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

[Liviu Dudau <Liviu.Dudau@arm.com>]

On Mon, Nov 17, 2014 at 10:21:42AM +0000, Yijing Wang wrote:
> From: Yijing Wang <wangyijing0307@gmail.com>
> 
> Now pci_host_bridge has been ripped out from pci root
> bus creation. Currently pci_scan_root_bus() lacks
> scalability, so platform host drivers have no proper
> way to configure pci_host_bridge. E.g we should assign
> msi_controller to pci_host_bridge, add argument for
> pci_scan_root_bus() is not a good idea, it has already
> five, so introudce struct pci_host_info to make
> pci scan interfaces more scalable. Because almost
> all host drivers need to configure host resources,
> so we put .init_res() in it first, and add other
> hooks when need.
> 
> Signed-off-by: Yijing Wang <wangyijing@huawei.com>
> ---
>  drivers/pci/host-bridge.c |   27 +++++++++-------
>  drivers/pci/probe.c       |   73 ++++++++++++++++++++++++++++++++++++++++++--
>  include/linux/pci.h       |   20 ++++++++++++-
>  3 files changed, 103 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/pci/host-bridge.c b/drivers/pci/host-bridge.c
> index e31604f..49b6c21 100644
> --- a/drivers/pci/host-bridge.c
> +++ b/drivers/pci/host-bridge.c
> @@ -8,9 +8,6 @@
>  
>  #include "pci.h"
>  
> -LIST_HEAD(pci_host_bridge_list);
> -DECLARE_RWSEM(pci_host_bridge_sem);
> -
>  static struct resource busn_resource = {
>  	.name	= "PCI busn",
>  	.start	= 0,
> @@ -18,6 +15,9 @@ static struct resource busn_resource = {
>  	.flags	= IORESOURCE_BUS,
>  };
>  
> +LIST_HEAD(pci_host_bridge_list);
> +DECLARE_RWSEM(pci_host_bridge_sem);
> +
>  static void pci_release_host_bridge_dev(struct device *dev)
>  {
>  	struct pci_host_bridge *bridge = to_pci_host_bridge(dev);
> @@ -29,14 +29,12 @@ static void pci_release_host_bridge_dev(struct device *dev)
>  }
>  
>  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() ?

>  	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);
>  
> -	if (!resources) {
> +	if (info->res_type == PCI_HOST_RES_DEFAULT) {
>  		/* Use default IO/MEM/BUS resources*/
>  		pci_add_resource(&host->windows, &ioport_resource);
>  		pci_add_resource(&host->windows, &iomem_resource);
>  		pci_add_resource(&host->windows, &busn_resource);
>  	} else {
> -		list_for_each_entry_safe(window, n, resources, list)
> -			list_move_tail(&window->list, &host->windows);
> +		if (!info->init_res || info->init_res(host, info)) {
> +			pr_err("pci host %04x:%02x init resources fail\n",
> +					host->domain, host->busnum);
> +			kfree(host);
> +			return NULL;
> +		}
>  	}
>  
>  	dev_set_name(&host->dev, "pci%04x:%02x", host->domain, 
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index d472da4..42158fd 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1863,6 +1863,21 @@ void __weak pcibios_remove_bus(struct pci_bus *bus)
>  {
>  }
>  
> +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?

> +
> +	return 0;
> +}
> +
>  struct pci_bus *__pci_create_root_bus(struct pci_host_bridge *bridge)
>  {
>  	int error;
> @@ -1949,13 +1964,17 @@ err_out:
>  	return NULL;
>  }
>  
> -struct pci_bus *pci_create_root_bus(struct device *parent, u32 bus,
> +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;
> +	struct pci_host_info info;
> +	
> +	info.arg= sysdata;
> +	info.resources = resources;
> +	info.init_res = pci_default_init_res;
>  
> -	host = pci_create_host_bridge(parent, bus, ops, 
> -			sysdata ,resources);
> +	host = pci_create_host_bridge(parent, db, ops, &info);
>  	if (!host)
>  		return NULL;
>  
> @@ -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.

>  
> -	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?

> +
> +#define PCI_HOST_RES_DEFAULT	0x2
> +

Magic number?

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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