[PATCH V4 2/5] 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.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
Signed-off-by: Sibi Sankar <quic_sibis@xxxxxxxxxxx>
---

V3:
* Fix copyright info in cpucp driver. [Bjorn]
* Drop unused APSS_CPUCP_TX_MBOX_IDR, value init and drv_data. [Bjorn/Dmitry]
* Convert to lower case hex. [Bjorn]
* Convert irq and dev to local variables. [Bjorn]
* Replace for and if with for_each_set_bit. [Bjorn]
* Document the need for spinlock. [Bjorn]
* Add space after " for aesthetics. [Bjorn]
* Include io.h and re-order platform_device.h
* Use GENMASK_ULL to generate APSS_CPUCP_RX_MBOX_CMD_MASK.
* Pick Rb.

 drivers/mailbox/Kconfig           |   8 ++
 drivers/mailbox/Makefile          |   2 +
 drivers/mailbox/qcom-cpucp-mbox.c | 179 ++++++++++++++++++++++++++++++
 3 files changed, 189 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..78d0872a0e33
--- /dev/null
+++ b/drivers/mailbox/qcom-cpucp-mbox.c
@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2024, Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#include <linux/bitops.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+#include <linux/mailbox_controller.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#define APSS_CPUCP_IPC_CHAN_SUPPORTED		3
+#define APSS_CPUCP_MBOX_CMD_OFF			0x4
+
+/* Tx Registers */
+#define APSS_CPUCP_TX_MBOX_CMD(i)		(0x100 + ((i) * 8))
+
+/* Rx Registers */
+#define APSS_CPUCP_RX_MBOX_CMD(i)		(0x100 + ((i) * 8))
+#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		GENMASK_ULL(63, 0)
+
+/**
+ * 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
+ */
+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;
+};
+
+static inline int channel_number(struct mbox_chan *chan)
+{
+	return chan - chan->mbox->chans;
+}
+
+static irqreturn_t qcom_cpucp_mbox_irq_fn(int irq, void *data)
+{
+	struct qcom_cpucp_mbox *cpucp = data;
+	struct mbox_chan *chan;
+	unsigned long flags;
+	u64 status;
+	u32 val;
+	int i;
+
+	status = readq(cpucp->rx_base + APSS_CPUCP_RX_MBOX_STAT);
+
+	for_each_set_bit(i, (unsigned long *)&status, APSS_CPUCP_IPC_CHAN_SUPPORTED) {
+		val = readl(cpucp->rx_base + APSS_CPUCP_RX_MBOX_CMD(i) + APSS_CPUCP_MBOX_CMD_OFF);
+		chan = &cpucp->chans[i];
+		/* Provide mutual exclusion with changes to chan->cl */
+		spin_lock_irqsave(&chan->lock, flags);
+		if (chan->cl)
+			mbox_chan_received_data(chan, &val);
+		writeq(BIT(i), cpucp->rx_base + APSS_CPUCP_RX_MBOX_CLEAR);
+		spin_unlock_irqrestore(&chan->lock, flags);
+	}
+
+	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 = channel_number(chan);
+	u64 val;
+
+	val = readq(cpucp->rx_base + APSS_CPUCP_RX_MBOX_EN);
+	val |= BIT(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 = channel_number(chan);
+	u64 val;
+
+	val = readq(cpucp->rx_base + APSS_CPUCP_RX_MBOX_EN);
+	val &= ~BIT(chan_id);
+	writeq(val, cpucp->rx_base + APSS_CPUCP_RX_MBOX_EN);
+}
+
+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 = channel_number(chan);
+	u32 *val = data;
+
+	writel(*val, cpucp->tx_base + APSS_CPUCP_TX_MBOX_CMD(chan_id) + APSS_CPUCP_MBOX_CMD_OFF);
+
+	return 0;
+}
+
+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_mbox_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct qcom_cpucp_mbox *cpucp;
+	struct mbox_controller *mbox;
+	int irq, ret;
+
+	cpucp = devm_kzalloc(dev, sizeof(*cpucp), GFP_KERNEL);
+	if (!cpucp)
+		return -ENOMEM;
+
+	cpucp->rx_base = devm_of_iomap(dev, dev->of_node, 0, NULL);
+	if (IS_ERR(cpucp->rx_base))
+		return PTR_ERR(cpucp->rx_base);
+
+	cpucp->tx_base = devm_of_iomap(dev, dev->of_node, 1, NULL);
+	if (IS_ERR(cpucp->tx_base))
+		return PTR_ERR(cpucp->tx_base);
+
+	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);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	ret = devm_request_irq(dev, irq, qcom_cpucp_mbox_irq_fn,
+			       IRQF_TRIGGER_HIGH, "apss_cpucp_mbox", cpucp);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Failed to register irq: %d\n", irq);
+
+	writeq(APSS_CPUCP_RX_MBOX_CMD_MASK, cpucp->rx_base + APSS_CPUCP_RX_MBOX_MAP);
+
+	mbox = &cpucp->mbox;
+	mbox->dev = dev;
+	mbox->num_chans = APSS_CPUCP_IPC_CHAN_SUPPORTED;
+	mbox->chans = cpucp->chans;
+	mbox->ops = &qcom_cpucp_mbox_chan_ops;
+	mbox->txdone_irq = false;
+	mbox->txdone_poll = false;
+
+	ret = devm_mbox_controller_register(dev, mbox);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to create mailbox\n");
+
+	return 0;
+}
+
+static const struct of_device_id qcom_cpucp_mbox_of_match[] = {
+	{ .compatible = "qcom,x1e80100-cpucp-mbox" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, qcom_cpucp_mbox_of_match);
+
+static struct platform_driver qcom_cpucp_mbox_driver = {
+	.probe = qcom_cpucp_mbox_probe,
+	.driver = {
+		.name = "qcom_cpucp_mbox",
+		.of_match_table = qcom_cpucp_mbox_of_match,
+	},
+};
+module_platform_driver(qcom_cpucp_mbox_driver);
+
+MODULE_DESCRIPTION("QTI CPUCP MBOX Driver");
+MODULE_LICENSE("GPL");
-- 
2.34.1