1 files changed, 74 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/gk20a.c b/drivers/gpu/nvgpu/gk20a/gk20a.c
index a5b4fddc..b36beb52 100644
--- a/drivers/gpu/nvgpu/gk20a/gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/gk20a.c
@@ -42,6 +42,7 @@
 #include <linux/spinlock.h>
 #include <linux/tegra-powergate.h>
 #include <linux/tegra_pm_domains.h>
+#include <linux/clk/tegra.h>
 
 #include <linux/sched.h>
 #include <linux/input-cfboost.h>
@@ -1610,6 +1611,79 @@ void gk20a_reset(struct gk20a *g, u32 units)
         gk20a_enable(g, units);
 }
 
+/**
+ * gk20a_do_idle() - force the GPU to idle and railgate
+ *
+ * In success, this call MUST be balanced by caller with gk20a_do_unidle()
+ */
+int gk20a_do_idle(void)
+{
+        struct platform_device *pdev = to_platform_device(
+                bus_find_device_by_name(&platform_bus_type,
+                NULL, "gk20a.0"));
+        struct gk20a *g = get_gk20a(pdev);
+        struct gk20a_platform *platform = dev_get_drvdata(&pdev->dev);
+        struct fifo_gk20a *f = &g->fifo;
+        unsigned long timeout = jiffies + msecs_to_jiffies(200);
+        int chid, ref_cnt;
+
+        if (!platform->can_railgate)
+                return -ENOSYS;
+
+        /* acquire busy lock to block other busy() calls */
+        down_write(&g->busy_lock);
+
+        /* prevent suspend by incrementing usage counter */
+        pm_runtime_get_noresume(&pdev->dev);
+
+        /* check and wait until GPU is idle (with a timeout) */
+        pm_runtime_barrier(&pdev->dev);
+
+        for (chid = 0; chid < f->num_channels; chid++)
+                if (gk20a_wait_channel_idle(&f->channel[chid]))
+                        goto fail;
+
+        do {
+                mdelay(1);
+                ref_cnt = atomic_read(&pdev->dev.power.usage_count);
+        } while (ref_cnt != 1 && time_before(jiffies, timeout));
+
+        if (ref_cnt != 1)
+                goto fail;
+
+        /*
+         * if GPU is now idle, we will have only one ref count
+         * drop this ref which will rail gate the GPU
+         */
+        pm_runtime_put_sync(&pdev->dev);
+
+        /* add sufficient delay to allow GPU to rail gate */
+        mdelay(platform->railgate_delay + 100);
+
+        return 0;
+
+fail:
+        pm_runtime_put_noidle(&pdev->dev);
+        up_write(&g->busy_lock);
+        return -EBUSY;
+}
+
+/**
+ * gk20a_do_unidle() - unblock all the tasks blocked by gk20a_do_idle()
+ */
+int gk20a_do_unidle(void)
+{
+        struct platform_device *pdev = to_platform_device(
+                bus_find_device_by_name(&platform_bus_type,
+                NULL, "gk20a.0"));
+        struct gk20a *g = get_gk20a(pdev);
+
+        /* release the lock and open up all other busy() calls */
+        up_write(&g->busy_lock);
+
+        return 0;
+}
+
 int gk20a_init_gpu_characteristics(struct gk20a *g)
 {
         struct nvhost_gpu_characteristics *gpu = &g->gpu_characteristics;