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

Duc Dang
2016-02-10T03:46:57Z

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.

>
>> +
>> +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
>>