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

   1 // SPDX-License-Identifier: MIT
   2 /*
   3  * Copyright © 2019 Intel Corporation
   4  */
   5
   6 #include <linux/pci.h>
   7 #include <linux/vgaarb.h>
   8
   9 #include <drm/i915_drm.h>
  10
  11 #include "i915_drv.h"
  12 #include "intel_vga.h"
  13
  14 static i915_reg_t intel_vga_cntrl_reg(struct drm_i915_private *i915)
  15 {
  16         if (IS_VALLEYVIEW(i915) || IS_CHERRYVIEW(i915))
  17                 return VLV_VGACNTRL;
  18         else if (INTEL_GEN(i915) >= 5)
  19                 return CPU_VGACNTRL;
  20         else
  21                 return VGACNTRL;
  22 }
  23
  24 /* Disable the VGA plane that we never use */
  25 void intel_vga_disable(struct drm_i915_private *dev_priv)
  26 {
  27         struct pci_dev *pdev = dev_priv->drm.pdev;
  28         i915_reg_t vga_reg = intel_vga_cntrl_reg(dev_priv);
  29         u8 sr1;
  30
  31         /* WaEnableVGAAccessThroughIOPort:ctg,elk,ilk,snb,ivb,vlv,hsw */
  32         vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO);
  33         outb(SR01, VGA_SR_INDEX);
  34         sr1 = inb(VGA_SR_DATA);
  35         outb(sr1 | 1 << 5, VGA_SR_DATA);
  36         vga_put(pdev, VGA_RSRC_LEGACY_IO);
  37         udelay(300);
  38
  39         I915_WRITE(vga_reg, VGA_DISP_DISABLE);
  40         POSTING_READ(vga_reg);
  41 }
  42
  43 void intel_vga_redisable_power_on(struct drm_i915_private *dev_priv)
  44 {
  45         i915_reg_t vga_reg = intel_vga_cntrl_reg(dev_priv);
  46
  47         if (!(I915_READ(vga_reg) & VGA_DISP_DISABLE)) {
  48                 DRM_DEBUG_KMS("Something enabled VGA plane, disabling it\n");
  49                 intel_vga_disable(dev_priv);
  50         }
  51 }
  52
  53 void intel_vga_redisable(struct drm_i915_private *i915)
  54 {
  55         intel_wakeref_t wakeref;
  56
  57         /*
  58          * This function can be called both from intel_modeset_setup_hw_state or
  59          * at a very early point in our resume sequence, where the power well
  60          * structures are not yet restored. Since this function is at a very
  61          * paranoid "someone might have enabled VGA while we were not looking"
  62          * level, just check if the power well is enabled instead of trying to
  63          * follow the "don't touch the power well if we don't need it" policy
  64          * the rest of the driver uses.
  65          */
  66         wakeref = intel_display_power_get_if_enabled(i915, POWER_DOMAIN_VGA);
  67         if (!wakeref)
  68                 return;
  69
  70         intel_vga_redisable_power_on(i915);
  71
  72         intel_display_power_put(i915, POWER_DOMAIN_VGA, wakeref);
  73 }
  74
  75 void intel_vga_reset_io_mem(struct drm_i915_private *i915)
  76 {
  77         struct pci_dev *pdev = i915->drm.pdev;
  78
  79         /*
  80          * After we re-enable the power well, if we touch VGA register 0x3d5
  81          * we'll get unclaimed register interrupts. This stops after we write
  82          * anything to the VGA MSR register. The vgacon module uses this
  83          * register all the time, so if we unbind our driver and, as a
  84          * consequence, bind vgacon, we'll get stuck in an infinite loop at
  85          * console_unlock(). So make here we touch the VGA MSR register, making
  86          * sure vgacon can keep working normally without triggering interrupts
  87          * and error messages.
  88          */
  89         vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO);
  90         outb(inb(VGA_MSR_READ), VGA_MSR_WRITE);
  91         vga_put(pdev, VGA_RSRC_LEGACY_IO);
  92 }
  93
  94 static int
  95 intel_vga_set_state(struct drm_i915_private *i915, bool enable_decode)
  96 {
  97         unsigned int reg = INTEL_GEN(i915) >= 6 ? SNB_GMCH_CTRL : INTEL_GMCH_CTRL;
  98         u16 gmch_ctrl;
  99
 100         if (pci_read_config_word(i915->bridge_dev, reg, &gmch_ctrl)) {
 101                 DRM_ERROR("failed to read control word\n");
 102                 return -EIO;
 103         }
 104
 105         if (!!(gmch_ctrl & INTEL_GMCH_VGA_DISABLE) == !enable_decode)
 106                 return 0;
 107
 108         if (enable_decode)
 109                 gmch_ctrl &= ~INTEL_GMCH_VGA_DISABLE;
 110         else
 111                 gmch_ctrl |= INTEL_GMCH_VGA_DISABLE;
 112
 113         if (pci_write_config_word(i915->bridge_dev, reg, gmch_ctrl)) {
 114                 DRM_ERROR("failed to write control word\n");
 115                 return -EIO;
 116         }
 117
 118         return 0;
 119 }
 120
 121 static unsigned int
 122 intel_vga_set_decode(void *cookie, bool enable_decode)
 123 {
 124         struct drm_i915_private *i915 = cookie;
 125
 126         intel_vga_set_state(i915, enable_decode);
 127
 128         if (enable_decode)
 129                 return VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
 130                        VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
 131         else
 132                 return VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
 133 }
 134
 135 int intel_vga_register(struct drm_i915_private *i915)
 136 {
 137         struct pci_dev *pdev = i915->drm.pdev;
 138         int ret;
 139
 140         /*
 141          * If we have > 1 VGA cards, then we need to arbitrate access to the
 142          * common VGA resources.
 143          *
 144          * If we are a secondary display controller (!PCI_DISPLAY_CLASS_VGA),
 145          * then we do not take part in VGA arbitration and the
 146          * vga_client_register() fails with -ENODEV.
 147          */
 148         ret = vga_client_register(pdev, i915, NULL, intel_vga_set_decode);
 149         if (ret && ret != -ENODEV)
 150                 return ret;
 151
 152         return 0;
 153 }
 154
 155 void intel_vga_unregister(struct drm_i915_private *i915)
 156 {
 157         struct pci_dev *pdev = i915->drm.pdev;
 158
 159         vga_client_register(pdev, NULL, NULL, NULL);
 160 }