intel_vga.c revision 1.5 
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#include <video/vga.h>
11
12#include "i915_drv.h"
13#include "intel_de.h"
14#include "intel_vga.h"
15
16static i915_reg_t intel_vga_cntrl_reg(struct drm_i915_private *i915)
17{
18	if (IS_VALLEYVIEW(i915) || IS_CHERRYVIEW(i915))
19		return VLV_VGACNTRL;
20	else if (DISPLAY_VER(i915) >= 5)
21		return CPU_VGACNTRL;
22	else
23		return VGACNTRL;
24}
25
26/* Disable the VGA plane that we never use */
27void intel_vga_disable(struct drm_i915_private *dev_priv)
28{
29	struct pci_dev *pdev = dev_priv->drm.pdev;
30	i915_reg_t vga_reg = intel_vga_cntrl_reg(dev_priv);
31	u8 sr1;
32
33	if (intel_de_read(dev_priv, vga_reg) & VGA_DISP_DISABLE)
34		return;
35
36	/* WaEnableVGAAccessThroughIOPort:ctg,elk,ilk,snb,ivb,vlv,hsw */
37	vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO);
38#ifdef __linux__
39	outb(0x01, VGA_SEQ_I);
40	sr1 = inb(VGA_SEQ_D);
41	outb(sr1 | VGA_SR01_SCREEN_OFF, VGA_SEQ_D);
42#else
43	outb(VGA_SEQ_I, 0x01);
44	sr1 = inb(VGA_SEQ_D);
45	outb(VGA_SEQ_D, sr1 | VGA_SR01_SCREEN_OFF);
46#endif
47	vga_put(pdev, VGA_RSRC_LEGACY_IO);
48	udelay(300);
49
50	intel_de_write(dev_priv, vga_reg, VGA_DISP_DISABLE);
51	intel_de_posting_read(dev_priv, vga_reg);
52}
53
54void intel_vga_redisable_power_on(struct drm_i915_private *dev_priv)
55{
56	i915_reg_t vga_reg = intel_vga_cntrl_reg(dev_priv);
57
58	if (!(intel_de_read(dev_priv, vga_reg) & VGA_DISP_DISABLE)) {
59		drm_dbg_kms(&dev_priv->drm,
60			    "Something enabled VGA plane, disabling it\n");
61		intel_vga_disable(dev_priv);
62	}
63}
64
65void intel_vga_redisable(struct drm_i915_private *i915)
66{
67	intel_wakeref_t wakeref;
68
69	/*
70	 * This function can be called both from intel_modeset_setup_hw_state or
71	 * at a very early point in our resume sequence, where the power well
72	 * structures are not yet restored. Since this function is at a very
73	 * paranoid "someone might have enabled VGA while we were not looking"
74	 * level, just check if the power well is enabled instead of trying to
75	 * follow the "don't touch the power well if we don't need it" policy
76	 * the rest of the driver uses.
77	 */
78	wakeref = intel_display_power_get_if_enabled(i915, POWER_DOMAIN_VGA);
79	if (!wakeref)
80		return;
81
82	intel_vga_redisable_power_on(i915);
83
84	intel_display_power_put(i915, POWER_DOMAIN_VGA, wakeref);
85}
86
87void intel_vga_reset_io_mem(struct drm_i915_private *i915)
88{
89	struct pci_dev *pdev = i915->drm.pdev;
90
91	/*
92	 * After we re-enable the power well, if we touch VGA register 0x3d5
93	 * we'll get unclaimed register interrupts. This stops after we write
94	 * anything to the VGA MSR register. The vgacon module uses this
95	 * register all the time, so if we unbind our driver and, as a
96	 * consequence, bind vgacon, we'll get stuck in an infinite loop at
97	 * console_unlock(). So make here we touch the VGA MSR register, making
98	 * sure vgacon can keep working normally without triggering interrupts
99	 * and error messages.
100	 */
101	vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO);
102#ifdef __linux__
103	outb(inb(VGA_MIS_R), VGA_MIS_W);
104#else
105	outb(VGA_MIS_W, inb(VGA_MIS_R));
106#endif
107	vga_put(pdev, VGA_RSRC_LEGACY_IO);
108}
109
110static int
111intel_vga_set_state(struct drm_i915_private *i915, bool enable_decode)
112{
113	unsigned int reg = DISPLAY_VER(i915) >= 6 ? SNB_GMCH_CTRL : INTEL_GMCH_CTRL;
114	u16 gmch_ctrl;
115
116	if (pci_read_config_word(i915->bridge_dev, reg, &gmch_ctrl)) {
117		drm_err(&i915->drm, "failed to read control word\n");
118		return -EIO;
119	}
120
121	if (!!(gmch_ctrl & INTEL_GMCH_VGA_DISABLE) == !enable_decode)
122		return 0;
123
124	if (enable_decode)
125		gmch_ctrl &= ~INTEL_GMCH_VGA_DISABLE;
126	else
127		gmch_ctrl |= INTEL_GMCH_VGA_DISABLE;
128
129	if (pci_write_config_word(i915->bridge_dev, reg, gmch_ctrl)) {
130		drm_err(&i915->drm, "failed to write control word\n");
131		return -EIO;
132	}
133
134	return 0;
135}
136
137static unsigned int
138intel_vga_set_decode(struct pci_dev *pdev, bool enable_decode)
139{
140	STUB();
141	return 0;
142#ifdef notyet
143	struct drm_i915_private *i915 = pdev_to_i915(pdev);
144
145	intel_vga_set_state(i915, enable_decode);
146
147	if (enable_decode)
148		return VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
149		       VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
150	else
151		return VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
152#endif
153}
154
155int intel_vga_register(struct drm_i915_private *i915)
156{
157
158	struct pci_dev *pdev = i915->drm.pdev;
159	int ret;
160
161	/*
162	 * If we have > 1 VGA cards, then we need to arbitrate access to the
163	 * common VGA resources.
164	 *
165	 * If we are a secondary display controller (!PCI_DISPLAY_CLASS_VGA),
166	 * then we do not take part in VGA arbitration and the
167	 * vga_client_register() fails with -ENODEV.
168	 */
169	ret = vga_client_register(pdev, intel_vga_set_decode);
170	if (ret && ret != -ENODEV)
171		return ret;
172
173	return 0;
174}
175
176void intel_vga_unregister(struct drm_i915_private *i915)
177{
178	struct pci_dev *pdev = i915->drm.pdev;
179
180	vga_client_unregister(pdev);
181}
182