[RFC 07/13] soc: ti: pruss: Add pruss_{request,release}_mem_region() API

[Puranjay Mohan <p-mohan@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.

Co-developed-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Andrew F. Davis <afd@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       | 77 ++++++++++++++++++++++++++++++++++++
 include/linux/pruss.h        | 39 ++++++++++++++++++
 include/linux/pruss_driver.h | 27 +++----------
 3 files changed, 121 insertions(+), 22 deletions(-)

diff --git a/drivers/soc/ti/pruss.c b/drivers/soc/ti/pruss.c
index 5ad62c35da5d..bda920662de2 100644
--- a/drivers/soc/ti/pruss.c
+++ b/drivers/soc/ti/pruss.c
@@ -88,6 +88,82 @@ void pruss_put(struct pruss *pruss)
 }
 EXPORT_SYMBOL_GPL(pruss_put);
 
+/**
+ * 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.
+ *
+ * Return: 0 if requested memory region is available (in such case pointer to
+ * memory region is returned via @region), an error otherwise
+ */
+int pruss_request_mem_region(struct pruss *pruss, enum pruss_mem mem_id,
+			     struct pruss_mem_region *region)
+{
+	if (!pruss || !region || 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.
+ *
+ * Return: 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 void pruss_of_free_clk_provider(void *data)
 {
 	struct device_node *clk_mux_np = data;
@@ -290,6 +366,7 @@ static int pruss_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	pruss->dev = dev;
+	mutex_init(&pruss->lock);
 
 	child = of_get_child_by_name(np, "memories");
 	if (!child) {
diff --git a/include/linux/pruss.h b/include/linux/pruss.h
index 23d556e0dd72..689ef243bcbc 100644
--- a/include/linux/pruss.h
+++ b/include/linux/pruss.h
@@ -39,6 +39,28 @@ enum pru_ctable_idx {
 	PRU_C31,
 };
 
+/*
+ * 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 device_node;
 struct rproc;
 struct pruss;
@@ -47,6 +69,10 @@ struct pruss;
 
 struct pruss *pruss_get(struct rproc *rproc);
 void pruss_put(struct pruss *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
 
@@ -57,6 +83,19 @@ static inline struct pruss *pruss_get(struct rproc *rproc)
 
 static inline void pruss_put(struct pruss *pruss) { }
 
+static inline int pruss_request_mem_region(struct pruss *pruss,
+					   enum pruss_mem mem_id,
+					   struct pruss_mem_region *region)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int pruss_release_mem_region(struct pruss *pruss,
+					   struct pruss_mem_region *region)
+{
+	return -EOPNOTSUPP;
+}
+
 #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 d054d2179d82..e2d5477225c6 100644
--- a/include/linux/pruss_driver.h
+++ b/include/linux/pruss_driver.h
@@ -9,37 +9,18 @@
 #ifndef _PRUSS_DRIVER_H_
 #define _PRUSS_DRIVER_H_
 
+#include <linux/mutex.h>
 #include <linux/pruss.h>
 #include <linux/types.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 - PRUSS parent structure
  * @dev: pruss device pointer
  * @cfg_base: base iomap for CFG region
  * @cfg_regmap: regmap for config region
  * @mem_regions: data for each of the PRUSS memory regions
+ * @mem_in_use: to indicate if memory resource is in use
+ * @lock: mutex to serialize access to resources
  * @core_clk_mux: clk handle for PRUSS CORE_CLK_MUX
  * @iep_clk_mux: clk handle for PRUSS IEP_CLK_MUX
  */
@@ -48,6 +29,8 @@ struct pruss {
 	void __iomem *cfg_base;
 	struct regmap *cfg_regmap;
 	struct pruss_mem_region mem_regions[PRUSS_MEM_MAX];
+	struct pruss_mem_region *mem_in_use[PRUSS_MEM_MAX];
+	struct mutex lock; /* PRU resource lock */
 	struct clk *core_clk_mux;
 	struct clk *iep_clk_mux;
 };
-- 
2.17.1