1d9b2a2bbSLauri Kasanen // SPDX-License-Identifier: GPL-2.0 2d9b2a2bbSLauri Kasanen /* 3d9b2a2bbSLauri Kasanen * Support for the N64 cart. 4d9b2a2bbSLauri Kasanen * 5d9b2a2bbSLauri Kasanen * Copyright (c) 2021 Lauri Kasanen 6d9b2a2bbSLauri Kasanen */ 7d9b2a2bbSLauri Kasanen 8*f1e19224SChaitanya Kulkarni #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 9d9b2a2bbSLauri Kasanen #include <linux/bitops.h> 10d9b2a2bbSLauri Kasanen #include <linux/blkdev.h> 11d9b2a2bbSLauri Kasanen #include <linux/dma-mapping.h> 12d9b2a2bbSLauri Kasanen #include <linux/init.h> 13d9b2a2bbSLauri Kasanen #include <linux/module.h> 14d9b2a2bbSLauri Kasanen #include <linux/platform_device.h> 15d9b2a2bbSLauri Kasanen 16d9b2a2bbSLauri Kasanen MODULE_AUTHOR("Lauri Kasanen <cand@gmx.com>"); 17d9b2a2bbSLauri Kasanen MODULE_DESCRIPTION("Driver for the N64 cart"); 18d9b2a2bbSLauri Kasanen MODULE_LICENSE("GPL"); 19d9b2a2bbSLauri Kasanen 20d9b2a2bbSLauri Kasanen static unsigned int start, size; 21d9b2a2bbSLauri Kasanen static u32 __iomem *reg_base; 22d9b2a2bbSLauri Kasanen static struct device *dev; 23d9b2a2bbSLauri Kasanen 24d9b2a2bbSLauri Kasanen #define PI_DRAM_REG 0 25d9b2a2bbSLauri Kasanen #define PI_CART_REG 1 26d9b2a2bbSLauri Kasanen #define PI_READ_REG 2 27d9b2a2bbSLauri Kasanen #define PI_WRITE_REG 3 28d9b2a2bbSLauri Kasanen #define PI_STATUS_REG 4 29d9b2a2bbSLauri Kasanen 30d9b2a2bbSLauri Kasanen #define PI_STATUS_DMA_BUSY (1 << 0) 31d9b2a2bbSLauri Kasanen #define PI_STATUS_IO_BUSY (1 << 1) 32d9b2a2bbSLauri Kasanen 33d9b2a2bbSLauri Kasanen #define CART_DOMAIN 0x10000000 34d9b2a2bbSLauri Kasanen #define CART_MAX 0x1FFFFFFF 35d9b2a2bbSLauri Kasanen 36d9b2a2bbSLauri Kasanen #define MIN_ALIGNMENT 8 37d9b2a2bbSLauri Kasanen 38d9b2a2bbSLauri Kasanen static void n64cart_write_reg(const u8 reg, const u32 value) 39d9b2a2bbSLauri Kasanen { 40d9b2a2bbSLauri Kasanen writel(value, reg_base + reg); 41d9b2a2bbSLauri Kasanen } 42d9b2a2bbSLauri Kasanen 43d9b2a2bbSLauri Kasanen static u32 n64cart_read_reg(const u8 reg) 44d9b2a2bbSLauri Kasanen { 45d9b2a2bbSLauri Kasanen return readl(reg_base + reg); 46d9b2a2bbSLauri Kasanen } 47d9b2a2bbSLauri Kasanen 48d9b2a2bbSLauri Kasanen static void n64cart_wait_dma(void) 49d9b2a2bbSLauri Kasanen { 50d9b2a2bbSLauri Kasanen while (n64cart_read_reg(PI_STATUS_REG) & 51d9b2a2bbSLauri Kasanen (PI_STATUS_DMA_BUSY | PI_STATUS_IO_BUSY)) 52d9b2a2bbSLauri Kasanen cpu_relax(); 53d9b2a2bbSLauri Kasanen } 54d9b2a2bbSLauri Kasanen 55d9b2a2bbSLauri Kasanen /* 56d9b2a2bbSLauri Kasanen * Process a single bvec of a bio. 57d9b2a2bbSLauri Kasanen */ 58d9b2a2bbSLauri Kasanen static bool n64cart_do_bvec(struct device *dev, struct bio_vec *bv, u32 pos) 59d9b2a2bbSLauri Kasanen { 60d9b2a2bbSLauri Kasanen dma_addr_t dma_addr; 61d9b2a2bbSLauri Kasanen const u32 bstart = pos + start; 62d9b2a2bbSLauri Kasanen 63d9b2a2bbSLauri Kasanen /* Alignment check */ 64d9b2a2bbSLauri Kasanen WARN_ON_ONCE((bv->bv_offset & (MIN_ALIGNMENT - 1)) || 65d9b2a2bbSLauri Kasanen (bv->bv_len & (MIN_ALIGNMENT - 1))); 66d9b2a2bbSLauri Kasanen 67d9b2a2bbSLauri Kasanen dma_addr = dma_map_bvec(dev, bv, DMA_FROM_DEVICE, 0); 68d9b2a2bbSLauri Kasanen if (dma_mapping_error(dev, dma_addr)) 69d9b2a2bbSLauri Kasanen return false; 70d9b2a2bbSLauri Kasanen 71d9b2a2bbSLauri Kasanen n64cart_wait_dma(); 72d9b2a2bbSLauri Kasanen 73d9b2a2bbSLauri Kasanen n64cart_write_reg(PI_DRAM_REG, dma_addr + bv->bv_offset); 74d9b2a2bbSLauri Kasanen n64cart_write_reg(PI_CART_REG, (bstart | CART_DOMAIN) & CART_MAX); 75d9b2a2bbSLauri Kasanen n64cart_write_reg(PI_WRITE_REG, bv->bv_len - 1); 76d9b2a2bbSLauri Kasanen 77d9b2a2bbSLauri Kasanen n64cart_wait_dma(); 78d9b2a2bbSLauri Kasanen 79d9b2a2bbSLauri Kasanen dma_unmap_page(dev, dma_addr, bv->bv_len, DMA_FROM_DEVICE); 80d9b2a2bbSLauri Kasanen return true; 81d9b2a2bbSLauri Kasanen } 82d9b2a2bbSLauri Kasanen 83d9b2a2bbSLauri Kasanen static blk_qc_t n64cart_submit_bio(struct bio *bio) 84d9b2a2bbSLauri Kasanen { 85d9b2a2bbSLauri Kasanen struct bio_vec bvec; 86d9b2a2bbSLauri Kasanen u32 pos; 87d9b2a2bbSLauri Kasanen struct bvec_iter iter; 88d9b2a2bbSLauri Kasanen 89d9b2a2bbSLauri Kasanen pos = bio->bi_iter.bi_sector << SECTOR_SHIFT; 90d9b2a2bbSLauri Kasanen 91d9b2a2bbSLauri Kasanen bio_for_each_segment(bvec, bio, iter) { 92d9b2a2bbSLauri Kasanen if (!n64cart_do_bvec(dev, &bvec, pos)) 93d9b2a2bbSLauri Kasanen goto io_error; 94d9b2a2bbSLauri Kasanen pos += bvec.bv_len; 95d9b2a2bbSLauri Kasanen } 96d9b2a2bbSLauri Kasanen 97d9b2a2bbSLauri Kasanen bio_endio(bio); 98d9b2a2bbSLauri Kasanen return BLK_QC_T_NONE; 99d9b2a2bbSLauri Kasanen io_error: 100d9b2a2bbSLauri Kasanen bio_io_error(bio); 101d9b2a2bbSLauri Kasanen return BLK_QC_T_NONE; 102d9b2a2bbSLauri Kasanen } 103d9b2a2bbSLauri Kasanen 104d9b2a2bbSLauri Kasanen static const struct block_device_operations n64cart_fops = { 105d9b2a2bbSLauri Kasanen .owner = THIS_MODULE, 106d9b2a2bbSLauri Kasanen .submit_bio = n64cart_submit_bio, 107d9b2a2bbSLauri Kasanen }; 108d9b2a2bbSLauri Kasanen 109d9b2a2bbSLauri Kasanen /* 110d9b2a2bbSLauri Kasanen * The target device is embedded and RAM-constrained. We save RAM 111d9b2a2bbSLauri Kasanen * by initializing in __init code that gets dropped late in boot. 112d9b2a2bbSLauri Kasanen * For the same reason there is no module or unloading support. 113d9b2a2bbSLauri Kasanen */ 114d9b2a2bbSLauri Kasanen static int __init n64cart_probe(struct platform_device *pdev) 115d9b2a2bbSLauri Kasanen { 116d9b2a2bbSLauri Kasanen int err; 117d9b2a2bbSLauri Kasanen struct request_queue *queue; 118d9b2a2bbSLauri Kasanen struct gendisk *disk; 119d9b2a2bbSLauri Kasanen 120d9b2a2bbSLauri Kasanen if (!start || !size) { 121*f1e19224SChaitanya Kulkarni pr_err("start or size not specified\n"); 122d9b2a2bbSLauri Kasanen return -ENODEV; 123d9b2a2bbSLauri Kasanen } 124d9b2a2bbSLauri Kasanen 125d9b2a2bbSLauri Kasanen if (size & 4095) { 126*f1e19224SChaitanya Kulkarni pr_err("size must be a multiple of 4K\n"); 127d9b2a2bbSLauri Kasanen return -ENODEV; 128d9b2a2bbSLauri Kasanen } 129d9b2a2bbSLauri Kasanen 130d9b2a2bbSLauri Kasanen queue = blk_alloc_queue(NUMA_NO_NODE); 131d9b2a2bbSLauri Kasanen if (!queue) { 132d9b2a2bbSLauri Kasanen return -ENOMEM; 133d9b2a2bbSLauri Kasanen } 134d9b2a2bbSLauri Kasanen 135d9b2a2bbSLauri Kasanen reg_base = devm_platform_ioremap_resource(pdev, 0); 136d9b2a2bbSLauri Kasanen if (!reg_base) { 137d9b2a2bbSLauri Kasanen err = -EINVAL; 138d9b2a2bbSLauri Kasanen goto fail_queue; 139d9b2a2bbSLauri Kasanen } 140d9b2a2bbSLauri Kasanen 141d9b2a2bbSLauri Kasanen disk = alloc_disk(0); 142d9b2a2bbSLauri Kasanen if (!disk) { 143d9b2a2bbSLauri Kasanen err = -ENOMEM; 144d9b2a2bbSLauri Kasanen goto fail_queue; 145d9b2a2bbSLauri Kasanen } 146d9b2a2bbSLauri Kasanen 147d9b2a2bbSLauri Kasanen dev = &pdev->dev; 148d9b2a2bbSLauri Kasanen 149d9b2a2bbSLauri Kasanen disk->first_minor = 0; 150d9b2a2bbSLauri Kasanen disk->queue = queue; 151d9b2a2bbSLauri Kasanen disk->flags = GENHD_FL_NO_PART_SCAN | GENHD_FL_EXT_DEVT; 152d9b2a2bbSLauri Kasanen disk->fops = &n64cart_fops; 153d9b2a2bbSLauri Kasanen strcpy(disk->disk_name, "n64cart"); 154d9b2a2bbSLauri Kasanen 155d9b2a2bbSLauri Kasanen set_capacity(disk, size / 512); 156d9b2a2bbSLauri Kasanen set_disk_ro(disk, 1); 157d9b2a2bbSLauri Kasanen 158d9b2a2bbSLauri Kasanen blk_queue_flag_set(QUEUE_FLAG_NONROT, queue); 159d9b2a2bbSLauri Kasanen blk_queue_physical_block_size(queue, 4096); 160d9b2a2bbSLauri Kasanen blk_queue_logical_block_size(queue, 4096); 161d9b2a2bbSLauri Kasanen 162d9b2a2bbSLauri Kasanen add_disk(disk); 163d9b2a2bbSLauri Kasanen 164d9b2a2bbSLauri Kasanen pr_info("n64cart: %u kb disk\n", size / 1024); 165d9b2a2bbSLauri Kasanen 166d9b2a2bbSLauri Kasanen return 0; 167d9b2a2bbSLauri Kasanen fail_queue: 168d9b2a2bbSLauri Kasanen blk_cleanup_queue(queue); 169d9b2a2bbSLauri Kasanen 170d9b2a2bbSLauri Kasanen return err; 171d9b2a2bbSLauri Kasanen } 172d9b2a2bbSLauri Kasanen 173d9b2a2bbSLauri Kasanen static struct platform_driver n64cart_driver = { 174d9b2a2bbSLauri Kasanen .driver = { 175d9b2a2bbSLauri Kasanen .name = "n64cart", 176d9b2a2bbSLauri Kasanen }, 177d9b2a2bbSLauri Kasanen }; 178d9b2a2bbSLauri Kasanen 179d9b2a2bbSLauri Kasanen static int __init n64cart_init(void) 180d9b2a2bbSLauri Kasanen { 181d9b2a2bbSLauri Kasanen return platform_driver_probe(&n64cart_driver, n64cart_probe); 182d9b2a2bbSLauri Kasanen } 183d9b2a2bbSLauri Kasanen 184d9b2a2bbSLauri Kasanen module_param(start, uint, 0); 185d9b2a2bbSLauri Kasanen MODULE_PARM_DESC(start, "Start address of the cart block data"); 186d9b2a2bbSLauri Kasanen 187d9b2a2bbSLauri Kasanen module_param(size, uint, 0); 188d9b2a2bbSLauri Kasanen MODULE_PARM_DESC(size, "Size of the cart block data, in bytes"); 189d9b2a2bbSLauri Kasanen 190d9b2a2bbSLauri Kasanen module_init(n64cart_init); 191