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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2018 Intel Corporation
* VGA Shared Memory driver for Aspeed AST2500
*/
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/of_platform.h>
#define SHAREDMEM_NAME "vgasharedmem"
struct aspeed_vga_sharedmem {
struct miscdevice miscdev;
unsigned int addr;
unsigned int size;
bool mmap_enable;
};
static struct aspeed_vga_sharedmem *file_sharemem(struct file *file)
{
return container_of(file->private_data,
struct aspeed_vga_sharedmem, miscdev);
}
static int vga_open(struct inode *inode, struct file *file)
{
struct aspeed_vga_sharedmem *vga_sharedmem = file_sharemem(file);
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (!vga_sharedmem->mmap_enable)
return -EPERM;
return 0;
}
static int vga_mmap(struct file *file, struct vm_area_struct *vma)
{
struct aspeed_vga_sharedmem *vga_sharedmem = file_sharemem(file);
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
vma->vm_flags = (vma->vm_flags & (~VM_WRITE));
remap_pfn_range(vma, vma->vm_start, vga_sharedmem->addr >> PAGE_SHIFT,
vga_sharedmem->size, vma->vm_page_prot);
return 0;
}
static ssize_t enable_mmap_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct aspeed_vga_sharedmem *vga_sharedmem = dev_get_drvdata(dev);
return sprintf(buf, "%u\n", vga_sharedmem->mmap_enable);
}
static ssize_t enable_mmap_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct aspeed_vga_sharedmem *vga_sharedmem =
dev_get_drvdata(dev);
bool val;
if (kstrtobool(buf, &val))
return -EINVAL;
vga_sharedmem->mmap_enable = val;
return count;
}
static DEVICE_ATTR_RW(enable_mmap);
static struct attribute *sharedmem_attrs[] = {
&dev_attr_enable_mmap.attr,
NULL
};
static const struct attribute_group sharedmem_attr_group = {
.attrs = sharedmem_attrs,
};
static const struct attribute_group *sharedmem_attr_groups[] = {
&sharedmem_attr_group,
NULL
};
static const struct file_operations vga_sharedmem_fops = {
.owner = THIS_MODULE,
.open = vga_open,
.mmap = vga_mmap,
};
static struct miscdevice vga_sharedmem_miscdev = {
.minor = MISC_DYNAMIC_MINOR,
.name = SHAREDMEM_NAME,
.fops = &vga_sharedmem_fops,
.groups = sharedmem_attr_groups,
};
static int vga_sharedmem_probe(struct platform_device *pdev)
{
struct aspeed_vga_sharedmem *vga_sharedmem;
struct device *dev = &pdev->dev;
struct resource *rc;
vga_sharedmem = devm_kzalloc(dev, sizeof(*vga_sharedmem), GFP_KERNEL);
if (!vga_sharedmem)
return -ENOMEM;
dev_set_drvdata(&pdev->dev, vga_sharedmem);
rc = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!rc) {
dev_err(dev, "Couldn't read size device-tree property\n");
return -ENXIO;
}
vga_sharedmem->addr = rc->start;
vga_sharedmem->size = resource_size(rc);
vga_sharedmem->mmap_enable = true;
vga_sharedmem->miscdev = vga_sharedmem_miscdev;
return misc_register(&vga_sharedmem->miscdev);
}
static int vga_sharedmem_remove(struct platform_device *pdev)
{
struct aspeed_vga_sharedmem *vga_sharedmem =
dev_get_drvdata(&pdev->dev);
misc_deregister(&vga_sharedmem->miscdev);
return 0;
}
static const struct of_device_id vga_sharedmem_match[] = {
{ .compatible = "aspeed,ast2500-vga-sharedmem", },
{ }
};
MODULE_DEVICE_TABLE(of, vga_sharedmem_match);
static struct platform_driver vga_sharedmem_driver = {
.driver = {
.name = "VGA-SHAREDMEM",
.of_match_table = vga_sharedmem_match,
},
.probe = vga_sharedmem_probe,
.remove = vga_sharedmem_remove,
};
module_platform_driver(vga_sharedmem_driver);
MODULE_AUTHOR("Yang Cheng <cheng.c.yang@intel.com>");
MODULE_DESCRIPTION("Shared VGA memory");
MODULE_LICENSE("GPL v2");
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