drivers/hwtracing/intel_th/msu-sink.c

   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_DESCRIPTION("example software sink buffer for Intel TH MSU");
 120 MODULE_LICENSE("GPL v2");