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linux-next/drivers/hid/hid-huion.c
Nikolai Kondrashov 6498d02306 HID: huion: Use allocated buffer for DMA 
Allocate a buffer with kmalloc for receiving the parameters string
descriptor with usb_control_msg, instead of using a buffer on the stack,
as the latter is unsafe. Use an enum for indices into the buffer to
ensure the buffer size if sufficient.

This fixes the static checker error "doing dma on the stack (buf)".

Signed-off-by: Nikolai Kondrashov <spbnick@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2014-08-12 12:44:59 +02:00

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/*
* HID driver for Huion devices not fully compliant with HID standard
*
* Copyright (c) 2013 Martin Rusko
* Copyright (c) 2014 Nikolai Kondrashov
*/
/*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*/
#include <linux/device.h>
#include <linux/hid.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <asm/unaligned.h>
#include "usbhid/usbhid.h"
#include "hid-ids.h"
/* Report descriptor template placeholder head */
#define HUION_PH_HEAD 0xFE, 0xED, 0x1D
/* Report descriptor template placeholder IDs */
enum huion_ph_id {
HUION_PH_ID_X_LM,
HUION_PH_ID_X_PM,
HUION_PH_ID_Y_LM,
HUION_PH_ID_Y_PM,
HUION_PH_ID_PRESSURE_LM,
HUION_PH_ID_NUM
};
/* Report descriptor template placeholder */
#define HUION_PH(_ID) HUION_PH_HEAD, HUION_PH_ID_##_ID
/* Fixed report descriptor template */
static const __u8 huion_tablet_rdesc_template[] = {
0x05, 0x0D, /* Usage Page (Digitizer), */
0x09, 0x02, /* Usage (Pen), */
0xA1, 0x01, /* Collection (Application), */
0x85, 0x07, /* Report ID (7), */
0x09, 0x20, /* Usage (Stylus), */
0xA0, /* Collection (Physical), */
0x14, /* Logical Minimum (0), */
0x25, 0x01, /* Logical Maximum (1), */
0x75, 0x01, /* Report Size (1), */
0x09, 0x42, /* Usage (Tip Switch), */
0x09, 0x44, /* Usage (Barrel Switch), */
0x09, 0x46, /* Usage (Tablet Pick), */
0x95, 0x03, /* Report Count (3), */
0x81, 0x02, /* Input (Variable), */
0x95, 0x03, /* Report Count (3), */
0x81, 0x03, /* Input (Constant, Variable), */
0x09, 0x32, /* Usage (In Range), */
0x95, 0x01, /* Report Count (1), */
0x81, 0x02, /* Input (Variable), */
0x95, 0x01, /* Report Count (1), */
0x81, 0x03, /* Input (Constant, Variable), */
0x75, 0x10, /* Report Size (16), */
0x95, 0x01, /* Report Count (1), */
0xA4, /* Push, */
0x05, 0x01, /* Usage Page (Desktop), */
0x65, 0x13, /* Unit (Inch), */
0x55, 0xFD, /* Unit Exponent (-3), */
0x34, /* Physical Minimum (0), */
0x09, 0x30, /* Usage (X), */
0x27, HUION_PH(X_LM), /* Logical Maximum (PLACEHOLDER), */
0x47, HUION_PH(X_PM), /* Physical Maximum (PLACEHOLDER), */
0x81, 0x02, /* Input (Variable), */
0x09, 0x31, /* Usage (Y), */
0x27, HUION_PH(Y_LM), /* Logical Maximum (PLACEHOLDER), */
0x47, HUION_PH(Y_PM), /* Physical Maximum (PLACEHOLDER), */
0x81, 0x02, /* Input (Variable), */
0xB4, /* Pop, */
0x09, 0x30, /* Usage (Tip Pressure), */
0x27,
HUION_PH(PRESSURE_LM), /* Logical Maximum (PLACEHOLDER), */
0x81, 0x02, /* Input (Variable), */
0xC0, /* End Collection, */
0xC0 /* End Collection */
};
/* Parameter indices */
enum huion_prm {
HUION_PRM_X_LM = 1,
HUION_PRM_Y_LM = 2,
HUION_PRM_PRESSURE_LM = 4,
HUION_PRM_RESOLUTION = 5,
HUION_PRM_NUM
};
/* Driver data */
struct huion_drvdata {
__u8 *rdesc;
unsigned int rsize;
};
static __u8 *huion_report_fixup(struct hid_device *hdev, __u8 *rdesc,
unsigned int *rsize)
{
struct huion_drvdata *drvdata = hid_get_drvdata(hdev);
switch (hdev->product) {
case USB_DEVICE_ID_HUION_TABLET:
if (drvdata->rdesc != NULL) {
rdesc = drvdata->rdesc;
*rsize = drvdata->rsize;
}
break;
}
return rdesc;
}
/**
* Enable fully-functional tablet mode and determine device parameters.
*
* @hdev: HID device
*/
static int huion_tablet_enable(struct hid_device *hdev)
{
int rc;
struct usb_device *usb_dev = hid_to_usb_dev(hdev);
struct huion_drvdata *drvdata = hid_get_drvdata(hdev);
__le16 *buf = NULL;
size_t len;
s32 params[HUION_PH_ID_NUM];
s32 resolution;
__u8 *p;
s32 v;
/*
* Read string descriptor containing tablet parameters. The specific
* string descriptor and data were discovered by sniffing the Windows
* driver traffic.
* NOTE: This enables fully-functional tablet mode.
*/
len = HUION_PRM_NUM * sizeof(*buf);
buf = kmalloc(len, GFP_KERNEL);
if (buf == NULL) {
hid_err(hdev, "failed to allocate parameter buffer\n");
rc = -ENOMEM;
goto cleanup;
}
rc = usb_control_msg(usb_dev, usb_rcvctrlpipe(usb_dev, 0),
USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,
(USB_DT_STRING << 8) + 0x64,
0x0409, buf, len,
USB_CTRL_GET_TIMEOUT);
if (rc == -EPIPE) {
hid_err(hdev, "device parameters not found\n");
rc = -ENODEV;
goto cleanup;
} else if (rc < 0) {
hid_err(hdev, "failed to get device parameters: %d\n", rc);
rc = -ENODEV;
goto cleanup;
} else if (rc != len) {
hid_err(hdev, "invalid device parameters\n");
rc = -ENODEV;
goto cleanup;
}
/* Extract device parameters */
params[HUION_PH_ID_X_LM] = le16_to_cpu(buf[HUION_PRM_X_LM]);
params[HUION_PH_ID_Y_LM] = le16_to_cpu(buf[HUION_PRM_Y_LM]);
params[HUION_PH_ID_PRESSURE_LM] =
le16_to_cpu(buf[HUION_PRM_PRESSURE_LM]);
resolution = le16_to_cpu(buf[HUION_PRM_RESOLUTION]);
if (resolution == 0) {
params[HUION_PH_ID_X_PM] = 0;
params[HUION_PH_ID_Y_PM] = 0;
} else {
params[HUION_PH_ID_X_PM] = params[HUION_PH_ID_X_LM] *
1000 / resolution;
params[HUION_PH_ID_Y_PM] = params[HUION_PH_ID_Y_LM] *
1000 / resolution;
}
/* Allocate fixed report descriptor */
drvdata->rdesc = devm_kmalloc(&hdev->dev,
sizeof(huion_tablet_rdesc_template),
GFP_KERNEL);
if (drvdata->rdesc == NULL) {
hid_err(hdev, "failed to allocate fixed rdesc\n");
rc = -ENOMEM;
goto cleanup;
}
drvdata->rsize = sizeof(huion_tablet_rdesc_template);
/* Format fixed report descriptor */
memcpy(drvdata->rdesc, huion_tablet_rdesc_template,
drvdata->rsize);
for (p = drvdata->rdesc;
p <= drvdata->rdesc + drvdata->rsize - 4;) {
if (p[0] == 0xFE && p[1] == 0xED && p[2] == 0x1D &&
p[3] < sizeof(params)) {
v = params[p[3]];
put_unaligned(cpu_to_le32(v), (s32 *)p);
p += 4;
} else {
p++;
}
}
rc = 0;
cleanup:
kfree(buf);
return rc;
}
static int huion_probe(struct hid_device *hdev, const struct hid_device_id *id)
{
int rc;
struct usb_interface *intf = to_usb_interface(hdev->dev.parent);
struct huion_drvdata *drvdata;
/* Allocate and assign driver data */
drvdata = devm_kzalloc(&hdev->dev, sizeof(*drvdata), GFP_KERNEL);
if (drvdata == NULL) {
hid_err(hdev, "failed to allocate driver data\n");
return -ENOMEM;
}
hid_set_drvdata(hdev, drvdata);
switch (id->product) {
case USB_DEVICE_ID_HUION_TABLET:
/* If this is the pen interface */
if (intf->cur_altsetting->desc.bInterfaceNumber == 0) {
rc = huion_tablet_enable(hdev);
if (rc) {
hid_err(hdev, "tablet enabling failed\n");
return rc;
}
}
break;
}
rc = hid_parse(hdev);
if (rc) {
hid_err(hdev, "parse failed\n");
return rc;
}
rc = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
if (rc) {
hid_err(hdev, "hw start failed\n");
return rc;
}
return 0;
}
static int huion_raw_event(struct hid_device *hdev, struct hid_report *report,
u8 *data, int size)
{
struct usb_interface *intf = to_usb_interface(hdev->dev.parent);
/* If this is a pen input report */
if (intf->cur_altsetting->desc.bInterfaceNumber == 0 &&
report->type == HID_INPUT_REPORT &&
report->id == 0x07 && size >= 2)
/* Invert the in-range bit */
data[1] ^= 0x40;
return 0;
}
static const struct hid_device_id huion_devices[] = {
{ HID_USB_DEVICE(USB_VENDOR_ID_HUION, USB_DEVICE_ID_HUION_TABLET) },
{ HID_USB_DEVICE(USB_VENDOR_ID_UCLOGIC, USB_DEVICE_ID_HUION_TABLET) },
{ }
};
MODULE_DEVICE_TABLE(hid, huion_devices);
static struct hid_driver huion_driver = {
.name = "huion",
.id_table = huion_devices,
.probe = huion_probe,
.report_fixup = huion_report_fixup,
.raw_event = huion_raw_event,
};
module_hid_driver(huion_driver);
MODULE_AUTHOR("Martin Rusko");
MODULE_DESCRIPTION("Huion HID driver");
MODULE_LICENSE("GPL");
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