cg2900: Use PM QoS for CG2900 UART

This patch adds usage of PM QoS in the CG2900 UART driver.
This is to assure that data throughput is not lowered due to
CPU going to sleep too often during data transfer.

ST-Ericsson ID: 361013
ST-Ericcson FOSS-OUT-ID: Trivial
ST-Ericsson Linux next: 361013

Change-Id: Ib79dee9bd95817d459acd477715d95d7aade06a7
Signed-off-by: Par-Gunnar Hjalmdahl <par-gunnar.p.hjalmdahl@stericsson.com>
Reviewed-on: http://gerrit.lud.stericsson.com/gerrit/33109
Reviewed-by: Lukasz RYMANOWSKI <lukasz.rymanowski@stericsson.com>
Reviewed-by: Jonas ABERG <jonas.aberg@stericsson.com>
Reviewed-by: Ulrik LAUREN <ulrik.lauren@stericsson.com>
Tested-by: Ulrik LAUREN <ulrik.lauren@stericsson.com>
Reviewed-by: Hemant GUPTA <hemant.gupta@stericsson.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/drivers/staging/cg2900/bluetooth/cg2900_uart.c b/drivers/staging/cg2900/bluetooth/cg2900_uart.c
index b5d67dce40e..d766e11207c 100644
--- a/drivers/staging/cg2900/bluetooth/cg2900_uart.c
+++ b/drivers/staging/cg2900/bluetooth/cg2900_uart.c
@@ -23,6 +23,7 @@
 #include <linux/mutex.h>
 #include <linux/platform_device.h>
 #include <linux/pm.h>
+#include <linux/pm_qos_params.h>
 #include <linux/poll.h>
 #include <linux/sched.h>
 #include <linux/skbuff.h>
@@ -58,6 +59,9 @@
 #define UART_RESP_TIMEOUT	1000
 #define UART_RESUME_TIMEOUT	20
 
+/* Max latency in microseconds for PM QoS to achieve max throughput */
+#define CG2900_PM_QOS_LATENCY	30
+
 /* Number of bytes to reserve at start of sk_buffer when receiving packet */
 #define RX_SKB_RESERVE		8
 /* Max size of received packet (not including reserved bytes) */
@@ -285,6 +289,8 @@ struct uart_delayed_work_struct {
  * @chip_dev:		Chip device for current UART transport.
  * @cts_irq:		CTS interrupt for this UART.
  * @cts_gpio:		CTS GPIO for this UART.
+ * @suspend_blocked:	True if suspend operation is blocked in the framework.
+ * @pm_qos_latency:	PM QoS structure.
  */
 struct uart_info {
 	enum uart_rx_state		rx_state;
@@ -312,6 +318,8 @@ struct uart_info {
 	struct cg2900_chip_dev		chip_dev;
 	int				cts_irq;
 	int				cts_gpio;
+	bool				suspend_blocked;
+	struct pm_qos_request_list	pm_qos_latency;
 };
 
 /* Module parameters */
@@ -395,6 +403,9 @@ static void handle_cts_irq(struct work_struct *work)
 		container_of(work, struct uart_work_struct, work);
 	struct uart_info *uart_info = (struct uart_info *)current_work->data;
 
+	pm_qos_update_request(&uart_info->pm_qos_latency,
+			      CG2900_PM_QOS_LATENCY);
+
 	spin_lock_bh(&(uart_info->transmission_lock));
 	/* Mark that there is an ongoing transfer. */
 	uart_info->rx_in_progress = true;
@@ -592,6 +603,12 @@ static void wake_up_chip(struct uart_info *uart_info)
 	if (CHIP_POWERED_DOWN == uart_info->sleep_state)
 		goto finished;
 
+	if (!uart_info->suspend_blocked) {
+		uart_info->suspend_blocked = true;
+		pm_qos_update_request(&uart_info->pm_qos_latency,
+				      CG2900_PM_QOS_LATENCY);
+	}
+
 	/*
 	 * This function indicates data is transmitted.
 	 * Therefore see to that the chip is awake.
@@ -708,6 +725,11 @@ static void set_chip_sleep_mode(struct work_struct *work)
 
 		dev_dbg(MAIN_DEV, "New sleep_state: CHIP_ASLEEP\n");
 		uart_info->sleep_state = CHIP_ASLEEP;
+		if (uart_info->suspend_blocked) {
+			uart_info->suspend_blocked = false;
+			pm_qos_update_request(&uart_info->pm_qos_latency,
+					      PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE);
+		}
 		break;
 	case CHIP_AWAKE:
 		chars_in_buffer = hci_uart_chars_in_buffer(uart_info->hu);
@@ -1352,6 +1374,11 @@ static void uart_set_chip_power(struct cg2900_chip_dev *dev, bool chip_on)
 	}
 
 	if (chip_on) {
+		if (!uart_info->suspend_blocked) {
+			uart_info->suspend_blocked = true;
+			pm_qos_update_request(&uart_info->pm_qos_latency,
+					      CG2900_PM_QOS_LATENCY);
+		}
 		if (uart_info->sleep_state != CHIP_POWERED_DOWN) {
 			dev_err(MAIN_DEV, "Chip is already powered up (%d)\n",
 				uart_info->sleep_state);
@@ -1388,6 +1415,12 @@ static void uart_set_chip_power(struct cg2900_chip_dev *dev, bool chip_on)
 			break;
 		}
 
+		if (uart_info->suspend_blocked) {
+			uart_info->suspend_blocked = false;
+			pm_qos_update_request(&uart_info->pm_qos_latency,
+					      PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE);
+		}
+
 		if (pf_data->disable_chip) {
 			pf_data->disable_chip(dev);
 			dev_dbg(MAIN_DEV,
@@ -1950,6 +1983,9 @@ static int __devinit cg2900_uart_probe(struct platform_device *pdev)
 	uart_info->chip_dev.dev = &pdev->dev;
 	uart_info->chip_dev.t_data = uart_info;
 
+	pm_qos_add_request(&uart_info->pm_qos_latency, PM_QOS_CPU_DMA_LATENCY,
+			   PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE);
+
 	resource = platform_get_resource_byname(pdev, IORESOURCE_IRQ,
 						"cts_irq");
 	if (!resource) {
@@ -2045,6 +2081,7 @@ static int __devexit cg2900_uart_remove(struct platform_device *pdev)
 	if (uart_info->hu)
 		hci_uart_unregister_proto(uart_info->hu->proto);
 
+	pm_qos_remove_request(&uart_info->pm_qos_latency);
 	destroy_workqueue(uart_info->wq);
 
 	dev_info(MAIN_DEV, "CG2900 UART removed\n");