--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for I2C connected Hynitron CST816x Series Touchscreen
+ *
+ * Copyright (C) 2025 Oleh Kuzhylnyi <kuzhylol@gmail.com>
+ */
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/unaligned.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+
+#define CST816X_RD_REG 0x01
+#define CST816X_NUM_KEYS 5
+
+struct cst816x_touch {
+ u8 gest;
+ u8 active;
+ u16 abs_x;
+ u16 abs_y;
+} __packed;
+
+struct cst816x_priv {
+ struct i2c_client *client;
+ struct gpio_desc *reset;
+ struct input_dev *input;
+ unsigned int keycode[CST816X_NUM_KEYS];
+ unsigned int keycodemax;
+};
+
+static int cst816x_parse_keycodes(struct device *dev, struct cst816x_priv *priv)
+{
+ int count;
+ int error;
+
+ if (device_property_present(dev, "linux,keycodes")) {
+ count = device_property_count_u32(dev, "linux,keycodes");
+ if (count < 0) {
+ error = count;
+ dev_err(dev, "failed to count keys: %d\n", error);
+ return error;
+ } else if (count > ARRAY_SIZE(priv->keycode)) {
+ dev_err(dev, "too many keys defined: %d\n", count);
+ return -EINVAL;
+ }
+ priv->keycodemax = count;
+
+ error = device_property_read_u32_array(dev, "linux,keycodes",
+ priv->keycode,
+ priv->keycodemax);
+ if (error) {
+ dev_err(dev, "failed to read keycodes: %d\n", error);
+ return error;
+ }
+ }
+
+ return 0;
+}
+
+static int cst816x_i2c_read_register(struct cst816x_priv *priv, u8 reg,
+ void *buf, size_t len)
+{
+ struct i2c_msg xfer[] = {
+ {
+ .addr = priv->client->addr,
+ .flags = 0,
+ .buf = ®,
+ .len = sizeof(reg),
+ },
+ {
+ .addr = priv->client->addr,
+ .flags = I2C_M_RD,
+ .buf = buf,
+ .len = len,
+ },
+ };
+ int error;
+ int ret;
+
+ ret = i2c_transfer(priv->client->adapter, xfer, ARRAY_SIZE(xfer));
+ if (ret != ARRAY_SIZE(xfer)) {
+ error = ret < 0 ? ret : -EIO;
+ dev_err(&priv->client->dev, "i2c rx err: %d\n", error);
+ return error;
+ }
+
+ return 0;
+}
+
+static u8 cst816x_gest_idx(u8 gest)
+{
+ u8 index;
+
+ switch (gest) {
+ case 0x01: /* Slide up gesture */
+ case 0x02: /* Slide down gesture */
+ case 0x03: /* Slide left gesture */
+ case 0x04: /* Slide right gesture */
+ index = gest;
+ break;
+ case 0x0c: /* Long press gesture */
+ default:
+ index = CST816X_NUM_KEYS;
+ break;
+ }
+
+ return index - 1;
+}
+
+static bool cst816x_process_touch(struct cst816x_priv *priv,
+ struct cst816x_touch *tch)
+{
+ if (cst816x_i2c_read_register(priv, CST816X_RD_REG, tch, sizeof(*tch)))
+ return false;
+
+ tch->abs_x = get_unaligned_be16(&tch->abs_x) & GENMASK(11, 0);
+ tch->abs_y = get_unaligned_be16(&tch->abs_y) & GENMASK(11, 0);
+
+ dev_dbg(&priv->client->dev, "x: %u, y: %u, t: %u, g: 0x%x\n",
+ tch->abs_x, tch->abs_y, tch->active, tch->gest);
+
+ return true;
+}
+
+static int cst816x_register_input(struct cst816x_priv *priv)
+{
+ priv->input = devm_input_allocate_device(&priv->client->dev);
+ if (!priv->input)
+ return -ENOMEM;
+
+ priv->input->name = "Hynitron CST816x Series Touchscreen";
+ priv->input->phys = "input/ts";
+ priv->input->id.bustype = BUS_I2C;
+
+ input_set_drvdata(priv->input, priv);
+
+ input_set_abs_params(priv->input, ABS_X, 0, 240, 0, 0);
+ input_set_abs_params(priv->input, ABS_Y, 0, 240, 0, 0);
+ input_set_capability(priv->input, EV_KEY, BTN_TOUCH);
+
+ priv->input->keycode = priv->keycode;
+ priv->input->keycodesize = sizeof(priv->keycode[0]);
+ priv->input->keycodemax = priv->keycodemax;
+
+ for (int i = 0; i < priv->keycodemax; i++) {
+ if (priv->keycode[i] == KEY_RESERVED)
+ continue;
+
+ input_set_capability(priv->input, EV_KEY, priv->keycode[i]);
+ }
+
+ return input_register_device(priv->input);
+}
+
+static void cst816x_reset(struct cst816x_priv *priv)
+{
+ gpiod_set_value_cansleep(priv->reset, 1);
+ msleep(50);
+ gpiod_set_value_cansleep(priv->reset, 0);
+ msleep(100);
+}
+
+static irqreturn_t cst816x_irq_cb(int irq, void *cookie)
+{
+ struct cst816x_priv *priv = cookie;
+ struct cst816x_touch tch;
+
+ if (!cst816x_process_touch(priv, &tch))
+ return IRQ_HANDLED;
+
+ input_report_abs(priv->input, ABS_X, tch.abs_x);
+ input_report_abs(priv->input, ABS_Y, tch.abs_y);
+
+ if (tch.gest)
+ input_report_key(priv->input,
+ priv->keycode[cst816x_gest_idx(tch.gest)],
+ tch.active);
+
+ input_report_key(priv->input, BTN_TOUCH, tch.active);
+
+ input_sync(priv->input);
+
+ return IRQ_HANDLED;
+}
+
+static int cst816x_probe(struct i2c_client *client)
+{
+ struct device *dev = &client->dev;
+ struct cst816x_priv *priv;
+ int error;
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->client = client;
+
+ priv->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+ if (IS_ERR(priv->reset))
+ return dev_err_probe(dev, PTR_ERR(priv->reset),
+ "gpio reset request failed\n");
+
+ if (priv->reset)
+ cst816x_reset(priv);
+
+ error = cst816x_parse_keycodes(dev, priv);
+ if (error)
+ dev_warn(dev, "no gestures found in dt\n");
+
+ error = cst816x_register_input(priv);
+ if (error)
+ return dev_err_probe(dev, error, "input register failed\n");
+
+ error = devm_request_threaded_irq(dev, client->irq,
+ NULL, cst816x_irq_cb, IRQF_ONESHOT,
+ dev_driver_string(dev), priv);
+ if (error)
+ return dev_err_probe(dev, error, "irq request failed\n");
+
+ return 0;
+}
+
+static const struct i2c_device_id cst816x_id[] = {
+ { .name = "cst816s", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, cst816x_id);
+
+static const struct of_device_id cst816x_of_match[] = {
+ { .compatible = "hynitron,cst816s", },
+ { }
+};
+MODULE_DEVICE_TABLE(of, cst816x_of_match);
+
+static struct i2c_driver cst816x_driver = {
+ .driver = {
+ .name = "cst816x",
+ .of_match_table = cst816x_of_match,
+ },
+ .id_table = cst816x_id,
+ .probe = cst816x_probe,
+};
+
+module_i2c_driver(cst816x_driver);
+
+MODULE_AUTHOR("Oleh Kuzhylnyi <kuzhylol@gmail.com>");
+MODULE_DESCRIPTION("Hynitron CST816x Series Touchscreen Driver");
+MODULE_LICENSE("GPL");
projects / users / jedix / linux-maple.git / commitdiff