From 15a4f817f22c5ff2f4808961814fcad8fe72103a Mon Sep 17 00:00:00 2001
From: Lauchmelder <robert.altner11@gmail.com>
Date: Fri, 10 Jun 2022 19:07:50 +0200
Subject: [PATCH] added basic pin config for lcd screen

---
 pins.txt  | 10 +++++++++
 src/io.c  | 11 +++++++---
 src/lcd.c | 61 +++++++++++++++++++++++++++++++++++++++++++------------
 src/lcd.h | 15 ++++++++++++--
 4 files changed, 79 insertions(+), 18 deletions(-)
 create mode 100644 pins.txt

diff --git a/pins.txt b/pins.txt
new file mode 100644
index 0000000..36840af
--- /dev/null
+++ b/pins.txt
@@ -0,0 +1,10 @@
+Power   - 14
+
+RS      - 11
+R/W     - 09
+E       - 10
+
+DB4     - 26
+DB5     - 19
+DB6     - 13
+DB7     - 06
\ No newline at end of file
diff --git a/src/io.c b/src/io.c
index 8920288..b363f24 100644
--- a/src/io.c
+++ b/src/io.c
@@ -24,6 +24,7 @@ ssize_t lcd_write(struct file* filp, const char __user* buf, size_t count, loff_
     char* cmd_start = NULL;
     char* cmd_end = NULL;
     ssize_t retval = 0;
+    struct lcd_gpio_config* config;
 
     if(down_interruptible(&dev->sem))
         return retval;
@@ -47,14 +48,18 @@ ssize_t lcd_write(struct file* filp, const char __user* buf, size_t count, loff_
     cmd_start = kern_buf;
     cmd_end = kern_buf;
 
+    config = &dev->config;
+
     while(advance_ptr(kern_buf, count, &cmd_end))
     {
         *cmd_end = '\0';
 
         if(strcmp(cmd_start, "0") == 0)
-            gpio_set_value(dev->gpio, 0);
-        else if(strcmp(cmd_start, "1") == 0)
-            gpio_set_value(dev->gpio, 1);
+            gpio_set_value(config->power, 0);
+        else if(strcmp(cmd_start, "1") == 0) {
+            printk(KERN_DEBUG "%s: Setting output of gpio %d to 1", THIS_MODULE->name, config->power);
+            gpio_set_value(config->power, 1);
+        }
         else
             printk(KERN_WARNING "%s: Unrecognized command \"%s\"\n", THIS_MODULE->name, cmd_start);
 
diff --git a/src/lcd.c b/src/lcd.c
index 74fab78..70a93c2 100644
--- a/src/lcd.c
+++ b/src/lcd.c
@@ -8,19 +8,34 @@
 
 MODULE_LICENSE("GPL");
 
-int lcd_major = LCD_MAJOR;
-int lcd_minor = LCD_MINOR;
-int lcd_gpio  = LCD_GPIO;
+static int lcd_major = LCD_MAJOR;
+static int lcd_minor = LCD_MINOR;
 
 module_param(lcd_major, int, S_IRUGO);
 module_param(lcd_minor, int, S_IRUGO);
-module_param(lcd_gpio,  int, S_IRUGO);
+
+static int pin_power = LCD_PIN_POWER;
+module_param(pin_power, int, S_IRUGO);
+
+static int pin_rs = LCD_PIN_REGISTER_SELECT;
+module_param(pin_rs, int, S_IRUGO);
+
+static int pin_rw = LCD_PIN_READ_WRITE;
+module_param(pin_rw, int, S_IRUGO);
+
+static int pin_enable = LCD_PIN_ENABLE;
+module_param(pin_enable, int, S_IRUGO);
+
+static int pin_data[4] = LCD_PIN_DATA;
+static int count;
+module_param_array(pin_data, int, &count, S_IRUGO);
 
 static struct lcd_dev lcddev = { 0 };
-static int  __init lcd_init_cdev(void);
-static void __exit lcd_exit_cdev(void);
+static int __init lcd_init_cdev(void);
+static int __init lcd_init_gpio(void);
+static int __init lcd_validate_gpio(void);
 
-static int  __init lcd_init_gpio(void);
+static void __exit lcd_exit_cdev(void);
 static void __exit lcd_exit_gpio(void);
 
 extern loff_t   lcd_llseek  (struct file*, loff_t, int);
@@ -103,17 +118,37 @@ static int __init lcd_init_cdev(void)
     return result;
 }
 
+static int  __init lcd_init_gpio(void)
+{
+    lcd_validate_gpio();
+
+    // gpio_direction_output(lcddev.gpio, 0);
+    return 0;
+}
+
+static int __init lcd_validate_gpio(void)
+{
+    struct lcd_gpio_config* config = &lcddev.config;
+
+    config->power  = pin_power;
+    config->rs     = pin_rs;
+    config->rw     = pin_rw;
+    config->enable = pin_enable;
+
+    memcpy(config->data, pin_data, 4 * sizeof(int));
+
+    // TODO: Check if pin configuration is valid
+    //  - no duplicate pins?
+    //  - all pin numbers in range?
+
+    return 0;
+}
+
 static void __exit lcd_exit_cdev(void)
 {
     cdev_del(&lcddev.dev);
 }
 
-static int  __init lcd_init_gpio(void)
-{
-    lcddev.gpio = 18;
-    gpio_direction_output(lcddev.gpio, 0);
-    return 0;
-}
 
 static void __exit lcd_exit_gpio(void)
 {
diff --git a/src/lcd.h b/src/lcd.h
index f749317..5b5f58b 100644
--- a/src/lcd.h
+++ b/src/lcd.h
@@ -7,14 +7,25 @@
 #define LCD_MAJOR 0
 #define LCD_MINOR 0
 
-#define LCD_GPIO 18
+#define LCD_PIN_POWER           14
+#define LCD_PIN_REGISTER_SELECT 11
+#define LCD_PIN_READ_WRITE      9
+#define LCD_PIN_ENABLE          10
+#define LCD_PIN_DATA            { 26, 19, 13, 06 }
+
+struct lcd_gpio_config
+{
+    int power;
+    int rs, rw, enable;
+    int data[4];
+};
 
 struct lcd_dev
 {
     dev_t devno;
     struct cdev dev;
     struct semaphore sem;
-    int gpio;
+    struct lcd_gpio_config config;
 };
 
 #endif
\ No newline at end of file