gpu: host1x: Support module reset

Newer versions of Tegra come with early boot software that aggressively
puts various modules in reset. Add support to the host1x driver to take
the module out of reset on probe, and assert reset on removal.
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/host1x/dev.c

@@ -170,6 +170,13 @@ static int host1x_probe(struct platform_device *pdev)
 		return err;
 	}
 
+	host->rst = devm_reset_control_get(&pdev->dev, "host1x");
+	if (IS_ERR(host->rst)) {
+		err = PTR_ERR(host->clk);
+		dev_err(&pdev->dev, "failed to get reset: %d\n", err);
+		return err;
+	}
+
 	if (iommu_present(&platform_bus_type)) {
 		struct iommu_domain_geometry *geometry;
 		unsigned long order;
@@ -203,10 +210,16 @@ static int host1x_probe(struct platform_device *pdev)
 		goto fail_detach_device;
 	}
 
+	err = reset_control_deassert(host->rst);
+	if (err < 0) {
+		dev_err(&pdev->dev, "failed to deassert reset: %d\n", err);
+		goto fail_unprepare_disable;
+	}
+
 	err = host1x_syncpt_init(host);
 	if (err) {
 		dev_err(&pdev->dev, "failed to initialize syncpts\n");
-		goto fail_unprepare_disable;
+		goto fail_reset_assert;
 	}
 
 	err = host1x_intr_init(host, syncpt_irq);
@@ -227,6 +240,8 @@ static int host1x_probe(struct platform_device *pdev)
 	host1x_intr_deinit(host);
 fail_deinit_syncpt:
 	host1x_syncpt_deinit(host);
+fail_reset_assert:
+	reset_control_assert(host->rst);
 fail_unprepare_disable:
 	clk_disable_unprepare(host->clk);
 fail_detach_device:
@@ -248,6 +263,7 @@ static int host1x_remove(struct platform_device *pdev)
 	host1x_unregister(host);
 	host1x_intr_deinit(host);
 	host1x_syncpt_deinit(host);
+	reset_control_assert(host->rst);
 	clk_disable_unprepare(host->clk);
 
 	if (host->domain) {

drivers/gpu/host1x/dev.h

@@ -21,6 +21,7 @@
 #include <linux/iommu.h>
 #include <linux/iova.h>
 #include <linux/platform_device.h>
+#include <linux/reset.h>
 
 #include "cdma.h"
 #include "channel.h"
@@ -109,6 +110,7 @@ struct host1x {
 	struct host1x_syncpt_base *bases;
 	struct device *dev;
 	struct clk *clk;
+	struct reset_control *rst;
 
 	struct iommu_domain *domain;
 	struct iova_domain iova;