On 7/26/23 12:19, Simon Horman wrote:

On Tue, Jul 25, 2023 at 06:40:58PM +0200, Gatien Chevallier wrote:

quoted

Introduce a STM32 firewall framework that offers to firewall consumers
different firewall services such as the ability to check their access
rights against their firewall controller(s).

The STM32 firewall framework offers a generic API for STM32 firewall
controllers that is defined in their drivers to best fit the
specificity of each firewall.

There are various types of firewalls:
-Peripheral firewalls that filter accesses to peripherals
-Memory firewalls that filter accesses to memories or memory regions
-No type for undefined type of firewall

Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>

...

quoted

diff --git a/drivers/bus/stm32_firewall.c b/drivers/bus/stm32_firewall.c

...

quoted

+int stm32_firewall_populate_bus(struct stm32_firewall_controller *firewall_controller)
+{
+	struct stm32_firewall *firewalls;
+	struct device_node *child;
+	struct device *parent;
+	unsigned int i;
+	int len;
+	int err;
+
+	parent = firewall_controller->dev;
+
+	dev_dbg(parent, "Populating %s system bus\n", dev_name(firewall_controller->dev));
+
+	for_each_available_child_of_node(dev_of_node(parent), child) {
+		/* The feature-domains property is mandatory for firewall bus devices */
+		len = of_count_phandle_with_args(child, "feature-domains", "#feature-domain-cells");
+		if (len <= 0)

Coccinelle says that, due to breaking out of a
for_each_available_child_of_node() loop, a call to of_node_put()
is needed here

Hi Simon,

Thank you, I already sent a V3 correcting the patch ordering issue. I
will implement this for V4.

quoted

+			return -EINVAL;
+
+		firewalls = kcalloc(len, sizeof(*firewalls), GFP_KERNEL);
+		if (!firewalls)

And here.

ditto

quoted

+			return -ENOMEM;
+
+		err = stm32_firewall_get_firewall(child, firewalls, (unsigned int)len);
+		if (err) {
+			kfree(firewalls);

And here.

ditto

quoted

+			return err;
+		}
+
+		for (i = 0; i < len; i++) {
+			if (firewall_controller->grant_access(firewall_controller,
+							      firewalls[i].firewall_id)) {
+				/*
+				 * Peripheral access not allowed or not defined.
+				 * Mark the node as populated so platform bus won't probe it
+				 */
+				of_node_set_flag(child, OF_POPULATED);
+				dev_err(parent, "%s: Device driver will not be probed\n",
+					child->full_name);
+			}
+		}
+
+		kfree(firewalls);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(stm32_firewall_populate_bus);

quoted

diff --git a/drivers/bus/stm32_firewall.h b/drivers/bus/stm32_firewall.h

...

quoted

+/**
+ * struct stm32_firewall_controller - Information on firewall controller supplying services
+ *
+ * @name			Name of the firewall controller

kernel-doc complains that name and the other fields of
struct stm32_firewall_controller are not documented.
I believe this is because a ':' is needed after the name of
the parameter (in this case 'name').

  * @name:			Name of the firewall controller

Likewise, elsewhere.

I will implement it in V4, thank you.

quoted

+ * @dev				Device reference of the firewall controller
+ * @mmio			Base address of the firewall controller
+ * @entry			List entry of the firewall controller list
+ * @type			Type of firewall
+ * @max_entries			Number of entries covered by the firewall
+ * @grant_access		Callback used to grant access for a device access against a
+ *				firewall controller
+ * @release_access		Callback used to release resources taken by a device when access was
+ *				granted
+ * @grant_memory_range_access	Callback used to grant access for a device to a given memory region
+ */
+struct stm32_firewall_controller {
+	const char *name;
+	struct device *dev;
+	void __iomem *mmio;
+	struct list_head entry;
+	unsigned int type;
+	unsigned int max_entries;
+
+	int (*grant_access)(struct stm32_firewall_controller *ctrl, u32 id);
+	void (*release_access)(struct stm32_firewall_controller *ctrl, u32 id);
+	int (*grant_memory_range_access)(struct stm32_firewall_controller *ctrl, phys_addr_t paddr,
+					 size_t size);
+};
+
+/**
+ * int stm32_firewall_controller_register - Register a firewall controller to the STM32 firewall

kernel-doc seems unhappy about the presence of 'int' on this line.

  * stm32_firewall_controller_register - Register a firewall controller to the STM32 firewall

Likewise, elsewhere.

Yes, I will remove the type in V4.

quoted

+ *					    framework
+ * @firewall_controller		Firewall controller to register
+ *
+ * Returns 0 in case of success or -ENODEV if no controller was given.
+ */
+int stm32_firewall_controller_register(struct stm32_firewall_controller *firewall_controller);

...

quoted

diff --git a/include/linux/bus/stm32_firewall_device.h b/include/linux/bus/stm32_firewall_device.h
new file mode 100644
index 000000000000..9bdc4060154c
--- /dev/null
+++ b/include/linux/bus/stm32_firewall_device.h

@@ -0,0 +1,140 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2023, STMicroelectronics - All Rights Reserved
+ */
+
+#ifndef STM32_FIREWALL_DEVICE_H
+#define STM32_FIREWALL_DEVICE_H
+
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+#define STM32_FIREWALL_MAX_EXTRA_ARGS		5
+
+/* Opaque reference to stm32_firewall_controller */
+struct stm32_firewall_controller;
+
+/**
+ * stm32_firewall - Information on a device's firewall. Each device can have more than one firewall.

kernel-doc seems unhappy about the absence of struct on this line.

  * struct stm32_firewall - Information on a device's firewall. Each device can have more than one firewall.

Yes, I will add the struct in V4.

quoted

+ *
+ * @firewall_ctrl		Pointer referencing a firewall controller of the device. It is
+ *				opaque so a device cannot manipulate the controller's ops or access
+ *				the controller's data
+ * @extra_args			Extra arguments that are implementation dependent
+ * @entry			Name of the firewall entry
+ * @extra_args_size		Number of extra arguments
+ * @firewall_id			Firewall ID associated the device for this firewall controller
+ */
+struct stm32_firewall {
+	struct stm32_firewall_controller *firewall_ctrl;
+	u32 extra_args[STM32_FIREWALL_MAX_EXTRA_ARGS];
+	const char *entry;
+	size_t extra_args_size;
+	u32 firewall_id;
+};

...

Best regards,
Gatien