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Date: Fri, 8 Apr 2022 18:13:19 +0200
From: Javier Martinez Canillas <javierm@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Daniel Vetter <daniel.vetter@...ll.ch>,
dri-devel@...ts.freedesktop.org,
Thomas Zimmermann <tzimmermann@...e.de>,
Javier Martinez Canillas <javierm@...hat.com>,
Borislav Petkov <bp@...e.de>, Jonathan Corbet <corbet@....net>,
linux-doc@...r.kernel.org
Subject: [PATCH v2 2/5] firmware: sysfb: Add helpers to unregister a pdev and disable registration
These can be used by subsystems to unregister a platform device registered
by sysfb and also to disable future platform device registration in sysfb.
Suggested-by: Daniel Vetter <daniel.vetter@...ll.ch>
Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>
---
Changes in v2:
- Add kernel-doc comments and include in other_interfaces.rst (Daniel Vetter).
.../driver-api/firmware/other_interfaces.rst | 6 ++
drivers/firmware/sysfb.c | 73 +++++++++++++++++--
include/linux/sysfb.h | 19 +++++
3 files changed, 92 insertions(+), 6 deletions(-)
diff --git a/Documentation/driver-api/firmware/other_interfaces.rst b/Documentation/driver-api/firmware/other_interfaces.rst
index b81794e0cfbb..06ac89adaafb 100644
--- a/Documentation/driver-api/firmware/other_interfaces.rst
+++ b/Documentation/driver-api/firmware/other_interfaces.rst
@@ -13,6 +13,12 @@ EDD Interfaces
.. kernel-doc:: drivers/firmware/edd.c
:internal:
+Generic System Framebuffers Interface
+-------------------------------------
+
+.. kernel-doc:: drivers/firmware/sysfb.c
+ :export:
+
Intel Stratix10 SoC Service Layer
---------------------------------
Some features of the Intel Stratix10 SoC require a level of privilege
diff --git a/drivers/firmware/sysfb.c b/drivers/firmware/sysfb.c
index b032f40a92de..a50d2858ce4d 100644
--- a/drivers/firmware/sysfb.c
+++ b/drivers/firmware/sysfb.c
@@ -34,21 +34,78 @@
#include <linux/screen_info.h>
#include <linux/sysfb.h>
+static struct platform_device *pd;
+static DEFINE_MUTEX(load_lock);
+static bool disabled;
+
+/**
+ * sysfb_disable() - disable the Generic System Framebuffers support
+ *
+ * This disables the registration of system framebuffer devices that match the
+ * generic drivers that make use of the system framebuffer set up by firmware.
+ *
+ * Context: The function can sleep. A @load_lock mutex is acquired to serialize
+ * against sysfb_init(), that registers a system framebuffer device and
+ * sysfb_try_unregister(), that tries to unregister framebuffer devices.
+ */
+void sysfb_disable(void)
+{
+ mutex_lock(&load_lock);
+ disabled = true;
+ mutex_unlock(&load_lock);
+}
+EXPORT_SYMBOL_GPL(sysfb_disable);
+
+/**
+ * sysfb_try_unregister() - attempt to unregister a system framebuffer device
+ * @dev: device to unregister
+ *
+ * This tries to unregister a system framebuffer device if this was registered
+ * by the Generic System Framebuffers. The device will only be unregistered if
+ * it was registered by sysfb_init(), otherwise it will not be unregistered.
+ *
+ * Context: The function can sleep. a @load_lock mutex is acquired to serialize
+ * against sysfb_init(), that registers a simple framebuffer device and
+ * sysfb_disable(), that disables the Generic System Framebuffers support.
+ *
+ * Return:
+ * * true - the device was unregistered successfully
+ * * false - the device was not unregistered
+ */
+bool sysfb_try_unregister(struct device *dev)
+{
+ bool ret = true;
+
+ mutex_lock(&load_lock);
+ if (!pd || pd != to_platform_device(dev))
+ return false;
+
+ platform_device_unregister(to_platform_device(dev));
+ pd = NULL;
+ mutex_unlock(&load_lock);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(sysfb_try_unregister);
+
static __init int sysfb_init(void)
{
struct screen_info *si = &screen_info;
struct simplefb_platform_data mode;
- struct platform_device *pd;
const char *name;
bool compatible;
- int ret;
+ int ret = 0;
+
+ mutex_lock(&load_lock);
+ if (disabled)
+ goto unlock_mutex;
/* try to create a simple-framebuffer device */
compatible = sysfb_parse_mode(si, &mode);
if (compatible) {
pd = sysfb_create_simplefb(si, &mode);
if (!IS_ERR(pd))
- return 0;
+ goto unlock_mutex;
}
/* if the FB is incompatible, create a legacy framebuffer device */
@@ -60,8 +117,10 @@ static __init int sysfb_init(void)
name = "platform-framebuffer";
pd = platform_device_alloc(name, 0);
- if (!pd)
- return -ENOMEM;
+ if (!pd) {
+ ret = -ENOMEM;
+ goto unlock_mutex;
+ }
sysfb_apply_efi_quirks(pd);
@@ -73,9 +132,11 @@ static __init int sysfb_init(void)
if (ret)
goto err;
- return 0;
+ goto unlock_mutex;
err:
platform_device_put(pd);
+unlock_mutex:
+ mutex_unlock(&load_lock);
return ret;
}
diff --git a/include/linux/sysfb.h b/include/linux/sysfb.h
index 708152e9037b..e8c0313fac8f 100644
--- a/include/linux/sysfb.h
+++ b/include/linux/sysfb.h
@@ -55,6 +55,25 @@ struct efifb_dmi_info {
int flags;
};
+#ifdef CONFIG_SYSFB
+
+void sysfb_disable(void);
+bool sysfb_try_unregister(struct device *dev);
+
+#else /* CONFIG_SYSFB */
+
+static inline void sysfb_disable(void)
+{
+
+}
+
+static inline bool sysfb_try_unregister(struct device *dev)
+{
+ return false;
+}
+
+#endif /* CONFIG_SYSFB */
+
#ifdef CONFIG_EFI
extern struct efifb_dmi_info efifb_dmi_list[];
--
2.35.1
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