Difference between revisions of "Developer Manual/Super IO"
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Adding support for a new Super I/O chip is usually not significantly hard once you have obtained the datasheet for your target chip. Herein we shall outline the steps usally taken for a bringup. | Adding support for a new Super I/O chip is usually not significantly hard once you have obtained the datasheet for your target chip. Herein we shall outline the steps usally taken for a bringup. | ||
=== Virtual Logical Devices (LDN) === | |||
Many Super I/O's use register 0x30 of one logical device number (LDN) for more than one function enable. | |||
For example, it can be used to enable some GPIOs, GAME, MIDI etc. To overcome this issue a concept of virtual LDN has been introduced. | |||
Virtual LDN's can be used in Coreboot to map the enable bit position in register 0x30 to virtual LDN, which will just enable the functionality map to that bit. | |||
Original LDN always just switch on or off bit0 of register 0x30, however a virtual LDN is created as follows. | |||
Low [7:0] bits are used to describe the original LDN. High [10:8] bits select the position of the bit enable in the register 0x30. | |||
If LDN is 0x7 it will handle bit0 of register 0x30. If the (virtual) LDN is 0x107 it will handle bit1 of same register etc. | |||
TODO: Improvements needed here for the layman. | |||
== Source layout == | == Source layout == | ||
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*/ | */ | ||
= | A typical superio.c would look like this: | ||
#include <arch/io.h> | |||
#include <device/device.h> | |||
#include <device/pnp.h> | |||
#include <superio/conf_mode.h> | |||
#include <console/console.h> | |||
#include <stdlib.h> | |||
#include "f71869ad.h" | |||
static void f71869ad_init(device_t dev) | |||
{ | |||
= dev->chip_info; | |||
} | |||
static struct device_operations ops = { | |||
.read_resources = pnp_read_resources, | |||
, | |||
, | |||
.enable = pnp_alt_enable, | |||
.init = f71869ad_init, | |||
.ops_pnp_mode = &pnp_conf_mode_8787_aa, | |||
}; | |||
static struct pnp_info pnp_dev_info[] = { | |||
0}, }, | |||
}; | |||
static void enable_dev(device_t dev) | |||
{ | |||
} | |||
struct chip_operations superio_fintek_f71869ad_ops = { | |||
("Fintek F71869AD Super I/O") | |||
.enable_dev = enable_dev | |||
}; | |||
85 + | |||