gistfile1.txt

// SPDX-License-Identifier: GPL-2.0
#include <linux/init.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/delay.h>

static void nunchuk_read_regs(struct i2c_client *client,
			      u8 *buf)
{
	char zero = 0;
	int ret;

	msleep(10);

	ret = i2c_master_send(client, &zero, sizeof(zero));
	if (ret != sizeof(zero))
		return;

	msleep(10);

	ret = i2c_master_recv(client, buf, 6);
	if (ret != 6)
		return;
}

static int nunchuk_probe(struct i2c_client *client,
			 const struct i2c_device_id *id)
{
	char buf1[] = { 0xf0, 0x55 };
	char buf2[] = { 0xfb, 0x00 };
	char regs[6];
	int ret, zpressed, cpressed;

	pr_info("Coucou from %s\n", __func__);

	ret = i2c_master_send(client, buf1, sizeof(buf1));
	if (ret != sizeof(buf1))
		return -ENODEV;

	udelay(1000);

	ret = i2c_master_send(client, buf2, sizeof(buf2));
	if (ret != sizeof(buf2))
		return -ENODEV;

	/* dummy read */
	nunchuk_read_regs(client, regs);

	nunchuk_read_regs(client, regs);

	zpressed = regs[5] & BIT(0) ? 0 : 1;
	cpressed = regs[5] & BIT(1) ? 0 : 1;

	pr_info("zpressed: %s, cpressed = %s\n",
		zpressed ? "YES" : "NO",
		cpressed ? "YES" : "NO");

	return 0;
}

static int nunchuk_remove(struct i2c_client *client)
{
	pr_info("Coucou from %s\n", __func__);
	return 0;
}

static const struct of_device_id nunchuk_of_ids[] = {
	{ .compatible = "nintendo,nunchuk" },
	{ /* sentinel */ },
};

static struct i2c_driver nunchuk_driver = {
	.probe = nunchuk_probe,
	.remove = nunchuk_remove,
	.driver = {
		.name = "nunchuk",
		.of_match_table = nunchuk_of_ids,
	},
};

module_i2c_driver(nunchuk_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Thomas Petazzoni");
MODULE_DESCRIPTION("Nunchuk driver");