xref: /openbmc/linux/drivers/gpu/drm/i915/intel_sbi.c (revision ce2fce25)
1 // SPDX-License-Identifier: MIT
2 /*
3  * Copyright © 2013-2021 Intel Corporation
4  *
5  * LPT/WPT IOSF sideband.
6  */
7 
8 #include "i915_drv.h"
9 #include "intel_sbi.h"
10 #include "i915_reg.h"
11 
12 /* SBI access */
intel_sbi_rw(struct drm_i915_private * i915,u16 reg,enum intel_sbi_destination destination,u32 * val,bool is_read)13 static int intel_sbi_rw(struct drm_i915_private *i915, u16 reg,
14 			enum intel_sbi_destination destination,
15 			u32 *val, bool is_read)
16 {
17 	struct intel_uncore *uncore = &i915->uncore;
18 	u32 cmd;
19 
20 	lockdep_assert_held(&i915->sb_lock);
21 
22 	if (intel_wait_for_register_fw(uncore,
23 				       SBI_CTL_STAT, SBI_BUSY, 0,
24 				       100)) {
25 		drm_err(&i915->drm,
26 			"timeout waiting for SBI to become ready\n");
27 		return -EBUSY;
28 	}
29 
30 	intel_uncore_write_fw(uncore, SBI_ADDR, (u32)reg << 16);
31 	intel_uncore_write_fw(uncore, 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 |= BIT(8);
39 	intel_uncore_write_fw(uncore, SBI_CTL_STAT, cmd | SBI_BUSY);
40 
41 	if (__intel_wait_for_register_fw(uncore,
42 					 SBI_CTL_STAT, SBI_BUSY, 0,
43 					 100, 100, &cmd)) {
44 		drm_err(&i915->drm,
45 			"timeout waiting for SBI to complete read\n");
46 		return -ETIMEDOUT;
47 	}
48 
49 	if (cmd & SBI_RESPONSE_FAIL) {
50 		drm_err(&i915->drm, "error during SBI read of reg %x\n", reg);
51 		return -ENXIO;
52 	}
53 
54 	if (is_read)
55 		*val = intel_uncore_read_fw(uncore, SBI_DATA);
56 
57 	return 0;
58 }
59 
intel_sbi_read(struct drm_i915_private * i915,u16 reg,enum intel_sbi_destination destination)60 u32 intel_sbi_read(struct drm_i915_private *i915, u16 reg,
61 		   enum intel_sbi_destination destination)
62 {
63 	u32 result = 0;
64 
65 	intel_sbi_rw(i915, reg, destination, &result, true);
66 
67 	return result;
68 }
69 
intel_sbi_write(struct drm_i915_private * i915,u16 reg,u32 value,enum intel_sbi_destination destination)70 void intel_sbi_write(struct drm_i915_private *i915, u16 reg, u32 value,
71 		     enum intel_sbi_destination destination)
72 {
73 	intel_sbi_rw(i915, reg, destination, &value, false);
74 }
75