diff options
Diffstat (limited to 'src/soc/amd')
| -rw-r--r-- | src/soc/amd/common/block/include/amdblocks/espi.h | 44 |
1 files changed, 37 insertions, 7 deletions
diff --git a/src/soc/amd/common/block/include/amdblocks/espi.h b/src/soc/amd/common/block/include/amdblocks/espi.h index 971768853a..296ae4e1e3 100644 --- a/src/soc/amd/common/block/include/amdblocks/espi.h +++ b/src/soc/amd/common/block/include/amdblocks/espi.h @@ -36,13 +36,43 @@ #define ESPI_OOB_CH_EN (1 << 1) #define ESPI_FLASH_CH_EN (1 << 0) -/* Virtual wire interrupt polarity. eSPI interrupts are active level high signals. The - polarity register inverts the incoming signal if the associated bit with the irq is - 0. */ -#define ESPI_VW_IRQ_LEVEL_HIGH(x) (1 << (x)) -#define ESPI_VW_IRQ_LEVEL_LOW(x) (0 << (x)) -#define ESPI_VW_IRQ_EDGE_HIGH(x) (1 << (x)) -#define ESPI_VW_IRQ_EDGE_LOW(x) (0 << (x)) +/* + * Internally the SoC uses active low signals for the IRQs. This means what when + * the eSPI controller comes out of reset, it's driving its IRQ lines high. + * In order to avoid any spurious interrupts the IO-APIC must be configured to + * trigger on active low signals. The PIC is only capable of triggering on + * active high signals so the hardware has an inverter that converts the signals + * before they feed into the PIC. + * + * +----------+ Active Low + * | | | +--------+ + * | IO-APIC <------+ | +-----+ LPC | + * | | | <---+---> | +--------+ + * +----------+ | | + * | +-----+ | +--------+ + * +---+ AND <---+-----+ eSPI | + * | +-----+ | +--------+ + * +----------+ | | + * | | +--v--+ | +--------+ + * | PIC <---+ NOT | +-----+ PIR | + * | | ^ +-----+ +--------+ + * +----------+ | + * | Active High + * + * The eSPI controller has an inverter that is applied to incoming Virtual Wire + * IRQ messages. This allows eSPI peripherals to use active high signaling. + * If the peripheral uses active low signaling like the SoC does internally, the + * inverter can be disabled. + * + * The polarity register has the following behavior: + * 0: Invert the incoming VW IRQ before outputting to the AND gates. + * 1: Do not invert the incoming VW IRQ, but route it directly to the AND + * gates. + */ +#define ESPI_VW_IRQ_LEVEL_HIGH(x) (0 << (x)) +#define ESPI_VW_IRQ_LEVEL_LOW(x) (1 << (x)) +#define ESPI_VW_IRQ_EDGE_HIGH(x) (0 << (x)) +#define ESPI_VW_IRQ_EDGE_LOW(x) (1 << (x)) enum espi_io_mode { ESPI_IO_MODE_SINGLE = ESPI_IO_MODE_VALUE(0), |