OMAP3: Serial: Improved sleep logic

Commit Message

Tero Kristo Feb. 10, 2010, 4:28 p.m. UTC

None

Patch

diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
index 837b347..d7d96ba 100644
--- a/arch/arm/mach-omap2/serial.c
+++ b/arch/arm/mach-omap2/serial.c
@@ -23,12 +23,15 @@ 
 #include <linux/serial_reg.h>
 #include <linux/clk.h>
 #include <linux/io.h>
+#include <linux/delay.h>
 
 #include <plat/common.h>
 #include <plat/board.h>
 #include <plat/clock.h>
 #include <plat/control.h>
 
+#include <asm/div64.h>
+
 #include "prm.h"
 #include "pm.h"
 #include "prm-regbits-34xx.h"
@@ -36,13 +39,13 @@ 
 #define UART_OMAP_NO_EMPTY_FIFO_READ_IP_REV	0x52
 #define UART_OMAP_WER		0x17	/* Wake-up enable register */
 
-#define DEFAULT_TIMEOUT (5 * HZ)
+#define DEFAULT_TIMEOUT (5LL * NSEC_PER_SEC)
 
 struct omap_uart_state {
 	int num;
 	int can_sleep;
-	struct timer_list timer;
-	u32 timeout;
+	ktime_t expire_time;
+	u64 timeout;
 
 	void __iomem *wk_st;
 	void __iomem *wk_en;
@@ -231,6 +234,9 @@  static inline void omap_uart_enable_clocks(struct omap_uart_state *uart)
 	clk_enable(uart->fck);
 	uart->clocked = 1;
 	omap_uart_restore_context(uart);
+
+	/* Clear RX and TX fifos, as they contain garbage at this point */
+	serial_write_reg(uart->p, UART_FCR, 0xa7);
 }
 
 #ifdef CONFIG_PM
@@ -302,9 +308,7 @@  static void omap_uart_block_sleep(struct omap_uart_state *uart)
 	omap_uart_smart_idle_enable(uart, 0);
 	uart->can_sleep = 0;
 	if (uart->timeout)
-		mod_timer(&uart->timer, jiffies + uart->timeout);
-	else
-		del_timer(&uart->timer);
+		uart->expire_time = ktime_add_ns(ktime_get(), uart->timeout);
 }
 
 static void omap_uart_allow_sleep(struct omap_uart_state *uart)
@@ -317,25 +321,28 @@  static void omap_uart_allow_sleep(struct omap_uart_state *uart)
 	if (!uart->clocked)
 		return;
 
-	omap_uart_smart_idle_enable(uart, 1);
+	if (serial_read_reg(uart->p, UART_LSR) & UART_LSR_TEMT)
+		omap_uart_smart_idle_enable(uart, 1);
 	uart->can_sleep = 1;
-	del_timer(&uart->timer);
-}
-
-static void omap_uart_idle_timer(unsigned long data)
-{
-	struct omap_uart_state *uart = (struct omap_uart_state *)data;
-
-	omap_uart_allow_sleep(uart);
 }
 
 void omap_uart_prepare_idle(int num)
 {
 	struct omap_uart_state *uart;
+	ktime_t t;
 
 	list_for_each_entry(uart, &uart_list, node) {
+		if (num == uart->num && !uart->can_sleep) {
+			t = ktime_get();
+			if (t.tv64 > uart->expire_time.tv64)
+				uart->can_sleep = 1;
+		}
 		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);
+			else
+				omap_uart_smart_idle_enable(uart, 0);
 			return;
 		}
 	}
@@ -360,6 +367,7 @@  void omap_uart_resume_idle(int num)
 			/* Check for normal UART wakeup */
 			if (__raw_readl(uart->wk_st) & uart->wk_mask)
 				omap_uart_block_sleep(uart);
+
 			return;
 		}
 	}
@@ -407,8 +415,14 @@  int omap_uart_can_sleep(void)
 static irqreturn_t omap_uart_interrupt(int irq, void *dev_id)
 {
 	struct omap_uart_state *uart = dev_id;
+	u8 lsr;
 
-	omap_uart_block_sleep(uart);
+	lsr = serial_read_reg(uart->p, UART_LSR);
+	/* Check for receive interrupt */
+	if (lsr & UART_LSR_DR)
+		omap_uart_block_sleep(uart);
+	if (lsr & UART_LSR_TEMT && uart->can_sleep)
+		omap_uart_smart_idle_enable(uart, 1);
 
 	return IRQ_NONE;
 }
@@ -420,9 +434,9 @@  static void omap_uart_idle_init(struct omap_uart_state *uart)
 
 	uart->can_sleep = 0;
 	uart->timeout = DEFAULT_TIMEOUT;
-	setup_timer(&uart->timer, omap_uart_idle_timer,
-		    (unsigned long) uart);
-	mod_timer(&uart->timer, jiffies + uart->timeout);
+
+	uart->expire_time = ktime_add_ns(ktime_get(), uart->timeout);
+
 	omap_uart_smart_idle_enable(uart, 0);
 
 	if (cpu_is_omap34xx()) {
@@ -505,8 +519,12 @@  static ssize_t sleep_timeout_show(struct device *dev,
 					struct platform_device, dev);
 	struct omap_uart_state *uart = container_of(pdev,
 					struct omap_uart_state, pdev);
+	u64 val;
 
-	return sprintf(buf, "%u\n", uart->timeout / HZ);
+	val = uart->timeout;
+
+	do_div(val, NSEC_PER_SEC);
+	return sprintf(buf, "%llu\n", val);
 }
 
 static ssize_t sleep_timeout_store(struct device *dev,
@@ -524,10 +542,12 @@  static ssize_t sleep_timeout_store(struct device *dev,
 		return -EINVAL;
 	}
 
-	uart->timeout = value * HZ;
-	if (uart->timeout)
-		mod_timer(&uart->timer, jiffies + uart->timeout);
-	else
+	uart->timeout = (u64)value * NSEC_PER_SEC;
+	if (uart->timeout) {
+		uart->expire_time = ktime_get();
+		uart->expire_time =
+			ktime_add_ns(uart->expire_time, uart->timeout);
+	} else
 		/* A zero value means disable timeout feature */
 		omap_uart_block_sleep(uart);