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devm_ioremap_resource [2018/07/30 16:40]
rpjday [Broadcom Cygnus]
devm_ioremap_resource [2018/07/31 11:59] (current)
rpjday [platform_get_resource()]
Line 1: Line 1:
 ===== Overview ===== ===== Overview =====
  
-Explain ''​devm_ioremap_resource()'',​ with examples. Add some links.+Explain ''​devm_ioremap_resource()'',​ with examples ​particularly related to memory regions. Add some links.
  
-===== Let's talk about resources ===== +===== struct resource ​=====
- +
-==== struct resource ====+
  
 From ''​include/​linux/​ioport.h'',​ a device can have a number of resources of different types: From ''​include/​linux/​ioport.h'',​ a device can have a number of resources of different types:
Line 24: Line 22:
 </​code>​ </​code>​
  
- +In particular, one resource ​type is a memory range (''​flags''​ of ''​IORESOURCE_MEM''​):​
-A small sample of resource ​types from that same file (''​IORESOURCE_MEM'' ​is the one representing physical memory that many drivers are interested in):+
  
 <​code>​ <​code>​
Line 40: Line 37:
 </​code>​ </​code>​
  
-==== struct platform_device ====+Here's a single example from ''​arch/​arm/​mach-davinci/​dm355.c'',​ defining an array of resources:
  
-From ''​include/​linux/​platform_device.h'':​+<​code>​ 
 +static struct resource edma_resources[] = { 
 +        { 
 +                .name   = "​edma3_cc",​ 
 +                .start ​ = 0x01c00000,​ 
 +                .end    = 0x01c00000 + SZ_64K - 1, 
 +                .flags ​ = IORESOURCE_MEM,​ 
 +        }, 
 +        { 
 +                .name   = "​edma3_tc0",​ 
 +                .start ​ = 0x01c10000,​ 
 +                .end    = 0x01c10000 + SZ_1K - 1, 
 +                .flags ​ = IORESOURCE_MEM,​ 
 +        }, 
 +        { 
 +                .name   = "​edma3_tc1",​ 
 +                .start ​ = 0x01c10400,​ 
 +                .end    = 0x01c10400 + SZ_1K - 1, 
 +                .flags ​ = IORESOURCE_MEM,​ 
 +        }, 
 +        ... snip ... 
 +</​code>​ 
 +===== struct platform_device ===== 
 + 
 +From ''​include/​linux/​platform_device.h''​, showing how a ''​platform_device''​ can represent any number of resources:
  
 <​code>​ <​code>​
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 ===== platform_get_resource() ===== ===== platform_get_resource() =====
  
-From ''​drivers/​base/​platform.c'',​ given a platform device ​and a resource type, return that resource type or ''​NULL'':​+From ''​drivers/​base/​platform.c'',​ given a ''​struct platform_device *dev'' ​and a resource type, return that (numbered) ​resource type or ''​NULL'':​
  
 <​code>​ <​code>​
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  return NULL;  return NULL;
 } }
 +</​code>​
 +
 +You can also get a resource by an optional name:
 +
 +<​code>​
 +/**
 + * platform_get_resource_byname - get a resource for a device by name
 + * @dev: platform device
 + * @type: resource type
 + * @name: resource name
 + */
 +struct resource *platform_get_resource_byname(struct platform_device *dev,
 +                                              unsigned int type,
 +                                              const char *name)
 +{
 +        int i;
 +
 +        for (i = 0; i < dev->​num_resources;​ i++) {
 +                struct resource *r = &​dev->​resource[i];​
 +
 +                if (unlikely(!r->​name))
 +                        continue;
 +
 +                if (type == resource_type(r) && !strcmp(r->​name,​ name))
 +                        return r;
 +        }
 </​code>​ </​code>​
  
devm_ioremap_resource.1532968803.txt.gz · Last modified: 2018/07/30 16:40 by rpjday