tty: serial: tegra: Add stub runtime power management

Add stub runtime_pm calls which go through the flow of enabling
and disabling but don't actually do anything with the device itself
as there's nothing useful we can do. This provides the core PM
framework with information about when the device is idle,
enabling chip wide power savings.

Bug 887359

Change-Id: I159f7798dbf141813ec1aa56ddb06cc8ca6595f4
Signed-off-by: Pradeep Goudagunta <pgoudagunta@nvidia.com>
Reviewed-on: http://git-master/r/159835
Reviewed-by: Rohan Somvanshi <rsomvanshi@nvidia.com>
Tested-by: Rohan Somvanshi <rsomvanshi@nvidia.com>

1 files changed, 12 insertions, 4 deletions

diff --git a/drivers/tty/serial/tegra_hsuart.c b/drivers/tty/serial/tegra_hsuart.c
index 4ece2a699337..51a9a0a69993 100644
--- a/drivers/tty/serial/tegra_hsuart.c
+++ b/drivers/tty/serial/tegra_hsuart.c
@@ -40,6 +40,7 @@
 #include <linux/workqueue.h>
 #include <linux/tegra_uart.h>
 #include <linux/tty_flip.h>
+#include <linux/pm_runtime.h>
 
 #include <mach/dma.h>
 #include <mach/clk.h>
@@ -758,6 +759,7 @@ static void tegra_uart_hw_deinit(struct tegra_uart_port *t)
 	spin_unlock_irqrestore(&t->uport.lock, flags);
 
 	clk_disable(t->clk);
+	pm_runtime_put_sync((&t->uport)->dev);
 }
 
 static void tegra_uart_free_rx_dma_buffer(struct tegra_uart_port *t)
@@ -792,6 +794,7 @@ static int tegra_uart_hw_init(struct tegra_uart_port *t)
 	t->ier_shadow = 0;
 	t->baud = 0;
 
+	pm_runtime_get_sync((&t->uport)->dev);
 	clk_enable(t->clk);
 
 	/* Reset the UART controller to clear all previous status.*/
@@ -1609,6 +1612,7 @@ static int __init tegra_uart_probe(struct platform_device *pdev)
 		}
 	}
 	tasklet_init(&t->tlet, tegra_uart_tasklet_action, (unsigned long) t);
+	pm_runtime_enable((&t->uport)->dev);
 
 	return ret;
 
@@ -1635,6 +1639,7 @@ static int __devexit tegra_uart_remove(struct platform_device *pdev)
 
 	u = &t->uport;
 	tasklet_kill(&t->tlet);
+	pm_runtime_disable(u->dev);
 	uart_remove_one_port(&tegra_uart_driver, u);
 
 	tegra_uart_free_rx_dma_buffer(t);
@@ -1661,6 +1666,7 @@ static int tegra_uart_suspend(struct platform_device *pdev, pm_message_t state)
 	/* enable clock before calling suspend so that controller
 	   register can be accessible */
 	if (t->uart_state == TEGRA_UART_CLOCK_OFF) {
+		pm_runtime_get_sync(u->dev);
 		clk_enable(t->clk);
 		t->uart_state = TEGRA_UART_OPENED;
 	}
@@ -1707,9 +1713,10 @@ void tegra_uart_request_clock_off(struct uart_port *uport)
 	}
 	spin_unlock_irqrestore(&uport->lock, flags);
 
-	if (is_clk_disable)
+	if (is_clk_disable) {
 		clk_disable(t->clk);
-
+		pm_runtime_put_sync(uport->dev);
+	}
 	return;
 }
 
@@ -1731,9 +1738,10 @@ void tegra_uart_request_clock_on(struct uart_port *uport)
 	}
 	spin_unlock_irqrestore(&uport->lock, flags);
 
-	if (is_clk_enable)
+	if (is_clk_enable) {
+		pm_runtime_get_sync(uport->dev);
 		clk_enable(t->clk);
-
+	}
 	return;
 }