diff options
Diffstat (limited to 'drivers/char/nsc_gpio.c')
| -rw-r--r-- | drivers/char/nsc_gpio.c | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/drivers/char/nsc_gpio.c b/drivers/char/nsc_gpio.c new file mode 100644 index 000000000..da930c72b --- /dev/null +++ b/drivers/char/nsc_gpio.c @@ -0,0 +1,140 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* linux/drivers/char/nsc_gpio.c + + National Semiconductor common GPIO device-file/VFS methods. + Allows a user space process to control the GPIO pins. + + Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com> + Copyright (c) 2005 Jim Cromie <jim.cromie@gmail.com> +*/ + +#include <linux/fs.h> +#include <linux/module.h> +#include <linux/errno.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/nsc_gpio.h> +#include <linux/platform_device.h> +#include <linux/uaccess.h> +#include <asm/io.h> + +#define NAME "nsc_gpio" + +void nsc_gpio_dump(struct nsc_gpio_ops *amp, unsigned index) +{ + /* retrieve current config w/o changing it */ + u32 config = amp->gpio_config(index, ~0, 0); + + /* user requested via 'v' command, so its INFO */ + dev_info(amp->dev, "io%02u: 0x%04x %s %s %s %s %s %s %s\tio:%d/%d\n", + index, config, + (config & 1) ? "OE" : "TS", /* output-enabled/tristate */ + (config & 2) ? "PP" : "OD", /* push pull / open drain */ + (config & 4) ? "PUE" : "PUD", /* pull up enabled/disabled */ + (config & 8) ? "LOCKED" : "", /* locked / unlocked */ + (config & 16) ? "LEVEL" : "EDGE",/* level/edge input */ + (config & 32) ? "HI" : "LO", /* trigger on rise/fall edge */ + (config & 64) ? "DEBOUNCE" : "", /* debounce */ + + amp->gpio_get(index), amp->gpio_current(index)); +} + +ssize_t nsc_gpio_write(struct file *file, const char __user *data, + size_t len, loff_t *ppos) +{ + unsigned m = iminor(file_inode(file)); + struct nsc_gpio_ops *amp = file->private_data; + struct device *dev = amp->dev; + size_t i; + int err = 0; + + for (i = 0; i < len; ++i) { + char c; + if (get_user(c, data + i)) + return -EFAULT; + switch (c) { + case '0': + amp->gpio_set(m, 0); + break; + case '1': + amp->gpio_set(m, 1); + break; + case 'O': + dev_dbg(dev, "GPIO%d output enabled\n", m); + amp->gpio_config(m, ~1, 1); + break; + case 'o': + dev_dbg(dev, "GPIO%d output disabled\n", m); + amp->gpio_config(m, ~1, 0); + break; + case 'T': + dev_dbg(dev, "GPIO%d output is push pull\n", m); + amp->gpio_config(m, ~2, 2); + break; + case 't': + dev_dbg(dev, "GPIO%d output is open drain\n", m); + amp->gpio_config(m, ~2, 0); + break; + case 'P': + dev_dbg(dev, "GPIO%d pull up enabled\n", m); + amp->gpio_config(m, ~4, 4); + break; + case 'p': + dev_dbg(dev, "GPIO%d pull up disabled\n", m); + amp->gpio_config(m, ~4, 0); + break; + case 'v': + /* View Current pin settings */ + amp->gpio_dump(amp, m); + break; + case '\n': + /* end of settings string, do nothing */ + break; + default: + dev_err(dev, "io%2d bad setting: chr<0x%2x>\n", + m, (int)c); + err++; + } + } + if (err) + return -EINVAL; /* full string handled, report error */ + + return len; +} + +ssize_t nsc_gpio_read(struct file *file, char __user * buf, + size_t len, loff_t * ppos) +{ + unsigned m = iminor(file_inode(file)); + int value; + struct nsc_gpio_ops *amp = file->private_data; + + value = amp->gpio_get(m); + if (put_user(value ? '1' : '0', buf)) + return -EFAULT; + + return 1; +} + +/* common file-ops routines for both scx200_gpio and pc87360_gpio */ +EXPORT_SYMBOL(nsc_gpio_write); +EXPORT_SYMBOL(nsc_gpio_read); +EXPORT_SYMBOL(nsc_gpio_dump); + +static int __init nsc_gpio_init(void) +{ + printk(KERN_DEBUG NAME " initializing\n"); + return 0; +} + +static void __exit nsc_gpio_cleanup(void) +{ + printk(KERN_DEBUG NAME " cleanup\n"); +} + +module_init(nsc_gpio_init); +module_exit(nsc_gpio_cleanup); + +MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>"); +MODULE_DESCRIPTION("NatSemi GPIO Common Methods"); +MODULE_LICENSE("GPL"); |