No functional changes, just cleanup.
Clarify actual integer size limits in a few comments.
Make one constant explicit to improve readability.
Replace open-coded sign-extension with common routine.
Signed-off-by: Kenneth Albanowski <kenalba@xxxxxxxxxx>
---
drivers/hid/hid-core.c | 19 +++++++------------
include/linux/hid.h | 3 ++-
2 files changed, 9 insertions(+), 13 deletions(-)
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 5b30783e2353d..19b2b0aae0c7e 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -337,7 +337,8 @@ static int hid_add_field(struct hid_parser *parser, unsigned report_type, unsign
}
/*
- * Read data value from item.
+ * Read data value from global items, which are
+ * a maximum of 32 bits in size.
*/
static u32 item_udata(struct hid_item *item)
@@ -709,7 +710,7 @@ static void hid_device_release(struct device *dev)
/*
* Fetch a report description item from the data stream. We support long
- * items, though they are not used yet.
+ * items, though there are not yet any defined uses for them.
*/
static u8 *fetch_item(__u8 *start, __u8 *end, struct hid_item *item)
@@ -745,6 +746,7 @@ static u8 *fetch_item(__u8 *start, __u8 *end, struct hid_item *item)
item->format = HID_ITEM_FORMAT_SHORT;
item->size = b & 3;
+ /* Map size values 0,1,2,3 to actual sizes 0,1,2,4 */
switch (item->size) {
case 0:
return start;
@@ -763,7 +765,7 @@ static u8 *fetch_item(__u8 *start, __u8 *end, struct hid_item *item)
return start;
case 3:
- item->size++;
+ item->size = 4;
if ((end - start) < 4)
return NULL;
item->data.u32 = get_unaligned_le32(start);
@@ -1300,9 +1302,7 @@ int hid_open_report(struct hid_device *device)
EXPORT_SYMBOL_GPL(hid_open_report);
/*
- * Convert a signed n-bit integer to signed 32-bit integer. Common
- * cases are done through the compiler, the screwed things has to be
- * done by hand.
+ * Convert a signed n-bit integer to signed 32-bit integer.
*/
static s32 snto32(__u32 value, unsigned n)
@@ -1310,12 +1310,7 @@ static s32 snto32(__u32 value, unsigned n)
if (!value || !n)
return 0;
- switch (n) {
- case 8: return ((__s8)value);
- case 16: return ((__s16)value);
- case 32: return ((__s32)value);
- }
- return value & (1 << (n - 1)) ? value | (~0U << n) : value;
+ return sign_extend32(value, n - 1);
}
s32 hid_snto32(__u32 value, unsigned n)
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 7a13e9d3441a4..59828a6080e83 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -391,6 +391,7 @@ struct hid_item {
struct hid_global {
unsigned usage_page;
+ /* HID Global fields are constrained by spec to 32-bits */
__s32 logical_minimum;
__s32 logical_maximum;
__s32 physical_minimum;
@@ -457,7 +458,7 @@ struct hid_field {
unsigned maxusage; /* maximum usage index */
unsigned flags; /* main-item flags (i.e. volatile,array,constant) */
unsigned report_offset; /* bit offset in the report */
- unsigned report_size; /* size of this field in the report */
+ unsigned report_size; /* size of this field in the report, in bits */
unsigned report_count; /* number of this field in the report */
unsigned report_type; /* (input,output,feature) */
__s32 *value; /* last known value(s) */
--
2.31.0
