[PATCH 1/3] OMAP3: Serial: Improved sleep logic
Kevin Hilman
khilman at deeprootsystems.com
Mon May 3 17:41:09 EDT 2010
From: Tero Kristo <tero.kristo at nokia.com>
This patch contains following improvements:
- Only RX interrupt will now kick the sleep prevent timer
- TX fifo status is checked before disabling clocks, this will prevent
on-going transmission to be cut
- Smartidle is now enabled/disabled only while switching clocks, as having
smartidle enabled while RX/TX prevents any wakeups from being received
from UART module
- Added workqueue for wakeup checks, as jiffy timer access within the
idle loop results into skewed timers as jiffy timers are stopped
- Added garbage_timer for ignoring the first character received during
the first tick after clock enable, this prevents garbage characters to be
received in low sleep states
- omap_uart_enable_irqs() changed to use enable_irq / disable_irq instead
of request / free. Using request/free changes the behavior after first
suspend due to reversed interrupt handler ordering
Signed-off-by: Tero Kristo <tero.kristo at nokia.com>
Signed-off-by: Kevin Hilman <khilman at deeprootsystems.com>
---
arch/arm/mach-omap2/serial.c | 71 ++++++++++++++++++++++++++++++++++++------
1 files changed, 61 insertions(+), 10 deletions(-)
diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
index 3771254..b709cf8 100644
--- a/arch/arm/mach-omap2/serial.c
+++ b/arch/arm/mach-omap2/serial.c
@@ -24,6 +24,7 @@
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/delay.h>
+#include <linux/workqueue.h>
#include <plat/common.h>
#include <plat/board.h>
@@ -49,7 +50,10 @@ struct omap_uart_state {
int num;
int can_sleep;
struct timer_list timer;
+ struct timer_list garbage_timer;
+ struct work_struct wakeup_work;
u32 timeout;
+ u8 garbage_ignore;
void __iomem *wk_st;
void __iomem *wk_en;
@@ -239,6 +243,11 @@ static inline void omap_uart_save_context(struct omap_uart_state *uart) {}
static inline void omap_uart_restore_context(struct omap_uart_state *uart) {}
#endif /* CONFIG_PM && CONFIG_ARCH_OMAP3 */
+#ifdef CONFIG_PM
+static void omap_uart_smart_idle_enable(struct omap_uart_state *uart,
+ int enable);
+#endif
+
static inline void omap_uart_enable_clocks(struct omap_uart_state *uart)
{
if (uart->clocked)
@@ -248,6 +257,9 @@ static inline void omap_uart_enable_clocks(struct omap_uart_state *uart)
clk_enable(uart->fck);
uart->clocked = 1;
omap_uart_restore_context(uart);
+#ifdef CONFIG_PM
+ omap_uart_smart_idle_enable(uart, 0);
+#endif
}
#ifdef CONFIG_PM
@@ -259,8 +271,13 @@ static inline void omap_uart_disable_clocks(struct omap_uart_state *uart)
omap_uart_save_context(uart);
uart->clocked = 0;
+ omap_uart_smart_idle_enable(uart, 1);
clk_disable(uart->ick);
clk_disable(uart->fck);
+ if (uart->garbage_ignore) {
+ del_timer(&uart->garbage_timer);
+ uart->garbage_ignore = 0;
+ }
}
static void omap_uart_enable_wakeup(struct omap_uart_state *uart)
@@ -316,7 +333,6 @@ static void omap_uart_block_sleep(struct omap_uart_state *uart)
{
omap_uart_enable_clocks(uart);
- omap_uart_smart_idle_enable(uart, 0);
uart->can_sleep = 0;
if (uart->timeout)
mod_timer(&uart->timer, jiffies + uart->timeout);
@@ -334,7 +350,6 @@ static void omap_uart_allow_sleep(struct omap_uart_state *uart)
if (!uart->clocked)
return;
- omap_uart_smart_idle_enable(uart, 1);
uart->can_sleep = 1;
del_timer(&uart->timer);
}
@@ -346,18 +361,46 @@ static void omap_uart_idle_timer(unsigned long data)
omap_uart_allow_sleep(uart);
}
+static void omap_uart_garbage_timer(unsigned long data)
+{
+ struct omap_uart_state *uart = (struct omap_uart_state *)data;
+
+ uart->garbage_ignore = 0;
+}
+
+static void omap_uart_wakeup_work(struct work_struct *work)
+{
+ struct omap_uart_state *uart =
+ container_of(work, struct omap_uart_state, wakeup_work);
+
+ omap_uart_block_sleep(uart);
+
+ /* Set up garbage timer to ignore RX during first jiffy */
+ if (uart->timeout)
+ mod_timer(&uart->garbage_timer, jiffies + 1);
+}
+
void omap_uart_prepare_idle(int num)
{
struct omap_uart_state *uart;
list_for_each_entry(uart, &uart_list, node) {
if (num == uart->num && uart->can_sleep) {
- omap_uart_disable_clocks(uart);
+ if (serial_read_reg(uart->p, UART_LSR) &
+ UART_LSR_TEMT)
+ omap_uart_disable_clocks(uart);
return;
}
}
}
+static void serial_wakeup(struct omap_uart_state *uart)
+{
+ if (uart->timeout)
+ uart->garbage_ignore = 1;
+ schedule_work(&uart->wakeup_work);
+}
+
void omap_uart_resume_idle(int num)
{
struct omap_uart_state *uart;
@@ -371,12 +414,12 @@ void omap_uart_resume_idle(int num)
u16 p = omap_ctrl_readw(uart->padconf);
if (p & OMAP3_PADCONF_WAKEUPEVENT0)
- omap_uart_block_sleep(uart);
+ serial_wakeup(uart);
}
/* Check for normal UART wakeup */
if (__raw_readl(uart->wk_st) & uart->wk_mask)
- omap_uart_block_sleep(uart);
+ serial_wakeup(uart);
return;
}
}
@@ -425,7 +468,14 @@ static irqreturn_t omap_uart_interrupt(int irq, void *dev_id)
{
struct omap_uart_state *uart = dev_id;
- omap_uart_block_sleep(uart);
+ /* Check for receive interrupt */
+ while (serial_read_reg(uart->p, UART_LSR) & UART_LSR_DR) {
+ omap_uart_block_sleep(uart);
+ if (uart->garbage_ignore)
+ serial_read_reg(uart->p, UART_RX);
+ else
+ break;
+ }
return IRQ_NONE;
}
@@ -439,6 +489,9 @@ static void omap_uart_idle_init(struct omap_uart_state *uart)
uart->timeout = DEFAULT_TIMEOUT;
setup_timer(&uart->timer, omap_uart_idle_timer,
(unsigned long) uart);
+ setup_timer(&uart->garbage_timer, omap_uart_garbage_timer,
+ (unsigned long) uart);
+ INIT_WORK(&uart->wakeup_work, omap_uart_wakeup_work);
if (uart->timeout)
mod_timer(&uart->timer, jiffies + uart->timeout);
omap_uart_smart_idle_enable(uart, 0);
@@ -503,15 +556,13 @@ static void omap_uart_idle_init(struct omap_uart_state *uart)
void omap_uart_enable_irqs(int enable)
{
- int ret;
struct omap_uart_state *uart;
list_for_each_entry(uart, &uart_list, node) {
if (enable)
- ret = request_irq(uart->p->irq, omap_uart_interrupt,
- IRQF_SHARED, "serial idle", (void *)uart);
+ enable_irq(uart->p->irq);
else
- free_irq(uart->p->irq, (void *)uart);
+ disable_irq(uart->p->irq);
}
}
--
1.7.0.2
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