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_de.h"
  13 #include "intel_vga.h"
  14
  15 static i915_reg_t intel_vga_cntrl_reg(struct drm_i915_private *i915)
  16 {
  17         if (IS_VALLEYVIEW(i915) || IS_CHERRYVIEW(i915))
  18                 return VLV_VGACNTRL;
  19         else if (DISPLAY_VER(i915) >= 5)
  20                 return CPU_VGACNTRL;
  21         else
  22                 return VGACNTRL;
  23 }
  24
  25 /* Disable the VGA plane that we never use */
  26 void intel_vga_disable(struct drm_i915_private *dev_priv)
  27 {
  28         struct pci_dev *pdev = to_pci_dev(dev_priv->drm.dev);
  29         i915_reg_t vga_reg = intel_vga_cntrl_reg(dev_priv);
  30         u8 sr1;
  31
  32         if (intel_de_read(dev_priv, vga_reg) & VGA_DISP_DISABLE)
  33                 return;
  34
  35         /* WaEnableVGAAccessThroughIOPort:ctg,elk,ilk,snb,ivb,vlv,hsw */
  36         vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO);
  37         outb(SR01, VGA_SR_INDEX);
  38         sr1 = inb(VGA_SR_DATA);
  39         outb(sr1 | 1 << 5, VGA_SR_DATA);
  40         vga_put(pdev, VGA_RSRC_LEGACY_IO);
  41         udelay(300);
  42
  43         intel_de_write(dev_priv, vga_reg, VGA_DISP_DISABLE);
  44         intel_de_posting_read(dev_priv, vga_reg);
  45 }
  46
  47 void intel_vga_redisable_power_on(struct drm_i915_private *dev_priv)
  48 {
  49         i915_reg_t vga_reg = intel_vga_cntrl_reg(dev_priv);
  50
  51         if (!(intel_de_read(dev_priv, vga_reg) & VGA_DISP_DISABLE)) {
  52                 drm_dbg_kms(&dev_priv->drm,
  53                             "Something enabled VGA plane, disabling it\n");
  54                 intel_vga_disable(dev_priv);
  55         }
  56 }
  57
  58 void intel_vga_redisable(struct drm_i915_private *i915)
  59 {
  60         intel_wakeref_t wakeref;
  61
  62         /*
  63          * This function can be called both from intel_modeset_setup_hw_state or
  64          * at a very early point in our resume sequence, where the power well
  65          * structures are not yet restored. Since this function is at a very
  66          * paranoid "someone might have enabled VGA while we were not looking"
  67          * level, just check if the power well is enabled instead of trying to
  68          * follow the "don't touch the power well if we don't need it" policy
  69          * the rest of the driver uses.
  70          */
  71         wakeref = intel_display_power_get_if_enabled(i915, POWER_DOMAIN_VGA);
  72         if (!wakeref)
  73                 return;
  74
  75         intel_vga_redisable_power_on(i915);
  76
  77         intel_display_power_put(i915, POWER_DOMAIN_VGA, wakeref);
  78 }
  79
  80 void intel_vga_reset_io_mem(struct drm_i915_private *i915)
  81 {
  82         struct pci_dev *pdev = to_pci_dev(i915->drm.dev);
  83
  84         /*
  85          * After we re-enable the power well, if we touch VGA register 0x3d5
  86          * we'll get unclaimed register interrupts. This stops after we write
  87          * anything to the VGA MSR register. The vgacon module uses this
  88          * register all the time, so if we unbind our driver and, as a
  89          * consequence, bind vgacon, we'll get stuck in an infinite loop at
  90          * console_unlock(). So make here we touch the VGA MSR register, making
  91          * sure vgacon can keep working normally without triggering interrupts
  92          * and error messages.
  93          */
  94         vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO);
  95         outb(inb(VGA_MSR_READ), VGA_MSR_WRITE);
  96         vga_put(pdev, VGA_RSRC_LEGACY_IO);
  97 }
  98
  99 static int
 100 intel_vga_set_state(struct drm_i915_private *i915, bool enable_decode)
 101 {
 102         unsigned int reg = DISPLAY_VER(i915) >= 6 ? SNB_GMCH_CTRL : INTEL_GMCH_CTRL;
 103         u16 gmch_ctrl;
 104
 105         if (pci_read_config_word(i915->bridge_dev, reg, &gmch_ctrl)) {
 106                 drm_err(&i915->drm, "failed to read control word\n");
 107                 return -EIO;
 108         }
 109
 110         if (!!(gmch_ctrl & INTEL_GMCH_VGA_DISABLE) == !enable_decode)
 111                 return 0;
 112
 113         if (enable_decode)
 114                 gmch_ctrl &= ~INTEL_GMCH_VGA_DISABLE;
 115         else
 116                 gmch_ctrl |= INTEL_GMCH_VGA_DISABLE;
 117
 118         if (pci_write_config_word(i915->bridge_dev, reg, gmch_ctrl)) {
 119                 drm_err(&i915->drm, "failed to write control word\n");
 120                 return -EIO;
 121         }
 122
 123         return 0;
 124 }
 125
 126 static unsigned int
 127 intel_vga_set_decode(struct pci_dev *pdev, bool enable_decode)
 128 {
 129         struct drm_i915_private *i915 = pdev_to_i915(pdev);
 130
 131         intel_vga_set_state(i915, enable_decode);
 132
 133         if (enable_decode)
 134                 return VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
 135                        VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
 136         else
 137                 return VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
 138 }
 139
 140 int intel_vga_register(struct drm_i915_private *i915)
 141 {
 142
 143         struct pci_dev *pdev = to_pci_dev(i915->drm.dev);
 144         int ret;
 145
 146         /*
 147          * If we have > 1 VGA cards, then we need to arbitrate access to the
 148          * common VGA resources.
 149          *
 150          * If we are a secondary display controller (!PCI_DISPLAY_CLASS_VGA),
 151          * then we do not take part in VGA arbitration and the
 152          * vga_client_register() fails with -ENODEV.
 153          */
 154         ret = vga_client_register(pdev, intel_vga_set_decode);
 155         if (ret && ret != -ENODEV)
 156                 return ret;
 157
 158         return 0;
 159 }
 160
 161 void intel_vga_unregister(struct drm_i915_private *i915)
 162 {
 163         struct pci_dev *pdev = to_pci_dev(i915->drm.dev);
 164
 165         vga_client_unregister(pdev);
 166 }