WIP char->platform driver

6 files changed, 66 insertions, 90 deletions

diff --git a/driver/Makefile b/driver/Makefile
index d968e31..7de7424 100644
--- a/driver/Makefile
+++ b/driver/Makefile
@@ -7,7 +7,7 @@ KERNEL := /lib/modules/$(RELEASE)/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
+lork-y += platform.o
 
 all:
 	$(MAKE) -C $(KERNEL) M=$(PWD) modules
diff --git a/driver/config.h b/driver/config.h
index 87eb81f..147e2f3 100644
--- a/driver/config.h
+++ b/driver/config.h
@@ -1,7 +1,5 @@
 #pragma once
 
-#define DRV_NAME "lork"
-
 #include <linux/types.h>
 
 // values from <https://www.ti.com/lit/ug/spruh73q/spruh73q.pdf>
diff --git a/driver/main.c b/driver/main.c
index 226f158..a322616 100644
--- a/driver/main.c
+++ b/driver/main.c
@@ -1,98 +1,54 @@
-#include <linux/cdev.h>
 #include <linux/init.h>
-#include <linux/module.h>
 #include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
 
-#include "fopdrv.h"
-#include "config.h"
+#include "platform.h"
 
-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 const struct of_device_id lork_ids[] = {
+	{ .compatible = "gpio-extern" },
+	{},
 };
 
-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;
+struct platform_driver lork_driver = {
+	.probe = lork_probe,
+	.remove = lork_remove,
+	.driver = {
+		.name = "gpio-extern",
+		.owner = THIS_MODULE,
+		.of_match_table = of_match_ptr(lork_ids),
 	}
+};
 
-	// 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);
-
-	// printk("%s() -> 0 (%d:%d)\n", __PRETTY_FUNCTION__, MAJOR(node), MINOR(node));
-
-	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 int mod_init(void) {
+	printk("%s()\n", __PRETTY_FUNCTION__);
+
+	// // 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 platform_driver_register(&lork_driver);
 }
 
 static void mod_exit(void) {
-	device_destroy(class, node);
-	cdev_del(cdev);
-	class_destroy(class);
-	// printk("%s()\n", __PRETTY_FUNCTION__);
+	printk("%s()\n", __PRETTY_FUNCTION__);
+	platform_driver_unregister(&lork_driver);
 }
 
 module_init(mod_init);
diff --git a/driver/platform.c b/driver/platform.c
new file mode 100644
index 0000000..85aefec
--- /dev/null
+++ b/driver/platform.c
@@ -0,0 +1,12 @@
+#include "platform.h"
+
+int lork_probe(struct platform_device* dev) {
+	printk("%s(%s)\n", __PRETTY_FUNCTION__, dev->name);
+	return 0;
+}
+
+int lork_remove(struct platform_device* dev) {
+	printk("%s(%s)\n", __PRETTY_FUNCTION__, dev->name);
+	return 0;
+}
+
diff --git a/driver/platform.h b/driver/platform.h
new file mode 100644
index 0000000..3faaad5
--- /dev/null
+++ b/driver/platform.h
@@ -0,0 +1,8 @@
+#pragma once
+
+#include <linux/types.h>
+#include <linux/platform_device.h>
+
+int lork_probe(struct platform_device*);
+int lork_remove(struct platform_device*);
+
diff --git a/dts/am335x-boneblack-uboot.dts b/dts/am335x-boneblack-uboot.dts
index 8d140c0..e02de51 100644
--- a/dts/am335x-boneblack-uboot.dts
+++ b/dts/am335x-boneblack-uboot.dts
@@ -1,4 +1,4 @@
-#include <dt-bindings/gpio/gpio.h>
+#include <dt-bindings/gpio/gpio.h> // GPIO_ACTIVE_HIGH
 
 /dts-v1/;
 
@@ -3893,9 +3893,11 @@
 		vmmcsd_fixed = "/fixedregulator0";
 	};
 
-	led_extern {
+	// this section is visible at runtime under
+	// /sys/firmware/devicetree/base/lork
+	lork {
 		compatible = "gpio-extern";
-		label = "lork-gpio";
+		// label = "lork-gpio";
 		gpios = <&gpio1 18 GPIO_ACTIVE_HIGH>;
 	};
 };