linux-kernel - Re: [PATCH v3 2/4] drivers: firmware: xilinx: Add ZynqMP firmware driver

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Message-ID: <20180131182012.oshjmvahetaizlbu@lakrids.cambridge.arm.com>
Date:   Wed, 31 Jan 2018 18:20:12 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     Jolly Shah <jolly.shah@...inx.com>
Cc:     ard.biesheuvel@...aro.org, mingo@...nel.org,
        gregkh@...uxfoundation.org, matt@...eblueprint.co.uk,
        sudeep.holla@....com, hkallweit1@...il.com, keescook@...omium.org,
        dmitry.torokhov@...il.com, michal.simek@...inx.com,
        robh+dt@...nel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        Jolly Shah <jollys@...inx.com>, Rajan Vaja <rajanv@...inx.com>
Subject: Re: [PATCH v3 2/4] drivers: firmware: xilinx: Add ZynqMP firmware
 driver

On Wed, Jan 24, 2018 at 03:21:12PM -0800, Jolly Shah wrote:
> This patch is adding communication layer with firmware.
> Firmware driver provides an interface to firmware APIs.
> Interface APIs can be used by any driver to communicate to
> PMUFW(Platform Management Unit). All requests go through ATF.

> +/**
> + * zynqmp_pm_set_wakeup_source - PM call to specify the wakeup source
> + *					while suspended
> + * @target:	Node ID of the targeted PU or subsystem
> + * @wakeup_node:Node ID of the wakeup peripheral
> + * @enable:	Enable or disable the specified peripheral as wake source
> + *
> + * Return:	Returns status, either success or error+reason
> + */
> +static int zynqmp_pm_set_wakeup_source(const u32 target,
> +				       const u32 wakeup_node,
> +				       const u32 enable)
> +{
> +	return invoke_pm_fn(PM_SET_WAKEUP_SOURCE, target,
> +			    wakeup_node, enable, 0, NULL);
> +}

I see many functions take a "Node ID" parameter, but these don't appear
to be in any DT binding, and drivers (other than the debugfs driver)
aren't using them.

What's the plan for making use of these? Where are the node IDs going to
come from in practice?

> +/**
> + * zynqmp_pm_system_shutdown - PM call to request a system shutdown or restart
> + * @type:	Shutdown or restart? 0 for shutdown, 1 for restart
> + * @subtype:	Specifies which system should be restarted or shut down
> + *
> + * Return:	Returns status, either success or error+reason
> + */
> +static int zynqmp_pm_system_shutdown(const u32 type, const u32 subtype)
> +{
> +	return invoke_pm_fn(PM_SYSTEM_SHUTDOWN, type, subtype, 0, 0, NULL);
> +}

PSCI already has this functionality, so I'm a little confused by the
duplication.

[...]

> +/**
> + * zynqmp_pm_get_node_status - PM call to request a node's current power state
> + * @node:		ID of the component or sub-system in question
> + * @status:		Current operating state of the requested node
> + * @requirements:	Current requirements asserted on the node,
> + *			used for slave nodes only.
> + * @usage:		Usage information, used for slave nodes only:
> + *			0 - No master is currently using the node
> + *			1 - Only requesting master is currently using the node
> + *			2 - Only other masters are currently using the node
> + *			3 - Both the current and at least one other master
> + *			is currently using the node

These should probably have corresponding macros or enum values.

[...]

> +/**
> + * zynqmp_pm_sha_hash - Access the SHA engine to calculate the hash
> + * @address:	Address of the data/ Address of output buffer where
> + *		hash should be stored.
> + * @size:	Size of the data.
> + * @flags:
> + *	BIT(0) - Sha3 init (Here address and size inputs can be NULL)
> + *	BIT(1) - Sha3 update (address should holds the )

Missing "data", I guess?

> + *	BIT(2) - Sha3 final (address should hold the address of
> + *		 buffer to store hash)

Is the SHA engine coherent? Or is cache maintenance necessary?

[...]

> +/**
> + * zynqmp_pm_pinctrl_request - Request Pin from firmware
> + * @pin:	Pin number to request
> + *

No DT binding for the pinctrl bits?

[...]

> +/**
> + * zynqmp_pm_clock_enable - Enable the clock for given id
> + * @clock_id:	ID of the clock to be enabled
> + *

Likewise for the clocks?

> +/**
> + * get_eemi_ops	- Get eemi ops functions
> + *
> + * Return:	- pointer of eemi_ops structure
> + */
> +const struct zynqmp_eemi_ops *get_eemi_ops(void)
> +{
> +	return &eemi_ops;
> +}
> +EXPORT_SYMBOL_GPL(get_eemi_ops);
> +
> +static int __init zynqmp_plat_init(void)
> +{
> +	struct device_node *np;
> +	int ret = 0;
> +
> +	np = of_find_compatible_node(NULL, NULL, "xlnx,zynqmp");
> +	if (!np)
> +		return 0;
> +	of_node_put(np);
> +
> +	/* We're running on a ZynqMP machine, the PM node is mandatory. */
> +	np = of_find_compatible_node(NULL, NULL, "xlnx,zynqmp-firmware");
> +	if (!np) {
> +		pr_warn("%s: pm node not found\n", __func__);
> +		return -ENXIO;
> +	}
> +
> +	ret = get_set_conduit_method(np);
> +	if (ret) {
> +		of_node_put(np);
> +		return ret;
> +	}
> +
> +	/* Check PM API version number */
> +	zynqmp_pm_get_api_version(&pm_api_version);
> +	if (pm_api_version != ZYNQMP_PM_VERSION) {
> +		panic("%s power management API version error. Expected: v%d.%d - Found: v%d.%d\n",
> +		      __func__,
> +		      ZYNQMP_PM_VERSION_MAJOR, ZYNQMP_PM_VERSION_MINOR,
> +		      pm_api_version >> 16, pm_api_version & 0xffff);
> +	}
> +
> +	pr_info("%s Power management API v%d.%d\n", __func__,
> +		ZYNQMP_PM_VERSION_MAJOR, ZYNQMP_PM_VERSION_MINOR);
> +
> +	of_node_put(np);
> +
> +	return ret;
> +}
> +
> +early_initcall(zynqmp_plat_init);

Why does this need to be an early initcall? Can't we probe this as a
platform device?

Thanks,
Mark.