12e6f34faSEddie James // SPDX-License-Identifier: GPL-2.0-or-later
22e6f34faSEddie James /*
32e6f34faSEddie James * Copyright (C) IBM Corporation 2020
42e6f34faSEddie James */
52e6f34faSEddie James
62e6f34faSEddie James #include <linux/i2c.h>
72e6f34faSEddie James #include <linux/init.h>
82e6f34faSEddie James #include <linux/input.h>
92e6f34faSEddie James #include <linux/kernel.h>
102e6f34faSEddie James #include <linux/limits.h>
112e6f34faSEddie James #include <linux/module.h>
122e6f34faSEddie James #include <linux/of.h>
132e6f34faSEddie James #include <linux/spinlock.h>
142e6f34faSEddie James
152e6f34faSEddie James #define DEVICE_NAME "ibm-panel"
162e6f34faSEddie James #define PANEL_KEYCODES_COUNT 3
172e6f34faSEddie James
182e6f34faSEddie James struct ibm_panel {
192e6f34faSEddie James u8 idx;
202e6f34faSEddie James u8 command[11];
212e6f34faSEddie James u32 keycodes[PANEL_KEYCODES_COUNT];
222e6f34faSEddie James spinlock_t lock; /* protects writes to idx and command */
232e6f34faSEddie James struct input_dev *input;
242e6f34faSEddie James };
252e6f34faSEddie James
ibm_panel_calculate_checksum(struct ibm_panel * panel)262e6f34faSEddie James static u8 ibm_panel_calculate_checksum(struct ibm_panel *panel)
272e6f34faSEddie James {
282e6f34faSEddie James u8 chksum;
292e6f34faSEddie James u16 sum = 0;
302e6f34faSEddie James unsigned int i;
312e6f34faSEddie James
322e6f34faSEddie James for (i = 0; i < sizeof(panel->command) - 1; ++i) {
332e6f34faSEddie James sum += panel->command[i];
342e6f34faSEddie James if (sum & 0xff00) {
352e6f34faSEddie James sum &= 0xff;
362e6f34faSEddie James sum++;
372e6f34faSEddie James }
382e6f34faSEddie James }
392e6f34faSEddie James
402e6f34faSEddie James chksum = sum & 0xff;
412e6f34faSEddie James chksum = ~chksum;
422e6f34faSEddie James chksum++;
432e6f34faSEddie James
442e6f34faSEddie James return chksum;
452e6f34faSEddie James }
462e6f34faSEddie James
ibm_panel_process_command(struct ibm_panel * panel)472e6f34faSEddie James static void ibm_panel_process_command(struct ibm_panel *panel)
482e6f34faSEddie James {
492e6f34faSEddie James u8 button;
502e6f34faSEddie James u8 chksum;
512e6f34faSEddie James
522e6f34faSEddie James if (panel->command[0] != 0xff && panel->command[1] != 0xf0) {
532e6f34faSEddie James dev_dbg(&panel->input->dev, "command invalid: %02x %02x\n",
542e6f34faSEddie James panel->command[0], panel->command[1]);
552e6f34faSEddie James return;
562e6f34faSEddie James }
572e6f34faSEddie James
582e6f34faSEddie James chksum = ibm_panel_calculate_checksum(panel);
592e6f34faSEddie James if (chksum != panel->command[sizeof(panel->command) - 1]) {
602e6f34faSEddie James dev_dbg(&panel->input->dev,
612e6f34faSEddie James "command failed checksum: %u != %u\n", chksum,
622e6f34faSEddie James panel->command[sizeof(panel->command) - 1]);
632e6f34faSEddie James return;
642e6f34faSEddie James }
652e6f34faSEddie James
662e6f34faSEddie James button = panel->command[2] & 0xf;
672e6f34faSEddie James if (button < PANEL_KEYCODES_COUNT) {
682e6f34faSEddie James input_report_key(panel->input, panel->keycodes[button],
692e6f34faSEddie James !(panel->command[2] & 0x80));
702e6f34faSEddie James input_sync(panel->input);
712e6f34faSEddie James } else {
722e6f34faSEddie James dev_dbg(&panel->input->dev, "unknown button %u\n",
732e6f34faSEddie James button);
742e6f34faSEddie James }
752e6f34faSEddie James }
762e6f34faSEddie James
ibm_panel_i2c_slave_cb(struct i2c_client * client,enum i2c_slave_event event,u8 * val)772e6f34faSEddie James static int ibm_panel_i2c_slave_cb(struct i2c_client *client,
782e6f34faSEddie James enum i2c_slave_event event, u8 *val)
792e6f34faSEddie James {
802e6f34faSEddie James unsigned long flags;
812e6f34faSEddie James struct ibm_panel *panel = i2c_get_clientdata(client);
822e6f34faSEddie James
832e6f34faSEddie James dev_dbg(&panel->input->dev, "event: %u data: %02x\n", event, *val);
842e6f34faSEddie James
852e6f34faSEddie James spin_lock_irqsave(&panel->lock, flags);
862e6f34faSEddie James
872e6f34faSEddie James switch (event) {
882e6f34faSEddie James case I2C_SLAVE_STOP:
892e6f34faSEddie James if (panel->idx == sizeof(panel->command))
902e6f34faSEddie James ibm_panel_process_command(panel);
912e6f34faSEddie James else
922e6f34faSEddie James dev_dbg(&panel->input->dev,
932e6f34faSEddie James "command incorrect size %u\n", panel->idx);
942e6f34faSEddie James fallthrough;
952e6f34faSEddie James case I2C_SLAVE_WRITE_REQUESTED:
962e6f34faSEddie James panel->idx = 0;
972e6f34faSEddie James break;
982e6f34faSEddie James case I2C_SLAVE_WRITE_RECEIVED:
992e6f34faSEddie James if (panel->idx < sizeof(panel->command))
1002e6f34faSEddie James panel->command[panel->idx++] = *val;
1012e6f34faSEddie James else
1022e6f34faSEddie James /*
1032e6f34faSEddie James * The command is too long and therefore invalid, so set the index
1042e6f34faSEddie James * to it's largest possible value. When a STOP is finally received,
1052e6f34faSEddie James * the command will be rejected upon processing.
1062e6f34faSEddie James */
1072e6f34faSEddie James panel->idx = U8_MAX;
1082e6f34faSEddie James break;
1092e6f34faSEddie James case I2C_SLAVE_READ_REQUESTED:
1102e6f34faSEddie James case I2C_SLAVE_READ_PROCESSED:
1112e6f34faSEddie James *val = 0xff;
1122e6f34faSEddie James break;
1132e6f34faSEddie James default:
1142e6f34faSEddie James break;
1152e6f34faSEddie James }
1162e6f34faSEddie James
1172e6f34faSEddie James spin_unlock_irqrestore(&panel->lock, flags);
1182e6f34faSEddie James
1192e6f34faSEddie James return 0;
1202e6f34faSEddie James }
1212e6f34faSEddie James
ibm_panel_probe(struct i2c_client * client)122b67df1e1SUwe Kleine-König static int ibm_panel_probe(struct i2c_client *client)
1232e6f34faSEddie James {
1242e6f34faSEddie James struct ibm_panel *panel;
1252e6f34faSEddie James int i;
1262e6f34faSEddie James int error;
1272e6f34faSEddie James
1282e6f34faSEddie James panel = devm_kzalloc(&client->dev, sizeof(*panel), GFP_KERNEL);
1292e6f34faSEddie James if (!panel)
1302e6f34faSEddie James return -ENOMEM;
1312e6f34faSEddie James
1322e6f34faSEddie James spin_lock_init(&panel->lock);
1332e6f34faSEddie James
1342e6f34faSEddie James panel->input = devm_input_allocate_device(&client->dev);
1352e6f34faSEddie James if (!panel->input)
1362e6f34faSEddie James return -ENOMEM;
1372e6f34faSEddie James
1382e6f34faSEddie James panel->input->name = client->name;
1392e6f34faSEddie James panel->input->id.bustype = BUS_I2C;
1402e6f34faSEddie James
1412e6f34faSEddie James error = device_property_read_u32_array(&client->dev,
1422e6f34faSEddie James "linux,keycodes",
1432e6f34faSEddie James panel->keycodes,
1442e6f34faSEddie James PANEL_KEYCODES_COUNT);
1452e6f34faSEddie James if (error) {
1462e6f34faSEddie James /*
1472e6f34faSEddie James * Use gamepad buttons as defaults for compatibility with
1482e6f34faSEddie James * existing applications.
1492e6f34faSEddie James */
1502e6f34faSEddie James panel->keycodes[0] = BTN_NORTH;
1512e6f34faSEddie James panel->keycodes[1] = BTN_SOUTH;
1522e6f34faSEddie James panel->keycodes[2] = BTN_SELECT;
1532e6f34faSEddie James }
1542e6f34faSEddie James
1552e6f34faSEddie James for (i = 0; i < PANEL_KEYCODES_COUNT; ++i)
1562e6f34faSEddie James input_set_capability(panel->input, EV_KEY, panel->keycodes[i]);
1572e6f34faSEddie James
1582e6f34faSEddie James error = input_register_device(panel->input);
1592e6f34faSEddie James if (error) {
1602e6f34faSEddie James dev_err(&client->dev,
1612e6f34faSEddie James "Failed to register input device: %d\n", error);
1622e6f34faSEddie James return error;
1632e6f34faSEddie James }
1642e6f34faSEddie James
1652e6f34faSEddie James i2c_set_clientdata(client, panel);
1662e6f34faSEddie James error = i2c_slave_register(client, ibm_panel_i2c_slave_cb);
1672e6f34faSEddie James if (error) {
1682e6f34faSEddie James dev_err(&client->dev,
1692e6f34faSEddie James "Failed to register as i2c slave: %d\n", error);
1702e6f34faSEddie James return error;
1712e6f34faSEddie James }
1722e6f34faSEddie James
1732e6f34faSEddie James return 0;
1742e6f34faSEddie James }
1752e6f34faSEddie James
ibm_panel_remove(struct i2c_client * client)1762e6f34faSEddie James static void ibm_panel_remove(struct i2c_client *client)
1772e6f34faSEddie James {
1782e6f34faSEddie James i2c_slave_unregister(client);
1792e6f34faSEddie James }
1802e6f34faSEddie James
1812e6f34faSEddie James static const struct of_device_id ibm_panel_match[] = {
1822e6f34faSEddie James { .compatible = "ibm,op-panel" },
1832e6f34faSEddie James { }
1842e6f34faSEddie James };
18525d0bef5SZeng Heng MODULE_DEVICE_TABLE(of, ibm_panel_match);
1862e6f34faSEddie James
1872e6f34faSEddie James static struct i2c_driver ibm_panel_driver = {
1882e6f34faSEddie James .driver = {
1892e6f34faSEddie James .name = DEVICE_NAME,
1902e6f34faSEddie James .of_match_table = ibm_panel_match,
1912e6f34faSEddie James },
192*d8bde56dSUwe Kleine-König .probe = ibm_panel_probe,
1932e6f34faSEddie James .remove = ibm_panel_remove,
1942e6f34faSEddie James };
1952e6f34faSEddie James module_i2c_driver(ibm_panel_driver);
1962e6f34faSEddie James
1972e6f34faSEddie James MODULE_AUTHOR("Eddie James <eajames@linux.ibm.com>");
1982e6f34faSEddie James MODULE_DESCRIPTION("IBM Operation Panel Driver");
1992e6f34faSEddie James MODULE_LICENSE("GPL");
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