本文主要分析:
1. i2c设备注册
2. i2c驱动注册
3. 上层调用过程
参考:
http://www.cnblogs.com/helloworldtoyou/p/5126618.html
1. i2c设备注册
kernel/arch/arm/mach-mx6/board-mx6q_sabresd.c
static void __init mx6_sabresd_board_init(void)
{
mxc_iomux_v3_setup_multiple_pads(mx6q_sabresd_pads, ---------------+
ARRAY_SIZE(mx6q_sabresd_pads)); |
... ... |
strcpy(mxc_i2c0_board_info[0].type, "wm8962"); |
mxc_i2c0_board_info[0].platform_data = &wm8962_config_data; |
|
//注册i2c总线 |
imx6q_add_imx_i2c(0, &mx6q_sabresd_i2c_data); ------------+ |
imx6q_add_imx_i2c(1, &mx6q_sabresd_i2c_data); ----+ | |
imx6q_add_imx_i2c(2, &mx6q_sabresd_i2c_data); | | |
| | |
i2c_register_board_info(0, mxc_i2c0_board_info, ----------------+ |
ARRAY_SIZE(mxc_i2c0_board_info)); | | | |
i2c_register_board_info(1, mxc_i2c1_board_info, | | | |
ARRAY_SIZE(mxc_i2c1_board_info)); | | | |
i2c_register_board_info(2, mxc_i2c2_board_info, | | | |
ARRAY_SIZE(mxc_i2c2_board_info)); | | | |
... ... | | | |
} | | | |
| | | |
static iomux_v3_cfg_t mx6q_sabresd_pads[] = { <----------|-----|--+
/* I2C1, WM8958 */ | | |
MX6Q_PAD_CSI0_DAT8__I2C1_SDA, | | |
MX6Q_PAD_CSI0_DAT9__I2C1_SCL, | | |
| | |
/* I2C2, Camera, MIPI */ | | |
MX6Q_PAD_KEY_COL3__I2C2_SCL, | | |
MX6Q_PAD_KEY_ROW3__I2C2_SDA, | | |
| | |
#ifdef CONFIG_MX6_ENET_IRQ_TO_GPIO | | |
MX6Q_PAD_GPIO_6__OBSERVE_MUX_OBSRV_INT_OUT1, | | |
#else | | |
/* I2C3 */ | | |
MX6Q_PAD_GPIO_3__I2C3_SCL, /* GPIO1[3] */ | | |
MX6Q_PAD_GPIO_6__I2C3_SDA, | | |
#endif | | |
}; | | |
| | |
//总线速率 V | |
static struct imxi2c_platform_data mx6q_sabresd_i2c_data = { | |
.bitrate = 100000, | |
}; | |
| |
#define imx6q_add_imx_i2c(id, pdata) <-----------+ |
imx_add_imx_i2c(&imx6q_imx_i2c_data[id], pdata) | |
| |
struct platform_device *__init imx_add_imx_i2c( <-----------+ |
const struct imx_imx_i2c_data *data, |
const struct imxi2c_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, |
}, |
}; |
|
return imx_add_platform_device("imx-i2c", data->id, |
res, ARRAY_SIZE(res), |
pdata, sizeof(*pdata)); |
} |
|
//指定i2c链接设备的名称,和地址 |
static struct i2c_board_info mxc_i2c0_board_info[] __initdata = { <-+
{ |
I2C_BOARD_INFO("wm89**", 0x1a), |
}, |
/* |
{ |
I2C_BOARD_INFO("ov564x", 0x3c), |
.platform_data = (void *)&camera_data, |
}, |
{ |
I2C_BOARD_INFO("mma8451", 0x1d), |
.platform_data = (void *)&mma8451_position, |
}, |
{ |
I2C_BOARD_INFO("isl1208", 0x6f), |
}, |
*/ |
}; |
|
int __init |
i2c_register_board_info(int busnum, <------------------+
struct i2c_board_info const *info, unsigned len)
{
int status;
down_write(&__i2c_board_lock);
//动态更新总线个数
/* dynamic bus numbers will be assigned after the last static one */
if (busnum >= __i2c_first_dynamic_bus_num)
__i2c_first_dynamic_bus_num = busnum + 1;
//将同一个i2c接口的所有设备都添加到一个链表中
for (status = 0; len; len--, info++) {
struct i2c_devinfo *devinfo;
devinfo = kzalloc(sizeof(*devinfo), GFP_KERNEL);
if (!devinfo) {
pr_debug("i2c-core: can't register boardinfo!
");
status = -ENOMEM;
break;
}
devinfo->busnum = busnum;
devinfo->board_info = *info;
list_add_tail(&devinfo->list, &__i2c_board_list);
}
up_write(&__i2c_board_lock);
return status;
}
2. i2c驱动注册
kernel/drivers/i2c/busses/i2c-imx.c
static int __init i2c_adap_imx_init(void)
{
return platform_driver_probe(&i2c_imx_driver, i2c_imx_probe); ----------+
} |
|
int __init_or_module platform_driver_probe(struct platform_driver *drv, |
int (*probe)(struct platform_device *)) |
{ |
int retval, code; |
|
drv->driver.suppress_bind_attrs = true; |
//指定驱动的probe函数 |
drv->probe = probe; |
//注册平台驱动 |
retval = code = platform_driver_register(drv); |
|
spin_lock(&drv->driver.bus->p->klist_drivers.k_lock); |
drv->probe = NULL; |
if (code == 0 && list_empty(&drv->driver.p->klist_devices.k_list)) |
retval = -ENODEV; |
drv->driver.probe = platform_drv_probe_fail; |
spin_unlock(&drv->driver.bus->p->klist_drivers.k_lock); |
|
if (code != retval) |
platform_driver_unregister(drv); |
return retval; |
} |
EXPORT_SYMBOL_GPL(platform_driver_probe); |
|
static struct platform_driver i2c_imx_driver = { <-----------------+
.remove = __exit_p(i2c_imx_remove), |
.driver = { |
.name = DRIVER_NAME, // "imx-i2c" |
.owner = THIS_MODULE, |
} |
}; |
|
static int __init i2c_imx_probe(struct platform_device *pdev) <---------+
{
struct imx_i2c_struct *i2c_imx;
struct resource *res;
struct imxi2c_platform_data *pdata;
void __iomem *base;
resource_size_t res_size;
int irq;
int ret;
dev_dbg(&pdev->dev, "<%s>
", __func__);
//获得i2c寄存器地址的信息
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res) {
dev_err(&pdev->dev, "can't get device resources
");
return -ENOENT;
}
irq = platform_get_irq(pdev, 0);
if (irq < 0) {
dev_err(&pdev->dev, "can't get irq number
");
return -ENOENT;
}
pdata = pdev->dev.platform_data;
if (pdata && pdata->init) {
ret = pdata->init(&pdev->dev);
if (ret)
return ret;
}
res_size = resource_size(res);
if (!request_mem_region(res->start, res_size, DRIVER_NAME)) {
ret = -EBUSY;
goto fail0;
}
base = ioremap(res->start, res_size);
if (!base) {
dev_err(&pdev->dev, "ioremap failed
");
ret = -EIO;
goto fail1;
}
i2c_imx = kzalloc(sizeof(struct imx_i2c_struct), GFP_KERNEL);
if (!i2c_imx) {
dev_err(&pdev->dev, "can't allocate interface
");
ret = -ENOMEM;
goto fail2;
}
/* Setup i2c_imx driver structure */
strcpy(i2c_imx->adapter.name, pdev->name);
i2c_imx->adapter.owner = THIS_MODULE;
i2c_imx->adapter.algo = &i2c_imx_algo; // i2c算法 ---------------+
i2c_imx->adapter.dev.parent = &pdev->dev; |
i2c_imx->adapter.nr = pdev->id; |
i2c_imx->irq = irq; |
i2c_imx->base = base; |
i2c_imx->res = res; |
|
/* Get I2C clock */ |
i2c_imx->clk = clk_get(&pdev->dev, "i2c_clk"); |
if (IS_ERR(i2c_imx->clk)) { |
ret = PTR_ERR(i2c_imx->clk); |
dev_err(&pdev->dev, "can't get I2C clock
"); |
goto fail3; |
} |
|
/* Request IRQ */ |
ret = request_irq(i2c_imx->irq, i2c_imx_isr, 0, pdev->name, i2c_imx); |
if (ret) { |
dev_err(&pdev->dev, "can't claim irq %d
", i2c_imx->irq); |
goto fail4; |
} |
|
/* Init queue */ |
init_waitqueue_head(&i2c_imx->queue); |
|
/* Set up adapter data */ |
i2c_set_adapdata(&i2c_imx->adapter, i2c_imx); |
|
/* Set up clock divider */ |
if (pdata && pdata->bitrate) |
i2c_imx_set_clk(i2c_imx, pdata->bitrate); |
else |
i2c_imx_set_clk(i2c_imx, IMX_I2C_BIT_RATE); |
|
/* Set up chip registers to defaults */ |
writeb(0, i2c_imx->base + IMX_I2C_I2CR); |
writeb(0, i2c_imx->base + IMX_I2C_I2SR); |
//添加adapter,一个i2c对应一个adapter |
/* Add I2C adapter */ |
ret = i2c_add_numbered_adapter(&i2c_imx->adapter); -----------------+ |
if (ret < 0) { | |
dev_err(&pdev->dev, "registration failed
"); | |
goto fail5; | |
} | |
| |
/* Set up platform driver data */ | |
platform_set_drvdata(pdev, i2c_imx); | |
| |
dev_dbg(&i2c_imx->adapter.dev, "claimed irq %d
", i2c_imx->irq); | |
dev_dbg(&i2c_imx->adapter.dev, "device resources from 0x%x to 0x%x
",| |
i2c_imx->res->start, i2c_imx->res->end); | |
dev_dbg(&i2c_imx->adapter.dev, "allocated %d bytes at 0x%x
", | |
res_size, i2c_imx->res->start); | |
dev_dbg(&i2c_imx->adapter.dev, "adapter name: "%s"
", | |
i2c_imx->adapter.name); | |
dev_dbg(&i2c_imx->adapter.dev, "IMX I2C adapter registered
"); | |
| |
return 0; /* Return OK */ | |
| |
fail5: | |
free_irq(i2c_imx->irq, i2c_imx); | |
fail4: | |
clk_put(i2c_imx->clk); | |
fail3: | |
kfree(i2c_imx); | |
fail2: | |
iounmap(base); | |
fail1: | |
release_mem_region(res->start, resource_size(res)); | |
fail0: | |
if (pdata && pdata->exit) | |
pdata->exit(&pdev->dev); | |
return ret; /* Return error number */ | |
} | |
| |
kernel/drivers/i2c/i2c-core.c | |
int i2c_add_numbered_adapter(struct i2c_adapter *adap) <----------+ |
{ |
int id; |
int status; |
|
if (adap->nr & ~MAX_ID_MASK) |
return -EINVAL; |
|
retry: |
if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0) |
return -ENOMEM; |
|
mutex_lock(&core_lock); |
/* "above" here means "above or equal to", sigh; |
* we need the "equal to" result to force the result |
*/ |
status = idr_get_new_above(&i2c_adapter_idr, adap, adap->nr, &id); |
if (status == 0 && id != adap->nr) { |
status = -EBUSY; |
idr_remove(&i2c_adapter_idr, id); |
} |
mutex_unlock(&core_lock); |
if (status == -EAGAIN) |
goto retry; |
|
if (status == 0) |
status = i2c_register_adapter(adap); ---------------+ |
return status; | |
} | |
EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter); | |
| |
static int i2c_register_adapter(struct i2c_adapter *adap) <--+ |
{ |
int res = 0; |
|
/* Can't register until after driver model init */ |
if (unlikely(WARN_ON(!i2c_bus_type.p))) { |
res = -EAGAIN; |
goto out_list; |
} |
|
/* Sanity checks */ |
if (unlikely(adap->name[0] == '