OMAP: UART: Add sysfs interface for adjusting UART sleep timeout

This patch makes it possible to change uart sleep timeout. New sysfs
entry is added (/sys/devices/platform/serial8250.0/sleep_timeout)

Also default timeout is increased to 5 second to make serial console
more usable.

Original patch was written by Tero Kristo some time ago.

Signed-off-by: Jouni Hogander <jouni.hogander@nokia.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
index b834b7ebde563f697d18ed2225e390982cb5adfa..7f9a50da55f5b4cc0d13920a2aa6752574e4532b 100644 (file)
--- a/arch/arm/mach-omap2/serial.c
+++ b/arch/arm/mach-omap2/serial.c
@@ -30,7 +30,7 @@
 #include "pm.h"
 #include "prm-regbits-34xx.h"
 
-#define DEFAULT_TIMEOUT (2 * HZ)
+#define DEFAULT_TIMEOUT (5 * HZ)
 
 struct omap_uart_state {
        int num;
@@ -340,6 +340,8 @@ static irqreturn_t omap_uart_interrupt(int irq, void *dev_id)
        return IRQ_NONE;
 }
 
+static u32 sleep_timeout = DEFAULT_TIMEOUT;
+
 static void omap_uart_idle_init(struct omap_uart_state *uart)
 {
        u32 v;
@@ -347,7 +349,7 @@ static void omap_uart_idle_init(struct omap_uart_state *uart)
        int ret;
 
        uart->can_sleep = 0;
-       uart->timeout = DEFAULT_TIMEOUT;
+       uart->timeout = sleep_timeout;
        setup_timer(&uart->timer, omap_uart_idle_timer,
                    (unsigned long) uart);
        mod_timer(&uart->timer, jiffies + uart->timeout);
@@ -427,6 +429,33 @@ static void omap_uart_idle_init(struct omap_uart_state *uart)
        WARN_ON(ret);
 }
 
+static ssize_t sleep_timeout_show(struct kobject *kobj,
+                                 struct kobj_attribute *attr,
+                                 char *buf)
+{
+       return sprintf(buf, "%u\n", sleep_timeout / HZ);
+}
+
+static ssize_t sleep_timeout_store(struct kobject *kobj,
+                                  struct kobj_attribute *attr,
+                                  const char *buf, size_t n)
+{
+       struct omap_uart_state *uart;
+       unsigned int value;
+
+       if (sscanf(buf, "%u", &value) != 1) {
+               printk(KERN_ERR "sleep_timeout_store: Invalid value\n");
+               return -EINVAL;
+       }
+       sleep_timeout = value * HZ;
+       list_for_each_entry(uart, &uart_list, node)
+               uart->timeout = sleep_timeout;
+       return n;
+}
+
+static struct kobj_attribute sleep_timeout_attr =
+       __ATTR(sleep_timeout, 0644, sleep_timeout_show, sleep_timeout_store);
+
 #else
 static inline void omap_uart_idle_init(struct omap_uart_state *uart) {}
 #endif /* CONFIG_PM */
@@ -496,6 +525,15 @@ static struct platform_device serial_device = {
 
 static int __init omap_init(void)
 {
-       return platform_device_register(&serial_device);
+       int ret;
+
+       ret = platform_device_register(&serial_device);
+
+#ifdef CONFIG_PM
+       if (!ret)
+               ret = sysfs_create_file(&serial_device.dev.kobj,
+                                       &sleep_timeout_attr.attr);
+#endif
+       return ret;
 }
 arch_initcall(omap_init);