LXR linux/drivers/hwtracing/intel

   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
  16struct msu_sink_private {
  17        struct device   *dev;
  18        struct sg_table **sgts;
  19        unsigned int    nr_sgts;
  20};
  21
  22static 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
  42static 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() */
  51static 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                sg_set_buf(sg_ptr, block, PAGE_SIZE);
  75        }
  76
  77        return nents;
  78}
  79
  80/* See also: msc.c: __msc_buffer_win_free() */
  81static void msu_sink_free_window(void *data, struct sg_table *sgt)
  82{
  83        struct msu_sink_private *priv = data;
  84        struct scatterlist *sg_ptr;
  85        int i;
  86
  87        for_each_sg(sgt->sgl, sg_ptr, sgt->nents, i) {
  88                dma_free_coherent(priv->dev->parent->parent, PAGE_SIZE,
  89                                  sg_virt(sg_ptr), sg_dma_address(sg_ptr));
  90        }
  91
  92        sg_free_table(sgt);
  93        priv->nr_sgts--;
  94}
  95
  96static int msu_sink_ready(void *data, struct sg_table *sgt, size_t bytes)
  97{
  98        struct msu_sink_private *priv = data;
  99
 100        intel_th_msc_window_unlock(priv->dev, sgt);
 101
 102        return 0;
 103}
 104
 105static const struct msu_buffer sink_mbuf = {
 106        .name           = "sink",
 107        .assign         = msu_sink_assign,
 108        .unassign       = msu_sink_unassign,
 109        .alloc_window   = msu_sink_alloc_window,
 110        .free_window    = msu_sink_free_window,
 111        .ready          = msu_sink_ready,
 112};
 113
 114module_intel_th_msu_buffer(sink_mbuf);
 115
 116MODULE_LICENSE("GPL v2");
 117