IKXCLOCK-2142 i2c: omap: convert I2C driver to PM QoS for latency constraints

Convert the driver from the outdated omap_pm_set_max_mpu_wakeup_lat
API to the new PM QoS API.
Since the constraint is on the MPU subsystem, use the PM_QOS_CPU_DMA_LATENCY
class of PM QoS. The resulting MPU constraints are used by cpuidle to
decide the next power state of the MPU subsystem.

The I2C device latency timing is derived from the FIFO size and the
clock speed and so is applicable to all OMAP SoCs.

Based on: 671d9f5 OMAP: convert I2C driver to PM QoS for latency
constraints

Change-Id: Iea5ac78d89019ed6e8888a0d6489057186748bfa
Signed-off-by: Mohsan Habibi <mohsan@motorola.com>

1 files changed, 20 insertions, 14 deletions

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index e02f9e36a7b..86fff71a5db 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -43,6 +43,7 @@
 #include <linux/slab.h>
 #include <linux/i2c-omap.h>
 #include <linux/pm_runtime.h>
+#include <linux/pm_qos.h>
 #include <linux/pinctrl/consumer.h>
 
 /* I2C controller revisions */
@@ -188,9 +189,8 @@ struct omap_i2c_dev {
 	int			reg_shift;      /* bit shift for I2C register addresses */
 	struct completion	cmd_complete;
 	struct resource		*ioarea;
-	u32			latency;	/* maximum mpu wkup latency */
-	void			(*set_mpu_wkup_lat)(struct device *dev,
-						    long latency);
+	u32                     latency;        /* maximum mpu wkup latency */
+	struct pm_qos_request	pm_qos_request;
 	u32			speed;		/* Speed of bus in kHz */
 	u32			flags;
 	u16			cmd_err;
@@ -504,9 +504,7 @@ static void omap_i2c_resize_fifo(struct omap_i2c_dev *dev, u8 size, bool is_rx)
 		dev->b_hw = 1; /* Enable hardware fixes */
 
 	/* calculate wakeup latency constraint for MPU */
-	if (dev->set_mpu_wkup_lat != NULL)
-		dev->latency = (1000000 * dev->threshold) /
-			(1000 * dev->speed / 8);
+	dev->latency = (1000000 * dev->threshold) / (1000 * dev->speed >> 3);
 }
 
 /*
@@ -645,8 +643,13 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 	if (r < 0)
 		goto out;
 
-	if (dev->set_mpu_wkup_lat != NULL)
-		dev->set_mpu_wkup_lat(dev->dev, dev->latency);
+	/*
+	 * When waiting for completion of a i2c transfer, we need to
+	 * set a wake up latency constraint for the MPU. This is to
+	 * ensure quick enough wakeup from idle, when transfer
+	 * completes.
+	 */
+	pm_qos_update_request(&dev->pm_qos_request, dev->latency);
 
 	for (i = 0; i < num; i++) {
 		r = omap_i2c_xfer_msg(adap, &msgs[i], (i == (num - 1)));
@@ -659,8 +662,8 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 
 	omap_i2c_wait_for_bb(dev);
 
-	if (dev->set_mpu_wkup_lat != NULL)
-		dev->set_mpu_wkup_lat(dev->dev, -1);
+	pm_qos_update_request(&dev->pm_qos_request,
+			      PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE);
 
 out:
 	pm_runtime_mark_last_busy(dev->dev);
@@ -1120,7 +1123,6 @@ omap_i2c_probe(struct platform_device *pdev)
 	} else if (pdata != NULL) {
 		dev->speed = pdata->clkrate;
 		dev->flags = pdata->flags;
-		dev->set_mpu_wkup_lat = pdata->set_mpu_wkup_lat;
 	}
 
 	dev->pins = devm_pinctrl_get_select_default(&pdev->dev);
@@ -1151,6 +1153,9 @@ omap_i2c_probe(struct platform_device *pdev)
 	if (IS_ERR_VALUE(r))
 		goto err_free_mem;
 
+	pm_qos_add_request(&dev->pm_qos_request, PM_QOS_CPU_DMA_LATENCY,
+			   PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE);
+
 	/*
 	 * Read the Rev hi bit-[15:14] ie scheme this is 1 indicates ver2.
 	 * On omap1/3/2 Offset 4 is IE Reg the bit [15:14] is 0 at reset.
@@ -1206,9 +1211,8 @@ omap_i2c_probe(struct platform_device *pdev)
 			dev->b_hw = 1; /* Enable hardware fixes */
 
 		/* calculate wakeup latency constraint for MPU */
-		if (dev->set_mpu_wkup_lat != NULL)
-			dev->latency = (1000000 * dev->fifo_size) /
-				       (1000 * dev->speed / 8);
+		dev->latency = (1000000 * dev->fifo_size) /
+			       (1000 * dev->speed >> 3);
 	}
 
 	/* reset ASAP, clearing any IRQs */
@@ -1257,6 +1261,7 @@ omap_i2c_probe(struct platform_device *pdev)
 
 err_unuse_clocks:
 	omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, 0);
+	pm_qos_remove_request(&dev->pm_qos_request);
 	pm_runtime_put(dev->dev);
 	pm_runtime_disable(&pdev->dev);
 err_free_mem:
@@ -1275,6 +1280,7 @@ static int omap_i2c_remove(struct platform_device *pdev)
 		return ret;
 
 	omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, 0);
+	pm_qos_remove_request(&dev->pm_qos_request);
 	pm_runtime_put(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 	return 0;