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

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This patch makes it possible to change uart sleep timeout. New sysfs
entry is added (/sys/devices/platform/serial8250.<uart>/sleep_timeout)
Writing zero will disable the timeout feature and prevent UART clocks
from being disabled.

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

Original patch was written by Tero Kristo.

Cc: Tero Kristo <Tero.Kristo@nokia.com>
Signed-off-by: Jouni Hogander <jouni.hogander@nokia.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
This commit is contained in:
Jouni Hogander 2008-12-09 13:36:50 +02:00 committed by Kevin Hilman
parent 4af4016c53
commit ba87a9beae
1 changed files with 51 additions and 4 deletions
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55
arch/arm/mach-omap2/serial.c
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@ -32,7 +32,7 @@
#define UART_OMAP_WER 0x17 /* Wake-up enable register */ #define UART_OMAP_WER 0x17 /* Wake-up enable register */
#define DEFAULT_TIMEOUT (2 * HZ) #define DEFAULT_TIMEOUT (5 * HZ)
struct omap_uart_state { struct omap_uart_state {
int num; int num;
@ -235,7 +235,10 @@ static void omap_uart_block_sleep(struct omap_uart_state *uart)
omap_uart_smart_idle_enable(uart, 0); omap_uart_smart_idle_enable(uart, 0);
uart->can_sleep = 0; uart->can_sleep = 0;
mod_timer(&uart->timer, jiffies + uart->timeout); if (uart->timeout)
mod_timer(&uart->timer, jiffies + uart->timeout);
else
del_timer(&uart->timer);
} }
static void omap_uart_allow_sleep(struct omap_uart_state *uart) static void omap_uart_allow_sleep(struct omap_uart_state *uart)
@ -340,6 +343,8 @@ static irqreturn_t omap_uart_interrupt(int irq, void *dev_id)
return IRQ_NONE; return IRQ_NONE;
} }
static u32 sleep_timeout = DEFAULT_TIMEOUT;
static void omap_uart_idle_init(struct omap_uart_state *uart) static void omap_uart_idle_init(struct omap_uart_state *uart)
{ {
u32 v; u32 v;
@ -347,7 +352,7 @@ static void omap_uart_idle_init(struct omap_uart_state *uart)
int ret; int ret;
uart->can_sleep = 0; uart->can_sleep = 0;
uart->timeout = DEFAULT_TIMEOUT; uart->timeout = sleep_timeout;
setup_timer(&uart->timer, omap_uart_idle_timer, setup_timer(&uart->timer, omap_uart_idle_timer,
(unsigned long) uart); (unsigned long) uart);
mod_timer(&uart->timer, jiffies + uart->timeout); mod_timer(&uart->timer, jiffies + uart->timeout);
@ -427,6 +432,39 @@ static void omap_uart_idle_init(struct omap_uart_state *uart)
WARN_ON(ret); 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;
if (uart->timeout)
mod_timer(&uart->timer, jiffies + uart->timeout);
else
/* A zero value means disable timeout feature */
omap_uart_block_sleep(uart);
}
return n;
}
static struct kobj_attribute sleep_timeout_attr =
__ATTR(sleep_timeout, 0644, sleep_timeout_show, sleep_timeout_store);
#else #else
static inline void omap_uart_idle_init(struct omap_uart_state *uart) {} static inline void omap_uart_idle_init(struct omap_uart_state *uart) {}
#endif /* CONFIG_PM */ #endif /* CONFIG_PM */
@ -496,6 +534,15 @@ static struct platform_device serial_device = {
static int __init omap_init(void) 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); arch_initcall(omap_init);