456 строки
11 KiB
C
456 строки
11 KiB
C
/*
|
|
* GPIO based serio bus driver for bit banging the PS/2 protocol
|
|
*
|
|
* Author: Danilo Krummrich <danilokrummrich@dk-develop.de>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*/
|
|
|
|
#include <linux/gpio/consumer.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/module.h>
|
|
#include <linux/serio.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/platform_device.h>
|
|
#include <linux/workqueue.h>
|
|
#include <linux/completion.h>
|
|
#include <linux/mutex.h>
|
|
#include <linux/preempt.h>
|
|
#include <linux/property.h>
|
|
#include <linux/of.h>
|
|
#include <linux/jiffies.h>
|
|
#include <linux/delay.h>
|
|
|
|
#define DRIVER_NAME "ps2-gpio"
|
|
|
|
#define PS2_MODE_RX 0
|
|
#define PS2_MODE_TX 1
|
|
|
|
#define PS2_START_BIT 0
|
|
#define PS2_DATA_BIT0 1
|
|
#define PS2_DATA_BIT1 2
|
|
#define PS2_DATA_BIT2 3
|
|
#define PS2_DATA_BIT3 4
|
|
#define PS2_DATA_BIT4 5
|
|
#define PS2_DATA_BIT5 6
|
|
#define PS2_DATA_BIT6 7
|
|
#define PS2_DATA_BIT7 8
|
|
#define PS2_PARITY_BIT 9
|
|
#define PS2_STOP_BIT 10
|
|
#define PS2_TX_TIMEOUT 11
|
|
#define PS2_ACK_BIT 12
|
|
|
|
#define PS2_DEV_RET_ACK 0xfa
|
|
#define PS2_DEV_RET_NACK 0xfe
|
|
|
|
#define PS2_CMD_RESEND 0xfe
|
|
|
|
struct ps2_gpio_data {
|
|
struct device *dev;
|
|
struct serio *serio;
|
|
unsigned char mode;
|
|
struct gpio_desc *gpio_clk;
|
|
struct gpio_desc *gpio_data;
|
|
bool write_enable;
|
|
int irq;
|
|
unsigned char rx_cnt;
|
|
unsigned char rx_byte;
|
|
unsigned char tx_cnt;
|
|
unsigned char tx_byte;
|
|
struct completion tx_done;
|
|
struct mutex tx_mutex;
|
|
struct delayed_work tx_work;
|
|
};
|
|
|
|
static int ps2_gpio_open(struct serio *serio)
|
|
{
|
|
struct ps2_gpio_data *drvdata = serio->port_data;
|
|
|
|
enable_irq(drvdata->irq);
|
|
return 0;
|
|
}
|
|
|
|
static void ps2_gpio_close(struct serio *serio)
|
|
{
|
|
struct ps2_gpio_data *drvdata = serio->port_data;
|
|
|
|
flush_delayed_work(&drvdata->tx_work);
|
|
disable_irq(drvdata->irq);
|
|
}
|
|
|
|
static int __ps2_gpio_write(struct serio *serio, unsigned char val)
|
|
{
|
|
struct ps2_gpio_data *drvdata = serio->port_data;
|
|
|
|
disable_irq_nosync(drvdata->irq);
|
|
gpiod_direction_output(drvdata->gpio_clk, 0);
|
|
|
|
drvdata->mode = PS2_MODE_TX;
|
|
drvdata->tx_byte = val;
|
|
|
|
schedule_delayed_work(&drvdata->tx_work, usecs_to_jiffies(200));
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int ps2_gpio_write(struct serio *serio, unsigned char val)
|
|
{
|
|
struct ps2_gpio_data *drvdata = serio->port_data;
|
|
int ret = 0;
|
|
|
|
if (in_task()) {
|
|
mutex_lock(&drvdata->tx_mutex);
|
|
__ps2_gpio_write(serio, val);
|
|
if (!wait_for_completion_timeout(&drvdata->tx_done,
|
|
msecs_to_jiffies(10000)))
|
|
ret = SERIO_TIMEOUT;
|
|
mutex_unlock(&drvdata->tx_mutex);
|
|
} else {
|
|
__ps2_gpio_write(serio, val);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void ps2_gpio_tx_work_fn(struct work_struct *work)
|
|
{
|
|
struct delayed_work *dwork = to_delayed_work(work);
|
|
struct ps2_gpio_data *drvdata = container_of(dwork,
|
|
struct ps2_gpio_data,
|
|
tx_work);
|
|
|
|
enable_irq(drvdata->irq);
|
|
gpiod_direction_output(drvdata->gpio_data, 0);
|
|
gpiod_direction_input(drvdata->gpio_clk);
|
|
}
|
|
|
|
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;
|
|
|
|
byte = drvdata->rx_byte;
|
|
cnt = drvdata->rx_cnt;
|
|
|
|
if (old_jiffies == 0)
|
|
old_jiffies = jiffies;
|
|
|
|
if ((jiffies - old_jiffies) > usecs_to_jiffies(100)) {
|
|
dev_err(drvdata->dev,
|
|
"RX: timeout, probably we missed an interrupt\n");
|
|
goto err;
|
|
}
|
|
old_jiffies = jiffies;
|
|
|
|
data = gpiod_get_value(drvdata->gpio_data);
|
|
if (unlikely(data < 0)) {
|
|
dev_err(drvdata->dev, "RX: failed to get data gpio val: %d\n",
|
|
data);
|
|
goto err;
|
|
}
|
|
|
|
switch (cnt) {
|
|
case PS2_START_BIT:
|
|
/* start bit should be low */
|
|
if (unlikely(data)) {
|
|
dev_err(drvdata->dev, "RX: start bit should be low\n");
|
|
goto err;
|
|
}
|
|
break;
|
|
case PS2_DATA_BIT0:
|
|
case PS2_DATA_BIT1:
|
|
case PS2_DATA_BIT2:
|
|
case PS2_DATA_BIT3:
|
|
case PS2_DATA_BIT4:
|
|
case PS2_DATA_BIT5:
|
|
case PS2_DATA_BIT6:
|
|
case PS2_DATA_BIT7:
|
|
/* processing data bits */
|
|
if (data)
|
|
byte |= (data << (cnt - 1));
|
|
break;
|
|
case PS2_PARITY_BIT:
|
|
/* check odd parity */
|
|
if (!((hweight8(byte) & 1) ^ data)) {
|
|
rxflags |= SERIO_PARITY;
|
|
dev_warn(drvdata->dev, "RX: parity error\n");
|
|
if (!drvdata->write_enable)
|
|
goto err;
|
|
}
|
|
|
|
/* Do not send spurious ACK's and NACK's when write fn is
|
|
* not provided.
|
|
*/
|
|
if (!drvdata->write_enable) {
|
|
if (byte == PS2_DEV_RET_NACK)
|
|
goto err;
|
|
else if (byte == PS2_DEV_RET_ACK)
|
|
break;
|
|
}
|
|
|
|
/* 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
|
|
* the stop bit. When missing both, data is lost.
|
|
*/
|
|
serio_interrupt(drvdata->serio, byte, rxflags);
|
|
dev_dbg(drvdata->dev, "RX: sending byte 0x%x\n", byte);
|
|
break;
|
|
case PS2_STOP_BIT:
|
|
/* stop bit should be high */
|
|
if (unlikely(!data)) {
|
|
dev_err(drvdata->dev, "RX: stop bit should be high\n");
|
|
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");
|
|
goto err;
|
|
}
|
|
|
|
cnt++;
|
|
goto end; /* success */
|
|
|
|
err:
|
|
cnt = byte = 0;
|
|
old_jiffies = 0;
|
|
__ps2_gpio_write(drvdata->serio, PS2_CMD_RESEND);
|
|
end:
|
|
drvdata->rx_cnt = cnt;
|
|
drvdata->rx_byte = byte;
|
|
return IRQ_HANDLED;
|
|
}
|
|
|
|
static irqreturn_t ps2_gpio_irq_tx(struct ps2_gpio_data *drvdata)
|
|
{
|
|
unsigned char byte, cnt;
|
|
int data;
|
|
static unsigned long old_jiffies;
|
|
|
|
cnt = drvdata->tx_cnt;
|
|
byte = drvdata->tx_byte;
|
|
|
|
if (old_jiffies == 0)
|
|
old_jiffies = jiffies;
|
|
|
|
if ((jiffies - old_jiffies) > usecs_to_jiffies(100)) {
|
|
dev_err(drvdata->dev,
|
|
"TX: timeout, probably we missed an interrupt\n");
|
|
goto err;
|
|
}
|
|
old_jiffies = jiffies;
|
|
|
|
switch (cnt) {
|
|
case PS2_START_BIT:
|
|
/* should never happen */
|
|
dev_err(drvdata->dev,
|
|
"TX: start bit should have been sent already\n");
|
|
goto err;
|
|
case PS2_DATA_BIT0:
|
|
case PS2_DATA_BIT1:
|
|
case PS2_DATA_BIT2:
|
|
case PS2_DATA_BIT3:
|
|
case PS2_DATA_BIT4:
|
|
case PS2_DATA_BIT5:
|
|
case PS2_DATA_BIT6:
|
|
case PS2_DATA_BIT7:
|
|
data = byte & BIT(cnt - 1);
|
|
gpiod_set_value(drvdata->gpio_data, data);
|
|
break;
|
|
case PS2_PARITY_BIT:
|
|
/* do odd parity */
|
|
data = !(hweight8(byte) & 1);
|
|
gpiod_set_value(drvdata->gpio_data, data);
|
|
break;
|
|
case PS2_STOP_BIT:
|
|
/* release data line to generate stop bit */
|
|
gpiod_direction_input(drvdata->gpio_data);
|
|
break;
|
|
case PS2_TX_TIMEOUT:
|
|
/* Devices generate one extra clock pulse before sending the
|
|
* acknowledgment.
|
|
*/
|
|
break;
|
|
case PS2_ACK_BIT:
|
|
gpiod_direction_input(drvdata->gpio_data);
|
|
data = gpiod_get_value(drvdata->gpio_data);
|
|
if (data) {
|
|
dev_warn(drvdata->dev, "TX: received NACK, retry\n");
|
|
goto err;
|
|
}
|
|
|
|
drvdata->mode = PS2_MODE_RX;
|
|
complete(&drvdata->tx_done);
|
|
|
|
cnt = 1;
|
|
old_jiffies = 0;
|
|
goto end; /* success */
|
|
default:
|
|
/* Probably we missed the stop bit. Therefore we release data
|
|
* line and try again.
|
|
*/
|
|
gpiod_direction_input(drvdata->gpio_data);
|
|
dev_err(drvdata->dev, "TX: got out of sync with the device\n");
|
|
goto err;
|
|
}
|
|
|
|
cnt++;
|
|
goto end; /* success */
|
|
|
|
err:
|
|
cnt = 1;
|
|
old_jiffies = 0;
|
|
gpiod_direction_input(drvdata->gpio_data);
|
|
__ps2_gpio_write(drvdata->serio, drvdata->tx_byte);
|
|
end:
|
|
drvdata->tx_cnt = cnt;
|
|
return IRQ_HANDLED;
|
|
}
|
|
|
|
static irqreturn_t ps2_gpio_irq(int irq, void *dev_id)
|
|
{
|
|
struct ps2_gpio_data *drvdata = dev_id;
|
|
|
|
return drvdata->mode ? ps2_gpio_irq_tx(drvdata) :
|
|
ps2_gpio_irq_rx(drvdata);
|
|
}
|
|
|
|
static int ps2_gpio_get_props(struct device *dev,
|
|
struct ps2_gpio_data *drvdata)
|
|
{
|
|
drvdata->gpio_data = devm_gpiod_get(dev, "data", GPIOD_IN);
|
|
if (IS_ERR(drvdata->gpio_data)) {
|
|
dev_err(dev, "failed to request data gpio: %ld",
|
|
PTR_ERR(drvdata->gpio_data));
|
|
return PTR_ERR(drvdata->gpio_data);
|
|
}
|
|
|
|
drvdata->gpio_clk = devm_gpiod_get(dev, "clk", GPIOD_IN);
|
|
if (IS_ERR(drvdata->gpio_clk)) {
|
|
dev_err(dev, "failed to request clock gpio: %ld",
|
|
PTR_ERR(drvdata->gpio_clk));
|
|
return PTR_ERR(drvdata->gpio_clk);
|
|
}
|
|
|
|
drvdata->write_enable = device_property_read_bool(dev,
|
|
"write-enable");
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int ps2_gpio_probe(struct platform_device *pdev)
|
|
{
|
|
struct ps2_gpio_data *drvdata;
|
|
struct serio *serio;
|
|
struct device *dev = &pdev->dev;
|
|
int error;
|
|
|
|
drvdata = devm_kzalloc(dev, sizeof(struct ps2_gpio_data), GFP_KERNEL);
|
|
serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
|
|
if (!drvdata || !serio) {
|
|
error = -ENOMEM;
|
|
goto err_free_serio;
|
|
}
|
|
|
|
error = ps2_gpio_get_props(dev, drvdata);
|
|
if (error)
|
|
goto err_free_serio;
|
|
|
|
if (gpiod_cansleep(drvdata->gpio_data) ||
|
|
gpiod_cansleep(drvdata->gpio_clk)) {
|
|
dev_err(dev, "GPIO data or clk are connected via slow bus\n");
|
|
error = -EINVAL;
|
|
goto err_free_serio;
|
|
}
|
|
|
|
drvdata->irq = platform_get_irq(pdev, 0);
|
|
if (drvdata->irq < 0) {
|
|
dev_err(dev, "failed to get irq from platform resource: %d\n",
|
|
drvdata->irq);
|
|
error = drvdata->irq;
|
|
goto err_free_serio;
|
|
}
|
|
|
|
error = devm_request_irq(dev, drvdata->irq, ps2_gpio_irq,
|
|
IRQF_NO_THREAD, DRIVER_NAME, drvdata);
|
|
if (error) {
|
|
dev_err(dev, "failed to request irq %d: %d\n",
|
|
drvdata->irq, error);
|
|
goto err_free_serio;
|
|
}
|
|
|
|
/* Keep irq disabled until serio->open is called. */
|
|
disable_irq(drvdata->irq);
|
|
|
|
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
|
|
* work because of the tough timings.
|
|
*/
|
|
serio->write = drvdata->write_enable ? ps2_gpio_write : NULL;
|
|
serio->port_data = drvdata;
|
|
serio->dev.parent = dev;
|
|
strlcpy(serio->name, dev_name(dev), sizeof(serio->name));
|
|
strlcpy(serio->phys, dev_name(dev), sizeof(serio->phys));
|
|
|
|
drvdata->serio = serio;
|
|
drvdata->dev = dev;
|
|
drvdata->mode = PS2_MODE_RX;
|
|
|
|
/* Tx count always starts at 1, as the start bit is sent implicitly by
|
|
* host-to-device communication initialization.
|
|
*/
|
|
drvdata->tx_cnt = 1;
|
|
|
|
INIT_DELAYED_WORK(&drvdata->tx_work, ps2_gpio_tx_work_fn);
|
|
init_completion(&drvdata->tx_done);
|
|
mutex_init(&drvdata->tx_mutex);
|
|
|
|
serio_register_port(serio);
|
|
platform_set_drvdata(pdev, drvdata);
|
|
|
|
return 0; /* success */
|
|
|
|
err_free_serio:
|
|
kfree(serio);
|
|
return error;
|
|
}
|
|
|
|
static int ps2_gpio_remove(struct platform_device *pdev)
|
|
{
|
|
struct ps2_gpio_data *drvdata = platform_get_drvdata(pdev);
|
|
|
|
serio_unregister_port(drvdata->serio);
|
|
return 0;
|
|
}
|
|
|
|
#if defined(CONFIG_OF)
|
|
static const struct of_device_id ps2_gpio_match[] = {
|
|
{ .compatible = "ps2-gpio", },
|
|
{ },
|
|
};
|
|
MODULE_DEVICE_TABLE(of, ps2_gpio_match);
|
|
#endif
|
|
|
|
static struct platform_driver ps2_gpio_driver = {
|
|
.probe = ps2_gpio_probe,
|
|
.remove = ps2_gpio_remove,
|
|
.driver = {
|
|
.name = DRIVER_NAME,
|
|
.of_match_table = of_match_ptr(ps2_gpio_match),
|
|
},
|
|
};
|
|
module_platform_driver(ps2_gpio_driver);
|
|
|
|
MODULE_AUTHOR("Danilo Krummrich <danilokrummrich@dk-develop.de>");
|
|
MODULE_DESCRIPTION("GPIO PS2 driver");
|
|
MODULE_LICENSE("GPL v2");
|