Re: [PATCH v2 3/5] soc: add polarfire soc system controller

[Damien Le Moal <Damien.LeMoal@wdc.com>]

On 2020/12/01 21:18, Ben Dooks wrote:
> On 01/12/2020 12:00, Damien Le Moal wrote:
>> On 2020/12/01 20:03, conor.dooley@microchip.com wrote:
>>> From: Conor Dooley <conor.dooley@microchip.com>
>>>
>>> This driver provides an interface for other drivers to access the
>>> functions of the system controller on the Microchip PolarFire SoC.
>>>
>>> Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
>>> ---
>>>   drivers/soc/Kconfig                         |   1 +
>>>   drivers/soc/Makefile                        |   1 +
>>>   drivers/soc/microchip/Kconfig               |  10 ++
>>>   drivers/soc/microchip/Makefile              |   1 +
>>>   drivers/soc/microchip/mpfs_sys_controller.c | 135 ++++++++++++++++++++
>>>   5 files changed, 148 insertions(+)
>>>   create mode 100644 drivers/soc/microchip/Kconfig
>>>   create mode 100644 drivers/soc/microchip/Makefile
>>>   create mode 100644 drivers/soc/microchip/mpfs_sys_controller.c
>>>
>>> diff --git a/drivers/soc/Kconfig b/drivers/soc/Kconfig
>>> index 425ab6f7e375..22cb097bcbdc 100644
>>> --- a/drivers/soc/Kconfig
>>> +++ b/drivers/soc/Kconfig
>>> @@ -9,6 +9,7 @@ source "drivers/soc/bcm/Kconfig"
>>>   source "drivers/soc/fsl/Kconfig"
>>>   source "drivers/soc/imx/Kconfig"
>>>   source "drivers/soc/ixp4xx/Kconfig"
>>> +source "drivers/soc/microchip/Kconfig"
>>>   source "drivers/soc/mediatek/Kconfig"
>>>   source "drivers/soc/qcom/Kconfig"
>>>   source "drivers/soc/renesas/Kconfig"
>>> diff --git a/drivers/soc/Makefile b/drivers/soc/Makefile
>>> index 36452bed86ef..fb084cf2d12e 100644
>>> --- a/drivers/soc/Makefile
>>> +++ b/drivers/soc/Makefile
>>> @@ -14,6 +14,7 @@ obj-$(CONFIG_ARCH_GEMINI)	+= gemini/
>>>   obj-y				+= imx/
>>>   obj-$(CONFIG_ARCH_IXP4XX)	+= ixp4xx/
>>>   obj-$(CONFIG_SOC_XWAY)		+= lantiq/
>>> +obj-$(CONFIG_SOC_MICROCHIP_POLARFIRE)	+= microchip/
>>>   obj-y				+= mediatek/
>>>   obj-y				+= amlogic/
>>>   obj-y				+= qcom/
>>> diff --git a/drivers/soc/microchip/Kconfig b/drivers/soc/microchip/Kconfig
>>> new file mode 100644
>>> index 000000000000..40e5203c8ba0
>>> --- /dev/null
>>> +++ b/drivers/soc/microchip/Kconfig
>>> @@ -0,0 +1,10 @@
>>> +config MPFS_SYS_CONTROLLER
>>> +	tristate "MPFS_SYS_CONTROLLER"
>>> +	depends on MPFS_MBOX
>>> +	help
>>> +	  This driver adds support for the Polarfire SoC system controller.
>>> +
>>> +	  To compile this driver as a module, choose M here. the
>>> +	  module will be called mpfs_system_controller.
>>> +
>>> +	  If unsure, say N.
>>> diff --git a/drivers/soc/microchip/Makefile b/drivers/soc/microchip/Makefile
>>> new file mode 100644
>>> index 000000000000..23b1f42a37db
>>> --- /dev/null
>>> +++ b/drivers/soc/microchip/Makefile
>>> @@ -0,0 +1 @@
>>> +obj-$(CONFIG_MPFS_SYS_CONTROLLER)	+= mpfs_sys_controller.o
>>> diff --git a/drivers/soc/microchip/mpfs_sys_controller.c b/drivers/soc/microchip/mpfs_sys_controller.c
>>> new file mode 100644
>>> index 000000000000..875a0671e196
>>> --- /dev/null
>>> +++ b/drivers/soc/microchip/mpfs_sys_controller.c
>>> @@ -0,0 +1,135 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +/*
>>> + * Microchip MPFS system controller driver
>>> + *
>>> + * Copyright (c) 2020 Microchip Corporation. All rights reserved.
>>> + *
>>> + * Author: Conor Dooley <conor.dooley@microchip.com>
>>> + *
>>> + */
>>> +
>>> +#include <linux/slab.h>
>>> +#include <linux/module.h>
>>> +#include <linux/interrupt.h>
>>> +#include <linux/of_platform.h>
>>> +#include <linux/mailbox_client.h>
>>> +#include <linux/platform_device.h>
>>> +#include <soc/microchip/mpfs.h>
>>> +
>>> +static DEFINE_MUTEX(transaction_lock);
>>> +
>>> +struct mpfs_sys_controller {
>>> +	struct mbox_client client;
>>> +	struct mbox_chan *chan;
>>> +	struct completion c;
>>> +	u32 enabled;
>>> +	void *response;
>>> +	u16 response_size_bytes;
>>> +};
>>> +
>>> +int mpfs_blocking_transaction(struct mpfs_sys_controller *mpfs_client, void *msg,
>>> +			      void *response, u16 response_size_bytes)
>>> +{
>>> +	int ret;
>>> +
>>> +	mpfs_client->response = response;
>>> +	mpfs_client->response_size_bytes = response_size_bytes;
>>> +
>>> +	mutex_lock_interruptible(&transaction_lock);
>>> +
>>> +	reinit_completion(&mpfs_client->c);
>>> +
>>> +	ret = mbox_send_message(mpfs_client->chan, msg);
>>> +	if (ret >= 0) {
>>> +		if (wait_for_completion_timeout(&mpfs_client->c, HZ)) {
>>> +			ret = 0;
>>> +		} else {
>>> +			ret = -ETIMEDOUT;
>>> +			dev_warn(mpfs_client->client.dev, "MPFS sys controller transaction timeout");
>>> +		}
>>> +	} else {
>>> +		dev_err(mpfs_client->client.dev,
>>> +			"mpfs sys controller transaction returned %d\r\n", ret);
>>> +	}
>>> +
>>> +	mutex_unlock(&transaction_lock);
>>> +
>>> +	return ret;
>>> +}
>>> +EXPORT_SYMBOL(mpfs_blocking_transaction);
>>> +
>>> +static void rx_callback(struct mbox_client *client, void *msg)
>>> +{
>>> +	struct mpfs_sys_controller *mpfs_client =
>>> +		container_of(client, struct mpfs_sys_controller, client);
>>> +
>>> +	memcpy(mpfs_client->response, (u8 *)msg,
>>> +	       mpfs_client->response_size_bytes);
>>> +
>>> +	complete(&mpfs_client->c);
>>> +}
>>> +
>>> +static int mpfs_sys_controller_probe(struct platform_device *pdev)
>>> +{
>>> +	struct device *dev = &pdev->dev;
>>> +	struct mpfs_sys_controller *mpfs_client;
>>> +
>>> +	mpfs_client = devm_kzalloc(dev, sizeof(*mpfs_client), GFP_KERNEL);
>>> +	if (!mpfs_client)
>>> +		return -ENOMEM;
>>> +
>>> +	mpfs_client->client.dev = dev;
>>> +	mpfs_client->client.rx_callback = rx_callback;
>>> +	mpfs_client->client.tx_block = 1U;
>>> +
>>> +	mpfs_client->chan = mbox_request_channel_byname(&mpfs_client->client,
>>> +							"mbox-mpfs");
>>> +	if (IS_ERR(mpfs_client->chan)) {
>>> +		int ret = PTR_ERR(mpfs_client->chan);
>>> +
>>> +		if (ret != -EPROBE_DEFER)
>>> +			dev_err(dev, "Failed to get mbox channel: %d\n", ret);
>>> +		return ret;
>>
>> You can replace all of this with
>>
>> 		return dev_err_probe(dev, PTR_ERR(mpfs_client->chan),
>> 				     ""Failed to get mbox channel\n");
> 
> you'll spam the error log if you get a lot of probe defferals.
> I think the code as is fine.

Please look at that function code: it does not print anything if the error is
-EPROBE_DEFER.

-- 
Damien Le Moal
Western Digital Research

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