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mtd: rawnand: sunxi: Add A23/A33 DMA support 

Allwinner NAND controllers can make use of DMA to enhance the I/O
throughput thanks to ECC pipelining. DMA handling with A23/A33 NAND IP
is a bit different than with the older SoCs, hence the introduction of
a new compatible to handle:
* the differences between register offsets,
* the burst length change from 4 to minimum 8,
* drive SRAM accesses through the AHB bus instead of the MBUS.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
This commit is contained in:
Miquel Raynal 2019-04-08 09:41:46 +02:00
parent a760e77d75
commit c49836f05a
1 changed files with 36 additions and 2 deletions
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38
drivers/mtd/nand/raw/sunxi_nand.c
View File

@ -43,6 +43,7 @@
#define NFC_REG_RCMD_SET 0x0028
#define NFC_REG_WCMD_SET 0x002C
#define NFC_REG_A10_IO_DATA 0x0030
#define NFC_REG_A23_IO_DATA 0x0300
#define NFC_REG_ECC_CTL 0x0034
#define NFC_REG_ECC_ST 0x0038
#define NFC_REG_DEBUG 0x003C
@ -204,10 +205,14 @@ static inline struct sunxi_nand_chip *to_sunxi_nand(struct nand_chip *nand)
* NAND Controller capabilities structure: stores NAND controller capabilities
* for distinction between compatible strings.
*
* @sram_through_ahb: On A23, we choose to access the internal RAM through AHB
* instead of MBUS (less configuration). A10, A10s, A13 and
* A20 use the MBUS but no extra configuration is needed.
* @reg_io_data: I/O data register
* @dma_maxburst: DMA maxburst
*/
struct sunxi_nfc_caps {
bool sram_through_ahb;
unsigned int reg_io_data;
unsigned int dma_maxburst;
};
@ -363,10 +368,29 @@ static int sunxi_nfc_dma_op_prepare(struct sunxi_nfc *nfc, const void *buf,
goto err_unmap_buf;
}
writel(readl(nfc->regs + NFC_REG_CTL) | NFC_RAM_METHOD,
nfc->regs + NFC_REG_CTL);
/*
* On A23, we suppose the "internal RAM" (p.12 of the NFC user manual)
* refers to the NAND controller's internal SRAM. This memory is mapped
* and so is accessible from the AHB. It seems that it can also be
* accessed by the MBUS. MBUS accesses are mandatory when using the
* internal DMA instead of the external DMA engine.
*
* During DMA I/O operation, either we access this memory from the AHB
* by clearing the NFC_RAM_METHOD bit, or we set the bit and use the
* MBUS. In this case, we should also configure the MBUS DMA length
* NFC_REG_MDMA_CNT(0xC4) to be chunksize * nchunks. NAND I/O over MBUS
* are also limited to 32kiB pages.
*/
if (nfc->caps->sram_through_ahb)
writel(readl(nfc->regs + NFC_REG_CTL) & ~NFC_RAM_METHOD,
nfc->regs + NFC_REG_CTL);
else
writel(readl(nfc->regs + NFC_REG_CTL) | NFC_RAM_METHOD,
nfc->regs + NFC_REG_CTL);
writel(nchunks, nfc->regs + NFC_REG_SECTOR_NUM);
writel(chunksize, nfc->regs + NFC_REG_CNT);
dmat = dmaengine_submit(dmad);
ret = dma_submit_error(dmat);
@ -2175,11 +2199,21 @@ static const struct sunxi_nfc_caps sunxi_nfc_a10_caps = {
.dma_maxburst = 4,
};
static const struct sunxi_nfc_caps sunxi_nfc_a23_caps = {
.sram_through_ahb = true,
.reg_io_data = NFC_REG_A23_IO_DATA,
.dma_maxburst = 8,
};
static const struct of_device_id sunxi_nfc_ids[] = {
{
.compatible = "allwinner,sun4i-a10-nand",
.data = &sunxi_nfc_a10_caps,
},
{
.compatible = "allwinner,sun8i-a23-nand-controller",
.data = &sunxi_nfc_a23_caps,
},
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, sunxi_nfc_ids);