# HG changeset patch
# User John Tsiombikas <nuclear@member.fsf.org>
# Date 1457068855 0
# Node ID fbab2b3e28da89e0242f62ad99860b21e8b3bfc7

gpio module first test

diff -r 000000000000 -r fbab2b3e28da Makefile
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Makefile	Fri Mar 04 05:20:55 2016 +0000
@@ -0,0 +1,9 @@
+obj-m := gpio.o
+
+.PHONY: all
+all:
+	make -C /lib/modules/$(shell uname -r)/build M=$(shell pwd) modules
+
+.PHONY: clean
+clean:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
diff -r 000000000000 -r fbab2b3e28da gpio.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gpio.c	Fri Mar 04 05:20:55 2016 +0000
@@ -0,0 +1,183 @@
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/io.h>
+#include <linux/fs.h>
+#include <asm/uaccess.h>
+
+/* raspberry pi 2 */
+#define PERI_ADDR	0x3f000000
+#define PERI_SIZE	0x1000000
+
+#define REG_GPIO_BASE		0x200000
+#define REG_GPFSEL_BASE		0x200000
+#define REG_GPSET_BASE		0x20001c
+#define REG_GPCLR_BASE		0x200028
+#define REG_GPLEV_BASE		0x200034
+#define REG_GPPUD			0x200094
+#define REG_GPPUDCLK_BASE	0x200098
+
+#define FSEL_BITS	3
+#define FSEL_INPUT	0
+#define FSEL_OUTPUT	1
+
+#define FSEL_SHIFT(i)	(((i) % 10) * 3)
+#define FSEL_MASK(i)	(3 << FSEL_SHIFT(i))
+
+#define REG(r)	(volatile uint32_t*)((unsigned char*)iomem + (r))
+
+static int gpio_init(void);
+static void gpio_exit(void);
+static int gpio_open(struct inode *inode, struct file *file);
+static int gpio_close(struct inode *inode, struct file *file);
+static ssize_t gpio_write(struct file *file, const char *buf, size_t sz, loff_t *offset);
+
+static inline void set_pin_func(int pin, int func);
+static inline void set_pin_state(int pin, int s);
+static inline int get_pin_state(int pin);
+static inline void set_pullup(int pin, int en);
+static inline void set_pulldown(int pin, int en);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("John Tsiombikas");
+MODULE_DESCRIPTION("gpio module");
+
+module_init(gpio_init);
+module_exit(gpio_exit);
+
+static int major;
+static void *iomem;
+
+static struct file_operations ops = {
+	.open = gpio_open,
+	.release = gpio_close,
+	.write = gpio_write
+};
+
+static int gpio_init(void)
+{
+	if((major = register_chrdev(0, "gpio", &ops)) < 0) {
+		printk("failed to register character device gpio (err: %d)\n", major);
+		return -1;
+	}
+	printk("gpio module registered (device: %d)\n", major);
+	return 0;
+}
+
+static void gpio_exit(void)
+{
+	unregister_chrdev(major, "gpio");
+	printk("gpio exit\n");
+}
+
+static int gpio_open(struct inode *inode, struct file *file)
+{
+	printk("gpio_open called\n");
+	if(iomem) {
+		return -EBUSY;
+	}
+
+	if(!(iomem = ioremap(PERI_ADDR, PERI_SIZE))) {
+		printk("gpio: failed to map peripherals\n");
+		return -EBUSY;
+	}
+	set_pin_func(4, FSEL_OUTPUT);
+	set_pin_state(4, 0);
+
+	try_module_get(THIS_MODULE);
+	return 0;
+}
+
+static int gpio_close(struct inode *inode, struct file *file)
+{
+	if(!iomem) {
+		return -EBADF;
+	}
+
+	iounmap(iomem);
+	iomem = 0;
+
+	module_put(THIS_MODULE);
+	return 0;
+}
+
+static ssize_t gpio_write(struct file *file, const char *buf, size_t sz, loff_t *offset)
+{
+	unsigned char val;
+
+	printk("gpio_write(%d) called\n", sz);
+
+	if(sz < 1) {
+		return 0;
+	}
+	if(copy_from_user(&val, (unsigned char*)buf + sz - 1, 1) != 0) {
+		return -EFAULT;
+	}
+
+	set_pin_state(4, val ? 1 : 0);
+	return sz;
+}
+
+
+static inline void set_pin_func(int pin, int func)
+{
+	int reg_addr, val;
+	reg_addr = REG_GPFSEL_BASE + (pin / 10) * 4;
+	val = *REG(reg_addr);
+	*REG(reg_addr) = (val & FSEL_MASK(pin)) | (func << FSEL_SHIFT(pin));
+}
+
+static inline void set_pin_state(int pin, int s)
+{
+	int reg_addr;
+	int regidx = pin / 32;
+	int bit = pin % 32;
+
+	if(s) {
+		reg_addr = REG_GPSET_BASE + regidx * 4;
+		*REG(reg_addr) |= 1 << bit;
+	} else {
+		reg_addr = REG_GPCLR_BASE + regidx * 4;
+		*REG(reg_addr) |= 1 << bit;
+	}
+}
+
+static inline int get_pin_state(int pin)
+{
+	int reg_addr;
+	int regidx = pin / 32;
+	int bit = pin % 32;
+
+	reg_addr = REG_GPLEV_BASE + regidx * 4;
+	return (*REG(reg_addr) >> bit) & 1;
+}
+
+#define delay_cycles(x) \
+	__asm__ __volatile__ (	\
+		"1:\n\t"	\
+		"subs %0, %0, #1\n\t"	\
+		"bne 1b\n\t"	\
+		:: "r"(x))
+
+static inline void set_pull_updown(int pin, int updown)
+{
+	int regidx = pin / 32;
+	int bit = pin % 32;
+	int clk_addr = REG_GPPUDCLK_BASE + regidx * 4;
+
+	*REG(REG_GPPUD) = updown;
+	delay_cycles(150);
+	*REG(clk_addr) = bit;
+	delay_cycles(150);
+	*REG(REG_GPPUD) = 0;
+	*REG(clk_addr) = 0;
+}
+
+static inline void set_pullup(int pin, int en)
+{
+	set_pull_updown(pin, en ? 2 : 0);
+}
+
+static inline void set_pulldown(int pin, int en)
+{
+	set_pull_updown(pin, en ? 1 : 0);
+}