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