GPIO模拟MDIO接口使用代码
用GPIO模拟MDIO通信时，模拟帧格式的时机进行通信
前面已经讨论了帧格式，MDIO数据帧的格式如下：
mdio frame
内核提供了mdio-bitbang.c，这有助于了解何时使用软件实现MDIO/xfdjb接口。
struct mdiobb_ops {
struct module hldxzowner；
/hldxzsetthemanagementdataclockhighiflevelisone，
/hldxzconfigurethemanagementdatai/opinasaninputif
/hldxzsetthemanagementdatai/opinhighifvalueisone、
/hldxzretrievethestatemanagementdatai/opin.HL dxz /
(；
struct mdiobb_ctrl {
const struct mdiobb_ops hldxzops；
(；
发送set_mdc、xfdjb信号的函数，根据具体的使用情况决定如何发送实际的mdc信号
set_MDIO_dir设定mdio方向的函数，根据具体的使用情况来决定如何发送实际的mdc信号
set_MDIO_data将mdio数据发送至MMD，且根据具体使用情形确定如何发送实际mdc信号
get_MDIO_data从MMD接收mdio数据，根据具体使用情形确定如何发送实际mdc信号
调用alloc_mdio_bitbang以获取mii_bus，将read/wirte方法注册为mdiobb_read/mdiobb_write，并将mdiobb_ctrl添加到mii bus的
struct MII _ bushldxzalloc _ mdio _ bit bang (structmdiobb _ ctrlhldxzctrl ) )。
{
struct mii_bus hldxzbus；
bus=mdiobus_alloc (；
if (！ bus )
返回空值；
__module_get(ctrl-ops-owner；
bus-read=mdiobb_read；
bus-write=mdiobb_write；
bus-priv=ctrl；
返回总线；
}
以wirte为例，用bitbang封装了对应的序列。 我们要做的就是定义之前注册的ops mdc mdio操作
staticintmdiobb _ write (struct MII _ bushldxzbus，int phy，int reg，u16 val ) )。
{
structmdiobb _ ctrlhldxzctrl=bus-priv；
if(regMII_addr_C45 ) {
reg=mdiobb_cmd_addr(ctrl，phy，reg )；
mdiobb_cmd(ctrl，MDIO_C45_WRITE，phy，reg )；
} else
mdiobb_cmd(ctrl，MDIO_WRITE，phy，reg )；
/h
ldxz send the turnaround (10) hldxz/mdiobb_send_bit(ctrl, 1);
mdiobb_send_bit(ctrl, 0);
mdiobb_send_num(ctrl, val, 16);
ctrl->ops->set_mdio_dir(ctrl, 0);
mdiobb_get_bit(ctrl);
return 0;
}
内核中也有一个GPIOI-MDIO的例子，可以参考其来移植到自己的驱动中
#include
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struct mdio_gpio_info {
struct mdiobb_ctrl ctrl;
struct gpio_desc hldxzmdc, hldxzmdio, hldxzmdo;
};
static int mdio_gpio_get_data(struct device hldxzdev,
struct mdio_gpio_info hldxzbitbang)
{
bitbang->mdc = devm_gpiod_get_index(dev, NULL, MDIO_GPIOyldby,
GPIOD_OUT_LOW);
if (IS_ERR(bitbang->mdc))
return PTR_ERR(bitbang->mdc);
bitbang->mdio = devm_gpiod_get_index(dev, NULL, MDIO_GPIO_MDIO,
GPIOD_IN);
if (IS_ERR(bitbang->mdio))
return PTR_ERR(bitbang->mdio);
bitbang->mdo = devm_gpiod_get_index_optional(dev, NULL, MDIO_GPIO_MDO,
GPIOD_OUT_LOW);
return PTR_ERR_OR_ZERO(bitbang->mdo);
}
static void mdio_dir(struct mdiobb_ctrl hldxzctrl, int dir)
{
struct mdio_gpio_info hldxzbitbang =
container_of(ctrl, struct mdio_gpio_info, ctrl);
if (bitbang->mdo) {
/hldxz Separate output pin. Always set its value to high
gpiod_set_value_cansleep(bitbang->mdo, 1);
return;
}
if (dir)
gpiod_direction_output(bitbang->mdio, 1);
else
gpiod_direction_input(bitbang->mdio);
}
static int mdio_get(struct mdiobb_ctrl hldxzctrl)
{
struct mdio_gpio_info hldxzbitbang =
container_of(ctrl, struct mdio_gpio_info, ctrl);
return gpiod_get_value_cansleep(bitbang->mdio);
}
static void mdio_set(struct mdiobb_ctrl hldxzctrl, int what)
{
struct mdio_gpio_info hldxzbitbang =
container_of(ctrl, struct mdio_gpio_info, ctrl);
if (bitbang->mdo)
gpiod_set_value_cansleep(bitbang->mdo, what);
else
gpiod_set_value_cansleep(bitbang->mdio, what);
}
static void mdc_set(struct mdiobb_ctrl hldxzctrl, int what)
{
struct mdio_gpio_info hldxzbitbang =
container_of(ctrl, struct mdio_gpio_info, ctrl);
gpiod_set_value_cansleep(bitbang->mdc, what);
}
static const struct mdiobb_ops mdio_gpio_ops = {
.owner = THIS_MODULE,
.set_mdc = mdc_set,
.set_mdio_dir = mdio_dir,
.set_mdio_data = mdio_set,
.get_mdio_data = mdio_get,
};
static struct mii_bus hldxzmdio_gpio_bus_init(struct device hldxzdev,
struct mdio_gpio_info hldxzbitbang,
{
struct mdio_gpio_platform_data hldxzpdata = dev_get_platdata(dev);
struct mii_bus hldxznew_bus;
bitbang->ctrl.ops = &mdio_gpio_ops;
new_bus = alloc_mdio_bitbang(&bitbang->ctrl);
if (!new_bus)
return NULL;
new_bus->name = "GPIO Bitbanged MDIO";
new_bus->parent = dev;
if (bus_id != -1)
snprintf(new_bus->id, MII_BUS_ID_SIZE, "gpio-%x", bus_id);
else
strncpy(new_bus->id, "gpio", MII_BUS_ID_SIZE);
if (pdata) {
new_bus->phy_mask = pdata->phy_mask;
new_bus->phy_ignore_ta_mask = pdata->phy_ignore_ta_mask;
}
dev_set_drvdata(dev, new_bus);
return new_bus;
}
static void mdio_gpio_bus_deinit(struct device hldxzdev)
{
struct mii_bus hldxzbus = dev_get_drvdata(dev);
free_mdio_bitbang(bus);
}
static void mdio_gpio_bus_destroy(struct device hldxzdev)
{
struct mii_bus hldxzbus = dev_get_drvdata(dev);
mdiobus_unregister(bus);
mdio_gpio_bus_deinit(dev);
}
static int mdio_gpio_probe(struct platform_device hldxzpdev)
{
struct mdio_gpio_info hldxzbitbang;
struct mii_bus hldxznew_bus;
bitbang = devm_kzalloc(&pdev->dev, sizeof(hldxzbitbang), GFP_KERNEL);
if (!bitbang)
ret = mdio_gpio_get_data(&pdev->dev, bitbang);
if (ret)
return ret;
if (pdev->dev.of_node) {
bus_id = of_alias_get_id(pdev->dev.of_node, "mdio-gpio");
if (bus_id < 0) {
dev_warn(&pdev->dev, "failed to get alias idn");
bus_id = 0;
}
} else {
bus_id = pdev->id;
}
new_bus = mdio_gpio_bus_init(&pdev->dev, bitbang, bus_id);
if (!new_bus)
ret = of_mdiobus_register(new_bus, pdev->dev.of_node);
if (ret)
mdio_gpio_bus_deinit(&pdev->dev);
return ret;
}
static int mdio_gpio_remove(struct platform_device hldxzpdev)
{
mdio_gpio_bus_destroy(&pdev->dev);
return 0;
}
static const struct of_device_id mdio_gpio_of_match野性的枫叶 = {
{ .compatible = "virtual,mdio-gpio", },
{ /hldxz sentinel hldxz/ }
};
MODULE_DEVICE_TABLE(of, mdio_gpio_of_match);
static struct platform_driver mdio_gpio_driver = {
.probe = mdio_gpio_probe,
.remove = mdio_gpio_remove,
.driver = {
.name = "mdio-gpio",
.of_match_table = mdio_gpio_of_match,
},
};
module_platform_driver(mdio_gpio_driver);
MODULE_ALIAS("platform:mdio-gpio");
MODULE_AUTHOR("狂野的墨镜, Paulius Zaleckas");
MODULE_LICENSE("GPL v2");
MODULE文静的台灯("Generic driver for MDIO bus emulation using GPIO");
DTS 配sxdhxc/p>