[SPARC]: Add sun4m LED driver.

This is a forward port of a 2.4.x sun4m LED driver written by Lars
Kotthoff.
Signed-off-by: Lars Kotthoff <metalhead@metalhead.ws>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/Kconfig

@@ -201,6 +201,14 @@ config SUN_OPENPROMFS
 	  Only choose N if you know in advance that you will not need to modify
 	  OpenPROM settings on the running system.
 
+config SPARC_LED
+	tristate "Sun4m LED driver"
+	help
+	  This driver toggles the front-panel LED on sun4m systems
+	  in a user-specifyable manner.  It's state can be probed
+	  by reading /proc/led and it's blinking mode can be changed
+	  via writes to /proc/led
+
 source "fs/Kconfig.binfmt"
 
 config SUNOS_EMUL

arch/sparc/kernel/Makefile

@@ -21,6 +21,7 @@ obj-$(CONFIG_SUN_AUXIO) += auxio.o
 obj-$(CONFIG_PCI) += ebus.o
 obj-$(CONFIG_SUN_PM) += apc.o pmc.o
 obj-$(CONFIG_MODULES) += module.o sparc_ksyms.o
+obj-$(CONFIG_SPARC_LED) += led.o
 
 ifdef CONFIG_SUNOS_EMUL
 obj-y += sys_sunos.o sunos_ioctl.o

arch/sparc/kernel/led.c

+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/proc_fs.h>
+#include <linux/string.h>
+
+#include <asm/auxio.h>
+
+#define LED_MAX_LENGTH 8 /* maximum chars written to proc file */
+
+static inline void led_toggle(void)
+{
+	unsigned char val = get_auxio();
+	unsigned char on, off;
+
+	if (val & AUXIO_LED) {
+		on = 0;
+		off = AUXIO_LED;
+	} else {
+		on = AUXIO_LED;
+		off = 0;
+	}
+
+	set_auxio(on, off);
+}
+
+static struct timer_list led_blink_timer;
+
+static void led_blink(unsigned long timeout)
+{
+	led_toggle();
+
+	/* reschedule */
+	if (!timeout) { /* blink according to load */
+		led_blink_timer.expires = jiffies +
+			((1 + (avenrun[0] >> FSHIFT)) * HZ);
+		led_blink_timer.data = 0;
+	} else { /* blink at user specified interval */
+		led_blink_timer.expires = jiffies + (timeout * HZ);
+		led_blink_timer.data = timeout;
+	}
+	add_timer(&led_blink_timer);
+}
+
+static int led_read_proc(char *buf, char **start, off_t offset, int count,
+			 int *eof, void *data)
+{
+	int len = 0;
+
+	if (get_auxio() & AUXIO_LED)
+		len = sprintf(buf, "on\n");
+	else
+		len = sprintf(buf, "off\n");
+
+	return len;
+}
+
+static int led_write_proc(struct file *file, const char *buffer,
+			  unsigned long count, void *data)
+{
+	char *buf = NULL;
+
+	if (count > LED_MAX_LENGTH)
+		count = LED_MAX_LENGTH;
+
+	buf = kmalloc(sizeof(char) * (count + 1), GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	if (copy_from_user(buf, buffer, count)) {
+		kfree(buf);
+		return -EFAULT;
+	}
+
+	buf[count] = '\0';
+
+	/* work around \n when echo'ing into proc */
+	if (buf[count - 1] == '\n')
+		buf[count - 1] = '\0';
+
+	/* before we change anything we want to stop any running timers,
+	 * otherwise calls such as on will have no persistent effect
+	 */
+	del_timer_sync(&led_blink_timer);
+
+	if (!strcmp(buf, "on")) {
+		auxio_set_led(AUXIO_LED_ON);
+	} else if (!strcmp(buf, "toggle")) {
+		led_toggle();
+	} else if ((*buf > '0') && (*buf <= '9')) {
+		led_blink(simple_strtoul(buf, NULL, 10));
+	} else if (!strcmp(buf, "load")) {
+		led_blink(0);
+	} else {
+		auxio_set_led(AUXIO_LED_OFF);
+	}
+
+	kfree(buf);
+
+	return count;
+}
+
+static struct proc_dir_entry *led;
+
+#define LED_VERSION	"0.1"
+
+static int __init led_init(void)
+{
+	init_timer(&led_blink_timer);
+	led_blink_timer.function = led_blink;
+
+	led = create_proc_entry("led", 0, NULL);
+	if (!led)
+		return -ENOMEM;
+
+	led->read_proc = led_read_proc; /* reader function */
+	led->write_proc = led_write_proc; /* writer function */
+	led->owner = THIS_MODULE;
+
+	printk(KERN_INFO
+	       "led: version %s, Lars Kotthoff <metalhead@metalhead.ws>\n",
+	       LED_VERSION);
+
+	return 0;
+}
+
+static void __exit led_exit(void)
+{
+	remove_proc_entry("led", NULL);
+	del_timer_sync(&led_blink_timer);
+}
+
+module_init(led_init);
+module_exit(led_exit);
+
+MODULE_AUTHOR("Lars Kotthoff <metalhead@metalhead.ws>");
+MODULE_DESCRIPTION("Provides control of the front LED on SPARC systems.");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(LED_VERSION);