SSE3052: Embedded Systems Practice

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1 SSE3052: Embedded Systems Practice Minwoo Ahn Computer Systems Laboratory Sungkyunkwan University SSE3052: Embedded Systems Practice, Spring 2018, Jinkyu Jeong

2 Today s goal Access soft device(segment & LED) by ioctl App.c Device driver ioctl(fd, cmd, para)? User Kernel(goldfish) Hardware(soft devices) SSE3052: Embedded Systems Practice, Spring 2018, Jinkyu Jeong (jinkyu@skku.edu) 2

3 What is ioctl()? ioctl (fd, cmd, param) User application User Kernel Syscall call interface File operation of fd ioctl() Device driver ioctl() { return } Device SSE3052: Embedded Systems Practice, Spring 2018, Jinkyu Jeong (jinkyu@skku.edu) 3

4 Custom ioctl() You can define your own ioctl() SSE3052: Embedded Systems Practice, Spring 2018, Jinkyu Jeong 4

5 Write device driver static long segment_ioctl(struct file *file, unsigned int cmd, unsigned long para) static long led_ioctl(struct file *file, unsigned int cmd, unsigned long para) SSE3052: Embedded Systems Practice, Spring 2018, Jinkyu Jeong 5

6 Write device driver (cont.) static ssize_t segment_read(struct file *file, char user *buf, size_t size, loff_t *loff) static ssize_t segment_write(struct file *file, const char user *buf, size_t size, loff_t *loff) static ssize_t led_read(struct file *file, char user *buf, size_t size, loff_t *loff) static ssize_t segment_write(struct file *file, const char user *buf, size_t size, loff_t *loff) SSE3052: Embedded Systems Practice, Spring 2018, Jinkyu Jeong 6

7 Read & Write operation SSE3052: Embedded Systems Practice, Spring 2018, Jinkyu Jeong 7

$h> User code #define CMD1 0x01 //print input #define CMD2 0x02 //print (input + 1) #define CMD3 0x03 //print (input + 2) int main(int argc, char *argv[]){ int fd; } fd = open( /dev/segment, O_RDWR);$

8 ioctl() operation #include <stdio.h> User code #define CMD1 0x01 //print input #define CMD2 0x02 //print (input + 1) #define CMD3 0x03 //print (input + 2) int main(int argc, char *argv[]){ int fd; } fd = open( /dev/segment, O_RDWR); ioctl(fd, CMD2, 3); close(fd); return 0; Device driver #define CMD1 0x01 #define CMD2 0x02 #define CMD3 0x03 static long segment_ioctl(struct file *file, unsigned int cmd, unsigned long para) { swtich(cmd) { case CMD1: ;break; case CMD2: ;break; case CMD3: printk( %d\n, (int)para + 1); break; }; } SSE3052: Embedded Systems Practice, Spring 2018, Jinkyu Jeong (jinkyu@skku.edu) 8

9 Write user code Download mini_calc_ioctl.c Access device by ioctl() SSE3052: Embedded Systems Practice, Spring 2018, Jinkyu Jeong 9

10 Compile goldfish Kernel build $export ARCH=x86_64 $export CROSS_COMPILE=~/x86_64-linux-android-4.9/bin/x86_64- linux-android- $make x86_64_emu_defconfig $make menuconfig Device_driver -> misc -> 7segment & LED on $make j4 Move kernel Image $cd ~/Android/Sdk/system-image/android-24/google_apis/x86_64 $mv kernel-qemu kernel-qemu.old $mv kernel-ranchu kernel-ranchu.old $cp ~/goldfish/arch/x86/boot/bzimage kernel-qemu SSE3052: Embedded Systems Practice, Spring 2018, Jinkyu Jeong 10

11 Run user code Compile with pie option $~/my-android-toolchain/bin/x86_64-linux-android-gcc -pie user.c Run emulator $~/emu-2.2-release/external/qemu/objs/emulator -avd my_avd Copy to /data/local/tmp and execute $~/Android/Sdk/platform-tools/adb push a.out /data/local/tmp $~/Android/Sdk/platform-tools/adb shell SSE3052: Embedded Systems Practice, Spring 2018, Jinkyu Jeong 11

12 Exercise Make your own segment_ioctl() and led_ioctl() Your segment_ioctl() should include, SEGMENT_WRITE_[x: 0-6]: write input value on xth segment SEGMENT_WRITE_ALL: write input value on segment SEGMENT_READ_[x: 0-6]: read value from xth segment SEGMENT_READ_ALL: read value from segment SEGMENT_ADD: read value from segment and add input SEGMENT_SUB: read value from segment and sub input SEGMENT_MUL: read value from segment and mul input SEGMENT_DIV: read value from segment and div input For (add, sub, mul, div) operations, print max and 0 when result is out of bound Return 0 for success, -1 for failure SSE3052: Embedded Systems Practice, Spring 2018, Jinkyu Jeong (jinkyu@skku.edu) 12

13 Exercise (cont.) Make your own segment_ioctl() and led_ioctl() Your led_ioctl() should include, LED_ON_[x: 0~6]: turn on xth LED LED_ON_ALL: turn on all LEDs LED_OFF_[x:0-6]: turn off xth LED LED_OFF_ALL: turn off all LEDs LED_[x: 0~6]_[y: gray,white,red,yellow,green,sky,purple]: change color of xth LED to y LED_ALL_[y: gray,white,red,yellow,green,sky,purple]: change color of all LED to y Return 0 for success, -1 for failure SSE3052: Embedded Systems Practice, Spring 2018, Jinkyu Jeong (jinkyu@skku.edu) 13

SSE3052: Embedded Systems Practice

SSE3052: Embedded Systems Practice Minwoo Ahn minwoo.ahn@csl.skku.edu Computer Systems Laboratory Sungkyunkwan University http://csl.skku.edu SSE3052: Embedded Systems Practice, Spring 2018, Jinkyu Jeong