blob: 7d9fac72337fc329ac12d2c80ad21f03b9e8fe7e [file] [log] [blame]
/*
* Copyright (c) 2012 The Chromium OS Authors.
* SPDX-License-Identifier: GPL-2.0+
*/
/*
* This is a GPIO driver for Intel ICH6 and later. The x86 GPIOs are accessed
* through the PCI bus. Each PCI device has 256 bytes of configuration space,
* consisting of a standard header and a device-specific set of registers. PCI
* bus 0, device 31, function 0 gives us access to the chipset GPIOs (among
* other things). Within the PCI configuration space, the GPIOBASE register
* tells us where in the device's I/O region we can find more registers to
* actually access the GPIOs.
*
* PCI bus/device/function 0:1f:0 => PCI config registers
* PCI config register "GPIOBASE"
* PCI I/O space + [GPIOBASE] => start of GPIO registers
* GPIO registers => gpio pin function, direction, value
*
*
* Danger Will Robinson! Bank 0 (GPIOs 0-31) seems to be fairly stable. Most
* ICH versions have more, but the decoding the matrix that describes them is
* absurdly complex and constantly changing. We'll provide Bank 1 and Bank 2,
* but they will ONLY work for certain unspecified chipsets because the offset
* from GPIOBASE changes randomly. Even then, many GPIOs are unimplemented or
* reserved or subject to arcane restrictions.
*/
#include <common.h>
#include <pci.h>
#include <asm/gpio.h>
#include <asm/io.h>
/* Where in config space is the register that points to the GPIO registers? */
#define PCI_CFG_GPIOBASE 0x48
#define NUM_BANKS 3
/* Within the I/O space, where are the registers to control the GPIOs? */
static struct {
u8 use_sel;
u8 io_sel;
u8 lvl;
} gpio_bank[NUM_BANKS] = {
{ 0x00, 0x04, 0x0c }, /* Bank 0 */
{ 0x30, 0x34, 0x38 }, /* Bank 1 */
{ 0x40, 0x44, 0x48 } /* Bank 2 */
};
static pci_dev_t dev; /* handle for 0:1f:0 */
static u32 gpiobase; /* offset into I/O space */
static int found_it_once; /* valid GPIO device? */
static u32 lock[NUM_BANKS]; /* "lock" for access to pins */
static int bad_arg(int num, int *bank, int *bitnum)
{
int i = num / 32;
int j = num % 32;
if (num < 0 || i > NUM_BANKS) {
debug("%s: bogus gpio num: %d\n", __func__, num);
return -1;
}
*bank = i;
*bitnum = j;
return 0;
}
static int mark_gpio(int bank, int bitnum)
{
if (lock[bank] & (1UL << bitnum)) {
debug("%s: %d.%d already marked\n", __func__, bank, bitnum);
return -1;
}
lock[bank] |= (1 << bitnum);
return 0;
}
static void clear_gpio(int bank, int bitnum)
{
lock[bank] &= ~(1 << bitnum);
}
static int notmine(int num, int *bank, int *bitnum)
{
if (bad_arg(num, bank, bitnum))
return -1;
return !(lock[*bank] & (1UL << *bitnum));
}
static int gpio_init(void)
{
u8 tmpbyte;
u16 tmpword;
u32 tmplong;
/* Have we already done this? */
if (found_it_once)
return 0;
/* Where should it be? */
dev = PCI_BDF(0, 0x1f, 0);
/* Is the device present? */
pci_read_config_word(dev, PCI_VENDOR_ID, &tmpword);
if (tmpword != PCI_VENDOR_ID_INTEL) {
debug("%s: wrong VendorID\n", __func__);
return -1;
}
pci_read_config_word(dev, PCI_DEVICE_ID, &tmpword);
debug("Found %04x:%04x\n", PCI_VENDOR_ID_INTEL, tmpword);
/*
* We'd like to validate the Device ID too, but pretty much any
* value is either a) correct with slight differences, or b)
* correct but undocumented. We'll have to check a bunch of other
* things instead...
*/
/* I/O should already be enabled (it's a RO bit). */
pci_read_config_word(dev, PCI_COMMAND, &tmpword);
if (!(tmpword & PCI_COMMAND_IO)) {
debug("%s: device IO not enabled\n", __func__);
return -1;
}
/* Header Type must be normal (bits 6-0 only; see spec.) */
pci_read_config_byte(dev, PCI_HEADER_TYPE, &tmpbyte);
if ((tmpbyte & 0x7f) != PCI_HEADER_TYPE_NORMAL) {
debug("%s: invalid Header type\n", __func__);
return -1;
}
/* Base Class must be a bridge device */
pci_read_config_byte(dev, PCI_CLASS_CODE, &tmpbyte);
if (tmpbyte != PCI_CLASS_CODE_BRIDGE) {
debug("%s: invalid class\n", __func__);
return -1;
}
/* Sub Class must be ISA */
pci_read_config_byte(dev, PCI_CLASS_SUB_CODE, &tmpbyte);
if (tmpbyte != PCI_CLASS_SUB_CODE_BRIDGE_ISA) {
debug("%s: invalid subclass\n", __func__);
return -1;
}
/* Programming Interface must be 0x00 (no others exist) */
pci_read_config_byte(dev, PCI_CLASS_PROG, &tmpbyte);
if (tmpbyte != 0x00) {
debug("%s: invalid interface type\n", __func__);
return -1;
}
/*
* GPIOBASE moved to its current offset with ICH6, but prior to
* that it was unused (or undocumented). Check that it looks
* okay: not all ones or zeros, and mapped to I/O space (bit 0).
*/
pci_read_config_dword(dev, PCI_CFG_GPIOBASE, &tmplong);
if (tmplong == 0x00000000 || tmplong == 0xffffffff ||
!(tmplong & 0x00000001)) {
debug("%s: unexpected GPIOBASE value\n", __func__);
return -1;
}
/*
* Okay, I guess we're looking at the right device. The actual
* GPIO registers are in the PCI device's I/O space, starting
* at the offset that we just read. Bit 0 indicates that it's
* an I/O address, not a memory address, so mask that off.
*/
gpiobase = tmplong & 0xfffffffe;
/* Finally. These are the droids we're looking for. */
found_it_once = 1;
return 0;
}
int gpio_request(unsigned num, const char *label /* UNUSED */)
{
u32 tmplong;
int i = 0, j = 0;
/* Is the hardware ready? */
if (gpio_init())
return -1;
if (bad_arg(num, &i, &j))
return -1;
/*
* Make sure that the GPIO pin we want isn't already in use for some
* built-in hardware function. We have to check this for every
* requested pin.
*/
tmplong = inl(gpiobase + gpio_bank[i].use_sel);
if (!(tmplong & (1UL << j))) {
debug("%s: gpio %d is reserved for internal use\n", __func__,
num);
return -1;
}
return mark_gpio(i, j);
}
int gpio_free(unsigned num)
{
int i = 0, j = 0;
if (notmine(num, &i, &j))
return -1;
clear_gpio(i, j);
return 0;
}
int gpio_direction_input(unsigned num)
{
u32 tmplong;
int i = 0, j = 0;
if (notmine(num, &i, &j))
return -1;
tmplong = inl(gpiobase + gpio_bank[i].io_sel);
tmplong |= (1UL << j);
outl(gpiobase + gpio_bank[i].io_sel, tmplong);
return 0;
}
int gpio_direction_output(unsigned num, int value)
{
u32 tmplong;
int i = 0, j = 0;
if (notmine(num, &i, &j))
return -1;
tmplong = inl(gpiobase + gpio_bank[i].io_sel);
tmplong &= ~(1UL << j);
outl(gpiobase + gpio_bank[i].io_sel, tmplong);
return 0;
}
int gpio_get_value(unsigned num)
{
u32 tmplong;
int i = 0, j = 0;
int r;
if (notmine(num, &i, &j))
return -1;
tmplong = inl(gpiobase + gpio_bank[i].lvl);
r = (tmplong & (1UL << j)) ? 1 : 0;
return r;
}
int gpio_set_value(unsigned num, int value)
{
u32 tmplong;
int i = 0, j = 0;
if (notmine(num, &i, &j))
return -1;
tmplong = inl(gpiobase + gpio_bank[i].lvl);
if (value)
tmplong |= (1UL << j);
else
tmplong &= ~(1UL << j);
outl(gpiobase + gpio_bank[i].lvl, tmplong);
return 0;
}