1// SPDX-License-Identifier: GPL-2.0-only
 2
 3#include <linux/delay.h>
 4
 5#include <drm/drm_atomic_helper.h>
 6#include <drm/drm_edid.h>
 7#include <drm/drm_managed.h>
 8#include <drm/drm_probe_helper.h>
 9
10#include "mgag200_drv.h"
11
12void mgag200_bmc_stop_scanout(struct mga_device *mdev)
13{
14	u8 tmp;
15	int iter_max;
16
17	/*
18	 * 1 - The first step is to inform the BMC of an upcoming mode
19	 * change. We are putting the misc<0> to output.
20	 */
21
22	WREG8(DAC_INDEX, MGA1064_GEN_IO_CTL);
23	tmp = RREG8(DAC_DATA);
24	tmp |= 0x10;
25	WREG_DAC(MGA1064_GEN_IO_CTL, tmp);
26
27	/* we are putting a 1 on the misc<0> line */
28	WREG8(DAC_INDEX, MGA1064_GEN_IO_DATA);
29	tmp = RREG8(DAC_DATA);
30	tmp |= 0x10;
31	WREG_DAC(MGA1064_GEN_IO_DATA, tmp);
32
33	/*
34	 * 2- Second step to mask any further scan request. This is
35	 * done by asserting the remfreqmsk bit (XSPAREREG<7>)
36	 */
37
38	WREG8(DAC_INDEX, MGA1064_SPAREREG);
39	tmp = RREG8(DAC_DATA);
40	tmp |= 0x80;
41	WREG_DAC(MGA1064_SPAREREG, tmp);
42
43	/*
44	 * 3a- The third step is to verify if there is an active scan.
45	 * We are waiting for a 0 on remhsyncsts <XSPAREREG<0>).
46	 */
47	iter_max = 300;
48	while (!(tmp & 0x1) && iter_max) {
49		WREG8(DAC_INDEX, MGA1064_SPAREREG);
50		tmp = RREG8(DAC_DATA);
51		udelay(1000);
52		iter_max--;
53	}
54
55	/*
56	 * 3b- This step occurs only if the remove is actually
57	 * scanning. We are waiting for the end of the frame which is
58	 * a 1 on remvsyncsts (XSPAREREG<1>)
59	 */
60	if (iter_max) {
61		iter_max = 300;
62		while ((tmp & 0x2) && iter_max) {
63			WREG8(DAC_INDEX, MGA1064_SPAREREG);
64			tmp = RREG8(DAC_DATA);
65			udelay(1000);
66			iter_max--;
67		}
68	}
69}
70
71void mgag200_bmc_start_scanout(struct mga_device *mdev)
72{
73	u8 tmp;
74
75	/* Assert rstlvl2 */
76	WREG8(DAC_INDEX, MGA1064_REMHEADCTL2);
77	tmp = RREG8(DAC_DATA);
78	tmp |= 0x8;
79	WREG8(DAC_DATA, tmp);
80
81	udelay(10);
82
83	/* Deassert rstlvl2 */
84	tmp &= ~0x08;
85	WREG8(DAC_INDEX, MGA1064_REMHEADCTL2);
86	WREG8(DAC_DATA, tmp);
87
88	/* Remove mask of scan request */
89	WREG8(DAC_INDEX, MGA1064_SPAREREG);
90	tmp = RREG8(DAC_DATA);
91	tmp &= ~0x80;
92	WREG8(DAC_DATA, tmp);
93
94	/* Put back a 0 on the misc<0> line */
95	WREG8(DAC_INDEX, MGA1064_GEN_IO_DATA);
96	tmp = RREG8(DAC_DATA);
97	tmp &= ~0x10;
98	WREG_DAC(MGA1064_GEN_IO_DATA, tmp);
99}