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axonram.c

/*
 * (C) Copyright IBM Deutschland Entwicklung GmbH 2006
 *
 * Author: Maxim Shchetynin <maxim@de.ibm.com>
 *
 * 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/buffer_head.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;

00062 struct axon_ram_bank {
      struct of_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 of_device *device = to_of_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);

/**
 * axon_ram_irq_handler - interrupt handler for Axon RAM ECC
 * @irq: interrupt ID
 * @dev: pointer to of_device
 */
static irqreturn_t
axon_ram_irq_handler(int irq, void *dev)
{
      struct of_device *device = dev;
      struct axon_ram_bank *bank = device->dev.platform_data;

      BUG_ON(!bank);

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

/**
 * axon_ram_make_request - make_request() method for block device
 * @queue, @bio: see blk_queue_make_request()
 */
static int
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;
      int rc = 0;

      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);
                  rc = -ERANGE;
                  break;
            }

            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);

      return rc;
}

/**
 * axon_ram_direct_access - direct_access() method for block device
 * @device, @sector, @data: see block_device_operations method
 */
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 struct block_device_operations axon_ram_devops = {
      .owner            = THIS_MODULE,
      .direct_access    = axon_ram_direct_access
};

/**
 * axon_ram_probe - probe() method for platform driver
 * @device, @device_id: see of_platform_driver method
 */
static int
axon_ram_probe(struct of_device *device, const struct of_device_id *device_id)
{
      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->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->node, 0, &resource) != 0) {
            dev_err(&device->dev, "Cannot access device tree\n");
            rc = -EFAULT;
            goto failed;
      }

      bank->size = resource.end - resource.start + 1;

      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_flags(
                  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_hardsect_size(bank->disk->queue, AXON_RAM_SECTOR_SIZE);
      add_disk(bank->disk);

      bank->irq_id = irq_of_parse_and_map(device->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;
}

/**
 * axon_ram_remove - remove() method for platform driver
 * @device: see of_platform_driver method
 */
static int
axon_ram_remove(struct of_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 of_platform_driver axon_ram_driver = {
      .match_table      = axon_ram_device_id,
      .probe            = axon_ram_probe,
      .remove           = axon_ram_remove,
      .driver           = {
            .owner      = THIS_MODULE,
            .name = AXON_RAM_MODULE_NAME,
      },
};

/**
 * axon_ram_init
 */
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 of_register_platform_driver(&axon_ram_driver);
}

/**
 * axon_ram_exit
 */
static void __exit
axon_ram_exit(void)
{
      of_unregister_platform_driver(&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 <maxim@de.ibm.com>");
MODULE_DESCRIPTION("Axon DDR2 RAM device driver for IBM Cell BE");

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