linux 2.6.21.7
where do serial 8250 port fill its membase and mapbase fileds in
system initializing ?
I found that , when calling do_initcalls---> serial8250_init ---->
platform_driver_register--->bus_for_each_dev, system found
an device of serial 8250, which has already fill the membase and mapbase fileds.
That is to say, before serial8250_init ---->
platform_driver_register, system has create a serial device with
membase and mapbase initialized.
do_initcalls---> serial8250_init ----> platform_driver_register--->
dev = bus_for_each_dev
---> struct plat_serial8250_port *p = dev->platform_data;
/* at this point , p->membase and p->mapbase are
all assigned with proper value by system */
I searched the whole source code with keyword 'membase' , and found
the following code :
serial8250_request_std_resource:
case UPIO_MEM:
if (!up->port.mapbase)
break;
if (!request_mem_region(up->port.mapbase, size, "serial")) {
ret = -EBUSY;
break;
}
/*I guess membase is generated according to mapbase ,*
so I add some debug print here.
However, I found membase and mapbase are already initialized
before these codes. */
if (up->port.flags & UPF_IOREMAP) {
up->port.membase = ioremap(up->port.mapbase, size);
if (!up->port.membase) {
release_mem_region(up->port.mapbase, size);
ret = -ENOMEM;
}
}
So I am really confused with serial 8250
initializing----------------where do kernel apply membase and mapbase
filed to 8250 port?
Thx
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