mailbox driver support for Phytium desktop and embedded CPUs

Mailbox driver function patch. Support Phytium desktop and embedded processors, such as D2000 and E2000.

Reviewed-by: Hongbo Mao <maohongbo@phytium.com.cn>
(cherry picked from commit f6e90a3999)
Signed-off-by: Alex Shi <alexsshi@tencent.com>

Documentation/devicetree/bindings/mailbox/phytium-mailbox.txt

@@ -0,0 +1,32 @@
+Phytium Mailbox Driver
+======================
+
+The Phytium mailbox controller that has a channel/link to communicate
+with the remote end. A link raises interrupt for any received data. However,
+there is no specified way of knowing if the sent data has been read by the
+remote. This driver assumes the sender polls STAT register and the remote
+clears it after having read the data.
+
+Mailbox Device Node:
+====================
+
+Required properties:
+--------------------
+- compatible:          Shall be "phytium,mbox"
+- reg:                 Contains the mailbox register address range (base
+                       address and length)
+- #mbox-cells          Shall be 1 - the index of the channel needed.
+- interrupts:          Contains the interrupt information corresponding to
+                       the link.
+
+Example:
+--------
+
+mbox: mailbox@2a000000 {
+       compatible = "phytium,mbox";
+       reg = <0x0 0x2a000000 0x0 0x1000>;
+       #mbox-cells = <1>;
+       interrupts = <0 48 4>;
+       clocks = <&sycclk>;
+       clock-names = "apb_pclk";
+};

drivers/mailbox/Kconfig

@@ -22,6 +22,12 @@ config IMX_MBOX
 	help
 	  Mailbox implementation for i.MX Messaging Unit (MU).
 
+config PHYTIUM_MBOX
+       tristate "Phytium SoC Mailbox Support"
+       depends on ARCH_PHYTIUM || COMPILE_TEST
+       help
+         This driver provides the support for the Phytium mailbox controller.
+
 config PLATFORM_MHU
 	tristate "Platform MHU Mailbox"
 	depends on OF

drivers/mailbox/Makefile

@@ -11,6 +11,8 @@ obj-$(CONFIG_IMX_MBOX)	+= imx-mailbox.o
 
 obj-$(CONFIG_ARMADA_37XX_RWTM_MBOX)	+= armada-37xx-rwtm-mailbox.o
 
+obj-$(CONFIG_PHYTIUM_MBOX)	+= phytium_mailbox.o
+
 obj-$(CONFIG_PLATFORM_MHU)	+= platform_mhu.o
 
 obj-$(CONFIG_PL320_MBOX)	+= pl320-ipc.o

drivers/mailbox/phytium_mailbox.c

@@ -0,0 +1,201 @@
+/*
+ * Phytium SoC mailbox driver
+ *
+ * Copyright (c) 2020 Phytium Corporation.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/acpi.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/mailbox_controller.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+
+#define INTR_STAT      0x0
+#define INTR_SET       0x8
+#define INTR_CLR       0x10
+
+#define TX_REG         0x100
+
+#define NR_CHANS       1
+
+struct phytium_mbox_link {
+       unsigned irq;
+       void __iomem *tx_reg;
+       void __iomem *rx_reg;
+};
+
+struct phytium_mbox {
+       void __iomem *base;
+       struct phytium_mbox_link mlink;
+       struct mbox_chan chan;
+       struct mbox_controller mbox;
+};
+
+static irqreturn_t phytium_mbox_rx_irq(int irq, void *ch)
+{
+       struct mbox_chan *chan = ch;
+       struct phytium_mbox_link *mlink = chan->con_priv;
+       u32 val;
+
+       val = readl_relaxed(mlink->rx_reg + INTR_STAT);
+       if (!val)
+               return IRQ_NONE;
+
+       mbox_chan_received_data(chan, (void *)&val);
+
+       writel_relaxed(val, mlink->rx_reg + INTR_CLR);
+
+       return IRQ_HANDLED;
+}
+
+static int phytium_mbox_send_data(struct mbox_chan *chan, void *data)
+{
+       struct phytium_mbox_link *mlink = chan->con_priv;
+       u32 *arg = data;
+
+       writel_relaxed(*arg, mlink->tx_reg + INTR_SET);
+
+       return 0;
+}
+
+static int phytium_mbox_startup(struct mbox_chan *chan)
+{
+       struct phytium_mbox_link *mlink = chan->con_priv;
+       u32 val;
+       int ret;
+
+       val = readl_relaxed(mlink->tx_reg + INTR_STAT);
+       writel_relaxed(val, mlink->tx_reg + INTR_CLR);
+
+       ret = request_irq(mlink->irq, phytium_mbox_rx_irq,
+                         IRQF_SHARED, "phytium_mbox_link", chan);
+       if (ret) {
+               dev_err(chan->mbox->dev,
+                       "Unable to acquire IRQ %d\n", mlink->irq);
+       }
+
+       return ret;
+}
+
+static void phytium_mbox_shutdown(struct mbox_chan *chan)
+{
+       struct phytium_mbox_link *mlink = chan->con_priv;
+
+       free_irq(mlink->irq, chan);
+}
+
+static bool phytium_mbox_last_tx_done(struct mbox_chan *chan)
+{
+       struct phytium_mbox_link *mlink = chan->con_priv;
+       u32 val = readl_relaxed(mlink->tx_reg + INTR_STAT);
+
+       return (val == (u32)(1U << 31));
+}
+
+static const struct mbox_chan_ops phytium_mbox_ops = {
+       .send_data = phytium_mbox_send_data,
+       .startup = phytium_mbox_startup,
+       .shutdown = phytium_mbox_shutdown,
+       .last_tx_done = phytium_mbox_last_tx_done,
+};
+
+static const struct acpi_device_id phytium_mbox_acpi_match[] = {
+       { "PHYT0009", 0 },
+       { },
+};
+MODULE_DEVICE_TABLE(acpi, phytium_mbox_acpi_match);
+
+static const struct of_device_id phytium_mbox_of_match[] = {
+       { .compatible = "phytium,mbox", },
+       { },
+};
+MODULE_DEVICE_TABLE(of, phytium_mbox_of_match);
+
+static int phytium_mbox_probe(struct platform_device *pdev)
+{
+       struct phytium_mbox *mbox;
+       struct resource *res;
+       int err, irq;
+
+       /* Allocate memory for device */
+       mbox = devm_kzalloc(&pdev->dev, sizeof(*mbox), GFP_KERNEL);
+       if (!mbox)
+               return -ENOMEM;
+
+       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+       mbox->base = devm_ioremap_resource(&pdev->dev, res);
+       if (IS_ERR(mbox->base)) {
+               dev_err(&pdev->dev, "ioremap base failed\n");
+               return PTR_ERR(mbox->base);
+       }
+
+       irq = platform_get_irq(pdev, 0);
+       if (irq < 0) {
+               dev_err(&pdev->dev, "cannot obtain irq\n");
+               return irq;
+       }
+
+       mbox->chan.con_priv = &mbox->mlink;
+       mbox->mlink.irq = irq;
+       mbox->mlink.rx_reg = mbox->base;
+       mbox->mlink.tx_reg = mbox->mlink.rx_reg + TX_REG;
+
+       mbox->mbox.dev = &pdev->dev;
+       mbox->mbox.chans = &mbox->chan;
+       mbox->mbox.num_chans = NR_CHANS;
+       mbox->mbox.ops = &phytium_mbox_ops;
+       mbox->mbox.txdone_irq = false;
+       mbox->mbox.txdone_poll = true;
+       mbox->mbox.txpoll_period = 1;
+
+       platform_set_drvdata(pdev, mbox);
+
+       err = mbox_controller_register(&mbox->mbox);
+       if (err) {
+               dev_err(&pdev->dev, "Failed to register mailboxes %d\n", err);
+               goto fail;
+       }
+
+       dev_info(&pdev->dev, "Phytium SoC Mailbox registered\n");
+fail:
+       return err;
+}
+
+static int phytium_mbox_remove(struct platform_device *pdev)
+{
+       struct phytium_mbox *mbox = platform_get_drvdata(pdev);
+
+       mbox_controller_unregister(&mbox->mbox);
+
+       return 0;
+}
+
+static struct platform_driver phytium_mbox_driver = {
+       .probe = phytium_mbox_probe,
+       .remove = phytium_mbox_remove,
+       .driver = {
+               .name = "phytium-mbox",
+               .of_match_table = of_match_ptr(phytium_mbox_of_match),
+               .acpi_match_table = ACPI_PTR(phytium_mbox_acpi_match),
+       },
+};
+
+module_platform_driver(phytium_mbox_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Phytium SoC Mailbox Driver");
+MODULE_AUTHOR("Chen Baozi <chenbaozi@phytium.com.cn>");
+MODULE_AUTHOR("Chen Ziqiang <chenziqiang1686@phytium.com.cn>");