179 lines
3.9 KiB
C
179 lines
3.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Support for the N64 cart.
|
|
*
|
|
* Copyright (c) 2021 Lauri Kasanen
|
|
*/
|
|
|
|
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
|
|
#include <linux/bitops.h>
|
|
#include <linux/blkdev.h>
|
|
#include <linux/dma-mapping.h>
|
|
#include <linux/init.h>
|
|
#include <linux/module.h>
|
|
#include <linux/platform_device.h>
|
|
|
|
enum {
|
|
PI_DRAM_REG = 0,
|
|
PI_CART_REG,
|
|
PI_READ_REG,
|
|
PI_WRITE_REG,
|
|
PI_STATUS_REG,
|
|
};
|
|
|
|
#define PI_STATUS_DMA_BUSY (1 << 0)
|
|
#define PI_STATUS_IO_BUSY (1 << 1)
|
|
|
|
#define CART_DOMAIN 0x10000000
|
|
#define CART_MAX 0x1FFFFFFF
|
|
|
|
#define MIN_ALIGNMENT 8
|
|
|
|
static u32 __iomem *reg_base;
|
|
|
|
static unsigned int start;
|
|
module_param(start, uint, 0);
|
|
MODULE_PARM_DESC(start, "Start address of the cart block data");
|
|
|
|
static unsigned int size;
|
|
module_param(size, uint, 0);
|
|
MODULE_PARM_DESC(size, "Size of the cart block data, in bytes");
|
|
|
|
static void n64cart_write_reg(const u8 reg, const u32 value)
|
|
{
|
|
writel(value, reg_base + reg);
|
|
}
|
|
|
|
static u32 n64cart_read_reg(const u8 reg)
|
|
{
|
|
return readl(reg_base + reg);
|
|
}
|
|
|
|
static void n64cart_wait_dma(void)
|
|
{
|
|
while (n64cart_read_reg(PI_STATUS_REG) &
|
|
(PI_STATUS_DMA_BUSY | PI_STATUS_IO_BUSY))
|
|
cpu_relax();
|
|
}
|
|
|
|
/*
|
|
* Process a single bvec of a bio.
|
|
*/
|
|
static bool n64cart_do_bvec(struct device *dev, struct bio_vec *bv, u32 pos)
|
|
{
|
|
dma_addr_t dma_addr;
|
|
const u32 bstart = pos + start;
|
|
|
|
/* Alignment check */
|
|
WARN_ON_ONCE((bv->bv_offset & (MIN_ALIGNMENT - 1)) ||
|
|
(bv->bv_len & (MIN_ALIGNMENT - 1)));
|
|
|
|
dma_addr = dma_map_bvec(dev, bv, DMA_FROM_DEVICE, 0);
|
|
if (dma_mapping_error(dev, dma_addr))
|
|
return false;
|
|
|
|
n64cart_wait_dma();
|
|
|
|
n64cart_write_reg(PI_DRAM_REG, dma_addr + bv->bv_offset);
|
|
n64cart_write_reg(PI_CART_REG, (bstart | CART_DOMAIN) & CART_MAX);
|
|
n64cart_write_reg(PI_WRITE_REG, bv->bv_len - 1);
|
|
|
|
n64cart_wait_dma();
|
|
|
|
dma_unmap_page(dev, dma_addr, bv->bv_len, DMA_FROM_DEVICE);
|
|
return true;
|
|
}
|
|
|
|
static blk_qc_t n64cart_submit_bio(struct bio *bio)
|
|
{
|
|
struct bio_vec bvec;
|
|
struct bvec_iter iter;
|
|
struct device *dev = bio->bi_disk->private_data;
|
|
u32 pos = bio->bi_iter.bi_sector << SECTOR_SHIFT;
|
|
|
|
bio_for_each_segment(bvec, bio, iter) {
|
|
if (!n64cart_do_bvec(dev, &bvec, pos))
|
|
goto io_error;
|
|
pos += bvec.bv_len;
|
|
}
|
|
|
|
bio_endio(bio);
|
|
return BLK_QC_T_NONE;
|
|
io_error:
|
|
bio_io_error(bio);
|
|
return BLK_QC_T_NONE;
|
|
}
|
|
|
|
static const struct block_device_operations n64cart_fops = {
|
|
.owner = THIS_MODULE,
|
|
.submit_bio = n64cart_submit_bio,
|
|
};
|
|
|
|
/*
|
|
* The target device is embedded and RAM-constrained. We save RAM
|
|
* by initializing in __init code that gets dropped late in boot.
|
|
* For the same reason there is no module or unloading support.
|
|
*/
|
|
static int __init n64cart_probe(struct platform_device *pdev)
|
|
{
|
|
struct gendisk *disk;
|
|
|
|
if (!start || !size) {
|
|
pr_err("start or size not specified\n");
|
|
return -ENODEV;
|
|
}
|
|
|
|
if (size & 4095) {
|
|
pr_err("size must be a multiple of 4K\n");
|
|
return -ENODEV;
|
|
}
|
|
|
|
reg_base = devm_platform_ioremap_resource(pdev, 0);
|
|
if (!reg_base)
|
|
return -EINVAL;
|
|
|
|
disk = alloc_disk(0);
|
|
if (!disk)
|
|
return -ENOMEM;
|
|
|
|
disk->queue = blk_alloc_queue(NUMA_NO_NODE);
|
|
if (!disk->queue)
|
|
return -ENOMEM;
|
|
|
|
disk->first_minor = 0;
|
|
disk->flags = GENHD_FL_NO_PART_SCAN | GENHD_FL_EXT_DEVT;
|
|
disk->fops = &n64cart_fops;
|
|
disk->private_data = &pdev->dev;
|
|
strcpy(disk->disk_name, "n64cart");
|
|
|
|
set_capacity(disk, size >> SECTOR_SHIFT);
|
|
set_disk_ro(disk, 1);
|
|
|
|
blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue);
|
|
blk_queue_physical_block_size(disk->queue, 4096);
|
|
blk_queue_logical_block_size(disk->queue, 4096);
|
|
|
|
add_disk(disk);
|
|
|
|
pr_info("n64cart: %u kb disk\n", size / 1024);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static struct platform_driver n64cart_driver = {
|
|
.driver = {
|
|
.name = "n64cart",
|
|
},
|
|
};
|
|
|
|
static int __init n64cart_init(void)
|
|
{
|
|
return platform_driver_probe(&n64cart_driver, n64cart_probe);
|
|
}
|
|
|
|
module_init(n64cart_init);
|
|
|
|
MODULE_AUTHOR("Lauri Kasanen <cand@gmx.com>");
|
|
MODULE_DESCRIPTION("Driver for the N64 cart");
|
|
MODULE_LICENSE("GPL");
|