drivers/lcd: add MCU-driven low-level parallel interface

drivers/include/lcd.h

@@ -256,8 +256,8 @@ void lcd_ll_release(lcd_t *dev);
  *
  * @param[in]   dev     device descriptor
  * @param[in]   cmd     command code
- * @param[in]   data    command data to the device
- * @param[in]   len     length of the command data
+ * @param[in]   data    command data to the device or NULL for commands without data
+ * @param[in]   len     length of the command data or 0 for commands without data
  */
 void lcd_ll_write_cmd(lcd_t *dev, uint8_t cmd, const uint8_t *data,
                       size_t len);
@@ -279,6 +279,18 @@ void lcd_ll_write_cmd(lcd_t *dev, uint8_t cmd, const uint8_t *data,
  * @param[in]   len     length of the returned data
  */
 void lcd_ll_read_cmd(lcd_t *dev, uint8_t cmd, uint8_t *data, size_t len);
+
+/**
+ * @brief   Set the LCD work area
+ *
+ * @param[in] dev  Pointer to the selected driver
+ * @param[in] x1   x coordinate of the first corner
+ * @param[in] x2   x coordinate of the opposite corner
+ * @param[in] y1   y coordinate of the first corner
+ * @param[in] y2   y coordinate of the opposite corner
+ *
+ */
+void lcd_ll_set_area(lcd_t *dev, uint16_t x1, uint16_t x2, uint16_t y1, uint16_t y2);
 /** @} */
 
 /**
@@ -338,8 +350,8 @@ void lcd_pixmap(lcd_t *dev, uint16_t x1, uint16_t x2, uint16_t y1,
  *
  * @param[in]   dev     device descriptor
  * @param[in]   cmd     command code
- * @param[in]   data    command data to the device
- * @param[in]   len     length of the command data
+ * @param[in]   data    command data to the device or NULL for commands without data
+ * @param[in]   len     length of the command data or 0 for commands without data
  */
 void lcd_write_cmd(lcd_t *dev, uint8_t cmd, const uint8_t *data,
                    size_t len);
@@ -375,6 +387,109 @@ void lcd_invert_on(lcd_t *dev);
 void lcd_invert_off(lcd_t *dev);
 /** @} */
 
+#if MODULE_LCD_PARALLEL || DOXYGEN
+/**
+ * @name    Low-level MCU 8080 8-/16-bit parallel interface
+ *
+ * The low-level MCU 8080 8-/16-bit parallel interface (low-level parallel
+ * interface for short) is used when the LCD device is connected via a parallel
+ * interface. Either the GPIO-driven low-level parallel interface provided by
+ * this LCD driver or a low-level parallel interface implemented by the MCU,
+ * such as the STM32 FMC peripheral, can be used. If the MCU provides its
+ * own implementation of the low-level parallel interface, it can be used
+ * by implementing the following low-level parallel interface driver functions,
+ * enabling the `lcd_parallel_ll_mcu` module and defining the
+ * @ref lcd_ll_par_driver variable of type @ref lcd_ll_par_driver_t.
+ *
+ * @{
+ */
+
+/**
+ * @brief   Low-level MCU 8080 8-/16-bit parallel interface driver
+ *
+ * If the MCU-driven low-level parallel interface is enabled by
+ * module `lcd_ll_parallel_mcu`, the implementation of the MCU low-level
+ * parallel interface has to define a variable @ref lcd_ll_par_driver of this
+ * type. All or a set of members have to point to the low-level parallel
+ * interface functions implemented by the MCU. For functions that are not
+ * implemented by the MCU, the members have to be set to the corresponding
+ * GPIO-driven low-level parallel interface functions provided by the LCD
+ * driver.
+ */
+typedef struct {
+    /**
+     * @brief   Initialize the MCU-driven low-level parallel interface
+     *
+     * @param[in]   dev     device descriptor
+     */
+    void (*init)(lcd_t *dev);
+
+    /**
+     * @brief   Set the data direction of the low-level parallel interface
+     *
+     * @param[in]   dev     device descriptor
+     * @param[in]   output  set to output mode if true and to input mode otherwise
+     */
+    void (*set_data_dir)(lcd_t *dev, bool output);
+
+    /**
+     * @brief   Write command using the MCU-driven low-level parallel interface
+     *
+     * @param[in]   dev     device descriptor
+     * @param[in]   cmd     command
+     * @param[in]   cont    operation is continued
+     */
+    void (*cmd_start)(lcd_t *dev, uint8_t cmd, bool cont);
+
+    /**
+     * @brief   Write a byte using the MCU-driven low-level parallel interface
+     *
+     * @param[in]   dev     device descriptor
+     * @param[in]   cont    operation is continued
+     * @param[in]   out     byte to be written
+     */
+    void (*write_byte)(lcd_t *dev, bool cont, uint8_t out);
+
+    /**
+     * @brief   Read a byte using the MCU-driven low-level parallel interface
+     *
+     * @param[in]   dev     device descriptor
+     * @param[in]   cont    operation is continued
+     *
+     * @return  byte read
+     */
+    uint8_t (*read_byte)(lcd_t *dev, bool cont);
+
+#if MODULE_LCD_PARALLEL_16BIT || DOXYGEN
+    /**
+     * @brief   Write a word using the MCU-driven low-level parallel interface
+     *
+     * @param[in]   dev     device descriptor
+     * @param[in]   cont    operation is continued
+     * @param[in]   out     word to be written
+     */
+    void (*write_word)(lcd_t *dev, bool cont, uint16_t out);
+
+    /**
+     * @brief   Read a word using the MCU-driven low-level parallel interface
+     *
+     * @param[in]   dev     device descriptor
+     * @param[in]   cont    operation is continued
+     *
+     * @return  word read
+     */
+    uint16_t (*read_word)(lcd_t *dev, bool cont);
+#endif
+} lcd_ll_par_driver_t;
+
+/**
+ * @brief   Low-level parallel interface driver instance
+ */
+extern const lcd_ll_par_driver_t lcd_ll_par_driver;
+
+/** @} */
+#endif
+
 #ifdef __cplusplus
 }
 #endif

drivers/lcd/Kconfig

@@ -11,6 +11,8 @@ config MODULE_LCD
     depends on TEST_KCONFIG
     select MODULE_PERIPH_GPIO
 
+if MODULE_LCD
+
 config MODULE_LCD_MULTI_CNTRL
     bool
     help
@@ -21,25 +23,31 @@ config MODULE_LCD_SPI
     default y if !MODULE_LCD_PARALLEL && !MODULE_LCD_PARALLEL_16BIT
     default y if HAVE_LCD_SPI
     depends on HAS_PERIPH_SPI
-    depends on MODULE_LCD
     select MODULE_PERIPH_SPI
     help
         SPI serial interface is used
 
 config MODULE_LCD_PARALLEL
     bool
     default y if HAVE_LCD_PARALLEL || HAVE_LCD_PARALLEL_16BIT
-    depends on MODULE_LCD
     help
         MCU 8080 8-/16-bit parallel interface is used
 
 config MODULE_LCD_PARALLEL_16BIT
     bool
     default y if HAVE_LCD_PARALLEL_16BIT
-    depends on MODULE_LCD
     help
         MCU 8080 16-bit paralell interface is used
 
+config MODULE_LCD_PARALLEL_LL_MCU
+    bool
+    default y if HAVE_LCD_PARALLEL_LL_MCU
+    depends on MODULE_LCD_PARALLEL
+    help
+        MCU 8080 8-/16-bit low-level parallel interface is provided by the MCU.
+
+endif
+
 config HAVE_LCD_SPI
     bool
     help
@@ -58,6 +66,12 @@ config HAVE_LCD_PARALLEL_16BIT
         Indicates that a display with MCU 8080 16-bit parallel interface
         is present
 
+config HAVE_LCD_PARALLEL_LL_MCU
+    bool
+    help
+        Indicates that the MCU provides the MCU 8080 8-/16-bit low-level
+        parallel interface implementation.
+
 menuconfig KCONFIG_USEMODULE_LCD
     bool "Configure LCD driver"
     depends on USEMODULE_LCD

drivers/lcd/Makefile.dep

@@ -1,6 +1,6 @@
 FEATURES_REQUIRED += periph_gpio
 
-ifneq (,$(filter lcd_parallel_16bit,$(USEMODULE)))
+ifneq (,$(filter lcd_parallel_%,$(USEMODULE)))
   USEMODULE += lcd_parallel
 endif
 

drivers/lcd/Makefile.include

@@ -3,6 +3,7 @@ PSEUDOMODULES += lcd_multi_cntrl
 PSEUDOMODULES += lcd_spi
 PSEUDOMODULES += lcd_parallel
 PSEUDOMODULES += lcd_parallel_16bit
+PSEUDOMODULES += lcd_parallel_ll_mcu
 
 USEMODULE_INCLUDES_lcd := $(LAST_MAKEFILEDIR)/include
 USEMODULE_INCLUDES += $(USEMODULE_INCLUDES_lcd)

drivers/lcd/include/lcd_internal.h

@@ -35,6 +35,7 @@ extern "C" {
  */
 #define LCD_CMD_SWRESET         0x01    /**< Software reset */
 #define LCD_CMD_RDDIDIF         0x04    /**< Read display ID */
+#define LCD_CMD_RDDST           0x09    /**< Read display status */
 #define LCD_CMD_SLPIN           0x10    /**< Enter sleep mode */
 #define LCD_CMD_SLPOUT          0x11    /**< Sleep out */
 #define LCD_CMD_NORON           0x13    /**< Normal display mode on */

drivers/lcd/include/lcd_ll_par_gpio.h

@@ -0,0 +1,100 @@
+/*
+ * Copyright (C) 2023 Gunar Schorcht
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+#if !DOXYGEN    /* hide from documentation */
+
+/**
+ * @ingroup     drivers_lcd
+ *
+ * @brief       GPIO-driven low-level parallel interface implementation
+ *
+ * @{
+ * @file
+ * @author      Gunar Schorcht <gunar@schorcht.net>
+ */
+
+#ifndef LCD_LL_PAR_GPIO_H
+#define LCD_LL_PAR_GPIO_H
+
+#include <assert.h>
+
+#include "lcd.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief   Initialize the GPIOs of the GPIO-driven low-level parallel interface
+ *
+ * @param[in]   dev     device descriptor
+ */
+
+void lcd_ll_par_gpio_init(lcd_t *dev);
+
+/**
+ * @brief   Set the direction of the data GPIOs of the low-level parallel interface
+ *
+ * @param[in]   dev     device descriptor
+ * @param[in]   output  set to output mode if true and to input mode otherwise
+ */
+void lcd_ll_par_gpio_set_data_dir(lcd_t *dev, bool output);
+
+/**
+ * @brief   Write command using the MCU-driven low-level parallel interface
+ *
+ * @param[in]   dev     device descriptor
+ * @param[in]   cmd     command
+ * @param[in]   cont    operation is continued
+ */
+void lcd_ll_par_gpio_cmd_start(lcd_t *dev, uint8_t cmd, bool cont);
+
+/**
+ * @brief   Write a byte to the GPIO-driven low-level parallel interface
+ *
+ * @param[in]   dev     device descriptor
+ * @param[in]   cont    operation is continued
+ * @param[in]   out     byte to be written
+ */
+void lcd_ll_par_gpio_write_byte(lcd_t *dev, bool cont, uint8_t out);
+
+/**
+ * @brief   Write a word to the GPIO-driven low-level parallel interface
+ *
+ * @param[in]   dev     device descriptor
+ * @param[in]   cont    operation is continued
+ * @param[in]   out     word to be written
+ */
+void lcd_ll_par_gpio_write_word(lcd_t *dev, bool cont, uint16_t out);
+
+/**
+ * @brief   Read a byte from the GPIO-driven low-level parallel interface
+ *
+ * @param[in]   dev     device descriptor
+ * @param[in]   cont    operation is continued
+ *
+ * @return  read byte
+ */
+uint8_t lcd_ll_par_gpio_read_byte(lcd_t *dev, bool cont);
+
+/**
+ * @brief   Read a word from the GPIO-driven low-level parallel interface
+ *
+ * @param[in]   dev     device descriptor
+ * @param[in]   cont    operation is continued
+ *
+ * @return  read word
+ */
+uint16_t lcd_ll_par_gpio_read_word(lcd_t *dev, bool cont);
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* LCD_LL_PAR_GPIO_H */
+/** @} */
+#endif /* !DOXYGEN */