"Android Deep Exploration" (Vol. 1) HAL and Driver development Seventh chapter experience

-Driven porting.

In the Drivers/char directory, we create a driver file mini2440_leds.c, which reads as follows:

<span style= "FONT-SIZE:18PX;" > #include <linux/miscdevice.h>
#include <linux/delay.h>
#include <asm/irq.h>
#include <mach/regs-gpio.h>
#include <mach/hardware.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/ioctl.h>
#include <linux/cdev.h>
#include <linux/string.h>
#include <linux/list.h>
#include <linux/pci.h>
#include <linux/gpio.h>
#include <asm/uaccess.h>
#include <asm/atomic.h>
#include <asm/unistd.h>
#define DEVICE_NAME "LEDs" <span style= "Color:rgb (51, 102, 255);" >//device Name (/dev/leds</span>)
<span style= "Color:rgb (51, 102, 255); List of >//led corresponding GPIO ports
</span>static unsigned long led_table [] = {
S3C2410_GPB (5),
S3C2410_GPB (6),
S3C2410_GPB (7),
S3C2410_GPB (8),
};
<span style= "Color:rgb (51, 102, 255); >//led The status list that the corresponding port will output
</span>static unsigned int led_cfg_table [] = {
S3c2410_gpio_output,
S3c2410_gpio_output,
S3c2410_gpio_output,
S3c2410_gpio_output,
};
<span style= "Color:rgb (51, 102, 255); Implementation of >/*IOCTL function
* The application/user layer will pass parameters to the kernel via the IOCTL function to control the output status of the LEDs
*/
</span>static int Sbc2440_leds_ioctl (
struct Inode *inode,
struct file *file,
unsigned int cmd,
unsigned long arg)
{
switch (cmd) {
Case 0:
Case 1:
if (Arg > 4) {
Return-einval;
}
<span style= "Color:rgb (51, 102, 255); >//the S3c2410_gpio_setpin function to set the port storage of the LEDs according to the parameters (inversion) passed by the application/user layer
Device,</span>
S3c2410_gpio_setpin (Led_table[arg],!cmd);
return 0;
Default:
Return-einval;
}
}
<span style= "Color:rgb (51, 102, 255); >/*
* Device function operation set, where only the IOCTL function, usually also read, write, open, close, etc., because this led driver has been
* Registered as Misc device, so you can not open/close
*/
</span>static struct File_operations dev_fops = {
. Owner = This_module,
. IOCTL = Sbc2440_leds_ioctl,
};
<span style= "Color:rgb (51, 102, 255); ">/*
* Register the LED driver as a misc device
*/
</span>static struct Miscdevice misc = {
. minor = Misc_dynamic_minor,//dynamic device number
. Name = Device_name,
. FoPs = &dev_fops,
};
<span style= "Color:rgb (51, 102, 255); >/*
* Initialization of the device
*/
</span>static int __init dev_init (void)
{
int ret;
int i;
For (i = 0; i < 4; i++) {
<span style= "Color:rgb (51, 102, 255); >//Setting the port register for the LEDs is output
</span>s3c2410_gpio_cfgpin (Led_table[i], led_cfg_table[i]);
<span style= "Color:rgb (51, 102, 255); >//set the LED corresponding to the port register for the low-level output, after the module is loaded, four LEDs should be all glow
Status </span>
S3c2410_gpio_setpin (Led_table[i], 0);
}
ret = Misc_register (&MISC); <span style= "Color:rgb (51, 102, 255);" >//Registration Equipment </span>
PRINTK (device_name "\tinitialized\n"); <span style= "Color:rgb (51, 102, 255);" >//Print initialization Information </span>
return ret;
}
static void __exit dev_exit (void)
{
Misc_deregister (&MISC);
}
Module_init (dev_init); <span style= "Color:rgb (51, 51, 255);" >//module initialization, which is useful only when loading with the Insmod/podprobe command, will not be called if the device is not loaded by module mode
</span>module_exit (Dev_exit<span style= "" >) <span style= "Color:rgb (51, 102, 255);" >//unload the module, when the device is loaded through the module mode, it can be uninstalled by the Rmmod command, which will be called
</span></span><span style= "" > Number
</span>module_license ("GPL"); <span style= "Color:rgb (51, 102, 255);" >//Copyright Information
</span>module_author ("Friendlyarm Inc."); <span style= "Color:rgb (51, 102, 255); ">//Developer Info </span></span>

Next, we add the LED device kernel configuration option, open the Drivers/char/kconfig file, add the following red section:
Config Devkmem
BOOL "/DEV/KMEM Virtual device Support"
Default Y
Help
Say Y here if you want to support THE/DEV/KMEM device. The
/dev/kmem device is rarely used and can be used for certain
Kind of kernel debugging operations.
When in doubt, say "N".

Config leds_mini2440
TriState "LED support for Mini2440 GPIO LEDs"
Depends on mach_mini2440
Default Y if mach_mini2440

Help
This option enables the support for LEDs connected to GPIO lines
On Mini2440 boards.
Config MINI2440_ADC
bool "ADC driver for Friendlyarm Mini2440 development boards"
depends on mach_mini2440
default y if mach_mini2440
Help
This is the ADC driver for friendlyarm Mini2440 development boards
notes:the touch-screen-driver required this option
Next, according to the driver's configuration definition, the corresponding drive target file into the kernel, open the Linux-2.6.32.2/drivers/char/makefile file, add the following red part of the content:
obj-$ (CONFIG_JS_RTC) + = JS-RTC.O
js-rtc-y = RTC.O
obj-$ (config_leds_mini2440) + = MINI2440_LEDS.O

obj-$ (CONFIG_MINI2440_ADC) + = MINI2440_ADC.O
# Files generated that shall is removed upon make clean
Clean-files: = consolemap_deftbl.c defkeymap.c
In this way, we will add the LED driver in the kernel.

"Android Deep Exploration" (Vol. 1) HAL and Driver development Seventh chapter experience