From 5ce3f5c841eb64854af1c7fe47fac003ca31419a Mon Sep 17 00:00:00 2001
From: lonkaars <loek@pipeframe.xyz>
Date: Tue, 14 May 2024 19:52:38 +0200
Subject: WIP 9.3

---
 driver/Makefile   | 14 +++++++++++++-
 driver/main.c     | 20 -------------------
 driver/platform.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 70 insertions(+), 21 deletions(-)

(limited to 'driver')

diff --git a/driver/Makefile b/driver/Makefile
index 7de7424..f9cb359 100644
--- a/driver/Makefile
+++ b/driver/Makefile
@@ -9,9 +9,17 @@ obj-m += lork.o
 lork-y += main.o
 lork-y += platform.o
 
-all:
+# utility
+ifneq ($(shell id -u),0)
+AS_ROOT := sudo -n
+endif
+.PHONY: FORCE
+
+lork.ko: FORCE
 	$(MAKE) -C $(KERNEL) M=$(PWD) modules
 
+all: lork.ko FORCE
+
 # 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:
@@ -19,3 +27,7 @@ compile_commands.json:
 	jq --arg dir $(KERNEL) '.[].directory = $$dir' $@.tmp > $@
 	$(RM) $@.tmp
 
+poke: lork.ko FORCE
+	$(AS_ROOT) insmod $<
+	$(AS_ROOT) rmmod $<
+
diff --git a/driver/main.c b/driver/main.c
index a322616..76ba1d8 100644
--- a/driver/main.c
+++ b/driver/main.c
@@ -23,26 +23,6 @@ struct platform_driver lork_driver = {
 
 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);
 }
 
diff --git a/driver/platform.c b/driver/platform.c
index 85aefec..da84064 100644
--- a/driver/platform.c
+++ b/driver/platform.c
@@ -1,6 +1,63 @@
 #include "platform.h"
 
+#include <linux/types.h>
+#include <linux/of.h>
+
+#include <dt-bindings/gpio/gpio.h>
+
+// NOTE: i believe any nonzero return value for the probe function is
+// recognized as an error because of
+// <https://github.com/torvalds/linux/blob/a5131c3fdf2608f1c15f3809e201cf540eb28489/drivers/base/platform.c#L1004>
 int lork_probe(struct platform_device* dev) {
+	// read gpios field from device tree
+	uint32_t dt_gpios[3];
+	of_property_read_u32_array(dev->dev.of_node, "gpios", dt_gpios, 3);
+
+	struct device_node* gpio1 = of_find_node_by_phandle(dt_gpios[0]);
+	uint32_t pin = dt_gpios[1];
+	uint32_t gpio_mode = dt_gpios[2];
+	printk("lork: configure pin %u w/ mode 0x%02x\n", pin, gpio_mode);
+
+	// find the multiplexer that controls pin
+	size_t len = of_property_count_u32_elems(gpio1, "gpio-ranges");
+	struct device_node* am33xx_pinmux = NULL;
+	for (size_t i = 0; i < len; i += 4) {
+		uint32_t phandle, pin_start, pin_offset, pin_size;
+		of_property_read_u32_index(gpio1, "gpio-ranges", i+0, &phandle);
+		of_property_read_u32_index(gpio1, "gpio-ranges", i+1, &pin_start);
+		of_property_read_u32_index(gpio1, "gpio-ranges", i+2, &pin_offset);
+		of_property_read_u32_index(gpio1, "gpio-ranges", i+3, &pin_size);
+
+		// get phandle for multiplexer corresponding to configured pin number
+		if (pin_start > pin || pin >= pin_start + pin_size) continue;
+
+		am33xx_pinmux = of_find_node_by_phandle(phandle);
+		printk("0x%02x, %u -> %u + %u\n", phandle, pin_start, pin_offset, pin_size);
+		break;
+	}
+	if (am33xx_pinmux == NULL) return EINVAL;
+
+	// TODO: ???
+
+	// // 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(%s)\n", __PRETTY_FUNCTION__, dev->name);
 	return 0;
 }
-- 
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