summaryrefslogtreecommitdiff
path: root/drivers/input/serio
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/input/serio')
-rw-r--r--drivers/input/serio/ps2-gpio.c102
1 files changed, 82 insertions, 20 deletions
diff --git a/drivers/input/serio/ps2-gpio.c b/drivers/input/serio/ps2-gpio.c
index 1682125fba11..f1b7313a0866 100644
--- a/drivers/input/serio/ps2-gpio.c
+++ b/drivers/input/serio/ps2-gpio.c
@@ -19,6 +19,7 @@
#include <linux/of.h>
#include <linux/jiffies.h>
#include <linux/delay.h>
+#include <linux/timekeeping.h>
#define DRIVER_NAME "ps2-gpio"
@@ -44,6 +45,30 @@
#define PS2_CMD_RESEND 0xfe
+/*
+ * The PS2 protocol specifies a clock frequency between 10kHz and 16.7kHz,
+ * therefore the maximal interrupt interval should be 100us and the minimum
+ * interrupt interval should be ~60us. Let's allow +/- 20us for frequency
+ * deviations and interrupt latency.
+ *
+ * The data line must be samples after ~30us to 50us after the falling edge,
+ * since the device updates the data line at the rising edge.
+ *
+ * ___ ______ ______ ______ ___
+ * \ / \ / \ / \ /
+ * \ / \ / \ / \ /
+ * \______/ \______/ \______/ \______/
+ *
+ * |-----------------| |--------|
+ * 60us/100us 30us/50us
+ */
+#define PS2_CLK_FREQ_MIN_HZ 10000
+#define PS2_CLK_FREQ_MAX_HZ 16700
+#define PS2_CLK_MIN_INTERVAL_US ((1000 * 1000) / PS2_CLK_FREQ_MAX_HZ)
+#define PS2_CLK_MAX_INTERVAL_US ((1000 * 1000) / PS2_CLK_FREQ_MIN_HZ)
+#define PS2_IRQ_MIN_INTERVAL_US (PS2_CLK_MIN_INTERVAL_US - 20)
+#define PS2_IRQ_MAX_INTERVAL_US (PS2_CLK_MAX_INTERVAL_US + 20)
+
struct ps2_gpio_data {
struct device *dev;
struct serio *serio;
@@ -52,6 +77,8 @@ struct ps2_gpio_data {
struct gpio_desc *gpio_data;
bool write_enable;
int irq;
+ ktime_t t_irq_now;
+ ktime_t t_irq_last;
struct {
unsigned char cnt;
unsigned char byte;
@@ -59,6 +86,8 @@ struct ps2_gpio_data {
struct {
unsigned char cnt;
unsigned char byte;
+ ktime_t t_xfer_start;
+ ktime_t t_xfer_end;
struct completion complete;
struct mutex mutex;
struct delayed_work work;
@@ -69,6 +98,9 @@ static int ps2_gpio_open(struct serio *serio)
{
struct ps2_gpio_data *drvdata = serio->port_data;
+ drvdata->t_irq_last = 0;
+ drvdata->tx.t_xfer_end = 0;
+
enable_irq(drvdata->irq);
return 0;
}
@@ -122,6 +154,7 @@ static void ps2_gpio_tx_work_fn(struct work_struct *work)
struct ps2_gpio_data,
tx.work);
+ drvdata->tx.t_xfer_start = ktime_get();
enable_irq(drvdata->irq);
gpiod_direction_output(drvdata->gpio_data, 0);
gpiod_direction_input(drvdata->gpio_clk);
@@ -132,20 +165,31 @@ static irqreturn_t ps2_gpio_irq_rx(struct ps2_gpio_data *drvdata)
unsigned char byte, cnt;
int data;
int rxflags = 0;
- static unsigned long old_jiffies;
+ s64 us_delta;
byte = drvdata->rx.byte;
cnt = drvdata->rx.cnt;
- if (old_jiffies == 0)
- old_jiffies = jiffies;
+ drvdata->t_irq_now = ktime_get();
+
+ /*
+ * We need to consider spurious interrupts happening right after
+ * a TX xfer finished.
+ */
+ us_delta = ktime_us_delta(drvdata->t_irq_now, drvdata->tx.t_xfer_end);
+ if (unlikely(us_delta < PS2_IRQ_MIN_INTERVAL_US))
+ goto end;
- if ((jiffies - old_jiffies) > usecs_to_jiffies(100)) {
+ us_delta = ktime_us_delta(drvdata->t_irq_now, drvdata->t_irq_last);
+ if (us_delta > PS2_IRQ_MAX_INTERVAL_US && cnt) {
dev_err(drvdata->dev,
"RX: timeout, probably we missed an interrupt\n");
goto err;
+ } else if (unlikely(us_delta < PS2_IRQ_MIN_INTERVAL_US)) {
+ /* Ignore spurious IRQs. */
+ goto end;
}
- old_jiffies = jiffies;
+ drvdata->t_irq_last = drvdata->t_irq_now;
data = gpiod_get_value(drvdata->gpio_data);
if (unlikely(data < 0)) {
@@ -183,7 +227,8 @@ static irqreturn_t ps2_gpio_irq_rx(struct ps2_gpio_data *drvdata)
goto err;
}
- /* Do not send spurious ACK's and NACK's when write fn is
+ /*
+ * Do not send spurious ACK's and NACK's when write fn is
* not provided.
*/
if (!drvdata->write_enable) {
@@ -193,7 +238,8 @@ static irqreturn_t ps2_gpio_irq_rx(struct ps2_gpio_data *drvdata)
break;
}
- /* Let's send the data without waiting for the stop bit to be
+ /*
+ * Let's send the data without waiting for the stop bit to be
* sent. It may happen that we miss the stop bit. When this
* happens we have no way to recover from this, certainly
* missing the parity bit would be recognized when processing
@@ -209,7 +255,7 @@ static irqreturn_t ps2_gpio_irq_rx(struct ps2_gpio_data *drvdata)
goto err;
}
cnt = byte = 0;
- old_jiffies = 0;
+
goto end; /* success */
default:
dev_err(drvdata->dev, "RX: got out of sync with the device\n");
@@ -221,7 +267,6 @@ static irqreturn_t ps2_gpio_irq_rx(struct ps2_gpio_data *drvdata)
err:
cnt = byte = 0;
- old_jiffies = 0;
__ps2_gpio_write(drvdata->serio, PS2_CMD_RESEND);
end:
drvdata->rx.cnt = cnt;
@@ -233,20 +278,34 @@ static irqreturn_t ps2_gpio_irq_tx(struct ps2_gpio_data *drvdata)
{
unsigned char byte, cnt;
int data;
- static unsigned long old_jiffies;
+ s64 us_delta;
cnt = drvdata->tx.cnt;
byte = drvdata->tx.byte;
- if (old_jiffies == 0)
- old_jiffies = jiffies;
+ drvdata->t_irq_now = ktime_get();
+
+ /*
+ * There might be pending IRQs since we disabled IRQs in
+ * __ps2_gpio_write(). We can expect at least one clock period until
+ * the device generates the first falling edge after releasing the
+ * clock line.
+ */
+ us_delta = ktime_us_delta(drvdata->t_irq_now,
+ drvdata->tx.t_xfer_start);
+ if (unlikely(us_delta < PS2_CLK_MIN_INTERVAL_US))
+ goto end;
- if ((jiffies - old_jiffies) > usecs_to_jiffies(100)) {
+ us_delta = ktime_us_delta(drvdata->t_irq_now, drvdata->t_irq_last);
+ if (us_delta > PS2_IRQ_MAX_INTERVAL_US && cnt > 1) {
dev_err(drvdata->dev,
"TX: timeout, probably we missed an interrupt\n");
goto err;
+ } else if (unlikely(us_delta < PS2_IRQ_MIN_INTERVAL_US)) {
+ /* Ignore spurious IRQs. */
+ goto end;
}
- old_jiffies = jiffies;
+ drvdata->t_irq_last = drvdata->t_irq_now;
switch (cnt) {
case PS2_START_BIT:
@@ -275,7 +334,8 @@ static irqreturn_t ps2_gpio_irq_tx(struct ps2_gpio_data *drvdata)
gpiod_direction_input(drvdata->gpio_data);
break;
case PS2_TX_TIMEOUT:
- /* Devices generate one extra clock pulse before sending the
+ /*
+ * Devices generate one extra clock pulse before sending the
* acknowledgment.
*/
break;
@@ -287,14 +347,15 @@ static irqreturn_t ps2_gpio_irq_tx(struct ps2_gpio_data *drvdata)
goto err;
}
+ drvdata->tx.t_xfer_end = ktime_get();
drvdata->mode = PS2_MODE_RX;
complete(&drvdata->tx.complete);
cnt = 1;
- old_jiffies = 0;
goto end; /* success */
default:
- /* Probably we missed the stop bit. Therefore we release data
+ /*
+ * Probably we missed the stop bit. Therefore we release data
* line and try again.
*/
gpiod_direction_input(drvdata->gpio_data);
@@ -307,7 +368,6 @@ static irqreturn_t ps2_gpio_irq_tx(struct ps2_gpio_data *drvdata)
err:
cnt = 1;
- old_jiffies = 0;
gpiod_direction_input(drvdata->gpio_data);
__ps2_gpio_write(drvdata->serio, drvdata->tx.byte);
end:
@@ -391,7 +451,8 @@ static int ps2_gpio_probe(struct platform_device *pdev)
serio->id.type = SERIO_8042;
serio->open = ps2_gpio_open;
serio->close = ps2_gpio_close;
- /* Write can be enabled in platform/dt data, but possibly it will not
+ /*
+ * Write can be enabled in platform/dt data, but possibly it will not
* work because of the tough timings.
*/
serio->write = drvdata->write_enable ? ps2_gpio_write : NULL;
@@ -404,7 +465,8 @@ static int ps2_gpio_probe(struct platform_device *pdev)
drvdata->dev = dev;
drvdata->mode = PS2_MODE_RX;
- /* Tx count always starts at 1, as the start bit is sent implicitly by
+ /*
+ * Tx count always starts at 1, as the start bit is sent implicitly by
* host-to-device communication initialization.
*/
drvdata->tx.cnt = 1;
generated by cgit v1.2.3 (git 2.39.0) at 2024-12-20 01:34:17 +0300