I flashed Linaro on Snapdragon board and tried to execute the make but it was failed with following error msg. But it is working fine in the ubuntu.
make -C /lib/modules/4.0.0-linaro-lt-qcom/build M=/home/linaro/Downloads modules
make[1]: Entering directory '/usr/src/linux-headers-4.0.0-linaro-lt-qcom'
CC [M] /home/linaro/Downloads/lcd.o
/home/linaro/Downloads/lcd.c:90:12: warning: initialization from incompatible pointer type
.write = writeToLCD,
^
/home/linaro/Downloads/lcd.c:90:12: warning: (near initialization for ‘fops.write’)
/home/linaro/Downloads/lcd.c:81:16: warning: ‘lcd_read’ declared ‘static’ but never defined [-Wunused-function]
static ssize_t lcd_read(struct file , char *, size_t, loff_t *); / reading data from lcd */
^
/home/linaro/Downloads/lcd.c:82:16: warning: ‘lcd_write’ declared ‘static’ but never defined [-Wunused-function]
static ssize_t lcd_write(struct file , const char *, size_t, loff_t *);/ write data to lcd */
^
scripts/basic/fixdep: 1: scripts/basic/fixdep: Syntax error: "(" unexpected
scripts/Makefile.build:264: recipe for target '/home/linaro/Downloads/lcd.o' failed
make[2]: *** [/home/linaro/Downloads/lcd.o] Error 2
Makefile:1390: recipe for target 'module/home/linaro/Downloads' failed
make[1]: *** [_module_/home/linaro/Downloads] Error 2
make[1]: Leaving directory '/usr/src/linux-headers-4.0.0-linaro-lt-qcom'
Makefile:6: recipe for target 'all' failed
make: *** [all] Error 2
我们在snapdragon主板上闪现的图像是有关此信息的linaro信息，我们在96boards.com上提供信息 http://www.96boards.org/blog/part-1-home-surveillance-project-96boards/
这是为lcd.c驱动程序代码编写的makefile。下面的lcd.c代码是可用的，你可以看看该代码，并帮助我解决这个问题。
obj-m:=lcd.o
KDIR:=/lib/modules/$(shell uname -r)/build
PWD:=$(shell pwd)
all:
$(MAKE) -C $(KDIR) M=$(PWD) modules
clean:
$(MAKE) -C $(KDIR) M=$(PWD) clean
@rm -f Module.symvers app
This is lcd.c driver code when i want to execute make it is not working properly it is giving the error which is mentioned above.
here i am using the Grove lcd RGB backlight. the below link is lcd link
https://www.seeedstudio.com/Grove-Serial-LCD-p-773.html.And if i m directly trying to insert the .ko file which generated on other system it is giving the insmod failed could not insert module & invalid module format.
/* Header files */
#include <linux/module.h> /* module_init,module_exit */
#include <linux/fs.h> /* struct file_operations */
#include <linux/cdev.h> /* cdev_alloc,cdev_add */
#include <linux/device.h> /* device_create,class_create */
#include <linux/slab.h> /* for kmalloc,kfree */
#include <linux/uaccess.h>
#include <linux/gfp.h> /* for kmalloc function */
/*Project specific include files*/
#include <linux/i2c.h> /* for I2c */
#include <linux/i2c-dev.h> /* for I2C */
/* Macros */
#define FIRST_MINOR 10 /* first minor number */
#define NR_DEVS 1 /* Number of device numbers */
/*new*/
#define LCD_SLAVE 0x3E
#define BUS 0x00
#define REG_MODE1 0x00
#define REG_MODE2 0x01
#define REG_OUTPUT 0x08
//commands
#define LCD_CLEARDISPLAY 0x01
#define LCD_RETURNHOME 0x02
#define LCD_ENTRYMODESET 0x04
#define LCD_DISPLAYCONTROL 0x08
#define LCD_CURSORSHIFT 0x10
#define LCD_FUNCTIONSET 0x20
#define LCD_SETCGRAMADDR 0x40
#define LCD_SETDDRAMADDR 0x80
//display entry mode
#define LCD_ENTRYRIGHT 0x00
#define LCD_ENTRYLEFT 0x02
#define LCD_ENTRYSHIFTINCREMENT 0x01
#define LCD_ENTRYSHIFTDECREMENT 0x00
//display on/off control
#define LCD_DISPLAYON 0x04
#define LCD_DISPLAYOFF 0x00
#define LCD_CURSORON 0x02
#define LCD_CURSOROFF 0x00
#define LCD_BLINKON 0x01
#define LCD_BLINKOFF 0x00
// flags for display/cursor shift
#define LCD_DISPLAYMOVE 0x08
#define LCD_CURSORMOVE 0x00
#define LCD_MOVERIGHT 0x04
#define LCD_MOVELEFT 0x00
// flags for function set
#define LCD_8BITMODE 0x10
#define LCD_2LINE 0x08
//variables
char * lcd_text_; //variable to store user space lcd_text data
//function definitions
s32 writeByteRegister(struct i2c_client *client,u8 reg, u8 value);
void clearLCD(struct i2c_client *client);
void writeToLCD(struct i2c_client *client, const char *c);
void initLCD(struct i2c_client *client);
size_t write(struct file *, const char *buf, size_t c);
/* Function Declarations for syscall definitions */
int lcd_Open(struct inode *inode, struct file *filep);
int lcd_Release(struct inode *in, struct file *fp);
static ssize_t lcd_read(struct file *, char *, size_t, loff_t *); /* reading data from lcd */
static ssize_t lcd_write(struct file *, const char *, size_t, loff_t *);/* write data to lcd */
struct i2c_msg msg[1]; /* structure for each message */
struct i2c_msg msg1[1]; /* structure for each message */
struct i2c_client client1;
/* @file_operations - Operations which can be performed with the device */
struct file_operations fops = {
.owner = THIS_MODULE,
.write = writeToLCD,
};
/* function declarations of i2c_driver */
static int lcd_probe(struct i2c_client *client, const struct i2c_device_id *id);
static int lcd_remove(struct i2c_client *client);
/* list of devices supported by my driver */
static struct i2c_device_id lcd_id[] = {
{ "lcd_i2c", 0 },
};
static struct i2c_driver lcd_driver = {
.driver.name = "lcd_i2c",
.probe = lcd_probe,
.remove = lcd_remove,
.id_table = lcd_id,
};
/*
* lcd_probe - probe function of driver
* @client - pointer to structure client which has the address, algorithm followed by the device
* @id - pointer to structure i2c_device which is maintained for the driver module
*
* Description - getting the address of the lcd device connected
*
* return value - 0
*/
static int lcd_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
printk(KERN_ALERT "In probe function\n");
client1.addr = client->addr;
client1.adapter = client->adapter;
initLCD(&client1);
writeToLCD(&client1,"nice!");
return 0;
}
s32 writeByteRegister(struct i2c_client *client,u8 reg, u8 value)
{
s32 res = -1;
res = i2c_smbus_write_byte_data(client, reg, value);
if (res < 0)
{
/* ERROR HANDLING: i2c transaction failed */
//printk("%s: Error reading reg: 0x%x, code:%d \n",TAG,reg,res);
}
return res;
}
void clearLCD(struct i2c_client *client)
{
writeByteRegister(client, 0x00, LCD_CLEARDISPLAY );
}
/* size_t write(struct file *, const char *buf, size_t c)
{
writeToLCD(&client1, buf);
}
*/
void writeToLCD(struct i2c_client *client, const char *c)
{
int ascii_val=0;
int i;
for(i = 0 ; i < 2; i++)
{
ascii_val = (int)c[i];
writeByteRegister(client, 0x40, ascii_val);
}
}
void initLCD(struct i2c_client *client)
{
writeByteRegister(client, 0x00, LCD_FUNCTIONSET | LCD_2LINE );
//msleep(10);
writeByteRegister(client, 0x00,LCD_DISPLAYCONTROL | LCD_DISPLAYON
| LCD_CURSORON | LCD_BLINKON );
//msleep(10);
writeByteRegister(client, 0x00, LCD_CLEARDISPLAY );
//msleep(40);
writeByteRegister(client, 0x00,LCD_ENTRYMODESET | LCD_ENTRYLEFT
| LCD_ENTRYSHIFTDECREMENT );
}
/*
* lcd_remove - remove function of driver
* @client - pointer to structure client which has the address, algorithm followed by the device
*
* return value - 0
*/
static int lcd_remove(struct i2c_client *client)
{
printk(KERN_ALERT "In remove function\n");
return 0;
}
/* Global variables */
char *devname; /* contains device name */
int majNo; /* holds major number */
static dev_t lcd_dev; /* encodes major number and minor number */
struct cdev *lcd_cdev; /* holds character device driver descriptor */
static int val; /* for i2c_driver structure probe */
/* To accept input from the command line */
module_param(devname, charp, 0);
/* class and device structures */
static struct class *lcd_char_class;
static struct device *lcd_char_device;
/*
* myRelease - close function of the pseudo driver
* @in - pointer to structure inode
* @fp - pointer to structure file
*
* return value - 0
*/
int lcd_Release(struct inode *in, struct file *fp)
{
printk(KERN_INFO "File released \n");
return 0;
}
/*
* myinit - init function of the kernel module
*
* Description - registering the driver
* return value - 0
*/
static int __init lcd_init(void)
{
int status; /* checking the return value for alloc_chrdev_region */
int ret = 0; /* checking error values */
/* Allocating Device Numbers */
status = alloc_chrdev_region(&lcd_dev, FIRST_MINOR, NR_DEVS, devname);
if (status < 0) {
printk(KERN_NOTICE "Device numbers allocation failed: %d \n", status);
goto err;
}
printk(KERN_INFO "Major number allocated = %d \n", MAJOR(lcd_dev));
lcd_cdev = cdev_alloc(); /* Allocate memory for my_cdev */
if (lcd_cdev == NULL ) {
printk(KERN_ERR "cdev_alloc failed \n");
goto err_cdev_alloc;
}
cdev_init(lcd_cdev, &fops); /* Initialize my_cdev with fops */
lcd_cdev->owner = THIS_MODULE;
status = cdev_add(lcd_cdev, lcd_dev, NR_DEVS); /* Add my_cdev to the list */
if (status) {
printk(KERN_ERR "cdev_add failed \n");
goto err_cdev_add;
}
/* Create a class and an entry in sysfs */
lcd_char_class = class_create(THIS_MODULE, devname);
if (IS_ERR(lcd_char_class)) {
printk(KERN_ERR "class_create() failed \n");
goto err_class_create;
}
/* create mychar_device ni sysfs and an device entry will be made in /dev directory */
lcd_char_device = device_create(lcd_char_class, NULL, lcd_dev, NULL, devname);
if (IS_ERR(lcd_char_device)) {
printk(KERN_ERR "device_create() failed \n");
goto err_device_create;
}
val = i2c_add_driver(&lcd_driver);
if (val) {
printk("Registering I2C driver failed, errno is %d\n", val);
err_device_create:
class_destroy(lcd_char_class);
err_class_create:
cdev_del(lcd_cdev);
err_cdev_add:
kfree(lcd_cdev);
err_cdev_alloc:
unregister_chrdev_region(lcd_dev, NR_DEVS);
err:
return ret;
}
return 0;
}
/*
* myexit - cleanup function of the kernel module
*
* Description - unregister the driver
*/
static void __exit lcd_exit(void)
{
printk(KERN_INFO "exiting the character Driver \n");
device_destroy(lcd_char_class, lcd_dev);
class_destroy(lcd_char_class);
cdev_del(lcd_cdev);
unregister_chrdev_region(lcd_dev, NR_DEVS);
i2c_del_driver(&lcd_driver);
return ;
}
module_init(lcd_init);
module_exit(lcd_exit);
MODULE_LICENSE("GPL");