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 (INTEL_GEN(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 = dev_priv->drm.pdev;
29 	i915_reg_t vga_reg = intel_vga_cntrl_reg(dev_priv);
30 	u8 sr1;
31 
32 	/* WaEnableVGAAccessThroughIOPort:ctg,elk,ilk,snb,ivb,vlv,hsw */
33 	vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO);
34 	outb(SR01, VGA_SR_INDEX);
35 	sr1 = inb(VGA_SR_DATA);
36 	outb(sr1 | 1 << 5, VGA_SR_DATA);
37 	vga_put(pdev, VGA_RSRC_LEGACY_IO);
38 	udelay(300);
39 
40 	intel_de_write(dev_priv, vga_reg, VGA_DISP_DISABLE);
41 	intel_de_posting_read(dev_priv, vga_reg);
42 }
43 
44 void intel_vga_redisable_power_on(struct drm_i915_private *dev_priv)
45 {
46 	i915_reg_t vga_reg = intel_vga_cntrl_reg(dev_priv);
47 
48 	if (!(intel_de_read(dev_priv, vga_reg) & VGA_DISP_DISABLE)) {
49 		drm_dbg_kms(&dev_priv->drm,
50 			    "Something enabled VGA plane, disabling it\n");
51 		intel_vga_disable(dev_priv);
52 	}
53 }
54 
55 void intel_vga_redisable(struct drm_i915_private *i915)
56 {
57 	intel_wakeref_t wakeref;
58 
59 	/*
60 	 * This function can be called both from intel_modeset_setup_hw_state or
61 	 * at a very early point in our resume sequence, where the power well
62 	 * structures are not yet restored. Since this function is at a very
63 	 * paranoid "someone might have enabled VGA while we were not looking"
64 	 * level, just check if the power well is enabled instead of trying to
65 	 * follow the "don't touch the power well if we don't need it" policy
66 	 * the rest of the driver uses.
67 	 */
68 	wakeref = intel_display_power_get_if_enabled(i915, POWER_DOMAIN_VGA);
69 	if (!wakeref)
70 		return;
71 
72 	intel_vga_redisable_power_on(i915);
73 
74 	intel_display_power_put(i915, POWER_DOMAIN_VGA, wakeref);
75 }
76 
77 void intel_vga_reset_io_mem(struct drm_i915_private *i915)
78 {
79 	struct pci_dev *pdev = i915->drm.pdev;
80 
81 	/*
82 	 * After we re-enable the power well, if we touch VGA register 0x3d5
83 	 * we'll get unclaimed register interrupts. This stops after we write
84 	 * anything to the VGA MSR register. The vgacon module uses this
85 	 * register all the time, so if we unbind our driver and, as a
86 	 * consequence, bind vgacon, we'll get stuck in an infinite loop at
87 	 * console_unlock(). So make here we touch the VGA MSR register, making
88 	 * sure vgacon can keep working normally without triggering interrupts
89 	 * and error messages.
90 	 */
91 	vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO);
92 	outb(inb(VGA_MSR_READ), VGA_MSR_WRITE);
93 	vga_put(pdev, VGA_RSRC_LEGACY_IO);
94 }
95 
96 static int
97 intel_vga_set_state(struct drm_i915_private *i915, bool enable_decode)
98 {
99 	unsigned int reg = INTEL_GEN(i915) >= 6 ? SNB_GMCH_CTRL : INTEL_GMCH_CTRL;
100 	u16 gmch_ctrl;
101 
102 	if (pci_read_config_word(i915->bridge_dev, reg, &gmch_ctrl)) {
103 		drm_err(&i915->drm, "failed to read control word\n");
104 		return -EIO;
105 	}
106 
107 	if (!!(gmch_ctrl & INTEL_GMCH_VGA_DISABLE) == !enable_decode)
108 		return 0;
109 
110 	if (enable_decode)
111 		gmch_ctrl &= ~INTEL_GMCH_VGA_DISABLE;
112 	else
113 		gmch_ctrl |= INTEL_GMCH_VGA_DISABLE;
114 
115 	if (pci_write_config_word(i915->bridge_dev, reg, gmch_ctrl)) {
116 		drm_err(&i915->drm, "failed to write control word\n");
117 		return -EIO;
118 	}
119 
120 	return 0;
121 }
122 
123 static unsigned int
124 intel_vga_set_decode(void *cookie, bool enable_decode)
125 {
126 	struct drm_i915_private *i915 = cookie;
127 
128 	intel_vga_set_state(i915, enable_decode);
129 
130 	if (enable_decode)
131 		return VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
132 		       VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
133 	else
134 		return VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
135 }
136 
137 int intel_vga_register(struct drm_i915_private *i915)
138 {
139 	struct pci_dev *pdev = i915->drm.pdev;
140 	int ret;
141 
142 	/*
143 	 * If we have > 1 VGA cards, then we need to arbitrate access to the
144 	 * common VGA resources.
145 	 *
146 	 * If we are a secondary display controller (!PCI_DISPLAY_CLASS_VGA),
147 	 * then we do not take part in VGA arbitration and the
148 	 * vga_client_register() fails with -ENODEV.
149 	 */
150 	ret = vga_client_register(pdev, i915, NULL, intel_vga_set_decode);
151 	if (ret && ret != -ENODEV)
152 		return ret;
153 
154 	return 0;
155 }
156 
157 void intel_vga_unregister(struct drm_i915_private *i915)
158 {
159 	struct pci_dev *pdev = i915->drm.pdev;
160 
161 	vga_client_register(pdev, NULL, NULL, NULL);
162 }
163