存区void*rx_buf;// 接收的数据缓存区unsignedlen;
dma_addr_ttx_dma; //tx_buf的DMA地址dma_addr_trx_dma; //rx_buf的DMA地址unsignedcs_change:1;
u8bits_per_word;
u16delay_usecs;
u32speed_hz;
structlist_headtransfer_list;
};

//分配一个spi_masterstructspi_master*spi_alloc_master(structdevice*dev, unsignedsize)
//注册和注销spi_masterintspi_register_master(structspi_master*master)
voidspi_unregister_master(structspi_master*master)
//注册和注销spi_driverintspi_register_driver(structspi_driver*sdrv)
voidspi_unregister_driver(structspi_driver*sdrv)
//初始化spi_messagevoidspi_message_init(structspi_message*m)
//向spi_message添加transfersvoidspi_message_add_tail(structspi_transfer*t, structspi_message*m)
//异步发送spi_messageintspi_async(structspi_device*spi, structspi_message*message)
//同步发送spi_messageintspi_sync(structspi_device*spi, structspi_message*message)
//spi同步写(封装了上面的函数)intspi_write(structspi_device*spi, constvoid*buf, size_tlen)
//spi同步读(封装了上面的函数)intspi_read(structspi_device*spi, void*buf, size_tlen)
//同步写并读取(封装了上面的函数)intspi_write_then_read(structspi_device*spi,
constvoid*txbuf, unsignedn_tx,
void*rxbuf, unsignedn_rx)