[PATCH v10 2/6] remoteproc: pru: Add APIs to get and put the PRU cores

[MD Danish Anwar]

From: Tero Kristo <t-kristo@xxxxxx>

Add two new APIs, pru_rproc_get() and pru_rproc_put(), to the PRU
driver to allow client drivers to acquire and release the remoteproc
device associated with a PRU core. The PRU cores are treated as
resources with only one client owning it at a time.

The pru_rproc_get() function returns the rproc handle corresponding
to a PRU core identified by the device tree "ti,prus" property under
the client node. The pru_rproc_put() is the complementary function
to pru_rproc_get().

Signed-off-by: Suman Anna <s-anna@xxxxxx>
Signed-off-by: Tero Kristo <t-kristo@xxxxxx>
Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@xxxxxxxxxx>
Signed-off-by: MD Danish Anwar <danishanwar@xxxxxx>
---
 drivers/remoteproc/pru_rproc.c | 126 ++++++++++++++++++++++++++++++++-
 include/linux/pruss.h          |  46 ++++++++++++
 2 files changed, 170 insertions(+), 2 deletions(-)
 create mode 100644 include/linux/pruss.h

diff --git a/drivers/remoteproc/pru_rproc.c b/drivers/remoteproc/pru_rproc.c
index 128bf9912f2c..b4498a505108 100644
--- a/drivers/remoteproc/pru_rproc.c
+++ b/drivers/remoteproc/pru_rproc.c
@@ -2,12 +2,14 @@
 /*
  * PRU-ICSS remoteproc driver for various TI SoCs
  *
- * Copyright (C) 2014-2020 Texas Instruments Incorporated - https://www.ti.com/
+ * Copyright (C) 2014-2022 Texas Instruments Incorporated - https://www.ti.com/
  *
  * Author(s):
  *	Suman Anna <s-anna@xxxxxx>
  *	Andrew F. Davis <afd@xxxxxx>
  *	Grzegorz Jaszczyk <grzegorz.jaszczyk@xxxxxxxxxx> for Texas Instruments
+ *	Puranjay Mohan <p-mohan@xxxxxx>
+ *	Md Danish Anwar <danishanwar@xxxxxx>
  */
 
 #include <linux/bitops.h>
@@ -16,6 +18,7 @@
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/of_irq.h>
+#include <linux/pruss.h>
 #include <linux/pruss_driver.h>
 #include <linux/remoteproc.h>
 
@@ -111,6 +114,8 @@ struct pru_private_data {
  * @rproc: remoteproc pointer for this PRU core
  * @data: PRU core specific data
  * @mem_regions: data for each of the PRU memory regions
+ * @client_np: client device node
+ * @lock: mutex to protect client usage
  * @fw_name: name of firmware image used during loading
  * @mapped_irq: virtual interrupt numbers of created fw specific mapping
  * @pru_interrupt_map: pointer to interrupt mapping description (firmware)
@@ -126,6 +131,8 @@ struct pru_rproc {
 	struct rproc *rproc;
 	const struct pru_private_data *data;
 	struct pruss_mem_region mem_regions[PRU_IOMEM_MAX];
+	struct device_node *client_np;
+	struct mutex lock;
 	const char *fw_name;
 	unsigned int *mapped_irq;
 	struct pru_irq_rsc *pru_interrupt_map;
@@ -146,6 +153,117 @@ void pru_control_write_reg(struct pru_rproc *pru, unsigned int reg, u32 val)
 	writel_relaxed(val, pru->mem_regions[PRU_IOMEM_CTRL].va + reg);
 }
 
+static struct rproc *__pru_rproc_get(struct device_node *np, int index)
+{
+	struct rproc *rproc;
+	phandle rproc_phandle;
+	int ret;
+
+	ret = of_property_read_u32_index(np, "ti,prus", index, &rproc_phandle);
+	if (ret)
+		return ERR_PTR(ret);
+
+	rproc = rproc_get_by_phandle(rproc_phandle);
+	if (!rproc) {
+		ret = -EPROBE_DEFER;
+		goto err_no_rproc_handle;
+	}
+
+	/* make sure it is PRU rproc */
+	if (!is_pru_rproc(rproc->dev.parent)) {
+		rproc_put(rproc);
+		return ERR_PTR(-ENODEV);
+	}
+
+	return rproc;
+
+err_no_rproc_handle:
+	rproc_put(rproc);
+	return ERR_PTR(ret);
+}
+
+/**
+ * pru_rproc_get() - get the PRU rproc instance from a device node
+ * @np: the user/client device node
+ * @index: index to use for the ti,prus property
+ *
+ * This function looks through a client device node's "ti,prus" property at
+ * index @index and returns the rproc handle for a valid PRU remote processor if
+ * found. The function allows only one user to own the PRU rproc resource at a
+ * time. Caller must call pru_rproc_put() when done with using the rproc, not
+ * required if the function returns a failure.
+ *
+ * Return: rproc handle on success, and an ERR_PTR on failure using one
+ * of the following error values
+ *    -ENODEV if device is not found
+ *    -EBUSY if PRU is already acquired by anyone
+ *    -EPROBE_DEFER is PRU device is not probed yet
+ */
+struct rproc *pru_rproc_get(struct device_node *np, int index)
+{
+	struct rproc *rproc;
+	struct pru_rproc *pru;
+	struct device *dev;
+	int ret;
+
+	rproc = __pru_rproc_get(np, index);
+	if (IS_ERR(rproc))
+		return rproc;
+
+	pru = rproc->priv;
+	dev = &rproc->dev;
+
+	mutex_lock(&pru->lock);
+
+	if (pru->client_np) {
+		mutex_unlock(&pru->lock);
+		put_device(dev);
+		ret = -EBUSY;
+		goto err_no_rproc_handle;
+	}
+
+	pru->client_np = np;
+
+	mutex_unlock(&pru->lock);
+
+	return rproc;
+
+err_no_rproc_handle:
+	rproc_put(rproc);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(pru_rproc_get);
+
+/**
+ * pru_rproc_put() - release the PRU rproc resource
+ * @rproc: the rproc resource to release
+ *
+ * Releases the PRU rproc resource and makes it available to other
+ * users.
+ */
+void pru_rproc_put(struct rproc *rproc)
+{
+	struct pru_rproc *pru;
+
+	if (IS_ERR_OR_NULL(rproc) || !is_pru_rproc(rproc->dev.parent))
+		return;
+
+	pru = rproc->priv;
+
+	mutex_lock(&pru->lock);
+
+	if (!pru->client_np) {
+		mutex_unlock(&pru->lock);
+		return;
+	}
+
+	pru->client_np = NULL;
+	mutex_unlock(&pru->lock);
+
+	rproc_put(rproc);
+}
+EXPORT_SYMBOL_GPL(pru_rproc_put);
+
 static inline u32 pru_debug_read_reg(struct pru_rproc *pru, unsigned int reg)
 {
 	return readl_relaxed(pru->mem_regions[PRU_IOMEM_DEBUG].va + reg);
@@ -816,6 +934,8 @@ static int pru_rproc_probe(struct platform_device *pdev)
 	pru->pruss = platform_get_drvdata(ppdev);
 	pru->rproc = rproc;
 	pru->fw_name = fw_name;
+	pru->client_np = NULL;
+	mutex_init(&pru->lock);
 
 	for (i = 0; i < ARRAY_SIZE(mem_names); i++) {
 		res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
@@ -904,7 +1024,7 @@ MODULE_DEVICE_TABLE(of, pru_rproc_match);
 
 static struct platform_driver pru_rproc_driver = {
 	.driver = {
-		.name   = "pru-rproc",
+		.name   = PRU_RPROC_DRVNAME,
 		.of_match_table = pru_rproc_match,
 		.suppress_bind_attrs = true,
 	},
@@ -916,5 +1036,7 @@ module_platform_driver(pru_rproc_driver);
 MODULE_AUTHOR("Suman Anna <s-anna@xxxxxx>");
 MODULE_AUTHOR("Andrew F. Davis <afd@xxxxxx>");
 MODULE_AUTHOR("Grzegorz Jaszczyk <grzegorz.jaszczyk@xxxxxxxxxx>");
+MODULE_AUTHOR("Puranjay Mohan <p-mohan@xxxxxx>");
+MODULE_AUTHOR("Md Danish Anwar <danishanwar@xxxxxx>");
 MODULE_DESCRIPTION("PRU-ICSS Remote Processor Driver");
 MODULE_LICENSE("GPL v2");
diff --git a/include/linux/pruss.h b/include/linux/pruss.h
new file mode 100644
index 000000000000..5c5d14b1249d
--- /dev/null
+++ b/include/linux/pruss.h
@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/**
+ * PRU-ICSS Subsystem user interfaces
+ *
+ * Copyright (C) 2015-2022 Texas Instruments Incorporated - http://www.ti.com
+ *	Suman Anna <s-anna@xxxxxx>
+ */
+
+#ifndef __LINUX_PRUSS_H
+#define __LINUX_PRUSS_H
+
+#include <linux/device.h>
+#include <linux/types.h>
+
+#define PRU_RPROC_DRVNAME "pru-rproc"
+
+struct device_node;
+
+#if IS_ENABLED(CONFIG_PRU_REMOTEPROC)
+
+struct rproc *pru_rproc_get(struct device_node *np, int index);
+void pru_rproc_put(struct rproc *rproc);
+
+#else
+
+static inline struct rproc *
+pru_rproc_get(struct device_node *np, int index)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+static inline void pru_rproc_put(struct rproc *rproc) { }
+
+#endif /* CONFIG_PRU_REMOTEPROC */
+
+static inline bool is_pru_rproc(struct device *dev)
+{
+	const char *drv_name = dev_driver_string(dev);
+
+	if (strncmp(drv_name, PRU_RPROC_DRVNAME, sizeof(PRU_RPROC_DRVNAME)))
+		return false;
+
+	return true;
+}
+
+#endif /* __LINUX_PRUSS_H */
-- 
2.25.1