Re: [PATCH v6 09/30] PCI: Separate pci_host_bridge creation out of pci_create_root_bus()

[Bjorn Helgaas <bhelgaas@google.com>]

On Mon, Mar 09, 2015 at 10:34:06AM +0800, Yijing Wang wrote:
> This patch separate pci_host_bridge creation out
> of pci_create_root_bus(), and try to make a generic
> pci_host_bridge, then we could place generic PCI
> infos like domain number in it. Also Ripping out
> pci_host_bridge creation from pci_create_root_bus()
> make code more better readability. Further more,
> we could use the generic pci_host_bridge to hold
> host bridge specific operations like
> pcibios_root_bridge_prepare(). The changes are
> transparent to platform host bridge drivers.
> 
> Signed-off-by: Yijing Wang <wangyijing@huawei.com>
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
>  drivers/pci/host-bridge.c |   55 ++++++++++++++++++++++
>  drivers/pci/pci.h         |    3 +
>  drivers/pci/probe.c       |  114 ++++++++++++++++++++-------------------------
>  include/linux/pci.h       |    1 +
>  4 files changed, 109 insertions(+), 64 deletions(-)
> 
> diff --git a/drivers/pci/host-bridge.c b/drivers/pci/host-bridge.c
> index 39b2dbe..3bd45e7 100644
> --- a/drivers/pci/host-bridge.c
> +++ b/drivers/pci/host-bridge.c
> @@ -8,6 +8,61 @@
>  
>  #include "pci.h"
>  
> +static void pci_release_host_bridge_dev(struct device *dev)
> +{
> +	struct pci_host_bridge *bridge = to_pci_host_bridge(dev);
> +
> +	if (bridge->release_fn)
> +		bridge->release_fn(bridge);
> +
> +	pci_free_resource_list(&bridge->windows);
> +	kfree(bridge);
> +}
> +
> +struct pci_host_bridge *pci_create_host_bridge(
> +		struct device *parent, u32 db, struct list_head *resources)
> +{
> +	int error;
> +	int bus = PCI_BUSNUM(db);
> +	int domain = PCI_DOMAIN(db);
> +	struct pci_host_bridge *host;
> +	struct resource_entry *window, *n;
> +
> +	host = kzalloc(sizeof(*host), GFP_KERNEL);
> +	if (!host)
> +		return NULL;
> +
> +	host->busnum = bus;
> +	host->domain = domain;
> +	/* If support CONFIG_PCI_DOMAINS_GENERIC, use
> +	 * pci_host_assign_domain_nr() to assign domain
> +	 * number instead PCI_DOMAIN(db).
> +	 */

Follow the normal Linux comment style:

	host->domain = domain;

	/*
	 * If we support ...
	 */

> +	pci_host_assign_domain_nr(host);
> +
> +	host->dev.parent = parent;
> +	INIT_LIST_HEAD(&host->windows);
> +	host->dev.release = pci_release_host_bridge_dev;
> +	dev_set_name(&host->dev, "pci%04x:%02x", host->domain,
> +			host->busnum);
> +
> +	error = device_register(&host->dev);
> +	if (error) {
> +		put_device(&host->dev);
> +		return NULL;
> +	}
> +
> +	resource_list_for_each_entry_safe(window, n, resources)
> +		list_move_tail(&window->node, &host->windows);
> +
> +	return host;
> +}
> +
> +void pci_free_host_bridge(struct pci_host_bridge *host)
> +{
> +	device_unregister(&host->dev);
> +}
> +
>  static struct pci_bus *find_pci_root_bus(struct pci_bus *bus)
>  {
>  	while (bus->parent)
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index eeacab9..3de5e51 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -323,4 +323,7 @@ static inline int pci_dev_specific_reset(struct pci_dev *dev, int probe)
>  }
>  #endif
>  
> +struct pci_host_bridge *pci_create_host_bridge(
> +		struct device *parent, u32 dombus, struct list_head *resources);
> +void pci_free_host_bridge(struct pci_host_bridge *host);

A later patch adds another declaration and a blank line here.  If you want
the blank line, add it here, when you're adding the first declarations in
this section.

>  #endif /* DRIVERS_PCI_H */
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 3d6befd..27ec612 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -503,31 +503,6 @@ static struct pci_bus *pci_alloc_bus(struct pci_bus *parent)
>  	return b;
>  }
>  
> -static void pci_release_host_bridge_dev(struct device *dev)
> -{
> -	struct pci_host_bridge *bridge = to_pci_host_bridge(dev);
> -
> -	if (bridge->release_fn)
> -		bridge->release_fn(bridge);
> -
> -	pci_free_resource_list(&bridge->windows);
> -
> -	kfree(bridge);
> -}
> -
> -static struct pci_host_bridge *pci_alloc_host_bridge(struct pci_bus *b)
> -{
> -	struct pci_host_bridge *bridge;
> -
> -	bridge = kzalloc(sizeof(*bridge), GFP_KERNEL);
> -	if (!bridge)
> -		return NULL;
> -
> -	INIT_LIST_HEAD(&bridge->windows);
> -	bridge->bus = b;
> -	return bridge;
> -}
> -
>  static const unsigned char pcix_bus_speed[] = {
>  	PCI_SPEED_UNKNOWN,		/* 0 */
>  	PCI_SPEED_66MHz_PCIX,		/* 1 */
> @@ -1890,54 +1865,41 @@ void __weak pcibios_remove_bus(struct pci_bus *bus)
>  {
>  }
>  
> -struct pci_bus *pci_create_root_bus(struct device *parent, u32 db,
> -		struct pci_ops *ops, void *sysdata, struct list_head *resources)
> +static struct pci_bus *__pci_create_root_bus(
> +		struct pci_host_bridge *bridge, struct pci_ops *ops,
> +		void *sysdata)
>  {
>  	int error;
> -	struct pci_host_bridge *bridge;
>  	struct pci_bus *b, *b2;
> -	struct resource_entry *window, *n;
> +	struct resource_entry *window;
> +	struct device *parent;
>  	struct resource *res;
>  	resource_size_t offset;
>  	char bus_addr[64];
>  	char *fmt;
> -	u8	bus = PCI_BUSNUM(db);
>  
> +	parent = bridge->dev.parent;
>  	b = pci_alloc_bus(NULL);
>  	if (!b)
>  		return NULL;
>  
>  	b->sysdata = sysdata;
>  	b->ops = ops;
> -	b->number = b->busn_res.start = bus;
> +	b->number = b->busn_res.start = bridge->busnum;
>  	pci_bus_assign_domain_nr(b, parent);
> -	b2 = pci_find_bus(pci_domain_nr(b), bus);
> +	b2 = pci_find_bus(pci_domain_nr(b), b->number);
>  	if (b2) {
>  		/* If we already got to this bus through a different bridge, ignore it */
>  		dev_dbg(&b2->dev, "bus already known\n");
>  		goto err_out;
>  	}
>  
> -	bridge = pci_alloc_host_bridge(b);
> -	if (!bridge)
> -		goto err_out;
> -
> -	bridge->domain = PCI_DOMAIN(db);
> -	bridge->dev.parent = parent;
> -	bridge->dev.release = pci_release_host_bridge_dev;
> -	dev_set_name(&bridge->dev, "pci%04x:%02x", pci_domain_nr(b), bus);
> +	bridge->bus = b;
> +	b->bridge = get_device(&bridge->dev);
>  	error = pcibios_root_bridge_prepare(bridge);
> -	if (error) {
> -		kfree(bridge);
> +	if (error)
>  		goto err_out;
> -	}
>  
> -	error = device_register(&bridge->dev);
> -	if (error) {
> -		put_device(&bridge->dev);
> -		goto err_out;
> -	}
> -	b->bridge = get_device(&bridge->dev);
>  	device_enable_async_suspend(b->bridge);
>  	pci_set_bus_of_node(b);
>  
> @@ -1946,10 +1908,11 @@ struct pci_bus *pci_create_root_bus(struct device *parent, u32 db,
>  
>  	b->dev.class = &pcibus_class;
>  	b->dev.parent = b->bridge;
> -	dev_set_name(&b->dev, "%04x:%02x", pci_domain_nr(b), bus);
> +	dev_set_name(&b->dev, "%04x:%02x", bridge->domain,
> +			b->number);
>  	error = device_register(&b->dev);
>  	if (error)
> -		goto class_dev_reg_err;
> +		goto err_out;
>  
>  	pcibios_add_bus(b);
>  
> @@ -1962,12 +1925,11 @@ struct pci_bus *pci_create_root_bus(struct device *parent, u32 db,
>  		printk(KERN_INFO "PCI host bridge to bus %s\n", dev_name(&b->dev));
>  
>  	/* Add initial resources to the bus */
> -	resource_list_for_each_entry_safe(window, n, resources) {
> -		list_move_tail(&window->node, &bridge->windows);
> +	resource_list_for_each_entry(window, &bridge->windows) {
>  		res = window->res;
>  		offset = window->offset;
>  		if (res->flags & IORESOURCE_BUS)
> -			pci_bus_insert_busn_res(b, bus, res->end);
> +			pci_bus_insert_busn_res(b, b->number, res->end);
>  		else
>  			pci_bus_add_resource(b, res, 0);
>  		if (offset) {
> @@ -1989,14 +1951,23 @@ struct pci_bus *pci_create_root_bus(struct device *parent, u32 db,
>  
>  	return b;
>  
> -class_dev_reg_err:
> -	put_device(&bridge->dev);
> -	device_unregister(&bridge->dev);
>  err_out:
>  	kfree(b);
>  	return NULL;
>  }
>  
> +struct pci_bus *pci_create_root_bus(struct device *parent, u32 db,
> +		struct pci_ops *ops, void *sysdata, struct list_head *resources)
> +{
> +	struct pci_host_bridge *host;
> +
> +	host = pci_create_host_bridge(parent, db, resources);
> +	if (!host)
> +		return NULL;
> +
> +	return __pci_create_root_bus(host, ops, sysdata);
> +}
> +
>  int pci_bus_insert_busn_res(struct pci_bus *b, int bus, int bus_max)
>  {
>  	struct resource *res = &b->busn_res;
> @@ -2060,29 +2031,32 @@ void pci_bus_release_busn_res(struct pci_bus *b)
>  			res, ret ? "can not be" : "is");
>  }
>  
> -struct pci_bus *pci_scan_root_bus(struct device *parent, u32 db,
> -		struct pci_ops *ops, void *sysdata, struct list_head *resources)
> +static struct pci_bus *__pci_scan_root_bus(
> +		struct pci_host_bridge *host, struct pci_ops *ops,
> +		void *sysdata)
>  {
>  	struct resource_entry *window;
>  	bool found = false;
>  	struct pci_bus *b;
>  	int max;
>  
> -	resource_list_for_each_entry(window, resources)
> +	resource_list_for_each_entry(window, &host->windows)
>  		if (window->res->flags & IORESOURCE_BUS) {
>  			found = true;
>  			break;
>  		}
>  
> -	b = pci_create_root_bus(parent, db, ops, sysdata, resources);
> -	if (!b)
> +	b = __pci_create_root_bus(host, ops, sysdata);
> +	if (!b) {
> +		pci_free_host_bridge(host);
>  		return NULL;
> +	}
>  
>  	if (!found) {
>  		dev_info(&b->dev,
>  		 "No busn resource found for root bus, will use [bus %02x-ff]\n",
> -			PCI_BUSNUM(db));
> -		pci_bus_insert_busn_res(b, PCI_BUSNUM(db), 255);
> +			host->busnum);
> +		pci_bus_insert_busn_res(b, b->number, 255);
>  	}
>  
>  	max = pci_scan_child_bus(b);
> @@ -2092,6 +2066,18 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, u32 db,
>  
>  	return b;
>  }
> +
> +struct pci_bus *pci_scan_root_bus(struct device *parent, u32 db,
> +		struct pci_ops *ops, void *sysdata, struct list_head *resources)
> +{
> +	struct pci_host_bridge *host;
> +
> +	host = pci_create_host_bridge(parent, db, resources);
> +	if (!host)
> +		return NULL;
> +
> +	return __pci_scan_root_bus(host, ops, sysdata);
> +}
>  EXPORT_SYMBOL(pci_scan_root_bus);
>  
>  struct pci_bus *pci_scan_bus(u32 db, struct pci_ops *ops,
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 2b1b998..463eaa3 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -402,6 +402,7 @@ static inline int pci_channel_offline(struct pci_dev *pdev)
>  
>  struct pci_host_bridge {
>  	u16	domain;
> +	u16 busnum;

Why do we need this?  host_bridge->bus->number and
host_bridge->bus->busn_res.start both already contain the same information,
and I hate to add a third place.  I know pci_create_host_bridge() doesn't
have a struct pci_bus at the point where you initialize busnum, but it does
have the resource list, which contains the bus number range.

>  	struct device dev;
>  	struct pci_bus *bus;		/* root bus */
>  	struct list_head windows;	/* resource_entry */
> -- 
> 1.7.1
>