spi/pl022: add support for pm_runtime autosuspend

Adds support for configuring the spi bus to use autosuspend for
runtime power management. This can reduce the latency in starting an
spi transfer by not suspending the device immediately following
completion of a transfer. If another transfer then takes place before
the autosuspend timeout, the call to resume the device can return
immediately rather than needing to risk sleeping in order to resume
the device.

Reviewed-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Chris Blair <chris.blair@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 18 insertions, 2 deletions

diff --git a/drivers/spi/spi-pl022.c b/drivers/spi/spi-pl022.c
index 82a929f916fd..13988a3024bb 100644
--- a/drivers/spi/spi-pl022.c
+++ b/drivers/spi/spi-pl022.c
@@ -1516,7 +1516,13 @@ static void pump_messages(struct work_struct *work)
                         /* nothing more to do - disable spi/ssp and power off */
                         writew((readw(SSP_CR1(pl022->virtbase)) &
                                 (~SSP_CR1_MASK_SSE)), SSP_CR1(pl022->virtbase));
-                        pm_runtime_put(&pl022->adev->dev);
+
+                        if (pl022->master_info->autosuspend_delay > 0) {
+                                pm_runtime_mark_last_busy(&pl022->adev->dev);
+                                pm_runtime_put_autosuspend(&pl022->adev->dev);
+                        } else {
+                                pm_runtime_put(&pl022->adev->dev);
+                        }
                 }
                 pl022->busy = false;
                 spin_unlock_irqrestore(&pl022->queue_lock, flags);
@@ -2247,7 +2253,17 @@ pl022_probe(struct amba_device *adev, const struct amba_id *id)
         dev_dbg(dev, "probe succeeded\n");
 
         /* let runtime pm put suspend */
-        pm_runtime_put(dev);
+        if (platform_info->autosuspend_delay > 0) {
+                dev_info(&adev->dev,
+                        "will use autosuspend for runtime pm, delay %dms\n",
+                        platform_info->autosuspend_delay);
+                pm_runtime_set_autosuspend_delay(dev,
+                        platform_info->autosuspend_delay);
+                pm_runtime_use_autosuspend(dev);
+                pm_runtime_put_autosuspend(dev);
+        } else {
+                pm_runtime_put(dev);
+        }
         return 0;
 
  err_spi_register: