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Date: Fri, 12 Dec 2014 08:38:33 -0600
From: Dinh Nguyen <dinh.linux@...il.com>
To: Ley Foon Tan <lftan@...era.com>,
Jassi Brar <jassisinghbrar@...il.com>,
linux-kernel@...r.kernel.org
CC: lftan.linux@...il.com, Suman Anna <s-anna@...com>,
devicetree@...r.kernel.org
Subject: Re: [PATCH (resend)] mailbox: Add Altera mailbox driver
On 12/12/14, 4:04 AM, Ley Foon Tan wrote:
> 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@...era.com>
> ---
> .../devicetree/bindings/mailbox/altera-mailbox.txt | 49 +++
> drivers/mailbox/Kconfig | 6 +
> drivers/mailbox/Makefile | 2 +
> drivers/mailbox/mailbox-altera.c | 404 +++++++++++++++++++++
> 4 files changed, 461 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/mailbox/altera-mailbox.txt
> create mode 100644 drivers/mailbox/mailbox-altera.c
>
> diff --git a/Documentation/devicetree/bindings/mailbox/altera-mailbox.txt b/Documentation/devicetree/bindings/mailbox/altera-mailbox.txt
> new file mode 100644
> index 0000000..c261979
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mailbox/altera-mailbox.txt
> @@ -0,0 +1,49 @@
> +Altera Mailbox Driver
> +=====================
> +
> +Required properties:
> +- compatible : "altr,mailbox-1.0".
> +- reg : physical base address of the mailbox and length of
> + memory mapped region.
> +- #mbox-cells: Common mailbox binding property to identify the number
> + of cells required for the mailbox specifier. Should be 1.
> +
> +Optional properties:
> +- interrupt-parent : interrupt source phandle.
> +- interrupts : interrupt number. The interrupt specifier format
> + depends on the interrupt controller parent.
> +
> +Example:
> + mbox_tx: mailbox@...00 {
> + compatible = "altr,mailbox-1.0";
> + reg = <0x100 0x8>;
> + interrupt-parent = < &gic_0 >;
> + interrupts = <5>;
> + #mbox-cells = <1>;
> + };
> +
> + mbox_rx: mailbox@...00 {
> + compatible = "altr,mailbox-1.0";
> + reg = <0x200 0x8>;
> + interrupt-parent = < &gic_0 >;
> + interrupts = <6>;
> + #mbox-cells = <1>;
> + };
> +
> +Mailbox client
> +===============
> +"mboxes" and the optional "mbox-names" (please see
> +Documentation/devicetree/bindings/mailbox/mailbox.txt for details). Each value
> +of the mboxes property should contain a phandle to the mailbox controller
> +device node and second argument is the channel index. It must be 0 (hardware
> +support only one channel).The equivalent "mbox-names" property value can be
> +used to give a name to the communication channel to be used by the client user.
> +
> +Example:
> + mclient0: mclient0@...00 {
> + compatible = "client-1.0";
> + reg = <0x400 0x10>;
> + mbox-names = "mbox-tx", "mbox-rx";
> + mboxes = <&mbox_tx 0>,
> + <&mbox_rx 0>;
> + };
> diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
> index c04fed9..84325f2 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 dd412c2..2e79231 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 0000000..9ed10de
> --- /dev/null
> +++ b/drivers/mailbox/mailbox-altera.c
> @@ -0,0 +1,404 @@
> +/*
> + * 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/kernel.h>
> +#include <linux/module.h>
> +#include <linux/device.h>
> +#include <linux/platform_device.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/of.h>
> +#include <linux/mailbox_controller.h>
Alphabetize the headers.
> +
> +#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 1 /* polling interval 1ms */
> +
> +struct altera_mbox {
> + bool is_sender; /* 1-sender, 0-receiver */
> + bool intr_mode;
> + int irq;
> + void __iomem *mbox_base;
> + struct device *dev;
> + struct mbox_chan chan;
> + struct mbox_controller controller;
> +
> + /* If the controller supports only RX polling mode */
> + struct timer_list rxpoll_timer;
> +};
> +
> +static inline struct altera_mbox *to_altera_mbox(struct mbox_chan *chan)
> +{
> + if (!chan)
> + return NULL;
> +
> + return container_of(chan, struct altera_mbox, chan);
> +}
> +
> +static inline int altera_mbox_full(struct altera_mbox *mbox)
> +{
> + u32 status;
> +
> + status = __raw_readl(mbox->mbox_base + MAILBOX_STS_REG);
> + return MBOX_FULL(status);
> +}
> +
> +static inline int altera_mbox_pending(struct altera_mbox *mbox)
> +{
> + u32 status;
> +
> + status = __raw_readl(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 = __raw_readl(mbox->mbox_base + MAILBOX_INTMASK_REG);
> + if (enable)
> + mask |= INT_PENDING_MSK;
> + else
> + mask &= ~INT_PENDING_MSK;
> + __raw_writel(mask, mbox->mbox_base + MAILBOX_INTMASK_REG);
> +}
> +
> +static void altera_mbox_tx_intmask(struct altera_mbox *mbox, bool enable)
> +{
> + u32 mask;
> +
> + mask = __raw_readl(mbox->mbox_base + MAILBOX_INTMASK_REG);
> + if (enable)
> + mask |= INT_SPACE_MSK;
> + else
> + mask &= ~INT_SPACE_MSK;
> + __raw_writel(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
> + __raw_writel(MBOX_MAGIC, mbox->mbox_base + MAILBOX_PTR_REG);
> + reg = __raw_readl(mbox->mbox_base + MAILBOX_PTR_REG);
> + if (reg == MBOX_MAGIC) {
> + /* Clear to 0 */
> + __raw_writel(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 = to_altera_mbox(chan);
> + u32 data[2];
> +
> + if (altera_mbox_pending(mbox)) {
> + data[MBOX_PTR] = __raw_readl(mbox->mbox_base + MAILBOX_PTR_REG);
> + data[MBOX_CMD] = __raw_readl(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 = 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 = 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 = to_altera_mbox(chan);
> +
> + if (mbox->intr_mode) {
> + ret = request_irq(mbox->irq, altera_mbox_tx_interrupt, 0,
Use devm_request_irq, since you didn't have and don't need use free_irq
in the shutdown function.
> + 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 = to_altera_mbox(chan);
> +
> + if (mbox->intr_mode) {
> + ret = request_irq(mbox->irq, altera_mbox_rx_interrupt, 0,
> + DRIVER_NAME, chan);
Use devm_request_irq
> + if (unlikely(ret)) {
> + dev_err(mbox->dev,
> + "failed to register mailbox interrupt:%d\n",
> + ret);
> + return ret;
> + }
> + altera_mbox_rx_intmask(mbox, true);
> + } else {
> + /* 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 = 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 */
> + altera_mbox_tx_intmask(mbox, true);
> +
> + /* Pointer register must write before command register */
> + __raw_writel(udata[MBOX_PTR], mbox->mbox_base + MAILBOX_PTR_REG);
> + __raw_writel(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 = to_altera_mbox(chan);
> +
> + if (WARN_ON(!mbox))
> + return false;
Are these checks necessary? Shouldn't the driver probe function have
already failed?
> +
> + /* 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 = to_altera_mbox(chan);
> +
> + if (WARN_ON(!mbox))
> + return false;
> +
> + return altera_mbox_pending(mbox) ? true : false;
> +}
> +
> +static int altera_mbox_startup(struct mbox_chan *chan)
> +{
> + struct altera_mbox *mbox = 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 = to_altera_mbox(chan);
> +
> + if (WARN_ON(!mbox))
> + return;
> +
> + if (mbox->intr_mode) {
> + /* Unmask all interrupt masks */
> + __raw_writel(~0, mbox->mbox_base + MAILBOX_INTMASK_REG);
> + free_irq(mbox->irq, chan);
> + } else if (!mbox->is_sender)
> + del_timer_sync(&mbox->rxpoll_timer);
Need braces around the else as well.
> +}
> +
> +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 mbox_chan *chans[1];
It would be cleaner if you use devm_kzalloc to allocate the channel here.
> + struct resource *regs;
> + int ret;
> +
> + mbox = devm_kzalloc(&pdev->dev, sizeof(struct altera_mbox),
> + GFP_KERNEL);
> + if (!mbox)
> + return -ENOMEM;
> +
> + regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!regs)
> + return -ENXIO;
> +
> + 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] = &mbox->chan;
> + mbox->controller.dev = mbox->dev;
> + mbox->controller.num_chans = 1;
> + mbox->controller.chans = &mbox->chan;
> + 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;
> + }
Need braces around the if as well.
> + }
> +
> + ret = mbox_controller_register(&mbox->controller);
> + if (ret) {
> + dev_err(&pdev->dev, "Register mailbox failed\n");
> + goto err;
> + }
> +
> + platform_set_drvdata(pdev, mbox);
> + return 0;
> +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);
> +
> + platform_set_drvdata(pdev, NULL);
> + 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,
> + .owner = THIS_MODULE,
> + .of_match_table = altera_mbox_match,
> + },
> +};
> +
> +static int altera_mbox_init(void)
> +{
> + return platform_driver_register(&altera_mbox_driver);
> +}
> +
> +static void altera_mbox_exit(void)
> +{
> + platform_driver_unregister(&altera_mbox_driver);
> +}
> +
> +module_init(altera_mbox_init);
> +module_exit(altera_mbox_exit);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("Altera mailbox specific functions");
> +MODULE_AUTHOR("Ley Foon Tan <lftan@...era.com>");
> +MODULE_ALIAS("platform:altera-mailbox");
>
Dinh
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