Re: [PATCHv2 2/2] mailbox: Adding driver for Xilinx LogiCORE IP mailbox.
From: Michal Simek
Date: Thu May 28 2015 - 01:45:40 EST
On 05/27/2015 08:35 PM, Moritz Fischer wrote:
> The Xilinx LogiCORE IP mailbox is a FPGA core that allows for
> interprocessor communication via AXI4 memory mapped / AXI4 stream
> interfaces.
>
> It is single channel per core and allows for transmit and receive.
>
> Changes from v1:
> - Added common clock framework support
> - Deal with IRQs that happend before driver load,
> since HW will not let us know about them when we enable IRQs
>
> Changes from v0:
> - Several stylistic issues
> - Dropped superfluous intr_mode member
> - Really masking the IRQs on mailbox_shutdown
> - No longer using polling by accident in non-IRQ mode
> - Swapped doc and driver commits
>
> Signed-off-by: Moritz Fischer <moritz.fischer@xxxxxxxxx>
> ---
> MAINTAINERS | 7 +
> drivers/mailbox/Kconfig | 8 +
> drivers/mailbox/Makefile | 2 +
> drivers/mailbox/mailbox-xilinx.c | 349 ++++++++++++++++++++++++++++++++++
> 4 files changed, 366 insertions(+)
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index f8e0afb..f1f0d10 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -10986,6 +10986,13 @@ M: John Linn <John.Linn@xxxxxxxxxx>
> S: Maintained
> F: drivers/net/ethernet/xilinx/xilinx_axienet*
>
> +XILINX MAILBOX DRIVER
> +M: Moritz Fischer <moritz.fischer@xxxxxxxxx>
> +L: linux-kernel@xxxxxxxxxxxxxxx
> +S: Maintained
> +F: drivers/mailbox/mailbox-xilinx.c
> +F: Documentation/devicetree/bindings/mailbox/xilinx-mailbox.txt
> +
> XILINX UARTLITE SERIAL DRIVER
> M: Peter Korsgaard <jacmet@xxxxxxxxxx>
> L: linux-serial@xxxxxxxxxxxxxxx
> diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
> index 84b0a2d..e11e4b2 100644
> --- a/drivers/mailbox/Kconfig
> +++ b/drivers/mailbox/Kconfig
> @@ -60,4 +60,12 @@ config ALTERA_MBOX
> 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.
> +
> +config XILINX_MBOX
> + tristate "Xilinx Mailbox"
> + help
> + An implementation of the Xilinx Mailbox soft core. It is used
> + to send message between processors. Say Y here if you want to use the
> + Xilinx mailbox support.
> +
> endif
> diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
> index b18201e..d28a028 100644
> --- a/drivers/mailbox/Makefile
> +++ b/drivers/mailbox/Makefile
> @@ -11,3 +11,5 @@ obj-$(CONFIG_OMAP2PLUS_MBOX) += omap-mailbox.o
> obj-$(CONFIG_PCC) += pcc.o
>
> obj-$(CONFIG_ALTERA_MBOX) += mailbox-altera.o
> +
> +obj-$(CONFIG_XILINX_MBOX) += mailbox-xilinx.o
> diff --git a/drivers/mailbox/mailbox-xilinx.c b/drivers/mailbox/mailbox-xilinx.c
> new file mode 100644
> index 0000000..fd1cdf2
> --- /dev/null
> +++ b/drivers/mailbox/mailbox-xilinx.c
> @@ -0,0 +1,349 @@
> +/*
> + * Copyright (c) 2015, National Instruments Corp. All rights reserved.
> + *
> + * Driver for the Xilinx LogiCORE mailbox IP block
> + *
> + * 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/clk.h>
> +#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 "xilinx-mailbox"
> +
> +/* register offsets */
> +#define MAILBOX_REG_WRDATA 0x00
> +#define MAILBOX_REG_RDDATA 0x08
> +#define MAILBOX_REG_STATUS 0x10
> +#define MAILBOX_REG_ERROR 0x14
> +#define MAILBOX_REG_SIT 0x18
> +#define MAILBOX_REG_RIT 0x1c
> +#define MAILBOX_REG_IS 0x20
> +#define MAILBOX_REG_IE 0x24
> +#define MAILBOX_REG_IP 0x28
> +
> +/* status register */
> +#define STS_RTA BIT(3)
> +#define STS_STA BIT(2)
> +#define STS_FULL BIT(1)
> +#define STS_EMPTY BIT(0)
> +
> +/* error register */
> +#define ERR_FULL BIT(1)
> +#define ERR_EMPTY BIT(0)
> +
> +/* mailbox interrupt status register */
> +#define INT_STATUS_ERR BIT(2)
> +#define INT_STATUS_RTI BIT(1)
> +#define INT_STATUS_STI BIT(0)
> +
> +/* mailbox interrupt enable register */
> +#define INT_ENABLE_ERR BIT(2)
> +#define INT_ENABLE_RTI BIT(1)
> +#define INT_ENABLE_STI BIT(0)
> +
> +#define MBOX_POLLING_MS 5 /* polling interval 5ms */
> +
> +struct xilinx_mbox {
> + int irq;
> + void __iomem *mbox_base;
> + struct clk *clk;
> + struct device *dev;
> + struct mbox_controller controller;
> +
> + /* if the controller supports only RX polling mode */
> + struct timer_list rxpoll_timer;
> +};
> +
> +static struct xilinx_mbox *mbox_chan_to_xilinx_mbox(struct mbox_chan *chan)
> +{
> + if (!chan || !chan->con_priv)
> + return NULL;
> +
> + return (struct xilinx_mbox *)chan->con_priv;
> +}
> +
> +static inline bool xilinx_mbox_full(struct xilinx_mbox *mbox)
> +{
> + u32 status;
> +
> + status = readl_relaxed(mbox->mbox_base + MAILBOX_REG_STATUS);
> +
> + return status & STS_FULL;
> +}
> +
> +static inline bool xilinx_mbox_pending(struct xilinx_mbox *mbox)
> +{
> + u32 status;
> +
> + status = readl_relaxed(mbox->mbox_base + MAILBOX_REG_STATUS);
> +
> + return !(status & STS_EMPTY);
> +}
> +
> +static void xilinx_mbox_intmask(struct xilinx_mbox *mbox, u32 mask, bool enable)
> +{
> + u32 mask_reg;
> +
> + mask_reg = readl_relaxed(mbox->mbox_base + MAILBOX_REG_IE);
> + if (enable)
> + mask_reg |= mask;
> + else
> + mask_reg &= ~mask;
> + writel_relaxed(mask_reg, mbox->mbox_base + MAILBOX_REG_IE);
> +}
> +
> +
> +static inline void xilinx_mbox_rx_intmask(struct xilinx_mbox *mbox, bool enable)
> +{
> + xilinx_mbox_intmask(mbox, INT_ENABLE_RTI, enable);
> +}
> +
> +static inline void xilinx_mbox_tx_intmask(struct xilinx_mbox *mbox, bool enable)
> +{
> + xilinx_mbox_intmask(mbox, INT_ENABLE_STI, enable);
> +}
> +
> +static void xilinx_mbox_rx_data(struct mbox_chan *chan)
> +{
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> + u32 data;
> +
> + if (xilinx_mbox_pending(mbox)) {
> + data = readl_relaxed(mbox->mbox_base + MAILBOX_REG_RDDATA);
> + mbox_chan_received_data(chan, (void *)data);
> + }
> +}
> +
> +static void xilinx_mbox_poll_rx(unsigned long data)
> +{
> + struct mbox_chan *chan = (struct mbox_chan *)data;
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> +
> + xilinx_mbox_rx_data(chan);
> +
> + mod_timer(&mbox->rxpoll_timer,
> + jiffies + msecs_to_jiffies(MBOX_POLLING_MS));
> +}
> +
> +static irqreturn_t xilinx_mbox_interrupt(int irq, void *p)
> +{
> + u32 mask;
> + struct mbox_chan *chan = (struct mbox_chan *)p;
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> +
> + mask = readl_relaxed(mbox->mbox_base + MAILBOX_REG_IS);
> + if (mask & INT_STATUS_RTI)
> + xilinx_mbox_rx_data(chan);
> +
> + /* mask irqs *before* notifying done, require tx_block=true */
> + if (mask & INT_STATUS_STI) {
> + xilinx_mbox_tx_intmask(mbox, false);
> + mbox_chan_txdone(chan, 0);
> + }
> +
> + writel_relaxed(mask, mbox->mbox_base + MAILBOX_REG_IS);
empty line here please.
> + return IRQ_HANDLED;
> +}
> +
> +static int xilinx_mbox_startup(struct mbox_chan *chan)
> +{
> + int ret;
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> +
> + if (mbox->irq >= 0) {
> + ret = request_irq(mbox->irq, xilinx_mbox_interrupt, 0,
> + dev_name(mbox->dev), chan);
> + if (unlikely(ret)) {
> + dev_err(mbox->dev,
> + "failed to register mailbox interrupt:%d\n",
> + ret);
> + goto polling; /* use polling if failed */
This is the problematic path. For case that request_irq failed - you are
using polling mode but in shutdown below mbox_irq > 0 and you will
free_irq not call del_timer_sync.
I understand that you want to be smart here but it should be enough just
to return error here and you are done. But up2you I expect that this
path wasn't tested.
> + }
> +
> + xilinx_mbox_rx_intmask(mbox, true);
> +
> + /* if fifo was full already, we didn't get an interrupt */
> + while (xilinx_mbox_pending(mbox))
> + xilinx_mbox_rx_data(chan);
> +
> + return 0;
> + }
> +
> +polling:
> + /* setup polling timer */
> + setup_timer(&mbox->rxpoll_timer, xilinx_mbox_poll_rx,
> + (unsigned long)chan);
> + mod_timer(&mbox->rxpoll_timer,
> + jiffies + msecs_to_jiffies(MBOX_POLLING_MS));
> +
> + return 0;
> +}
> +
> +static int xilinx_mbox_send_data(struct mbox_chan *chan, void *data)
> +{
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> + u32 *udata = (u32 *)data;
> +
> + if (!mbox || !data)
> + return -EINVAL;
> +
> + if (xilinx_mbox_full(mbox))
> + return -EBUSY;
> +
> + /* enable interrupt before send */
> + if (mbox->irq >= 0)
> + xilinx_mbox_tx_intmask(mbox, true);
> +
> + writel_relaxed(*udata, mbox->mbox_base + MAILBOX_REG_WRDATA);
> +
> + return 0;
> +}
> +
> +static bool xilinx_mbox_last_tx_done(struct mbox_chan *chan)
> +{
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> +
> + /* return false if mailbox is full */
> + return !xilinx_mbox_full(mbox);
> +}
> +
> +static bool xilinx_mbox_peek_data(struct mbox_chan *chan)
> +{
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> +
> + return xilinx_mbox_pending(mbox);
> +}
> +
> +static void xilinx_mbox_shutdown(struct mbox_chan *chan)
> +{
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> +
> + if (mbox->irq >= 0) {
look below.
> + /* mask all interrupts */
> + writel_relaxed(0, mbox->mbox_base + MAILBOX_REG_IE);
> + free_irq(mbox->irq, chan);
> + } else {
> + del_timer_sync(&mbox->rxpoll_timer);
> + }
> +}
> +
> +static struct mbox_chan_ops xilinx_mbox_ops = {
> + .send_data = xilinx_mbox_send_data,
> + .startup = xilinx_mbox_startup,
> + .shutdown = xilinx_mbox_shutdown,
> + .last_tx_done = xilinx_mbox_last_tx_done,
> + .peek_data = xilinx_mbox_peek_data,
> +};
> +
> +static int xilinx_mbox_probe(struct platform_device *pdev)
> +{
> + struct xilinx_mbox *mbox;
> + struct resource *regs;
> + struct mbox_chan *chans;
> + int ret;
> +
> + mbox = devm_kzalloc(&pdev->dev, sizeof(*mbox), GFP_KERNEL);
> + if (!mbox)
> + return -ENOMEM;
> +
> + /* get clk and enable */
> + mbox->clk = devm_clk_get(&pdev->dev, "mbox");
> + clk_prepare_enable(mbox->clk);
huh you should probably check error first before enabling.
Also if you call enable there, you should also call
clk_disable_unprepare when any error here happen.
Probably make sense to move this clock enabling below.
> + if (IS_ERR(mbox->clk)) {
> + dev_err(&pdev->dev, "Couldn't get clk.\n");
> + return PTR_ERR(mbox->clk);
> + }
> +
> + /* 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);
> +
> + mbox->irq = platform_get_irq(pdev, 0);
> + /* if irq is present, we can use it, otherwise, poll */
> + if (mbox->irq >= 0)
0 also suggest error - it means here should be just > 0;
> + mbox->controller.txdone_irq = true;
missing {} around if - look at coding style guide
> + else {
> + dev_info(&pdev->dev, "IRQ not found, fallback to polling.\n");
> + mbox->controller.txdone_poll = true;
> + mbox->controller.txpoll_period = MBOX_POLLING_MS;
> + }
> +
> + 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 = &xilinx_mbox_ops;
> +
> + ret = mbox_controller_register(&mbox->controller);
> + if (ret) {
> + dev_err(&pdev->dev, "Register mailbox failed\n");
> + return ret;
> + }
> +
> + platform_set_drvdata(pdev, mbox);
> +
> + return 0;
> +}
> +
> +
remove this one empty line.
> +static int xilinx_mbox_remove(struct platform_device *pdev)
> +{
> + struct xilinx_mbox *mbox = platform_get_drvdata(pdev);
> +
> + if (!mbox)
> + return -EINVAL;
> +
> + mbox_controller_unregister(&mbox->controller);
> +
> + clk_disable_unprepare(mbox->clk);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id xilinx_mbox_match[] = {
> + { .compatible = "xlnx,mailbox-2.1" },
> + { /* sentinel */ }
> +};
> +
> +MODULE_DEVICE_TABLE(of, xilinx_mbox_match);
> +
> +static struct platform_driver xilinx_mbox_driver = {
> + .probe = xilinx_mbox_probe,
> + .remove = xilinx_mbox_remove,
> + .driver = {
> + .name = DRIVER_NAME,
> + .of_match_table = xilinx_mbox_match,
> + },
> +};
> +
> +module_platform_driver(xilinx_mbox_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("Xilinx mailbox specific functions");
> +MODULE_AUTHOR("Moritz Fischer <moritz.fischer@xxxxxxxxx>");
> +MODULE_ALIAS("platform:xilinx-mailbox");
>
Thanks,
Michal
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