设备树学习之（十）spi flash

转载自：http://blog.csdn.net/lizuobin2/article/details/54565214

开发板：tiny4412SDK + S702 + 4GB Flash
要移植的内核版本：Linux-4.4.0 （支持device tree）
u-boot版本：友善之臂自带的 U-Boot 2010.12
busybox版本：busybox 1.25

目标：
驱动外接的8M的 spi flash，注册为块设备。

设备树：

&spi_0 {        status = "okay";        cs-gpios = <&gpb 1 GPIO_ACTIVE_HIGH>;        spi_flash@0 {                compatible = "tiny4412,spi_flash";                spi-max-frequency = <10000000>;                reg = <0>;                controller-data {                        samsung,spi-feedback-delay = <0>;                };        };};
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这里指定的 reg = <0> 表示的该 spi 设备引用第一个 cs-gpios
spi-max-frequency = <10000000>;表示最大速率

代码：

#include <linux/clk.h>#include <linux/delay.h>#include <linux/firmware.h>#include <linux/gpio.h>#include <linux/i2c.h>#include <linux/init.h>#include <linux/media.h>#include <linux/module.h>#include <linux/of_gpio.h>#include <linux/regulator/consumer.h>#include <linux/sizes.h>#include <linux/slab.h>#include <linux/spi/spi.h>#include <linux/videodev2.h>#include <media/media-entity.h>#include <media/v4l2-ctrls.h>#include <media/v4l2-device.h>#include <media/v4l2-subdev.h>#include <media/v4l2-mediabus.h>#include <media/s5c73m3.h>#include <media/v4l2-of.h>#include <linux/mtd/mtd.h>/* 参考: * drivers\mtd\devices\mtdram.c * drivers/mtd/devices/m25p80.c */static struct spi_device *spi_flash;void SPIFlashReadID(int *pMID, int *pDID){    unsigned char tx_buf[4];    unsigned char rx_buf[2];    //printk("%s\n",__func__);    tx_buf[0] = 0x90;    tx_buf[1] = 0;    tx_buf[2] = 0;    tx_buf[3] = 0;    spi_write_then_read(spi_flash, tx_buf, 4, rx_buf, 2);    *pMID = rx_buf[0];    *pDID = rx_buf[1];}static void SPIFlashWriteEnable(int enable){    unsigned char val = enable ? 0x06 : 0x04;    //printk("%s\n",__func__);    spi_write(spi_flash, &val, 1);}static unsigned char SPIFlashReadStatusReg1(void){    unsigned char val;    unsigned char cmd = 0x05;    //printk("%s\n",__func__);    spi_write_then_read(spi_flash, &cmd, 1, &val, 1);    return val;}static unsigned char SPIFlashReadStatusReg2(void){    unsigned char val;    unsigned char cmd = 0x35;    //printk("%s\n",__func__);    spi_write_then_read(spi_flash, &cmd, 1, &val, 1);    return val;}static void SPIFlashWaitWhenBusy(void){    //printk("%s\n",__func__);    while (SPIFlashReadStatusReg1() & 1)    {        /* 休眠一段时间 */        /* Sector erase time : 60ms         * Page program time : 0.7ms         * Write status reg time : 10ms         */        set_current_state(TASK_INTERRUPTIBLE);        schedule_timeout(HZ / 100); /* 休眠10MS后再次判断 */    }}static void SPIFlashWriteStatusReg(unsigned char reg1, unsigned char reg2){    unsigned char tx_buf[4];    //printk("%s\n",__func__);    SPIFlashWriteEnable(1);    tx_buf[0] = 0x01;    tx_buf[1] = reg1;    tx_buf[2] = reg2;    spi_write(spi_flash, tx_buf, 3);    SPIFlashWaitWhenBusy();}static void SPIFlashClearProtectForStatusReg(void){    unsigned char reg1, reg2;    //printk("%s\n",__func__);    reg1 = SPIFlashReadStatusReg1();    reg2 = SPIFlashReadStatusReg2();    reg1 &= ~(1 << 7);    reg2 &= ~(1 << 0);    SPIFlashWriteStatusReg(reg1, reg2);}static void SPIFlashClearProtectForData(void){    /* cmp=0,bp2,1,0=0b000 */    unsigned char reg1, reg2;    //printk("%s\n",__func__);    reg1 = SPIFlashReadStatusReg1();    reg2 = SPIFlashReadStatusReg2();    reg1 &= ~(7 << 2);    reg2 &= ~(1 << 6);    SPIFlashWriteStatusReg(reg1, reg2);}/* erase 4K */void SPIFlashEraseSector(unsigned int addr){    unsigned char tx_buf[4];    //printk("%s\n",__func__);    tx_buf[0] = 0x20;    tx_buf[1] = addr >> 16;    tx_buf[2] = addr >> 8;    tx_buf[3] = addr & 0xff;    SPIFlashWriteEnable(1);    spi_write(spi_flash, tx_buf, 4);    SPIFlashWaitWhenBusy();}/* program */void SPIFlashProgram(unsigned int addr, unsigned char *buf, int len){    unsigned char tx_buf[4];    struct spi_transfer t[] =    {        {            .tx_buf     = tx_buf,            .len        = 4,        },        {            .tx_buf     = buf,            .len        = 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){    /* spi_write_then_read规定了tx_cnt+rx_cnt < 32     * 所以对于大量数据的读取，不能使用该函数     */    unsigned char tx_buf[4];    struct spi_transfer t[] =    {        {            .tx_buf     = tx_buf,            .len        = 4,        },        {            .rx_buf     = buf,            .len        = 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){    SPIFlashClearProtectForStatusReg();    SPIFlashClearProtectForData();}/* 构造注册一个mtd_info * mtd_device_register(master, parts, nr_parts) * *//* 首先: 构造注册spi_driver * 然后: 在spi_driver的probe函数里构造注册mtd_info */static struct mtd_info spi_flash_dev;static int spi_flash_erase(struct mtd_info *mtd, struct erase_info *instr){    unsigned int addr = instr->addr;    unsigned int len  = 0;    //判断参数     if ((addr & (spi_flash_dev.erasesize - 1)) || (instr->len & (spi_flash_dev.erasesize - 1)))    {        printk("spi_flash_erase addr/len is not aligned %x %x\n",(unsigned int)instr->addr,(unsigned int)instr->len);        return -EINVAL;    }    for (len = 0; len < instr->len; len += 4096)    {        SPIFlashEraseSector(addr);        addr += 4096;    }    instr->state = MTD_ERASE_DONE;    mtd_erase_callback(instr);    return 0;}static int spi_flash_read(struct mtd_info *mtd, loff_t from, size_t len,                          size_t *retlen, u_char *buf){    SPIFlashRead(from, buf, len);    *retlen = len;    return 0;}static int spi_flash_write(struct mtd_info *mtd, loff_t to, size_t len,                           size_t *retlen, const u_char *buf){    unsigned int addr = to;    unsigned int wlen  = 0;    unsigned int i;    //判断参数    if ((to & (spi_flash_dev.erasesize - 1)))    {        printk("spi_flash_write addr/len is not aligned %x %x\n",(unsigned int)to,(unsigned int)len);        return -EINVAL;    }    if (len <= 256)    {        SPIFlashProgram(addr, (unsigned char *)buf, len);    }    else    {        for (i = 0; i < len / 256; i ++)        {            SPIFlashProgram(addr, (unsigned char *)buf, 256);            addr += 256;            buf += 256;        }        if (len % 256 != 0)        {            SPIFlashProgram(addr, (unsigned char *)buf, len % 256);        }    }    *retlen = len;    return 0;}static int spi_flash_probe(struct spi_device *spi){    int mid, did, ret;    spi_flash = spi;    spi->mode = SPI_MODE_0;    ret = spi_setup(spi);    if (ret < 0)    {        printk("spi_setup error\n");    }    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);    return 0;}static int spi_flash_remove(struct spi_device *spi){    mtd_device_unregister(&spi_flash_dev);    return 0;}static const struct of_device_id spi_flash_ids[] = {    { .compatible = "tiny4412,spi_flash" },    { }};static struct spi_driver spi_flash_drv ={    .driver = {        .name   = "spi_flash",    },    .probe      = spi_flash_probe,    .remove     = spi_flash_remove,};static int spi_flash_init(void){    printk("init\n");    return spi_register_driver(&spi_flash_drv);}static void spi_flash_exit(void){    spi_unregister_driver(&spi_flash_drv);}module_init(spi_flash_init);module_exit(spi_flash_exit);MODULE_LICENSE("GPL");
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