121 lines · c
1// SPDX-License-Identifier: GPL-2.02/*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 1615 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 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() */84static 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 99static 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 108static 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 117module_intel_th_msu_buffer(sink_mbuf);118 119MODULE_DESCRIPTION("example software sink buffer for Intel TH MSU");120MODULE_LICENSE("GPL v2");121