Hi, I have a (soft-IP, FPGA based, single-port) very simple SATA device (https://github.com/enjoy-digital/litesata) that provides me (r/w) access to a single physical SATA hard drive. I can access one sector at a time from bare-metal C code, using DMA and the following three MMIO register sets: - phy: u8 enable; // write 1 to bit 0 to enable phy // bits 1..7 reserved u8 status_ro ; // bit 0 = 1 if overall phy ready // bit 1 = 1 if phy tx ready // bit 2 = 1 if phy rx ready // bit 3 = 1 if phy ctrl ready - dma_writer: // write one 512-bit sector to disk u64 sector; // 48-bit disk sector number u64 base; // 64-bit dma base address (source buffer) u8 start; // write 1 to bit 0 to start DMA transfer u8 done_ro; // read 1 from bit 0 when transfer complete u8 error_ro; // read 1 from bit 0 if transfer failed - dma_reader: // read one 512-bit sector from disk u64 sector; // 48-bit disk sector number u64 base; // 64-bit dma base address (dest. buffer) u8 start; // write 1 to bit 0 to start DMA transfer u8 done_ro; // read 1 from bit 0 when transfer complete u8 error_ro; // read 1 from bit 0 if transfer failed For practice, I'm trying to write a low level SATA driver to access the hard drive from Linux using this device. I've tried studying existing drivers under `drivers/ata/*` to get an idea how to "connect" my device into the Linux SATA subsystem, and also tried studying the "libATA Developer’s Guide" at https://www.kernel.org/doc/html/v5.18-rc5/driver-api/libata.html It turns out there's a sizable "impedance mismatch" between my understanding of my device's simple register interface and most of the "production" devices for which existing drivers have been written in `drivers/ata/*`... I'm not even sure if I should be looking at `drivers/ata/ahci_*.c` or rather `drivers/ata/sata_*.c` :) I'd like some help finding an existing driver that's "closest" conceptually to the behavior of my device (outlined above), that I can use as a source of inspiration and as a starting point in learning about the linux SATA subsystem. Alternatively, is there some "guided tour to the Linux SATA subsystem" that's a bit less of a firehose than the "LibATA Developer's Guide"? Many thanks for any clues or pointers, --Gabriel _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
