On 2023/08/18 7:12, Michael Schmitz wrote:
Some users of pata_falcon on Q40 have IDE disks in default
IDE little endian byte order, whereas legacy disks use
host-native big-endian byte order as on the Atari Falcon.
Add module parameter 'data_swab' to allow connecting drives
with non-native data byte order. Drives selected by the
data_swap bit mask will have their user data byte-swapped to
host byte order, i.e. 'pata_falcon.data_swab=2' will byte-swap
all user data on drive B, leaving data on drive A in native
byte order. On Q40, drives on a second IDE interface may be
added to the bit mask as bits 2 and 3.
Default setting is no byte swapping, i.e. compatibility with
the native Falcon or Q40 operating system disk format.
Cc: William R Sowerbutts <will@xxxxxxxxxxxxxx>
Cc: Finn Thain <fthain@xxxxxxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Signed-off-by: Michael Schmitz <schmitzmic@xxxxxxxxx>
---
Changes since RFC v4:
Geert Uytterhoeven:
- don't shift static module parameter for drive 3/4 bitmask
- simplify bit mask calculation to always use pdev->id
Finn Thain:
- correct bit numbers for drive 3/4
Changes since RFC v3:
- split off this byte swap handling into separate patch
- add hint regarding third and fourth drive on Q40
Finn Thain:
- rename module parameter to 'data_swab' to better reflect its use
William Sowerbutts:
- correct IDE drive number used in data swap conditional
---
drivers/ata/pata_falcon.c | 26 +++++++++++++++++++++++++-
1 file changed, 25 insertions(+), 1 deletion(-)
diff --git a/drivers/ata/pata_falcon.c b/drivers/ata/pata_falcon.c
index 346259e3bbc8..90488f565d6f 100644
--- a/drivers/ata/pata_falcon.c
+++ b/drivers/ata/pata_falcon.c
@@ -33,6 +33,16 @@
#define DRV_NAME "pata_falcon"
#define DRV_VERSION "0.1.0"
+static int pata_falcon_swap_mask;
+
+module_param_named(data_swab, pata_falcon_swap_mask, int, 0444);
+MODULE_PARM_DESC(data_swab, "Data byte swap enable/disable bitmap (0x1==drive1, 0x2==drive2, 0x4==drive3, 0x8==drive4, default==0)");
+
+struct pata_falcon_priv {
+ unsigned int swap_mask;
+ bool swap_data;
+};
+
static const struct scsi_host_template pata_falcon_sht = {
ATA_PIO_SHT(DRV_NAME),
};
@@ -44,13 +54,15 @@ static unsigned int pata_falcon_data_xfer(struct ata_queued_cmd *qc,
struct ata_device *dev = qc->dev;
struct ata_port *ap = dev->link->ap;
void __iomem *data_addr = ap->ioaddr.data_addr;
+ struct pata_falcon_priv *priv = ap->private_data;
unsigned int words = buflen >> 1;
struct scsi_cmnd *cmd = qc->scsicmd;
+ int dev_id = dev->devno;
bool swap = 1;
if (dev->class == ATA_DEV_ATA && cmd &&
!blk_rq_is_passthrough(scsi_cmd_to_rq(cmd)))
- swap = 0;
+ swap = priv->swap_data && (priv->swap_mask & BIT(dev_id));
/* Transfer multiple of 2 bytes */
if (rw == READ) {
@@ -123,6 +135,7 @@ static int __init pata_falcon_init_one(struct platform_device *pdev)
struct resource *base_res, *ctl_res, *irq_res;
struct ata_host *host;
struct ata_port *ap;
+ struct pata_falcon_priv *priv;
void __iomem *base, *ctl_base;
int irq = 0, io_offset = 1, reg_scale = 4;
@@ -165,6 +178,13 @@ static int __init pata_falcon_init_one(struct platform_device *pdev)
ap->pio_mask = ATA_PIO4;
ap->flags |= ATA_FLAG_SLAVE_POSS | ATA_FLAG_NO_IORDY;
+ priv = devm_kzalloc(&pdev->dev,
+ sizeof(struct pata_falcon_priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ ap->private_data = priv;
+
/* N.B. this assumes data_addr will be used for word-sized I/O only */
ap->ioaddr.data_addr = (void __iomem *)base_mem_res->start;
@@ -199,6 +219,10 @@ static int __init pata_falcon_init_one(struct platform_device *pdev)
ap->ioaddr.altstatus_addr = ctl_base + io_offset;
ap->ioaddr.ctl_addr = ctl_base + io_offset;
+ priv->swap_mask = pata_falcon_swap_mask >> (2 * pdev->id);
I do not understand the shift here. It seems that it will lead to
priv->swap_mask always being 0...
+ if (priv->swap_mask)
+ priv->swap_data = 1;
I do not understand why priv->swap_data is needed, given that it is set to 1 if
priv->swap_mask != 0, the above:
swap = priv->swap_data && (priv->swap_mask & BIT(dev_id));
should be equivalent to the simpler:
swap = priv->swap_mask & BIT(dev_id);
No ? Am I missing something ?
+
irq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
if (irq_res && irq_res->start > 0) {
irq = irq_res->start;
--
Damien Le Moal
Western Digital Research
