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Message-ID: <20081003120305.GA2229@yoda.jdub.homelinux.org>
Date: Fri, 3 Oct 2008 08:03:05 -0400
From: Josh Boyer <jwboyer@...ux.vnet.ibm.com>
To: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: linux-kernel@...r.kernel.org, linuxppc-dev@...abs.org
Subject: Re: [RFC/PATCH] Block device for the ISS simulator
On Fri, Oct 03, 2008 at 10:08:42AM +1000, Benjamin Herrenschmidt wrote:
>+static void iss_blk_setup(struct iss_blk *ib)
>+{
>+ unsigned long flags;
>+ u32 stat;
>+
>+ pr_debug("iss_blk_setup %d\n", ib->devno);
>+
>+ spin_lock_irqsave(&iss_blk_reglock, flags);
>+ out_8(iss_blk_regs->data, 0);
>+ out_be32(&iss_blk_regs->devno, ib->devno);
>+ out_8(&iss_blk_regs->cmd, ISS_BD_CMD_OPEN);
>+ stat = in_be32(&iss_blk_regs->stat);
Should probably use the ioread/iowrite functions instead of raw out/in.
Same comment throughout.
<snip>
>+static void iss_blk_do_request(struct request_queue * q)
>+{
>+ struct iss_blk *ib = q->queuedata;
>+ struct request *req;
>+ int rc = 0;
>+
>+ pr_debug("iss_do_request dev %d\n", ib->devno);
>+
>+ while ((req = elv_next_request(q)) != NULL) {
>+ pr_debug(" -> req @ %p, changed: %d\n", req, ib->changed);
>+ if (ib->changed) {
>+ end_request(req, 0); /* failure */
>+ continue;
>+ }
>+ switch (rq_data_dir(req)) {
>+ case READ:
>+ rc = __iss_blk_read(ib, req->buffer, req->sector,
>+ req->current_nr_sectors);
>+ break;
>+ case WRITE:
>+ rc = __iss_blk_write(ib, req->buffer, req->sector,
>+ req->current_nr_sectors);
>+ };
>+
>+ pr_debug(" -> ending request, rc = %d\n", rc);
>+ if (rc)
>+ end_request(req, 0); /* failure */
>+ else
>+ end_request(req, 1); /* success */
Could possibly just do:
end_request(req, (!rc));
<snip>
>+static int __init iss_blk_init(void)
>+{
>+ struct device_node *np;
>+ int i;
>+
>+ pr_debug("iss_regs offsets:\n");
>+ pr_debug(" cmd : 0x%x\n", offsetof(struct iss_blk_regs, cmd));
>+ pr_debug(" stat : 0x%x\n", offsetof(struct iss_blk_regs, stat));
>+ pr_debug(" sector : 0x%x\n", offsetof(struct iss_blk_regs, sector));
>+ pr_debug(" count : 0x%x\n", offsetof(struct iss_blk_regs, count));
>+ pr_debug(" devno : 0x%x\n", offsetof(struct iss_blk_regs, devno));
>+ pr_debug(" size : 0x%x\n", offsetof(struct iss_blk_regs, size));
>+ pr_debug(" data : 0x%x\n", offsetof(struct iss_blk_regs, data));
>+
>+ np = of_find_node_by_path("/iss-block");
>+ if (np == NULL)
>+ return -ENODEV;
>+ iss_blk_regs = of_iomap(np, 0);
of_find_node_by_path increments the refcount for that node. Need to
do an of_node_put when you are done.
>+ if (iss_blk_regs == NULL) {
>+ pr_err("issblk: Failed to map registers\n");
>+ return -ENOMEM;
>+ }
>+
>+ if (register_blkdev(MAJOR_NR, "iss_blk"))
>+ return -EIO;
>+
>+ spin_lock_init(&iss_blk_qlock);
>+ spin_lock_init(&iss_blk_reglock);
>+
>+ printk(KERN_INFO "ISS Block driver initializing for %d minors\n",
>+ NUM_ISS_BLK_MINOR);
>+
>+ for (i = 0; i < NUM_ISS_BLK_MINOR; i++) {
>+ struct gendisk *disk = alloc_disk(1);
>+ struct request_queue *q;
>+ struct iss_blk *ib = &iss_blks[i];
>+
>+ if (!disk) {
>+ pr_err("issblk%d: Failed to allocate disk\n", i);
>+ break;
>+ }
>+
>+ q = blk_init_queue(iss_blk_do_request, &iss_blk_qlock);
>+ if (q == NULL) {
>+ pr_err("issblk%d: Failed to init queue\n", i);
>+ put_disk(disk);
>+ break;
>+ }
>+ q->queuedata = ib;
>+
>+ ib->disk = disk;
>+ ib->devno = i;
>+ ib->present = 0;
>+ ib->changed = 0;
>+ ib->capacity = 0;
>+ ib->sectsize = 512;
>+
>+ disk->major = MAJOR_NR;
>+ disk->first_minor = i;
>+ disk->fops = &iss_blk_fops;
>+ disk->private_data = &iss_blks[i];
>+ disk->flags = GENHD_FL_REMOVABLE;
>+ disk->queue = q;
>+ sprintf(disk->disk_name, "issblk%d", i);
>+
>+ iss_blk_setup(ib);
>+
>+ add_disk(disk);
>+ }
>+
>+ return 0;
>+}
>+
>+static void __exit iss_blk_exit(void)
>+{
>+ int i;
>+
>+ unregister_blkdev(MAJOR_NR, "iss_blk");
>+
>+ for (i = 0; i < NUM_ISS_BLK_MINOR; i++) {
>+ struct iss_blk *ib = &iss_blks[i];
>+
>+ if (ib->present) {
>+ out_be32(&iss_blk_regs->devno, ib->devno);
>+ out_8(&iss_blk_regs->cmd, ISS_BD_CMD_CLOSE);
>+ }
>+ }
Shouldn't you unmap iss_blk_regs at this point?
<snip>
>Index: linux-work/drivers/block/Kconfig
>===================================================================
>--- linux-work.orig/drivers/block/Kconfig 2008-07-17 14:43:58.000000000 +1000
>+++ linux-work/drivers/block/Kconfig 2008-09-23 11:12:03.000000000 +1000
>@@ -357,6 +357,10 @@ config BLK_DEV_XIP
> will prevent RAM block device backing store memory from being
> allocated from highmem (only a problem for highmem systems).
>
>+config BLK_DEV_ISS
>+ bool "Support ISS Simulator Block Device"
>+ default n
>+
Should probably have:
depends on PPC
josh
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