linux-device-driver

问题 I am using Petalinux for a Xilinx Zynq application, and I am new to kernel driver development. I created a kernel module for a platform driver for an AXI FIFO interface. The devices seems to be recognised from the device tree using the .of_match_table, since I can see the correct memory space reserved with cat /proc/iomem . If I search for the driver name xxx I get ./lib/modules/4.4.0-xilinx/extra/xxx.ko ./sys/bus/platform/drivers/xxx ./sys/module/xxx ./sys/module/xxx/drivers/platform:xxx I

问题 I have written a user defined function in my device driver and I want to call it from user space application program. How do I achieve this? What I mean by user defined function is, any function other than the kernel defined functions. Pointers to which is defined in struct file_operations , as below. struct file_operations { struct module *owner; loff_t (*llseek) (struct file *, loff_t, int); ssize_t (*read) (struct file *, char *, size_t, loff_t *); ssize_t (*write) (struct file *, const

问题 I am learning about the driver and looking into the watchdog driver code where some value is being written to /sys/devices/virtual/wdc_per now I guess this is the logic how driver gets its value from userspace and exposed file in user space is "sys/devices/virtual/wdc_per" But now how actually this value from wdc_per is reached to driver, there must some callback maintained In My case its GPIO based Watchdog driver and gpio_wdt.c may be having this callback. But I really could not figure out

问题 hi I am newbie please help me i have enabled the Uart in linux source and created a image,and while kernel boot time its showing me the log Serial: 8250/16550 driver, 5 ports, IRQ sharing disabled serial8250.0: ttyS0 at MMIO 0x4000c000 (irq = 5) is a 16550A console [ttyS0] enabled serial8250.2: ttyS1 at MMIO 0x40098000 (irq = 7) is a 16550A serial8250.3: ttyS2 at MMIO 0x4009c000 (irq = 8) is a 16550A and ttyS0 is used for interaction between host terminal and my target board that is working

问题 i have a 6x6x6 rgb display on a embedded device. Do i have write my own framebufferdriver in linux for such 18bit displays? TIA! 来源： https://stackoverflow.com/questions/4783523/own-framebuffer-driver-for-a-6x6x6-rgb-display

问题 I want to create the number of minor character drivers for my module. I want to see it at the /dev/ . However, I see only one driver. What is the problem in my code? What should be the right code? #include <linux/init.h> #include <linux/module.h> /** needed by all modules **/ #include <linux/kernel.h> /** This is for KERN_ALERT **/ #include <linux/fs.h> /** for file operations **/ #include <linux/cdev.h> /** character device **/ #include <linux/device.h> /** for sys device registration in

问题 I am running kmemleak on one of my modules to find leaks, below is the result after a while. From the result, what i understand is below address are object/s address in the .ko or .o file. unreferenced object 0xffff8803c9708f10 (size 32): comm "resiter_access_i_o", pid 2320, jiffies 4294798486 hex dump (first 32 bytes): d8 8e 70 c9 03 88 ff ff a0 8e 70 c9 03 88 ff ff ..p.......p..... 68 8e 70 c9 03 88 ff ff 30 8e 70 c9 03 88 ff ff h.p.....0.p..... backtrace: [<ffffffff81516e3e>] kmemleak

问题 I tried to make a simple kernel module invalidating all tlb entries through user-level ioctl. Below is my example code [flush_tlb.c] /* * flush_tlb.c */ #include <linux/uaccess.h> #include <linux/fs.h> #include <linux/miscdevice.h> #include <linux/module.h> #include <linux/mm.h> #include <asm/tlbflush.h> #include <asm/tlb.h> #include "flush_tlb.h" MODULE_LICENSE("GPL"); static long flush_tlb_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) { int ret = 0; unsigned int size = _IOC

问题 I am studying about Linux Interrupt handling mechanism, just got doubt whether registering an interrupt handler from user-space is allowed or not? 回答1: No, interrupts are registered in the kernel and a driver / module must be loaded into kernel space to receive the interrupt. It could pass handling onto a user space daemon that hooks into the kernel module, but the something must be inserted into the kernel. 回答2: Cannot register user space interrupt handler directly. Kernel ISR indicates

问题 I have a specific question regarding using net_device module in linux kernel. Lets address this code example please. When i init my device, i call alloc_netdev and provide it with the private data size , so it will properly allocate it. Now, What happens when i call snull_cleanup when i wish to stop using this device. i see it basically free's the structure (including the private data). The question is, what if the code currently running is an inside function inside my device module which