fsi: core: Fix legacy minor numbering

The legacy minor numbering shifts the chip id too much,
resulting in ids that overlap with regular ids. Since there
are only 2 bits for 4 types, only shift the chip id by 2
to fit the legacy ids in their reserved space.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20230612195657.245125-10-eajames@linux.ibm.com
Signed-off-by: Joel Stanley <joel@jms.id.au>

diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
index 161c458..8735edd 100644 (file)
--- a/drivers/fsi/fsi-core.c
+++ b/drivers/fsi/fsi-core.c
@@ -913,8 +913,12 @@ static int __fsi_get_new_minor(struct fsi_slave *slave, enum fsi_dev_type type,
 
        /* Check if we qualify for legacy numbering */
        if (cid >= 0 && cid < 16 && type < 4) {
-               /* Try reserving the legacy number */
-               id = (cid << 4) | type;
+               /*
+                * Try reserving the legacy number, which has 0 - 0x3f reserved
+                * in the ida range. cid goes up to 0xf and type contains two
+                * bits, so construct the id with the below two bit shift.
+                */
+               id = (cid << 2) | type;
                id = ida_simple_get(&fsi_minor_ida, id, id + 1, GFP_KERNEL);
                if (id >= 0) {
                        *out_index = fsi_adjust_index(cid);
@@ -949,7 +953,8 @@ int fsi_get_new_minor(struct fsi_device *fdev, enum fsi_dev_type type,
                int aid = of_alias_get_id(fdev->dev.of_node, fsi_dev_type_names[type]);
 
                if (aid >= 0) {
-                       int id = (aid << 4) | type;
+                       /* Use the same scheme as the legacy numbers. */
+                       int id = (aid << 2) | type;
 
                        id = ida_simple_get(&fsi_minor_ida, id, id + 1, GFP_KERNEL);
                        if (id >= 0) {