[PATCH v6 1/4] soc: ti: pruss: Add pruss_get()/put() API

[MD Danish Anwar]

From: Tero Kristo <t-kristo@xxxxxx>

Add two new get and put API, pruss_get() and pruss_put() to the
PRUSS platform driver to allow client drivers to request a handle
to a PRUSS device. This handle will be used by client drivers to
request various operations of the PRUSS platform driver through
additional API that will be added in the following patches.

The pruss_get() function returns the pruss handle corresponding
to a PRUSS device referenced by a PRU remoteproc instance. The
pruss_put() is the complimentary function to pruss_get().

Co-developed-by: Suman Anna <s-anna@xxxxxx>
Signed-off-by: Suman Anna <s-anna@xxxxxx>
Signed-off-by: Tero Kristo <t-kristo@xxxxxx>
Co-developed-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@xxxxxxxxxx>
Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@xxxxxxxxxx>
Signed-off-by: Puranjay Mohan <p-mohan@xxxxxx>
Reviewed-by: Roger Quadros <rogerq@xxxxxxxxxx>
Reviewed-by: Tony Lindgren <tony@xxxxxxxxxxx>
Signed-off-by: MD Danish Anwar <danishanwar@xxxxxx>
---
 drivers/remoteproc/pru_rproc.c                |  2 +-
 drivers/soc/ti/pruss.c                        | 64 ++++++++++++++++++-
 .../{pruss_driver.h => pruss_internal.h}      |  7 +-
 include/linux/remoteproc/pruss.h              | 19 ++++++
 4 files changed, 87 insertions(+), 5 deletions(-)
 rename include/linux/{pruss_driver.h => pruss_internal.h} (90%)

diff --git a/drivers/remoteproc/pru_rproc.c b/drivers/remoteproc/pru_rproc.c
index b76db7fa693d..4ddd5854d56e 100644
--- a/drivers/remoteproc/pru_rproc.c
+++ b/drivers/remoteproc/pru_rproc.c
@@ -19,7 +19,7 @@
 #include <linux/of_device.h>
 #include <linux/of_irq.h>
 #include <linux/remoteproc/pruss.h>
-#include <linux/pruss_driver.h>
+#include <linux/pruss_internal.h>
 #include <linux/remoteproc.h>
 
 #include "remoteproc_internal.h"
diff --git a/drivers/soc/ti/pruss.c b/drivers/soc/ti/pruss.c
index 6882c86b3ce5..28b77d715903 100644
--- a/drivers/soc/ti/pruss.c
+++ b/drivers/soc/ti/pruss.c
@@ -6,6 +6,7 @@
  * Author(s):
  *	Suman Anna <s-anna@xxxxxx>
  *	Andrew F. Davis <afd@xxxxxx>
+ *	Tero Kristo <t-kristo@xxxxxx>
  */
 
 #include <linux/clk-provider.h>
@@ -16,8 +17,9 @@
 #include <linux/of_address.h>
 #include <linux/of_device.h>
 #include <linux/pm_runtime.h>
-#include <linux/pruss_driver.h>
+#include <linux/pruss_internal.h>
 #include <linux/regmap.h>
+#include <linux/remoteproc.h>
 #include <linux/slab.h>
 
 /**
@@ -30,6 +32,66 @@ struct pruss_private_data {
 	bool has_core_mux_clock;
 };
 
+/**
+ * pruss_get() - get the pruss for a given PRU remoteproc
+ * @rproc: remoteproc handle of a PRU instance
+ *
+ * Finds the parent pruss device for a PRU given the @rproc handle of the
+ * PRU remote processor. This function increments the pruss device's refcount,
+ * so always use pruss_put() to decrement it back once pruss isn't needed
+ * anymore.
+ *
+ * This API doesn't check if @rproc is valid or not. It is expected the caller
+ * will have done a pru_rproc_get() on @rproc, before calling this API to make
+ * sure that @rproc is valid.
+ *
+ * Return: pruss handle on success, and an ERR_PTR on failure using one
+ * of the following error values
+ *    -EINVAL if invalid parameter
+ *    -ENODEV if PRU device or PRUSS device is not found
+ */
+struct pruss *pruss_get(struct rproc *rproc)
+{
+	struct pruss *pruss;
+	struct device *dev;
+	struct platform_device *ppdev;
+
+	if (IS_ERR_OR_NULL(rproc))
+		return ERR_PTR(-EINVAL);
+
+	dev = &rproc->dev;
+
+	/* make sure it is PRU rproc */
+	if (!dev->parent || !is_pru_rproc(dev->parent))
+		return ERR_PTR(-ENODEV);
+
+	ppdev = to_platform_device(dev->parent->parent);
+	pruss = platform_get_drvdata(ppdev);
+	if (!pruss)
+		return ERR_PTR(-ENODEV);
+
+	get_device(pruss->dev);
+
+	return pruss;
+}
+EXPORT_SYMBOL_GPL(pruss_get);
+
+/**
+ * pruss_put() - decrement pruss device's usecount
+ * @pruss: pruss handle
+ *
+ * Complimentary function for pruss_get(). Needs to be called
+ * after the PRUSS is used, and only if the pruss_get() succeeds.
+ */
+void pruss_put(struct pruss *pruss)
+{
+	if (IS_ERR_OR_NULL(pruss))
+		return;
+
+	put_device(pruss->dev);
+}
+EXPORT_SYMBOL_GPL(pruss_put);
+
 static void pruss_of_free_clk_provider(void *data)
 {
 	struct device_node *clk_mux_np = data;
diff --git a/include/linux/pruss_driver.h b/include/linux/pruss_internal.h
similarity index 90%
rename from include/linux/pruss_driver.h
rename to include/linux/pruss_internal.h
index ecfded30ed05..8f91cb164054 100644
--- a/include/linux/pruss_driver.h
+++ b/include/linux/pruss_internal.h
@@ -6,9 +6,10 @@
  *	Suman Anna <s-anna@xxxxxx>
  */
 
-#ifndef _PRUSS_DRIVER_H_
-#define _PRUSS_DRIVER_H_
+#ifndef _PRUSS_INTERNAL_H_
+#define _PRUSS_INTERNAL_H_
 
+#include <linux/remoteproc/pruss.h>
 #include <linux/types.h>
 
 /*
@@ -51,4 +52,4 @@ struct pruss {
 	struct clk *iep_clk_mux;
 };
 
-#endif	/* _PRUSS_DRIVER_H_ */
+#endif	/* _PRUSS_INTERNAL_H_ */
diff --git a/include/linux/remoteproc/pruss.h b/include/linux/remoteproc/pruss.h
index 039b50d58df2..93a98cac7829 100644
--- a/include/linux/remoteproc/pruss.h
+++ b/include/linux/remoteproc/pruss.h
@@ -4,12 +4,14 @@
  *
  * Copyright (C) 2015-2022 Texas Instruments Incorporated - http://www.ti.com
  *	Suman Anna <s-anna@xxxxxx>
+ *	Tero Kristo <t-kristo@xxxxxx>
  */
 
 #ifndef __LINUX_PRUSS_H
 #define __LINUX_PRUSS_H
 
 #include <linux/device.h>
+#include <linux/err.h>
 #include <linux/types.h>
 
 #define PRU_RPROC_DRVNAME "pru-rproc"
@@ -44,6 +46,23 @@ enum pru_ctable_idx {
 
 struct device_node;
 struct rproc;
+struct pruss;
+
+#if IS_ENABLED(CONFIG_TI_PRUSS)
+
+struct pruss *pruss_get(struct rproc *rproc);
+void pruss_put(struct pruss *pruss);
+
+#else
+
+static inline struct pruss *pruss_get(struct rproc *rproc)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+static inline void pruss_put(struct pruss *pruss) { }
+
+#endif /* CONFIG_TI_PRUSS */
 
 #if IS_ENABLED(CONFIG_PRU_REMOTEPROC)
 
-- 
2.25.1