1 // SPDX-License-Identifier: GPL-2.0 OR MIT 2 /* 3 * Copyright 2026 Advanced Micro Devices, Inc. 4 5 * Permission is hereby granted, free of charge, to any person obtaining a 6 * copy of this software and associated documentation files (the "Software"), 7 * to deal in the Software without restriction, including without limitation 8 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 9 * and/or sell copies of the Software, and to permit persons to whom the 10 * Software is furnished to do so, subject to the following conditions: 11 * 12 * The above copyright notice and this permission notice shall be included in 13 * all copies or substantial portions of the Software. 14 * 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 18 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR 19 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 20 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 21 * OTHER DEALINGS IN THE SOFTWARE. 22 */ 23 #include <linux/spinlock.h> 24 25 #include "amdgpu.h" 26 #include "amdgpu_wb.h" 27 28 /* 29 * amdgpu_wb_*() 30 * Writeback is the method by which the GPU updates special pages in memory 31 * with the status of certain GPU events (fences, ring pointers,etc.). 32 */ 33 34 /** 35 * amdgpu_wb_fini - Disable Writeback and free memory 36 * 37 * @adev: amdgpu_device pointer 38 * 39 * Disables Writeback and frees the Writeback memory (all asics). 40 * Used at driver shutdown. 41 */ 42 void amdgpu_wb_fini(struct amdgpu_device *adev) 43 { 44 if (adev->wb.wb_obj) { 45 amdgpu_bo_free_kernel(&adev->wb.wb_obj, 46 &adev->wb.gpu_addr, 47 (void **)&adev->wb.wb); 48 adev->wb.wb_obj = NULL; 49 } 50 } 51 52 /** 53 * amdgpu_wb_init - Init Writeback driver info and allocate memory 54 * 55 * @adev: amdgpu_device pointer 56 * 57 * Initializes writeback and allocates writeback memory (all asics). 58 * Used at driver startup. 59 * Returns 0 on success or an -error on failure. 60 */ 61 int amdgpu_wb_init(struct amdgpu_device *adev) 62 { 63 int r; 64 65 if (adev->wb.wb_obj == NULL) { 66 /* AMDGPU_MAX_WB * sizeof(uint32_t) * 8 = AMDGPU_MAX_WB 256bit slots */ 67 r = amdgpu_bo_create_kernel(adev, AMDGPU_MAX_WB * sizeof(uint32_t) * 8, 68 PAGE_SIZE, AMDGPU_GEM_DOMAIN_GTT, 69 &adev->wb.wb_obj, &adev->wb.gpu_addr, 70 (void **)&adev->wb.wb); 71 if (r) { 72 dev_warn(adev->dev, "(%d) create WB bo failed\n", r); 73 return r; 74 } 75 76 adev->wb.num_wb = AMDGPU_MAX_WB; 77 memset(&adev->wb.used, 0, sizeof(adev->wb.used)); 78 79 /* clear wb memory */ 80 memset((char *)adev->wb.wb, 0, AMDGPU_MAX_WB * sizeof(uint32_t) * 8); 81 } 82 83 return 0; 84 } 85 86 /** 87 * amdgpu_wb_get - Allocate a wb entry 88 * 89 * @adev: amdgpu_device pointer 90 * @wb: wb index 91 * 92 * Allocate a wb slot for use by the driver (all asics). 93 * Returns 0 on success or -EINVAL on failure. 94 */ 95 int amdgpu_wb_get(struct amdgpu_device *adev, u32 *wb) 96 { 97 unsigned long flags, offset; 98 99 spin_lock_irqsave(&adev->wb.lock, flags); 100 offset = find_first_zero_bit(adev->wb.used, adev->wb.num_wb); 101 if (offset < adev->wb.num_wb) { 102 __set_bit(offset, adev->wb.used); 103 spin_unlock_irqrestore(&adev->wb.lock, flags); 104 *wb = offset << 3; /* convert to dw offset */ 105 return 0; 106 } else { 107 spin_unlock_irqrestore(&adev->wb.lock, flags); 108 return -EINVAL; 109 } 110 } 111 112 /** 113 * amdgpu_wb_free - Free a wb entry 114 * 115 * @adev: amdgpu_device pointer 116 * @wb: wb index 117 * 118 * Free a wb slot allocated for use by the driver (all asics) 119 */ 120 void amdgpu_wb_free(struct amdgpu_device *adev, u32 wb) 121 { 122 unsigned long flags; 123 124 wb >>= 3; 125 spin_lock_irqsave(&adev->wb.lock, flags); 126 if (wb < adev->wb.num_wb) 127 __clear_bit(wb, adev->wb.used); 128 spin_unlock_irqrestore(&adev->wb.lock, flags); 129 } 130