[PATCH v6 0/5] mailbox: add Samsung Exynos driver

[PATCH v6 0/5] mailbox: add Samsung Exynos driver

[Tudor Ambarus]

The Samsung Exynos mailbox controller, used on Google GS101 SoC, has 16 flag
bits for hardware interrupt generation and a shared register for passing
mailbox messages. When the controller is used by the ACPM protocol the shared
register is ignored and the mailbox controller acts as a doorbell.
The controller just raises the interrupt to APM after the ACPM protocol has
written the message to SRAM.

Changes in v6:
- mailbox: add support for clients to request channels by arguments.
  Used by the ACPM interface where the channel identifiers are
  discovered at runtime. Passing them via DT would be redundant.
  Initial version sent on its own to gather feedback:
  - Link: https://lore.kernel.org/all/20241219-mbox_request_channel_by_args-v1-0-617a6910f842@linaro.org/
  - the patches differ from the initial version as they allow #mbox-cells = 0
- bindings: google,gs101-mbox: update description, make #mbox-cells
  const 0.
- mailbox: exynos-mailbox:
  - replace exynos_mbox_of_xlate with exynos_mbox_xlate, the channel
    identifiers are discovered at runtime and passed as
    'const struct mbox_xlate_args *sp'
  - in the xlate method, the first argument is the channel and the
    second the type, as channels can be configured either in DOORBELL or
    DATA modes. This becomes an example for when an exynos_mbox_of_xlate()
    method will be introduced.
  - make exynos_mbox_chan_index() inline and directly
    return chan - chan->mbox->chans;
- drop Krzysztof's and Peter's R-b tags from the google,gs101-mbox
  bindings and the Samsung Exynos mailbox driver as they were updated.
- add Krzysztof's and Peter's R-b tags to the MAINTAINERS patch
- Link to v5: https://lore.kernel.org/r/20241217-acpm-v4-upstream-mbox-v5-0-cd1d3951fe84@linaro.org

Changes in v5:
- fix dt-bindings by using the correct compatible name in the example
- drop redundand "bindings" from the dt-bindings patch subject
- rebase on top of v6.13-rc3
- Link to v4: https://lore.kernel.org/r/20241212-acpm-v4-upstream-mbox-v4-0-02f8de92cfaf@linaro.org

Changes in v4:
- rename bindings file to be based on compatible: google,gs101-acpm-mbox
- specify doorbell or data mode via '#mbox-cells' dt property. Update
  driver and introduce exynos_mbox_of_xlate() to parse the mode.
- s/samsung/Samsung/, s/exynos/Exynos/
- use writel instead of writel_relaxed
- remove stray of_match_ptr()
- Link to v3: https://lore.kernel.org/linux-arm-kernel/20241205174137.190545-1-tudor.ambarus@linaro.org/

Changes in v3:
- decouple the mailbox controller driver from the ACPM protocol driver
- address Krzysztof's review comments

v2:
https://lore.kernel.org/linux-arm-kernel/20241017163649.3007062-1-tudor.ambarus@linaro.org/

v1:
https://lore.kernel.org/linux-arm-kernel/20241004165301.1979527-1-tudor.ambarus@linaro.org/

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
---
Tudor Ambarus (5):
      dt-bindings: mailbox: allow #mbox-cells = <0>;
      dt-bindings: mailbox: add google,gs101-mbox
      mailbox: add support for clients to request channels by args
      mailbox: add Samsung Exynos driver
      MAINTAINERS: add entry for Samsung Exynos mailbox driver

 .../bindings/mailbox/google,gs101-mbox.yaml        |  70 +++++++++
 .../devicetree/bindings/mailbox/mailbox.txt        |   3 +-
 MAINTAINERS                                        |  10 ++
 drivers/mailbox/Kconfig                            |  11 ++
 drivers/mailbox/Makefile                           |   2 +
 drivers/mailbox/exynos-mailbox.c                   | 174 +++++++++++++++++++++
 drivers/mailbox/mailbox.c                          |  60 +++++++
 include/dt-bindings/mailbox/google,gs101.h         |  14 ++
 include/linux/mailbox.h                            |  17 ++
 include/linux/mailbox_client.h                     |   3 +
 include/linux/mailbox_controller.h                 |   4 +
 11 files changed, 366 insertions(+), 2 deletions(-)
---
base-commit: 78d4f34e2115b517bcbfe7ec0d018bbbb6f9b0b8
change-id: 20241212-acpm-v4-upstream-mbox-948714004b05

Best regards,
-- 
Tudor Ambarus <tudor.ambarus@linaro.org>

[PATCH v6 1/5] dt-bindings: mailbox: allow #mbox-cells = <0>;

[Tudor Ambarus]

There are mailbox clients that can discover the mailbox channel
identifiers at runtime. For such cases passing the channel
identifiers via DT is redundant.

The framework API will be supplied with mbox_request_channel_by_args().
It will allow clients to request a mailbox channel using the runtime
discovered channel identifiers.

Add support for referencing controllers solely by phandle.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
---
 Documentation/devicetree/bindings/mailbox/mailbox.txt | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/mailbox/mailbox.txt b/Documentation/devicetree/bindings/mailbox/mailbox.txt
index af8ecee2ac68..fc31a4a3b637 100644
--- a/Documentation/devicetree/bindings/mailbox/mailbox.txt
+++ b/Documentation/devicetree/bindings/mailbox/mailbox.txt
@@ -6,8 +6,7 @@ assign appropriate mailbox channel to client drivers.
 * Mailbox Controller
 
 Required property:
-- #mbox-cells: Must be at least 1. Number of cells in a mailbox
-		specifier.
+- #mbox-cells: Must be at least 0. Number of cells in a mailbox specifier.
 
 Example:
 	mailbox: mailbox {

-- 
2.47.1.613.gc27f4b7a9f-goog

Re: [PATCH v6 1/5] dt-bindings: mailbox: allow #mbox-cells = <0>;

[Krzysztof Kozlowski]

On Fri, Dec 20, 2024 at 01:49:56PM +0000, Tudor Ambarus wrote:
> There are mailbox clients that can discover the mailbox channel
> identifiers at runtime. For such cases passing the channel
> identifiers via DT is redundant.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof

[PATCH v6 2/5] dt-bindings: mailbox: add google,gs101-mbox

[Tudor Ambarus]

Add bindings for the Samsung Exynos Mailbox Controller.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
---
 .../bindings/mailbox/google,gs101-mbox.yaml        | 70 ++++++++++++++++++++++
 include/dt-bindings/mailbox/google,gs101.h         | 14 +++++
 2 files changed, 84 insertions(+)

diff --git a/Documentation/devicetree/bindings/mailbox/google,gs101-mbox.yaml b/Documentation/devicetree/bindings/mailbox/google,gs101-mbox.yaml
new file mode 100644
index 000000000000..a1fbc3b2b9de
--- /dev/null
+++ b/Documentation/devicetree/bindings/mailbox/google,gs101-mbox.yaml
@@ -0,0 +1,70 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+# Copyright 2024 Linaro Ltd.
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mailbox/google,gs101-mbox.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Samsung Exynos Mailbox Controller
+
+maintainers:
+  - Tudor Ambarus <tudor.ambarus@linaro.org>
+
+description: |
+  The Samsung Exynos mailbox controller, used on Google GS101 SoC, has 16 flag
+  bits for hardware interrupt generation and a shared register for passing
+  mailbox messages. When the controller is used by the ACPM protocol the shared
+  register is ignored and the mailbox controller acts as a doorbell.
+  The controller just raises the interrupt to the firmware after the
+  ACPM protocol has written the message to SRAM.
+
+properties:
+  compatible:
+    const: google,gs101-mbox
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    items:
+      - const: pclk
+
+  interrupts:
+    description: IRQ line for the RX mailbox.
+    maxItems: 1
+
+  '#mbox-cells':
+    const: 0
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - clock-names
+  - interrupts
+  - '#mbox-cells'
+
+additionalProperties: false
+
+examples:
+  # Doorbell mode.
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/clock/google,gs101.h>
+
+    soc {
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        ap2apm_mailbox: mailbox@17610000 {
+            compatible = "google,gs101-mbox";
+            reg = <0x17610000 0x1000>;
+            clocks = <&cmu_apm CLK_GOUT_APM_MAILBOX_APM_AP_PCLK>;
+            clock-names = "pclk";
+            interrupts = <GIC_SPI 73 IRQ_TYPE_LEVEL_HIGH 0>;
+            #mbox-cells = <0>;
+        };
+    };
diff --git a/include/dt-bindings/mailbox/google,gs101.h b/include/dt-bindings/mailbox/google,gs101.h
new file mode 100644
index 000000000000..7ff4fe669f9e
--- /dev/null
+++ b/include/dt-bindings/mailbox/google,gs101.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) */
+/*
+ * Copyright 2024 Linaro Ltd.
+ *
+ * This header provides constants for the defined mailbox channel types.
+ */
+
+#ifndef _DT_BINDINGS_MAILBOX_GOOGLE_GS101_H
+#define _DT_BINDINGS_MAILBOX_GOOGLE_GS101_H
+
+#define DOORBELL	0
+#define DATA		1
+
+#endif /* _DT_BINDINGS_MAILBOX_GOOGLE_GS101_H */

-- 
2.47.1.613.gc27f4b7a9f-goog

Re: [PATCH v6 2/5] dt-bindings: mailbox: add google,gs101-mbox

[Krzysztof Kozlowski]

On Fri, Dec 20, 2024 at 01:49:57PM +0000, Tudor Ambarus wrote:
> Add bindings for the Samsung Exynos Mailbox Controller.
> 
> Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
> ---
>  .../bindings/mailbox/google,gs101-mbox.yaml        | 70 ++++++++++++++++++++++
>  include/dt-bindings/mailbox/google,gs101.h         | 14 +++++

Drop the header, not used.

>  2 files changed, 84 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/mailbox/google,gs101-mbox.yaml b/Documentation/devicetree/bindings/mailbox/google,gs101-mbox.yaml
> new file mode 100644
> index 000000000000..a1fbc3b2b9de
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mailbox/google,gs101-mbox.yaml
> @@ -0,0 +1,70 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +# Copyright 2024 Linaro Ltd.
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/mailbox/google,gs101-mbox.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Samsung Exynos Mailbox Controller
> +
> +maintainers:
> +  - Tudor Ambarus <tudor.ambarus@linaro.org>
> +
> +description: |

Drop |

> +  The Samsung Exynos mailbox controller, used on Google GS101 SoC, has 16 flag
> +  bits for hardware interrupt generation and a shared register for passing
> +  mailbox messages. When the controller is used by the ACPM protocol the shared
> +  register is ignored and the mailbox controller acts as a doorbell.
> +  The controller just raises the interrupt to the firmware after the
> +  ACPM protocol has written the message to SRAM.
> +
> +properties:
> +  compatible:
> +    const: google,gs101-mbox
> +
> +  reg:
> +    maxItems: 1
> +
> +  clocks:
> +    maxItems: 1
> +
> +  clock-names:
> +    items:
> +      - const: pclk
> +
> +  interrupts:
> +    description: IRQ line for the RX mailbox.
> +    maxItems: 1
> +
> +  '#mbox-cells':
> +    const: 0
> +
> +required:
> +  - compatible
> +  - reg
> +  - clocks
> +  - clock-names
> +  - interrupts
> +  - '#mbox-cells'
> +
> +additionalProperties: false
> +
> +examples:
> +  # Doorbell mode.

Drop comment, not applicable now, I think.

Best regards,
Krzysztof

Re: [PATCH v6 2/5] dt-bindings: mailbox: add google,gs101-mbox

[Tudor Ambarus]

Hi, Krzysztof,

Will send a new version soon, replying to confirm that I address the
feedback received.

On 12/22/24 8:44 AM, Krzysztof Kozlowski wrote:
> On Fri, Dec 20, 2024 at 01:49:57PM +0000, Tudor Ambarus wrote:
>> Add bindings for the Samsung Exynos Mailbox Controller.
>>
>> Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
>> ---
>>  .../bindings/mailbox/google,gs101-mbox.yaml        | 70 ++++++++++++++++++++++
>>  include/dt-bindings/mailbox/google,gs101.h         | 14 +++++
> 
> Drop the header, not used.

not yet used in device tree indeed, will drop. I'll use driver
definitions for specifying channel types.
> 
>>  2 files changed, 84 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/mailbox/google,gs101-mbox.yaml b/Documentation/devicetree/bindings/mailbox/google,gs101-mbox.yaml
>> new file mode 100644
>> index 000000000000..a1fbc3b2b9de
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/mailbox/google,gs101-mbox.yaml
>> @@ -0,0 +1,70 @@

cut

>> +description: |
> 
> Drop |

okay

cut

>> +examples:
>> +  # Doorbell mode.
> 
> Drop comment, not applicable now, I think.

okay. Thanks!

[PATCH v6 3/5] mailbox: add support for clients to request channels by args

[Tudor Ambarus]

There are clients that can discover channel identifiers at runtime by
parsing a shared memory for example, as in the ACPM interface's case.

Supply a new framework API: mbox_request_channel_by_args().

It works by supplying the usual client pointer as the first argument,
the usual index of the mailbox specifier in the 'mboxes' property as
a second argument, and a pointer to a 'const struct mbox_xlate_args'
as a third. The newly introduced struct is modeled after
'struct of_phandle_args'. The API identifies the controller's device
node, and then calls that controller's xlate() method that will return
a pointer to a mbox_chan or a ERR_PTR. The binding between the channel
and the client is done in the typical way.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
---
 drivers/mailbox/mailbox.c          | 60 ++++++++++++++++++++++++++++++++++++++
 include/linux/mailbox.h            | 17 +++++++++++
 include/linux/mailbox_client.h     |  3 ++
 include/linux/mailbox_controller.h |  4 +++
 4 files changed, 84 insertions(+)

diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
index d3d26a2c9895..0eecffd5a2ad 100644
--- a/drivers/mailbox/mailbox.c
+++ b/drivers/mailbox/mailbox.c
@@ -467,6 +467,66 @@ struct mbox_chan *mbox_request_channel_byname(struct mbox_client *cl,
 }
 EXPORT_SYMBOL_GPL(mbox_request_channel_byname);
 
+/**
+ * mbox_request_channel_by_args - request a mailbox channel using client's
+ * channel identifiers.
+ * @cl: identity of the client requesting the channel.
+ * @index: index of mailbox specifier in 'mboxes' property.
+ * @spec: arguments that describe the channel.
+ *
+ * Used by clients that can discover the channel identifiers at runtime (by
+ * parsing a shared memory for example). The description of
+ * mbox_request_channel() applies here as well.
+ *
+ * Return: Pointer to the channel assigned to the client if successful.
+ *         ERR_PTR for request failure.
+ */
+struct mbox_chan *mbox_request_channel_by_args(struct mbox_client *cl,
+			int index, const struct mbox_xlate_args *mbox_spec)
+{
+	struct of_phandle_args of_args;
+	struct device *dev = cl->dev;
+	struct mbox_controller *mbox;
+	struct mbox_chan *chan;
+	int ret;
+
+	if (!dev || !dev->of_node) {
+		pr_debug("%s: No owner device node\n", __func__);
+		return ERR_PTR(-ENODEV);
+	}
+
+	if (of_parse_phandle_with_args(dev->of_node, "mboxes",
+				       "#mbox-cells", index, &of_args)) {
+		dev_dbg(dev, "%s: can't parse \"mboxes\" property\n", __func__);
+		return ERR_PTR(-ENODEV);
+	}
+
+	mutex_lock(&con_mutex);
+
+	chan = ERR_PTR(-EPROBE_DEFER);
+	list_for_each_entry(mbox, &mbox_cons, node)
+		if (mbox->dev->of_node == of_args.np && mbox->xlate) {
+			chan = mbox->xlate(mbox, mbox_spec);
+			if (!IS_ERR(chan))
+				break;
+		}
+
+	of_node_put(of_args.np);
+
+	if (IS_ERR(chan)) {
+		mutex_unlock(&con_mutex);
+		return chan;
+	}
+
+	ret = __mbox_bind_client(chan, cl);
+	if (ret)
+		chan = ERR_PTR(ret);
+
+	mutex_unlock(&con_mutex);
+	return chan;
+}
+EXPORT_SYMBOL_GPL(mbox_request_channel_by_args);
+
 /**
  * mbox_free_channel - The client relinquishes control of a mailbox
  *			channel by this call.
diff --git a/include/linux/mailbox.h b/include/linux/mailbox.h
new file mode 100644
index 000000000000..cef88c5ae49d
--- /dev/null
+++ b/include/linux/mailbox.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2024 Linaro Ltd.
+ */
+
+#ifndef __LINUX_MAILBOX_H
+#define __LINUX_MAILBOX_H
+
+#include <linux/types.h>
+
+#define MBOX_XLATE_MAX_ARGS 16
+struct mbox_xlate_args {
+	int args_count;
+	u32 args[MBOX_XLATE_MAX_ARGS];
+};
+
+#endif /* __LINUX_MAILBOX_H */
diff --git a/include/linux/mailbox_client.h b/include/linux/mailbox_client.h
index 734694912ef7..06e2721313ca 100644
--- a/include/linux/mailbox_client.h
+++ b/include/linux/mailbox_client.h
@@ -9,6 +9,7 @@
 
 #include <linux/of.h>
 #include <linux/device.h>
+#include <linux/mailbox.h>
 
 struct mbox_chan;
 
@@ -41,6 +42,8 @@ int mbox_bind_client(struct mbox_chan *chan, struct mbox_client *cl);
 struct mbox_chan *mbox_request_channel_byname(struct mbox_client *cl,
 					      const char *name);
 struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index);
+struct mbox_chan *mbox_request_channel_by_args(struct mbox_client *cl,
+			int index, const struct mbox_xlate_args *mbox_spec);
 int mbox_send_message(struct mbox_chan *chan, void *mssg);
 int mbox_flush(struct mbox_chan *chan, unsigned long timeout);
 void mbox_client_txdone(struct mbox_chan *chan, int r); /* atomic */
diff --git a/include/linux/mailbox_controller.h b/include/linux/mailbox_controller.h
index 6fee33cb52f5..dfddcf966f9f 100644
--- a/include/linux/mailbox_controller.h
+++ b/include/linux/mailbox_controller.h
@@ -8,6 +8,7 @@
 #include <linux/hrtimer.h>
 #include <linux/device.h>
 #include <linux/completion.h>
+#include <linux/mailbox.h>
 
 struct mbox_chan;
 
@@ -67,6 +68,7 @@ struct mbox_chan_ops {
  * @txpoll_period:	If 'txdone_poll' is in effect, the API polls for
  *			last TX's status after these many millisecs
  * @of_xlate:		Controller driver specific mapping of channel via DT
+ * @xlate:		Controller driver specific mapping of channel
  * @poll_hrt:		API private. hrtimer used to poll for TXDONE on all
  *			channels.
  * @node:		API private. To hook into list of controllers.
@@ -81,6 +83,8 @@ struct mbox_controller {
 	unsigned txpoll_period;
 	struct mbox_chan *(*of_xlate)(struct mbox_controller *mbox,
 				      const struct of_phandle_args *sp);
+	struct mbox_chan *(*xlate)(struct mbox_controller *mbox,
+				   const struct mbox_xlate_args *sp);
 	/* Internal to API */
 	struct hrtimer poll_hrt;
 	spinlock_t poll_hrt_lock;

-- 
2.47.1.613.gc27f4b7a9f-goog

Re: [PATCH v6 3/5] mailbox: add support for clients to request channels by args

[kernel test robot]

Hi Tudor,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 78d4f34e2115b517bcbfe7ec0d018bbbb6f9b0b8]

url:    https://github.com/intel-lab-lkp/linux/commits/Tudor-Ambarus/dt-bindings-mailbox-allow-mbox-cells-0/20241220-215938
base:   78d4f34e2115b517bcbfe7ec0d018bbbb6f9b0b8
patch link:    https://lore.kernel.org/r/20241220-acpm-v4-upstream-mbox-v6-3-a6942806e52a%40linaro.org
patch subject: [PATCH v6 3/5] mailbox: add support for clients to request channels by args
config: x86_64-buildonly-randconfig-001-20241221 (https://download.01.org/0day-ci/archive/20241221/202412211604.qPMHGnk0-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241221/202412211604.qPMHGnk0-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202412211604.qPMHGnk0-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/mailbox/mailbox.c:486: warning: Function parameter or struct member 'mbox_spec' not described in 'mbox_request_channel_by_args'
>> drivers/mailbox/mailbox.c:486: warning: Excess function parameter 'spec' description in 'mbox_request_channel_by_args'


vim +486 drivers/mailbox/mailbox.c

   469	
   470	/**
   471	 * mbox_request_channel_by_args - request a mailbox channel using client's
   472	 * channel identifiers.
   473	 * @cl: identity of the client requesting the channel.
   474	 * @index: index of mailbox specifier in 'mboxes' property.
   475	 * @spec: arguments that describe the channel.
   476	 *
   477	 * Used by clients that can discover the channel identifiers at runtime (by
   478	 * parsing a shared memory for example). The description of
   479	 * mbox_request_channel() applies here as well.
   480	 *
   481	 * Return: Pointer to the channel assigned to the client if successful.
   482	 *         ERR_PTR for request failure.
   483	 */
   484	struct mbox_chan *mbox_request_channel_by_args(struct mbox_client *cl,
   485				int index, const struct mbox_xlate_args *mbox_spec)
 > 486	{
   487		struct of_phandle_args of_args;
   488		struct device *dev = cl->dev;
   489		struct mbox_controller *mbox;
   490		struct mbox_chan *chan;
   491		int ret;
   492	
   493		if (!dev || !dev->of_node) {
   494			pr_debug("%s: No owner device node\n", __func__);
   495			return ERR_PTR(-ENODEV);
   496		}
   497	
   498		if (of_parse_phandle_with_args(dev->of_node, "mboxes",
   499					       "#mbox-cells", index, &of_args)) {
   500			dev_dbg(dev, "%s: can't parse \"mboxes\" property\n", __func__);
   501			return ERR_PTR(-ENODEV);
   502		}
   503	
   504		mutex_lock(&con_mutex);
   505	
   506		chan = ERR_PTR(-EPROBE_DEFER);
   507		list_for_each_entry(mbox, &mbox_cons, node)
   508			if (mbox->dev->of_node == of_args.np && mbox->xlate) {
   509				chan = mbox->xlate(mbox, mbox_spec);
   510				if (!IS_ERR(chan))
   511					break;
   512			}
   513	
   514		of_node_put(of_args.np);
   515	
   516		if (IS_ERR(chan)) {
   517			mutex_unlock(&con_mutex);
   518			return chan;
   519		}
   520	
   521		ret = __mbox_bind_client(chan, cl);
   522		if (ret)
   523			chan = ERR_PTR(ret);
   524	
   525		mutex_unlock(&con_mutex);
   526		return chan;
   527	}
   528	EXPORT_SYMBOL_GPL(mbox_request_channel_by_args);
   529	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

[PATCH v6 4/5] mailbox: add Samsung Exynos driver

[Tudor Ambarus]

The Samsung Exynos mailbox controller, used on Google GS101 SoC, has 16
flag bits for hardware interrupt generation and a shared register for
passing mailbox messages. When the controller is used by the
ACPM protocol the shared register is ignored and the mailbox controller
acts as a doorbell. The controller just raises the interrupt to APM
after the ACPM protocol has written the message to SRAM.

Add support for the Samsung Exynos mailbox controller.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
---
 drivers/mailbox/Kconfig          |  11 +++
 drivers/mailbox/Makefile         |   2 +
 drivers/mailbox/exynos-mailbox.c | 174 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 187 insertions(+)

diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index 8ecba7fb999e..44b808c4d97f 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -36,6 +36,17 @@ config ARM_MHU_V3
 	  that provides different means of transports: supported extensions
 	  will be discovered and possibly managed at probe-time.
 
+config EXYNOS_MBOX
+	tristate "Exynos Mailbox"
+	depends on ARCH_EXYNOS || COMPILE_TEST
+	help
+	  Say Y here if you want to build the Samsung Exynos Mailbox controller
+	  driver. The controller has 16 flag bits for hardware interrupt
+	  generation and a shared register for passing mailbox messages.
+	  When the controller is used by the ACPM protocol the shared register
+	  is ignored and the mailbox controller acts as a doorbell that raises
+	  the interrupt to the ACPM firmware.
+
 config IMX_MBOX
 	tristate "i.MX Mailbox"
 	depends on ARCH_MXC || COMPILE_TEST
diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
index 5f4f5b0ce2cc..86192b5c7c32 100644
--- a/drivers/mailbox/Makefile
+++ b/drivers/mailbox/Makefile
@@ -11,6 +11,8 @@ obj-$(CONFIG_ARM_MHU_V2)	+= arm_mhuv2.o
 
 obj-$(CONFIG_ARM_MHU_V3)	+= arm_mhuv3.o
 
+obj-$(CONFIG_EXYNOS_MBOX)	+= exynos-mailbox.o
+
 obj-$(CONFIG_IMX_MBOX)	+= imx-mailbox.o
 
 obj-$(CONFIG_ARMADA_37XX_RWTM_MBOX)	+= armada-37xx-rwtm-mailbox.o
diff --git a/drivers/mailbox/exynos-mailbox.c b/drivers/mailbox/exynos-mailbox.c
new file mode 100644
index 000000000000..07bbc6b442ef
--- /dev/null
+++ b/drivers/mailbox/exynos-mailbox.c
@@ -0,0 +1,174 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2020 Samsung Electronics Co., Ltd.
+ * Copyright 2020 Google LLC.
+ * Copyright 2024 Linaro Ltd.
+ */
+
+#include <dt-bindings/mailbox/google,gs101.h>
+#include <linux/bitops.h>
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/mailbox_controller.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#define EXYNOS_MBOX_MCUCTRL		0x0	/* Mailbox Control Register */
+#define EXYNOS_MBOX_INTCR0		0x24	/* Interrupt Clear Register 0 */
+#define EXYNOS_MBOX_INTMR0		0x28	/* Interrupt Mask Register 0 */
+#define EXYNOS_MBOX_INTSR0		0x2c	/* Interrupt Status Register 0 */
+#define EXYNOS_MBOX_INTMSR0		0x30	/* Interrupt Mask Status Register 0 */
+#define EXYNOS_MBOX_INTGR1		0x40	/* Interrupt Generation Register 1 */
+#define EXYNOS_MBOX_INTMR1		0x48	/* Interrupt Mask Register 1 */
+#define EXYNOS_MBOX_INTSR1		0x4c	/* Interrupt Status Register 1 */
+#define EXYNOS_MBOX_INTMSR1		0x50	/* Interrupt Mask Status Register 1 */
+
+#define EXYNOS_MBOX_INTMR0_MASK		GENMASK(15, 0)
+#define EXYNOS_MBOX_INTGR1_MASK		GENMASK(15, 0)
+
+#define EXYNOS_MBOX_CHAN_COUNT		HWEIGHT32(EXYNOS_MBOX_INTGR1_MASK)
+
+enum {
+	EXYNOS_MBOX_CELL_ID,
+	EXYNOS_MBOX_CELL_TYPE,
+	EXYNOS_MBOX_CELLS
+};
+
+#define EXYNOS_MBOX_CELL_TYPE_COUNT	2
+
+/**
+ * struct exynos_mbox - driver's private data.
+ * @regs:	mailbox registers base address.
+ * @mbox:	pointer to the mailbox controller.
+ * @dev:	pointer to the mailbox device.
+ * @pclk:	pointer to the mailbox peripheral clock.
+ */
+struct exynos_mbox {
+	void __iomem *regs;
+	struct mbox_controller *mbox;
+	struct device *dev;
+	struct clk *pclk;
+};
+
+static inline int exynos_mbox_chan_index(struct mbox_chan *chan)
+{
+	return chan - chan->mbox->chans;
+}
+
+static int exynos_mbox_send_data(struct mbox_chan *chan, void *data)
+{
+	struct exynos_mbox *exynos_mbox = dev_get_drvdata(chan->mbox->dev);
+	int index = exynos_mbox_chan_index(chan);
+
+	writel(BIT(index), exynos_mbox->regs + EXYNOS_MBOX_INTGR1);
+
+	return 0;
+}
+
+static const struct mbox_chan_ops exynos_mbox_chan_ops = {
+	.send_data = exynos_mbox_send_data,
+};
+
+static struct mbox_chan *exynos_mbox_xlate(struct mbox_controller *mbox,
+					   const struct mbox_xlate_args *sp)
+{
+	u32 id, type;
+
+	if (sp->args_count != EXYNOS_MBOX_CELLS) {
+		dev_err(mbox->dev, "Invalid argument count %d\n",
+			sp->args_count);
+		return ERR_PTR(-EINVAL);
+	}
+
+	id = sp->args[EXYNOS_MBOX_CELL_ID];
+	if (id >= mbox->num_chans) {
+		dev_err(mbox->dev, "Invalid channel ID %d\n", id);
+		return ERR_PTR(-EINVAL);
+	}
+
+	type = sp->args[EXYNOS_MBOX_CELL_TYPE];
+	if (type >= EXYNOS_MBOX_CELL_TYPE_COUNT) {
+		dev_err(mbox->dev, "Invalid channel type %d\n", type);
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (type == DATA) {
+		dev_err(mbox->dev, "DATA channel type [%d] not supported\n",
+			type);
+		return ERR_PTR(-EINVAL);
+	};
+
+	return &mbox->chans[id];
+}
+
+static const struct of_device_id exynos_mbox_match[] = {
+	{ .compatible = "google,gs101-mbox" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, exynos_mbox_match);
+
+static int exynos_mbox_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct exynos_mbox *exynos_mbox;
+	struct mbox_controller *mbox;
+	struct mbox_chan *chans;
+	int i;
+
+	exynos_mbox = devm_kzalloc(dev, sizeof(*exynos_mbox), GFP_KERNEL);
+	if (!exynos_mbox)
+		return -ENOMEM;
+
+	mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL);
+	if (!mbox)
+		return -ENOMEM;
+
+	chans = devm_kcalloc(dev, EXYNOS_MBOX_CHAN_COUNT, sizeof(*chans),
+			     GFP_KERNEL);
+	if (!chans)
+		return -ENOMEM;
+
+	exynos_mbox->regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(exynos_mbox->regs))
+		return PTR_ERR(exynos_mbox->regs);
+
+	exynos_mbox->pclk = devm_clk_get_enabled(dev, "pclk");
+	if (IS_ERR(exynos_mbox->pclk))
+		return dev_err_probe(dev, PTR_ERR(exynos_mbox->pclk),
+				     "Failed to enable clock.\n");
+
+	mbox->num_chans = EXYNOS_MBOX_CHAN_COUNT;
+	mbox->chans = chans;
+	mbox->dev = dev;
+	mbox->ops = &exynos_mbox_chan_ops;
+	mbox->xlate = exynos_mbox_xlate;
+
+	for (i = 0; i < EXYNOS_MBOX_CHAN_COUNT; i++)
+		chans[i].mbox = mbox;
+
+	exynos_mbox->dev = dev;
+	exynos_mbox->mbox = mbox;
+
+	platform_set_drvdata(pdev, exynos_mbox);
+
+	/* Mask out all interrupts. We support just polling channels for now. */
+	writel(EXYNOS_MBOX_INTMR0_MASK, exynos_mbox->regs + EXYNOS_MBOX_INTMR0);
+
+	return devm_mbox_controller_register(dev, mbox);
+}
+
+static struct platform_driver exynos_mbox_driver = {
+	.probe	= exynos_mbox_probe,
+	.driver	= {
+		.name = "exynos-acpm-mbox",
+		.of_match_table	= exynos_mbox_match,
+	},
+};
+module_platform_driver(exynos_mbox_driver);
+
+MODULE_AUTHOR("Tudor Ambarus <tudor.ambarus@linaro.org>");
+MODULE_DESCRIPTION("Samsung Exynos mailbox driver");
+MODULE_LICENSE("GPL");

-- 
2.47.1.613.gc27f4b7a9f-goog

[PATCH v6 5/5] MAINTAINERS: add entry for Samsung Exynos mailbox driver

[Tudor Ambarus]

Add entry for the Samsung Exynos mailbox driver.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Peter Griffin <peter.griffin@linaro.org>
---
 MAINTAINERS | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index baf0eeb9a355..6bef5fc5e4ee 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3023,6 +3023,7 @@ F:	drivers/*/*s3c24*
 F:	drivers/*/*s3c64xx*
 F:	drivers/*/*s5pv210*
 F:	drivers/clocksource/samsung_pwm_timer.c
+F:	drivers/mailbox/exynos-mailbox.c
 F:	drivers/memory/samsung/
 F:	drivers/pwm/pwm-samsung.c
 F:	drivers/soc/samsung/
@@ -20717,6 +20718,15 @@ F:	arch/arm64/boot/dts/exynos/exynos850*
 F:	drivers/clk/samsung/clk-exynos850.c
 F:	include/dt-bindings/clock/exynos850.h
 
+SAMSUNG EXYNOS MAILBOX DRIVER
+M:	Tudor Ambarus <tudor.ambarus@linaro.org>
+L:	linux-kernel@vger.kernel.org
+L:	linux-samsung-soc@vger.kernel.org
+S:	Supported
+F:	Documentation/devicetree/bindings/mailbox/google,gs101-mbox.yaml
+F:	drivers/mailbox/exynos-mailbox.c
+F:	include/dt-bindings/mailbox/google,gs101.h
+
 SAMSUNG EXYNOS PSEUDO RANDOM NUMBER GENERATOR (RNG) DRIVER
 M:	Krzysztof Kozlowski <krzk@kernel.org>
 L:	linux-crypto@vger.kernel.org

-- 
2.47.1.613.gc27f4b7a9f-goog