m25p10驱动测试
目标:S5PC100平台上编写一个简单的spi驱动模块,在probe阶段实现对m25p10的ID号探测、flash擦除、flash状态读取、flash写入、flash读取等操作。代码已经经过测试,运行于2.6.35内核。理解下面代码需要参照m25p10的芯片手册。其实下面的代码和处理器没有太大关系,这也是spi子系统的分层特点。
urning its value in the location * Return the status register value. * Returns negative if error occurred. */ static int read_sr(struct m25p10a *flash) { ssize_t retval; u8 code = CMD_RDSR; u8 val; retval = spi_write_then_read(flash->spi, &code, 1, &val, 1); if (retval < 0) { dev_err(&flash->spi->dev, "error %d reading SR\n", (int) retval); return retval; } return val; } /* * Service routine to read status register until ready, or timeout occurs. * Returns non-zero if error. */ static int wait_till_ready(struct m25p10a *flash) { int count; int sr; /* one chip guarantees max 5 msec wait here after page writes, * but potentially three seconds (!) after page erase. */ for (count = 0; count < MAX_READY_WAIT_COUNT; count++) { if ((sr = read_sr(flash)) < 0) break; else if (!(sr & SR_WIP)) return 0; /* REVISIT sometimes sleeping would be best */ } printk( "in (%s): count = %d\n", count ); return 1; } /* * Set write enable latch with Write Enable command. * Returns negative if error occurred. */ static inline int write_enable( struct m25p10a *flash ) { flash->cmd[0] = CMD_WRITE_ENABLE; return spi_write( flash->spi, flash->cmd, 1 ); } /* * Erase the whole flash memory * * Returns 0 if successful, non-zero otherwise. */ static int erase_chip( struct m25p10a *flash ) { /* Wait until finished previous write command. */ if (wait_till_ready(flash)) return -1; /* Send write enable, then erase commands. */ write_enable( flash ); flash->cmd[0] = CMD_BULK_ERASE; return spi_write( flash->spi, flash->cmd, 1 ); } /* * Read an address range from the flash chip. The address range * may be any size provided it is within the physical boundaries. */ static int m25p10a_read( struct m25p10a *flash, loff_t from, size_t len, char *buf ) { int r_count = 0, i; flash->cmd[0] = CMD_READ_BYTES; flash->cmd[1] = from >> 16; flash->cmd[2] = from >> 8; flash->cmd[3] = from; #if 1 struct spi_transfer st[2]; struct spi_message msg; spi_message_init( &msg ); memset( st, 0, sizeof(st) ); flash->cmd[0] = CMD_READ_BYTES; flash->cmd[1] = from >> 16; flash->cmd[2] = from >> 8; flash->cmd[3] = from; st[ 0 ].tx_buf = flash->cmd; st[ 0 ].len = CMD_SZ; spi_message_add_tail( &st[0], &msg ); st[ 1 ].rx_buf = buf; st[ 1 ].len = len; spi_message_add_tail( &st[1], &msg ); mutex_lock( &flash->lock ); /* Wait until finished previous write command. */ if (wait_till_ready(flash)) { mutex_unlock( &flash->lock ); return -1; } spi_sync( flash->spi, &msg ); r_count = msg.actual_length - CMD_SZ; printk( "in (%s): read %d bytes\n", __func__, r_count ); for( i = 0; i < r_count; i++ ) { printk( "0x%02x\n", buf[ i ] ); } mutex_unlock( &flash->lock ); #endif return 0; } /* * Write an address range to the flash chip. Data must be written in * FLASH_PAGE_SIZE chunks. The address range may be any size provided * it is within the physical boundaries. */ static int m25p10a_write( struct m25p10a *flash, loff_t to, size_t len, const char *buf ) { int w_count = 0, i, page_offset; struct spi_transfer st[2]; struct spi_message msg; #if 1 if (wait_till_ready(flash)) { //读状态,等待ready mutex_unlock( &flash->lock ); return -1; } #endif write_enable( flash ); //写使能 spi_message_init( &msg ); memset( st, 0, sizeof(st) ); flash->cmd[0] = CMD_PAGE_PROGRAM; flash->cmd[1] = to >> 16; flash->cmd[2] = to >> 8; flash->cmd[3] = to; st[ 0 ].tx_buf = flash->cmd; st[ 0 ].len = CMD_SZ; spi_message_add_tail( &st[0], &msg ); st[ 1 ].tx_buf = buf; st[ 1 ].len = len; spi_message_add_tail( &st[1], &msg ); mutex_lock( &flash->lock ); /* get offset address inside a page */ page_offset = to % FLASH_PAGE_SIZE; /* do all the bytes fit onto one page? */ if( page_offset + len <= FLASH_PAGE_SIZE ) { // yes st[ 1 ].len = len; printk("%d, cmd = %d\n", st[ 1 ].len, *(char *)st[0].tx_buf); //while(1) { spi_sync( flash->spi, &msg ); } w_count = msg.actual_length - CMD_SZ; } else { // no } printk( "in (%s): write %d bytes to flash in total\n", __func__, w_count ); mutex_unlock( &flash->lock ); return 0; } static int check_id( struct m25p10a *flash ) { char buf[10] = {0}; flash->cmd[0] = CMD_READ_ID; spi_write_then_read( flash->spi, flash->cmd, 1, buf, 3 ); printk( "Manufacture ID: 0x%x\n", buf[0] ); printk( "Device ID: 0x%x\n", buf[1] | buf[2] << 8 ); return buf[2] << 16 | buf[1] << 8 | buf[0]; } static int m25p10a_probe(struct spi_device *spi) { int ret = 0; struct m25p10a *flash; char buf[ 256 ]; printk( "%s was called\n", __func__ ); flash = kzalloc( sizeof(struct m25p10a), GFP_KERNEL ); if( !flash ) { return -ENOMEM; } flash->spi = spi; mutex_init( &flash->lock ); /* save flash as driver's private data */ spi_set_drvdata( spi, flash ); check_id( flash ); //读取ID #if 1 ret = erase_chip( flash ); //擦除 if( ret < 0 ) { printk( "erase the entirely chip failed\n" ); } printk( "erase the whole chip done\n" ); memset( buf, 0x7, 256 ); m25p10a_write( flash, 0, 20, buf); //0地址写入20个7 memset( buf, 0, 256 ); m25p10a_read( flash, 0, 25, buf ); //0地址读出25个数 #endif return 0; } static int m25p10a_remove(struct spi_device *spi) { return 0; } static struct spi_driver m25p10a_driver = { .probe = m25p10a_probe, .remove = m25p10a_remove, .driver = { .name = "m25p10a", }, }; static int __init m25p10a_init(void) { return spi_register_driver(&m25p10a_driver); } static void __exit m25p10a_exit(void) { spi_unregister_driver(&m25p10a_driver); } module_init(m25p10a_init); module_exit(m25p10a_exit); MODULE_DESCRIPTION("m25p10a driver for FS_S5PC100"); MODULE_LICENSE("GPL");