From 060ffddcf15986572ef87d2ef618a8f2359b0d13 Mon Sep 17 00:00:00 2001
From: Lauchmelder <robert.altner11@gmail.com>
Date: Fri, 10 Jun 2022 22:02:28 +0200
Subject: [PATCH] added checks to pin configuration
---
Makefile | 2 +-
src/checks.c | 37 +++++++++++++++++++++++++++++++++++++
src/checks.h | 11 +++++++++++
src/lcd.c | 41 ++++++++++++++++++++++++++++++-----------
src/lcd.h | 4 +++-
5 files changed, 82 insertions(+), 13 deletions(-)
create mode 100644 src/checks.c
create mode 100644 src/checks.h
diff --git a/Makefile b/Makefile
index 75e147e..fd7cc99 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
obj-m = lcd.o
-lcd-y = src/lcd.o src/io.o
+lcd-y = src/lcd.o src/io.o src/checks.o
KVERSION = $(shell uname -r)
diff --git a/src/checks.c b/src/checks.c
new file mode 100644
index 0000000..3267c70
--- /dev/null
+++ b/src/checks.c
@@ -0,0 +1,37 @@
+#include "checks.h"
+
+#include <linux/module.h>
+#include "lcd.h"
+
+
+#define LCD_MIN_GPIO 2
+#define LCD_MAX_GPIO 27
+
+static int sub_pin = LCD_MIN_GPIO;
+
+int lcd_is_valid_gpio(int pin)
+{
+ return (LCD_MIN_GPIO <= pin && pin <= LCD_MAX_GPIO);
+}
+
+int lcd_assign_gpio(int pin)
+{
+ if(lcd_is_valid_gpio(pin))
+ return pin;
+
+
+ printk(KERN_WARNING "%s: GPIO pin %d is invalid. Using %d instead\n", THIS_MODULE->name, pin, sub_pin);
+ return sub_pin++;
+}
+
+int lcd_check_duplicates(const int* used_pins)
+{
+ int i, j;
+
+ for(i = 0; i < 7; i++)
+ for(j = i + 1; j < 8; j++)
+ if(used_pins[i] == used_pins[j])
+ return -EFAULT;
+
+ return 0;
+}
\ No newline at end of file
diff --git a/src/checks.h b/src/checks.h
new file mode 100644
index 0000000..7d06cfe
--- /dev/null
+++ b/src/checks.h
@@ -0,0 +1,11 @@
+#ifndef _LCD_CHECKS_H
+#define _LCD_CHECKS_H
+
+struct lcd_gpio_config;
+
+int lcd_is_valid_gpio(int pin);
+int lcd_assign_gpio(int pin);
+
+int lcd_check_duplicates(const int* config);
+
+#endif
\ No newline at end of file
diff --git a/src/lcd.c b/src/lcd.c
index 70a93c2..38ad89b 100644
--- a/src/lcd.c
+++ b/src/lcd.c
@@ -5,6 +5,7 @@
#include <linux/gpio.h>
#include "lcd.h"
+#include "checks.h"
MODULE_LICENSE("GPL");
@@ -85,7 +86,10 @@ static int __init lcd_init_module(void)
result = lcd_init_gpio();
if(result < 0)
+ {
+ printk(KERN_ERR "%s: Failed to configure GPIO pins\n", THIS_MODULE->name);
return result;
+ }
printk(KERN_INFO "%s: Module loaded!\n", THIS_MODULE->name);
return result;
@@ -120,26 +124,41 @@ static int __init lcd_init_cdev(void)
static int __init lcd_init_gpio(void)
{
- lcd_validate_gpio();
+ int result, i;
+
+ result = lcd_validate_gpio();
+
+ if(result < 0)
+ return result;
+
+ for(i = 0; i < 8; i++)
+ gpio_direction_output(lcddev.used_pins[i], 0);
- // gpio_direction_output(lcddev.gpio, 0);
- return 0;
+ return result;
}
static int __init lcd_validate_gpio(void)
{
+ int result = 0;
struct lcd_gpio_config* config = &lcddev.config;
+ lcddev.used_pins = (int*)config;
- config->power = pin_power;
- config->rs = pin_rs;
- config->rw = pin_rw;
- config->enable = pin_enable;
+ config->power = lcd_assign_gpio(pin_power);
+ config->rs = lcd_assign_gpio(pin_rs);
+ config->rw = lcd_assign_gpio(pin_rw);
+ config->enable = lcd_assign_gpio(pin_enable);
- memcpy(config->data, pin_data, 4 * sizeof(int));
+ config->data[0] = lcd_assign_gpio(pin_data[0]);
+ config->data[1] = lcd_assign_gpio(pin_data[1]);
+ config->data[2] = lcd_assign_gpio(pin_data[2]);
+ config->data[3] = lcd_assign_gpio(pin_data[3]);
- // TODO: Check if pin configuration is valid
- // - no duplicate pins?
- // - all pin numbers in range?
+ result = lcd_check_duplicates(lcddev.used_pins);
+ if(result < 0)
+ {
+ printk(KERN_ERR "%s: Invalid pin configuration (duplicate pin usage)\n", THIS_MODULE->name);
+ return result;
+ }
return 0;
}
diff --git a/src/lcd.h b/src/lcd.h
index 5b5f58b..2467f1e 100644
--- a/src/lcd.h
+++ b/src/lcd.h
@@ -3,6 +3,7 @@
#include <linux/module.h>
#include <linux/cdev.h>
+#include <linux/semaphore.h>
#define LCD_MAJOR 0
#define LCD_MINOR 0
@@ -18,7 +19,7 @@ struct lcd_gpio_config
int power;
int rs, rw, enable;
int data[4];
-};
+} __attribute__((packed));
struct lcd_dev
{
@@ -26,6 +27,7 @@ struct lcd_dev
struct cdev dev;
struct semaphore sem;
struct lcd_gpio_config config;
+ int* used_pins;
};
#endif
\ No newline at end of file