mailbox: Add support for i.MX messaging unit

The i.MX Messaging Unit is a two side block which allows applications
implement communication over this sides.

The MU includes the following features:
- Messaging control by interrupts or by polling
- Four general-purpose interrupt requests reflected to the other side
- Three general-purpose flags reflected to the other side
- Four receive registers with maskable interrupt
- Four transmit registers with maskable interrupt

Reviewed-by: Vladimir Zapolskiy <vz@mleia.com>
Reviewed-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

3 files changed, 366 insertions, 0 deletions

diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index 2bbabc907add..841c005d8ebb 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -15,6 +15,12 @@ config ARM_MHU
           The controller has 3 mailbox channels, the last of which can be
           used in Secure mode only.
 
+config IMX_MBOX
+        tristate "i.MX Mailbox"
+        depends on ARCH_MXC || COMPILE_TEST
+        help
+          Mailbox implementation for i.MX Messaging Unit (MU).
+
 config PLATFORM_MHU
         tristate "Platform MHU Mailbox"
         depends on OF
diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
index 4b0080480661..c818b5d011ae 100644
--- a/drivers/mailbox/Makefile
+++ b/drivers/mailbox/Makefile
@@ -7,6 +7,8 @@ obj-$(CONFIG_MAILBOX_TEST)	+= mailbox-test.o
 
 obj-$(CONFIG_ARM_MHU)   += arm_mhu.o
 
+obj-$(CONFIG_IMX_MBOX)  += imx-mailbox.o
+
 obj-$(CONFIG_PLATFORM_MHU)      += platform_mhu.o
 
 obj-$(CONFIG_PL320_MBOX)        += pl320-ipc.o
diff --git a/drivers/mailbox/imx-mailbox.c b/drivers/mailbox/imx-mailbox.c
new file mode 100644
index 000000000000..363d35d5e49d
--- /dev/null
+++ b/drivers/mailbox/imx-mailbox.c
@@ -0,0 +1,358 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018 Pengutronix, Oleksij Rempel <o.rempel@pengutronix.de>
+ */
+
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mailbox_controller.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/slab.h>
+
+/* Transmit Register */
+#define IMX_MU_xTRn(x)          (0x00 + 4 * (x))
+/* Receive Register */
+#define IMX_MU_xRRn(x)          (0x10 + 4 * (x))
+/* Status Register */
+#define IMX_MU_xSR              0x20
+#define IMX_MU_xSR_GIPn(x)      BIT(28 + (3 - (x)))
+#define IMX_MU_xSR_RFn(x)       BIT(24 + (3 - (x)))
+#define IMX_MU_xSR_TEn(x)       BIT(20 + (3 - (x)))
+#define IMX_MU_xSR_BRDIP        BIT(9)
+
+/* Control Register */
+#define IMX_MU_xCR              0x24
+/* General Purpose Interrupt Enable */
+#define IMX_MU_xCR_GIEn(x)      BIT(28 + (3 - (x)))
+/* Receive Interrupt Enable */
+#define IMX_MU_xCR_RIEn(x)      BIT(24 + (3 - (x)))
+/* Transmit Interrupt Enable */
+#define IMX_MU_xCR_TIEn(x)      BIT(20 + (3 - (x)))
+/* General Purpose Interrupt Request */
+#define IMX_MU_xCR_GIRn(x)      BIT(16 + (3 - (x)))
+
+#define IMX_MU_CHANS            16
+#define IMX_MU_CHAN_NAME_SIZE   20
+
+enum imx_mu_chan_type {
+        IMX_MU_TYPE_TX,         /* Tx */
+        IMX_MU_TYPE_RX,         /* Rx */
+        IMX_MU_TYPE_TXDB,       /* Tx doorbell */
+        IMX_MU_TYPE_RXDB,       /* Rx doorbell */
+};
+
+struct imx_mu_con_priv {
+        unsigned int            idx;
+        char                    irq_desc[IMX_MU_CHAN_NAME_SIZE];
+        enum imx_mu_chan_type   type;
+        struct mbox_chan        *chan;
+        struct tasklet_struct   txdb_tasklet;
+};
+
+struct imx_mu_priv {
+        struct device           *dev;
+        void __iomem            *base;
+        spinlock_t              xcr_lock; /* control register lock */
+
+        struct mbox_controller  mbox;
+        struct mbox_chan        mbox_chans[IMX_MU_CHANS];
+
+        struct imx_mu_con_priv  con_priv[IMX_MU_CHANS];
+        struct clk              *clk;
+        int                     irq;
+
+        bool                    side_b;
+};
+
+static struct imx_mu_priv *to_imx_mu_priv(struct mbox_controller *mbox)
+{
+        return container_of(mbox, struct imx_mu_priv, mbox);
+}
+
+static void imx_mu_write(struct imx_mu_priv *priv, u32 val, u32 offs)
+{
+        iowrite32(val, priv->base + offs);
+}
+
+static u32 imx_mu_read(struct imx_mu_priv *priv, u32 offs)
+{
+        return ioread32(priv->base + offs);
+}
+
+static u32 imx_mu_xcr_rmw(struct imx_mu_priv *priv, u32 set, u32 clr)
+{
+        unsigned long flags;
+        u32 val;
+
+        spin_lock_irqsave(&priv->xcr_lock, flags);
+        val = imx_mu_read(priv, IMX_MU_xCR);
+        val &= ~clr;
+        val |= set;
+        imx_mu_write(priv, val, IMX_MU_xCR);
+        spin_unlock_irqrestore(&priv->xcr_lock, flags);
+
+        return val;
+}
+
+static void imx_mu_txdb_tasklet(unsigned long data)
+{
+        struct imx_mu_con_priv *cp = (struct imx_mu_con_priv *)data;
+
+        mbox_chan_txdone(cp->chan, 0);
+}
+
+static irqreturn_t imx_mu_isr(int irq, void *p)
+{
+        struct mbox_chan *chan = p;
+        struct imx_mu_priv *priv = to_imx_mu_priv(chan->mbox);
+        struct imx_mu_con_priv *cp = chan->con_priv;
+        u32 val, ctrl, dat;
+
+        ctrl = imx_mu_read(priv, IMX_MU_xCR);
+        val = imx_mu_read(priv, IMX_MU_xSR);
+
+        switch (cp->type) {
+        case IMX_MU_TYPE_TX:
+                val &= IMX_MU_xSR_TEn(cp->idx) &
+                        (ctrl & IMX_MU_xCR_TIEn(cp->idx));
+                break;
+        case IMX_MU_TYPE_RX:
+                val &= IMX_MU_xSR_RFn(cp->idx) &
+                        (ctrl & IMX_MU_xCR_RIEn(cp->idx));
+                break;
+        case IMX_MU_TYPE_RXDB:
+                val &= IMX_MU_xSR_GIPn(cp->idx) &
+                        (ctrl & IMX_MU_xCR_GIEn(cp->idx));
+                break;
+        default:
+                break;
+        }
+
+        if (!val)
+                return IRQ_NONE;
+
+        if (val == IMX_MU_xSR_TEn(cp->idx)) {
+                imx_mu_xcr_rmw(priv, 0, IMX_MU_xCR_TIEn(cp->idx));
+                mbox_chan_txdone(chan, 0);
+        } else if (val == IMX_MU_xSR_RFn(cp->idx)) {
+                dat = imx_mu_read(priv, IMX_MU_xRRn(cp->idx));
+                mbox_chan_received_data(chan, (void *)&dat);
+        } else if (val == IMX_MU_xSR_GIPn(cp->idx)) {
+                imx_mu_write(priv, IMX_MU_xSR_GIPn(cp->idx), IMX_MU_xSR);
+                mbox_chan_received_data(chan, NULL);
+        } else {
+                dev_warn_ratelimited(priv->dev, "Not handled interrupt\n");
+                return IRQ_NONE;
+        }
+
+        return IRQ_HANDLED;
+}
+
+static int imx_mu_send_data(struct mbox_chan *chan, void *data)
+{
+        struct imx_mu_priv *priv = to_imx_mu_priv(chan->mbox);
+        struct imx_mu_con_priv *cp = chan->con_priv;
+        u32 *arg = data;
+
+        switch (cp->type) {
+        case IMX_MU_TYPE_TX:
+                imx_mu_write(priv, *arg, IMX_MU_xTRn(cp->idx));
+                imx_mu_xcr_rmw(priv, IMX_MU_xCR_TIEn(cp->idx), 0);
+                break;
+        case IMX_MU_TYPE_TXDB:
+                imx_mu_xcr_rmw(priv, IMX_MU_xCR_GIRn(cp->idx), 0);
+                tasklet_schedule(&cp->txdb_tasklet);
+                break;
+        default:
+                dev_warn_ratelimited(priv->dev, "Send data on wrong channel type: %d\n", cp->type);
+                return -EINVAL;
+        }
+
+        return 0;
+}
+
+static int imx_mu_startup(struct mbox_chan *chan)
+{
+        struct imx_mu_priv *priv = to_imx_mu_priv(chan->mbox);
+        struct imx_mu_con_priv *cp = chan->con_priv;
+        int ret;
+
+        if (cp->type == IMX_MU_TYPE_TXDB) {
+                /* Tx doorbell don't have ACK support */
+                tasklet_init(&cp->txdb_tasklet, imx_mu_txdb_tasklet,
+                             (unsigned long)cp);
+                return 0;
+        }
+
+        ret = request_irq(priv->irq, imx_mu_isr, IRQF_SHARED, cp->irq_desc,
+                          chan);
+        if (ret) {
+                dev_err(priv->dev,
+                        "Unable to acquire IRQ %d\n", priv->irq);
+                return ret;
+        }
+
+        switch (cp->type) {
+        case IMX_MU_TYPE_RX:
+                imx_mu_xcr_rmw(priv, IMX_MU_xCR_RIEn(cp->idx), 0);
+                break;
+        case IMX_MU_TYPE_RXDB:
+                imx_mu_xcr_rmw(priv, IMX_MU_xCR_GIEn(cp->idx), 0);
+                break;
+        default:
+                break;
+        }
+
+        return 0;
+}
+
+static void imx_mu_shutdown(struct mbox_chan *chan)
+{
+        struct imx_mu_priv *priv = to_imx_mu_priv(chan->mbox);
+        struct imx_mu_con_priv *cp = chan->con_priv;
+
+        if (cp->type == IMX_MU_TYPE_TXDB)
+                tasklet_kill(&cp->txdb_tasklet);
+
+        imx_mu_xcr_rmw(priv, 0,
+                   IMX_MU_xCR_TIEn(cp->idx) | IMX_MU_xCR_RIEn(cp->idx));
+
+        free_irq(priv->irq, chan);
+}
+
+static const struct mbox_chan_ops imx_mu_ops = {
+        .send_data = imx_mu_send_data,
+        .startup = imx_mu_startup,
+        .shutdown = imx_mu_shutdown,
+};
+
+static struct mbox_chan * imx_mu_xlate(struct mbox_controller *mbox,
+                                       const struct of_phandle_args *sp)
+{
+        u32 type, idx, chan;
+
+        if (sp->args_count != 2) {
+                dev_err(mbox->dev, "Invalid argument count %d\n", sp->args_count);
+                return ERR_PTR(-EINVAL);
+        }
+
+        type = sp->args[0]; /* channel type */
+        idx = sp->args[1]; /* index */
+        chan = type * 4 + idx;
+
+        if (chan >= mbox->num_chans) {
+                dev_err(mbox->dev, "Not supported channel number: %d. (type: %d, idx: %d)\n", chan, type, idx);
+                return ERR_PTR(-EINVAL);
+        }
+
+        return &mbox->chans[chan];
+}
+
+static void imx_mu_init_generic(struct imx_mu_priv *priv)
+{
+        if (priv->side_b)
+                return;
+
+        /* Set default MU configuration */
+        imx_mu_write(priv, 0, IMX_MU_xCR);
+}
+
+static int imx_mu_probe(struct platform_device *pdev)
+{
+        struct device *dev = &pdev->dev;
+        struct device_node *np = dev->of_node;
+        struct resource *iomem;
+        struct imx_mu_priv *priv;
+        unsigned int i;
+        int ret;
+
+        priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+        if (!priv)
+                return -ENOMEM;
+
+        priv->dev = dev;
+
+        iomem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        priv->base = devm_ioremap_resource(&pdev->dev, iomem);
+        if (IS_ERR(priv->base))
+                return PTR_ERR(priv->base);
+
+        priv->irq = platform_get_irq(pdev, 0);
+        if (priv->irq < 0)
+                return priv->irq;
+
+        priv->clk = devm_clk_get(dev, NULL);
+        if (IS_ERR(priv->clk)) {
+                if (PTR_ERR(priv->clk) != -ENOENT)
+                        return PTR_ERR(priv->clk);
+
+                priv->clk = NULL;
+        }
+
+        ret = clk_prepare_enable(priv->clk);
+        if (ret) {
+                dev_err(dev, "Failed to enable clock\n");
+                return ret;
+        }
+
+        for (i = 0; i < IMX_MU_CHANS; i++) {
+                struct imx_mu_con_priv *cp = &priv->con_priv[i];
+
+                cp->idx = i % 4;
+                cp->type = i >> 2;
+                cp->chan = &priv->mbox_chans[i];
+                priv->mbox_chans[i].con_priv = cp;
+                snprintf(cp->irq_desc, sizeof(cp->irq_desc),
+                         "imx_mu_chan[%i-%i]", cp->type, cp->idx);
+        }
+
+        priv->side_b = of_property_read_bool(np, "fsl,mu-side-b");
+
+        spin_lock_init(&priv->xcr_lock);
+
+        priv->mbox.dev = dev;
+        priv->mbox.ops = &imx_mu_ops;
+        priv->mbox.chans = priv->mbox_chans;
+        priv->mbox.num_chans = IMX_MU_CHANS;
+        priv->mbox.of_xlate = imx_mu_xlate;
+        priv->mbox.txdone_irq = true;
+
+        platform_set_drvdata(pdev, priv);
+
+        imx_mu_init_generic(priv);
+
+        return mbox_controller_register(&priv->mbox);
+}
+
+static int imx_mu_remove(struct platform_device *pdev)
+{
+        struct imx_mu_priv *priv = platform_get_drvdata(pdev);
+
+        mbox_controller_unregister(&priv->mbox);
+        clk_disable_unprepare(priv->clk);
+
+        return 0;
+}
+
+static const struct of_device_id imx_mu_dt_ids[] = {
+        { .compatible = "fsl,imx6sx-mu" },
+        { },
+};
+MODULE_DEVICE_TABLE(of, imx_mu_dt_ids);
+
+static struct platform_driver imx_mu_driver = {
+        .probe          = imx_mu_probe,
+        .remove         = imx_mu_remove,
+        .driver = {
+                .name   = "imx_mu",
+                .of_match_table = imx_mu_dt_ids,
+        },
+};
+module_platform_driver(imx_mu_driver);
+
+MODULE_AUTHOR("Oleksij Rempel <o.rempel@pengutronix.de>");
+MODULE_DESCRIPTION("Message Unit driver for i.MX");
+MODULE_LICENSE("GPL v2");