Orange Pi5 kernel

// SPDX-License-Identifier: GPL-2.0-only
/* flash.c: Allow mmap access to the OBP Flash, for OBP updates.
 *
 * Copyright (C) 1997  Eddie C. Dost  (ecd@skynet.be)
 */
 
#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/fcntl.h>
#include <linux/poll.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <linux/of.h>
#include <linux/of_device.h>
 
#include <linux/uaccess.h>
#include <asm/io.h>
#include <asm/upa.h>
 
static DEFINE_MUTEX(flash_mutex);
static DEFINE_SPINLOCK(flash_lock);
static struct {
<------>unsigned long read_base;	/* Physical read address */
<------>unsigned long write_base;	/* Physical write address */
<------>unsigned long read_size;	/* Size of read area */
<------>unsigned long write_size;	/* Size of write area */
<------>unsigned long busy;		/* In use? */
} flash;
 
static int
flash_mmap(struct file *file, struct vm_area_struct *vma)
{
<------>unsigned long addr;
<------>unsigned long size;
 
<------>spin_lock(&flash_lock);
<------>if (flash.read_base == flash.write_base) {
<------><------>addr = flash.read_base;
<------><------>size = flash.read_size;
<------>} else {
<------><------>if ((vma->vm_flags & VM_READ) &&
<------><------>    (vma->vm_flags & VM_WRITE)) {
<------><------><------>spin_unlock(&flash_lock);
<------><------><------>return -EINVAL;
<------><------>}
<------><------>if (vma->vm_flags & VM_READ) {
<------><------><------>addr = flash.read_base;
<------><------><------>size = flash.read_size;
<------><------>} else if (vma->vm_flags & VM_WRITE) {
<------><------><------>addr = flash.write_base;
<------><------><------>size = flash.write_size;
<------><------>} else {
<------><------><------>spin_unlock(&flash_lock);
<------><------><------>return -ENXIO;
<------><------>}
<------>}
<------>spin_unlock(&flash_lock);
 
<------>if ((vma->vm_pgoff << PAGE_SHIFT) > size)
<------><------>return -ENXIO;
<------>addr = vma->vm_pgoff + (addr >> PAGE_SHIFT);
 
<------>if (vma->vm_end - (vma->vm_start + (vma->vm_pgoff << PAGE_SHIFT)) > size)
<------><------>size = vma->vm_end - (vma->vm_start + (vma->vm_pgoff << PAGE_SHIFT));
 
<------>vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 
<------>if (io_remap_pfn_range(vma, vma->vm_start, addr, size, vma->vm_page_prot))
<------><------>return -EAGAIN;
<------><------>
<------>return 0;
}
 
static long long
flash_llseek(struct file *file, long long offset, int origin)
{
<------>mutex_lock(&flash_mutex);
<------>switch (origin) {
<------><------>case 0:
<------><------><------>file->f_pos = offset;
<------><------><------>break;
<------><------>case 1:
<------><------><------>file->f_pos += offset;
<------><------><------>if (file->f_pos > flash.read_size)
<------><------><------><------>file->f_pos = flash.read_size;
<------><------><------>break;
<------><------>case 2:
<------><------><------>file->f_pos = flash.read_size;
<------><------><------>break;
<------><------>default:
<------><------><------>mutex_unlock(&flash_mutex);
<------><------><------>return -EINVAL;
<------>}
<------>mutex_unlock(&flash_mutex);
<------>return file->f_pos;
}
 
static ssize_t
flash_read(struct file * file, char __user * buf,
<------>   size_t count, loff_t *ppos)
{
<------>loff_t p = *ppos;
<------>int i;
 
<------>if (count > flash.read_size - p)
<------><------>count = flash.read_size - p;
 
<------>for (i = 0; i < count; i++) {
<------><------>u8 data = upa_readb(flash.read_base + p + i);
<------><------>if (put_user(data, buf))
<------><------><------>return -EFAULT;
<------><------>buf++;
<------>}
 
<------>*ppos += count;
<------>return count;
}
 
static int
flash_open(struct inode *inode, struct file *file)
{
<------>mutex_lock(&flash_mutex);
<------>if (test_and_set_bit(0, (void *)&flash.busy) != 0) {
<------><------>mutex_unlock(&flash_mutex);
<------><------>return -EBUSY;
<------>}
 
<------>mutex_unlock(&flash_mutex);
<------>return 0;
}
 
static int
flash_release(struct inode *inode, struct file *file)
{
<------>spin_lock(&flash_lock);
<------>flash.busy = 0;
<------>spin_unlock(&flash_lock);
 
<------>return 0;
}
 
static const struct file_operations flash_fops = {
<------>/* no write to the Flash, use mmap
<------> * and play flash dependent tricks.
<------> */
<------>.owner =	THIS_MODULE,
<------>.llseek =	flash_llseek,
<------>.read =		flash_read,
<------>.mmap =		flash_mmap,
<------>.open =		flash_open,
<------>.release =	flash_release,
};
 
static struct miscdevice flash_dev = { SBUS_FLASH_MINOR, "flash", &flash_fops };
 
static int flash_probe(struct platform_device *op)
{
<------>struct device_node *dp = op->dev.of_node;
<------>struct device_node *parent;
 
<------>parent = dp->parent;
 
<------>if (!of_node_name_eq(parent, "sbus") &&
<------>    !of_node_name_eq(parent, "sbi") &&
<------>    !of_node_name_eq(parent, "ebus"))
<------><------>return -ENODEV;
 
<------>flash.read_base = op->resource[0].start;
<------>flash.read_size = resource_size(&op->resource[0]);
<------>if (op->resource[1].flags) {
<------><------>flash.write_base = op->resource[1].start;
<------><------>flash.write_size = resource_size(&op->resource[1]);
<------>} else {
<------><------>flash.write_base = op->resource[0].start;
<------><------>flash.write_size = resource_size(&op->resource[0]);
<------>}
<------>flash.busy = 0;
 
<------>printk(KERN_INFO "%pOF: OBP Flash, RD %lx[%lx] WR %lx[%lx]\n",
<------>       op->dev.of_node,
<------>       flash.read_base, flash.read_size,
<------>       flash.write_base, flash.write_size);
 
<------>return misc_register(&flash_dev);
}
 
static int flash_remove(struct platform_device *op)
{
<------>misc_deregister(&flash_dev);
 
<------>return 0;
}
 
static const struct of_device_id flash_match[] = {
<------>{
<------><------>.name = "flashprom",
<------>},
<------>{},
};
MODULE_DEVICE_TABLE(of, flash_match);
 
static struct platform_driver flash_driver = {
<------>.driver = {
<------><------>.name = "flash",
<------><------>.of_match_table = flash_match,
<------>},
<------>.probe		= flash_probe,
<------>.remove		= flash_remove,
};
 
module_platform_driver(flash_driver);
 
MODULE_LICENSE("GPL");