drivers: display: Added LPM013M126 display driver.

Add support for JDI LPM013M126 RGB memory display

Co-developed-by: Elgin Perumbilly <[email protected]>
Signed-off-by: Elgin Perumbilly <[email protected]>
Signed-off-by: Bhavin Sharma <[email protected]>

Author: S-Bhavin

drivers/display/CMakeLists.txt

@@ -41,6 +41,7 @@ zephyr_library_sources_ifdef(CONFIG_NT35510		display_nt35510.c)
 zephyr_library_sources_ifdef(CONFIG_RENESAS_RA_GLCDC		display_renesas_ra.c)
 zephyr_library_sources_ifdef(CONFIG_ILI9806E_DSI		display_ili9806e_dsi.c)
 zephyr_library_sources_ifdef(CONFIG_ST7701 display_st7701.c)
+zephyr_library_sources_ifdef(CONFIG_LPM013M126 display_lpm013m126.c)
 
 zephyr_library_sources_ifdef(CONFIG_MICROBIT_DISPLAY
 	mb_display.c

drivers/display/Kconfig

@@ -58,5 +58,6 @@ source "drivers/display/Kconfig.nt35510"
 source "drivers/display/Kconfig.renesas_ra"
 source "drivers/display/Kconfig.ili9806e_dsi"
 source "drivers/display/Kconfig.st7701"
+source "drivers/display/Kconfig.lpm013m126"
 
 endif # DISPLAY

drivers/display/Kconfig.lpm013m126

@@ -0,0 +1,10 @@
+# Copyright (c) 2025 Silicon Signals Pvt. Ltd.
+# SPDX-License-Identifier: Apache-2.0
+
+config LPM013M126
+	bool "LPM013M126 memory display controller driver"
+	default y
+	depends on DT_HAS_JDI_LPM013M126_ENABLED
+	select SPI
+	help
+		Enable driver for JDI memory display series LPM013M126

drivers/display/display_lpm013m126.c

@@ -0,0 +1,269 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Copyright (c) 2025 Silicon Signals Pvt. Ltd.
+ * Author: Bhavin Sharma <[email protected]>
+ * Author: Elgin Perumbilly <[email protected]>
+ */
+
+#define DT_DRV_COMPAT jdi_lpm013m126
+
+#include <zephyr/logging/log.h>
+LOG_MODULE_REGISTER(lpm013m126, CONFIG_DISPLAY_LOG_LEVEL);
+
+#include <string.h>
+#include <zephyr/device.h>
+#include <zephyr/drivers/display.h>
+#include <zephyr/init.h>
+#include <zephyr/drivers/gpio.h>
+#include <zephyr/drivers/spi.h>
+#include <zephyr/kernel.h>
+
+/* Panel properties */
+#define LPM_BPP         3
+
+/* Command bytes */
+#define LPM_WRITELINE_CMD   0x80
+#define LPM_ALLCLEAR_CMD    0x20
+
+struct lpm013m126_data {
+	struct k_timer vcom_timer;
+	int vcom_state;
+};
+
+struct lpm013m126_config {
+	struct spi_dt_spec bus;
+	struct gpio_dt_spec disp_gpio;
+	struct gpio_dt_spec extcomin_gpio;
+	uint32_t extcomin_freq;
+	uint8_t width;
+	uint8_t height;
+};
+
+/* bit-reversal of row address */
+static inline uint8_t bitrev8(uint8_t x)
+{
+	x = ((x & 0xF0) >> 4) | ((x & 0x0F) << 4);
+	x = ((x & 0xCC) >> 2) | ((x & 0x33) << 2);
+	x = ((x & 0xAA) >> 1) | ((x & 0x55) << 1);
+	return x;
+}
+
+/* The native format (1 bit per channel) is rather unusual. LVGL and
+ * other libraries don't support it. In addition, the format is not
+ * very convenient for the application. So, we prefer to advertise
+ * a well known format and convert it under the hood.
+ * A native implementation of this format would allow to save memory
+ * for the frame buffer (11kB instead of 30kB).
+ */
+static inline uint8_t rgb565_to_rgb3(uint16_t color)
+{
+	uint8_t r = FIELD_GET(0xF800, color);
+	uint8_t g = FIELD_GET(0x07E0, color);
+	uint8_t b = FIELD_GET(0x001F, color);
+
+	r >>= 4;
+	g >>= 5;
+	b >>= 4;
+	return (r << 2) | (g << 1) | b;
+}
+
+/* Pack one row of RGB565 pixels into panel format */
+static void lpm_pack_row(const struct device *dev, uint8_t *dst, const uint16_t *src)
+{
+	const struct lpm013m126_config *cfg = dev->config;
+
+	int bitpos = 0;
+	uint8_t byte = 0;
+
+	for (int x = 0; x < cfg->width; x++) {
+		uint8_t pix = rgb565_to_rgb3(src[x]);
+
+		for (int b = 2; b >= 0; b--) {
+			byte |= ((pix >> b) & 0x1) << (7 - bitpos);
+			bitpos++;
+
+			if (bitpos == 8) {
+				*dst++ = byte;
+				bitpos = 0;
+				byte = 0;
+			}
+		}
+	}
+	/* flush final partial byte if needed */
+	if (bitpos) {
+		*dst++ = byte;
+	}
+}
+
+/* VCOM toggle callback */
+static void lpm_vcom_toggle(struct k_timer *timer)
+{
+	const struct device *dev = k_timer_user_data_get(timer);
+	const struct lpm013m126_config *cfg = dev->config;
+	struct lpm013m126_data *data = dev->data;
+
+	data->vcom_state = !data->vcom_state;
+	gpio_pin_set_dt(&cfg->extcomin_gpio, data->vcom_state);
+}
+
+/* Send a line to the display */
+static int lpm_send_line(const struct device *dev, uint8_t line, uint8_t *buf, size_t len)
+{
+	const struct lpm013m126_config *cfg = dev->config;
+
+	uint8_t cmd = LPM_WRITELINE_CMD;
+	uint8_t addr = bitrev8(line);
+
+	struct spi_buf tx_bufs[] = {
+		{ .buf = &cmd,  .len = 1 },
+		{ .buf = &addr, .len = 1 },
+		{ .buf = buf, .len = len },
+	};
+
+	struct spi_buf_set tx = {
+		.buffers = tx_bufs,
+		.count = ARRAY_SIZE(tx_bufs)
+	};
+
+	return spi_write_dt(&cfg->bus, &tx);
+}
+
+/* Send all-clear command */
+static int lpm_all_clear(const struct device *dev)
+{
+	const struct lpm013m126_config *cfg = dev->config;
+
+	uint8_t cmd = LPM_ALLCLEAR_CMD;
+	uint8_t dummy = 0x00;
+
+	struct spi_buf tx_bufs[] = {
+		{ .buf = &cmd, .len = 1 },
+		{ .buf = &dummy, .len = 1 },
+	};
+
+	struct spi_buf_set tx = {
+		.buffers = tx_bufs,
+		.count = ARRAY_SIZE(tx_bufs)
+	};
+
+	return spi_write_dt(&cfg->bus, &tx);
+}
+
+/* Write buffer to panel */
+static int lpm_write(const struct device *dev, const uint16_t x, const uint16_t y,
+		     const struct display_buffer_descriptor *desc, const void *buf)
+{
+	const struct lpm013m126_config *cfg = dev->config;
+
+	if (x != 0 || desc->width != cfg->width) {
+		LOG_ERR("Only full-width writes supported");
+		return -ENOTSUP;
+	}
+	if ((y + desc->height) > cfg->height) {
+		LOG_ERR("Buffer out of bounds");
+		return -EINVAL;
+	}
+
+	const uint16_t *src = buf;
+	size_t packed_len = DIV_ROUND_UP(cfg->width * LPM_BPP, 8);
+	uint8_t linebuf[packed_len];
+
+	for (int row = 0; row < desc->height; row++) {
+		lpm_pack_row(dev, linebuf, src);
+		lpm_send_line(dev, y + row + 1, linebuf, packed_len);
+		src += cfg->width;
+	}
+
+	return 0;
+}
+
+static void lpm_get_capabilities(const struct device *dev, struct display_capabilities *caps)
+{
+	const struct lpm013m126_config *cfg = dev->config;
+
+	memset(caps, 0, sizeof(*caps));
+	caps->x_resolution = cfg->width;
+	caps->y_resolution = cfg->height;
+	caps->supported_pixel_formats = PIXEL_FORMAT_RGB_565;
+	caps->current_pixel_format = PIXEL_FORMAT_RGB_565;
+	caps->screen_info = SCREEN_INFO_X_ALIGNMENT_WIDTH;
+}
+
+static int lpm_set_pixel_format(const struct device *dev, enum display_pixel_format pf)
+{
+	return (pf == PIXEL_FORMAT_RGB_565) ? 0 : -ENOTSUP;
+}
+
+static int lpm_blanking_off(const struct device *dev)
+{
+	const struct lpm013m126_config *cfg = dev->config;
+
+	return gpio_pin_set_dt(&cfg->disp_gpio, 1);
+}
+
+static int lpm_blanking_on(const struct device *dev)
+{
+	const struct lpm013m126_config *cfg = dev->config;
+
+	return gpio_pin_set_dt(&cfg->disp_gpio, 0);
+}
+
+static int lpm_init(const struct device *dev)
+{
+	const struct lpm013m126_config *cfg = dev->config;
+
+	struct lpm013m126_data *data = dev->data;
+
+	if (!spi_is_ready_dt(&cfg->bus)) {
+		LOG_ERR("SPI not ready");
+		return -ENODEV;
+	}
+	if (!gpio_is_ready_dt(&cfg->disp_gpio)) {
+		LOG_ERR("DISP pin not ready");
+		return -ENODEV;
+	}
+	if (!gpio_is_ready_dt(&cfg->extcomin_gpio)) {
+		LOG_ERR("EXTCOMIN pin not ready");
+		return -ENODEV;
+	}
+
+	gpio_pin_configure_dt(&cfg->disp_gpio, GPIO_OUTPUT_HIGH);
+	gpio_pin_configure_dt(&cfg->extcomin_gpio, GPIO_OUTPUT_LOW);
+
+	lpm_all_clear(dev);
+
+	data->vcom_state = 0;
+	k_timer_init(&data->vcom_timer, lpm_vcom_toggle, NULL);
+	k_timer_user_data_set(&data->vcom_timer, (void *)dev);
+	k_timer_start(&data->vcom_timer, K_MSEC(1000 / cfg->extcomin_freq / 2),
+		      K_MSEC(1000 / cfg->extcomin_freq / 2));
+
+	return 0;
+}
+
+static const struct display_driver_api lpm_api = {
+	.blanking_on = lpm_blanking_on,
+	.blanking_off = lpm_blanking_off,
+	.write = lpm_write,
+	.get_capabilities = lpm_get_capabilities,
+	.set_pixel_format = lpm_set_pixel_format,
+};
+
+#define LPM013M126_INIT(inst)							\
+	static const struct lpm013m126_config lpm_cfg_##inst = {		\
+		.bus = SPI_DT_SPEC_INST_GET(inst, SPI_OP_MODE_MASTER |		\
+					    SPI_WORD_SET(8) |			\
+					    SPI_TRANSFER_MSB, 0),		\
+		.disp_gpio = GPIO_DT_SPEC_INST_GET(inst, disp_gpios),		\
+		.extcomin_gpio = GPIO_DT_SPEC_INST_GET(inst, extcomin_gpios),	\
+		.extcomin_freq = DT_INST_PROP(inst, extcomin_frequency),	\
+		.width = DT_INST_PROP(inst, width),				\
+		.height = DT_INST_PROP(inst, height),				\
+	};									\
+	static struct lpm013m126_data lpm_data_##inst;				\
+	DEVICE_DT_INST_DEFINE(inst, lpm_init, NULL, &lpm_data_##inst,		\
+			      &lpm_cfg_##inst, POST_KERNEL,			\
+			      CONFIG_DISPLAY_INIT_PRIORITY, &lpm_api);
+
+DT_INST_FOREACH_STATUS_OKAY(LPM013M126_INIT);

dts/bindings/display/jdi,lpm013m126.yaml

@@ -0,0 +1,29 @@
+# Copyright (c) 2025 Silicon Signals Pvt. Ltd.
+# SPDX-License-Identifier: Apache-2.0
+
+description: JDI LPM013M126 176x176 Color Memory LCD
+
+compatible: "jdi,lpm013m126"
+
+include: [spi-device.yaml, display-controller.yaml]
+
+properties:
+  disp-gpios:
+    type: phandle-array
+    description: |
+      DISPLAY enable pin.
+      Determines whether the LCD shows its memory content or a blank (white) screen.
+      When defined, this pin is driven high during initialization.
+      Blanking operations provided by the API can toggle this pin as needed.
+
+  extcomin-gpios:
+    type: phandle-array
+    description: |
+      EXTCOMIN pin
+      Provides a square wave on the EXTCOMIN pin to toggle VCOM (common electrode voltage)
+      level.
+
+  extcomin-frequency:
+    type: int
+    description: |
+      Frequency (Hz) to toggle the EXTCOMIN pin.