On Thu, 2018-11-22 at 11:51 +0530, Jagan Teki wrote:
On Wed, Nov 21, 2018 at 5:16 PM Guochun Mao guochun.mao@mediatek.com wrote:
Hi Jagan,
On Wed, 2018-11-21 at 15:08 +0530, Jagan Teki wrote:
+static int mtk_qspi_tx_rx(struct mtk_qspi_priv *priv) +{
int len = 1 + priv->txlen + priv->rxlen;int i, ret, idx;if (len > MTK_QSPI_MAX_SHIFT)return -ERR_INVAL;writeb(len * 8, &priv->regs->cnt);/* start at PRGDATA5, go down to PRGDATA0 */idx = MTK_QSPI_MAX_RX_TX_SHIFT - 1;/* opcode */writeb(priv->op, &priv->regs->prgdata[idx]);idx--;/* program TX data */for (i = 0; i < priv->txlen; i++, idx--)writeb(priv->tx[i], &priv->regs->prgdata[idx]);/* clear out rest of TX registers */while (idx >= 0) {writeb(0, &priv->regs->prgdata[idx]);idx--;}ret = mtk_qspi_execute_cmd(priv, MTK_QSPI_PRG_CMD);What does this execute do?
It send command to flash, and latch data if need.
does it intiate the controller register based flash command or so?
No, it doesn't.
Do you have Linux driver on the controller?
Yes, it's drivers/mtd/spi-nor/mtk-quadspi.c
This sounds more specific to flash controller rather than spi driver. Can you try to write driver in mtd side itself, like Linux spi-nor. use UCLASS_SPI_FLASH
Sorry, I'm a little confused. There are many files(***qspi.c) those that used for accessing spi flash under folder drivers/spi/. However, there's no specific flash controller driver implemented under drives/mtd, only common spi_flash framework. It's different with kernel. It seems that we only need implement the spi control logic of spi-flash-controller(this part not based on flash, it only do data-xfer), and spi_flash framework will work well base on it. Isn't that the purpose of this architecture?
Understand your point, to be precise the driver may a fall in trouble after sometime, if there is an additional flash specific features will attach in future. ie reason few of flash controllers in drivers/spi were unable to move further to add their features. and ie also reason for your driver in Linux which resides in spi-nor.
You can directly write UCLASS_SPI_FLASH like sf_dataflash, I can help if any issues with probing setup etc.
Hi Jagan,
Could you reconsider this driver?
The code can match our needs for a considerable time, it's simple and doesn't disrupt current architecture.
If we switched to MTD_SPI_FLASH, there will inevitably be some duplicated codes. The current version of code adopts the sf/spi framework, it can guarantee compatibility and code reusability ratio.
If spi-mem or spi-nor was introduced to uboot in future, we can quickly implement new version code.
Thanks.
BR, Guochun