[U-Boot] [PATCH v4 1/3] dm: implement a MTD uclass

[Thomas Chou <thomas@wytron.com.tw>]

On 2015?11?03? 22:55, Jagan Teki wrote:
> On 3 November 2015 at 20:19, Thomas Chou <thomas@wytron.com.tw> wrote:
>> Hi Jagan,
>>
>> On 2015?11?03? 22:41, Jagan Teki wrote:
>>>
>>> Hi Thomas,
>>>
>>> On 3 November 2015 at 18:39, Thomas Chou <thomas@wytron.com.tw> wrote:
>>>>
>>>> Implement a Memory Technology Device (MTD) uclass. It should
>>>> include most flash drivers in the future. Though no uclass ops
>>>> are defined yet, the MTD ops could be used.
>>>>
>>>> The NAND flash driver is based on MTD. The CFI flash and SPI
>>>> flash support MTD, too. It should make sense to convert them
>>>> to MTD uclass.
>>>
>>>
>>> Why does MTD require driver model? Should drivers like nand, cfi or
>>> etc register mtd core should need to move on dm?
>>
>>
>> The driver model combined with device tree control of u-boot offers dynamic
>> binding of drivers and devices. It is expected that all drivers will be
>> converted to driver model, including nand, cfi and spi flash.
>
> So, mtd_info ops like _erase, _write and _read will also change or
> something like this
>
> struct dm_mtd_info {
>      struct mtd_info *info;
>      struct udevice *dev;
> };

Not exactly. I included udevice in mtd_info as it was device for Linux.

@@ -272,6 +273,8 @@ struct mtd_info {
  	struct module *owner;
  #ifndef __UBOOT__
  	struct device dev;
+#else
+	struct udevice *dev;
  #endif
  	int usecount;
  };

I think the mtd ops is more complete and widely used. There might be no 
need to reinvent the dm_mtd ops. The mtd uclass priv is set to mtd_info 
and we can get it with mtd_get_info(dev). Then call mtd ops, like 
mtd_read() mtd_write and mtd_erase(), directly.

 >  See for example, I have recently added MTD support to spi_flash [1] [2]
 >
 > [1] https://patchwork.ozlabs.org/patch/529397/
 > [2] https://patchwork.ozlabs.org/patch/529399/

It seems we are working toward the same direction. :)

Simon suggested that we can have an unified flash class (for all cfi, 
spi and nand flash) after the discussion between Bin Meng and I. So I 
dropped the earlier cfi-flash uclass, and found the mtd might be a 
better uclass. We see the same point, "MTD has proven core for flash 
operations".

The work on cfi-flash is not complete yet. It needs to reshape to use 
mtd ops like your earlier patches. But I have to work on others.

The spi-flash uclass should be merged into mtd uclass and use mtd ops. 
Maybe you will be interested and will help. Thanks in advance.

The nand flash is more ready. But need to convert to driver model.

Best regards,
Thomas