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Re: [microblaze-uclinux] VGA controller in Microblaze

Hi John,
Thanks for your help, it helped me to understand better how to work with new devices and drivers. As you told me, I created a file xilinxfb.c in arch/microblaze/platform/common, which content is: 

#include <linux/autoconf.h>
#include <linux/init.h>
#include <linux/resource.h>
#include <linux/xilinx_devices.h>

/* Fake definitions of IRQ channels for XGPIOs that don't actually have one.
   This is not super clean, but it does allow us to use a generic
   platform_device initialiser macro - see below */

#ifndef CONFIG_XILINX_TFT_0_IRQ
#define CONFIG_XILINX_TFT_0_IRQ -1L
#endif

#ifndef CONFIG_XILINX_TFT_1_IRQ
#define CONFIG_XILINX_TFT_1_IRQ -1L
#endif

#ifndef CONFIG_XILINX_TFT_2_IRQ
#define CONFIG_XILINX_TFT_2_IRQ -1L
#endif

#ifndef CONFIG_XILINX_TFT_3_IRQ
#define CONFIG_XILINX_TFT_3_IRQ -1L
#endif

#ifndef CONFIG_XILINX_TFT_4_IRQ
#define CONFIG_XILINX_TFT_4_IRQ -1L
#endif

#ifndef CONFIG_XILINX_TFT_5_IRQ
#define CONFIG_XILINX_TFT_5_IRQ -1L
#endif

/* Generic XGPIO platform_device initialiser macro.  Sinec we can nets #ifdef
   conditionals inside macros, we have two resources for each device, but in
   non-IRQ peripherals, the resource type is set to zero, otherwise it's
   IORESOURCE_IRQ as expected.  The kernel will just ignore zero-flagged
   resources.  We waste a small number of bytes - c'est la vie*/
#define XILINX_FB_PLATFORM_INITIALISER(n) \
{								\
	.name = "xilinxfb",					\
	.id = (n),						\
	.dev.platform_data = 0,					\
	.num_resources = 2,					\
	.resource = (struct resource[]) {			\
		{						\
			.start	= CONFIG_XILINX_TFT_##n##_SPLB_BASEADDR,	\
			.end	= CONFIG_XILINX_TFT_##n##_SPLB_HIGHADDR,	\
			.flags	= IORESOURCE_IO,			\
		},							\
		{							\
			.start	= CONFIG_XILINX_TFT_##n##_IRQ,		\
			.end    = CONFIG_XILINX_TFT_##n##_IRQ,		\
			.flags  = IORESOURCE_IRQ,			\
		},							\
	},								\
}
// dev.platform_data se define como 0. En el archivo .../drivers/video/xilinxfb.c se utiliza un platform_data por defecto que define de la resolucion de la pantalla 640x480. Si aquí definimos un platform_data, utiliza estos para aplicar la resolución y si no lo definimos utiliza los que vienen por defecto. // num_resources lo definimos igual a 2, así lo hace el resto de los drivers en esta carpeta excepto xgpio (parece que este parámetro depende de si hay interrupciones?). // Será necesario definir la direccion donde se encuentra el framebuffer? (parece que no, debería buscarla usando baseaddr). 

static struct platform_device xilinx_fb_device[]= {
#ifdef CONFIG_XILINX_TFT_0_INSTANCE
XILINX_FB_PLATFORM_INITIALISER(0),
#endif
#ifdef CONFIG_XILINX_TFT_1_INSTANCE
XILINX_FB_PLATFORM_INITIALISER(1),
#endif
#ifdef CONFIG_XILINX_TFT_2_INSTANCE
XILINX_FB_PLATFORM_INITIALISER(2),
#endif
#ifdef CONFIG_XILINX_TFT_3_INSTANCE
XILINX_FB_PLATFORM_INITIALISER(3),
#endif
#ifdef CONFIG_XILINX_TFT_4_INSTANCE
XILINX_FB_PLATFORM_INITIALISER(4),
#endif
#ifdef CONFIG_XILINX_TFT_5_INSTANCE
XILINX_FB_PLATFORM_INITIALISER(5),
#endif
};

static int __init xilinx_fb_platform_init(void)
{
	int i;

	for(i=0;i<ARRAY_SIZE(xilinx_fb_device); i++)
		platform_device_register(&xilinx_fb_device[i]);

	return 0;
}

device_initcall(xilinx_fb_platform_init);


As a result, now I have a xilinxfb device:

    # ls /sys/bus/platform/devices/
    i8042          uartlite.0     xilinx_gpio.0  xilinx_gpio.1  xilinxfb.0
However this device is not assigned to fb0. I receive the following message when booting the board: 

xilinxfb xilinxfb.0: regs: phys=86e00000, virt=86e00000
xilinxfb xilinxfb.0: fb: phys=8fc00000, virt=8fc00000, size=1e0000
However there are no messages about the framebuffer. Moreover, when I try to see the I/O memory space I obtain the following: 

    # cat /proc/iomem
    81400000-8140ffff : xilinx_gpio.0
      81400000-8140ffff : xilinx_gpio
    81420000-8142ffff : xilinx_gpio.1
      81420000-8142ffff : xilinx_gpio
    84000000-8400ffff : uartlite.0
      84000000-8400000f : uartlite
    86e00000-86e00007 : xilinxfb
As you can see, there is no memory assigned to xilinxfb.o. I am surely missing some steps when creating the framebuffer but I am not able to see where is the error. Do you have any hint about what I am not doing right? 

Thanks a lot for your kind help John.

Regards,

Pablo Colodron



John Williams escribió:

Hi Pablo,

On Wed, Mar 25, 2009 at 8:50 PM,  <pcolodron@xxxxxxxx> wrote:

Hi Inaki,

That is what I was checking just right now :) I have found out that although
it enters in function 'platform_driver_register', it does not enter in
function 'xilinxfb_platform_probe', which is the one that initialize the
framebuffer. I don't know why this happens but I'll try to figure it out...
Thanks a lot for your help Inaki. I'll let you know my progress.


The problem is that you have not registered a platform device - that
is the kernel doesn't know you have a xilinx_fb device in the system,
so it never calls the _probe() function.

To do this, look in arch/microblaze/platform/common - you need to
create a file called xilinxfb.c here.  Link it in to the Makefile of
this directory.

This code must create a platform_device structure, and then call
platform_device_register() on that object.

There are other examples in this same directory for other devices -
e.g. xilinx_spi.c.  The pattern should be clear.

Regards,

John
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