linux/drivers/gpu/drm/i915/display/intel_vga.c

// SPDX-License-Identifier: MIT
/*
 * Copyright © 2019 Intel Corporation
 */

#include <linux/delay.h>
#include <linux/pci.h>
#include <linux/vgaarb.h>

#include <drm/drm_device.h>
#include <drm/drm_print.h>
#include <drm/intel/i915_drm.h>
#include <video/vga.h>

#include "intel_de.h"
#include "intel_display.h"
#include "intel_display_types.h"
#include "intel_vga.h"
#include "intel_vga_regs.h"

static i915_reg_t intel_vga_cntrl_reg(struct intel_display *display)
{
	if (display->platform.valleyview || display->platform.cherryview)
		return VLV_VGACNTRL;
	else if (DISPLAY_VER(display) >= 5)
		return CPU_VGACNTRL;
	else
		return VGACNTRL;
}

static bool has_vga_pipe_sel(struct intel_display *display)
{
	if (display->platform.i845g ||
	    display->platform.i865g)
		return false;

	if (display->platform.valleyview ||
	    display->platform.cherryview)
		return true;

	return DISPLAY_VER(display) < 7;
}

/* Disable the VGA plane that we never use */
void intel_vga_disable(struct intel_display *display)
{
	struct pci_dev *pdev = to_pci_dev(display->drm->dev);
	i915_reg_t vga_reg = intel_vga_cntrl_reg(display);
	enum pipe pipe;
	u32 tmp;
	u8 sr1;

	tmp = intel_de_read(display, vga_reg);
	if (tmp & VGA_DISP_DISABLE)
		return;

	if (display->platform.cherryview)
		pipe = REG_FIELD_GET(VGA_PIPE_SEL_MASK_CHV, tmp);
	else if (has_vga_pipe_sel(display))
		pipe = REG_FIELD_GET(VGA_PIPE_SEL_MASK, tmp);
	else
		pipe = PIPE_A;

	drm_dbg_kms(display->drm, "Disabling VGA plane on pipe %c\n",
		    pipe_name(pipe));

	/* WaEnableVGAAccessThroughIOPort:ctg,elk,ilk,snb,ivb,vlv,hsw */
	vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO);
	outb(0x01, VGA_SEQ_I);
	sr1 = inb(VGA_SEQ_D);
	outb(sr1 | VGA_SR01_SCREEN_OFF, VGA_SEQ_D);
	vga_put(pdev, VGA_RSRC_LEGACY_IO);
	udelay(300);

	intel_de_write(display, vga_reg, VGA_DISP_DISABLE);
	intel_de_posting_read(display, vga_reg);
}

void intel_vga_reset_io_mem(struct intel_display *display)
{
	struct pci_dev *pdev = to_pci_dev(display->drm->dev);

	/*
	 * After we re-enable the power well, if we touch VGA register 0x3d5
	 * we'll get unclaimed register interrupts. This stops after we write
	 * anything to the VGA MSR register. The vgacon module uses this
	 * register all the time, so if we unbind our driver and, as a
	 * consequence, bind vgacon, we'll get stuck in an infinite loop at
	 * console_unlock(). So make here we touch the VGA MSR register, making
	 * sure vgacon can keep working normally without triggering interrupts
	 * and error messages.
	 */
	vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO);
	outb(inb(VGA_MIS_R), VGA_MIS_W);
	vga_put(pdev, VGA_RSRC_LEGACY_IO);
}

static int intel_gmch_vga_set_state(struct intel_display *display, bool enable_decode)
{
	struct pci_dev *pdev = to_pci_dev(display->drm->dev);
	unsigned int reg = DISPLAY_VER(display) >= 6 ? SNB_GMCH_CTRL : INTEL_GMCH_CTRL;
	u16 gmch_ctrl;

	if (pci_bus_read_config_word(pdev->bus, PCI_DEVFN(0, 0), reg, &gmch_ctrl)) {
		drm_err(display->drm, "failed to read control word\n");
		return -EIO;
	}

	if (!!(gmch_ctrl & INTEL_GMCH_VGA_DISABLE) == !enable_decode)
		return 0;

	if (enable_decode)
		gmch_ctrl &= ~INTEL_GMCH_VGA_DISABLE;
	else
		gmch_ctrl |= INTEL_GMCH_VGA_DISABLE;

	if (pci_bus_write_config_word(pdev->bus, PCI_DEVFN(0, 0), reg, gmch_ctrl)) {
		drm_err(display->drm, "failed to write control word\n");
		return -EIO;
	}

	return 0;
}

static unsigned int intel_gmch_vga_set_decode(struct pci_dev *pdev, bool enable_decode)
{
	struct intel_display *display = to_intel_display(pdev);

	intel_gmch_vga_set_state(display, enable_decode);

	if (enable_decode)
		return VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
		       VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
	else
		return VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
}

int intel_vga_register(struct intel_display *display)
{

	struct pci_dev *pdev = to_pci_dev(display->drm->dev);
	int ret;

	/*
	 * If we have > 1 VGA cards, then we need to arbitrate access to the
	 * common VGA resources.
	 *
	 * If we are a secondary display controller (!PCI_DISPLAY_CLASS_VGA),
	 * then we do not take part in VGA arbitration and the
	 * vga_client_register() fails with -ENODEV.
	 */
	ret = vga_client_register(pdev, intel_gmch_vga_set_decode);
	if (ret && ret != -ENODEV)
		return ret;

	return 0;
}

void intel_vga_unregister(struct intel_display *display)
{
	struct pci_dev *pdev = to_pci_dev(display->drm->dev);

	vga_client_unregister(pdev);
}