Intel 8254x: Difference between revisions
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When using MMIO, reading/writing to/from registers is very straight-forward. |
When using MMIO, reading/writing to/from registers is very straight-forward. |
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< |
<syntaxhighlight lang="c"> |
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*(uint32_t *)(ioaddr + reg) = val; // writes "val" to an MMIO address |
*(uint32_t *)(ioaddr + reg) = val; // writes "val" to an MMIO address |
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val = *(uint32_t *)(ioaddr + reg); // reads "val" from an MMIO address |
val = *(uint32_t *)(ioaddr + reg); // reads "val" from an MMIO address |
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</syntaxhighlight> |
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</source> |
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When using IO, reading/writing to/from registers is a little more complicated as the IO address space for the 8254x is only 8 bytes wide. |
When using IO, reading/writing to/from registers is a little more complicated as the IO address space for the 8254x is only 8 bytes wide. |
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IOADDR holds the IO address that the IODATA window operates on. So, basic operation is to set the IOADDR window and then the desired action using the IODATA window. |
IOADDR holds the IO address that the IODATA window operates on. So, basic operation is to set the IOADDR window and then the desired action using the IODATA window. |
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< |
<syntaxhighlight lang="c"> |
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outl(ioaddr + 0x00, reg); // set the IOADDR window |
outl(ioaddr + 0x00, reg); // set the IOADDR window |
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outl(ioaddr + 0x04, val); // write the value to the IOADDR window which will end up in the register in IOADDR |
outl(ioaddr + 0x04, val); // write the value to the IOADDR window which will end up in the register in IOADDR |
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inl(ioaddr + 0x04); // read back the value |
inl(ioaddr + 0x04); // read back the value |
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</syntaxhighlight> |
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</source> |
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== Initialization == |
== Initialization == |
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Obtaining the MAC is quite trivial and only requires reading the first 3-words of the EEPROM. |
Obtaining the MAC is quite trivial and only requires reading the first 3-words of the EEPROM. |
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< |
<syntaxhighlight lang="c"> |
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uint8_t dev_info.mac_addr[6]; |
uint8_t dev_info.mac_addr[6]; |
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*((uint16_t *)&dev_info.mac_addr[4]) = i8254x_read_eeprom(0x02); |
*((uint16_t *)&dev_info.mac_addr[4]) = i8254x_read_eeprom(0x02); |
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i8254x_unlock_eeprom(); |
i8254x_unlock_eeprom(); |
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</syntaxhighlight> |
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</source> |
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== Emulation == |
== Emulation == |
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