[v9] block: Add n64 cart driver

Message ID	20210122110043.f36cd22df1233754753518c1@gmx.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-block-owner@kernel.org> Date: Fri, 22 Jan 2021 11:00:43 +0200 From: Lauri Kasanen <cand@gmx.com> To: linux-mips@vger.kernel.org Cc: tsbogend@alpha.franken.de, axboe@kernel.dk, linux-block@vger.kernel.org, Keith Busch <kbusch@kernel.org>, Christoph Hellwig <hch@infradead.org> Subject: [PATCH v9] block: Add n64 cart driver Message-Id: <20210122110043.f36cd22df1233754753518c1@gmx.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Precedence: bulk
Series	[v9] block: Add n64 cart driver \| expand [v9] block: Add n64 cart driver

diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig index ecceaaa..924d768 100644 --- a/drivers/block/Kconfig +++ b/drivers/block/Kconfig @@ -72,6 +72,12 @@ config AMIGA_Z2RAM To compile this driver as a module, choose M here: the module will be called z2ram. +config N64CART + bool "N64 cart support" + depends on MACH_NINTENDO64 + help + Support for the N64 cart. + config CDROM tristate select BLK_SCSI_REQUEST diff --git a/drivers/block/Makefile b/drivers/block/Makefile index e1f6311..b9642cf 100644 --- a/drivers/block/Makefile +++ b/drivers/block/Makefile @@ -17,6 +17,7 @@ obj-$(CONFIG_PS3_DISK) += ps3disk.o obj-$(CONFIG_PS3_VRAM) += ps3vram.o obj-$(CONFIG_ATARI_FLOPPY) += ataflop.o obj-$(CONFIG_AMIGA_Z2RAM) += z2ram.o +obj-$(CONFIG_N64CART) += n64cart.o obj-$(CONFIG_BLK_DEV_RAM) += brd.o obj-$(CONFIG_BLK_DEV_LOOP) += loop.o obj-$(CONFIG_XILINX_SYSACE) += xsysace.o diff --git a/drivers/block/n64cart.c b/drivers/block/n64cart.c new file mode 100644 index 0000000..01dd008 --- /dev/null +++ b/drivers/block/n64cart.c @@ -0,0 +1,211 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Support for the N64 cart. + * + * Copyright (c) 2021 Lauri Kasanen + */ + +#include <linux/bitops.h> +#include <linux/blk-mq.h> +#include <linux/dma-mapping.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/platform_device.h> + +MODULE_AUTHOR("Lauri Kasanen <cand@gmx.com>"); +MODULE_DESCRIPTION("Driver for the N64 cart"); +MODULE_LICENSE("GPL"); + +#define BUFSIZE SZ_64K + +static unsigned int start, size; +static struct request_queue *queue; +static struct blk_mq_tag_set tag_set; +static struct gendisk *disk; + +static void *buf; +static dma_addr_t dma_addr; + +static u32 __iomem *reg_base; + +#define PI_DRAM_REG 0 +#define PI_CART_REG 1 +#define PI_READ_REG 2 +#define PI_WRITE_REG 3 +#define PI_STATUS_REG 4 + +#define PI_STATUS_DMA_BUSY (1 << 0) +#define PI_STATUS_IO_BUSY (1 << 1) + +#define CART_DOMAIN 0x10000000 +#define CART_MAX 0x1FFFFFFF + +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(); +} + +static blk_status_t n64cart_get_seg(struct request *req) +{ + u32 bstart = blk_rq_pos(req) * 512; + u32 len = blk_rq_cur_bytes(req); + void *dst = bio_data(req->bio); + + if (bstart + len > size) + return BLK_STS_IOERR; + + bstart += start; + + while (len) { + const u32 curlen = min_t(u32, len, BUFSIZE); + + dma_sync_single_for_device(disk_to_dev(disk), dma_addr, + BUFSIZE, DMA_FROM_DEVICE); + + n64cart_wait_dma(); + + n64cart_write_reg(PI_DRAM_REG, dma_addr); + n64cart_write_reg(PI_CART_REG, + (bstart | CART_DOMAIN) & CART_MAX); + n64cart_write_reg(PI_WRITE_REG, curlen - 1); + + n64cart_wait_dma(); + + dma_sync_single_for_cpu(disk_to_dev(disk), dma_addr, + BUFSIZE, DMA_FROM_DEVICE); + + memcpy(dst, buf, curlen); + + len -= curlen; + dst += curlen; + bstart += curlen; + } + + return BLK_STS_OK; +} + +static blk_status_t n64cart_queue_rq(struct blk_mq_hw_ctx *hctx, + const struct blk_mq_queue_data *bd) +{ + struct request *req = bd->rq; + blk_status_t err; + + blk_mq_start_request(req); + + do { + err = n64cart_get_seg(req); + } while (blk_update_request(req, err, blk_rq_cur_bytes(req))); + + __blk_mq_end_request(req, BLK_STS_OK); + return BLK_STS_OK; +} + +static const struct blk_mq_ops n64cart_mq_ops = { + .queue_rq = n64cart_queue_rq, +}; + +static const struct block_device_operations n64cart_fops = { + .owner = THIS_MODULE, +}; + +/* + * 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) +{ + int err; + + if (!start || !size) { + pr_err("n64cart: start and size not specified\n"); + return -ENODEV; + } + + if (size & 4095) { + pr_err("n64cart: size must be a multiple of 4K\n"); + return -ENODEV; + } + + queue = blk_mq_init_sq_queue(&tag_set, &n64cart_mq_ops, 1, + BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_BLOCKING); + if (IS_ERR(queue)) { + return PTR_ERR(queue); + } + + buf = dma_alloc_noncoherent(&pdev->dev, BUFSIZE, &dma_addr, + DMA_FROM_DEVICE, GFP_KERNEL); + if (!buf) { + err = -ENOMEM; + goto fail_queue; + } + + reg_base = devm_platform_ioremap_resource(pdev, 0); + if (!reg_base) { + err = -EINVAL; + goto fail_dma; + } + + disk = alloc_disk(0); + if (!disk) { + err = -ENOMEM; + goto fail_dma; + } + + disk->first_minor = 0; + disk->queue = queue; + disk->flags = GENHD_FL_NO_PART_SCAN | GENHD_FL_EXT_DEVT; + disk->fops = &n64cart_fops; + strcpy(disk->disk_name, "n64cart"); + + set_capacity(disk, size / 512); + set_disk_ro(disk, 1); + + blk_queue_flag_set(QUEUE_FLAG_NONROT, queue); + blk_queue_physical_block_size(queue, 4096); + blk_queue_logical_block_size(queue, 4096); + + add_disk(disk); + + pr_info("n64cart: %u kb disk\n", size / 1024); + + return 0; +fail_dma: + dma_free_noncoherent(&pdev->dev, BUFSIZE, buf, dma_addr, + DMA_FROM_DEVICE); +fail_queue: + blk_cleanup_queue(queue); + + return err; +} + +static struct platform_driver n64cart_driver = { + .driver = { + .name = "n64cart", + }, +}; + +static int __init n64cart_init(void) +{ + return platform_driver_probe(&n64cart_driver, n64cart_probe); +} + +module_param(start, uint, 0); +MODULE_PARM_DESC(start, "Start address of the cart block data"); + +module_param(size, uint, 0); +MODULE_PARM_DESC(size, "Size of the cart block data, in bytes"); + +module_init(n64cart_init);

[v9] block: Add n64 cart driver

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