--- /dev/null
+/*
+ * 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;
+}
Code Review / kvmfornfv.git / blobdiff