[PATCH v7 2/3] ARM: bcm2835: Add the Raspberry Pi firmware driver
This gives us a function for making mailbox property channel requests
of the firmware, which is most notable in that it will let us get and
set clock rates.
Signed-off-by: Eric Anholt
Acked-by: Stephen Warren
---
v2: Drop power-domains stuff for now since we don't have the driver
core support to make it useful. Move to drivers/firmware/.
Capitalize the enums. De-global the firmware variable. Use the
firmware device to allocate our DMA buffer, so that the dma-ranges
DT property gets respected. Simplify the property tag transaction
interface even more, leaving a multi-tag interface still
available. For conciseness, rename "raspberrypi" to "rpi" on all
functions/enums/structs, and the "firmware" variable to "fw".
Print when the driver is probed successfully, since debugging
-EPROBE_DEFER handling is such a big part of bcm2835 development.
Drop -EBUSY mailbox handling since the mailbox core has been fixed
to return -EPROBE_DEFER in -next.
v3: Use kernel-doc style for big comments (from Noralf), drop stale
comment, use "dev" when freeing DMA as well.
v4: Move description comment into copyright comment, drop a dead
initialization of "ret", and print the firmware revision at probe
time.
v5: Rename the compatible to "raspberrypi,bcm2835-firmware", move
include to not say "property", add functions to get struct
rpi_firmware from the device_node and put when done, make property
functions take the rpi_firmware instead and never return
-EPROBE_DEFER, put the driver under its own RASPBERRYPI_FIRMWARE
Kconfig.
v6: Drop the try_module_get/module_put stuff, since all clients will
be referencing our symbols in order to call those functions,
anyway. Fix the kerneldoc comments for the changes in v5.
drivers/firmware/Kconfig | 7 +
drivers/firmware/Makefile | 1 +
drivers/firmware/raspberrypi.c | 260 +
include/soc/bcm2835/raspberrypi-firmware.h | 115 +
4 files changed, 383 insertions(+)
create mode 100644 drivers/firmware/raspberrypi.c
create mode 100644 include/soc/bcm2835/raspberrypi-firmware.h
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index 99c69a3..1faf511 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -136,6 +136,13 @@ config QCOM_SCM
bool
depends on ARM || ARM64
+config RASPBERRYPI_FIRMWARE
+ tristate "Raspberry Pi Firmware Driver"
+ depends on BCM2835_MBOX
+ help
+ This option enables support for communicating with the firmware on the
+ Raspberry Pi.
+
source "drivers/firmware/broadcom/Kconfig"
source "drivers/firmware/google/Kconfig"
source "drivers/firmware/efi/Kconfig"
diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index 4a4b897..95efc8f 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_FIRMWARE_MEMMAP) += memmap.o
obj-$(CONFIG_QCOM_SCM) += qcom_scm.o
obj-$(CONFIG_QCOM_SCM) += qcom_scm-32.o
CFLAGS_qcom_scm-32.o :=$(call as-instr,.arch_extension sec,-DREQUIRES_SEC=1)
+obj-$(CONFIG_RASPBERRYPI_FIRMWARE) += raspberrypi.o
obj-y += broadcom/
obj-$(CONFIG_GOOGLE_FIRMWARE) += google/
diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
new file mode 100644
index 000..dd506cd3
--- /dev/null
+++ b/drivers/firmware/raspberrypi.c
@@ -0,0 +1,260 @@
+/*
+ * Defines interfaces for interacting wtih the Raspberry Pi firmware's
+ * property channel.
+ *
+ * Copyright © 2015 Broadcom
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include
+#include
+#include
+#include
+#include
+#include
+
+#define MBOX_MSG(chan, data28) (((data28) & ~0xf) | ((chan) & 0xf))
+#define MBOX_CHAN(msg) ((msg) & 0xf)
+#define MBOX_DATA28(msg) ((msg) & ~0xf)
+#define MBOX_CHAN_PROPERTY 8
+
+struct rpi_firmware {
+ struct mbox_client cl;
+ struct mbox_chan *chan; /* The property channel. */
+ struct completion c;
+ u32 enabled;
+};
+
+static DEFINE_MUTEX(transaction_lock);
+
+static void response_callback(struct mbox_client *cl, void *msg)
+{
+ struct rpi_firmware *fw = container_of(cl, struct rpi_firmware, cl);
+ complete(>c);
+}
+
+/*
+ * Sends a request to the firmware through the BCM2835 mailbox driver,
+ * and synchronously waits for the reply.
+ */
+static int
+rpi_firmware_transaction(struct rpi_firmware *fw, u32 chan, u32 data)
+{
+ u32 message = MBOX_MSG(chan, data);
+ int ret;
+
+ WARN_ON(data & 0xf);
+
+ mutex_lock(_lock);
+ reinit_completion(>c);
+ ret = mbox_send_message(fw->chan, );
+ if (ret >= 0) {
+
[PATCH v7 2/3] ARM: bcm2835: Add the Raspberry Pi firmware driver
This gives us a function for making mailbox property channel requests
of the firmware, which is most notable in that it will let us get and
set clock rates.
Signed-off-by: Eric Anholt e...@anholt.net
Acked-by: Stephen Warren swar...@wwwdotorg.org
---
v2: Drop power-domains stuff for now since we don't have the driver
core support to make it useful. Move to drivers/firmware/.
Capitalize the enums. De-global the firmware variable. Use the
firmware device to allocate our DMA buffer, so that the dma-ranges
DT property gets respected. Simplify the property tag transaction
interface even more, leaving a multi-tag interface still
available. For conciseness, rename raspberrypi to rpi on all
functions/enums/structs, and the firmware variable to fw.
Print when the driver is probed successfully, since debugging
-EPROBE_DEFER handling is such a big part of bcm2835 development.
Drop -EBUSY mailbox handling since the mailbox core has been fixed
to return -EPROBE_DEFER in -next.
v3: Use kernel-doc style for big comments (from Noralf), drop stale
comment, use dev when freeing DMA as well.
v4: Move description comment into copyright comment, drop a dead
initialization of ret, and print the firmware revision at probe
time.
v5: Rename the compatible to raspberrypi,bcm2835-firmware, move
include to not say property, add functions to get struct
rpi_firmware from the device_node and put when done, make property
functions take the rpi_firmware instead and never return
-EPROBE_DEFER, put the driver under its own RASPBERRYPI_FIRMWARE
Kconfig.
v6: Drop the try_module_get/module_put stuff, since all clients will
be referencing our symbols in order to call those functions,
anyway. Fix the kerneldoc comments for the changes in v5.
drivers/firmware/Kconfig | 7 +
drivers/firmware/Makefile | 1 +
drivers/firmware/raspberrypi.c | 260 +
include/soc/bcm2835/raspberrypi-firmware.h | 115 +
4 files changed, 383 insertions(+)
create mode 100644 drivers/firmware/raspberrypi.c
create mode 100644 include/soc/bcm2835/raspberrypi-firmware.h
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index 99c69a3..1faf511 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -136,6 +136,13 @@ config QCOM_SCM
bool
depends on ARM || ARM64
+config RASPBERRYPI_FIRMWARE
+ tristate Raspberry Pi Firmware Driver
+ depends on BCM2835_MBOX
+ help
+ This option enables support for communicating with the firmware on the
+ Raspberry Pi.
+
source drivers/firmware/broadcom/Kconfig
source drivers/firmware/google/Kconfig
source drivers/firmware/efi/Kconfig
diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index 4a4b897..95efc8f 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_FIRMWARE_MEMMAP) += memmap.o
obj-$(CONFIG_QCOM_SCM) += qcom_scm.o
obj-$(CONFIG_QCOM_SCM) += qcom_scm-32.o
CFLAGS_qcom_scm-32.o :=$(call as-instr,.arch_extension sec,-DREQUIRES_SEC=1)
+obj-$(CONFIG_RASPBERRYPI_FIRMWARE) += raspberrypi.o
obj-y += broadcom/
obj-$(CONFIG_GOOGLE_FIRMWARE) += google/
diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
new file mode 100644
index 000..dd506cd3
--- /dev/null
+++ b/drivers/firmware/raspberrypi.c
@@ -0,0 +1,260 @@
+/*
+ * Defines interfaces for interacting wtih the Raspberry Pi firmware's
+ * property channel.
+ *
+ * Copyright © 2015 Broadcom
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include linux/dma-mapping.h
+#include linux/mailbox_client.h
+#include linux/module.h
+#include linux/of_platform.h
+#include linux/platform_device.h
+#include soc/bcm2835/raspberrypi-firmware.h
+
+#define MBOX_MSG(chan, data28) (((data28) ~0xf) | ((chan) 0xf))
+#define MBOX_CHAN(msg) ((msg) 0xf)
+#define MBOX_DATA28(msg) ((msg) ~0xf)
+#define MBOX_CHAN_PROPERTY 8
+
+struct rpi_firmware {
+ struct mbox_client cl;
+ struct mbox_chan *chan; /* The property channel. */
+ struct completion c;
+ u32 enabled;
+};
+
+static DEFINE_MUTEX(transaction_lock);
+
+static void response_callback(struct mbox_client *cl, void *msg)
+{
+ struct rpi_firmware *fw = container_of(cl, struct rpi_firmware, cl);
+ complete(fw-c);
+}
+
+/*
+ * Sends a request to the firmware through the BCM2835 mailbox driver,
+ * and synchronously waits for the reply.
+ */
+static int
+rpi_firmware_transaction(struct rpi_firmware *fw, u32 chan, u32 data)
+{
+ u32 message = MBOX_MSG(chan, data);
+ int ret;
+
+ WARN_ON(data 0xf);
+
+
Re: [PATCH v7 2/3] ARM: bcm2835: Add the Raspberry Pi firmware driver
On 06/05/2015 01:21 PM, Lee Jones wrote: On Thu, 04 Jun 2015, Stephen Warren wrote: On 06/04/2015 02:11 PM, Eric Anholt wrote: This gives us a function for making mailbox property channel requests of the firmware, which is most notable in that it will let us get and set clock rates. Acked-by: Stephen Warren Does anyone know how drivers/firmware/ is managed? I don't seem to be able to find a maintainer/supporter listed in MAINTAINERS. git log implies lots of different committers. I'd suggest send it through arm-soc with the rest of the series. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v7 2/3] ARM: bcm2835: Add the Raspberry Pi firmware driver
On Thu, 04 Jun 2015, Stephen Warren wrote: > On 06/04/2015 02:11 PM, Eric Anholt wrote: > > This gives us a function for making mailbox property channel requests > > of the firmware, which is most notable in that it will let us get and > > set clock rates. > > Acked-by: Stephen Warren Does anyone know how drivers/firmware/ is managed? I don't seem to be able to find a maintainer/supporter listed in MAINTAINERS. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v7 2/3] ARM: bcm2835: Add the Raspberry Pi firmware driver
On Thu, 04 Jun 2015, Stephen Warren wrote: On 06/04/2015 02:11 PM, Eric Anholt wrote: This gives us a function for making mailbox property channel requests of the firmware, which is most notable in that it will let us get and set clock rates. Acked-by: Stephen Warren swar...@wwwdotorg.org Does anyone know how drivers/firmware/ is managed? I don't seem to be able to find a maintainer/supporter listed in MAINTAINERS. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v7 2/3] ARM: bcm2835: Add the Raspberry Pi firmware driver
On 06/05/2015 01:21 PM, Lee Jones wrote: On Thu, 04 Jun 2015, Stephen Warren wrote: On 06/04/2015 02:11 PM, Eric Anholt wrote: This gives us a function for making mailbox property channel requests of the firmware, which is most notable in that it will let us get and set clock rates. Acked-by: Stephen Warren swar...@wwwdotorg.org Does anyone know how drivers/firmware/ is managed? I don't seem to be able to find a maintainer/supporter listed in MAINTAINERS. git log implies lots of different committers. I'd suggest send it through arm-soc with the rest of the series. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v7 2/3] ARM: bcm2835: Add the Raspberry Pi firmware driver
On 06/04/2015 02:11 PM, Eric Anholt wrote: > This gives us a function for making mailbox property channel requests > of the firmware, which is most notable in that it will let us get and > set clock rates. Acked-by: Stephen Warren -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH v7 2/3] ARM: bcm2835: Add the Raspberry Pi firmware driver
This gives us a function for making mailbox property channel requests
of the firmware, which is most notable in that it will let us get and
set clock rates.
Signed-off-by: Eric Anholt
---
v2: Drop power-domains stuff for now since we don't have the driver
core support to make it useful. Move to drivers/firmware/.
Capitalize the enums. De-global the firmware variable. Use the
firmware device to allocate our DMA buffer, so that the dma-ranges
DT property gets respected. Simplify the property tag transaction
interface even more, leaving a multi-tag interface still
available. For conciseness, rename "raspberrypi" to "rpi" on all
functions/enums/structs, and the "firmware" variable to "fw".
Print when the driver is probed successfully, since debugging
-EPROBE_DEFER handling is such a big part of bcm2835 development.
Drop -EBUSY mailbox handling since the mailbox core has been fixed
to return -EPROBE_DEFER in -next.
v3: Use kernel-doc style for big comments (from Noralf), drop stale
comment, use "dev" when freeing DMA as well.
v4: Move description comment into copyright comment, drop a dead
initialization of "ret", and print the firmware revision at probe
time.
v5: Rename the compatible to "raspberrypi,bcm2835-firmware", move
include to not say "property", add functions to get struct
rpi_firmware from the device_node and put when done, make property
functions take the rpi_firmware instead and never return
-EPROBE_DEFER, put the driver under its own RASPBERRYPI_FIRMWARE
Kconfig.
v6: Drop the try_module_get/module_put stuff, since all clients will
be referencing our symbols in order to call those functions,
anyway. Fix the kerneldoc comments for the changes in v5.
drivers/firmware/Kconfig | 7 +
drivers/firmware/Makefile | 1 +
drivers/firmware/raspberrypi.c | 260 +
include/soc/bcm2835/raspberrypi-firmware.h | 115 +
4 files changed, 383 insertions(+)
create mode 100644 drivers/firmware/raspberrypi.c
create mode 100644 include/soc/bcm2835/raspberrypi-firmware.h
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index 6517132..564aa5b 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -136,6 +136,13 @@ config QCOM_SCM
bool
depends on ARM || ARM64
+config RASPBERRYPI_FIRMWARE
+ tristate "Raspberry Pi Firmware Driver"
+ depends on BCM2835_MBOX
+ help
+ This option enables support for communicating with the firmware on the
+ Raspberry Pi.
+
source "drivers/firmware/google/Kconfig"
source "drivers/firmware/efi/Kconfig"
diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index 3fdd391..ee101a2 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_ISCSI_IBFT) += iscsi_ibft.o
obj-$(CONFIG_FIRMWARE_MEMMAP) += memmap.o
obj-$(CONFIG_QCOM_SCM) += qcom_scm.o
CFLAGS_qcom_scm.o :=$(call as-instr,.arch_extension sec,-DREQUIRES_SEC=1)
+obj-$(CONFIG_RASPBERRYPI_FIRMWARE) += raspberrypi.o
obj-$(CONFIG_GOOGLE_FIRMWARE) += google/
obj-$(CONFIG_EFI) += efi/
diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
new file mode 100644
index 000..dd506cd
--- /dev/null
+++ b/drivers/firmware/raspberrypi.c
@@ -0,0 +1,260 @@
+/*
+ * Defines interfaces for interacting wtih the Raspberry Pi firmware's
+ * property channel.
+ *
+ * Copyright © 2015 Broadcom
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include
+#include
+#include
+#include
+#include
+#include
+
+#define MBOX_MSG(chan, data28) (((data28) & ~0xf) | ((chan) & 0xf))
+#define MBOX_CHAN(msg) ((msg) & 0xf)
+#define MBOX_DATA28(msg) ((msg) & ~0xf)
+#define MBOX_CHAN_PROPERTY 8
+
+struct rpi_firmware {
+ struct mbox_client cl;
+ struct mbox_chan *chan; /* The property channel. */
+ struct completion c;
+ u32 enabled;
+};
+
+static DEFINE_MUTEX(transaction_lock);
+
+static void response_callback(struct mbox_client *cl, void *msg)
+{
+ struct rpi_firmware *fw = container_of(cl, struct rpi_firmware, cl);
+ complete(>c);
+}
+
+/*
+ * Sends a request to the firmware through the BCM2835 mailbox driver,
+ * and synchronously waits for the reply.
+ */
+static int
+rpi_firmware_transaction(struct rpi_firmware *fw, u32 chan, u32 data)
+{
+ u32 message = MBOX_MSG(chan, data);
+ int ret;
+
+ WARN_ON(data & 0xf);
+
+ mutex_lock(_lock);
+ reinit_completion(>c);
+ ret = mbox_send_message(fw->chan, );
+ if (ret >= 0) {
+ wait_for_completion(>c);
+ ret = 0;
+ } else {
+
Re: [PATCH v7 2/3] ARM: bcm2835: Add the Raspberry Pi firmware driver
On 06/04/2015 02:11 PM, Eric Anholt wrote: This gives us a function for making mailbox property channel requests of the firmware, which is most notable in that it will let us get and set clock rates. Acked-by: Stephen Warren swar...@wwwdotorg.org -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH v7 2/3] ARM: bcm2835: Add the Raspberry Pi firmware driver
This gives us a function for making mailbox property channel requests
of the firmware, which is most notable in that it will let us get and
set clock rates.
Signed-off-by: Eric Anholt e...@anholt.net
---
v2: Drop power-domains stuff for now since we don't have the driver
core support to make it useful. Move to drivers/firmware/.
Capitalize the enums. De-global the firmware variable. Use the
firmware device to allocate our DMA buffer, so that the dma-ranges
DT property gets respected. Simplify the property tag transaction
interface even more, leaving a multi-tag interface still
available. For conciseness, rename raspberrypi to rpi on all
functions/enums/structs, and the firmware variable to fw.
Print when the driver is probed successfully, since debugging
-EPROBE_DEFER handling is such a big part of bcm2835 development.
Drop -EBUSY mailbox handling since the mailbox core has been fixed
to return -EPROBE_DEFER in -next.
v3: Use kernel-doc style for big comments (from Noralf), drop stale
comment, use dev when freeing DMA as well.
v4: Move description comment into copyright comment, drop a dead
initialization of ret, and print the firmware revision at probe
time.
v5: Rename the compatible to raspberrypi,bcm2835-firmware, move
include to not say property, add functions to get struct
rpi_firmware from the device_node and put when done, make property
functions take the rpi_firmware instead and never return
-EPROBE_DEFER, put the driver under its own RASPBERRYPI_FIRMWARE
Kconfig.
v6: Drop the try_module_get/module_put stuff, since all clients will
be referencing our symbols in order to call those functions,
anyway. Fix the kerneldoc comments for the changes in v5.
drivers/firmware/Kconfig | 7 +
drivers/firmware/Makefile | 1 +
drivers/firmware/raspberrypi.c | 260 +
include/soc/bcm2835/raspberrypi-firmware.h | 115 +
4 files changed, 383 insertions(+)
create mode 100644 drivers/firmware/raspberrypi.c
create mode 100644 include/soc/bcm2835/raspberrypi-firmware.h
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index 6517132..564aa5b 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -136,6 +136,13 @@ config QCOM_SCM
bool
depends on ARM || ARM64
+config RASPBERRYPI_FIRMWARE
+ tristate Raspberry Pi Firmware Driver
+ depends on BCM2835_MBOX
+ help
+ This option enables support for communicating with the firmware on the
+ Raspberry Pi.
+
source drivers/firmware/google/Kconfig
source drivers/firmware/efi/Kconfig
diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index 3fdd391..ee101a2 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_ISCSI_IBFT) += iscsi_ibft.o
obj-$(CONFIG_FIRMWARE_MEMMAP) += memmap.o
obj-$(CONFIG_QCOM_SCM) += qcom_scm.o
CFLAGS_qcom_scm.o :=$(call as-instr,.arch_extension sec,-DREQUIRES_SEC=1)
+obj-$(CONFIG_RASPBERRYPI_FIRMWARE) += raspberrypi.o
obj-$(CONFIG_GOOGLE_FIRMWARE) += google/
obj-$(CONFIG_EFI) += efi/
diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
new file mode 100644
index 000..dd506cd
--- /dev/null
+++ b/drivers/firmware/raspberrypi.c
@@ -0,0 +1,260 @@
+/*
+ * Defines interfaces for interacting wtih the Raspberry Pi firmware's
+ * property channel.
+ *
+ * Copyright © 2015 Broadcom
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include linux/dma-mapping.h
+#include linux/mailbox_client.h
+#include linux/module.h
+#include linux/of_platform.h
+#include linux/platform_device.h
+#include soc/bcm2835/raspberrypi-firmware.h
+
+#define MBOX_MSG(chan, data28) (((data28) ~0xf) | ((chan) 0xf))
+#define MBOX_CHAN(msg) ((msg) 0xf)
+#define MBOX_DATA28(msg) ((msg) ~0xf)
+#define MBOX_CHAN_PROPERTY 8
+
+struct rpi_firmware {
+ struct mbox_client cl;
+ struct mbox_chan *chan; /* The property channel. */
+ struct completion c;
+ u32 enabled;
+};
+
+static DEFINE_MUTEX(transaction_lock);
+
+static void response_callback(struct mbox_client *cl, void *msg)
+{
+ struct rpi_firmware *fw = container_of(cl, struct rpi_firmware, cl);
+ complete(fw-c);
+}
+
+/*
+ * Sends a request to the firmware through the BCM2835 mailbox driver,
+ * and synchronously waits for the reply.
+ */
+static int
+rpi_firmware_transaction(struct rpi_firmware *fw, u32 chan, u32 data)
+{
+ u32 message = MBOX_MSG(chan, data);
+ int ret;
+
+ WARN_ON(data 0xf);
+
+ mutex_lock(transaction_lock);
+ reinit_completion(fw-c);
+ ret =
