zynq-rs/libboard_zynq/src/sdio/adma.rs

/// ADMA library
use core::mem::MaybeUninit;
use super::SDIO;
use libcortex_a9::cache;
use libregister::{
    register, register_bit,
    RegisterR, RegisterW, RegisterRW, VolatileCell,
};

#[repr(C, align(4))]
pub struct Adma2Desc32 {
    attribute: Desc32Attribute,
    length: VolatileCell<u16>,
    address: VolatileCell<u32>,
}

// Default::default() cannot be used as it is not a constant function...
static mut ADMA2_DESCR32_TABLE: MaybeUninit<[Adma2Desc32; 32]> = MaybeUninit::uninit();

#[allow(unused)]
const DESC_MAX_LENGTH: u32 = 65536;

register!(desc32_attribute, Desc32Attribute, VolatileCell, u16);
register_bit!(desc32_attribute, trans, 5);
register_bit!(desc32_attribute, int, 2);
register_bit!(desc32_attribute, end, 1);
register_bit!(desc32_attribute, valid, 0);

/// Initialize `ADMA2_DESCR32_TABLE` and setup `adma_system_address`
pub fn setup_adma2_descr32(sdio: &mut SDIO, blk_cnt: u32, buffer: &[u8]) {
    let descr_table = unsafe { &mut *ADMA2_DESCR32_TABLE.as_mut_ptr() };
    let blk_size = sdio
        .regs
        .block_size_block_count
        .read()
        .transfer_block_size() as u32;

    let total_desc_lines = if blk_size * blk_cnt < DESC_MAX_LENGTH {
        1
    } else {
        blk_size * blk_cnt / DESC_MAX_LENGTH
            + if (blk_size * blk_cnt) % DESC_MAX_LENGTH == 0 {
                0
            } else {
                1
            }
    } as usize;

    let ptr = buffer.as_ptr() as u32;
    for desc_num in 0..total_desc_lines {
        descr_table[desc_num].address.set(ptr + (desc_num as u32) * DESC_MAX_LENGTH);
        descr_table[desc_num].attribute.write(
            Desc32Attribute::zeroed()
                .trans(true)
                .valid(true)
        );
        // 0 is the max length (65536)
        descr_table[desc_num].length.set(0);
    }
    descr_table[total_desc_lines - 1].attribute.modify(|_, w| w.end(true));
    descr_table[total_desc_lines - 1].length.set(
        (blk_cnt * blk_size - ((total_desc_lines as u32) - 1) * DESC_MAX_LENGTH) as u16,
    );
    unsafe {
        sdio.regs
            .adma_system_address
            .write(descr_table.as_ptr() as u32);
    }
    cache::dcci_slice(descr_table);
}