上一篇中，我们分析了request_mem_region的实现。
现在来看看board文件中是如何配置ssi和esai的。
现在做的项目是基于freescale平台的。
所以代码也是基于该平台代码进行分析。
先看看ssi。
首先定义了一个mxc_audio_platform_data结构体和一个platform_device结构体：
static struct mxc_audio_platform_data XXXX_data[] = {
{
.ssi_num = 1,
.src_port = 2,
.ext_port = 5,
.init = xxxx_init0,
.hp_gpio = -1,
},
};
static struct platform_device xxxx_device = {
.name = "xxxx",
};
/*
* This struct is to define the number of SSIs on a platform,
* DAM source port config, DAM external port config,
* regulator names, and other stuff audio needs.
*/
struct mxc_audio_platform_data {
int ssi_num;
int src_port;
int ext_port;
int intr_id_hp;
int ext_ram;
struct clk *ssi_clk[2];
int hp_gpio;
int hp_active_low; /* headphone irq is active low */
int mic_gpio;
int mic_active_low; /* micphone irq is active low */
int sysclk;
const char *codec_name;
int (*init) (void); /* board specific init */
int (*amp_enable) (int enable);
int (*clock_enable) (int enable);
int (*finit) (void); /* board specific finit */
void *priv; /* used by board specific functions */
};
struct platform_device {
const char * name;
int id;
struct device dev;
u32 num_resources;
struct resource * resource;
const struct platform_device_id *id_entry;
/* MFD cell pointer */
struct mfd_cell *mfd_cell;
/* arch specific additions */
struct pdev_archdata archdata;
};
然后调用mxc_register_device将上面定义的两个结构体进行注册。
mxc_register_device的实现：
int __init mxc_register_device(struct platform_device *pdev, void *data)
{
int ret;
// data即是前面的XXXX_data。pdev即是前面的xxxx_device
pdev->dev.platform_data = data;
/×
/**
* platform_device_register - add a platform-level device
* @pdev: platform device we're adding
*/
int platform_device_register(struct platform_device *pdev)
{
device_initialize(&pdev->dev);
return platform_device_add(pdev);
}
/**
* device_initialize - init device structure.
* @dev: device.
*
* This prepares the device for use by other layers by initializing
* its fields.
* It is the first half of device_register(), if called by
* that function, though it can also be called separately, so one
* may use @dev's fields. In particular, get_device()/put_device()
* may be used for reference counting of @dev after calling this
* function.
*
* NOTE: Use put_device() to give up your reference instead of freeing
* @dev directly once you have called this function.
*/
void device_initialize(struct device *dev)
{
dev->kobj.kset = devices_kset;
kobject_init(&dev->kobj, &device_ktype);
INIT_LIST_HEAD(&dev->dma_pools);
mutex_init(&dev->mutex);
lockdep_set_novalidate_class(&dev->mutex);
spin_lock_init(&dev->devres_lock);
INIT_LIST_HEAD(&dev->devres_head);
// device_pm_init - Initialize the PM-related part of a device object.
device_pm_init(dev);
set_dev_node(dev, -1);
}
static inline void set_dev_node(struct device *dev, int node)
{
dev->numa_node = node;
}
/**
* platform_device_add - add a platform device to device hierarchy
* @pdev: platform device we're adding
*
* This is part 2 of platform_device_register(), though may be called
* separately _iff_ pdev was allocated by platform_device_alloc().
*/
int platform_device_add(struct platform_device *pdev)
{
int i, ret = 0;
if (!pdev)
return -EINVAL;
if (!pdev->dev.parent)
pdev->dev.parent = &platform_bus;
pdev->dev.bus = &platform_bus_type;
// 前面只指定了pdev->name没有指定pdev->id
if (pdev->id != -1)
dev_set_name(&pdev->dev, "%s.%d", pdev->name, pdev->id);
else
dev_set_name(&pdev->dev, "%s", pdev->name);
for (i = 0; i < pdev->num_resources; i++) {
struct resource *p, *r = &pdev->resource[i];
if (r->name == NULL)
r->name = dev_name(&pdev->dev);
// 上一篇中，已经分析过resource的父子关系
p = r->parent;
if (!p) {
if (resource_type(r) == IORESOURCE_MEM)
p = &iomem_resource;
else if (resource_type(r) == IORESOURCE_IO)
p = &ioport_resource;
}
// 将resource添加到resource tree中。
/×
/**
* insert_resource - Inserts a resource in the resource tree
* @parent: parent of the new resource
* @new: new resource to insert
*
* Returns 0 on success, -EBUSY if the resource can't be inserted.
*/
int insert_resource(struct resource *parent, struct resource *new)
{
struct resource *conflict;
/×
/**
* insert_resource_conflict - Inserts resource in the resource tree
* @parent: parent of the new resource
* @new: new resource to insert
*
* Returns 0 on success, conflict resource if the resource can't be inserted.
*
* This function is equivalent to request_resource_conflict when no conflict
* happens. If a conflict happens, and the conflicting resources
* entirely fit within the range of the new resource, then the new
* resource is inserted and the conflicting resources become children of
* the new resource.
*/
struct resource *insert_resource_conflict(struct resource *parent, struct resource *new)
{
struct resource *conflict;
write_lock(&resource_lock);
conflict = __insert_resource(parent, new);
write_unlock(&resource_lock);
return conflict;
}
×/
conflict = insert_resource_conflict(parent, new);
return conflict ? -EBUSY : 0;
}
×/
if (p && insert_resource(p, r)) {
printk(KERN_ERR
"%s: failed to claim resource %d\n",
dev_name(&pdev->dev), i);
ret = -EBUSY;
goto failed;
}
}
pr_debug("Registering platform device '%s'. Parent at %s\n",
dev_name(&pdev->dev), dev_name(pdev->dev.parent));
ret = device_add(&pdev->dev);
if (ret == 0)
return ret;
failed:
while (--i >= 0) {
struct resource *r = &pdev->resource[i];
unsigned long type = resource_type(r);
if (type == IORESOURCE_MEM || type == IORESOURCE_IO)
release_resource(r);
}
return ret;
}
×/
ret = platform_device_register(pdev);
if (ret)
pr_debug("Unable to register platform device '%s': %d\n",
pdev->name, ret);
return ret;
}
接下来定义了imx_add_platform_device结构体：
static struct imx_ssi_platform_data xxx_ssi0_pdata = {
.flags = IMX_SSI_DMA | IMX_SSI_SYN,
};
然后调用imx6q_add_imx_ssi进行注册：
imx6q_add_imx_ssi(0, &xxx_ssi0_pdata);
imx6q_add_imx_ssi的实现：
#define imx6q_add_imx_ssi(id, pdata) \ imx_add_imx_ssi(&imx6_imx_ssi_data[id], pdata)
其中imx6_imx_ssi_data的定义：
const struct imx_imx_ssi_data imx6_imx_ssi_data[] __initconst = {
#define imx6q_imx_ssi_data_entry(_id, _hwid) \
imx_imx_ssi_data_entry(MX6Q, _id, _hwid, SZ_4K)
imx6q_imx_ssi_data_entry(0, 1),
imx6q_imx_ssi_data_entry(1, 2),
imx6q_imx_ssi_data_entry(2, 3),
};
#define imx_imx_ssi_data_entry(soc, _id, _hwid, _size) \
[_id] = { \
.id = _id, \
.iobase = soc ## _SSI ## _hwid ## _BASE_ADDR, \
.iosize = _size, \
.irq = soc ## _INT_SSI ## _hwid, \
.dmatx0 = soc ## _DMA_REQ_SSI ## _hwid ## _TX0, \
.dmarx0 = soc ## _DMA_REQ_SSI ## _hwid ## _RX0, \
.dmatx1 = soc ## _DMA_REQ_SSI ## _hwid ## _TX1, \
.dmarx1 = soc ## _DMA_REQ_SSI ## _hwid ## _RX1, \
}
soc ## _SSI ## _hwid ## _BASE_ADDR拼出来其实是：
MX6Q_SSI1_BASE_ADDR
MX6Q_SSI2_BASE_ADDR
MX6Q_SSI3_BASE_ADDR
看看它们的定义：
#define MX6Q_SSI1_BASE_ADDR (ATZ1_BASE_ADDR + 0x28000) /* slot 10 */ #define MX6Q_SSI2_BASE_ADDR (ATZ1_BASE_ADDR + 0x2C000) /* slot 11 */ #define MX6Q_SSI3_BASE_ADDR (ATZ1_BASE_ADDR + 0x30000) /* slot 12 */
与data sheet中一致。
再看imx_add_imx_ssi的实现：
struct platform_device *__init imx_add_imx_ssi(
const struct imx_imx_ssi_data *data,
const struct imx_ssi_platform_data *pdata)
{
struct resource res[] = {
{
.start = data->iobase,
.end = data->iobase + data->iosize - 1,
.flags = IORESOURCE_MEM,
}, {
.start = data->irq,
.end = data->irq,
.flags = IORESOURCE_IRQ,
},
#define DMARES(_name) { \
.name = #_name, \
.start = data->dma ## _name, \
.end = data->dma ## _name, \
.flags = IORESOURCE_DMA, \
}
DMARES(tx0),
DMARES(rx0),
DMARES(tx1),
DMARES(rx1),
};
// data->id是0.res就是前面定义的。pdata就是xxx_ssi0_pdata
return imx_add_platform_device("imx-ssi", data->id,
res, ARRAY_SIZE(res),
pdata, sizeof(*pdata));
}
static inline struct platform_device *imx_add_platform_device(
const char *name, int id,
const struct resource *res, unsigned int num_resources,
const void *data, size_t size_data)
{
return imx_add_platform_device_dmamask(
name, id, res, num_resources, data, size_data, 0);
}
struct platform_device *__init imx_add_platform_device_dmamask(
const char *name, int id,
const struct resource *res, unsigned int num_resources,
const void *data, size_t size_data, u64 dmamask)
{
int ret = -ENOMEM;
struct platform_device *pdev;
/**
* platform_device_alloc - create a platform device
* @name: base name of the device we're adding
* @id: instance id
*
* Create a platform device object which can have other objects attached
* to it, and which will have attached objects freed when it is released.
*/
pdev = platform_device_alloc(name, id);
if (!pdev)
goto err;
if (dmamask) {
/*
* This memory isn't freed when the device is put,
* I don't have a nice idea for that though. Conceptually
* dma_mask in struct device should not be a pointer.
* See http://thread.gmane.org/gmane.linux.kernel.pci/9081
*/
pdev->dev.dma_mask =
kmalloc(sizeof(*pdev->dev.dma_mask), GFP_KERNEL);
if (!pdev->dev.dma_mask)
/* ret is still -ENOMEM; */
goto err;
*pdev->dev.dma_mask = dmamask;
pdev->dev.coherent_dma_mask = dmamask;
}
/×
/**
* platform_device_add_resources - add resources to a platform device
* @pdev: platform device allocated by platform_device_alloc to add resources to
* @res: set of resources that needs to be allocated for the device
* @num: number of resources
*
* Add a copy of the resources to the platform device. The memory
* associated with the resources will be freed when the platform device is
* released.
*/
int platform_device_add_resources(struct platform_device *pdev,
const struct resource *res, unsigned int num)
{
struct resource *r = NULL;
if (res) {
r = kmemdup(res, sizeof(struct resource) * num, GFP_KERNEL);
if (!r)
return -ENOMEM;
}
kfree(pdev->resource);
pdev->resource = r;
pdev->num_resources = num;
return 0;
}
×/
if (res) {
// 此处add的resource在ssi的probe函数中调用platform_get_resource可以获取。
// platform_get_resource(pdev, IORESOURCE_MEM, 0)
ret = platform_device_add_resources(pdev, res, num_resources);
if (ret)
goto err;
}
/*
/**
* platform_device_add_data - add platform-specific data to a platform device
* @pdev: platform device allocated by platform_device_alloc to add resources to
* @data: platform specific data for this platform device
* @size: size of platform specific data
*
* Add a copy of platform specific data to the platform device's
* platform_data pointer. The memory associated with the platform data
* will be freed when the platform device is released.
*/
int platform_device_add_data(struct platform_device *pdev, const void *data,
size_t size)
{
void *d = NULL;
if (data) {
d = kmemdup(data, size, GFP_KERNEL);
if (!d)
return -ENOMEM;
}
kfree(pdev->dev.platform_data);
pdev->dev.platform_data = d;
return 0;
}
*/
if (data) {
ret = platform_device_add_data(pdev, data, size_data);
if (ret)
goto err;
}
ret = platform_device_add(pdev);
if (ret) {
err:
if (dmamask)
kfree(pdev->dev.dma_mask);
platform_device_put(pdev);
return ERR_PTR(ret);
}
return pdev;
}
从上面的代码看，imx6_imx_ssi_data只有3个成员。
当调用
imx6q_add_imx_ssi(3, &mx6_smartauto_ssi3_pdata);
时，访问了imx6_imx_ssi_data[3]，超出了数组的界限。
难道刚好esai的data数组刚好在ssi的后面，所以imx6_imx_ssi_data[3]其实访问的是esai的数组？
但是为什么probe中打印出来的resource name是ssi-0呢？
看了下前面data数组的定义，其中没有name相关的内容。
再看res数组的定义，也没有name。
所以imx6_imx_ssi_data[3]访问了esai的data数组，但是data数组中并没有name信息，所以name还为ssi-0。
这个name从哪儿来的呢？
又看了一遍代码，也没发现哪儿对resource name进行赋值。