[PATCH v6 0/2] ASPEED: Add mailbox driver for AST2700 series

[PATCH v6 0/2] ASPEED: Add mailbox driver for AST2700 series

[Jammy Huang]

Add mailbox controller driver for AST27XX SoCs, which provides
independent tx/rx mailbox between different processors. There are 4
channels for each tx/rx mailbox and each channel has an 32-byte FIFO.

 v6 changes:
  - Update document
     1. Update description to preserve paragraphs.
     2. Update for property, reg.
     3. Add reg-names.
     4. Add 'Reviewed-by' from Krok.
  - Update driver
     1. Use devm_platform_ioremap_resource_byname since we add reg-names now.
     2. Update error code for ch not enabled. 
 
 v5 changes:
  - Update document
     1. Separate reg from 1 to 2. 1st is tx controller; 2nd is rx.
     2. Remove 'Reviewed-by' since the patch has changed.
  - Update driver, no functional changes.
     1. Update since there is 2 reg base now.
     2. Refine reg definitions
     3. Add spinlock to protect registers
     4. Use bool as return value for ast2700_mbox_tx_done
     5. Rename variable from drv_data to dev_data.

 v4 changes:
  - Update driver, no functional changes.
     1. Remove unused variable, rx_buff, in struct ast2700_mbox.
     2. Remove unneeded cast on device_get_match_data.
     3. Remove the usage of writel/readl_relaxed.
     4. Improve readability.
 v3 changes:
  - Correct document
     1. Use 32-bit addressing in dts example property, reg.
 v2 changes:
  - Update document
     1. Correct error in dts example.
     2. Drop description for mbox-cell per suggestion previously.

Jammy Huang (2):
  dt-bindings: mailbox: Add ASPEED AST2700 series SoC
  mailbox: aspeed: add mailbox driver for AST27XX series SoC

 .../mailbox/aspeed,ast2700-mailbox.yaml       |  68 +++++
 drivers/mailbox/Kconfig                       |   8 +
 drivers/mailbox/Makefile                      |   2 +
 drivers/mailbox/ast2700-mailbox.c             | 240 ++++++++++++++++++
 4 files changed, 318 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mailbox/aspeed,ast2700-mailbox.yaml
 create mode 100644 drivers/mailbox/ast2700-mailbox.c


base-commit: ec7714e4947909190ffb3041a03311a975350fe0
-- 
2.25.1

[PATCH v6 1/2] dt-bindings: mailbox: Add ASPEED AST2700 series SoC

[Jammy Huang]

Introduce the mailbox module for AST27XX series SoC, which is responsible
for interchanging messages between asymmetric processors.

Signed-off-by: Jammy Huang <jammy_huang@aspeedtech.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
---
 .../mailbox/aspeed,ast2700-mailbox.yaml       | 68 +++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mailbox/aspeed,ast2700-mailbox.yaml

diff --git a/Documentation/devicetree/bindings/mailbox/aspeed,ast2700-mailbox.yaml b/Documentation/devicetree/bindings/mailbox/aspeed,ast2700-mailbox.yaml
new file mode 100644
index 000000000000..600e2d63fccd
--- /dev/null
+++ b/Documentation/devicetree/bindings/mailbox/aspeed,ast2700-mailbox.yaml
@@ -0,0 +1,68 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mailbox/aspeed,ast2700-mailbox.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ASPEED AST2700 mailbox controller
+
+maintainers:
+  - Jammy Huang <jammy_huang@aspeedtech.com>
+
+description: >
+  ASPEED AST2700 has multiple processors that need to communicate with each
+  other. The mailbox controller provides a way for these processors to send
+  messages to each other. It is a hardware-based inter-processor communication
+  mechanism that allows processors to send and receive messages through
+  dedicated channels.
+
+  The mailbox's tx/rx are independent, meaning that one processor can send a
+  message while another processor is receiving a message simultaneously.
+  There are 4 channels available for both tx and rx operations. Each channel
+  has a FIFO buffer that can hold messages of a fixed size (32 bytes in this
+  case).
+
+  The mailbox controller also supports interrupt generation, allowing
+  processors to notify each other when a message is available or when an event
+  occurs.
+
+properties:
+  compatible:
+    const: aspeed,ast2700-mailbox
+
+  reg:
+    items:
+      - description: TX control register
+      - description: RX control register
+
+  reg-names:
+    items:
+      - const: tx
+      - const: rx
+
+  interrupts:
+    maxItems: 1
+
+  "#mbox-cells":
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - reg-names
+  - interrupts
+  - "#mbox-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+
+    mailbox@12c1c200 {
+        compatible = "aspeed,ast2700-mailbox";
+        reg = <0x12c1c200 0x100>, <0x12c1c300 0x100>;
+        reg-names = "tx", "rx";
+        interrupts = <GIC_SPI 103 IRQ_TYPE_LEVEL_HIGH>;
+        #mbox-cells = <1>;
+    };
-- 
2.25.1

[PATCH v6 2/2] mailbox: aspeed: add mailbox driver for AST27XX series SoC

[Jammy Huang]

Add mailbox controller driver for AST27XX SoCs, which provides
independent tx/rx mailbox between different processors. There are 4
channels for each tx/rx mailbox and each channel has an 32-byte FIFO.

Signed-off-by: Jammy Huang <jammy_huang@aspeedtech.com>
---
 drivers/mailbox/Kconfig           |   8 +
 drivers/mailbox/Makefile          |   2 +
 drivers/mailbox/ast2700-mailbox.c | 240 ++++++++++++++++++++++++++++++
 3 files changed, 250 insertions(+)
 create mode 100644 drivers/mailbox/ast2700-mailbox.c

diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index 68eeed660a4a..1c38cd570091 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -340,4 +340,12 @@ config THEAD_TH1520_MBOX
 	  kernel is running, and E902 core used for power management among other
 	  things.
 
+config AST2700_MBOX
+	tristate "ASPEED AST2700 IPC driver"
+	depends on ARCH_ASPEED || COMPILE_TEST
+	help
+	  Mailbox driver implementation for ASPEED AST27XX SoCs. This driver
+	  can be used to send message between different processors in SoC.
+	  The driver provides mailbox support for sending interrupts to the
+	  clients. Say Y here if you want to build this driver.
 endif
diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
index 13a3448b3271..9a9add9a7548 100644
--- a/drivers/mailbox/Makefile
+++ b/drivers/mailbox/Makefile
@@ -72,3 +72,5 @@ obj-$(CONFIG_QCOM_CPUCP_MBOX)	+= qcom-cpucp-mbox.o
 obj-$(CONFIG_QCOM_IPCC)		+= qcom-ipcc.o
 
 obj-$(CONFIG_THEAD_TH1520_MBOX)	+= mailbox-th1520.o
+
+obj-$(CONFIG_AST2700_MBOX)	+= ast2700-mailbox.o
diff --git a/drivers/mailbox/ast2700-mailbox.c b/drivers/mailbox/ast2700-mailbox.c
new file mode 100644
index 000000000000..6d9269e89979
--- /dev/null
+++ b/drivers/mailbox/ast2700-mailbox.c
@@ -0,0 +1,240 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright Aspeed Technology Inc. (C) 2025. All rights reserved
+ */
+
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/kernel.h>
+#include <linux/mailbox_controller.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+/* Each bit in the register represents an IPC ID */
+#define IPCR_TX_TRIG		0x00
+#define IPCR_ENABLE		0x04
+#define IPCR_STATUS		0x08
+#define  RX_IRQ(n)		BIT(n)
+#define  RX_IRQ_MASK		0xf
+#define IPCR_DATA		0x10
+
+struct ast2700_mbox_data {
+	u8 num_chans;
+	u8 msg_size;
+};
+
+struct ast2700_mbox {
+	struct mbox_controller mbox;
+	u8 msg_size;
+	void __iomem *tx_regs;
+	void __iomem *rx_regs;
+	spinlock_t lock;
+};
+
+static inline int ch_num(struct mbox_chan *chan)
+{
+	return chan - chan->mbox->chans;
+}
+
+static inline bool ast2700_mbox_tx_done(struct ast2700_mbox *mb, int idx)
+{
+	return !(readl(mb->tx_regs + IPCR_STATUS) & BIT(idx));
+}
+
+static irqreturn_t ast2700_mbox_irq(int irq, void *p)
+{
+	struct ast2700_mbox *mb = p;
+	void __iomem *data_reg;
+	int num_words;
+	u32 *word_data;
+	u32 status;
+	int n;
+
+	/* Only examine channels that are currently enabled. */
+	status = readl(mb->rx_regs + IPCR_ENABLE) &
+		 readl(mb->rx_regs + IPCR_STATUS);
+
+	if (!(status & RX_IRQ_MASK))
+		return IRQ_NONE;
+
+	for (n = 0; n < mb->mbox.num_chans; ++n) {
+		struct mbox_chan *chan = &mb->mbox.chans[n];
+
+		if (!(status & RX_IRQ(n)))
+			continue;
+
+		/* Read the message data */
+		for (data_reg = mb->rx_regs + IPCR_DATA + mb->msg_size * n,
+		     word_data = chan->con_priv,
+		     num_words = (mb->msg_size / sizeof(u32));
+		     num_words;
+		     num_words--, data_reg += sizeof(u32), word_data++)
+			*word_data = readl(data_reg);
+
+		mbox_chan_received_data(chan, chan->con_priv);
+
+		/* The IRQ can be cleared only once the FIFO is empty. */
+		writel(RX_IRQ(n), mb->rx_regs + IPCR_STATUS);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int ast2700_mbox_send_data(struct mbox_chan *chan, void *data)
+{
+	struct ast2700_mbox *mb = dev_get_drvdata(chan->mbox->dev);
+	void __iomem *data_reg;
+	u32 *word_data;
+	int num_words;
+	int idx = ch_num(chan);
+
+	if (!(readl(mb->tx_regs + IPCR_ENABLE) & BIT(idx))) {
+		dev_warn(mb->mbox.dev, "%s: Ch-%d not enabled yet\n", __func__, idx);
+		return -ENODEV;
+	}
+
+	if (!(ast2700_mbox_tx_done(mb, idx))) {
+		dev_warn(mb->mbox.dev, "%s: Ch-%d last data has not finished\n", __func__, idx);
+		return -EBUSY;
+	}
+
+	/* Write the message data */
+	for (data_reg = mb->tx_regs + IPCR_DATA + mb->msg_size * idx,
+	     word_data = (u32 *)data,
+	     num_words = (mb->msg_size / sizeof(u32));
+	     num_words;
+	     num_words--, data_reg += sizeof(u32), word_data++)
+		writel(*word_data, data_reg);
+
+	writel(BIT(idx), mb->tx_regs + IPCR_TX_TRIG);
+	dev_dbg(mb->mbox.dev, "%s: Ch-%d sent\n", __func__, idx);
+
+	return 0;
+}
+
+static int ast2700_mbox_startup(struct mbox_chan *chan)
+{
+	struct ast2700_mbox *mb = dev_get_drvdata(chan->mbox->dev);
+	int idx = ch_num(chan);
+	void __iomem *reg = mb->rx_regs + IPCR_ENABLE;
+	unsigned long flags;
+
+	spin_lock_irqsave(&mb->lock, flags);
+	writel(readl(reg) | BIT(idx), reg);
+	spin_unlock_irqrestore(&mb->lock, flags);
+
+	return 0;
+}
+
+static void ast2700_mbox_shutdown(struct mbox_chan *chan)
+{
+	struct ast2700_mbox *mb = dev_get_drvdata(chan->mbox->dev);
+	int idx = ch_num(chan);
+	void __iomem *reg = mb->rx_regs + IPCR_ENABLE;
+	unsigned long flags;
+
+	spin_lock_irqsave(&mb->lock, flags);
+	writel(readl(reg) & ~BIT(idx), reg);
+	spin_unlock_irqrestore(&mb->lock, flags);
+}
+
+static bool ast2700_mbox_last_tx_done(struct mbox_chan *chan)
+{
+	struct ast2700_mbox *mb = dev_get_drvdata(chan->mbox->dev);
+	int idx = ch_num(chan);
+
+	return ast2700_mbox_tx_done(mb, idx);
+}
+
+static const struct mbox_chan_ops ast2700_mbox_chan_ops = {
+	.send_data	= ast2700_mbox_send_data,
+	.startup	= ast2700_mbox_startup,
+	.shutdown	= ast2700_mbox_shutdown,
+	.last_tx_done	= ast2700_mbox_last_tx_done,
+};
+
+static int ast2700_mbox_probe(struct platform_device *pdev)
+{
+	struct ast2700_mbox *mb;
+	const struct ast2700_mbox_data *dev_data;
+	struct device *dev = &pdev->dev;
+	int irq, ret;
+
+	if (!pdev->dev.of_node)
+		return -ENODEV;
+
+	dev_data = device_get_match_data(&pdev->dev);
+
+	mb = devm_kzalloc(dev, sizeof(*mb), GFP_KERNEL);
+	if (!mb)
+		return -ENOMEM;
+
+	mb->mbox.chans = devm_kcalloc(&pdev->dev, dev_data->num_chans,
+				      sizeof(*mb->mbox.chans), GFP_KERNEL);
+	if (!mb->mbox.chans)
+		return -ENOMEM;
+
+	/* con_priv of each channel is used to store the message received */
+	for (int i = 0; i < dev_data->num_chans; i++) {
+		mb->mbox.chans[i].con_priv = devm_kcalloc(dev, dev_data->msg_size,
+							  sizeof(u8), GFP_KERNEL);
+		if (!mb->mbox.chans[i].con_priv)
+			return -ENOMEM;
+	}
+
+	platform_set_drvdata(pdev, mb);
+
+	mb->tx_regs = devm_platform_ioremap_resource_byname(pdev, "tx");
+	if (IS_ERR(mb->tx_regs))
+		return PTR_ERR(mb->tx_regs);
+
+	mb->rx_regs = devm_platform_ioremap_resource_byname(pdev, "rx");
+	if (IS_ERR(mb->rx_regs))
+		return PTR_ERR(mb->rx_regs);
+
+	mb->msg_size = dev_data->msg_size;
+	mb->mbox.dev = dev;
+	mb->mbox.num_chans = dev_data->num_chans;
+	mb->mbox.ops = &ast2700_mbox_chan_ops;
+	mb->mbox.txdone_irq = false;
+	mb->mbox.txdone_poll = true;
+	mb->mbox.txpoll_period = 5;
+	spin_lock_init(&mb->lock);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	ret = devm_request_irq(dev, irq, ast2700_mbox_irq, 0, dev_name(dev), mb);
+	if (ret)
+		return ret;
+
+	return devm_mbox_controller_register(dev, &mb->mbox);
+}
+
+static const struct ast2700_mbox_data ast2700_dev_data = {
+	.num_chans = 4,
+	.msg_size = 0x20,
+};
+
+static const struct of_device_id ast2700_mbox_of_match[] = {
+	{ .compatible = "aspeed,ast2700-mailbox", .data = &ast2700_dev_data },
+	{}
+};
+MODULE_DEVICE_TABLE(of, ast2700_mbox_of_match);
+
+static struct platform_driver ast2700_mbox_driver = {
+	.driver = {
+		.name = "ast2700-mailbox",
+		.of_match_table = ast2700_mbox_of_match,
+	},
+	.probe = ast2700_mbox_probe,
+};
+module_platform_driver(ast2700_mbox_driver);
+
+MODULE_AUTHOR("Jammy Huang <jammy_huang@aspeedtech.com>");
+MODULE_DESCRIPTION("ASPEED AST2700 IPC driver");
+MODULE_LICENSE("GPL");
-- 
2.25.1

Re: [PATCH v6 1/2] dt-bindings: mailbox: Add ASPEED AST2700 series SoC

[Andrew Jeffery]

On Wed, 2025-07-02 at 09:19 +0800, Jammy Huang wrote:
> Introduce the mailbox module for AST27XX series SoC, which is responsible
> for interchanging messages between asymmetric processors.
> 
> Signed-off-by: Jammy Huang <jammy_huang@aspeedtech.com>
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Reviewed-by: Andrew Jeffery <andrew@codeconstruct.com.au>

Re: [PATCH v6 2/2] mailbox: aspeed: add mailbox driver for AST27XX series SoC

[Andrew Jeffery]

On Wed, 2025-07-02 at 09:19 +0800, Jammy Huang wrote:
> Add mailbox controller driver for AST27XX SoCs, which provides
> independent tx/rx mailbox between different processors. There are 4
> channels for each tx/rx mailbox and each channel has an 32-byte FIFO.
> 
> Signed-off-by: Jammy Huang <jammy_huang@aspeedtech.com>

Reviewed-by: Andrew Jeffery <andrew@codeconstruct.com.au>

Re: [PATCH v6 2/2] mailbox: aspeed: add mailbox driver for AST27XX series SoC

[Jassi Brar]

On Tue, Jul 1, 2025 at 8:19 PM Jammy Huang <jammy_huang@aspeedtech.com> wrote:

.....
> +               /* Read the message data */
> +               for (data_reg = mb->rx_regs + IPCR_DATA + mb->msg_size * n,
> +                    word_data = chan->con_priv,
> +                    num_words = (mb->msg_size / sizeof(u32));
> +                    num_words;
> +                    num_words--, data_reg += sizeof(u32), word_data++)
> +                       *word_data = readl(data_reg);
> +
Please clean this for loop.

Thanks
-Jassi

RE: [PATCH v6 2/2] mailbox: aspeed: add mailbox driver for AST27XX series SoC

[Jammy Huang]

> On Tue, Jul 1, 2025 at 8:19 PM Jammy Huang
> <jammy_huang@aspeedtech.com> wrote:
> 
> .....
> > +               /* Read the message data */
> > +               for (data_reg = mb->rx_regs + IPCR_DATA +
> mb->msg_size * n,
> > +                    word_data = chan->con_priv,
> > +                    num_words = (mb->msg_size / sizeof(u32));
> > +                    num_words;
> > +                    num_words--, data_reg += sizeof(u32),
> word_data++)
> > +                       *word_data = readl(data_reg);
> > +
> Please clean this for loop.
OK, will be updated in later patch.
Thanks for help.

> 
> Thanks
> -Jassi

Regards.