intel_sbi.c

 1// SPDX-License-Identifier: MIT
 2/*
 3 * Copyright © 2013-2021 Intel Corporation
 4 *
 5 * LPT/WPT IOSF sideband.
 6 */
 7
 8#include <drm/drm_print.h>
 9
10#include "intel_de.h"
11#include "intel_display_core.h"
12#include "intel_sbi.h"
13#include "intel_sbi_regs.h"
14
15/* SBI access */
16static int intel_sbi_rw(struct intel_display *display, u16 reg,
17			enum intel_sbi_destination destination,
18			u32 *val, bool is_read)
19{
20	u32 cmd;
21
22	lockdep_assert_held(&display->sbi.lock);
23
24	if (intel_de_wait_fw_ms(display, SBI_CTL_STAT,
25				SBI_STATUS_MASK, SBI_STATUS_READY, 100, NULL)) {
26		drm_err(display->drm, "timeout waiting for SBI to become ready\n");
27		return -EBUSY;
28	}
29
30	intel_de_write_fw(display, SBI_ADDR, SBI_ADDR_VALUE(reg));
31	intel_de_write_fw(display, SBI_DATA, is_read ? 0 : *val);
32
33	if (destination == SBI_ICLK)
34		cmd = SBI_CTL_DEST_ICLK | SBI_CTL_OP_CRRD;
35	else
36		cmd = SBI_CTL_DEST_MPHY | SBI_CTL_OP_IORD;
37	if (!is_read)
38		cmd |= SBI_CTL_OP_WR;
39	intel_de_write_fw(display, SBI_CTL_STAT, cmd | SBI_STATUS_BUSY);
40
41	if (intel_de_wait_fw_ms(display, SBI_CTL_STAT,
42				SBI_STATUS_MASK, SBI_STATUS_READY, 100, &cmd)) {
43		drm_err(display->drm, "timeout waiting for SBI to complete read\n");
44		return -ETIMEDOUT;
45	}
46
47	if (cmd & SBI_RESPONSE_FAIL) {
48		drm_err(display->drm, "error during SBI read of reg %x\n", reg);
49		return -ENXIO;
50	}
51
52	if (is_read)
53		*val = intel_de_read_fw(display, SBI_DATA);
54
55	return 0;
56}
57
58void intel_sbi_lock(struct intel_display *display)
59{
60	mutex_lock(&display->sbi.lock);
61}
62
63void intel_sbi_unlock(struct intel_display *display)
64{
65	mutex_unlock(&display->sbi.lock);
66}
67
68u32 intel_sbi_read(struct intel_display *display, u16 reg,
69		   enum intel_sbi_destination destination)
70{
71	u32 result = 0;
72
73	intel_sbi_rw(display, reg, destination, &result, true);
74
75	return result;
76}
77
78void intel_sbi_write(struct intel_display *display, u16 reg, u32 value,
79		     enum intel_sbi_destination destination)
80{
81	intel_sbi_rw(display, reg, destination, &value, false);
82}
83
84void intel_sbi_init(struct intel_display *display)
85{
86	mutex_init(&display->sbi.lock);
87}
88
89void intel_sbi_fini(struct intel_display *display)
90{
91	mutex_destroy(&display->sbi.lock);
92}