mailbox: Add Altera mailbox driver

The Altera mailbox allows for interprocessor communication. It supports
only one channel and work as either sender or receiver.

Signed-off-by: Ley Foon Tan <lftan@altera.com>

3 files changed, 396 insertions, 0 deletions

diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index c04fed9eb15d..84325f267acf 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -45,4 +45,10 @@ config PCC
           states). Select this driver if your platform implements the
           PCC clients mentioned above.
 
+config ALTERA_MBOX
+        tristate "Altera Mailbox"
+        help
+          An implementation of the Altera Mailbox soft core. It is used
+          to send message between processors. Say Y here if you want to use the
+          Altera mailbox support.
 endif
diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
index dd412c22208b..2e79231154cf 100644
--- a/drivers/mailbox/Makefile
+++ b/drivers/mailbox/Makefile
@@ -7,3 +7,5 @@ obj-$(CONFIG_PL320_MBOX)	+= pl320-ipc.o
 obj-$(CONFIG_OMAP2PLUS_MBOX)    += omap-mailbox.o
 
 obj-$(CONFIG_PCC)               += pcc.o
+
+obj-$(CONFIG_ALTERA_MBOX)       += mailbox-altera.o
diff --git a/drivers/mailbox/mailbox-altera.c b/drivers/mailbox/mailbox-altera.c
new file mode 100644
index 000000000000..a266265677d3
--- /dev/null
+++ b/drivers/mailbox/mailbox-altera.c
@@ -0,0 +1,388 @@
+/*
+ * Copyright Altera Corporation (C) 2013-2014. All rights reserved
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/device.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.h>
+#include <linux/platform_device.h>
+
+#define DRIVER_NAME     "altera-mailbox"
+
+#define MAILBOX_CMD_REG                 0x00
+#define MAILBOX_PTR_REG                 0x04
+#define MAILBOX_STS_REG                 0x08
+#define MAILBOX_INTMASK_REG             0x0C
+
+#define INT_PENDING_MSK                 0x1
+#define INT_SPACE_MSK                   0x2
+
+#define STS_PENDING_MSK                 0x1
+#define STS_FULL_MSK                    0x2
+#define STS_FULL_OFT                    0x1
+
+#define MBOX_PENDING(status)    (((status) & STS_PENDING_MSK))
+#define MBOX_FULL(status)       (((status) & STS_FULL_MSK) >> STS_FULL_OFT)
+
+enum altera_mbox_msg {
+        MBOX_CMD = 0,
+        MBOX_PTR,
+};
+
+#define MBOX_POLLING_MS         5       /* polling interval 5ms */
+
+struct altera_mbox {
+        bool is_sender;         /* 1-sender, 0-receiver */
+        bool intr_mode;
+        int irq;
+        void __iomem *mbox_base;
+        struct device *dev;
+        struct mbox_controller controller;
+
+        /* If the controller supports only RX polling mode */
+        struct timer_list rxpoll_timer;
+};
+
+static struct altera_mbox *mbox_chan_to_altera_mbox(struct mbox_chan *chan)
+{
+        if (!chan || !chan->con_priv)
+                return NULL;
+
+        return (struct altera_mbox *)chan->con_priv;
+}
+
+static inline int altera_mbox_full(struct altera_mbox *mbox)
+{
+        u32 status;
+
+        status = readl_relaxed(mbox->mbox_base + MAILBOX_STS_REG);
+        return MBOX_FULL(status);
+}
+
+static inline int altera_mbox_pending(struct altera_mbox *mbox)
+{
+        u32 status;
+
+        status = readl_relaxed(mbox->mbox_base + MAILBOX_STS_REG);
+        return MBOX_PENDING(status);
+}
+
+static void altera_mbox_rx_intmask(struct altera_mbox *mbox, bool enable)
+{
+        u32 mask;
+
+        mask = readl_relaxed(mbox->mbox_base + MAILBOX_INTMASK_REG);
+        if (enable)
+                mask |= INT_PENDING_MSK;
+        else
+                mask &= ~INT_PENDING_MSK;
+        writel_relaxed(mask, mbox->mbox_base + MAILBOX_INTMASK_REG);
+}
+
+static void altera_mbox_tx_intmask(struct altera_mbox *mbox, bool enable)
+{
+        u32 mask;
+
+        mask = readl_relaxed(mbox->mbox_base + MAILBOX_INTMASK_REG);
+        if (enable)
+                mask |= INT_SPACE_MSK;
+        else
+                mask &= ~INT_SPACE_MSK;
+        writel_relaxed(mask, mbox->mbox_base + MAILBOX_INTMASK_REG);
+}
+
+static bool altera_mbox_is_sender(struct altera_mbox *mbox)
+{
+        u32 reg;
+        /* Write a magic number to PTR register and read back this register.
+         * This register is read-write if it is a sender.
+         */
+        #define MBOX_MAGIC      0xA5A5AA55
+        writel_relaxed(MBOX_MAGIC, mbox->mbox_base + MAILBOX_PTR_REG);
+        reg = readl_relaxed(mbox->mbox_base + MAILBOX_PTR_REG);
+        if (reg == MBOX_MAGIC) {
+                /* Clear to 0 */
+                writel_relaxed(0, mbox->mbox_base + MAILBOX_PTR_REG);
+                return true;
+        }
+        return false;
+}
+
+static void altera_mbox_rx_data(struct mbox_chan *chan)
+{
+        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
+        u32 data[2];
+
+        if (altera_mbox_pending(mbox)) {
+                data[MBOX_PTR] =
+                        readl_relaxed(mbox->mbox_base + MAILBOX_PTR_REG);
+                data[MBOX_CMD] =
+                        readl_relaxed(mbox->mbox_base + MAILBOX_CMD_REG);
+                mbox_chan_received_data(chan, (void *)data);
+        }
+}
+
+static void altera_mbox_poll_rx(unsigned long data)
+{
+        struct mbox_chan *chan = (struct mbox_chan *)data;
+        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
+
+        altera_mbox_rx_data(chan);
+
+        mod_timer(&mbox->rxpoll_timer,
+                  jiffies + msecs_to_jiffies(MBOX_POLLING_MS));
+}
+
+static irqreturn_t altera_mbox_tx_interrupt(int irq, void *p)
+{
+        struct mbox_chan *chan = (struct mbox_chan *)p;
+        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
+
+        altera_mbox_tx_intmask(mbox, false);
+        mbox_chan_txdone(chan, 0);
+
+        return IRQ_HANDLED;
+}
+
+static irqreturn_t altera_mbox_rx_interrupt(int irq, void *p)
+{
+        struct mbox_chan *chan = (struct mbox_chan *)p;
+
+        altera_mbox_rx_data(chan);
+        return IRQ_HANDLED;
+}
+
+static int altera_mbox_startup_sender(struct mbox_chan *chan)
+{
+        int ret;
+        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
+
+        if (mbox->intr_mode) {
+                ret = request_irq(mbox->irq, altera_mbox_tx_interrupt, 0,
+                                  DRIVER_NAME, chan);
+                if (unlikely(ret)) {
+                        dev_err(mbox->dev,
+                                "failed to register mailbox interrupt:%d\n",
+                                ret);
+                        return ret;
+                }
+        }
+
+        return 0;
+}
+
+static int altera_mbox_startup_receiver(struct mbox_chan *chan)
+{
+        int ret;
+        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
+
+        if (mbox->intr_mode) {
+                ret = request_irq(mbox->irq, altera_mbox_rx_interrupt, 0,
+                                  DRIVER_NAME, chan);
+                if (unlikely(ret)) {
+                        mbox->intr_mode = false;
+                        goto polling; /* use polling if failed */
+                }
+
+                altera_mbox_rx_intmask(mbox, true);
+                return 0;
+        }
+
+polling:
+        /* Setup polling timer */
+        setup_timer(&mbox->rxpoll_timer, altera_mbox_poll_rx,
+                    (unsigned long)chan);
+        mod_timer(&mbox->rxpoll_timer,
+                  jiffies + msecs_to_jiffies(MBOX_POLLING_MS));
+
+        return 0;
+}
+
+static int altera_mbox_send_data(struct mbox_chan *chan, void *data)
+{
+        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
+        u32 *udata = (u32 *)data;
+
+        if (!mbox || !data)
+                return -EINVAL;
+        if (!mbox->is_sender) {
+                dev_warn(mbox->dev,
+                         "failed to send. This is receiver mailbox.\n");
+                return -EINVAL;
+        }
+
+        if (altera_mbox_full(mbox))
+                return -EBUSY;
+
+        /* Enable interrupt before send */
+        if (mbox->intr_mode)
+                altera_mbox_tx_intmask(mbox, true);
+
+        /* Pointer register must write before command register */
+        writel_relaxed(udata[MBOX_PTR], mbox->mbox_base + MAILBOX_PTR_REG);
+        writel_relaxed(udata[MBOX_CMD], mbox->mbox_base + MAILBOX_CMD_REG);
+
+        return 0;
+}
+
+static bool altera_mbox_last_tx_done(struct mbox_chan *chan)
+{
+        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
+
+        /* Return false if mailbox is full */
+        return altera_mbox_full(mbox) ? false : true;
+}
+
+static bool altera_mbox_peek_data(struct mbox_chan *chan)
+{
+        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
+
+        return altera_mbox_pending(mbox) ? true : false;
+}
+
+static int altera_mbox_startup(struct mbox_chan *chan)
+{
+        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
+        int ret = 0;
+
+        if (!mbox)
+                return -EINVAL;
+
+        if (mbox->is_sender)
+                ret = altera_mbox_startup_sender(chan);
+        else
+                ret = altera_mbox_startup_receiver(chan);
+
+        return ret;
+}
+
+static void altera_mbox_shutdown(struct mbox_chan *chan)
+{
+        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
+
+        if (mbox->intr_mode) {
+                /* Unmask all interrupt masks */
+                writel_relaxed(~0, mbox->mbox_base + MAILBOX_INTMASK_REG);
+                free_irq(mbox->irq, chan);
+        } else if (!mbox->is_sender) {
+                del_timer_sync(&mbox->rxpoll_timer);
+        }
+}
+
+static struct mbox_chan_ops altera_mbox_ops = {
+        .send_data = altera_mbox_send_data,
+        .startup = altera_mbox_startup,
+        .shutdown = altera_mbox_shutdown,
+        .last_tx_done = altera_mbox_last_tx_done,
+        .peek_data = altera_mbox_peek_data,
+};
+
+static int altera_mbox_probe(struct platform_device *pdev)
+{
+        struct altera_mbox *mbox;
+        struct resource *regs;
+        struct mbox_chan *chans;
+        int ret;
+
+        mbox = devm_kzalloc(&pdev->dev, sizeof(*mbox),
+                            GFP_KERNEL);
+        if (!mbox)
+                return -ENOMEM;
+
+        /* Allocated one channel */
+        chans = devm_kzalloc(&pdev->dev, sizeof(*chans), GFP_KERNEL);
+        if (!chans)
+                return -ENOMEM;
+
+        regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+        mbox->mbox_base = devm_ioremap_resource(&pdev->dev, regs);
+        if (IS_ERR(mbox->mbox_base))
+                return PTR_ERR(mbox->mbox_base);
+
+        /* Check is it a sender or receiver? */
+        mbox->is_sender = altera_mbox_is_sender(mbox);
+
+        mbox->irq = platform_get_irq(pdev, 0);
+        if (mbox->irq >= 0)
+                mbox->intr_mode = true;
+
+        mbox->dev = &pdev->dev;
+
+        /* Hardware supports only one channel. */
+        chans[0].con_priv = mbox;
+        mbox->controller.dev = mbox->dev;
+        mbox->controller.num_chans = 1;
+        mbox->controller.chans = chans;
+        mbox->controller.ops = &altera_mbox_ops;
+
+        if (mbox->is_sender) {
+                if (mbox->intr_mode) {
+                        mbox->controller.txdone_irq = true;
+                } else {
+                        mbox->controller.txdone_poll = true;
+                        mbox->controller.txpoll_period = MBOX_POLLING_MS;
+                }
+        }
+
+        ret = mbox_controller_register(&mbox->controller);
+        if (ret) {
+                dev_err(&pdev->dev, "Register mailbox failed\n");
+                goto err;
+        }
+
+        platform_set_drvdata(pdev, mbox);
+err:
+        return ret;
+}
+
+static int altera_mbox_remove(struct platform_device *pdev)
+{
+        struct altera_mbox *mbox = platform_get_drvdata(pdev);
+
+        if (!mbox)
+                return -EINVAL;
+
+        mbox_controller_unregister(&mbox->controller);
+
+        return 0;
+}
+
+static const struct of_device_id altera_mbox_match[] = {
+        { .compatible = "altr,mailbox-1.0" },
+        { /* Sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, altera_mbox_match);
+
+static struct platform_driver altera_mbox_driver = {
+        .probe  = altera_mbox_probe,
+        .remove = altera_mbox_remove,
+        .driver = {
+                .name   = DRIVER_NAME,
+                .of_match_table = altera_mbox_match,
+        },
+};
+
+module_platform_driver(altera_mbox_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Altera mailbox specific functions");
+MODULE_AUTHOR("Ley Foon Tan <lftan@altera.com>");
+MODULE_ALIAS("platform:altera-mailbox");