axonram.c

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/*
 * (C) Copyright IBM Deutschland Entwicklung GmbH 2006
 *
 * Author: Maxim Shchetynin <[email protected]>
 *
 * Axon DDR2 device driver.
 * It registers one block device per Axon's DDR2 memory bank found on a system.
 * Block devices are called axonram?, their major and minor numbers are
 * available in /proc/devices, /proc/partitions or in /sys/block/axonram?/dev.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/genhd.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/irq.h>
#include <linux/irqreturn.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/of_device.h>
#include <linux/of_platform.h>

#include <asm/page.h>
#include <asm/prom.h>

#define AXON_RAM_MODULE_NAME        "axonram"
#define AXON_RAM_DEVICE_NAME        "axonram"
#define AXON_RAM_MINORS_PER_DISK    16
#define AXON_RAM_BLOCK_SHIFT        PAGE_SHIFT
#define AXON_RAM_BLOCK_SIZE     1 << AXON_RAM_BLOCK_SHIFT
#define AXON_RAM_SECTOR_SHIFT       9
#define AXON_RAM_SECTOR_SIZE        1 << AXON_RAM_SECTOR_SHIFT
#define AXON_RAM_IRQ_FLAGS      IRQF_SHARED | IRQF_TRIGGER_RISING

static int azfs_major, azfs_minor;

struct axon_ram_bank {
    struct platform_device  *device;
    struct gendisk      *disk;
    unsigned int        irq_id;
    unsigned long       ph_addr;
    unsigned long       io_addr;
    unsigned long       size;
    unsigned long       ecc_counter;
};

static ssize_t
axon_ram_sysfs_ecc(struct device *dev, struct device_attribute *attr, char *buf)
{
    struct platform_device *device = to_platform_device(dev);
    struct axon_ram_bank *bank = device->dev.platform_data;

    BUG_ON(!bank);

    return sprintf(buf, "%ld\n", bank->ecc_counter);
}

static DEVICE_ATTR(ecc, S_IRUGO, axon_ram_sysfs_ecc, NULL);

static irqreturn_t
axon_ram_irq_handler(int irq, void *dev)
{
    struct platform_device *device = dev;
    struct axon_ram_bank *bank = device->dev.platform_data;

    BUG_ON(!bank);

    dev_err(&device->dev, "Correctable memory error occurred\n");
    bank->ecc_counter++;
    return IRQ_HANDLED;
}

static void
axon_ram_make_request(struct request_queue *queue, struct bio *bio)
{
    struct axon_ram_bank *bank = bio->bi_bdev->bd_disk->private_data;
    unsigned long phys_mem, phys_end;
    void *user_mem;
    struct bio_vec *vec;
    unsigned int transfered;
    unsigned short idx;

    phys_mem = bank->io_addr + (bio->bi_sector << AXON_RAM_SECTOR_SHIFT);
    phys_end = bank->io_addr + bank->size;
    transfered = 0;
    bio_for_each_segment(vec, bio, idx) {
        if (unlikely(phys_mem + vec->bv_len > phys_end)) {
            bio_io_error(bio);
            return;
        }

        user_mem = page_address(vec->bv_page) + vec->bv_offset;
        if (bio_data_dir(bio) == READ)
            memcpy(user_mem, (void *) phys_mem, vec->bv_len);
        else
            memcpy((void *) phys_mem, user_mem, vec->bv_len);

        phys_mem += vec->bv_len;
        transfered += vec->bv_len;
    }
    bio_endio(bio, 0);
}

static int
axon_ram_direct_access(struct block_device *device, sector_t sector,
               void **kaddr, unsigned long *pfn)
{
    struct axon_ram_bank *bank = device->bd_disk->private_data;
    loff_t offset;

    offset = sector;
    if (device->bd_part != NULL)
        offset += device->bd_part->start_sect;
    offset <<= AXON_RAM_SECTOR_SHIFT;
    if (offset >= bank->size) {
        dev_err(&bank->device->dev, "Access outside of address space\n");
        return -ERANGE;
    }

    *kaddr = (void *)(bank->ph_addr + offset);
    *pfn = virt_to_phys(kaddr) >> PAGE_SHIFT;

    return 0;
}

static const struct block_device_operations axon_ram_devops = {
    .owner      = THIS_MODULE,
    .direct_access  = axon_ram_direct_access
};

static int axon_ram_probe(struct platform_device *device)
{
    static int axon_ram_bank_id = -1;
    struct axon_ram_bank *bank;
    struct resource resource;
    int rc = 0;

    axon_ram_bank_id++;

    dev_info(&device->dev, "Found memory controller on %s\n",
            device->dev.of_node->full_name);

    bank = kzalloc(sizeof(struct axon_ram_bank), GFP_KERNEL);
    if (bank == NULL) {
        dev_err(&device->dev, "Out of memory\n");
        rc = -ENOMEM;
        goto failed;
    }

    device->dev.platform_data = bank;

    bank->device = device;

    if (of_address_to_resource(device->dev.of_node, 0, &resource) != 0) {
        dev_err(&device->dev, "Cannot access device tree\n");
        rc = -EFAULT;
        goto failed;
    }

    bank->size = resource_size(&resource);

    if (bank->size == 0) {
        dev_err(&device->dev, "No DDR2 memory found for %s%d\n",
                AXON_RAM_DEVICE_NAME, axon_ram_bank_id);
        rc = -ENODEV;
        goto failed;
    }

    dev_info(&device->dev, "Register DDR2 memory device %s%d with %luMB\n",
            AXON_RAM_DEVICE_NAME, axon_ram_bank_id, bank->size >> 20);

    bank->ph_addr = resource.start;
    bank->io_addr = (unsigned long) ioremap_prot(
            bank->ph_addr, bank->size, _PAGE_NO_CACHE);
    if (bank->io_addr == 0) {
        dev_err(&device->dev, "ioremap() failed\n");
        rc = -EFAULT;
        goto failed;
    }

    bank->disk = alloc_disk(AXON_RAM_MINORS_PER_DISK);
    if (bank->disk == NULL) {
        dev_err(&device->dev, "Cannot register disk\n");
        rc = -EFAULT;
        goto failed;
    }

    bank->disk->major = azfs_major;
    bank->disk->first_minor = azfs_minor;
    bank->disk->fops = &axon_ram_devops;
    bank->disk->private_data = bank;
    bank->disk->driverfs_dev = &device->dev;

    sprintf(bank->disk->disk_name, "%s%d",
            AXON_RAM_DEVICE_NAME, axon_ram_bank_id);

    bank->disk->queue = blk_alloc_queue(GFP_KERNEL);
    if (bank->disk->queue == NULL) {
        dev_err(&device->dev, "Cannot register disk queue\n");
        rc = -EFAULT;
        goto failed;
    }

    set_capacity(bank->disk, bank->size >> AXON_RAM_SECTOR_SHIFT);
    blk_queue_make_request(bank->disk->queue, axon_ram_make_request);
    blk_queue_logical_block_size(bank->disk->queue, AXON_RAM_SECTOR_SIZE);
    add_disk(bank->disk);

    bank->irq_id = irq_of_parse_and_map(device->dev.of_node, 0);
    if (bank->irq_id == NO_IRQ) {
        dev_err(&device->dev, "Cannot access ECC interrupt ID\n");
        rc = -EFAULT;
        goto failed;
    }

    rc = request_irq(bank->irq_id, axon_ram_irq_handler,
            AXON_RAM_IRQ_FLAGS, bank->disk->disk_name, device);
    if (rc != 0) {
        dev_err(&device->dev, "Cannot register ECC interrupt handler\n");
        bank->irq_id = NO_IRQ;
        rc = -EFAULT;
        goto failed;
    }

    rc = device_create_file(&device->dev, &dev_attr_ecc);
    if (rc != 0) {
        dev_err(&device->dev, "Cannot create sysfs file\n");
        rc = -EFAULT;
        goto failed;
    }

    azfs_minor += bank->disk->minors;

    return 0;

failed:
    if (bank != NULL) {
        if (bank->irq_id != NO_IRQ)
            free_irq(bank->irq_id, device);
        if (bank->disk != NULL) {
            if (bank->disk->major > 0)
                unregister_blkdev(bank->disk->major,
                        bank->disk->disk_name);
            del_gendisk(bank->disk);
        }
        device->dev.platform_data = NULL;
        if (bank->io_addr != 0)
            iounmap((void __iomem *) bank->io_addr);
        kfree(bank);
    }

    return rc;
}

static int
axon_ram_remove(struct platform_device *device)
{
    struct axon_ram_bank *bank = device->dev.platform_data;

    BUG_ON(!bank || !bank->disk);

    device_remove_file(&device->dev, &dev_attr_ecc);
    free_irq(bank->irq_id, device);
    del_gendisk(bank->disk);
    iounmap((void __iomem *) bank->io_addr);
    kfree(bank);

    return 0;
}

static struct of_device_id axon_ram_device_id[] = {
    {
        .type   = "dma-memory"
    },
    {}
};

static struct platform_driver axon_ram_driver = {
    .probe      = axon_ram_probe,
    .remove     = axon_ram_remove,
    .driver = {
        .name = AXON_RAM_MODULE_NAME,
        .owner = THIS_MODULE,
        .of_match_table = axon_ram_device_id,
    },
};

static int __init
axon_ram_init(void)
{
    azfs_major = register_blkdev(azfs_major, AXON_RAM_DEVICE_NAME);
    if (azfs_major < 0) {
        printk(KERN_ERR "%s cannot become block device major number\n",
                AXON_RAM_MODULE_NAME);
        return -EFAULT;
    }
    azfs_minor = 0;

    return platform_driver_register(&axon_ram_driver);
}

static void __exit
axon_ram_exit(void)
{
    platform_driver_unregister(&axon_ram_driver);
    unregister_blkdev(azfs_major, AXON_RAM_DEVICE_NAME);
}

module_init(axon_ram_init);
module_exit(axon_ram_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Maxim Shchetynin <[email protected]>");
MODULE_DESCRIPTION("Axon DDR2 RAM device driver for IBM Cell BE");