[PATCH 09/17] soc: ti: pruss: add pruss_{request,release}_mem_region() API

[Roger Quadros <rogerq@ti.com>]

From: "Andrew F. Davis" <afd@ti.com>

Add two new API - pruss_request_mem_region() & pruss_release_mem_region(),
to the PRUSS platform driver to allow client drivers to acquire and release
the common memory resources present within a PRU-ICSS subsystem. This
allows the client drivers to directly manipulate the respective memories,
as per their design contract with the associated firmware.

Signed-off-by: Andrew F. Davis <afd@ti.com>
[s-anna@ti.com: rename functions, add error checking, comments]
Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Roger Quadros <rogerq@ti.com>
---
 drivers/soc/ti/pruss.c      | 81 +++++++++++++++++++++++++++++++++++++++++++++
 drivers/soc/ti/pruss.h      | 26 +++------------
 drivers/soc/ti/pruss_intc.c |  1 +
 include/linux/pruss.h       | 61 ++++++++++++++++++++++++++++++++++
 4 files changed, 147 insertions(+), 22 deletions(-)
 create mode 100644 include/linux/pruss.h

diff --git a/drivers/soc/ti/pruss.c b/drivers/soc/ti/pruss.c
index 0840b59..c2271c4 100644
--- a/drivers/soc/ti/pruss.c
+++ b/drivers/soc/ti/pruss.c
@@ -12,9 +12,89 @@
 #include <linux/io.h>
 #include <linux/of_address.h>
 #include <linux/of_device.h>
+#include <linux/pruss.h>
 
 #include "pruss.h"
 
+/**
+ * pruss_request_mem_region() - request a memory resource
+ * @pruss: the pruss instance
+ * @mem_id: the memory resource id
+ * @region: pointer to memory region structure to be filled in
+ *
+ * This function allows a client driver to request a memory resource,
+ * and if successful, will let the client driver own the particular
+ * memory region until released using the pruss_release_mem_region()
+ * API.
+ *
+ * Returns the memory region if requested resource is available, an
+ * error otherwise
+ */
+int pruss_request_mem_region(struct pruss *pruss, enum pruss_mem mem_id,
+			     struct pruss_mem_region *region)
+{
+	if (!pruss || !region)
+		return -EINVAL;
+
+	if (mem_id >= PRUSS_MEM_MAX)
+		return -EINVAL;
+
+	mutex_lock(&pruss->lock);
+
+	if (pruss->mem_in_use[mem_id]) {
+		mutex_unlock(&pruss->lock);
+		return -EBUSY;
+	}
+
+	*region = pruss->mem_regions[mem_id];
+	pruss->mem_in_use[mem_id] = region;
+
+	mutex_unlock(&pruss->lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pruss_request_mem_region);
+
+/**
+ * pruss_release_mem_region() - release a memory resource
+ * @pruss: the pruss instance
+ * @region: the memory region to release
+ *
+ * This function is the complimentary function to
+ * pruss_request_mem_region(), and allows the client drivers to
+ * release back a memory resource.
+ *
+ * Returns 0 on success, an error code otherwise
+ */
+int pruss_release_mem_region(struct pruss *pruss,
+			     struct pruss_mem_region *region)
+{
+	int id;
+
+	if (!pruss || !region)
+		return -EINVAL;
+
+	mutex_lock(&pruss->lock);
+
+	/* find out the memory region being released */
+	for (id = 0; id < PRUSS_MEM_MAX; id++) {
+		if (pruss->mem_in_use[id] == region)
+			break;
+	}
+
+	if (id == PRUSS_MEM_MAX) {
+		mutex_unlock(&pruss->lock);
+		return -EINVAL;
+	}
+
+	pruss->mem_in_use[id] = NULL;
+
+	mutex_unlock(&pruss->lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pruss_release_mem_region);
+
 static int pruss_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -41,6 +121,7 @@ static int pruss_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	pruss->dev = dev;
+	mutex_init(&pruss->lock);
 
 	np = of_get_child_by_name(node, "memories");
 	if (!np)
diff --git a/drivers/soc/ti/pruss.h b/drivers/soc/ti/pruss.h
index a5a0667..f8878c2 100644
--- a/drivers/soc/ti/pruss.h
+++ b/drivers/soc/ti/pruss.h
@@ -22,28 +22,6 @@
 #define MAX_PRU_HOST_INT	10
 
 /**
- * enum pruss_mem - PRUSS memory range identifiers
- */
-enum pruss_mem {
-	PRUSS_MEM_DRAM0 = 0,
-	PRUSS_MEM_DRAM1,
-	PRUSS_MEM_SHRD_RAM2,
-	PRUSS_MEM_MAX,
-};
-
-/**
- * struct pruss_mem_region - PRUSS memory region structure
- * @va: kernel virtual address of the PRUSS memory region
- * @pa: physical (bus) address of the PRUSS memory region
- * @size: size of the PRUSS memory region
- */
-struct pruss_mem_region {
-	void __iomem *va;
-	phys_addr_t pa;
-	size_t size;
-};
-
-/**
  * struct pruss_intc_config - INTC configuration info
  * @sysev_to_ch: system events to channel mapping information
  * @ch_to_host: interrupt channel to host interrupt information
@@ -57,12 +35,16 @@ struct pruss_intc_config {
  * struct pruss - PRUSS parent structure
  * @dev: pruss device pointer
  * @mem_regions: data for each of the PRUSS memory regions
+ * @mem_in_use: to indicate if memory resource is in use
  * @host_mask: indicate which HOST IRQs are enabled
+ * @lock: mutex to serialize access to resources
  */
 struct pruss {
 	struct device *dev;
 	struct pruss_mem_region mem_regions[PRUSS_MEM_MAX];
+	struct pruss_mem_region *mem_in_use[PRUSS_MEM_MAX];
 	u32 host_mask;
+	struct mutex lock; /* PRU resource lock */
 };
 
 int pruss_intc_configure(struct pruss *pruss,
diff --git a/drivers/soc/ti/pruss_intc.c b/drivers/soc/ti/pruss_intc.c
index dde054b..df6b83b 100644
--- a/drivers/soc/ti/pruss_intc.c
+++ b/drivers/soc/ti/pruss_intc.c
@@ -13,6 +13,7 @@
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
+#include <linux/pruss.h>
 
 #include "pruss.h"
 
diff --git a/include/linux/pruss.h b/include/linux/pruss.h
new file mode 100644
index 0000000..198ae25
--- /dev/null
+++ b/include/linux/pruss.h
@@ -0,0 +1,61 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/**
+ * PRU-ICSS Subsystem user interfaces
+ *
+ * Copyright (C) 2015-2018 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
+
+/**
+ * enum pruss_mem - PRUSS memory range identifiers
+ */
+enum pruss_mem {
+	PRUSS_MEM_DRAM0 = 0,
+	PRUSS_MEM_DRAM1,
+	PRUSS_MEM_SHRD_RAM2,
+	PRUSS_MEM_MAX,
+};
+
+/**
+ * struct pruss_mem_region - PRUSS memory region structure
+ * @va: kernel virtual address of the PRUSS memory region
+ * @pa: physical (bus) address of the PRUSS memory region
+ * @size: size of the PRUSS memory region
+ */
+struct pruss_mem_region {
+	void __iomem *va;
+	phys_addr_t pa;
+	size_t size;
+};
+
+struct pruss;
+
+#if IS_ENABLED(CONFIG_TI_PRUSS)
+
+int pruss_request_mem_region(struct pruss *pruss, enum pruss_mem mem_id,
+			     struct pruss_mem_region *region);
+int pruss_release_mem_region(struct pruss *pruss,
+			     struct pruss_mem_region *region);
+
+#else
+
+static inline int pruss_request_mem_region(struct pruss *pruss,
+					   enum pruss_mem mem_id,
+					   struct pruss_mem_region *region)
+{
+	return -ENOTSUPP;
+}
+
+static inline int pruss_release_mem_region(struct pruss *pruss,
+					   struct pruss_mem_region *region)
+{
+	return -ENOTSUPP;
+}
+
+#endif /* CONFIG_TI_PRUSS */
+
+#endif /* __LINUX_PRUSS_H */
-- 
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