[RFC 06/13] soc: ti: pruss: Add pruss_get()/put() API

[Puranjay Mohan <p-mohan@ti.com>]

From: Tero Kristo <t-kristo@ti.com>

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@ti.com>
Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Tero Kristo <t-kristo@ti.com>
Co-developed-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@linaro.org>
Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@linaro.org>
Signed-off-by: Puranjay Mohan <p-mohan@ti.com>
---
 drivers/soc/ti/pruss.c       | 58 ++++++++++++++++++++++++++++++++++++
 include/linux/pruss.h        | 19 ++++++++++++
 include/linux/pruss_driver.h |  1 +
 3 files changed, 78 insertions(+)

diff --git a/drivers/soc/ti/pruss.c b/drivers/soc/ti/pruss.c
index b36779309e49..5ad62c35da5d 100644
--- a/drivers/soc/ti/pruss.c
+++ b/drivers/soc/ti/pruss.c
@@ -6,6 +6,7 @@
  * Author(s):
  *	Suman Anna <s-anna@ti.com>
  *	Andrew F. Davis <afd@ti.com>
+ *	Tero Kristo <t-kristo@ti.com>
  */
 
 #include <linux/clk-provider.h>
@@ -18,6 +19,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/pruss_driver.h>
 #include <linux/regmap.h>
+#include <linux/remoteproc.h>
 #include <linux/slab.h>
 
 /**
@@ -30,6 +32,62 @@ 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.
+ *
+ * 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.h b/include/linux/pruss.h
index d830e20056c7..23d556e0dd72 100644
--- a/include/linux/pruss.h
+++ b/include/linux/pruss.h
@@ -4,12 +4,14 @@
  *
  * Copyright (C) 2015-2022 Texas Instruments Incorporated - http://www.ti.com
  *	Suman Anna <s-anna@ti.com>
+ *	Tero Kristo <t-kristo@ti.com>
  */
 
 #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"
@@ -39,6 +41,23 @@ 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)
 
diff --git a/include/linux/pruss_driver.h b/include/linux/pruss_driver.h
index ecfded30ed05..d054d2179d82 100644
--- a/include/linux/pruss_driver.h
+++ b/include/linux/pruss_driver.h
@@ -9,6 +9,7 @@
 #ifndef _PRUSS_DRIVER_H_
 #define _PRUSS_DRIVER_H_
 
+#include <linux/pruss.h>
 #include <linux/types.h>
 
 /*
-- 
2.17.1


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