[PATCH] ARM: OMAP: convert I2C driver to PM QoS for MPU latency constraints

[jean.pihet@newoldbits.com (Jean Pihet)]

Convert the driver from the outdated omap_pm_set_max_mpu_wakeup_lat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.

Signed-off-by: Jean Pihet <j-pihet@ti.com>
---
Rebased on git://git.pengutronix.de/git/wsa/linux.git, branch
i2c-embedded/for-next
---
 arch/arm/plat-omap/i2c.c      |   21 ---------------------
 drivers/i2c/busses/i2c-omap.c |   32 ++++++++++++++++++--------------
 include/linux/i2c-omap.h      |    1 -
 3 files changed, 18 insertions(+), 36 deletions(-)

diff --git a/arch/arm/plat-omap/i2c.c b/arch/arm/plat-omap/i2c.c
index 40bc06a..d29a2cc 100644
--- a/arch/arm/plat-omap/i2c.c
+++ b/arch/arm/plat-omap/i2c.c
@@ -26,7 +26,6 @@
 #include <linux/kernel.h>
 #include <linux/platform_device.h>
 #include <linux/i2c.h>
-#include <linux/i2c-omap.h>
 #include <linux/slab.h>
 #include <linux/err.h>
 #include <linux/clk.h>
@@ -34,7 +33,6 @@
 #include <mach/irqs.h>
 #include <plat/mux.h>
 #include <plat/i2c.h>
-#include <plat/omap-pm.h>
 #include <plat/omap_device.h>
 
 #define OMAP_I2C_SIZE		0x3f
@@ -130,16 +128,6 @@ static inline int omap1_i2c_add_bus(int bus_id)
 
 
 #ifdef CONFIG_ARCH_OMAP2PLUS
-/*
- * XXX This function is a temporary compatibility wrapper - only
- * needed until the I2C driver can be converted to call
- * omap_pm_set_max_dev_wakeup_lat() and handle a return code.
- */
-static void omap_pm_set_max_mpu_wakeup_lat_compat(struct device *dev, long t)
-{
-	omap_pm_set_max_mpu_wakeup_lat(dev, t);
-}
-
 static inline int omap2_i2c_add_bus(int bus_id)
 {
 	int l;
@@ -171,15 +159,6 @@ static inline int omap2_i2c_add_bus(int bus_id)
 	dev_attr = (struct omap_i2c_dev_attr *)oh->dev_attr;
 	pdata->flags = dev_attr->flags;
 
-	/*
-	 * 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.
-	 * Only omap3 has support for constraints
-	 */
-	if (cpu_is_omap34xx())
-		pdata->set_mpu_wkup_lat = omap_pm_set_max_mpu_wakeup_lat_compat;
 	pdev = omap_device_build(name, bus_id, oh, pdata,
 			sizeof(struct omap_i2c_bus_platform_data),
 			NULL, 0, 0);
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 0b02543..db31eae 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>
 
 /* I2C controller revisions */
 #define OMAP_I2C_OMAP1_REV_2		0x20
@@ -186,9 +187,8 @@ 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			dtrev;		/* extra revision from DT */
 	u32			flags;
@@ -494,9 +494,7 @@ 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 / 8);
 }
 
 /*
@@ -631,8 +629,16 @@ 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.
+	 */
+	if (dev->latency)
+		pm_qos_add_request(&dev->pm_qos_request,
+				   PM_QOS_CPU_DMA_LATENCY,
+				   dev->latency);
 
 	for (i = 0; i < num; i++) {
 		r = omap_i2c_xfer_msg(adap, &msgs[i], (i == (num - 1)));
@@ -640,8 +646,8 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 			break;
 	}
 
-	if (dev->set_mpu_wkup_lat != NULL)
-		dev->set_mpu_wkup_lat(dev->dev, -1);
+	if (dev->latency)
+		pm_qos_remove_request(&dev->pm_qos_request);
 
 	if (r == 0)
 		r = num;
@@ -1098,7 +1104,6 @@ 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->dtrev = pdata->rev;
 	}
 
@@ -1154,9 +1159,8 @@ 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 / 8);
 	}
 
 	/* reset ASAP, clearing any IRQs */
diff --git a/include/linux/i2c-omap.h b/include/linux/i2c-omap.h
index 92a0dc7..df804ba 100644
--- a/include/linux/i2c-omap.h
+++ b/include/linux/i2c-omap.h
@@ -34,7 +34,6 @@ struct omap_i2c_bus_platform_data {
 	u32		clkrate;
 	u32		rev;
 	u32		flags;
-	void		(*set_mpu_wkup_lat)(struct device *dev, long set);
 };
 
 #endif
-- 
1.7.7.6