Re: [PATCH v5 1/3] mailbox: Add support for APM X-Gene platform mailbox driver

From: Duc Dang <dhdang@apm.com>
To: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Jassi Brar <jassisinghbrar@gmail.com>,
	Rob Herring <robh@kernel.org>, Paul Bolle <pebolle@tiscali.nl>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	patches <patches@apm.com>, Feng Kan <fkan@apm.com>
Subject: Re: [PATCH v5 1/3] mailbox: Add support for APM X-Gene platform mailbox driver
Date: Fri, 12 Feb 2016 19:25:20 -0800	[thread overview]
Message-ID: <CADaLNDmVFG1xLV9fM16+2bL+F0enEDX1Pc9d71Tmw_-n=RSmwA@mail.gmail.com> (raw)
In-Reply-To: <CANLsYkxPnFCuJLyKsHnXKdbvAwNurtgQgJ-WF+bD26+8EjkfJw@mail.gmail.com>

On Wed, Feb 10, 2016 at 6:41 AM, Mathieu Poirier
<mathieu.poirier@linaro.org> wrote:
> On 9 February 2016 at 20:46, Duc Dang <dhdang@apm.com> wrote:
>> On Tue, Feb 9, 2016 at 8:40 AM, Mathieu Poirier
>> <mathieu.poirier@linaro.org> wrote:
>>> On 8 February 2016 at 15:04, Duc Dang <dhdang@apm.com> wrote:
>>>> X-Gene mailbox controller provides 8 mailbox channels, with
>>>> each channel has a dedicated interrupt line.
>>>>
>>>> Signed-off-by: Feng Kan <fkan@apm.com>
>>>> Signed-off-by: Duc Dang <dhdang@apm.com>
>>>> ---
>>>> Changes since v4:
>>>>         - Rebase over v4.5-rc1
>>>>         - Fix section mistmatch warning by removing
>>>>         __init in slimpro_mbox_probe declaration
>>>>         - Correctly print channel number when
>>>>         there is no IRQ for that channel
>>>>
>>>> Changes since v3:
>>>>         - Rebase over v4.4
>>>>         - Remove 'id' in slimpro_mbox_chan structure
>>>>         - Remove small functions that are only called once
>>>>         and fold them into the other callers
>>>>         - Remove void* pointer type cast
>>>>         - Relax the number of mailbox IRQs condition
>>>>         - Use subsys_initcall to guarantee mailbox driver
>>>>         will be registered before any other dependent driver
>>>>         is loaded.
>>>>
>>>>  drivers/mailbox/Kconfig                 |   9 ++
>>>>  drivers/mailbox/Makefile                |   2 +
>>>>  drivers/mailbox/mailbox-xgene-slimpro.c | 264 ++++++++++++++++++++++++++++++++
>>>>  3 files changed, 275 insertions(+)
>>>>  create mode 100644 drivers/mailbox/mailbox-xgene-slimpro.c
>>>>
>>>> diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
>>>> index 546d05f..678e434 100644
>>>> --- a/drivers/mailbox/Kconfig
>>>> +++ b/drivers/mailbox/Kconfig
>>>> @@ -85,4 +85,13 @@ config MAILBOX_TEST
>>>>           Test client to help with testing new Controller driver
>>>>           implementations.
>>>>
>>>> +config XGENE_SLIMPRO_MBOX
>>>> +       tristate "APM SoC X-Gene SLIMpro Mailbox Controller"
>>>> +       depends on ARCH_XGENE
>>>> +       help
>>>> +         An implementation of the APM X-Gene Interprocessor Communication
>>>> +         Mailbox (IPCM) between the ARM 64-bit cores and SLIMpro controller.
>>>> +         It is used to send short messages between ARM64-bit cores and
>>>> +         the SLIMpro Management Engine, primarily for PM. Say Y here if you
>>>> +         want to use the APM X-Gene SLIMpro IPCM support.
>>>>  endif
>>>> diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
>>>> index 92435ef..b602ef8 100644
>>>> --- a/drivers/mailbox/Makefile
>>>> +++ b/drivers/mailbox/Makefile
>>>> @@ -17,3 +17,5 @@ obj-$(CONFIG_ALTERA_MBOX)     += mailbox-altera.o
>>>>  obj-$(CONFIG_BCM2835_MBOX)     += bcm2835-mailbox.o
>>>>
>>>>  obj-$(CONFIG_STI_MBOX)         += mailbox-sti.o
>>>> +
>>>> +obj-$(CONFIG_XGENE_SLIMPRO_MBOX) += mailbox-xgene-slimpro.o
>>>> diff --git a/drivers/mailbox/mailbox-xgene-slimpro.c b/drivers/mailbox/mailbox-xgene-slimpro.c
>>>> new file mode 100644
>>>> index 0000000..0ea1eb8
>>>> --- /dev/null
>>>> +++ b/drivers/mailbox/mailbox-xgene-slimpro.c
>>>> @@ -0,0 +1,264 @@
>>>> +/*
>>>> + * APM X-Gene SLIMpro MailBox Driver
>>>> + *
>>>> + * Copyright (c) 2015, Applied Micro Circuits Corporation
>>>> + * Author: Feng Kan fkan@apm.com
>>>> + *
>>>> + * 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; either version 2 of
>>>> + * the License, or (at your option) any later version.
>>>> + *
>>>> + * 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.
>>>> + *
>>>> + * 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/acpi.h>
>>>> +#include <linux/delay.h>
>>>> +#include <linux/interrupt.h>
>>>> +#include <linux/io.h>
>>>> +#include <linux/mailbox_controller.h>
>>>> +#include <linux/module.h>
>>>> +#include <linux/of.h>
>>>> +#include <linux/platform_device.h>
>>>> +#include <linux/spinlock.h>
>>>> +
>>>> +#define MBOX_CON_NAME                  "slimpro-mbox"
>>>> +#define MBOX_REG_SET_OFFSET            0x1000
>>>> +#define MBOX_CNT                       8
>>>> +#define MBOX_STATUS_AVAIL_MASK         BIT(16)
>>>> +#define MBOX_STATUS_ACK_MASK           BIT(0)
>>>> +
>>>> +/* Configuration and Status Registers */
>>>> +#define REG_DB_IN              0x00
>>>> +#define REG_DB_DIN0            0x04
>>>> +#define REG_DB_DIN1            0x08
>>>> +#define REG_DB_OUT             0x10
>>>> +#define REG_DB_DOUT0           0x14
>>>> +#define REG_DB_DOUT1           0x18
>>>> +#define REG_DB_STAT            0x20
>>>> +#define REG_DB_STATMASK                0x24
>>>> +
>>>> +struct slimpro_mbox_chan {
>>>> +       struct device *dev;
>>>> +       struct mbox_chan *chan;
>>>> +       void __iomem *reg;
>>>> +       int irq;
>>>> +       u32 rx_msg[3];
>>>> +};
>>>> +
>>>> +struct slimpro_mbox {
>>>> +       struct mbox_controller mb_ctrl;
>>>> +       struct slimpro_mbox_chan mc[MBOX_CNT];
>>>> +       struct mbox_chan chans[MBOX_CNT];
>>>> +};
>>>
>>> The above two structure declaration could use kernel style documentation.
>>
>> Can you please clarify or give an example? I looked into several files
>> in drivers/mailbox/ and drivers/irqchip but could not find what I need
>> to tweak.
>
> http://lxr.free-electrons.com/source/drivers/mailbox/mailbox-sti.c#L42

I am modifying the structure defintion to add description and will
post a new version shortly.

Regards,
Duc Dang.
>
>>
>>>
>>>> +
>>>> +static void mb_chan_send_msg(struct slimpro_mbox_chan *mb_chan, u32 *msg)
>>>> +{
>>>> +       writel(msg[1], mb_chan->reg + REG_DB_DOUT0);
>>>> +       writel(msg[2], mb_chan->reg + REG_DB_DOUT1);
>>>> +       writel(msg[0], mb_chan->reg + REG_DB_OUT);
>>>> +}
>>>> +
>>>> +static void mb_chan_recv_msg(struct slimpro_mbox_chan *mb_chan)
>>>> +{
>>>> +       mb_chan->rx_msg[1] = readl(mb_chan->reg + REG_DB_DIN0);
>>>> +       mb_chan->rx_msg[2] = readl(mb_chan->reg + REG_DB_DIN1);
>>>> +       mb_chan->rx_msg[0] = readl(mb_chan->reg + REG_DB_IN);
>>>> +}
>>>
>>> Is there a requirement that operations in the above two functions be
>>> ordered?  If not significant gains could be achieved by using
>>> writel/readl_relaxed().  Same comment for the rest of this driver.
>>
>> The 'writes' need to be in order as writing to REG_DB_OUT will trigger
>> interrupt, so I want the other 2 'writes' complete before it.
>>
>> After the receiver get the message, it will clear door bell available
>> interrupt request, this will also trigger a door bell acknowledge
>> interrupt. So the 'read' to get the message and the 'write' to clear
>> the door bell available interrupt must be in order as well.
>>
>> Regards,
>> Duc Dang.
>>>
>>> Thanks,
>>> Mathieu
>>>
>>>> +
>>>> +static int mb_chan_status_ack(struct slimpro_mbox_chan *mb_chan)
>>>> +{
>>>> +       u32 val = readl(mb_chan->reg + REG_DB_STAT);
>>>> +
>>>> +       if (val & MBOX_STATUS_ACK_MASK) {
>>>> +               writel(MBOX_STATUS_ACK_MASK, mb_chan->reg + REG_DB_STAT);
>>>> +               return 1;
>>>> +       }
>>>> +       return 0;
>>>> +}
>>>> +
>>>> +static int mb_chan_status_avail(struct slimpro_mbox_chan *mb_chan)
>>>> +{
>>>> +       u32 val = readl(mb_chan->reg + REG_DB_STAT);
>>>> +
>>>> +       if (val & MBOX_STATUS_AVAIL_MASK) {
>>>> +               mb_chan_recv_msg(mb_chan);
>>>> +               writel(MBOX_STATUS_AVAIL_MASK, mb_chan->reg + REG_DB_STAT);
>>>> +               return 1;
>>>> +       }
>>>> +       return 0;
>>>> +}
>>>> +
>>>> +static irqreturn_t slimpro_mbox_irq(int irq, void *id)
>>>> +{
>>>> +       struct slimpro_mbox_chan *mb_chan = id;
>>>> +
>>>> +       if (mb_chan_status_ack(mb_chan))
>>>> +               mbox_chan_txdone(mb_chan->chan, 0);
>>>> +
>>>> +       if (mb_chan_status_avail(mb_chan))
>>>> +               mbox_chan_received_data(mb_chan->chan, mb_chan->rx_msg);
>>>> +
>>>> +       return IRQ_HANDLED;
>>>> +}
>>>> +
>>>> +static int slimpro_mbox_send_data(struct mbox_chan *chan, void *msg)
>>>> +{
>>>> +       struct slimpro_mbox_chan *mb_chan = chan->con_priv;
>>>> +
>>>> +       mb_chan_send_msg(mb_chan, msg);
>>>> +       return 0;
>>>> +}
>>>> +
>>>> +static int slimpro_mbox_startup(struct mbox_chan *chan)
>>>> +{
>>>> +       struct slimpro_mbox_chan *mb_chan = chan->con_priv;
>>>> +       int rc;
>>>> +       u32 val;
>>>> +
>>>> +       rc = devm_request_irq(mb_chan->dev, mb_chan->irq, slimpro_mbox_irq, 0,
>>>> +                             MBOX_CON_NAME, mb_chan);
>>>> +       if (unlikely(rc)) {
>>>> +               dev_err(mb_chan->dev, "failed to register mailbox interrupt %d\n",
>>>> +                       mb_chan->irq);
>>>> +               return rc;
>>>> +       }
>>>> +
>>>> +       /* Enable HW interrupt */
>>>> +       writel(MBOX_STATUS_ACK_MASK | MBOX_STATUS_AVAIL_MASK,
>>>> +              mb_chan->reg + REG_DB_STAT);
>>>> +       /* Unmask doorbell status interrupt */
>>>> +       val = readl(mb_chan->reg + REG_DB_STATMASK);
>>>> +       val &= ~(MBOX_STATUS_ACK_MASK | MBOX_STATUS_AVAIL_MASK);
>>>> +       writel(val, mb_chan->reg + REG_DB_STATMASK);
>>>> +
>>>> +       return 0;
>>>> +}
>>>> +
>>>> +static void slimpro_mbox_shutdown(struct mbox_chan *chan)
>>>> +{
>>>> +       struct slimpro_mbox_chan *mb_chan = chan->con_priv;
>>>> +       u32 val;
>>>> +
>>>> +       /* Mask doorbell status interrupt */
>>>> +       val = readl(mb_chan->reg + REG_DB_STATMASK);
>>>> +       val |= (MBOX_STATUS_ACK_MASK | MBOX_STATUS_AVAIL_MASK);
>>>> +       writel(val, mb_chan->reg + REG_DB_STATMASK);
>>>> +
>>>> +       devm_free_irq(mb_chan->dev, mb_chan->irq, mb_chan);
>>>> +}
>>>> +
>>>> +static struct mbox_chan_ops slimpro_mbox_ops = {
>>>> +       .send_data = slimpro_mbox_send_data,
>>>> +       .startup = slimpro_mbox_startup,
>>>> +       .shutdown = slimpro_mbox_shutdown,
>>>> +};
>>>> +
>>>> +static int slimpro_mbox_probe(struct platform_device *pdev)
>>>> +{
>>>> +       struct slimpro_mbox *ctx;
>>>> +       struct resource *regs;
>>>> +       void __iomem *mb_base;
>>>> +       int rc;
>>>> +       int i;
>>>> +
>>>> +       ctx = devm_kzalloc(&pdev->dev, sizeof(struct slimpro_mbox), GFP_KERNEL);
>>>> +       if (IS_ERR(ctx))
>>>> +               return PTR_ERR(ctx);
>>>> +
>>>> +       platform_set_drvdata(pdev, ctx);
>>>> +
>>>> +       regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>>> +       mb_base = devm_ioremap(&pdev->dev, regs->start, resource_size(regs));
>>>> +       if (IS_ERR(mb_base))
>>>> +               return PTR_ERR(mb_base);
>>>> +
>>>> +       /* Setup mailbox links */
>>>> +       for (i = 0; i < MBOX_CNT; i++) {
>>>> +               ctx->mc[i].irq = platform_get_irq(pdev, i);
>>>> +               if (ctx->mc[i].irq < 0) {
>>>> +                       if (i == 0) {
>>>> +                               dev_err(&pdev->dev, "no available IRQ\n");
>>>> +                               return -EINVAL;
>>>> +                       }
>>>> +                       dev_info(&pdev->dev, "no IRQ for channel %d\n", i);
>>>> +                       break;
>>>> +               }
>>>> +
>>>> +               ctx->mc[i].dev = &pdev->dev;
>>>> +               ctx->mc[i].reg = mb_base + i * MBOX_REG_SET_OFFSET;
>>>> +               ctx->mc[i].chan = &ctx->chans[i];
>>>> +               ctx->chans[i].con_priv = &ctx->mc[i];
>>>> +       }
>>>> +
>>>> +       /* Setup mailbox controller */
>>>> +       ctx->mb_ctrl.dev = &pdev->dev;
>>>> +       ctx->mb_ctrl.chans = ctx->chans;
>>>> +       ctx->mb_ctrl.txdone_irq = true;
>>>> +       ctx->mb_ctrl.ops = &slimpro_mbox_ops;
>>>> +       ctx->mb_ctrl.num_chans = i;
>>>> +
>>>> +       rc = mbox_controller_register(&ctx->mb_ctrl);
>>>> +       if (rc) {
>>>> +               dev_err(&pdev->dev,
>>>> +                       "APM X-Gene SLIMpro MailBox register failed:%d\n", rc);
>>>> +               return rc;
>>>> +       }
>>>> +
>>>> +       dev_info(&pdev->dev, "APM X-Gene SLIMpro MailBox registered\n");
>>>> +       return 0;
>>>> +}
>>>> +
>>>> +static int slimpro_mbox_remove(struct platform_device *pdev)
>>>> +{
>>>> +       struct slimpro_mbox *smb = platform_get_drvdata(pdev);
>>>> +
>>>> +       mbox_controller_unregister(&smb->mb_ctrl);
>>>> +       return 0;
>>>> +}
>>>> +
>>>> +static const struct of_device_id slimpro_of_match[] = {
>>>> +       {.compatible = "apm,xgene-slimpro-mbox" },
>>>> +       { },
>>>> +};
>>>> +MODULE_DEVICE_TABLE(of, slimpro_of_match);
>>>> +
>>>> +#ifdef CONFIG_ACPI
>>>> +static const struct acpi_device_id slimpro_acpi_ids[] = {
>>>> +       {"APMC0D01", 0},
>>>> +       {}
>>>> +};
>>>> +MODULE_DEVICE_TABLE(acpi, slimpro_acpi_ids);
>>>> +#endif
>>>> +
>>>> +static struct platform_driver slimpro_mbox_driver = {
>>>> +       .probe  = slimpro_mbox_probe,
>>>> +       .remove = slimpro_mbox_remove,
>>>> +       .driver = {
>>>> +               .name = "xgene-slimpro-mbox",
>>>> +               .of_match_table = of_match_ptr(slimpro_of_match),
>>>> +               .acpi_match_table = ACPI_PTR(slimpro_acpi_ids)
>>>> +       },
>>>> +};
>>>> +
>>>> +static int __init slimpro_mbox_init(void)
>>>> +{
>>>> +       return platform_driver_register(&slimpro_mbox_driver);
>>>> +}
>>>> +
>>>> +static void __exit slimpro_mbox_exit(void)
>>>> +{
>>>> +       platform_driver_unregister(&slimpro_mbox_driver);
>>>> +}
>>>> +
>>>> +subsys_initcall(slimpro_mbox_init);
>>>> +module_exit(slimpro_mbox_exit);
>>>> +
>>>> +MODULE_DESCRIPTION("APM X-Gene SLIMpro Mailbox Driver");
>>>> +MODULE_LICENSE("GPL");
>>>> --
>>>> 1.9.1
>>>>