FL2440 driver addition (3) LCD driver addition study notes

FL2440 LCD built-in controller, 320*240 TFT LCD.

Two add-drive modes summarized by self-understanding:

Adding drivers in non-platform mode:

Load the driver:

1. Hardware initialization, memory application, and address mapping

2. Allocate device number and structure

3. Register the device

Uninstall the driver:

1. Release memory

2. Release the structure and return the device number

3. Unregister the device

Add driver by platform bus mode (mainstream mode):

1. Write a device chain

struct platform_device

{

const chat *name;

u32 id;

struct device dev;

u32 num_resources;

struct resources * resources;

};

2. Write the drive chain

static struct platform_driver

{

int (*probe)( struct platform_device*), //detection function

int (*remove)( structplatform_device*), //delete function

……

struct device_driver driver;

};

3. Register the device in the device chain and register the driver in the driver chain

int __init xxx_init()

{

.....

platform_device_register();

platform_driver_register();

.....

}

4. Reversely, cancel the driver in the driver chain and cancel the device in the device chain

void __exit  xxx_exit()

{

.....

platform_driver_unregister();

platform_device_unregister();

.....

}

Start adding LCD driver: kernel version linux-3.8.0

1. Modify the relevant information platform data in arch/arm/mach-s3c24xx/mach-smdk2440.c

/* LCD driver info */

static struct s3c2410fb_display smdk2440_lcd_cfg __initdata = {

.lcdcon5   = S3C2410_LCDCON5_FRM565|

S3C2410_LCDCON5_INVVLINE |

S3C2410_LCDCON5_INVVFRAME |

S3C2410_LCDCON5_PWREN |

S3C2410_LCDCON5_HWSWP,

.type      = S3C2410_LCDCON1_TFT,

.width     = 320,

.height    = 240,

.pixclock  = 111111, /* HCLK 60 MHz, divisor 10 */

.xres = 480,

.yres = 272,

.bpp       = 16,

.left_margin    = 38,

.right_margin   = 20,

.hsync_len = 30,

.upper_margin   = 15,

.lower_margin   = 12,

.vsync_len = 3,

};

static struct s3c2410fb_mach_info smdk2440_fb_info  __initdata = {

.displays  = &smdk2440_lcd_cfg,

.num_displays   = 1,

.default_display = 0,

#if 0
/* currently setup by downloader */
.gpccon     = 0xaa940659,
.gpccon_mask    = 0xffffffff,
.gpcup      = 0x0000ffff,
.gpcup_mask = 0xffffffff,
.gpdcon     = 0xaa84aaa0,
.gpdcon_mask    = 0xffffffff,
.gpdup      = 0x0000faff,
.gpdup_mask = 0xffffffff,
#endif

.lpcsel    = ((0xCE6) & ~7) | 1<<1,

};

2. Since the LCD device and platform addition functions have been defined in arch/arm/plat-samsung/devs.c, as follows

/* LCD Controller */

#ifdef CONFIG_PLAT_S3C24XX

static struct resource s3c_lcd_resource[]= {

[0] = DEFINE_RES_MEM(S3C24XX_PA_LCD, S3C24XX_SZ_LCD),

[1] = DEFINE_RES_IRQ(IRQ_LCD),

};

struct platform_device s3c_device_lcd= {

.name      = "s3c2410-lcd",

.id    = -1,

.num_resources  = ARRAY_SIZE(s3c_lcd_resource),

.resource  = s3c_lcd_resource,

.dev       = {

.dma_mask       = &samsung_device_dma_mask,

.coherent_dma_mask  = DMA_BIT_MASK(32),

}

};

//Platform add function

void __init s3c24xx_fb_set_platdata(structs3c2410fb_mach_info *pd)

{

struct s3c2410fb_mach_info *npd;

npd = s3c_set_platdata(pd, sizeof(*npd), &s3c_device_lcd);

if (npd) {

npd->displays =kmemdup(pd->displays,

sizeof(struct s3c2410fb_display) * npd->num_displays,

GFP_KERNEL);

if (!npd->displays)

printk(KERN_ERR "no memory forLCD display data");

} else {

printk(KERN_ERR "no memory for LCDplatform datan");

}

}

#endif /*CONFIG_PLAT_S3C24XX */

So in arch/arm/mach-s3c24xx/mach-smdk2440.c just register the device:

static struct platform_device *smdk2440_devices[] __initdata = {

&s3c_device_ohci,

&s3c_device_lcd,

&s3c_device_wdt,

&s3c_device_i2c0,

&s3c_device_iis,

&s3c_device_dm9000,

&s3c_device_adc,

&s3c_device_ts,

&s3c_device_rtc,

&globalfifo_device

};

Add to the device chain by calling smdk2440_machine_init,

static void __init smdk2440_machine_init(void)

{

// Call this function to save the LCD hardware information defined above into the platform data

s3c24xx_fb_set_platdata(&smdk2440_fb_info);

s3c_i2c0_set_platdata(NULL);

platform_add_devices(smdk2440_devices,ARRAY_SIZE(smdk2440_devices));

smdk_machine_init();

}

Tracing the platform_add_devices function, it actually calls the platform_device_register and platform_device_unregister functions, as follows:

Defined in drivers/base/platform.c:

int platform_add_devices(struct platform_device **devs, int num)
{
int i, ret = 0;

for (i = 0; i < num; i++) {
ret = platform_device_register(devs[i]);
if (ret) {
while (--i >= 0)
platform_device_unregister(devs[i]);
break;
}
}

return ret;
}
EXPORT_SYMBOL_GPL(platform_add_devices);