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Input: elo - fix checksum calculation
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Fix 10-byte protocol checksum calculation and do not discard packet early
unless it is missing lead in byte.

Signed-off-by: Shaun Jackman <sjackman@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
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Shaun Jackman authored and Dmitry Torokhov committed Aug 5, 2006
1 parent 6b50d8b commit 1ce316e
Showing 1 changed file with 29 additions and 26 deletions.
55 changes: 29 additions & 26 deletions drivers/input/touchscreen/elo.c
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Original file line number Diff line number Diff line change
Expand Up @@ -34,7 +34,11 @@ MODULE_LICENSE("GPL");
* Definitions & global arrays.
*/

#define ELO_MAX_LENGTH 10
#define ELO_MAX_LENGTH 10

#define ELO10_LEAD_BYTE 'U'

#define ELO10_TOUCH_PACKET 'T'

/*
* Per-touchscreen data.
Expand All @@ -50,44 +54,43 @@ struct elo {
char phys[32];
};

static void elo_process_data_10(struct elo* elo, unsigned char data, struct pt_regs *regs)
static void elo_process_data_10(struct elo *elo, unsigned char data, struct pt_regs *regs)
{
struct input_dev *dev = elo->dev;

elo->csum += elo->data[elo->idx] = data;

elo->data[elo->idx] = data;
switch (elo->idx++) {

case 0:
if (data != 'U') {
elo->idx = 0;
elo->csum = 0;
}
break;

case 1:
if (data != 'T') {
elo->csum = 0xaa;
if (data != ELO10_LEAD_BYTE) {
pr_debug("elo: unsynchronized data: 0x%02x\n", data);
elo->idx = 0;
elo->csum = 0;
}
break;

case 9:
if (elo->csum) {
input_regs(dev, regs);
input_report_abs(dev, ABS_X, (elo->data[4] << 8) | elo->data[3]);
input_report_abs(dev, ABS_Y, (elo->data[6] << 8) | elo->data[5]);
input_report_abs(dev, ABS_PRESSURE, (elo->data[8] << 8) | elo->data[7]);
input_report_key(dev, BTN_TOUCH, elo->data[8] || elo->data[7]);
input_sync(dev);
}
elo->idx = 0;
elo->csum = 0;
if (data != elo->csum) {
pr_debug("elo: bad checksum: 0x%02x, expected 0x%02x\n",
data, elo->csum);
break;
}
if (elo->data[1] != ELO10_TOUCH_PACKET) {
pr_debug(elo: "unexpected packet: 0x%02x\n", elo->data[1]);
break;
}
input_regs(dev, regs);
input_report_abs(dev, ABS_X, (elo->data[4] << 8) | elo->data[3]);
input_report_abs(dev, ABS_Y, (elo->data[6] << 8) | elo->data[5]);
input_report_abs(dev, ABS_PRESSURE, (elo->data[8] << 8) | elo->data[7]);
input_report_key(dev, BTN_TOUCH, elo->data[8] || elo->data[7]);
input_sync(dev);
break;
}
elo->csum += data;
}

static void elo_process_data_6(struct elo* elo, unsigned char data, struct pt_regs *regs)
static void elo_process_data_6(struct elo *elo, unsigned char data, struct pt_regs *regs)
{
struct input_dev *dev = elo->dev;

Expand Down Expand Up @@ -135,7 +138,7 @@ static void elo_process_data_6(struct elo* elo, unsigned char data, struct pt_re
}
}

static void elo_process_data_3(struct elo* elo, unsigned char data, struct pt_regs *regs)
static void elo_process_data_3(struct elo *elo, unsigned char data, struct pt_regs *regs)
{
struct input_dev *dev = elo->dev;

Expand All @@ -161,7 +164,7 @@ static void elo_process_data_3(struct elo* elo, unsigned char data, struct pt_re
static irqreturn_t elo_interrupt(struct serio *serio,
unsigned char data, unsigned int flags, struct pt_regs *regs)
{
struct elo* elo = serio_get_drvdata(serio);
struct elo *elo = serio_get_drvdata(serio);

switch(elo->id) {
case 0:
Expand Down

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