remoteproc: add IOMMU hardware capability flag

The remoteproc framework currently relies on iommu_present() on
the bus the device is on, to perform MMU management. However, this
logic doesn't scale for multi-arch, especially for processors that
do not have an IOMMU. Replace this logic instead by using a h/w
capability flag for the presence of IOMMU in the rproc structure.

This issue is seen on OMAP platforms when trying to add a remoteproc
driver for a small Cortex M3 called the WkupM3 used for suspend /
resume management on TI AM335/AM437x SoCs. This processor does not
have an MMU. Same is the case with another processor subsystem
PRU-ICSS on AM335/AM437x. All these are platform devices, and the
current iommu_present check will not scale for the same kernel image
to support OMAP4/OMAP5 and AM335/AM437x.

The existing platform implementation drivers - OMAP remoteproc, STE
Modem remoteproc and DA8xx remoteproc, are updated as well to properly
configure the newly added rproc field.

Cc: Robert Tivy <rtivy@ti.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Suman Anna <s-anna@ti.com>
[small change in the commit title and in a single comment]
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>

4 files changed, 6 insertions, 13 deletions

diff --git a/drivers/remoteproc/da8xx_remoteproc.c b/drivers/remoteproc/da8xx_remoteproc.c
index 89fd057e5f1d..f8d6a0661c14 100644
--- a/drivers/remoteproc/da8xx_remoteproc.c
+++ b/drivers/remoteproc/da8xx_remoteproc.c
@@ -224,6 +224,7 @@ static int da8xx_rproc_probe(struct platform_device *pdev)
 
         drproc = rproc->priv;
         drproc->rproc = rproc;
+        rproc->has_iommu = false;
 
         platform_set_drvdata(pdev, rproc);
 
diff --git a/drivers/remoteproc/omap_remoteproc.c b/drivers/remoteproc/omap_remoteproc.c
index e85f30370760..b74368a91235 100644
--- a/drivers/remoteproc/omap_remoteproc.c
+++ b/drivers/remoteproc/omap_remoteproc.c
@@ -202,6 +202,8 @@ static int omap_rproc_probe(struct platform_device *pdev)
 
         oproc = rproc->priv;
         oproc->rproc = rproc;
+        /* All existing OMAP IPU and DSP processors have an MMU */
+        rproc->has_iommu = true;
 
         platform_set_drvdata(pdev, rproc);
 
diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index 3cd85a638afa..11cdb119e4f3 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -94,19 +94,8 @@ static int rproc_enable_iommu(struct rproc *rproc)
         struct device *dev = rproc->dev.parent;
         int ret;
 
-        /*
-         * We currently use iommu_present() to decide if an IOMMU
-         * setup is needed.
-         *
-         * This works for simple cases, but will easily fail with
-         * platforms that do have an IOMMU, but not for this specific
-         * rproc.
-         *
-         * This will be easily solved by introducing hw capabilities
-         * that will be set by the remoteproc driver.
-         */
-        if (!iommu_present(dev->bus)) {
-                dev_dbg(dev, "iommu not found\n");
+        if (!rproc->has_iommu) {
+                dev_dbg(dev, "iommu not present\n");
                 return 0;
         }
 
diff --git a/drivers/remoteproc/ste_modem_rproc.c b/drivers/remoteproc/ste_modem_rproc.c
index 16b7b7bd805b..dd193f35a1ff 100644
--- a/drivers/remoteproc/ste_modem_rproc.c
+++ b/drivers/remoteproc/ste_modem_rproc.c
@@ -289,6 +289,7 @@ static int sproc_probe(struct platform_device *pdev)
         sproc = rproc->priv;
         sproc->mdev = mdev;
         sproc->rproc = rproc;
+        rproc->has_iommu = false;
         mdev->drv_data = sproc;
 
         /* Provide callback functions to modem device */