intel_vga.c revision 1.1 
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
15static 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 */
26void 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
44void 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
55void 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
77void 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
96static int
97intel_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
123static unsigned int
124intel_vga_set_decode(void *cookie, bool enable_decode)
125{
126	STUB();
127	return 0;
128#ifdef notyet
129	struct drm_i915_private *i915 = cookie;
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#endif
139}
140
141int intel_vga_register(struct drm_i915_private *i915)
142{
143	struct pci_dev *pdev = i915->drm.pdev;
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, i915, NULL, intel_vga_set_decode);
155	if (ret && ret != -ENODEV)
156		return ret;
157
158	return 0;
159}
160
161void intel_vga_unregister(struct drm_i915_private *i915)
162{
163	struct pci_dev *pdev = i915->drm.pdev;
164
165	vga_client_register(pdev, NULL, NULL, NULL);
166}
167