Openwrt的不同版本中关于MT7628，MT7688的GPIO配置，存在或多或少的一些小问题
下面将以MT7628AN为基础，介绍其全部的GPIO功能复用配置，以及需要注意的地方
MT76x8一个就47个可作为GPIO引脚，如下
关于其全部的功能复用表可以参考MTK官方的开发demo版Linkit
在这全部的引脚中，需要特别注意的是：
1. 网口模式，因为MTK的设计，一共5个网口，要么全部作为普通网口使用，要么只有一个网口（Port0），没有中间选项；
因此，如果需要用到UART2，SDCARD等功能时，系统只剩一个P0网口可用，这也是MTK所宣传的IOT模式
2. SPI接口，datasheet介绍可以作为GPIO使用，但是因为大多系统都接了SPI NOR Flash，因此其不能设置为GPIO模式；而SPI_CS1另一个SPI片选脚，倒是不受影响，可作为GPIO
3. 关于GPIO/GPO的描述，比如I2C的两个脚是GPO，但经实际测试，描述为GPO的其实可以作为输入使用
static struct rt2880_pmx_group mt7628an_pinmux_data[] = {
GRP_G("pwm1", pwm1_grp_mt7628, MT7628_GPIO_MODE_MASK,
1, MT7628_GPIO_MODE_PWM1),
GRP_G("pwm0", pwm0_grp_mt7628, MT7628_GPIO_MODE_MASK,
1, MT7628_GPIO_MODE_PWM0),
GRP_G("uart2", uart2_grp_mt7628, MT7628_GPIO_MODE_MASK,
1, MT7628_GPIO_MODE_UART2),
GRP_G("uart1", uart1_grp_mt7628, MT7628_GPIO_MODE_MASK,
1, MT7628_GPIO_MODE_UART1),
GRP_G("i2c", i2c_grp_mt7628, MT7628_GPIO_MODE_MASK,
1, MT7628_GPIO_MODE_I2C),
GRP("refclk", refclk_grp_mt7628, 1, MT7628_GPIO_MODE_REFCLK),
GRP("perst", perst_grp_mt7628, 1, MT7628_GPIO_MODE_PERST),
GRP("wdt", wdt_grp_mt7628, 1, MT7628_GPIO_MODE_WDT),
GRP("spi", spi_grp_mt7628, 1, MT7628_GPIO_MODE_SPI),
GRP_G("sdmode", sd_mode_grp_mt7628, MT7628_GPIO_MODE_MASK,
1, MT7628_GPIO_MODE_SDMODE),
GRP_G("uart0", uart0_grp_mt7628, MT7628_GPIO_MODE_MASK,
1, MT7628_GPIO_MODE_UART0),
GRP_G("i2s", i2s_grp_mt7628, MT7628_GPIO_MODE_MASK,
1, MT7628_GPIO_MODE_I2S),
GRP_G("spi cs1", spi_cs1_grp_mt7628, MT7628_GPIO_MODE_MASK,
1, MT7628_GPIO_MODE_CS1),
GRP_G("spis", spis_grp_mt7628, MT7628_GPIO_MODE_MASK,
1, MT7628_GPIO_MODE_SPIS),
GRP_G("gpio", gpio_grp_mt7628, MT7628_GPIO_MODE_MASK,
1, MT7628_GPIO_MODE_GPIO),
GRP_G("wled_an", wled_an_grp_mt7628, MT7628_GPIO_MODE_MASK,
1, MT7628_GPIO_MODE_WLED_AN)
}在DTS文件中，填写对应的name和func名字就可以，如：
pinctrl {
state_default: pinctrl0 {
gpio {
ralink,group = "gpio","wled_an", "i2s", "refclk", "perst", "wdt", "spi cs1";
ralink,function = "gpio";
};
}
UART1开启：
uart1@d00 {
status = "okay";
};
SPI_CS1 开启，使用系统spi控制器，注意pinctrl-0 = <&spi_pins>, <&spi_cs1_pins>，配置CS1为SPI_CS1功能，同时应该去掉pinctrl0中"spi cs1"的GPIO复用
spi@b00 {
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&spi_pins>, <&spi_cs1_pins>;
spidev@1 {
#address-cells = <1>;
#size-cells = <1>;
compatible = "spidev";
reg = <1 0>;
spi-max-frequency = <40000000>;
};
}GPIO模拟SPI配置，如：使用I2S的复用脚0-3，注意先配置I2S为GPIO模式
spi-gpio {
compatible = "spi-gpio";
#address-cells = <0x1>;
cs-gpios = <&gpio0 2 0>;
gpio-sck = <&gpio0 0 0>;
gpio-mosi = <&gpio0 3 0>;
gpio-miso = <&gpio0 1 0>;
num-chipselects = <1>;
spidev@0 {
#address-cells = <0x1>;
compatible = "spidev";
spi-max-frequency = <10000000>;
reg = <0>;
};
};
I2C的RTC时钟配置，以PCF8563为例，注意reg地址的问题，pcf8563地址是0x51，常用的ds1307是0x68
i2c@900 {
status = "okay";
rtc@51 {
compatible = "nxp,pcf8563";
reg = <0x51>;
};
};LED配置参考，注意MT76x8有两组GPIO，GPIO0对应0-31，GPIO1对应32-46
gpio-leds {
compatible = "gpio-leds";
modpwr {
label = "modpwr";
gpios = <&gpio1 8 1>;
};
modrst {
label = "modrst";
gpios = <&gpio1 4 0>;
};
heart {
label = "heart";
gpios = <&gpio1 6 1>;
};
}lable对应运行系统中/sys/class/leds/lable/brightness 的lable名字
gpios = <&gpio1 8 1>; 表示GPIO1组，8 表示 32+8 即GPIO40，1表示低电平有效，即默认输出高电平
按键配置参考，
gpio-keys-polled {
compatible = "gpio-keys-polled";
#address-cells = <1>;
#size-cells = <0>;
poll-interval = <20>;
vccin {
label = "BTN_0";
gpios = <&gpio0 6 0>;
linux,code = <0x100>;
};
reset {
label = "reset";
gpios = <&gpio1 7 1>;
linux,code = <0x198>;
};
};
poll-interval 表示输入检测消抖时间，label对应于运行系统中/etc/rc.button/lable，即按键后对应的执行脚本文件，如上述配置，系统中应该存在reset和BTN_0两个脚本， gpios同LED说明
linux,code = <0x198>; 对应input.h的宏定义值，配合驱动文件gpio-button-hotplug.c中的相关配置，如：
static struct bh_map button_map[] = {
BH_MAP(BTN_0, "BTN_0"),
BH_MAP(BTN_1, "BTN_1"),
BH_MAP(BTN_2, "BTN_2"),
BH_MAP(BTN_3, "BTN_3"),
BH_MAP(BTN_4, "BTN_4"),
BH_MAP(BTN_5, "BTN_5"),
BH_MAP(BTN_6, "BTN_6"),
BH_MAP(BTN_7, "BTN_7"),
BH_MAP(BTN_8, "BTN_8"),
BH_MAP(BTN_9, "BTN_9"),
BH_MAP(KEY_POWER, "power"),
BH_MAP(KEY_RESTART, "reset"),
BH_MAP(KEY_RFKILL, "rfkill"),
BH_MAP(KEY_WPS_BUTTON, "wps"),
BH_MAP(KEY_WIMAX, "wwan"),
};其原理是gpio-button-hotplug驱动会检测按键事件，然后通过netlionk方式广播出来，proc会一直监测事件，触发hotplug，进而执行到相关reset等脚本，热拔插事件也是此类方式，具体不再详细介绍，本文主要介绍引脚复用配置
另，还需注意的是，配置了相关引脚功能后，还需在kernel中开启相关驱动模块以及选择相关的应用才能正常使用
到此，常用接口基本介绍完毕
1. 看门狗dts 地址错误，位置：target/linux/ramips/dts/mt7628an.dtsi
watchdog: watchdog@100 {
compatible = "ralink,mt7628an-wdt", "mediatek,mt7621-wdt";
reg = <0x100 0x30>;
resets = <&rstctrl 8>;
reset-names = "wdt";
interrupt-parent = <&intc>;
interrupts = <24>;
};根据DataSheet，watchdog的偏移地址应该是100
同时，如果需要自行喂狗的话，注意先关闭proc进程中自动喂狗功能
2. REFCLK，PERST的配置错误，位置arch/mips/ralink/mt7620.c，原来的reclk和perst引脚配置反了
static struct rt2880_pmx_func refclk_grp_mt7628[] = { FUNC("reclk", 0, 37, 1) };
static struct rt2880_pmx_func perst_grp_mt7628[] = { FUNC("perst", 0, 36, 1) };3. PHY 0-4的LED不能作为GPIO的问题，参考补丁文件：
--- a/arch/mips/ralink/mt7620.c 2018-09-04 17:14:33.000000000 +0800
+++ b/arch/mips/ralink/mt7620.c 2018-04-09 08:28:51.000000000 +0800
@@ -138,8 +138,8 @@
FUNC("i2c", 0, 4, 2),
};
-static struct rt2880_pmx_func refclk_grp_mt7628[] = { FUNC("reclk", 0, 36, 1) };
-static struct rt2880_pmx_func perst_grp_mt7628[] = { FUNC("perst", 0, 37, 1) };
+static struct rt2880_pmx_func refclk_grp_mt7628[] = { FUNC("reclk", 0, 37, 1) };
+static struct rt2880_pmx_func perst_grp_mt7628[] = { FUNC("perst", 0, 36, 1) };
static struct rt2880_pmx_func wdt_grp_mt7628[] = { FUNC("wdt", 0, 38, 1) };
static struct rt2880_pmx_func spi_grp_mt7628[] = { FUNC("spi", 0, 7, 4) };
@@ -185,23 +185,50 @@
FUNC("gpio", 0, 11, 1),
};
-static struct rt2880_pmx_func wled_kn_grp_mt7628[] = {
- FUNC("rsvd", 3, 35, 1),
- FUNC("rsvd", 2, 35, 1),
- FUNC("gpio", 1, 35, 1),
- FUNC("wled_kn", 0, 35, 1),
+struct rt2880_pmx_func wled_an_grp_mt7628[] = {
+ FUNC("rsvd", 3, 44, 1),
+ FUNC("rsvd", 2, 44, 1),
+ FUNC("gpio", 1, 44, 1),
+ FUNC("wled_an", 0,44, 1),
+};
+
+static struct rt2880_pmx_func ephy_p0_grp_mt7628[] = {
+ FUNC("rsvd", 3, 43, 1),
+ FUNC("rsvd", 2, 43, 1),
+ FUNC("gpio", 1, 43, 1),
+ FUNC("ephy", 0, 43, 1),
+};
+
+static struct rt2880_pmx_func ephy_p1_grp_mt7628[] = {
+ FUNC("rsvd", 3, 42, 1),
+ FUNC("rsvd", 2, 42, 1),
+ FUNC("gpio", 1, 42, 1),
+ FUNC("ephy", 0, 42, 1),
+};
+static struct rt2880_pmx_func ephy_p2_grp_mt7628[] = {
+ FUNC("rsvd", 3, 41, 1),
+ FUNC("rsvd", 2, 41, 1),
+ FUNC("gpio", 1, 41, 1),
+ FUNC("ephy", 0, 41, 1),
+};
+static struct rt2880_pmx_func ephy_p3_grp_mt7628[] = {
+ FUNC("rsvd", 3, 40, 1),
+ FUNC("rsvd", 2, 40, 1),
+ FUNC("gpio", 1, 40, 1),
+ FUNC("ephy", 0, 40, 1),
+};
+static struct rt2880_pmx_func ephy_p4_grp_mt7628[] = {
+ FUNC("rsvd", 3, 39, 1),
+ FUNC("rsvd", 2, 39, 1),
+ FUNC("gpio", 1, 39, 1),
+ FUNC("ephy", 0, 39, 1),
};
-
-static struct rt2880_pmx_func wled_an_grp_mt7628[] = {
- FUNC("rsvd", 3, 44, 1),
- FUNC("rsvd", 2, 44, 1),
- FUNC("gpio", 1, 44, 1),
- FUNC("wled_an", 0, 44, 1),
-};
-
#define MT7628_GPIO_MODE_MASK 0x3
-
-#define MT7628_GPIO_MODE_WLED_KN 48
+#define MT7628_GPIO_MODE_EPHY_P4 42
+#define MT7628_GPIO_MODE_EPHY_P3 40
+#define MT7628_GPIO_MODE_EPHY_P2 38
+#define MT7628_GPIO_MODE_EPHY_P1 36
+#define MT7628_GPIO_MODE_EPHY_P0 34
#define MT7628_GPIO_MODE_WLED_AN 32
#define MT7628_GPIO_MODE_PWM1 30
#define MT7628_GPIO_MODE_PWM0 28
@@ -236,7 +263,12 @@
GRP_G("spis", spis_grp_mt7628, MT7628_GPIO_MODE_MASK, 1, MT7628_GPIO_MODE_SPIS),
GRP_G("gpio", gpio_grp_mt7628, MT7628_GPIO_MODE_MASK, 1, MT7628_GPIO_MODE_GPIO),
GRP_G("wled_an", wled_an_grp_mt7628, MT7628_GPIO_MODE_MASK, 1, MT7628_GPIO_MODE_WLED_AN),
- GRP_G("wled_kn", wled_kn_grp_mt7628, MT7628_GPIO_MODE_MASK, 1, MT7628_GPIO_MODE_WLED_KN),
+ GRP_G("ephy_p0", ephy_p0_grp_mt7628, MT7628_GPIO_MODE_MASK, 1, MT7628_GPIO_MODE_EPHY_P0),
+ GRP_G("ephy_p1", ephy_p1_grp_mt7628, MT7628_GPIO_MODE_MASK, 1, MT7628_GPIO_MODE_EPHY_P1),
+ GRP_G("ephy_p2", ephy_p2_grp_mt7628, MT7628_GPIO_MODE_MASK, 1, MT7628_GPIO_MODE_EPHY_P2),
+ GRP_G("ephy_p3", ephy_p3_grp_mt7628, MT7628_GPIO_MODE_MASK, 1, MT7628_GPIO_MODE_EPHY_P3),
+ GRP_G("ephy_p4", ephy_p4_grp_mt7628, MT7628_GPIO_MODE_MASK, 1, MT7628_GPIO_MODE_EPHY_P4),
+
{ 0 }
};