feat(sensor): Add Pimoroni PIM447 trackball driver.

app/drivers/sensor/CMakeLists.txt

@@ -2,4 +2,5 @@
 # SPDX-License-Identifier: MIT
 
 add_subdirectory_ifdef(CONFIG_ZMK_BATTERY battery)
-add_subdirectory_ifdef(CONFIG_EC11 ec11)
+add_subdirectory_ifdef(CONFIG_EC11 ec11)
+add_subdirectory_ifdef(CONFIG_ZMK_TRACKBALL_PIM447 trackball_pim447)

app/drivers/sensor/Kconfig

@@ -2,4 +2,5 @@
 # SPDX-License-Identifier: MIT
 
 rsource "battery/Kconfig"
-rsource "ec11/Kconfig"
+rsource "ec11/Kconfig"
+rsource "trackball_pim447/Kconfig"

app/drivers/sensor/trackball_pim447/CMakeLists.txt

@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()
+zephyr_library_sources(trackball_pim447.c)

app/drivers/sensor/trackball_pim447/Kconfig

@@ -0,0 +1,8 @@
+# Copyright (c) 2021 The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+config ZMK_TRACKBALL_PIM447
+	bool "ZMK PIM447 trackball"
+	depends on I2C
+	help
+	  Enable I2C-based driver for Pimoroni PIM447 trackball.

app/drivers/sensor/trackball_pim447/trackball_pim447.c

@@ -0,0 +1,167 @@
+/*
+ * Copyright (c) 2021 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#define DT_DRV_COMPAT pimoroni_trackball_pim447
+
+#include <drivers/i2c.h>
+#include <drivers/sensor.h>
+
+#define LOG_LEVEL CONFIG_SENSOR_LOG_LEVEL
+#include <logging/log.h>
+LOG_MODULE_REGISTER(trackball_pim447);
+
+#define TRACKBALL_PIM447_REG_LEFT   0x04
+#define TRACKBALL_PIM447_REG_RIGHT  0x05
+#define TRACKBALL_PIM447_REG_UP     0x06
+#define TRACKBALL_PIM447_REG_DOWN   0x07
+#define TRACKBALL_PIM447_REG_SWITCH 0x08
+
+#define TRACKBALL_PIM447_REG_MIN    TRACKBALL_PIM447_REG_LEFT
+#define TRACKBALL_PIM447_REG_MAX    TRACKBALL_PIM447_REG_SWITCH
+
+struct trackball_pim447_data {
+    const struct device *i2c_dev;
+    int32_t dx;
+    int32_t dy;
+    int32_t dz;
+};
+
+static int trackball_pim447_read_reg(const struct device *dev,
+                                     uint8_t reg, uint8_t *value)
+{
+    struct trackball_pim447_data *data = dev->data;
+
+    if (reg < TRACKBALL_PIM447_REG_MIN || reg > TRACKBALL_PIM447_REG_MAX) {
+        return -ENOTSUP;
+    }
+
+    int status = i2c_reg_read_byte(data->i2c_dev, DT_INST_REG_ADDR(0),
+                                   reg, value);
+    if (status < 0) {
+        LOG_ERR("Sensor reg read byte failed");
+        return status;
+    }
+
+    return 0;
+}
+
+static int trackball_pim447_read_axis(const struct device *dev,
+                                      uint8_t reg_negative,
+                                      uint8_t reg_positive,
+                                      int32_t *value)
+{
+    uint8_t value_negative;
+    uint8_t value_positive;
+    int status;
+
+    status = trackball_pim447_read_reg(dev, reg_negative, &value_negative);
+    if (status < 0) {
+        return status;
+    }
+
+    status = trackball_pim447_read_reg(dev, reg_positive, &value_positive);
+    if (status < 0) {
+        return status;
+    }
+
+    *value = value_positive - value_negative;
+
+    return 0;
+}
+
+static int trackball_pim447_sample_fetch(const struct device *dev,
+                                         enum sensor_channel chan)
+{
+    struct trackball_pim447_data *data = dev->data;
+    int status;
+
+    if (chan == SENSOR_CHAN_ALL || chan == SENSOR_CHAN_POS_DX) {
+        status = trackball_pim447_read_axis(dev,
+                                            TRACKBALL_PIM447_REG_LEFT,
+                                            TRACKBALL_PIM447_REG_RIGHT,
+                                            &data->dx);
+        if (status < 0) {
+            return status;
+        }
+    }
+
+    if (chan == SENSOR_CHAN_ALL || chan == SENSOR_CHAN_POS_DY) {
+        status = trackball_pim447_read_axis(dev,
+                                            TRACKBALL_PIM447_REG_UP,
+                                            TRACKBALL_PIM447_REG_DOWN,
+                                            &data->dy);
+        if (status < 0) {
+            return status;
+        }
+    }
+
+    if (chan == SENSOR_CHAN_ALL || chan == SENSOR_CHAN_POS_DZ) {
+        uint8_t value;
+        status = trackball_pim447_read_reg(dev,
+                                           TRACKBALL_PIM447_REG_SWITCH,
+                                           &value);
+        if (status < 0) {
+            return status;
+        }
+
+        data->dz = value;
+    }
+
+    return 0;
+}
+
+static int trackball_pim447_channel_get(const struct device *dev,
+                                        enum sensor_channel chan,
+                                        struct sensor_value *val)
+{
+    struct trackball_pim447_data *data = dev->data;
+
+    /* Not used.  */
+    val->val2 = 0;
+
+    switch (chan) {
+    case SENSOR_CHAN_POS_DX:
+        val->val1 = data->dx;
+        break;
+
+    case SENSOR_CHAN_POS_DY:
+        val->val1 = data->dy;
+        break;
+
+    case SENSOR_CHAN_POS_DZ:
+        val->val1 = data->dz;
+        break;
+
+    default:
+        return -ENOTSUP;
+    }
+
+    return 0;
+}
+
+static int trackball_pim447_init(const struct device *dev)
+{
+    struct trackball_pim447_data *data = dev->data;
+
+    data->i2c_dev = device_get_binding(DT_INST_BUS_LABEL(0));
+    if (data->i2c_dev == NULL) {
+        LOG_ERR("Failed to get I2C device");
+        return -EINVAL;
+    }
+
+    return 0;
+}
+
+static struct trackball_pim447_data trackball_pim447_data;
+
+static const struct sensor_driver_api trackball_pim447_api = {
+    .sample_fetch = trackball_pim447_sample_fetch,
+    .channel_get  = trackball_pim447_channel_get,
+};
+
+DEVICE_DT_INST_DEFINE(0, &trackball_pim447_init, device_pm_control_nop,
+                      &trackball_pim447_data, NULL, POST_KERNEL,
+                      CONFIG_SENSOR_INIT_PRIORITY, &trackball_pim447_api);