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In /boot/device.hints: hint.ppc.0.at="isa" hint.ppc.0.irq="7"
For one or more PPBUS busses: device ppbus
During the probe phase, ppc detects parallel port chipsets and initializes private data according to their operating mode: COMPATIBLE, NIBBLE, PS/2, EPP, ECP and other mixed modes. If a mode is provided at startup through the flags variable of the boot interface, the operating mode of the chipset is forced according to flags and the hardware supported modes.
During the attach phase, ppc allocates a ppbus structure, initializes it and calls the ppbus attach function.
bits 0-3: chipset forced mode(s)
PPB_COMPATIBLE 0x0 /* Centronics compatible mode */ PPB_NIBBLE 0x1 /* reverse 4 bit mode */ PPB_PS2 0x2 /* PS/2 byte mode */ PPB_EPP 0x4 /* EPP mode, 32 bit */ PPB_ECP 0x8 /* ECP mode */ And any mixed values. | |
bit 4: EPP protocol (0 EPP 1.9, 1 EPP 1.7) | |
bit 5: activate IRQ (1 IRQ disabled, 0 IRQ enabled) | |
bit 6: disable chipset specific detection | |
bit 7: disable FIFO detection | |
Your ppc_mychipset_detect() function should ensure that if the mode field of the flags boot variable is not null, then the operating mode is forced to the given mode and no other mode is available and ppb->ppb_avm field contains the available modes of the chipset.
PPC (4) | March 5, 1998 |
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