Simple but effective way of chaging HID device descriptorsusing firmware
loading mechanism.
Just place your new descriptor in a location specified by driver
i.e. somewhere in /lib/firmware/hid/
If it is there it will replace HID descriptor from the device.
I do not do any parsing or checking, as it is done by hid driver.
Signed-off-by: Marcin Tolysz <tolysz@xxxxxxxxx>
---
drivers/hid/hid-core.c | 26 +++++++++++++++++++++++++-
1 files changed, 25 insertions(+), 1 deletions(-)
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 80792d3..5d8d656 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -27,6 +27,7 @@
#include <linux/wait.h>
#include <linux/vmalloc.h>
#include <linux/sched.h>
+#include <linux/firmware.h>
#include <linux/hid.h>
#include <linux/hiddev.h>
@@ -640,6 +641,10 @@ int hid_parse_report(struct hid_device *device,
__u8 *start,
struct hid_item item;
__u8 *end;
int ret;
+ const struct firmware *fw;
+ int succ;
+ char *file;
+
static int (*dispatch_type[])(struct hid_parser *parser,
struct hid_item *item) = {
hid_parser_main,
@@ -650,10 +655,27 @@ int hid_parse_report(struct hid_device *device,
__u8 *start,
if (device->driver->report_fixup)
device->driver->report_fixup(device, start, size);
+ /* Now load a hid descriptor from a file firmware
+ ignoring this fixup thing */
+ file=kmalloc(29, GFP_KERNEL);
+
sprintf(file,"hid/%04X:%04X:%04X:%04X.bin",device->bus,device->vendor,device->product,device->version);
+
+ succ = request_firmware(&fw, file, &device->dev);
+
+ if (succ)
+ printk(KERN_INFO "To relace HID descriptor place it in
/lib/firmaware/%s\n", file);
+ else{
+ start = fw->data;
+ size = fw->size;
+ printk(KERN_INFO "HID descriptor relaced with /lib/firmaware/%s\n",
file);
+ }
+ kfree(file);
device->rdesc = kmalloc(size, GFP_KERNEL);
- if (device->rdesc == NULL)
+ if (device->rdesc == NULL){
+ if(!succ)release_firmware(fw);
return -ENOMEM;
+ }
memcpy(device->rdesc, start, size);
device->rsize = size;
@@ -690,6 +712,7 @@ int hid_parse_report(struct hid_device *device, __u8
*start,
dbg_hid("unbalanced delimiter at end of report description\n");
goto err;
}
+ if(!succ)release_firmware(fw);
vfree(parser);
return 0;
}
@@ -697,6 +720,7 @@ int hid_parse_report(struct hid_device *device, __u8
*start,
dbg_hid("item fetching failed at offset %d\n", (int)(end - start));
err:
+ if(!succ)release_firmware(fw);
vfree(parser);
return ret;
}
-- 1.6.5.7
--
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