[PATCH] chardev: GPIO for SCx200 & PC-8736x: add 'v' command to device-file

Add a new driver command: 'v' which calls gpio_dump() on the pin.  The output
goes to the log, like all other INFO messages in the original driver.  Giving
the user control over the feedback they 'need' is construed to be a
user-friendly feature, and allows us (later) to dial down many INFO messages
to DEBUG log-level.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/i386/kernel/scx200.c

@@ -105,7 +105,6 @@ u32 scx200_gpio_configure(unsigned index, u32 mask, u32 bits)
 	return config;
 }
 
-#if 0
 void scx200_gpio_dump(unsigned index)
 {
         u32 config = scx200_gpio_configure(index, ~0, 0);
@@ -120,7 +119,6 @@ void scx200_gpio_dump(unsigned index)
                (config & 32) ? "HI"     : "LO",		/* trigger on rising/falling edge */
                (config & 64) ? "DEBOUNCE" : "");	/* debounce */
 }
-#endif  /*  0  */
 
 static int __init scx200_init(void)
 {
@@ -141,4 +139,5 @@ module_exit(scx200_cleanup);
 EXPORT_SYMBOL(scx200_gpio_base);
 EXPORT_SYMBOL(scx200_gpio_shadow);
 EXPORT_SYMBOL(scx200_gpio_configure);
+EXPORT_SYMBOL(scx200_gpio_dump);
 EXPORT_SYMBOL(scx200_cb_base);

drivers/char/scx200_gpio.c

@@ -41,6 +41,7 @@ static ssize_t scx200_gpio_write(struct file *file, const char __user *data,
 {
 	unsigned m = iminor(file->f_dentry->d_inode);
 	size_t i;
+	int err = 0;
 
 	for (i = 0; i < len; ++i) {
 		char c;
@@ -77,8 +78,23 @@ static ssize_t scx200_gpio_write(struct file *file, const char __user *data,
 			printk(KERN_INFO NAME ": GPIO%d pull up disabled\n", m);
 			scx200_gpio_configure(m, ~4, 0);
 			break;
+
+		case 'v':
+			/* View Current pin settings */
+			scx200_gpio_dump(m);
+			break;
+		case '\n':
+			/* end of settings string, do nothing */
+			break;
+		default:
+			printk(KERN_ERR NAME
+			       ": GPIO-%2d bad setting: chr<0x%2x>\n", m,
+			       (int)c);
+			err++;
 		}
 	}
+	if (err)
+		return -EINVAL;	/* full string handled, report error */
 
 	return len;
 }