axon_ram: add dax_operations support

Setup a dax_device to have the same lifetime as the axon_ram block
device and add a ->direct_access() method that is equivalent to
axon_ram_direct_access(). Once fs/dax.c has been converted to use
dax_operations the old axon_ram_direct_access() will be removed.

Reported-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 42 insertions, 6 deletions

diff --git a/arch/powerpc/sysdev/axonram.c b/arch/powerpc/sysdev/axonram.c
index f523ac883150..171ba86a3494 100644
--- a/arch/powerpc/sysdev/axonram.c
+++ b/arch/powerpc/sysdev/axonram.c
@@ -25,6 +25,7 @@
 
 #include <linux/bio.h>
 #include <linux/blkdev.h>
+#include <linux/dax.h>
 #include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/fs.h>
@@ -62,6 +63,7 @@ static int azfs_major, azfs_minor;
 struct axon_ram_bank {
         struct platform_device  *device;
         struct gendisk          *disk;
+        struct dax_device       *dax_dev;
         unsigned int            irq_id;
         unsigned long           ph_addr;
         unsigned long           io_addr;
@@ -137,25 +139,47 @@ axon_ram_make_request(struct request_queue *queue, struct bio *bio)
         return BLK_QC_T_NONE;
 }
 
+static long
+__axon_ram_direct_access(struct axon_ram_bank *bank, pgoff_t pgoff, long nr_pages,
+                       void **kaddr, pfn_t *pfn)
+{
+        resource_size_t offset = pgoff * PAGE_SIZE;
+
+        *kaddr = (void *) bank->io_addr + offset;
+        *pfn = phys_to_pfn_t(bank->ph_addr + offset, PFN_DEV);
+        return (bank->size - offset) / PAGE_SIZE;
+}
+
 /**
  * axon_ram_direct_access - direct_access() method for block device
  * @device, @sector, @data: see block_device_operations method
  */
 static long
-axon_ram_direct_access(struct block_device *device, sector_t sector,
+axon_ram_blk_direct_access(struct block_device *device, sector_t sector,
                        void **kaddr, pfn_t *pfn, long size)
 {
         struct axon_ram_bank *bank = device->bd_disk->private_data;
-        loff_t offset = (loff_t)sector << AXON_RAM_SECTOR_SHIFT;
 
-        *kaddr = (void *) bank->io_addr + offset;
-        *pfn = phys_to_pfn_t(bank->ph_addr + offset, PFN_DEV);
-        return bank->size - offset;
+        return __axon_ram_direct_access(bank, (sector * 512) / PAGE_SIZE,
+                        size / PAGE_SIZE, kaddr, pfn) * PAGE_SIZE;
 }
 
 static const struct block_device_operations axon_ram_devops = {
         .owner          = THIS_MODULE,
-        .direct_access  = axon_ram_direct_access
+        .direct_access  = axon_ram_blk_direct_access
+};
+
+static long
+axon_ram_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages,
+                       void **kaddr, pfn_t *pfn)
+{
+        struct axon_ram_bank *bank = dax_get_private(dax_dev);
+
+        return __axon_ram_direct_access(bank, pgoff, nr_pages, kaddr, pfn);
+}
+
+static const struct dax_operations axon_ram_dax_ops = {
+        .direct_access = axon_ram_dax_direct_access,
 };
 
 /**
@@ -219,6 +243,7 @@ static int axon_ram_probe(struct platform_device *device)
                 goto failed;
         }
 
+
         bank->disk->major = azfs_major;
         bank->disk->first_minor = azfs_minor;
         bank->disk->fops = &axon_ram_devops;
@@ -227,6 +252,13 @@ static int axon_ram_probe(struct platform_device *device)
         sprintf(bank->disk->disk_name, "%s%d",
                         AXON_RAM_DEVICE_NAME, axon_ram_bank_id);
 
+        bank->dax_dev = alloc_dax(bank, bank->disk->disk_name,
+                        &axon_ram_dax_ops);
+        if (!bank->dax_dev) {
+                rc = -ENOMEM;
+                goto failed;
+        }
+
         bank->disk->queue = blk_alloc_queue(GFP_KERNEL);
         if (bank->disk->queue == NULL) {
                 dev_err(&device->dev, "Cannot register disk queue\n");
@@ -278,6 +310,8 @@ failed:
                                 del_gendisk(bank->disk);
                         put_disk(bank->disk);
                 }
+                kill_dax(bank->dax_dev);
+                put_dax(bank->dax_dev);
                 device->dev.platform_data = NULL;
                 if (bank->io_addr != 0)
                         iounmap((void __iomem *) bank->io_addr);
@@ -300,6 +334,8 @@ axon_ram_remove(struct platform_device *device)
 
         device_remove_file(&device->dev, &dev_attr_ecc);
         free_irq(bank->irq_id, device);
+        kill_dax(bank->dax_dev);
+        put_dax(bank->dax_dev);
         del_gendisk(bank->disk);
         put_disk(bank->disk);
         iounmap((void __iomem *) bank->io_addr);