input: add some initial keyboard matrix library stubs

drivers/input/CMakeLists.txt

@@ -9,6 +9,7 @@ zephyr_library_sources_ifdef(CONFIG_INPUT_FT5336 input_ft5336.c)
 zephyr_library_sources_ifdef(CONFIG_INPUT_GPIO_KEYS input_gpio_keys.c)
 zephyr_library_sources_ifdef(CONFIG_INPUT_GPIO_QDEC input_gpio_qdec.c)
 zephyr_library_sources_ifdef(CONFIG_INPUT_GT911 input_gt911.c)
+zephyr_library_sources_ifdef(CONFIG_INPUT_KBD_MATRIX input_kbd_matrix.c)
 zephyr_library_sources_ifdef(CONFIG_INPUT_NPCX_KBD input_npcx_kbd.c)
 zephyr_library_sources_ifdef(CONFIG_INPUT_STMPE811 input_stmpe811.c)
 zephyr_library_sources_ifdef(CONFIG_INPUT_XPT2046 input_xpt2046.c)

drivers/input/Kconfig

@@ -11,6 +11,7 @@ source "drivers/input/Kconfig.ft5336"
 source "drivers/input/Kconfig.gpio_keys"
 source "drivers/input/Kconfig.gpio_qdec"
 source "drivers/input/Kconfig.gt911"
+source "drivers/input/Kconfig.kbd_matrix"
 source "drivers/input/Kconfig.npcx"
 source "drivers/input/Kconfig.sdl"
 source "drivers/input/Kconfig.stmpe811"

drivers/input/Kconfig.kbd_matrix

@@ -0,0 +1,17 @@
+# Copyright 2023 Google LLC
+# SPDX-License-Identifier: Apache-2.0
+
+config INPUT_KBD_MATRIX
+	bool
+	help
+	  Enable library used for keyboard matrix drivers.
+
+if INPUT_KBD_MATRIX
+
+config INPUT_KBD_MATRIX_THREAD_STACK_SIZE
+	int "Stack size for the keyboard matrix thread"
+	default 1024
+	help
+	  Size of the stack used for the keyboard matrix thread.
+
+endif # INPUT_KBD_MATRIX

drivers/input/Kconfig.npcx

@@ -7,6 +7,7 @@ menuconfig INPUT_NPCX_KBD
 	bool "Nuvoton NPCX embedded controller (EC) keyboard scan driver"
 	default y
 	depends on DT_HAS_NUVOTON_NPCX_KBD_ENABLED
+	select INPUT_KBD_MATRIX
 	select MULTITHREADING
 	help
 	  This option enables the keyboard scan driver for NPCX family of
@@ -34,10 +35,4 @@ config INPUT_NPCX_KBD_POLL_COL_OUTPUT_SETTLE_TIME_US
 	  Delay (us) between setting column output and waiting for it
 	  to settle
 
-config INPUT_NPCX_KBD_THREAD_STACK_SIZE
-	int "Stack size for the kscan thread"
-	default 1024
-	help
-	  Size of the stack used for the kscan thread.
-
 endif # INPUT_NPCX_KBD

drivers/input/input_kbd_matrix.c

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2023 Google LLC
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/device.h>
+#include <zephyr/kernel.h>
+
+#include "input_kbd_matrix.h"
+
+int input_kbd_matrix_common_init(const struct device *dev)
+{
+	const struct input_kbd_matrix_common_config *cfg = dev->config;
+	const struct input_kbd_matrix_api *api = &cfg->api;
+	struct input_kbd_matrix_common_data *const data = dev->data;
+
+	k_thread_create(&data->thread, data->thread_stack,
+			CONFIG_INPUT_KBD_MATRIX_THREAD_STACK_SIZE,
+			api->polling_thread, (void *)dev, NULL, NULL,
+			K_PRIO_COOP(4), 0, K_NO_WAIT);
+
+	k_thread_name_set(&data->thread, dev->name);
+
+	return 0;
+}

drivers/input/input_kbd_matrix.h

@@ -0,0 +1,80 @@
+/*
+ * Copyright 2023 Google LLC
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/device.h>
+#include <zephyr/kernel.h>
+#include <zephyr/toolchain.h>
+
+/**
+ * @brief Keyboard matrix internal APIs.
+ */
+struct input_kbd_matrix_api {
+	k_thread_entry_t polling_thread;
+};
+
+/**
+ * @brief Common keyboard matrix config.
+ *
+ * This structure **must** be placed first in the driver's config structure.
+ */
+struct input_kbd_matrix_common_config {
+	struct input_kbd_matrix_api api;
+};
+
+/**
+ * @brief Initialize common keyboard matrix config from devicetree.
+ *
+ * @param api Pointer to a :c:struct:`input_kbd_matrix_api` structure.
+ */
+#define INPUT_KBD_MATRIX_DT_COMMON_CONFIG_INIT(node_id, _api) \
+	{ \
+		.api = _api, \
+	}
+
+/**
+ * @brief Initialize common keyboard matrix config from devicetree instance.
+ *
+ * @param inst Instance.
+ * @param api Pointer to a :c:struct:`input_kbd_matrix_api` structure.
+ */
+#define INPUT_KBD_MATRIX_DT_INST_COMMON_CONFIG_INIT(inst, api) \
+	INPUT_KBD_MATRIX_DT_COMMON_CONFIG_INIT(DT_DRV_INST(inst), api)
+
+/**
+ * @brief Common keyboard matrix data.
+ *
+ * This structure **must** be placed first in the driver's data structure.
+ */
+struct input_kbd_matrix_common_data {
+	struct k_thread thread;
+
+	K_KERNEL_STACK_MEMBER(thread_stack,
+			      CONFIG_INPUT_KBD_MATRIX_THREAD_STACK_SIZE);
+};
+
+/**
+ * @brief Validate the offset of the common data structures.
+ *
+ * @param config Name of the config structure.
+ * @param data Name of the data structure.
+ */
+#define INPUT_KBD_STRUCT_CHECK(config, data) \
+	BUILD_ASSERT(offsetof(config, common) == 0, \
+		     "struct input_kbd_matrix_common_config must be placed first"); \
+	BUILD_ASSERT(offsetof(data, common) == 0, \
+		     "struct input_kbd_matrix_common_data must be placed first")
+
+/**
+ * @brief Common function to initialize a keyboard matrix device at init time.
+ *
+ * This function must be called at the end of the device init function.
+ *
+ * @param dev Keyboard matrix device instance.
+ *
+ * @retval 0 If initialized successfully.
+ * @retval -errno Negative errno in case of failure.
+ */
+int input_kbd_matrix_common_init(const struct device *dev);

drivers/input/input_npcx_kbd.c

@@ -8,6 +8,7 @@
 #define DT_DRV_COMPAT nuvoton_npcx_kbd
 
 #include "soc_miwu.h"
+#include "input_kbd_matrix.h"
 
 #include <zephyr/drivers/clock_control.h>
 #include <zephyr/drivers/pinctrl.h>
@@ -32,6 +33,7 @@ LOG_MODULE_REGISTER(input_npcx_kbd);
 
 /* Driver config */
 struct input_npcx_kbd_config {
+	struct input_kbd_matrix_common_config common;
 	/* Keyboard scan controller base address */
 	struct kbs_reg *base;
 	/* Clock configuration */
@@ -51,6 +53,7 @@ struct input_npcx_kbd_config {
 };
 
 struct input_npcx_kbd_data {
+	struct input_kbd_matrix_common_data common;
 	int64_t poll_timeout_us;
 	uint32_t poll_period_us;
 	uint8_t matrix_stable_state[KSCAN_COL_SIZE];
@@ -66,11 +69,10 @@ struct input_npcx_kbd_data {
 	uint8_t scan_clk_cycle[SCAN_OCURRENCES];
 	struct k_sem poll_lock;
 	uint8_t scan_cycles_idx;
-	struct k_thread thread;
-
-	K_KERNEL_STACK_MEMBER(thread_stack, CONFIG_INPUT_NPCX_KBD_THREAD_STACK_SIZE);
 };
 
+INPUT_KBD_STRUCT_CHECK(struct input_npcx_kbd_config, struct input_npcx_kbd_data);
+
 /* Keyboard scan local functions */
 static void input_npcx_kbd_ksi_isr(const struct device *dev, struct npcx_wui *wui)
 {
@@ -474,19 +476,17 @@ static int input_npcx_kbd_init(const struct device *dev)
 	data->poll_period_us = (uint32_t)(CONFIG_INPUT_NPCX_KBD_POLL_PERIOD_MS * USEC_PER_MSEC);
 	data->poll_timeout_us = 100 * USEC_PER_MSEC;
 
-	k_thread_create(&data->thread, data->thread_stack,
-			CONFIG_INPUT_NPCX_KBD_THREAD_STACK_SIZE,
-			kbd_matrix_polling_thread, (void *)dev, NULL, NULL,
-			K_PRIO_COOP(4), 0, K_NO_WAIT);
-
-	k_thread_name_set(&data->thread, "npcx-kbd");
-
-	return 0;
+	return input_kbd_matrix_common_init(dev);
 }
 
 PINCTRL_DT_INST_DEFINE(0);
 
+static const struct input_kbd_matrix_api npcx_kbd_api = {
+	.polling_thread = kbd_matrix_polling_thread,
+};
+
 static const struct input_npcx_kbd_config npcx_kbd_cfg = {
+	.common = INPUT_KBD_MATRIX_DT_INST_COMMON_CONFIG_INIT(0, npcx_kbd_api),
 	.base = (struct kbs_reg *)DT_INST_REG_ADDR(0),
 	.pcfg = PINCTRL_DT_INST_DEV_CONFIG_GET(0),
 	.clk_cfg = NPCX_DT_CLK_CFG_ITEM(0),

dts/bindings/input/kbd-matrix-common.yaml

@@ -0,0 +1,6 @@
+# Copyright 2023 Google LLC
+# SPDX-License-Identifier: Apache-2.0
+
+description: Keyboard matrix device
+
+include: base.yaml

dts/bindings/input/nuvoton,npcx-kbd.yaml

@@ -5,7 +5,7 @@ description: Nuvoton NPCX keyboard scan controller
 
 compatible: "nuvoton,npcx-kbd"
 
-include: [base.yaml, pinctrl-device.yaml]
+include: [kbd-matrix-common.yaml, pinctrl-device.yaml]
 
 properties:
   reg: