[PATCH 1/6] soc: ti: pruss: Add pruss_get()/put() API

[Grzegorz Jaszczyk]

From: Tero Kristo <t-kristo at 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 at ti.com>
Signed-off-by: Suman Anna <s-anna at ti.com>
Signed-off-by: Tero Kristo <t-kristo at ti.com>
Co-developed-by: Grzegorz Jaszczyk <grzegorz.jaszczyk at linaro.org>
Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk at linaro.org>
---
 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 5d6e7132a5c4..28eb6415cb95 100644
--- a/drivers/soc/ti/pruss.c
+++ b/drivers/soc/ti/pruss.c
@@ -6,6 +6,7 @@
  * Author(s):
  *	Suman Anna <s-anna at ti.com>
  *	Andrew F. Davis <afd at ti.com>
+ *	Tero Kristo <t-kristo at 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 903d0c0b75be..403951910515 100644
--- a/include/linux/pruss.h
+++ b/include/linux/pruss.h
@@ -4,12 +4,14 @@
  *
  * Copyright (C) 2015-2020 Texas Instruments Incorporated - http://www.ti.com
  *	Suman Anna <s-anna at ti.com>
+ *	Tero Kristo <t-kristo at 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(-ENOTSUPP);
+}
+
+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>
 
 /*
-- 
2.29.0