裝置樹學習之（十）spi flash

開發板：tiny4412sdk + s702 + 4gb flash 

要移植的核心版本：linux-4.4.0 （支援device tree） 

u-boot版本：友善之臂自帶的 u-boot 2010.12 

busybox版本：busybox 1.25

驅動外接的8m的 spi flash，註冊為塊裝置。

裝置樹：

&spi_0 ;

};};

spi-max-frequency = <10000000>;表示最大速率

**：

#include 

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#include 
/* 參考:
* drivers\mtd\devices\mtdram.c
* drivers/mtd/devices/m25p80.c
*/static
struct spi_device *spi_flash;
void spiflashreadid(int *pmid, int *pdid)
static
void spiflashwriteenable(int enable)
static
unsigned
char spiflashreadstatusreg1(void)
static
unsigned
char spiflashreadstatusreg2(void)
static
void spiflashwaitwhenbusy(void)
}static
void spiflashwritestatusreg(unsigned
char reg1, unsigned
char reg2)
static
void spiflashclearprotectforstatusreg(void)
static
void spiflashclearprotectfordata(void)
/* erase 4k */
void spiflasherasesector(unsigned
int addr)
/* program */
void spiflashprogram(unsigned
int addr, unsigned
char *buf, int len)
,        ,
};struct spi_message  m;
//printk("%s\n",__func__);
tx_buf[0] = 0x02;
tx_buf[1] = addr >> 16;
tx_buf[2] = addr >> 8;
tx_buf[3] = addr & 0xff;
spiflashwriteenable(1);
spi_message_init(&m);
spi_message_add_tail(&t[0], &m);
spi_message_add_tail(&t[1], &m);
spi_sync(spi_flash, &m);
spiflashwaitwhenbusy();
}void spiflashread(unsigned
int addr, unsigned
char *buf, int len)
,        ,
};struct spi_message  m;
//printk("%s\n",__func__);
tx_buf[0] = 0x03;
tx_buf[1] = addr >> 16;
tx_buf[2] = addr >> 8;
tx_buf[3] = addr & 0xff;
spi_message_init(&m);
spi_message_add_tail(&t[0], &m);
spi_message_add_tail(&t[1], &m);
spi_sync(spi_flash, &m);
}static
void spiflashinit(void)
/* 構造註冊乙個mtd_info
* mtd_device_register(master, parts, nr_parts)
* */
/* 首先: 構造註冊spi_driver
* 然後: 在spi_driver的probe函式裡構造註冊mtd_info
*/static
struct mtd_info spi_flash_dev;
static
int spi_flash_erase(struct mtd_info *mtd, struct erase_info *instr)
for (len = 0; len < instr->len; len += 4096)
instr->state = mtd_erase_done;
mtd_erase_callback(instr);
return0;}
static
int spi_flash_read(struct mtd_info *mtd, loff_t from, size_t len,
size_t *retlen, u_char *buf)
static
int spi_flash_write(struct mtd_info *mtd, loff_t to, size_t len,
size_t *retlen, const u_char *buf)
if (len <= 256)
else
if (len % 256 != 0)
}*retlen = len;
return0;}
static
int spi_flash_probe(struct spi_device *spi)
printk("%s\n",__func__);
//s3c2410_gpio_cfgpin(spi->chip_select, s3c2410_gpio_output);
spiflashinit();
spiflashreadid(&mid, &did);
printk("spi flash id: %02x %02x\n", mid, did);
memset(&spi_flash_dev, 0, sizeof(spi_flash_dev));
//setup the mtd structure
spi_flash_dev.name = "spi_flash";
spi_flash_dev.type = mtd_norflash;
spi_flash_dev.flags = mtd_cap_norflash;
spi_flash_dev.size = 0x800000; 
spi_flash_dev.writesize = 1;
spi_flash_dev.writebufsize = 4096; 
spi_flash_dev.erasesize = 4096; 
spi_flash_dev.owner = this_module;
spi_flash_dev._erase = spi_flash_erase;
spi_flash_dev._read  = spi_flash_read;
spi_flash_dev._write = spi_flash_write;
mtd_device_register(&spi_flash_dev, null, 0);
return0;}
static
int spi_flash_remove(struct spi_device *spi)
static
const
struct of_device_id spi_flash_ids = ,
};static
struct spi_driver spi_flash_drv =
,    .probe      = spi_flash_probe,
.remove     = spi_flash_remove,
};static
int spi_flash_init(void)
static
void spi_flash_exit(void)
module_init(spi_flash_init);
module_exit(spi_flash_exit);
module_license("gpl");

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