linux platform tree 架构下ds18b20驱动程序

/*************************************************************** Copyright 2024-2029. All rights reserved. 文件名 : drv_07_tree_ds18b20.c 作者 : tangmingfei2013@126.com 版本 : V1.0 描述 : ds18b20 驱动程序, GPIO4_PIN19-----ds18b20 port 其他 : 无 日志 : 初版V1.0 2024/1/29 使用方法： typedef struct{ unsigned short temperatureVal; //温度数据, 真实值val = temperatureVal *0.0625 int sign; //符号位,1: 负数， 0： 正数 }Ds18b20Struc; Ds18b20Struc ds_struc; void convert_temp() { read(fd, &ds_struc, sizeof(Ds18b20Struc)); printf("ds18b20 Value: %.02f, sign: %d \n", ds_struc.temperatureVal*0.0625, ds_struc.sign); } ***************************************************************/ #include <linux/types.h> #include <linux/kernel.h> #include <linux/delay.h> #include <linux/ide.h> #include <linux/init.h> #include <linux/module.h> #include <linux/errno.h> #include <linux/gpio.h> #include <linux/cdev.h> #include <linux/device.h> #include <linux/of_gpio.h> #include <linux/semaphore.h> #include <linux/timer.h> #include <linux/irq.h> #include <linux/wait.h> #include <linux/poll.h> #include <linux/fs.h> #include <linux/fcntl.h> #include <linux/platform_device.h> #include <asm/mach/map.h> #include <asm/uaccess.h> #include <asm/io.h> #define DEVICE_NAME "tree_ds18b20" // dev/treeds18b20 typedef struct{ unsigned short temperatureVal; // 温度数据, 真实值val = temperatureVal *0.0625 int sign; // 符号位,1: 负数， 0： 正数 }Ds18b20Struc; /* ds18b20dev设备结构体 */ struct ds18b20stru_dev{ dev_t devid; /* 设备号 */ struct cdev cdev; /* cdev */ struct class *class; /* 类 */ struct device *device; /* 设备 */ int major; /* 主设备号 */ struct device_node *node; /* 设备节点 */ struct gpio_desc *pin; }; static wait_queue_head_t ds18b20_wq; struct ds18b20stru_dev ds18b20dev; /* ds18b20设备 */ /* ds18b20 dirver */ static void tempudelay(int usecs) { int pre,last; pre = ktime_get_boot_ns(); while(1){ last = ktime_get_boot_ns(); if( (last - pre) >= (usecs*1000)) break; } } static int ds18b20_wait_for_ack(void) { int timeout_count = 500; /* 如果是高电平,等待 */ while (gpiod_get_value( ds18b20dev.pin ) && --timeout_count) { udelay(1); } if (!timeout_count) return -1; /* 现在是低电平 */ timeout_count = 500; while (!gpiod_get_value( ds18b20dev.pin ) && --timeout_count) { udelay(1); } if (!timeout_count) return -1; return 0; } static int ds18b20_check( void ) { gpiod_direction_output(ds18b20dev.pin, 0); tempudelay(480); gpiod_direction_input(ds18b20dev.pin); if (ds18b20_wait_for_ack()) { return -1; } else return 0; } static void ds18b20_write_byte( unsigned char byte) { unsigned char k; // write data bit for ( k = 0; k < 8; k++ ) { if (byte & (1<<k)) { gpiod_direction_output(ds18b20dev.pin, 0); tempudelay(2); gpiod_direction_input(ds18b20dev.pin); tempudelay(65); } else { gpiod_direction_output(ds18b20dev.pin, 0); tempudelay(65); gpiod_direction_input(ds18b20dev.pin); tempudelay(2); } } } static unsigned char ds18b20_read_byte( void ) { unsigned char byteVal = 0; unsigned char i; for ( i = 0; i < 8; i++ ) { gpiod_direction_output(ds18b20dev.pin, 0); tempudelay(2); gpiod_direction_input( ds18b20dev.pin ); tempudelay(7); if( gpiod_get_value(ds18b20dev.pin) ) byteVal |= (1<<i); tempudelay(60); } return byteVal; } static bool ds18b20_process( Ds18b20Struc *pdsStruc) { unsigned long tempval; unsigned long flags; unsigned char temp1, temp2; local_irq_save(flags); if (ds18b20_check() == -1) { gpiod_direction_output( ds18b20dev.pin, 1); local_irq_restore(flags); return false; } tempudelay(580); ds18b20_write_byte(0xcc); ds18b20_write_byte(0x44); gpiod_direction_output( ds18b20dev.pin, 1); local_irq_restore(flags); set_current_state(TASK_INTERRUPTIBLE); schedule_timeout(HZ); local_irq_save(flags); if (ds18b20_check() == -1) { gpiod_direction_output(ds18b20dev.pin, 1); local_irq_restore(flags); return false; } tempudelay(580); ds18b20_write_byte(0xcc); ds18b20_write_byte(0xbe); temp1 = ds18b20_read_byte(); temp2 = ds18b20_read_byte(); gpiod_direction_output(ds18b20dev.pin, 1); pdsStruc->sign = 0; if (temp2 > 0x7f) //最高位为1时温度是负 { temp1 = ~temp1; //补码转换，取反加一 temp2 = ~temp2+1; pdsStruc->sign = 1; } //read tempeture value tempval = ((temp2 << 8) | temp1); printk(" [%s line %d ] read value: 0x%04x \r\n",__FUNCTION__, __LINE__, (u16)tempval); pdsStruc->temperatureVal = tempval; local_irq_restore(flags); return true; } /* linux driver 驱动接口： 实现对应的open/read/write等函数，填入file_operations结构体 */ static ssize_t ds18b20_drv_read (struct file *file, char __user *buf, size_t size, loff_t *offset) { Ds18b20Struc dsStruc; bool result; result = ds18b20_process( &dsStruc ); if( result ){ result = copy_to_user(buf, &dsStruc, sizeof(Ds18b20Struc)); } return sizeof(Ds18b20Struc); } static int ds18b20_drv_close(struct inode *node, struct file *file) { printk(" %s line %d \r\n", __FUNCTION__, __LINE__); return 0; } static int ds18b20_drv_open(struct inode *inode, struct file *filp) { filp->private_data = &ds18b20dev; /* 设置私有数据 */ return 0; } /* 定义driver的file_operations结构体 */ static struct file_operations ds18b20_fops = { .owner = THIS_MODULE, .read = ds18b20_drv_read, .open = ds18b20_drv_open, .release = ds18b20_drv_close, }; /* 从platform_device获得GPIO */ static int ds18b20_probe(struct platform_device *pdev) { printk("ds18b20 driver and device was matched!\r\n"); /* 1. 获得硬件信息 */ ds18b20dev.pin = gpiod_get(&pdev->dev, NULL, GPIOD_OUT_HIGH); if (IS_ERR(ds18b20dev.pin)) { printk("%s line %d\n", __FUNCTION__, __LINE__); return -1; } /* 2. device_create */ device_create( ds18b20dev.class, NULL, MKDEV( ds18b20dev.major, 0 ), NULL, DEVICE_NAME); // device name return 0; } static int ds18b20_remove(struct platform_device *pdev) { printk("%s line %d\n", __FUNCTION__, __LINE__); device_destroy( ds18b20dev.class, MKDEV( ds18b20dev.major, 0)); gpiod_put(ds18b20dev.pin); return 0; } /* match the gpio in .dtb //mftang: user's ds18b20, 2024-1-26 // IO: GPIO-4-PIN19 userds18b20s { compatible = "atk-dl6y2c,userds18b20s"; pinctrl-names = "default"; pinctrl-0 = <&pinctrl_gpio_ds18b20>; gpios = <&gpio4 19 GPIO_ACTIVE_LOW>; status = "okay"; }; */ static const struct of_device_id atk_dl6y2c_ds18b20[] = { { .compatible = "atk-dl6y2c,testds18b20" },