1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (c) 2021, NVIDIA Corporation.
  4 */
  5
  6#include <linux/device.h>
  7#include <linux/kref.h>
  8#include <linux/of.h>
  9#include <linux/of_device.h>
 10#include <linux/pid.h>
 11#include <linux/slab.h>
 12
 13#include "context.h"
 14#include "dev.h"
 15
 16static void host1x_memory_context_release(struct device *dev)
 17{
 18	/* context device is freed in host1x_memory_context_list_free() */
 19}
 20
 21int host1x_memory_context_list_init(struct host1x *host1x)
 22{
 23	struct host1x_memory_context_list *cdl = &host1x->context_list;
 24	struct device_node *node = host1x->dev->of_node;
 25	struct host1x_memory_context *ctx;
 26	unsigned int i;
 27	int err;
 28
 29	cdl->devs = NULL;
 30	cdl->len = 0;
 31	mutex_init(&cdl->lock);
 32
 33	err = of_property_count_u32_elems(node, "iommu-map");
 34	if (err < 0)
 35		return 0;
 36
 37	cdl->len = err / 4;
 38	cdl->devs = kcalloc(cdl->len, sizeof(*cdl->devs), GFP_KERNEL);
 39	if (!cdl->devs)
 40		return -ENOMEM;
 41
 42	for (i = 0; i < cdl->len; i++) {
 43		ctx = &cdl->devs[i];
 44
 45		ctx->host = host1x;
 46
 47		device_initialize(&ctx->dev);
 48
 49		/*
 50		 * Due to an issue with T194 NVENC, only 38 bits can be used.
 51		 * Anyway, 256GiB of IOVA ought to be enough for anyone.
 52		 */
 53		ctx->dma_mask = DMA_BIT_MASK(38);
 54		ctx->dev.dma_mask = &ctx->dma_mask;
 55		ctx->dev.coherent_dma_mask = ctx->dma_mask;
 56		dev_set_name(&ctx->dev, "host1x-ctx.%d", i);
 57		ctx->dev.bus = &host1x_context_device_bus_type;
 58		ctx->dev.parent = host1x->dev;
 59		ctx->dev.release = host1x_memory_context_release;
 60
 61		ctx->dev.dma_parms = &ctx->dma_parms;
 62		dma_set_max_seg_size(&ctx->dev, UINT_MAX);
 63
 64		err = device_add(&ctx->dev);
 65		if (err) {
 66			dev_err(host1x->dev, "could not add context device %d: %d\n", i, err);
 67			put_device(&ctx->dev);
 68			goto unreg_devices;
 69		}
 70
 71		err = of_dma_configure_id(&ctx->dev, node, true, &i);
 72		if (err) {
 73			dev_err(host1x->dev, "IOMMU configuration failed for context device %d: %d\n",
 74				i, err);
 75			device_unregister(&ctx->dev);
 76			goto unreg_devices;
 77		}
 78
 79		if (!tegra_dev_iommu_get_stream_id(&ctx->dev, &ctx->stream_id) ||
 80		    !device_iommu_mapped(&ctx->dev)) {
 81			dev_err(host1x->dev, "Context device %d has no IOMMU!\n", i);
 82			device_unregister(&ctx->dev);
 83
 84			/*
 85			 * This means that if IOMMU is disabled but context devices
 86			 * are defined in the device tree, Host1x will fail to probe.
 87			 * That's probably OK in this time and age.
 88			 */
 89			err = -EINVAL;
 90
 91			goto unreg_devices;
 92		}
 93	}
 94
 95	return 0;
 96
 97unreg_devices:
 98	while (i--)
 99		device_unregister(&cdl->devs[i].dev);
100
101	kfree(cdl->devs);
102	cdl->devs = NULL;
103	cdl->len = 0;
104
105	return err;
106}
107
108void host1x_memory_context_list_free(struct host1x_memory_context_list *cdl)
109{
110	unsigned int i;
111
112	for (i = 0; i < cdl->len; i++)
113		device_unregister(&cdl->devs[i].dev);
114
115	kfree(cdl->devs);
116	cdl->len = 0;
117}
118
119struct host1x_memory_context *host1x_memory_context_alloc(struct host1x *host1x,
120							  struct device *dev,
121							  struct pid *pid)
122{
123	struct host1x_memory_context_list *cdl = &host1x->context_list;
124	struct host1x_memory_context *free = NULL;
125	int i;
126
127	if (!cdl->len)
128		return ERR_PTR(-EOPNOTSUPP);
129
130	mutex_lock(&cdl->lock);
131
132	for (i = 0; i < cdl->len; i++) {
133		struct host1x_memory_context *cd = &cdl->devs[i];
134
135		if (cd->dev.iommu->iommu_dev != dev->iommu->iommu_dev)
136			continue;
137
138		if (cd->owner == pid) {
139			refcount_inc(&cd->ref);
140			mutex_unlock(&cdl->lock);
141			return cd;
142		} else if (!cd->owner && !free) {
143			free = cd;
144		}
145	}
146
147	if (!free) {
148		mutex_unlock(&cdl->lock);
149		return ERR_PTR(-EBUSY);
150	}
151
152	refcount_set(&free->ref, 1);
153	free->owner = get_pid(pid);
154
155	mutex_unlock(&cdl->lock);
156
157	return free;
158}
159EXPORT_SYMBOL_GPL(host1x_memory_context_alloc);
160
161void host1x_memory_context_get(struct host1x_memory_context *cd)
162{
163	refcount_inc(&cd->ref);
164}
165EXPORT_SYMBOL_GPL(host1x_memory_context_get);
166
167void host1x_memory_context_put(struct host1x_memory_context *cd)
168{
169	struct host1x_memory_context_list *cdl = &cd->host->context_list;
170
171	if (refcount_dec_and_mutex_lock(&cd->ref, &cdl->lock)) {
172		put_pid(cd->owner);
173		cd->owner = NULL;
174		mutex_unlock(&cdl->lock);
175	}
176}
177EXPORT_SYMBOL_GPL(host1x_memory_context_put);