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// SPDX-License-Identifier: GPL-2.0-only
/*
* Amstrad E3 (Delta) keyboard port driver
*
* Copyright (c) 2006 Matt Callow
* Copyright (c) 2010 Janusz Krzysztofik
*
* Thanks to Cliff Lawson for his help
*
* The Amstrad Delta keyboard (aka mailboard) uses normal PC-AT style serial
* transmission. The keyboard port is formed of two GPIO lines, for clock
* and data. Due to strict timing requirements of the interface,
* the serial data stream is read and processed by a FIQ handler.
* The resulting words are fetched by this driver from a circular buffer.
*
* Standard AT keyboard driver (atkbd) is used for handling the keyboard data.
* However, when used with the E3 mailboard that producecs non-standard
* scancodes, a custom key table must be prepared and loaded from userspace.
*/
#include <linux/irq.h>
#include <linux/platform_data/ams-delta-fiq.h>
#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>
#include <linux/serio.h>
#include <linux/slab.h>
#include <linux/module.h>
#define DRIVER_NAME "ams-delta-serio"
MODULE_AUTHOR("Matt Callow");
MODULE_DESCRIPTION("AMS Delta (E3) keyboard port driver");
MODULE_LICENSE("GPL");
struct ams_delta_serio {
struct serio *serio;
struct regulator *vcc;
unsigned int *fiq_buffer;
};
static int check_data(struct serio *serio, int data)
{
int i, parity = 0;
/* check valid stop bit */
if (!(data & 0x400)) {
dev_warn(&serio->dev, "invalid stop bit, data=0x%X\n", data);
return SERIO_FRAME;
}
/* calculate the parity */
for (i = 1; i < 10; i++) {
if (data & (1 << i))
parity++;
}
/* it should be odd */
if (!(parity & 0x01)) {
dev_warn(&serio->dev,
"parity check failed, data=0x%X parity=0x%X\n", data,
parity);
return SERIO_PARITY;
}
return 0;
}
static irqreturn_t ams_delta_serio_interrupt(int irq, void *dev_id)
{
struct ams_delta_serio *priv = dev_id;
int *circ_buff = &priv->fiq_buffer[FIQ_CIRC_BUFF];
int data, dfl;
u8 scancode;
priv->fiq_buffer[FIQ_IRQ_PEND] = 0;
/*
* Read data from the circular buffer, check it
* and then pass it on the serio
*/
while (priv->fiq_buffer[FIQ_KEYS_CNT] > 0) {
data = circ_buff[priv->fiq_buffer[FIQ_HEAD_OFFSET]++];
priv->fiq_buffer[FIQ_KEYS_CNT]--;
if (priv->fiq_buffer[FIQ_HEAD_OFFSET] ==
priv->fiq_buffer[FIQ_BUF_LEN])
priv->fiq_buffer[FIQ_HEAD_OFFSET] = 0;
dfl = check_data(priv->serio, data);
scancode = (u8) (data >> 1) & 0xFF;
serio_interrupt(priv->serio, scancode, dfl);
}
return IRQ_HANDLED;
}
static int ams_delta_serio_open(struct serio *serio)
{
struct ams_delta_serio *priv = serio->port_data;
/* enable keyboard */
return regulator_enable(priv->vcc);
}
static void ams_delta_serio_close(struct serio *serio)
{
struct ams_delta_serio *priv = serio->port_data;
/* disable keyboard */
regulator_disable(priv->vcc);
}
static int ams_delta_serio_init(struct platform_device *pdev)
{
struct ams_delta_serio *priv;
struct serio *serio;
int irq, err;
priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->fiq_buffer = pdev->dev.platform_data;
if (!priv->fiq_buffer)
return -EINVAL;
priv->vcc = devm_regulator_get(&pdev->dev, "vcc");
if (IS_ERR(priv->vcc)) {
err = PTR_ERR(priv->vcc);
dev_err(&pdev->dev, "regulator request failed (%d)\n", err);
/*
* When running on a non-dt platform and requested regulator
* is not available, devm_regulator_get() never returns
* -EPROBE_DEFER as it is not able to justify if the regulator
* may still appear later. On the other hand, the board can
* still set full constriants flag at late_initcall in order
* to instruct devm_regulator_get() to returnn a dummy one
* if sufficient. Hence, if we get -ENODEV here, let's convert
* it to -EPROBE_DEFER and wait for the board to decide or
* let Deferred Probe infrastructure handle this error.
*/
if (err == -ENODEV)
err = -EPROBE_DEFER;
return err;
}
irq = platform_get_irq(pdev, 0);
if (irq < 0)
return -ENXIO;
err = devm_request_irq(&pdev->dev, irq, ams_delta_serio_interrupt,
IRQ_TYPE_EDGE_RISING, DRIVER_NAME, priv);
if (err < 0) {
dev_err(&pdev->dev, "IRQ request failed (%d)\n", err);
return err;
}
serio = kzalloc(sizeof(*serio), GFP_KERNEL);
if (!serio)
return -ENOMEM;
priv->serio = serio;
serio->id.type = SERIO_8042;
serio->open = ams_delta_serio_open;
serio->close = ams_delta_serio_close;
strscpy(serio->name, "AMS DELTA keyboard adapter", sizeof(serio->name));
strscpy(serio->phys, dev_name(&pdev->dev), sizeof(serio->phys));
serio->dev.parent = &pdev->dev;
serio->port_data = priv;
serio_register_port(serio);
platform_set_drvdata(pdev, priv);
dev_info(&serio->dev, "%s\n", serio->name);
return 0;
}
static int ams_delta_serio_exit(struct platform_device *pdev)
{
struct ams_delta_serio *priv = platform_get_drvdata(pdev);
serio_unregister_port(priv->serio);
return 0;
}
static struct platform_driver ams_delta_serio_driver = {
.probe = ams_delta_serio_init,
.remove = ams_delta_serio_exit,
.driver = {
.name = DRIVER_NAME
},
};
module_platform_driver(ams_delta_serio_driver);
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