[PATCH v3] axon_ram: add dax_operations support

From: Dan Williams
Date: Wed Apr 19 2017 - 18:38:10 EST


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@xxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
Changes since v2:
* fix return code in the alloc_dax() failure case (Gerald)

arch/powerpc/platforms/Kconfig | 1 +
arch/powerpc/sysdev/axonram.c | 48 +++++++++++++++++++++++++++++++++++-----
2 files changed, 43 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/platforms/Kconfig b/arch/powerpc/platforms/Kconfig
index 7e3a2ebba29b..33244e3d9375 100644
--- a/arch/powerpc/platforms/Kconfig
+++ b/arch/powerpc/platforms/Kconfig
@@ -284,6 +284,7 @@ config CPM2
config AXON_RAM
tristate "Axon DDR2 memory device driver"
depends on PPC_IBM_CELL_BLADE && BLOCK
+ select DAX
default m
help
It registers one block device per Axon's DDR2 memory bank found
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 @@ static int axon_ram_probe(struct platform_device *device)
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);