From 0d7259fe81e8c41fa3c98789dd6500ac6a7f81e3 Mon Sep 17 00:00:00 2001
From: Ciro Santilli <ciro.santilli@gmail.com>
Date: Sat, 11 Nov 2017 11:11:06 +0000
Subject: [PATCH] Remove runqemu from build... document platform_device.c a bit
 further, add a modprobe.conf test

---
 build                            |  1 -
 kernel_module/params.c           |  8 ++++++++
 kernel_module/platform_device.c  | 11 +++++++++--
 rootfs_overlay/etc/modprobe.conf |  4 ++++
 4 files changed, 21 insertions(+), 3 deletions(-)
 create mode 100644 rootfs_overlay/etc/modprobe.conf

diff --git a/build b/build
index 5baac1a..943e4d5 100755
--- a/build
+++ b/build
@@ -74,4 +74,3 @@ time \
   all \
 ;
 cd ..
-./runqemu "$@"
diff --git a/kernel_module/params.c b/kernel_module/params.c
index a01f13d..5e17416 100644
--- a/kernel_module/params.c
+++ b/kernel_module/params.c
@@ -19,6 +19,14 @@ Those parameters can also be read and modified at runtime from /sys.
 	modinfo
 	/params.ko
 	# Output contains MODULE_PARAM_DESC descriptions.
+
+modprobe insertion can also set default parameters via the /etc/modprobe.conf file. So:
+
+	modprobe params
+
+Outputs:
+
+	12 34
 */
 
 #include <linux/delay.h> /* usleep_range */
diff --git a/kernel_module/platform_device.c b/kernel_module/platform_device.c
index e0347de..005eda3 100644
--- a/kernel_module/platform_device.c
+++ b/kernel_module/platform_device.c
@@ -1,7 +1,12 @@
 /*
 Only works for ARM.
 
-Uses the hw/misc/lkmc_platform_device.c minimal device added in our QEMU fork.
+Uses:
+
+-   hw/misc/lkmc_platform_device.c minimal device added in our QEMU fork
+
+-   the device tree entry we added to our Linux kernel fork:
+	https://github.com/cirosantilli/linux/blob/361bb623671a52a36a077a6dd45843389a687a33/arch/arm/boot/dts/versatile-pb.dts#L42
 
 See: https://stackoverflow.com/questions/28315265/how-to-add-a-new-device-in-qemu-source-code/44612957#44612957
 
@@ -49,7 +54,7 @@ static int lkmc_platform_device_probe(struct platform_device *pdev)
 
 	dev_info(dev, "probe\n");
 
-	/* Play with our custom poperty. */
+	/* Play with our custom device tree poperty. */
 	if (of_property_read_u32(np, "lkmc-asdf", &asdf) ) {
 		dev_err(dev, "of_property_read_u32\n");
 		return -EINVAL;
@@ -100,6 +105,8 @@ static int lkmc_platform_device_remove(struct platform_device *pdev)
 }
 
 static const struct of_device_id of_lkmc_platform_device_match[] = {
+	/* This tells our driver which device tree node it will use.
+	 * It matches the kmc_platform_device@XXXX entry that we added to the device tree. */
 	{ .compatible = "lkmc_platform_device", },
 	{},
 };
diff --git a/rootfs_overlay/etc/modprobe.conf b/rootfs_overlay/etc/modprobe.conf
new file mode 100644
index 0000000..86f7cab
--- /dev/null
+++ b/rootfs_overlay/etc/modprobe.conf
@@ -0,0 +1,4 @@
+# Default parameters when loading modules.
+# Especially important due to loading module dependencies:
+# how else would you specify their parameters?
+options params i=12 j=34