1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * An example software sink buffer for Intel TH MSU. 4 * 5 * Copyright (C) 2019 Intel Corporation. 6 */ 7 8 #include <linux/intel_th.h> 9 #include <linux/module.h> 10 #include <linux/slab.h> 11 #include <linux/device.h> 12 #include <linux/dma-mapping.h> 13 14 #define MAX_SGTS 16 15 16 struct msu_sink_private { 17 struct device *dev; 18 struct sg_table **sgts; 19 unsigned int nr_sgts; 20 }; 21 22 static void *msu_sink_assign(struct device *dev, int *mode) 23 { 24 struct msu_sink_private *priv; 25 26 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 27 if (!priv) 28 return NULL; 29 30 priv->sgts = kcalloc(MAX_SGTS, sizeof(void *), GFP_KERNEL); 31 if (!priv->sgts) { 32 kfree(priv); 33 return NULL; 34 } 35 36 priv->dev = dev; 37 *mode = MSC_MODE_MULTI; 38 39 return priv; 40 } 41 42 static void msu_sink_unassign(void *data) 43 { 44 struct msu_sink_private *priv = data; 45 46 kfree(priv->sgts); 47 kfree(priv); 48 } 49 50 /* See also: msc.c: __msc_buffer_win_alloc() */ 51 static int msu_sink_alloc_window(void *data, struct sg_table **sgt, size_t size) 52 { 53 struct msu_sink_private *priv = data; 54 unsigned int nents; 55 struct scatterlist *sg_ptr; 56 void *block; 57 int ret, i; 58 59 if (priv->nr_sgts == MAX_SGTS) 60 return -ENOMEM; 61 62 nents = DIV_ROUND_UP(size, PAGE_SIZE); 63 64 ret = sg_alloc_table(*sgt, nents, GFP_KERNEL); 65 if (ret) 66 return -ENOMEM; 67 68 priv->sgts[priv->nr_sgts++] = *sgt; 69 70 for_each_sg((*sgt)->sgl, sg_ptr, nents, i) { 71 block = dma_alloc_coherent(priv->dev->parent->parent, 72 PAGE_SIZE, &sg_dma_address(sg_ptr), 73 GFP_KERNEL); 74 if (!block) 75 return -ENOMEM; 76 77 sg_set_buf(sg_ptr, block, PAGE_SIZE); 78 } 79 80 return nents; 81 } 82 83 /* See also: msc.c: __msc_buffer_win_free() */ 84 static void msu_sink_free_window(void *data, struct sg_table *sgt) 85 { 86 struct msu_sink_private *priv = data; 87 struct scatterlist *sg_ptr; 88 int i; 89 90 for_each_sg(sgt->sgl, sg_ptr, sgt->nents, i) { 91 dma_free_coherent(priv->dev->parent->parent, PAGE_SIZE, 92 sg_virt(sg_ptr), sg_dma_address(sg_ptr)); 93 } 94 95 sg_free_table(sgt); 96 priv->nr_sgts--; 97 } 98 99 static int msu_sink_ready(void *data, struct sg_table *sgt, size_t bytes) 100 { 101 struct msu_sink_private *priv = data; 102 103 intel_th_msc_window_unlock(priv->dev, sgt); 104 105 return 0; 106 } 107 108 static const struct msu_buffer sink_mbuf = { 109 .name = "sink", 110 .assign = msu_sink_assign, 111 .unassign = msu_sink_unassign, 112 .alloc_window = msu_sink_alloc_window, 113 .free_window = msu_sink_free_window, 114 .ready = msu_sink_ready, 115 }; 116 117 module_intel_th_msu_buffer(sink_mbuf); 118 119 MODULE_LICENSE("GPL v2"); 120