如何解决Linux x86 / ACPI中的Maxim MAX14830
尝试在CentOS8(x86_64)环境中加载Maxim MAX14830 SPI至QuadUART芯片时收到致命错误。使用的SPI控制器是Intel E3900 Atom,通过它我可以成功地使用SPIDEV进行安装和交互。
在回顾了ARM领域的一些示例之后,我认为问题在于我没有将“ clocks”参数传递给max310x驱动程序,但是我一直找不到合适的示例来描述“ phantom to the ACPI中的“ IC源时钟”。
芯片的时钟输入(引脚45,XIN)由运行在7.3728 MHz的标准时钟振荡器驱动。
DefinitionBlock ("e3900-spi.aml","SSDT",5,"INTEL","SPIDEV",1)
{
External (_SB_.PCI0.SPI1,DeviceObj)
Scope (\_SB.PCI0.SPI1)
{
Device (MAX1) {
Name (_HID,"PRP0001")
Name (_DDN,"Maxim MAX14380 Quad UART")
Name (_CRS,ResourceTemplate () {
SpiSerialBus (
0,// Chip select
PolarityLow,// Chip select is active low
FourWireMode,// Full duplex
8,// Bits per word is 8 (byte)
ControllerInitiated,// slave mode
1000000,// 1 MHz
ClockPolarityLow,// SPI mode 0
ClockPhaseFirst,// SPI mode 0
"\\_SB.PCI0.SPI1",// SPI host controller
0,// Must be 0
ResourceConsumer // Slave device
)
})
Name (_DSD,Package () {
ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),Package () {
Package () {"compatible","maxim,max14830"},Package () {"clock-names","osc"},Package () {"clock-frequency",7372800},Package () {"reg",0},}
})
}
Device (TP11) {
Name (_HID,"SPT0001")
Name (_DDN,"E3900-SPI1-CS1")
Name (_CRS,ResourceTemplate () {
SpiSerialBus (
1,// Don't care
1000000,// SPI host controller
0 // Must be 0
)
})
}
}
}
dmesg的相关输出为:
[ 1.974203] max310x spi-PRP0001:03: Cannot get clock
[ 1.975951] max310x: probe of spi-PRP0001:03 failed with error -22
该零件的数据表可以在这里找到:https://datasheets.maximintegrated.com/en/ds/MAX14830.pdf
任何指导或相关示例链接将不胜感激。谢谢!
编辑:我在https://www.kernel.org/doc/html/latest/firmware-guide/acpi/dsd/leds.html;找到了一个如何引用另一个对象的示例,以下AML正确编译,但导致内核崩溃。讨论(https://lore.kernel.org/lkml/914341e7-ca94-054d-6127-522b745006b4@arm.com/T/)使我相信ACPI不支持使用通用时钟框架,因此任何使用它的驱动程序都不能与ACPI + _DSD配置一起使用。
DefinitionBlock ("e3900-spi.aml",DeviceObj)
Scope (\_SB.PCI0.SPI1)
{
Device (CLK1) {
Name (_HID,"Maxim Clock Object")
Name (_DSD,"fixed-clock"},Package () {"clock-cells",}
})
}
Device (MAX1) {
Name (_HID,// slave mode
100000,// 100 kHz
ClockPolarityLow,Package () {"clocks",^CLK1},// SPI host controller
0 // Must be 0
)
})
}
}
}
解决方法
使用0andriy(https://lore.kernel.org/linux-serial/20201007084635.594991-1-andy.shevchenko@gmail.com/T/#u)提供的驱动程序更新,我可以使/ dev / ttyMAX设备出现,尽管我需要进行进一步的修改以强制振荡器计时。驱动程序仍然出现“无法获取时钟”错误。
我在此示例(https://github.com/westeri/meta-acpi/blob/master/recipes-bsp/acpi-tables/samples/edison/sc16is7xx.asl)之后对AML进行了建模,结果如下:
DefinitionBlock ("e3900-spi.aml","SSDT",5,"INTEL","SPI",1)
{
External (_SB_.PCI0.XHC_.RHUB.HS06.GPIO,DeviceObj)
External (_SB_.PCI0.SPI1,DeviceObj)
Scope (\_SB.PCI0.SPI1)
{
Device (MAX1) {
Name (_HID,"PRP0001")
Name (_DDN,"Maxim MAX14380 Quad UART")
Name (_CRS,ResourceTemplate () {
SpiSerialBus (
0,// Chip select
PolarityLow,// Chip select is active low
FourWireMode,// Full duplex
8,// Bits per word is 8 (byte)
ControllerInitiated,// slave mode
1000000,// 1 MHz
ClockPolarityLow,// SPI mode 0
ClockPhaseFirst,// SPI mode 0
"\\_SB.PCI0.SPI1",// SPI host controller
0,// Must be 0
ResourceConsumer // Slave device
)
GpioInt (Level,ActiveLow,Exclusive,PullDefault,0x0000,"\\_SB.PCI0.XHC.RHUB.HS06.GPIO",0x00,ResourceConsumer,) { 18 }
})
Name (_DSD,Package () {
ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),Package () {
Package () {"compatible","maxim,max14830"},Package () {"clock-frequency",7372800},}
})
}
}
}
但是,驱动程序仍然无法在devm_request_threaded_irq函数中运行:
[ 15.951778] max310x spi-PRP0001:00: MAX14830 ID: 0xb4
[ 15.965699] max310x spi-PRP0001:00: Reference clock set to 7372800 Hz
[ 15.968883] spi-PRP0001:00: ttyMAX0 at I/O 0x0 (irq = -517,base_baud = 460800) is a MAX14830
[ 15.972907] spi-PRP0001:00: ttyMAX1 at I/O 0x20 (irq = -517,base_baud = 460800) is a MAX14830
[ 15.985941] spi-PRP0001:00: ttyMAX2 at I/O 0x40 (irq = -517,base_baud = 460800) is a MAX14830
[ 15.990046] spi-PRP0001:00: ttyMAX3 at I/O 0x60 (irq = -517,base_baud = 460800) is a MAX14830
[ 16.009260] max310x spi-PRP0001:00: Unable to reguest IRQ -517
[ 16.021810] max310x: probe of spi-PRP0001:00 failed with error -22
作为C代码的新手,我无法找到一种方法来纠正此问题,最终仅对其进行注释,以使安装座不会自动拆除。
这时,我能够使用setserial实用程序成功查询它们并使用minicom访问设备。
[root@hwtest ~]# setserial -g /dev/ttyMAX*
/dev/ttyMAX0,UART: undefined,Port: 0x0000,IRQ: -517,Flags: low_latency
/dev/ttyMAX1,Port: 0x0020,Flags: low_latency
/dev/ttyMAX2,Port: 0x0040,Flags: low_latency
/dev/ttyMAX3,Port: 0x0060,Flags: low_latency
我将PCB交给EE来验证串行端口是否正常工作(它没有暴露简单的测试点),如果没有,我将更新此答案。
编辑:以这种方式配置后,我们能够发送数据,但是接收路径不起作用,可能是由于IRQ问题所致。我将使用5.11内核进行重新测试并进行报告。当前状态为LTS内核版本5.4.70,并已手动修补max310x驱动程序。
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