rename folders

9 files changed, 327 insertions, 0 deletions

diff --git a/driver/Makefile b/driver/Makefile
new file mode 100644
index 0000000..d968e31
--- /dev/null
+++ b/driver/Makefile
@@ -0,0 +1,21 @@
+RELEASE := $(shell uname -r)
+KERNEL := /lib/modules/$(RELEASE)/build
+# PWD doesn't have to be defined as it's inherited from the current environment
+# MAKE shouldn't be defined as it's special in GNU make
+
+# the names of these variables are required by the kernel's (imo weird) build
+# system, see [kbuild-obj-var] and [kbuild-module-makefile] in ../readme.md
+obj-m += lork.o
+lork-y += main.o
+lork-y += fopdrv.o
+
+all:
+	$(MAKE) -C $(KERNEL) M=$(PWD) modules
+
+# the generated compile_commands.json needs to be edited to point to the kernel
+# folder as working directory because the include paths are relative
+compile_commands.json:
+	compiledb -o $@.tmp make -Bn
+	jq --arg dir $(KERNEL) '.[].directory = $$dir' $@.tmp > $@
+	$(RM) $@.tmp
+
diff --git a/driver/config.h b/driver/config.h
new file mode 100644
index 0000000..dbe3a86
--- /dev/null
+++ b/driver/config.h
@@ -0,0 +1,26 @@
+#pragma once
+
+#define DRV_NAME "lork"
+
+#include <linux/types.h>
+
+// values from <https://www.ti.com/lit/ug/spruh73q/spruh73q.pdf>
+
+typedef uint32_t ti_am335x_word_t;
+
+// p. 180: "Control Module"
+#define TI_AM335X_CM_ADDR 0x44E10000
+// p. 182: "GPIO1"
+#define TI_AM335X_GPIO1_ADDR 0x4804C000
+// p. 1459: "conf_gpmc_a3"
+#define TI_AM335X_CM_GPMC_A3_ADDR (TI_AM335X_CM_ADDR + 0x84C)
+
+// p. 4990, variable names copied as-is
+#define GPIO_OE (0x134 / (sizeof(ti_am335x_word_t)))
+#define GPIO_DATAIN (0x138 / (sizeof(ti_am335x_word_t)))
+#define GPIO_CLEARDATAOUT (0x190 / (sizeof(ti_am335x_word_t)))
+#define GPIO_SETDATAOUT (0x194 / (sizeof(ti_am335x_word_t)))
+// total size of GPIO registers from p. 4990 (in bytes)
+#define GPIO_REG_SIZE 0x198
+
+#define PIN 19
diff --git a/driver/fopdrv.c b/driver/fopdrv.c
new file mode 100644
index 0000000..18a1d35
--- /dev/null
+++ b/driver/fopdrv.c
@@ -0,0 +1,76 @@
+#include <linux/io.h>
+
+#include "fopdrv.h"
+#include "config.h"
+
+bool printed = false;
+
+// driver/char/mem.c read_null (/dev/null)
+ssize_t fop_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) {
+	printk("%s(<file>, <buf>, %u, <ppos>)\n", __PRETTY_FUNCTION__, count);
+
+	if (count < 2) return 0;
+	if (printed) return 0;
+
+	ti_am335x_word_t* gpio1 = ioremap(TI_AM335X_GPIO1_ADDR, GPIO_REG_SIZE);
+	barrier();
+
+	ti_am335x_word_t gpio = ioread32(gpio1 + GPIO_DATAIN); rmb();
+	bool on = (gpio & (1<<PIN)) > 0;
+
+	char output[10];
+	snprintf(output, 10, "%d\n", on);
+
+	if (copy_to_user(buf, output + *ppos, 2))
+		return -EFAULT;
+	*ppos += 2;
+	printed = true;
+	return 2;
+}
+
+ssize_t fop_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) {
+	printk("%s(<file>, <buf>, %u, <ppos>)\n", __PRETTY_FUNCTION__, count);
+
+	// only allow single character as input
+	if (count < 1) return count;
+	if (count > 2) return count;
+
+	// copy buffer for reading (see [kernel-labs-chrdev] in ../readme.md)
+	char input_buf[10];
+	if (copy_from_user(input_buf + *ppos, buf, count))
+		return -EFAULT;
+
+	ti_am335x_word_t* gpio1 = ioremap(TI_AM335X_GPIO1_ADDR, GPIO_REG_SIZE);
+	barrier();
+
+	if (input_buf[0] == '0') {
+		printk("TODO: TURN OFF OUTPUT\n");
+		iowrite32((1<<PIN), gpio1 + GPIO_CLEARDATAOUT); wmb();
+	}
+	if (input_buf[0] == '1') {
+		printk("TODO: TURN ON OUTPUT\n");
+		iowrite32((1<<PIN), gpio1 + GPIO_SETDATAOUT); wmb();
+	}
+
+	iounmap(gpio1);
+
+	return count;
+}
+
+int fop_open(struct inode * inode, struct file * file) {
+	printk("%s(<inode>, <file>)\n", __PRETTY_FUNCTION__);
+	printed = false;
+	return 0;
+	// 0 seems to be a safe return value as it's used in driver/char/mem.c. The
+	// manual page for open(2) says that the system call returns a nonnegative
+	// integer representing the file descriptor on success, but it does not
+	// appears to be required.
+}
+
+int fop_release(struct inode * inode, struct file * file) {
+	printk("%s(<inode>, <file>)\n", __PRETTY_FUNCTION__);
+	return 0;
+	// same as above, but found in driver/char/lp.c
+}
+
+
diff --git a/driver/fopdrv.h b/driver/fopdrv.h
new file mode 100644
index 0000000..f2ca18c
--- /dev/null
+++ b/driver/fopdrv.h
@@ -0,0 +1,11 @@
+#pragma once
+
+#include <linux/fs.h>
+#include <linux/types.h>
+
+// declarations copied from linux/fs.h
+ssize_t fop_read(struct file *, char __user *, size_t, loff_t *);
+ssize_t fop_write(struct file *, const char __user *, size_t, loff_t *);
+int fop_open(struct inode *, struct file *);
+int fop_release(struct inode *, struct file *);
+
diff --git a/driver/main.c b/driver/main.c
new file mode 100644
index 0000000..d8ea7fc
--- /dev/null
+++ b/driver/main.c
@@ -0,0 +1,110 @@
+#include <linux/cdev.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/io.h>
+
+#include "fopdrv.h"
+#include "config.h"
+
+int one = 0;
+module_param(one, int, 0400);
+MODULE_PARM_DESC(one, "first parameter, only printed on init");
+
+int not_named_two = 0;
+module_param_named(two, not_named_two, int, 0400);
+MODULE_PARM_DESC(not_named_two, "second parameter, only printed on init");
+
+struct cdev *cdev;
+struct device *dev;
+struct class *class;
+dev_t node;
+struct file_operations fops = {
+	.read = fop_read,
+	.write = fop_write,
+	.open = fop_open,
+	.release = fop_release,
+};
+
+static int mod_init(void) {
+	int err;
+
+	err = alloc_chrdev_region(&node, 0, 1, DRV_NAME);
+	if (err < 0) {
+		printk(KERN_ERR "alloc_chrdev_region error %d\n", err);
+		goto return_err;
+	}
+
+	class = class_create(DRV_NAME);
+	if (IS_ERR_OR_NULL(class)) {
+		err = PTR_ERR(class);
+		printk(KERN_ERR "class_create error %d\n", err);
+		goto free_class;
+	}
+
+	cdev = cdev_alloc();
+	if (!cdev) {
+		err = ENOMEM;
+		goto free_cdev;
+	}
+
+	cdev->ops = &fops;
+	cdev_init(cdev, &fops);
+	err = cdev_add(cdev, node, 1);
+	if (err < 0) {
+		printk(KERN_ERR "cdev_add error %d\n", err);
+		goto free_cdev;
+	}
+
+	dev = device_create(class, NULL, node, NULL, DRV_NAME);
+	if (IS_ERR_OR_NULL(dev)) {
+		err = PTR_ERR(dev);
+		printk(KERN_ERR "device_create error %d\n", err);
+		goto free_device;
+	}
+
+	printk("%s() -> 0 (%d:%d)\n", __PRETTY_FUNCTION__, MAJOR(node), MINOR(node));
+	printk("one = %d, two = %d\n", one, not_named_two);
+
+	// configure gpio mux
+	uint32_t* conf_gpmc_a3 = ioremap(TI_AM335X_CM_GPMC_A3_ADDR, sizeof(ti_am335x_word_t));
+	if (conf_gpmc_a3 == NULL)
+		return -EINVAL;
+	barrier();
+	uint32_t val = ioread32(conf_gpmc_a3); rmb();
+	val &= ~0x7;
+	val |= 0x7;
+	iowrite32(val, conf_gpmc_a3); wmb();
+	iounmap(conf_gpmc_a3);
+
+	// configure output pin
+	ti_am335x_word_t* gpio1 = ioremap(TI_AM335X_GPIO1_ADDR, GPIO_REG_SIZE);
+	barrier();
+	ti_am335x_word_t oe_reg = ioread32(gpio1 + GPIO_OE); rmb();
+	oe_reg &= ~(1<<PIN); // 0=output
+	iowrite32(oe_reg, gpio1 + GPIO_OE); wmb();
+	iounmap(gpio1);
+
+	return 0;
+
+free_device:
+	device_destroy(class, node);
+free_cdev:
+	cdev_del(cdev);
+free_class:
+	class_destroy(class);
+return_err:
+	printk("%s() -> %d\n", __PRETTY_FUNCTION__, err);
+	return err;
+}
+
+static void mod_exit(void) {
+	device_destroy(class, node);
+	cdev_del(cdev);
+	class_destroy(class);
+	printk("%s()\n", __PRETTY_FUNCTION__);
+}
+
+module_init(mod_init);
+module_exit(mod_exit);
+MODULE_LICENSE("Dual MIT/GPL");
+
diff --git a/driver/test/.gitignore b/driver/test/.gitignore
new file mode 100644
index 0000000..ba2906d
--- /dev/null
+++ b/driver/test/.gitignore
@@ -0,0 +1 @@
+main
diff --git a/driver/test/main.c b/driver/test/main.c
new file mode 100644
index 0000000..b87e56c
--- /dev/null
+++ b/driver/test/main.c
@@ -0,0 +1,56 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <string.h>
+
+int main(int argc, char** argv) {
+	if (geteuid() != 0) {
+		fprintf(stderr, "run me as root!\n");
+		return 1;
+	}
+
+	argc--; // argv[0] is the program name
+	if (argc == 0) {
+		fprintf(stderr, "usage: %s /dev/lork\n", argv[0]);
+		return 1;
+	}
+
+	char* dev = argv[1];
+	const char* input = "test";
+	int fd;
+	ssize_t bytes;
+
+	fd = open(dev, O_RDWR);
+	if (-1 == fd) {
+		fprintf(stderr, "open() failed with code %d\n", errno);
+		return 1;
+	}
+
+	bytes = write(fd, input, strlen(input));
+	if (-1 == bytes) {
+		fprintf(stderr, "write() failed with code %d\n", errno);
+		return 1;
+	}
+	fprintf(stderr, "input \"%s\" to %s (%ld bytes succesful)\n", input, dev, bytes);
+
+	char buf[80];
+	bytes = read(fd, buf, 80);
+	if (-1 == bytes) {
+		fprintf(stderr, "read() failed with code %d\n", errno);
+		return 1;
+	}
+	fprintf(stderr, "output from %s: (%ld bytes)\n", dev, bytes);
+	if (bytes > 0) {
+		if (bytes < 80) buf[bytes] = '\0'; // null terminate string for printf
+		printf("%s\n", buf);
+	}
+
+	if (-1 == close(fd)) {
+		fprintf(stderr, "close() failed with code %d\n", errno);
+		return 1;
+	}
+
+	return 0;
+}
+
diff --git a/driver/test/makefile b/driver/test/makefile
new file mode 100644
index 0000000..3491973
--- /dev/null
+++ b/driver/test/makefile
@@ -0,0 +1,2 @@
+main: main.o
+
diff --git a/driver/test/test.sh b/driver/test/test.sh
new file mode 100755
index 0000000..7dba005
--- /dev/null
+++ b/driver/test/test.sh
@@ -0,0 +1,24 @@
+#!/bin/sh
+
+if [ $(id -u) -ne 0 ] ; then
+	echo "run me as root!" >&2
+	exit 1
+fi
+
+if [ $# -eq 0 ] ; then
+	echo "usage: $0 /dev/lork" >&2
+	exit 1
+fi
+
+DEV="$1"
+INPUT="test"
+
+echo "input \"$INPUT\" to $DEV" >&2
+echo "$INPUT" > "$DEV"
+echo "(EC $?)" >&2
+
+echo "output from $DEV:" >&2
+cat "$DEV"
+echo "(EC $?)" >&2
+
+exit 0