Subject: [RFC PATCH 08/16] PCI: Introduce pci_scan_host_bridge() and pci_host_info

From: [email-masked] (Yijing Wang)
Date: Wed, 19 Nov 2014 10:09:12 +0800

>>  struct pci_host_bridge *pci_create_host_bridge(
>> -		struct device *parent, u32 db, 
>> -		struct pci_ops *ops, void *sysdata, 
>> -		struct list_head *resources)
>> +		struct device *parent, u32 db, struct pci_ops *ops, 
>> +		struct pci_host_info *info)
>>  {
>>  	int error;
>>  	struct pci_bus *b;
>>  	struct pci_host_bridge *host, *h;
>> -	struct pci_host_bridge_window *window, *n;
>>  
>>  	down_read(&pci_host_bridge_sem);
>>  	list_for_each_entry(h, &pci_host_bridge_list, list) {
>> @@ -53,7 +51,7 @@ struct pci_host_bridge *pci_create_host_bridge(
>>  	if (!host)
>>  		return NULL;
>>  
>> -	host->sysdata = sysdata;
>> +	host->sysdata = info->arg;
>>  	host->busnum = PCI_BUSNUM(db);
>>  	host->domain = PCI_DOMAIN(db);
>>  	host->ops = ops;
>> @@ -63,18 +61,23 @@ struct pci_host_bridge *pci_create_host_bridge(
>>  
>>  	/* this is hack, just for build, will be removed later*/
> 
> Why do you need this hack? Just for calling pci_domain_nr() ?

Yes, it's temporary code, we need domain number here for pci host bridge register.

> 
>>  	b = kzalloc(sizeof(*b), GFP_KERNEL);
>> -	b->sysdata = sysdata;
>> +	b->sysdata = host->sysdata;
>>  	pci_bus_assign_domain_nr(b, parent);
>>  	host->domain = pci_domain_nr(b);
>> +	kfree(b);
>>  
...
>> +static int pci_default_init_res(struct pci_host_bridge *host,
>> +		struct pci_host_info *info)
>> +{
>> +	struct pci_host_bridge_window *window, *n;
>> +
>> +	if (info->res_type != PCI_HOST_RES_DEFAULT) 
>> +		list_for_each_entry_safe(window, n, info->resources,
>> +				list)
>> +			list_move_tail(&window->list, &host->windows);
>> +	else
>> +		info->res_type = PCI_HOST_RES_DEFAULT;
> 
> I'm confused about this assignment. Isn't this a nop as the else part
> means info->res_type *is* PCI_HOST_RES_DEFAULT?

No, in this patch, host drivers pass a pci host bridge resources init hook
in pci_host_info *info, and we call this info->init_res() in pci_create_host_bridge().

+struct pci_host_info {
+	u8 res_type;
+	void *arg;
+	struct list_head *resources; /*just for build, will clean up later */
+	int (*init_res)(struct pci_host_bridge *host,
+			struct pci_host_info *info);
+};
+

>> +
>> +	return 0;
>> +}
...
>> @@ -2038,8 +2057,13 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, u32 db,
>>  	bool found = false;
>>  	struct pci_host_bridge *host;
>>  	int max;
>> +	struct pci_host_info info;
>> +	
>> +	info.arg = sysdata;
>> +	info.resources = resources;
>> +	info.init_res = pci_default_init_res;
> 
> I have mixed feelings about this patch. While it is heading in the right direction
> of moving pci_host_bridge relevant information towards the right user, I don't think
> you picked up the right set to move. The resource list is going to be copied into
> internal pci_host_bridge list anyway, keeping another copy is not helpful *and*
> you have increased the code size.
> 
> I think for now we should aim to get the *missing* data into pci_host_bridge: MSI
> controllers and PCI domain/segment. Then we can do more cleanup.

Hi Liviu, I agree with you here, the changes to resources stuff seems not a perfect
solution. In my patch 6, we could pass pci domain nr by u32 PCI_DOMBUS(domain, bus) argument,
and store it in pci_host_bridge. For msi controller, we couldn't save the msi_controller
in pci_host_bridge. Before we assume one pci host bridge only had one msi_controller,
but now something changes, Jiang introduce hierarchy irq domain in x86, and now
one pci host bridge may has more than one msi_controller. So I prefer to add a
function to pci_host_bridge something like

struct msi_controller *pci_get_msi_controller(struct pci_dev *dev)

> 
>>  
>> -	host = pci_create_host_bridge(parent, db, ops, sysdata, resources);
>> +	host = pci_create_host_bridge(parent, db, ops, &info);
>>  	if (!host)
>>  		return NULL;
>>  
>> @@ -2070,6 +2094,47 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, u32 db,
>>  }
>>  EXPORT_SYMBOL(pci_scan_root_bus);
>>  
>> +struct pci_host_bridge *pci_scan_host_bridge(
>> +		struct device *parent, u32 db, struct pci_ops *ops,
>> +		struct pci_host_info *info)
>> +{
>> +	struct pci_host_bridge_window *window;
>> +	bool found = false;
>> +	struct pci_host_bridge *host;
>> +	int max;
>> +
>> +	host = pci_create_host_bridge(parent, db, ops, info);
>> +	if (!host)
>> +		return NULL;
>> +
>> +	list_for_each_entry(window, &host->windows, list)
>> +		if (window->res->flags & IORESOURCE_BUS) {
>> +			found = true;
>> +			break;
>> +		}
>> +
>> +	host->bus = __pci_create_root_bus(host);
>> +	if (!host->bus) {
>> +		pci_free_host_bridge(host);
>> +		return NULL;
>> +	}
>> +
>> +	if (!found) {
>> +		dev_info(&host->bus->dev,
>> +		 "No busn resource found for root bus, will use [bus %02x-ff]\n",
>> +			host->busnum);
>> +		pci_bus_insert_busn_res(host->bus, host->busnum, 255);
>> +	}
>> +
>> +	max = pci_scan_child_bus(host->bus);
>> +	if (!found)
>> +		pci_bus_update_busn_res_end(host->bus, max);
>> +
>> +	return host;
>> +
>> +}
>> +EXPORT_SYMBOL(pci_scan_host_bridge);
>> +
>>  /**
>>   * pci_rescan_bus_bridge_resize - scan a PCI bus for devices.
>>   * @bridge: PCI bridge for the bus to scan
>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>> index daa7f40..a51f5f5 100644
>> --- a/include/linux/pci.h
>> +++ b/include/linux/pci.h
>> @@ -412,6 +412,21 @@ struct pci_host_bridge {
>>  	void *release_data;
>>  };
>>  
>> +struct pci_host_info {
>> +	u8 res_type;
>> +	void *arg;
>> +	struct list_head *resources; /*just for build, will clean up later */
>> +	int (*init_res)(struct pci_host_bridge *host, 
>> +			struct pci_host_info *info);
>> +};
>> +
>> +static inline void init_pci_host_info(struct pci_host_info *info)
>> +{
>> +	memset(info, 0 , sizeof(*info));
>> +}
> 
> Where is this used?

Host driver uses it to init pci_host_info.

> 
>> +
>> +#define PCI_HOST_RES_DEFAULT	0x2
>> +
> 
> Magic number?

Hmmm, I will rework pci host bridge resources stuff.

> 
> Best regards,
> Liviu
> 
>>  #define	to_pci_host_bridge(n) container_of(n, struct pci_host_bridge, dev)
>>  void pci_set_host_bridge_release(struct pci_host_bridge *bridge,
>>  		     void (*release_fn)(struct pci_host_bridge *),
>> @@ -420,7 +435,7 @@ void pci_set_host_bridge_release(struct pci_host_bridge *bridge,
>>  int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge);
>>  struct pci_host_bridge *pci_create_host_bridge(
>>  		struct device *parent, u32 db, struct pci_ops *ops, 
>> -		void *sys, struct list_head *resources);
>> +		struct pci_host_info *info);
>>  /*
>>   * The first PCI_BRIDGE_RESOURCE_NUM PCI bus resources (those that correspond
>>   * to P2P or CardBus bridge windows) go in a table.  Additional ones (for
>> @@ -785,6 +800,9 @@ void pci_bus_release_busn_res(struct pci_bus *b);
>>  struct pci_bus *pci_scan_root_bus(struct device *parent, u32 bus,
>>  					     struct pci_ops *ops, void *sysdata,
>>  					     struct list_head *resources);
>> +struct pci_host_bridge *pci_scan_host_bridge(struct device *parent,
>> +		u32 db, struct pci_ops *ops,
>> +		struct pci_host_info *info);
>>  struct pci_bus *pci_add_new_bus(struct pci_bus *parent, struct pci_dev *dev,
>>  				int busnr);
>>  void pcie_update_link_speed(struct pci_bus *bus, u16 link_status);
>> -- 
>> 1.7.1
>>
>> --
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> 

-- 
Thanks!
Yijing