1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/Makefile	Fri Mar 04 05:20:55 2016 +0000
     1.3 @@ -0,0 +1,9 @@
     1.4 +obj-m := gpio.o
     1.5 +
     1.6 +.PHONY: all
     1.7 +all:
     1.8 +	make -C /lib/modules/$(shell uname -r)/build M=$(shell pwd) modules
     1.9 +
    1.10 +.PHONY: clean
    1.11 +clean:
    1.12 +	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

     2.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     2.2 +++ b/gpio.c	Fri Mar 04 05:20:55 2016 +0000
     2.3 @@ -0,0 +1,183 @@
     2.4 +#include <linux/module.h>
     2.5 +#include <linux/kernel.h>
     2.6 +#include <linux/io.h>
     2.7 +#include <linux/fs.h>
     2.8 +#include <asm/uaccess.h>
     2.9 +
    2.10 +/* raspberry pi 2 */
    2.11 +#define PERI_ADDR	0x3f000000
    2.12 +#define PERI_SIZE	0x1000000
    2.13 +
    2.14 +#define REG_GPIO_BASE		0x200000
    2.15 +#define REG_GPFSEL_BASE		0x200000
    2.16 +#define REG_GPSET_BASE		0x20001c
    2.17 +#define REG_GPCLR_BASE		0x200028
    2.18 +#define REG_GPLEV_BASE		0x200034
    2.19 +#define REG_GPPUD			0x200094
    2.20 +#define REG_GPPUDCLK_BASE	0x200098
    2.21 +
    2.22 +#define FSEL_BITS	3
    2.23 +#define FSEL_INPUT	0
    2.24 +#define FSEL_OUTPUT	1
    2.25 +
    2.26 +#define FSEL_SHIFT(i)	(((i) % 10) * 3)
    2.27 +#define FSEL_MASK(i)	(3 << FSEL_SHIFT(i))
    2.28 +
    2.29 +#define REG(r)	(volatile uint32_t*)((unsigned char*)iomem + (r))
    2.30 +
    2.31 +static int gpio_init(void);
    2.32 +static void gpio_exit(void);
    2.33 +static int gpio_open(struct inode *inode, struct file *file);
    2.34 +static int gpio_close(struct inode *inode, struct file *file);
    2.35 +static ssize_t gpio_write(struct file *file, const char *buf, size_t sz, loff_t *offset);
    2.36 +
    2.37 +static inline void set_pin_func(int pin, int func);
    2.38 +static inline void set_pin_state(int pin, int s);
    2.39 +static inline int get_pin_state(int pin);
    2.40 +static inline void set_pullup(int pin, int en);
    2.41 +static inline void set_pulldown(int pin, int en);
    2.42 +
    2.43 +MODULE_LICENSE("GPL");
    2.44 +MODULE_AUTHOR("John Tsiombikas");
    2.45 +MODULE_DESCRIPTION("gpio module");
    2.46 +
    2.47 +module_init(gpio_init);
    2.48 +module_exit(gpio_exit);
    2.49 +
    2.50 +static int major;
    2.51 +static void *iomem;
    2.52 +
    2.53 +static struct file_operations ops = {
    2.54 +	.open = gpio_open,
    2.55 +	.release = gpio_close,
    2.56 +	.write = gpio_write
    2.57 +};
    2.58 +
    2.59 +static int gpio_init(void)
    2.60 +{
    2.61 +	if((major = register_chrdev(0, "gpio", &ops)) < 0) {
    2.62 +		printk("failed to register character device gpio (err: %d)\n", major);
    2.63 +		return -1;
    2.64 +	}
    2.65 +	printk("gpio module registered (device: %d)\n", major);
    2.66 +	return 0;
    2.67 +}
    2.68 +
    2.69 +static void gpio_exit(void)
    2.70 +{
    2.71 +	unregister_chrdev(major, "gpio");
    2.72 +	printk("gpio exit\n");
    2.73 +}
    2.74 +
    2.75 +static int gpio_open(struct inode *inode, struct file *file)
    2.76 +{
    2.77 +	printk("gpio_open called\n");
    2.78 +	if(iomem) {
    2.79 +		return -EBUSY;
    2.80 +	}
    2.81 +
    2.82 +	if(!(iomem = ioremap(PERI_ADDR, PERI_SIZE))) {
    2.83 +		printk("gpio: failed to map peripherals\n");
    2.84 +		return -EBUSY;
    2.85 +	}
    2.86 +	set_pin_func(4, FSEL_OUTPUT);
    2.87 +	set_pin_state(4, 0);
    2.88 +
    2.89 +	try_module_get(THIS_MODULE);
    2.90 +	return 0;
    2.91 +}
    2.92 +
    2.93 +static int gpio_close(struct inode *inode, struct file *file)
    2.94 +{
    2.95 +	if(!iomem) {
    2.96 +		return -EBADF;
    2.97 +	}
    2.98 +
    2.99 +	iounmap(iomem);
   2.100 +	iomem = 0;
   2.101 +
   2.102 +	module_put(THIS_MODULE);
   2.103 +	return 0;
   2.104 +}
   2.105 +
   2.106 +static ssize_t gpio_write(struct file *file, const char *buf, size_t sz, loff_t *offset)
   2.107 +{
   2.108 +	unsigned char val;
   2.109 +
   2.110 +	printk("gpio_write(%d) called\n", sz);
   2.111 +
   2.112 +	if(sz < 1) {
   2.113 +		return 0;
   2.114 +	}
   2.115 +	if(copy_from_user(&val, (unsigned char*)buf + sz - 1, 1) != 0) {
   2.116 +		return -EFAULT;
   2.117 +	}
   2.118 +
   2.119 +	set_pin_state(4, val ? 1 : 0);
   2.120 +	return sz;
   2.121 +}
   2.122 +
   2.123 +
   2.124 +static inline void set_pin_func(int pin, int func)
   2.125 +{
   2.126 +	int reg_addr, val;
   2.127 +	reg_addr = REG_GPFSEL_BASE + (pin / 10) * 4;
   2.128 +	val = *REG(reg_addr);
   2.129 +	*REG(reg_addr) = (val & FSEL_MASK(pin)) | (func << FSEL_SHIFT(pin));
   2.130 +}
   2.131 +
   2.132 +static inline void set_pin_state(int pin, int s)
   2.133 +{
   2.134 +	int reg_addr;
   2.135 +	int regidx = pin / 32;
   2.136 +	int bit = pin % 32;
   2.137 +
   2.138 +	if(s) {
   2.139 +		reg_addr = REG_GPSET_BASE + regidx * 4;
   2.140 +		*REG(reg_addr) |= 1 << bit;
   2.141 +	} else {
   2.142 +		reg_addr = REG_GPCLR_BASE + regidx * 4;
   2.143 +		*REG(reg_addr) |= 1 << bit;
   2.144 +	}
   2.145 +}
   2.146 +
   2.147 +static inline int get_pin_state(int pin)
   2.148 +{
   2.149 +	int reg_addr;
   2.150 +	int regidx = pin / 32;
   2.151 +	int bit = pin % 32;
   2.152 +
   2.153 +	reg_addr = REG_GPLEV_BASE + regidx * 4;
   2.154 +	return (*REG(reg_addr) >> bit) & 1;
   2.155 +}
   2.156 +
   2.157 +#define delay_cycles(x) \
   2.158 +	__asm__ __volatile__ (	\
   2.159 +		"1:\n\t"	\
   2.160 +		"subs %0, %0, #1\n\t"	\
   2.161 +		"bne 1b\n\t"	\
   2.162 +		:: "r"(x))
   2.163 +
   2.164 +static inline void set_pull_updown(int pin, int updown)
   2.165 +{
   2.166 +	int regidx = pin / 32;
   2.167 +	int bit = pin % 32;
   2.168 +	int clk_addr = REG_GPPUDCLK_BASE + regidx * 4;
   2.169 +
   2.170 +	*REG(REG_GPPUD) = updown;
   2.171 +	delay_cycles(150);
   2.172 +	*REG(clk_addr) = bit;
   2.173 +	delay_cycles(150);
   2.174 +	*REG(REG_GPPUD) = 0;
   2.175 +	*REG(clk_addr) = 0;
   2.176 +}
   2.177 +
   2.178 +static inline void set_pullup(int pin, int en)
   2.179 +{
   2.180 +	set_pull_updown(pin, en ? 2 : 0);
   2.181 +}
   2.182 +
   2.183 +static inline void set_pulldown(int pin, int en)
   2.184 +{
   2.185 +	set_pull_updown(pin, en ? 1 : 0);
   2.186 +}