Linux SPI驅動學習——調用SPI讀寫函數

• 博客說明
• 開發環境
• 1. 基于W25Q16型FLASH來看SPI的讀寫函數
• 附錄

博客說明

撰寫日期2019.10.25

完稿日期	未完稿
最近維護	暫無
本文作者	multimicro
聯系方式	multimicro@qq.com
資料鏈接	本文無附件資料
GitHub	https://github.com/wifialan/drivers/blob/master/w25q16_spi.c
原文鏈接	https://blog.csdn.net/multimicro/article/details/102738026

開發環境

環境說明詳細信息備注信息

操作系統	Ubunut 18.04
開發板	JZ2440-V3
Linux內核	linux-3.4.2

1. 基于W25Q16型FLASH來看SPI的讀寫函數

這里將w25q16注冊為了一個mtd設備，和字符設備最大不同點就是，不同的設備類型中的方法不同，對于flash硬件，注冊為mtd設備會更加便于操作。這里給出源碼供分析參考:

/** Driver for S3C2440 base board.** Copyright (C) 2019 Alan NWPU <alantian.at@gmail.com>** This program is free software; you can redistribute it and/or modify* it under the terms of the GNU General Public License as published by* the Free Software Foundation; either version 2 of the License, or* (at your option) any later version.** 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* MULTIBEANS, NPU Youyi West Ave, Beilin District, Xi'an, China.*/#include <linux/module.h> /* Every Linux kernel module must include this head */ #include <linux/init.h> /* Every Linux kernel module must include this head */ #include <linux/kernel.h> /* printk() */ #include <linux/fs.h> /* struct fops */ #include <linux/errno.h> /* error codes */ #include <linux/delay.h> #include <linux/moduleparam.h> #include <linux/spi/spi.h>#include <linux/types.h> #include <linux/gpio.h> #include <linux/types.h> #include <linux/irq.h> #include <linux/slab.h> #include <linux/uaccess.h>#include <linux/interrupt.h> #include <linux/pm.h> #include <linux/device.h> #include <asm/irq.h> #include <mach/gpio-nrs.h> #include <mach/regs-gpio.h> #include <mach/gpio.h> #include <mach/hardware.h> #include <plat/gpio-cfg.h> #include <linux/spi/spi.h>#include <linux/mtd/cfi.h> #include <linux/mtd/mtd.h> #include <linux/mtd/partitions.h>#define DRV_NAME "s3c2440_w25q16" #define DRV_AUTHOR "Alan Tian <alantian.at@gmail.com>" #define DRV_DESC "S3C2440 W25Q16 Driver"static int w25q16_bus_spi_probe(struct spi_device *spi); static int w25q16_spi_remove(struct spi_device *spi);struct spi_master *spi_master_p; struct spi_device *spi_flash; struct spi_message *spi_mesg_p;void SPIFlashReadID(int *pMID, int *pDID) {unsigned char tx_buf[4];unsigned char rx_buf[2];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); //先發送tx_buf數組里面的4個字節，然后在讀取2個字節并存入rx_buf中*pMID = rx_buf[0];*pDID = rx_buf[1]; }static void SPIFlashWriteEnable(int enable) {unsigned char val = enable ? 0x06 : 0x04;spi_write(spi_flash, &val, 1); }static unsigned char SPIFlashReadStatusReg1(void) {unsigned char val;unsigned char cmd = 0x05;spi_write_then_read(spi_flash, &cmd, 1, &val, 1);return val; }static unsigned char SPIFlashReadStatusReg2(void) {unsigned char val;unsigned char cmd = 0x35;spi_write_then_read(spi_flash, &cmd, 1, &val, 1);return val; }static void SPIFlashWaitWhenBusy(void) {while (SPIFlashReadStatusReg1() & 1){/* 休眠一段時間 *//* 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后再次判斷 */} }static void SPIFlashWriteStatusReg(unsigned char reg1, unsigned char reg2) { unsigned char tx_buf[4];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;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;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];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;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規定了tx_cnt+rx_cnt < 32* 所以對于大量數據的讀取，不能使用該函數*/unsigned char tx_buf[4]; struct spi_transfer t[] = {{.tx_buf = tx_buf,.len = 4,},{.rx_buf = buf,.len = len,},};struct spi_message m;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(); }/* 構造注冊一個mtd_info* mtd_device_register(master, parts, nr_parts)**//* 首先: 構造注冊spi_driver* 然后: 在spi_driver的probe函數里構造注冊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;/* 判斷參數 */if ((addr & (spi_flash_dev.erasesize - 1)) || (instr->len & (spi_flash_dev.erasesize - 1))){printk("addr/len is not aligned\n");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;/* 判斷參數 */if ((to & (spi_flash_dev.erasesize - 1)) || (len & (spi_flash_dev.erasesize - 1))){printk("addr/len is not aligned\n");return -EINVAL;}for (wlen = 0; wlen < len; wlen += 256){SPIFlashProgram(addr, (unsigned char *)buf, 256);addr += 256;buf += 256;}*retlen = len;return 0; }static struct spi_driver w25q16_spi_driver = {.driver ={.name = "w25q16",.owner = THIS_MODULE,},.probe = w25q16_bus_spi_probe,.remove = __devexit_p(w25q16_spi_remove), };static int __devinit w25q16_bus_spi_probe(struct spi_device *spi) { int mid, did;printk("w25q16 probe function\n");spi_flash = spi;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));/* 構造注冊一個mtd_info* mtd_device_register(master, parts, nr_parts)**//* Setup the MTD structure */spi_flash_dev.name = "w25q16_flash";spi_flash_dev.type = MTD_NORFLASH;spi_flash_dev.flags = MTD_CAP_NORFLASH;spi_flash_dev.size = 0x200000; /* 2M */spi_flash_dev.writesize = 1;spi_flash_dev.writebufsize = 4096; /* 沒有用到 */spi_flash_dev.erasesize = 4096; /* 擦除的最小單位 */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 w25q16_spi_remove(struct spi_device *spi) {mtd_device_unregister(&spi_flash_dev);return 0;}static int __init w25q16_driver_init(void) {int ret;printk("\n************ driver init begin ************\n\n");ret = spi_register_driver(&w25q16_spi_driver);if(ret){spi_unregister_driver(&w25q16_spi_driver);printk(DRV_NAME "\tFailed register spi driver. Error: %d\n",ret);}printk("\n************* driver init end *************\n\n");return ret; }static void __exit w25q16_driver_exit(void) {printk("Unregister w25q16 flash!\n"); // misc_deregister(&w25q16_miscdev);spi_unregister_driver(&w25q16_spi_driver); }module_init(w25q16_driver_init); module_exit(w25q16_driver_exit);MODULE_AUTHOR( DRV_AUTHOR ); MODULE_DESCRIPTION(DRV_DESC); MODULE_LICENSE("GPL");

附錄

Github： w25q16_spi.c

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