ARM: OMAP: convert I2C driver to PM QoS for MPU 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Convert the driver from the outdated omap_pm_set_max_mpu_wakeup_lat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.

Signed-off-by: Jean Pihet <j-pihet@ti.com>
Acked-by: Shubhrajyoti D <shubhrajyoti@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>

1 files changed, 18 insertions, 14 deletions

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index c78431a4970a..b6c6b95d4a07 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;
@@ -1097,7 +1103,6 @@ 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;
         }
 
@@ -1153,9 +1158,8 @@ 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 */