[PATCH 02/11] misc: Versatile Express config bus infrastructure

[arnd@arndb.de (Arnd Bergmann)]

On Monday 03 September 2012, Pawel Moll wrote:
> +	dcc at 0 {
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +		#interrupt-cells = <0>;
> +		arm,vexpress,site = <0xff>; /* Master site */
> +
> +		osc at 0 {
> +			compatible = "arm,vexpress-config,osc";
> +			reg = <0>;
> +			freq-range = <50000000 100000000>;
> +			#clock-cells = <1>;
> +			clock-output-names = "oscclk0";
> +		};
> +	};
>  };

The #interrupt-cells property seems misplaced here.

> --- a/drivers/misc/Kconfig
> +++ b/drivers/misc/Kconfig
> @@ -517,4 +517,5 @@ source "drivers/misc/lis3lv02d/Kconfig"
>  source "drivers/misc/carma/Kconfig"
>  source "drivers/misc/altera-stapl/Kconfig"
>  source "drivers/misc/mei/Kconfig"
> +source "drivers/misc/vexpress/Kconfig"
>  endmenu
> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
> index b88df7a..49964fd 100644
> --- a/drivers/misc/Makefile
> +++ b/drivers/misc/Makefile
> @@ -50,3 +50,4 @@ obj-y				+= carma/
>  obj-$(CONFIG_USB_SWITCH_FSA9480) += fsa9480.o
>  obj-$(CONFIG_ALTERA_STAPL)	+=altera-stapl/
>  obj-$(CONFIG_INTEL_MEI)		+= mei/
> +obj-y				+= vexpress/

This does not look like something that should go to drivers/misc (well,
basically nothing ever does). How about drivers/mfd or drivers/bus instead?

> +#define ADDR_FMT "%u.%x:%x:%x:%x"
> +
> +#define ADDR_ARGS(_ptr) \
> +		_ptr->func, _ptr->addr.site, _ptr->addr.position, \
> +		_ptr->addr.dcc, _ptr->addr.device

Can't you use dev_printk() to print the device name in the normal format?

> +#define ADDR_TO_U64(addr) \
> +		(((u64)(addr).site << 32) | ((addr).position << 24) | \
> +		((addr).dcc << 16) | (addr).device)
> +
> +static bool vexpress_config_early = true;
> +static DEFINE_MUTEX(vexpress_config_early_mutex);
> +static LIST_HEAD(vexpress_config_early_drivers);
> +static LIST_HEAD(vexpress_config_early_devices);

What is the reason for needing early devices that you have to keep in a list
like this? If it's only for setup purposes, it's probably easier to
have a platform hook that probes the hardware you want to initialize at boot
time and only start using the device method at device init time.

> +static int vexpress_config_match(struct device *dev, struct device_driver *drv)
> +{
> +	struct vexpress_config_device *vecdev = to_vexpress_config_device(dev);
> +	struct vexpress_config_driver *vecdrv = to_vexpress_config_driver(drv);
> +
> +	if (vecdrv->funcs) {
> +		const unsigned *func = vecdrv->funcs;
> +
> +		while (*func) {
> +			if (*func == vecdev->func)
> +				return 1;
> +			func++;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static struct device vexpress_config_bus = {
> +	.init_name = "vexpress-config",
> +};

No static devices in new code please. Just put it into the device tree.


> +struct bus_type vexpress_config_bus_type = {
> +	.name = "vexpress-config",
> +	.match = vexpress_config_match,
> +};

What is the reason for having a separate bus_type here?
Is this a discoverable bus? If it is, why do you need a
device tree binding for the child devices?


> +#define VEXPRESS_COMPATIBLE_TO_FUNC(_compatible, _func) \
> +	{ \
> +		.compatible = "arm,vexpress-config," _compatible, \
> +		.data = (void *)VEXPRESS_CONFIG_FUNC_##_func \
> +	}
> +
> +static struct of_device_id vexpress_config_devices_matches[] = {
> +	VEXPRESS_COMPATIBLE_TO_FUNC("osc", OSC),
> +	VEXPRESS_COMPATIBLE_TO_FUNC("volt", VOLT),
> +	VEXPRESS_COMPATIBLE_TO_FUNC("amp", AMP),
> +	VEXPRESS_COMPATIBLE_TO_FUNC("temp", TEMP),
> +	VEXPRESS_COMPATIBLE_TO_FUNC("reset", RESET),
> +	VEXPRESS_COMPATIBLE_TO_FUNC("scc", SCC),
> +	VEXPRESS_COMPATIBLE_TO_FUNC("muxfpga", MUXFPGA),
> +	VEXPRESS_COMPATIBLE_TO_FUNC("shutdown", SHUTDOWN),
> +	VEXPRESS_COMPATIBLE_TO_FUNC("reboot", REBOOT),
> +	VEXPRESS_COMPATIBLE_TO_FUNC("dvimode", DVIMODE),
> +	VEXPRESS_COMPATIBLE_TO_FUNC("power", POWER),
> +	VEXPRESS_COMPATIBLE_TO_FUNC("energy", ENERGY),
> +	{},
> +};

What is the purpose of this lookup? Can't you make the child devices get
probed by the compatible value?

> +static void vexpress_config_of_device_add(struct device_node *node)
> +{
> +	int err;
> +	struct vexpress_config_device *vecdev;
> +	const struct of_device_id *match;
> +	u32 value;
> +
> +	if (!of_device_is_available(node))
> +		return;
> +
> +	vecdev = kzalloc(sizeof(*vecdev), GFP_KERNEL);
> +	if (WARN_ON(!vecdev))
> +		return;
> +
> +	vecdev->dev.of_node = of_node_get(node);
> +
> +	vecdev->name = node->name;
> +
> +	match = of_match_node(vexpress_config_devices_matches, node);
> +	vecdev->func = (unsigned)match->data;
> +
> +	err = of_property_read_u32(node->parent, "arm,vexpress,site", &value);
> +	if (!err)
> +		vecdev->addr.site = value;
> +
> +	err = of_property_read_u32(node->parent, "arm,vexpress,position",
> +			&value);
> +	if (!err)
> +		vecdev->addr.position = value;
> +
> +	err = of_property_read_u32(node->parent, "arm,vexpress,dcc", &value);
> +	if (!err)
> +		vecdev->addr.dcc = value;
> +
> +	err = of_property_read_u32(node, "reg", &value);
> +	if (!err) {
> +		vecdev->addr.device = value;
> +	} else {
> +		pr_err("Invalid reg property in '%s'! (%d)\n",
> +				node->full_name, err);
> +		kfree(vecdev);
> +		return;
> +	}
> +
> +	err = vexpress_config_device_register(vecdev);
> +	if (err) {
> +		pr_err("Failed to add OF device '%s'! (%d)\n",
> +				node->full_name, err);
> +		kfree(vecdev);
> +		return;
> +	}
> +}
> +
> +void vexpress_config_of_populate(void)
> +{
> +	struct device_node *node;
> +
> +	for_each_matching_node(node, vexpress_config_devices_matches)
> +		vexpress_config_of_device_add(node);
> +}

This is unusual. Why do you only add the matching devices rather than
all of them? Doing it your way also means O(n^2) rather than O(n)
traversal through the list of children.

> +int vexpress_config_device_register(struct vexpress_config_device *vecdev)
> +{
> +	pr_debug("Registering %sdevice '%s." ADDR_FMT "'\n",
> +			vexpress_config_early ? "early " : "",
> +			vecdev->name, ADDR_ARGS(vecdev));
> +
> +	if (vecdev->addr.site == VEXPRESS_SITE_MASTER)
> +		vecdev->addr.site = vexpress_config_get_master_site();
> +
> +	if (!vecdev->bridge) {
> +		spin_lock(&vexpress_config_bridges_lock);
> +		vexpress_config_bridge_find(&vecdev->dev, NULL);
> +		spin_unlock(&vexpress_config_bridges_lock);
> +	}
> +
> +	if (vexpress_config_early) {
> +		list_add(&vecdev->early, &vexpress_config_early_devices);
> +		vexpress_config_early_bind();
> +
> +		return 0;
> +	}
> +
> +	device_initialize(&vecdev->dev);
> +	vecdev->dev.bus = &vexpress_config_bus_type;
> +	if (!vecdev->dev.parent)
> +		vecdev->dev.parent = &vexpress_config_bus;
> +
> +	dev_set_name(&vecdev->dev, "%s." ADDR_FMT,
> +			vecdev->name, ADDR_ARGS(vecdev));
> +
> +	return device_add(&vecdev->dev);
> +}
> +EXPORT_SYMBOL(vexpress_config_device_register);

Why is this exported to non-GPL drivers? It looks like the only caller should be
in this file.

	Arnd