[v3,2/2] mailbox: Add Broadcom STB mailbox driver
diff mbox series

Message ID 20200919192235.43872-3-james.quinlan@broadcom.com
State New, archived
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Series
  • mailbox: Add Broadcom STB mailbox driver
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Commit Message

Jim Quinlan Sept. 19, 2020, 7:22 p.m. UTC
This is a simple mailbox driver to be used by the SCMI protocol stack.  It
only implements the agent-to-platform channel; we may implement the
platform-to-agent channel in the future.  An unusual aspect of this driver
is how the completion of an SCMI message is indicated.  An SCMI message is
initiated with an ARM SMC call, but the return of this call does not
indicate the execution or completion of the message.  Rather, the message's
completion is signaled by an interrupt.

Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 drivers/mailbox/Kconfig           |  12 +++
 drivers/mailbox/Makefile          |   2 +
 drivers/mailbox/brcmstb-mailbox.c | 173 ++++++++++++++++++++++++++++++
 3 files changed, 187 insertions(+)
 create mode 100644 drivers/mailbox/brcmstb-mailbox.c

Comments

Randy Dunlap Sept. 19, 2020, 7:31 p.m. UTC | #1
Hi Jim,

On 9/19/20 12:22 PM, Jim Quinlan wrote:
> ---
>  drivers/mailbox/Kconfig           |  12 +++
>  drivers/mailbox/Makefile          |   2 +
>  drivers/mailbox/brcmstb-mailbox.c | 173 ++++++++++++++++++++++++++++++
>  3 files changed, 187 insertions(+)
>  create mode 100644 drivers/mailbox/brcmstb-mailbox.c
> 
> diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
> index 05b1009e2820..96faf1139cb9 100644
> --- a/drivers/mailbox/Kconfig
> +++ b/drivers/mailbox/Kconfig
> @@ -254,4 +254,16 @@ config QCOM_IPCC
>  	  acts as an interrupt controller for receiving interrupts from clients.
>  	  Say Y here if you want to build this driver.
>  
> +config BRCMSTB_MBOX
> +	tristate "Broadcom STB Mailbox"
> +	depends on ARM64 || ARM
> +	depends on ARM_SCMI_PROTOCOL && ARCH_BRCMSTB
> +	default ARM_SCMI_PROTOCOL && ARCH_BRCMSTB
> +        help

"help" is still indented with spaces instead of one tab.
You probably should wait a bit to see if there are other comments on this patch
before doing a v4.

> +	  Mailbox implementation of the Broadcom STB for the sole purposes
> +	  of SCMI communication.  This is used by the SCMI drivers to
> +	  communicate with FW that runs in EL3.  This mailbox only implements
> +	  the agent-to-platform channgel of SCMI but may be augmented in
> +	  the future to add the platform-to-agent channel.
> +
>  endif
> diff --git a/drivers/mailbox/brcmstb-mailbox.c b/drivers/mailbox/brcmstb-mailbox.c
> new file mode 100644
> index 000000000000..27d87938b08c
> --- /dev/null
> +++ b/drivers/mailbox/brcmstb-mailbox.c
> @@ -0,0 +1,173 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2017, Broadcom */

2017 is a little surprising.


> +#if defined(CONFIG_ARM64) || defined(CONFIG_ARM)
> +static int announce_msg(unsigned int mbox_num, unsigned int ch)
> +{
> +	struct arm_smccc_res res;
> +
> +	if (ch >= NUM_CHAN)
> +		return -EIO;
> +	arm_smccc_smc(BRCM_FID(ch), mbox_num, 0, 0, 0, 0, 0, 0, &res);
> +	if (res.a0)
> +		return -EIO;
> +	return 0;
> +}
> +#else
> +#error Func announce_msg() not defined for the current ARCH
> +#endif

This is handled by the Kconfig depends on clause.
Why is it repeated here?



thanks.
Jim Quinlan Sept. 19, 2020, 9:04 p.m. UTC | #2
On Sat, Sep 19, 2020 at 3:32 PM Randy Dunlap <rdunlap@infradead.org> wrote:
>
> Hi Jim,
>
> On 9/19/20 12:22 PM, Jim Quinlan wrote:
> > ---
> >  drivers/mailbox/Kconfig           |  12 +++
> >  drivers/mailbox/Makefile          |   2 +
> >  drivers/mailbox/brcmstb-mailbox.c | 173 ++++++++++++++++++++++++++++++
> >  3 files changed, 187 insertions(+)
> >  create mode 100644 drivers/mailbox/brcmstb-mailbox.c
> >
> > diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
> > index 05b1009e2820..96faf1139cb9 100644
> > --- a/drivers/mailbox/Kconfig
> > +++ b/drivers/mailbox/Kconfig
> > @@ -254,4 +254,16 @@ config QCOM_IPCC
> >         acts as an interrupt controller for receiving interrupts from clients.
> >         Say Y here if you want to build this driver.
> >
> > +config BRCMSTB_MBOX
> > +     tristate "Broadcom STB Mailbox"
> > +     depends on ARM64 || ARM
> > +     depends on ARM_SCMI_PROTOCOL && ARCH_BRCMSTB
> > +     default ARM_SCMI_PROTOCOL && ARCH_BRCMSTB
> > +        help
>
> "help" is still indented with spaces instead of one tab.
> You probably should wait a bit to see if there are other comments on this patch
> before doing a v4.
Hi Randy,

Will fix, then wait...
>
> > +       Mailbox implementation of the Broadcom STB for the sole purposes
> > +       of SCMI communication.  This is used by the SCMI drivers to
> > +       communicate with FW that runs in EL3.  This mailbox only implements
> > +       the agent-to-platform channgel of SCMI but may be augmented in
> > +       the future to add the platform-to-agent channel.
> > +
> >  endif
> > diff --git a/drivers/mailbox/brcmstb-mailbox.c b/drivers/mailbox/brcmstb-mailbox.c
> > new file mode 100644
> > index 000000000000..27d87938b08c
> > --- /dev/null
> > +++ b/drivers/mailbox/brcmstb-mailbox.c
> > @@ -0,0 +1,173 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (c) 2017, Broadcom */
>
> 2017 is a little surprising.
Will fix.

>
>
> > +#if defined(CONFIG_ARM64) || defined(CONFIG_ARM)
> > +static int announce_msg(unsigned int mbox_num, unsigned int ch)
> > +{
> > +     struct arm_smccc_res res;
> > +
> > +     if (ch >= NUM_CHAN)
> > +             return -EIO;
> > +     arm_smccc_smc(BRCM_FID(ch), mbox_num, 0, 0, 0, 0, 0, 0, &res);
> > +     if (res.a0)
> > +             return -EIO;
> > +     return 0;
> > +}
> > +#else
> > +#error Func announce_msg() not defined for the current ARCH
> > +#endif
>
> This is handled by the Kconfig depends on clause.
> Why is it repeated here?
Will fix.

Thanks,
Jim
>
>
>
> thanks.
> --
> ~Randy
>
Sudeep Holla Oct. 9, 2020, 4:38 p.m. UTC | #3
On Sat, Sep 19, 2020 at 03:22:30PM -0400, Jim Quinlan wrote:
> only implements the agent-to-platform channel;

In that case any reason why you can't reuse the existing smc transport
for SCMI. It was added recently in case you haven't checked the latest
kernel version(v5.8 or above). Check out for drivers/firmware/arm_scmi/smc.c
IIUC rather vaguely Florian was cc-ed on those patches.

> we may implement the platform-to-agent channel in the future.

This is not yet support with that transport, it is hard to generalise
as different vendors have their own solutions there.

> An unusual aspect of this driver is how the completion of an SCMI message
> is indicated.  An SCMI message is initiated with an ARM SMC call, but the
> return of this call does not indicate the execution or completion of the
> message.  Rather, the message's completion is signaled by an interrupt.
>

So are these not fast SMC/HVC calls then ? If so we may need some changes
to that driver. I just rejected multiple message support as we had assumed
fast smc/hvc.
Florian Fainelli Oct. 9, 2020, 5:03 p.m. UTC | #4
On 10/9/2020 9:38 AM, Sudeep Holla wrote:
> On Sat, Sep 19, 2020 at 03:22:30PM -0400, Jim Quinlan wrote:
>> only implements the agent-to-platform channel;
> 
> In that case any reason why you can't reuse the existing smc transport
> for SCMI. It was added recently in case you haven't checked the latest
> kernel version(v5.8 or above). Check out for drivers/firmware/arm_scmi/smc.c
> IIUC rather vaguely Florian was cc-ed on those patches.

Our firmware completes all commands by posting an interrupt and we 
already have platforms in the field with this mailbox driver. I was 
hoping we could make use of the SMC transport, but the current firmware 
implementation completes commands by raising an interrupt. The reason 
why we did that was that we could support synchronous and asynchronous 
calls the same way.

> 
>> we may implement the platform-to-agent channel in the future.
> 
> This is not yet support with that transport, it is hard to generalise
> as different vendors have their own solutions there.
> 
>> An unusual aspect of this driver is how the completion of an SCMI message
>> is indicated.  An SCMI message is initiated with an ARM SMC call, but the
>> return of this call does not indicate the execution or completion of the
>> message.  Rather, the message's completion is signaled by an interrupt.
>>
> 
> So are these not fast SMC/HVC calls then ? If so we may need some changes
> to that driver. I just rejected multiple message support as we had assumed
> fast smc/hvc.
>
Jim Quinlan Oct. 21, 2020, 9:38 p.m. UTC | #5
On Fri, Oct 9, 2020 at 12:38 PM Sudeep Holla <sudeep.holla@arm.com> wrote:
>
> On Sat, Sep 19, 2020 at 03:22:30PM -0400, Jim Quinlan wrote:
> > only implements the agent-to-platform channel;
>
> In that case any reason why you can't reuse the existing smc transport
> for SCMI. It was added recently in case you haven't checked the latest
> kernel version(v5.8 or above). Check out for drivers/firmware/arm_scmi/smc.c
> IIUC rather vaguely Florian was cc-ed on those patches.

Hi Sudeep,

Sorry for the delay.  As Florian mentioned, we tried to use what
you've submitted but could not because in our system a return does not
indicate the completion of the SCMI operation.  It is indicated by an
interrupt.  There are a number of reasons for this and some are out of
our control.
>
>
> > we may implement the platform-to-agent channel in the future.
>
> This is not yet support with that transport, it is hard to generalise
> as different vendors have their own solutions there.
>
> > An unusual aspect of this driver is how the completion of an SCMI message
> > is indicated.  An SCMI message is initiated with an ARM SMC call, but the
> > return of this call does not indicate the execution or completion of the
> > message.  Rather, the message's completion is signaled by an interrupt.
> >
>
> So are these not fast SMC/HVC calls then ? If so we may need some changes
> to that driver. I just rejected multiple message support as we had assumed
> fast smc/hvc.

Yes, we are using fast SMC calls.  We don't have multiple message
support either.  The disconnect we have with the smc/hvc transport
commit si this:

smc_send_message(...)
{
/* ... */
+ arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res);
+ scmi_rx_callback(scmi_info->cinfo, shmem_read_header(scmi_info->shmem));

In our code the second line is not here but in the interrupt handler.
I don't see any way you can easily change/augment the smc/hvc
transport to accommodate us.

Regards,
Jim





>
>
> --
> Regards,
> Sudeep

Patch
diff mbox series

diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index 05b1009e2820..96faf1139cb9 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -254,4 +254,16 @@  config QCOM_IPCC
 	  acts as an interrupt controller for receiving interrupts from clients.
 	  Say Y here if you want to build this driver.
 
+config BRCMSTB_MBOX
+	tristate "Broadcom STB Mailbox"
+	depends on ARM64 || ARM
+	depends on ARM_SCMI_PROTOCOL && ARCH_BRCMSTB
+	default ARM_SCMI_PROTOCOL && ARCH_BRCMSTB
+        help
+	  Mailbox implementation of the Broadcom STB for the sole purposes
+	  of SCMI communication.  This is used by the SCMI drivers to
+	  communicate with FW that runs in EL3.  This mailbox only implements
+	  the agent-to-platform channgel of SCMI but may be augmented in
+	  the future to add the platform-to-agent channel.
+
 endif
diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
index 60d224b723a1..a74efd02eece 100644
--- a/drivers/mailbox/Makefile
+++ b/drivers/mailbox/Makefile
@@ -54,3 +54,5 @@  obj-$(CONFIG_SUN6I_MSGBOX)	+= sun6i-msgbox.o
 obj-$(CONFIG_SPRD_MBOX)		+= sprd-mailbox.o
 
 obj-$(CONFIG_QCOM_IPCC)		+= qcom-ipcc.o
+
+obj-$(CONFIG_BRCMSTB_MBOX)	+= brcmstb-mailbox.o
diff --git a/drivers/mailbox/brcmstb-mailbox.c b/drivers/mailbox/brcmstb-mailbox.c
new file mode 100644
index 000000000000..27d87938b08c
--- /dev/null
+++ b/drivers/mailbox/brcmstb-mailbox.c
@@ -0,0 +1,173 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2017, Broadcom */
+
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/mailbox_controller.h>
+#include <linux/mailbox_client.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#if defined(CONFIG_ARM64) || defined(CONFIG_ARM)
+#include <linux/arm-smccc.h>
+#endif
+
+#define BRCM_SCMI_SMC_OEM_FUNC	0x400
+#define BRCM_SCMI_MBOX_NUM	0
+#define BRCM_FID(ch) ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
+			IS_ENABLED(CONFIG_ARM64), \
+			ARM_SMCCC_OWNER_OEM, \
+			BRCM_SCMI_SMC_OEM_FUNC + (ch))
+enum {
+	A2P_CHAN = 0,
+	NUM_CHAN
+};
+
+struct chan_priv {
+	unsigned int mbox_num;
+	unsigned int ch;
+};
+
+struct brcm_mbox {
+	struct mbox_controller controller;
+	int irqs[NUM_CHAN];
+};
+
+static struct mbox_chan *brcm_mbox_of_xlate(struct mbox_controller *controller,
+					    const struct of_phandle_args *sp)
+{
+	unsigned int ch = sp->args[0];
+	struct brcm_mbox *mbox
+		= container_of(controller, struct brcm_mbox, controller);
+
+	if (!mbox || ch >= NUM_CHAN)
+		return ERR_PTR(-ENOENT);
+
+	return &mbox->controller.chans[ch];
+}
+
+#if defined(CONFIG_ARM64) || defined(CONFIG_ARM)
+static int announce_msg(unsigned int mbox_num, unsigned int ch)
+{
+	struct arm_smccc_res res;
+
+	if (ch >= NUM_CHAN)
+		return -EIO;
+	arm_smccc_smc(BRCM_FID(ch), mbox_num, 0, 0, 0, 0, 0, 0, &res);
+	if (res.a0)
+		return -EIO;
+	return 0;
+}
+#else
+#error Func announce_msg() not defined for the current ARCH
+#endif
+
+static int brcm_mbox_send_data(struct mbox_chan *chan, void *data)
+{
+	struct chan_priv *priv = chan->con_priv;
+
+	return announce_msg(priv->mbox_num, priv->ch);
+}
+
+static int brcm_mbox_startup(struct mbox_chan *chan)
+{
+	return 0;
+}
+
+static const struct mbox_chan_ops brcm_mbox_ops = {
+	.send_data = brcm_mbox_send_data,
+	.startup = brcm_mbox_startup,
+};
+
+static irqreturn_t brcm_a2p_isr(int irq, void *data)
+{
+	struct mbox_chan *chan = data;
+
+	mbox_chan_received_data(chan, NULL);
+	return IRQ_HANDLED;
+}
+
+static int brcm_mbox_probe(struct platform_device *pdev)
+{
+	struct brcm_mbox *mbox;
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct chan_priv *chan_priv;
+	int ret;
+
+	if (!np)
+		return -EINVAL;
+
+	mbox = devm_kzalloc(&pdev->dev, sizeof(*mbox), GFP_KERNEL);
+	if (!mbox)
+		return -ENOMEM;
+
+	/* Allocate channels */
+	mbox->controller.chans = devm_kzalloc(
+		&pdev->dev, NUM_CHAN * sizeof(struct mbox_chan), GFP_KERNEL);
+	if (!mbox->controller.chans)
+		return -ENOMEM;
+	chan_priv = devm_kzalloc(
+		&pdev->dev, NUM_CHAN * sizeof(struct chan_priv), GFP_KERNEL);
+	if (!chan_priv)
+		return -ENOMEM;
+
+	mbox->irqs[A2P_CHAN] = platform_get_irq(pdev, 0);
+	ret = devm_request_irq(&pdev->dev, mbox->irqs[A2P_CHAN], brcm_a2p_isr,
+				IRQF_NO_SUSPEND, "brcm: SCMI a2p intr",
+				&mbox->controller.chans[A2P_CHAN]);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to setup SCMI a2p isr\n");
+		return ret;
+	}
+	chan_priv[A2P_CHAN].mbox_num = BRCM_SCMI_MBOX_NUM;
+	chan_priv[A2P_CHAN].ch = A2P_CHAN;
+	mbox->controller.chans[A2P_CHAN].con_priv = &chan_priv[A2P_CHAN];
+	mbox->controller.num_chans++;
+	mbox->controller.dev = &pdev->dev;
+	mbox->controller.ops = &brcm_mbox_ops;
+	mbox->controller.of_xlate = brcm_mbox_of_xlate;
+	ret = mbox_controller_register(&mbox->controller);
+	if (ret) {
+		dev_err(dev, "failed to register BrcmSTB mbox\n");
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, mbox);
+	return 0;
+}
+
+static int brcm_mbox_remove(struct platform_device *pdev)
+{
+	struct brcm_mbox *mbox = platform_get_drvdata(pdev);
+
+	mbox_controller_unregister(&mbox->controller);
+
+	return 0;
+}
+
+static const struct of_device_id brcm_mbox_of_match[] = {
+	{ .compatible = "brcm,brcmstb-mbox", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, brcm_mbox_of_match);
+
+static struct platform_driver brcm_mbox_driver = {
+	.probe = brcm_mbox_probe,
+	.remove = brcm_mbox_remove,
+	.driver = {
+		.name = "brcm_mbox",
+		.of_match_table = brcm_mbox_of_match,
+	},
+};
+
+module_platform_driver(brcm_mbox_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Broadcom STB SCMI Mailbox driver");
+MODULE_AUTHOR("Broadcom");