[RFC 2/7] mailbox: Add support for QTI CPUCP mailbox controller

[Sibi Sankar]

Add support for CPUSS Control Processor (CPUCP) mailbox controller,
this driver enables communication between AP and CPUCP by acting as
a doorbell between them.

Signed-off-by: Sibi Sankar <quic_sibis@xxxxxxxxxxx>
---
 drivers/mailbox/Kconfig           |   8 +
 drivers/mailbox/Makefile          |   2 +
 drivers/mailbox/qcom-cpucp-mbox.c | 265 ++++++++++++++++++++++++++++++
 3 files changed, 275 insertions(+)
 create mode 100644 drivers/mailbox/qcom-cpucp-mbox.c

diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index 42940108a187..23741a6f054e 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -273,6 +273,14 @@ config SPRD_MBOX
 	  to send message between application processors and MCU. Say Y here if
 	  you want to build the Spreatrum mailbox controller driver.
 
+config QCOM_CPUCP_MBOX
+	tristate "Qualcomm Technologies, Inc. CPUCP mailbox driver"
+	depends on ARCH_QCOM || COMPILE_TEST
+	help
+	  Qualcomm Technologies, Inc. CPUSS Control Processor (CPUCP) mailbox
+	  controller driver enables communication between AP and CPUCP. Say
+	  Y here if you want to build this driver.
+
 config QCOM_IPCC
 	tristate "Qualcomm Technologies, Inc. IPCC driver"
 	depends on ARCH_QCOM || COMPILE_TEST
diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
index 18793e6caa2f..53b512800bde 100644
--- a/drivers/mailbox/Makefile
+++ b/drivers/mailbox/Makefile
@@ -59,4 +59,6 @@ obj-$(CONFIG_SUN6I_MSGBOX)	+= sun6i-msgbox.o
 
 obj-$(CONFIG_SPRD_MBOX)		+= sprd-mailbox.o
 
+obj-$(CONFIG_QCOM_CPUCP_MBOX)	+= qcom-cpucp-mbox.o
+
 obj-$(CONFIG_QCOM_IPCC)		+= qcom-ipcc.o
diff --git a/drivers/mailbox/qcom-cpucp-mbox.c b/drivers/mailbox/qcom-cpucp-mbox.c
new file mode 100644
index 000000000000..22ea6c802286
--- /dev/null
+++ b/drivers/mailbox/qcom-cpucp-mbox.c
@@ -0,0 +1,265 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2024, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+#include <linux/platform_device.h>
+#include <linux/mailbox_controller.h>
+#include <linux/module.h>
+
+#define APSS_CPUCP_IPC_CHAN_SUPPORTED		3
+#define APSS_CPUCP_MBOX_CMD_OFF			0x4
+
+/* Tx Registers */
+#define APSS_CPUCP_TX_MBOX_IDR			0
+#define APSS_CPUCP_TX_MBOX_CMD			0x100
+
+/* Rx Registers */
+#define APSS_CPUCP_RX_MBOX_IDR			0
+#define APSS_CPUCP_RX_MBOX_CMD			0x100
+#define APSS_CPUCP_RX_MBOX_MAP			0x4000
+#define APSS_CPUCP_RX_MBOX_STAT			0x4400
+#define APSS_CPUCP_RX_MBOX_CLEAR		0x4800
+#define APSS_CPUCP_RX_MBOX_EN			0x4C00
+#define APSS_CPUCP_RX_MBOX_CMD_MASK		0xFFFFFFFFFFFFFFFF
+
+/**
+ * struct qcom_cpucp_mbox - Holder for the mailbox driver
+ * @chans:			The mailbox channel
+ * @mbox:			The mailbox controller
+ * @tx_base:			Base address of the CPUCP tx registers
+ * @rx_base:			Base address of the CPUCP rx registers
+ * @dev:			Device associated with this instance
+ * @irq:			CPUCP to AP irq
+ */
+struct qcom_cpucp_mbox {
+	struct mbox_chan chans[APSS_CPUCP_IPC_CHAN_SUPPORTED];
+	struct mbox_controller mbox;
+	void __iomem *tx_base;
+	void __iomem *rx_base;
+	struct device *dev;
+	int irq;
+	int num_chan;
+};
+
+static irqreturn_t qcom_cpucp_mbox_irq_fn(int irq, void *data)
+{
+	struct qcom_cpucp_mbox *cpucp = data;
+	u64 status;
+	u32 val;
+	int i;
+
+	status = readq(cpucp->rx_base + APSS_CPUCP_RX_MBOX_STAT);
+
+	for (i = 0; i < cpucp->num_chan; i++) {
+		val = 0;
+		if (status & ((u64)1 << i)) {
+			val = readl(cpucp->rx_base + APSS_CPUCP_RX_MBOX_CMD + (i * 8) + APSS_CPUCP_MBOX_CMD_OFF);
+			if (!IS_ERR(cpucp->chans[i].con_priv))
+				mbox_chan_received_data(&cpucp->chans[i], &val);
+			writeq(status, cpucp->rx_base + APSS_CPUCP_RX_MBOX_CLEAR);
+		}
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int qcom_cpucp_mbox_startup(struct mbox_chan *chan)
+{
+	struct qcom_cpucp_mbox *cpucp = container_of(chan->mbox, struct qcom_cpucp_mbox, mbox);
+	unsigned long chan_id = (unsigned long)chan->con_priv;
+	u64 val;
+
+	val = readq(cpucp->rx_base + APSS_CPUCP_RX_MBOX_EN);
+	val |= ((u64)1 << chan_id);
+	writeq(val, cpucp->rx_base + APSS_CPUCP_RX_MBOX_EN);
+
+	return 0;
+}
+
+static void qcom_cpucp_mbox_shutdown(struct mbox_chan *chan)
+{
+	struct qcom_cpucp_mbox *cpucp = container_of(chan->mbox, struct qcom_cpucp_mbox, mbox);
+	unsigned long chan_id = (unsigned long)chan->con_priv;
+	u64 val;
+
+	val = readq(cpucp->rx_base + APSS_CPUCP_RX_MBOX_EN);
+	val &= ~((u64)1 << chan_id);
+	writeq(val, cpucp->rx_base + APSS_CPUCP_RX_MBOX_EN);
+
+	chan->con_priv = ERR_PTR(-EINVAL);
+}
+
+static int qcom_cpucp_mbox_send_data(struct mbox_chan *chan, void *data)
+{
+	struct qcom_cpucp_mbox *cpucp = container_of(chan->mbox, struct qcom_cpucp_mbox, mbox);
+	unsigned long chan_id = (unsigned long)chan->con_priv;
+	u32 val = (unsigned long)data;
+
+	writel(val, cpucp->tx_base + APSS_CPUCP_TX_MBOX_CMD + (chan_id * 8) + APSS_CPUCP_MBOX_CMD_OFF);
+
+	return 0;
+}
+
+static struct mbox_chan *qcom_cpucp_mbox_xlate(struct mbox_controller *mbox,
+					       const struct of_phandle_args *sp)
+{
+	unsigned long ind = sp->args[0];
+
+	if (sp->args_count != 1)
+		return ERR_PTR(-EINVAL);
+
+	if (ind >= mbox->num_chans)
+		return ERR_PTR(-EINVAL);
+
+	if (!IS_ERR(mbox->chans[ind].con_priv))
+		return ERR_PTR(-EBUSY);
+
+	mbox->chans[ind].con_priv = (void *)ind;
+
+	return &mbox->chans[ind];
+}
+
+static const struct mbox_chan_ops qcom_cpucp_mbox_chan_ops = {
+	.startup = qcom_cpucp_mbox_startup,
+	.send_data = qcom_cpucp_mbox_send_data,
+	.shutdown = qcom_cpucp_mbox_shutdown
+};
+
+static int qcom_cpucp_setup_mbox(struct qcom_cpucp_mbox *cpucp)
+{
+	struct device *dev = cpucp->dev;
+	struct mbox_controller *mbox;
+	unsigned long i;
+
+	/* Initialize channel identifiers */
+	for (i = 0; i < ARRAY_SIZE(cpucp->chans); i++)
+		cpucp->chans[i].con_priv = ERR_PTR(-EINVAL);
+
+	mbox = &cpucp->mbox;
+	mbox->dev = dev;
+	mbox->num_chans = cpucp->num_chan;
+	mbox->chans = cpucp->chans;
+	mbox->ops = &qcom_cpucp_mbox_chan_ops;
+	mbox->of_xlate = qcom_cpucp_mbox_xlate;
+	mbox->txdone_irq = false;
+	mbox->txdone_poll = false;
+
+	return mbox_controller_register(mbox);
+}
+
+static int qcom_cpucp_mbox_probe(struct platform_device *pdev)
+{
+	struct qcom_cpucp_mbox *cpucp;
+	struct resource *res;
+	int ret;
+
+	cpucp = devm_kzalloc(&pdev->dev, sizeof(*cpucp), GFP_KERNEL);
+	if (!cpucp)
+		return -ENOMEM;
+
+	cpucp->dev = &pdev->dev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "Failed to get the cpucp rx base address\n");
+		return -ENODEV;
+	}
+
+	cpucp->rx_base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
+	if (!cpucp->rx_base) {
+		dev_err(&pdev->dev, "Failed to ioremap cpucp tx base\n");
+		return -ENOMEM;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	if (!res) {
+		dev_err(&pdev->dev, "Failed to get the cpucp tx base address\n");
+		return -ENODEV;
+	}
+
+	cpucp->tx_base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
+	if (!cpucp->tx_base) {
+		dev_err(&pdev->dev, "Failed to ioremap cpucp tx base\n");
+		return -ENOMEM;
+	}
+
+	writeq(0, cpucp->rx_base + APSS_CPUCP_RX_MBOX_EN);
+	writeq(0, cpucp->rx_base + APSS_CPUCP_RX_MBOX_CLEAR);
+	writeq(0, cpucp->rx_base + APSS_CPUCP_RX_MBOX_MAP);
+
+	cpucp->irq = platform_get_irq(pdev, 0);
+	if (cpucp->irq < 0) {
+		dev_err(&pdev->dev, "Failed to get the IRQ\n");
+		return cpucp->irq;
+	}
+
+	ret = devm_request_irq(&pdev->dev, cpucp->irq, qcom_cpucp_mbox_irq_fn,
+			       IRQF_TRIGGER_HIGH, "apss_cpucp_mbox", cpucp);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to register the irq: %d\n", ret);
+		return ret;
+	}
+
+	writeq(APSS_CPUCP_RX_MBOX_CMD_MASK, cpucp->rx_base + APSS_CPUCP_RX_MBOX_MAP);
+
+	cpucp->num_chan = APSS_CPUCP_IPC_CHAN_SUPPORTED;
+	ret = qcom_cpucp_setup_mbox(cpucp);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to create mailbox\n");
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, cpucp);
+
+	return 0;
+}
+
+static int qcom_cpucp_mbox_remove(struct platform_device *pdev)
+{
+	struct qcom_cpucp_mbox *cpucp = platform_get_drvdata(pdev);
+
+	mbox_controller_unregister(&cpucp->mbox);
+
+	return 0;
+}
+
+static const struct of_device_id qcom_cpucp_mbox_of_match[] = {
+	{ .compatible = "qcom,cpucp-mbox"},
+	{}
+};
+MODULE_DEVICE_TABLE(of, qcom_cpucp_mbox_of_match);
+
+static struct platform_driver qcom_cpucp_mbox_driver = {
+	.probe = qcom_cpucp_mbox_probe,
+	.remove = qcom_cpucp_mbox_remove,
+	.driver = {
+		.name = "qcom_cpucp_mbox",
+		.of_match_table = qcom_cpucp_mbox_of_match,
+		.suppress_bind_attrs = true,
+	},
+};
+
+static int __init qcom_cpucp_mbox_init(void)
+{
+	int ret;
+
+	ret = platform_driver_register(&qcom_cpucp_mbox_driver);
+	if (ret)
+		pr_err("%s: qcom_cpucp_mbox register failed %d\n", __func__, ret);
+
+	return ret;
+}
+module_init(qcom_cpucp_mbox_init);
+
+static __exit void qcom_cpucp_mbox_exit(void)
+{
+	platform_driver_unregister(&qcom_cpucp_mbox_driver);
+}
+module_exit(qcom_cpucp_mbox_exit);
+
+MODULE_DESCRIPTION("QTI CPUCP MBOX Driver");
+MODULE_LICENSE("GPL");
-- 
2.34.1