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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) IBM Corporation 2020
*/
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/input.h>
#include <linux/kernel.h>
#include <linux/limits.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/spinlock.h>
#define DEVICE_NAME "ibm-panel"
#define PANEL_KEYCODES_COUNT 3
struct ibm_panel {
u8 idx;
u8 command[11];
u32 keycodes[PANEL_KEYCODES_COUNT];
spinlock_t lock; /* protects writes to idx and command */
struct input_dev *input;
};
static u8 ibm_panel_calculate_checksum(struct ibm_panel *panel)
{
u8 chksum;
u16 sum = 0;
unsigned int i;
for (i = 0; i < sizeof(panel->command) - 1; ++i) {
sum += panel->command[i];
if (sum & 0xff00) {
sum &= 0xff;
sum++;
}
}
chksum = sum & 0xff;
chksum = ~chksum;
chksum++;
return chksum;
}
static void ibm_panel_process_command(struct ibm_panel *panel)
{
u8 button;
u8 chksum;
if (panel->command[0] != 0xff && panel->command[1] != 0xf0) {
dev_dbg(&panel->input->dev, "command invalid: %02x %02x\n",
panel->command[0], panel->command[1]);
return;
}
chksum = ibm_panel_calculate_checksum(panel);
if (chksum != panel->command[sizeof(panel->command) - 1]) {
dev_dbg(&panel->input->dev,
"command failed checksum: %u != %u\n", chksum,
panel->command[sizeof(panel->command) - 1]);
return;
}
button = panel->command[2] & 0xf;
if (button < PANEL_KEYCODES_COUNT) {
input_report_key(panel->input, panel->keycodes[button],
!(panel->command[2] & 0x80));
input_sync(panel->input);
} else {
dev_dbg(&panel->input->dev, "unknown button %u\n",
button);
}
}
static int ibm_panel_i2c_slave_cb(struct i2c_client *client,
enum i2c_slave_event event, u8 *val)
{
struct ibm_panel *panel = i2c_get_clientdata(client);
dev_dbg(&panel->input->dev, "event: %u data: %02x\n", event, *val);
guard(spinlock_irqsave)(&panel->lock);
switch (event) {
case I2C_SLAVE_STOP:
if (panel->idx == sizeof(panel->command))
ibm_panel_process_command(panel);
else
dev_dbg(&panel->input->dev,
"command incorrect size %u\n", panel->idx);
fallthrough;
case I2C_SLAVE_WRITE_REQUESTED:
panel->idx = 0;
break;
case I2C_SLAVE_WRITE_RECEIVED:
if (panel->idx < sizeof(panel->command))
panel->command[panel->idx++] = *val;
else
/*
* The command is too long and therefore invalid, so set the index
* to it's largest possible value. When a STOP is finally received,
* the command will be rejected upon processing.
*/
panel->idx = U8_MAX;
break;
case I2C_SLAVE_READ_REQUESTED:
case I2C_SLAVE_READ_PROCESSED:
*val = 0xff;
break;
default:
break;
}
return 0;
}
static int ibm_panel_probe(struct i2c_client *client)
{
struct ibm_panel *panel;
int i;
int error;
panel = devm_kzalloc(&client->dev, sizeof(*panel), GFP_KERNEL);
if (!panel)
return -ENOMEM;
spin_lock_init(&panel->lock);
panel->input = devm_input_allocate_device(&client->dev);
if (!panel->input)
return -ENOMEM;
panel->input->name = client->name;
panel->input->id.bustype = BUS_I2C;
error = device_property_read_u32_array(&client->dev,
"linux,keycodes",
panel->keycodes,
PANEL_KEYCODES_COUNT);
if (error) {
/*
* Use gamepad buttons as defaults for compatibility with
* existing applications.
*/
panel->keycodes[0] = BTN_NORTH;
panel->keycodes[1] = BTN_SOUTH;
panel->keycodes[2] = BTN_SELECT;
}
for (i = 0; i < PANEL_KEYCODES_COUNT; ++i)
input_set_capability(panel->input, EV_KEY, panel->keycodes[i]);
error = input_register_device(panel->input);
if (error) {
dev_err(&client->dev,
"Failed to register input device: %d\n", error);
return error;
}
i2c_set_clientdata(client, panel);
error = i2c_slave_register(client, ibm_panel_i2c_slave_cb);
if (error) {
dev_err(&client->dev,
"Failed to register as i2c slave: %d\n", error);
return error;
}
return 0;
}
static void ibm_panel_remove(struct i2c_client *client)
{
i2c_slave_unregister(client);
}
static const struct of_device_id ibm_panel_match[] = {
{ .compatible = "ibm,op-panel" },
{ }
};
MODULE_DEVICE_TABLE(of, ibm_panel_match);
static struct i2c_driver ibm_panel_driver = {
.driver = {
.name = DEVICE_NAME,
.of_match_table = ibm_panel_match,
},
.probe = ibm_panel_probe,
.remove = ibm_panel_remove,
};
module_i2c_driver(ibm_panel_driver);
MODULE_AUTHOR("Eddie James <eajames@linux.ibm.com>");
MODULE_DESCRIPTION("IBM Operation Panel Driver");
MODULE_LICENSE("GPL");
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