當flag為IORESOURCE_MEM時，start、end表示platform device使用的記憶體開始位址和結束位址‧
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
當flag為IORESOURCE_IRQ時，start、end表示platform device使用的中斷號的開始值和結束值‧
res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
2. include/linux/ioport.h
/*
* Resources are tree-like, allowing
* nesting etc..
*/
struct resource {
resource_size_t start;
resource_size_t end;
const char *name;
unsigned long flags;
struct resource *parent, *sibling, *child;
};
/*
* IO resources have these defined flags.
*/
#define IORESOURCE_BITS 0x000000ff /* Bus-specific bits */
#define IORESOURCE_TYPE_BITS 0x00001f00 /* Resource type */
#define IORESOURCE_IO 0x00000100 /* PCI/ISA I/O ports */
#define IORESOURCE_MEM 0x00000200
#define IORESOURCE_REG 0x00000300 /* Register offsets */
#define IORESOURCE_IRQ 0x00000400
#define IORESOURCE_DMA 0x00000800
#define IORESOURCE_BUS 0x00001000
#define IORESOURCE_PREFETCH 0x00002000 /* No side effects */
#define IORESOURCE_READONLY 0x00004000
#define IORESOURCE_CACHEABLE 0x00008000
#define IORESOURCE_RANGELENGTH 0x00010000
#define IORESOURCE_SHADOWABLE 0x00020000
#define IORESOURCE_SIZEALIGN 0x00040000 /* size indicates alignment */
#define IORESOURCE_STARTALIGN 0x00080000 /* start field is alignment */
#define IORESOURCE_MEM_64 0x00100000
#define IORESOURCE_WINDOW 0x00200000 /* forwarded by bridge */
#define IORESOURCE_MUXED 0x00400000 /* Resource is software muxed */
#define IORESOURCE_EXCLUSIVE 0x08000000 /* Userland may not map this resource */
#define IORESOURCE_DISABLED 0x10000000
#define IORESOURCE_UNSET 0x20000000 /* No address assigned yet */
#define IORESOURCE_AUTO 0x40000000
#define IORESOURCE_BUSY 0x80000000 /* Driver has marked this resource busy */
3. 當resouce中定義了兩個以上的記憶體空間和一個中斷號資源
/* device tree 定義方式 */
test: test@09100000 {
compatible = "uio";
reg = <0x09100000 0x10000>,
<0x09200000 0x10000>;
interrupts = <0 29 0x4>;
};
/* 結構定義方式 */
static struct resource cns3xxx_usb_ehci_resources[] = {
[0] = {
.start = CNS3XXX_USB0_BASE,
.end = CNS3XXX_USB0_BASE + SZ_16M - 1,
.flags = IORESOURCE_MEM,
},
[1] = {
.start = CNS3XXX_USB1_BASE,
.end = CNS3XXX_USB1_BASE + SZ_16M - 1,
.flags = IORESOURCE_MEM,
},
[2] = {
.start = IRQ_CNS3XXX_USB_EHCI,
.flags = IORESOURCE_IRQ,
},
};
可透過platform_get_resouice第三個參數指定index
res = platform_get_resource(pdev, IORESOURCE_MEM, 0); res = platform_get_resource(pdev, IORESOURCE_MEM, 1); res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);4. 在使用IRQ資源，platform_get_irq封裝了platform_get_resource，也可以使用platform_get_irq(struct platform_device *dev, unsigned int num);去取得中斷號資源，
drivers/base/platform.c
/**
* platform_get_resource - get a resource for a device
* @dev: platform device
* @type: resource type
* @num: resource index
*/
struct resource *platform_get_resource(struct platform_device *dev,
unsigned int type, unsigned int num)
{
int i;
for (i = 0; i < dev->num_resources; i++) {
struct resource *r = &dev->resource[i];
if (type == resource_type(r) && num-- == 0)
return r;
}
return NULL;
}
EXPORT_SYMBOL_GPL(platform_get_resource);
/**
* platform_get_irq - get an IRQ for a device
* @dev: platform device
* @num: IRQ number index
*/
int platform_get_irq(struct platform_device *dev, unsigned int num)
{
#ifdef CONFIG_SPARC
/* sparc does not have irqs represented as IORESOURCE_IRQ resources */
if (!dev || num >= dev->archdata.num_irqs)
return -ENXIO;
return dev->archdata.irqs[num];
#else
struct resource *r;
if (IS_ENABLED(CONFIG_OF_IRQ) && dev->dev.of_node) {
int ret;
ret = of_irq_get(dev->dev.of_node, num);
if (ret >= 0 || ret == -EPROBE_DEFER)
return ret;
}
r = platform_get_resource(dev, IORESOURCE_IRQ, num);
/*
* The resources may pass trigger flags to the irqs that need
* to be set up. It so happens that the trigger flags for
* IORESOURCE_BITS correspond 1-to-1 to the IRQF_TRIGGER*
* settings.
*/
if (r && r->flags & IORESOURCE_BITS)
irqd_set_trigger_type(irq_get_irq_data(r->start),
r->flags & IORESOURCE_BITS);
return r ? r->start : -ENXIO;
#endif
}
5. 範例
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
struct sample_timer {
void __iomem *base;
void __iomem *memory;
int irq;
};
static int sample_probe(struct platform_device *pdev)
{
struct resource *base_res, *memory_res;
static struct sample_timer *timer;
pr_alert("%s\n", __FUNCTION__);
timer = devm_kzalloc(&pdev->dev, sizeof(struct sample_timer), GFP_KERNEL);
if (NULL == timer) {
dev_err(&pdev->dev, "cannot allocate memory\n");
return -ENOMEM;
}
base_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (NULL == base_res) {
dev_err(&pdev->dev, "cannot get IORESOUCE_MEM\n");
return -ENOENT;
}
memory_res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
if (NULL == memory_res) {
dev_err(&pdev->dev, "cannot get IORESOUCE_MEM\n");
return -ENOENT;
}
timer->base = devm_ioremap_resource(&pdev->dev, base_res);
timer->memory = devm_ioremap_resource(&pdev->dev, memory_res);
if ((IS_ERR((const void *)(timer->base))) || (IS_ERR((const void *)(timer->memory)))) {
dev_err(&pdev->dev, "cannot get ioremap\n");
return -ENOENT;
}
timer->irq = platform_get_irq(pdev, 0);
if (timer->irq < 0) {
dev_err(&pdev->dev, "no irq specified\n");
return -ENOENT;
}
return 0;
}
static int sample_remove(struct platform_device *pdev)
{
return 0;
}
#define sample_suspend NULL
#define sample_resume NULL
static const struct of_device_id sample_dt_ids[] = {
{.compatible = "sample,timer",},
{ }
};
MODULE_DEVICE_TABLE(of, sample_dt_ids);
static struct platform_driver sample_driver = {
.probe = sample_probe,
.remove = sample_remove,
.suspend = sample_suspend,
.resume = sample_resume,
.driver = {
.name = "sample",
.owner = THIS_MODULE,
.of_match_table = sample_dt_ids,
},
};
static int __init sample_init(void)
{
int ret;
ret = platform_driver_register(&sample_driver);
return ret;
}
static void __exit sample_exit(void)
{
platform_driver_unregister(&sample_driver);
}
module_init(sample_init);
module_exit(sample_exit);
MODULE_AUTHOR("Allen");
MODULE_DESCRIPTION("sample");
MODULE_LICENSE("GPL");
6. 參考來源platform设备驱动全透析 http://www.bianceng.cn/OS/Linux/201301/34910_3.htm
