| Message ID | 1397064774-31784-4-git-send-email-computersforpeace@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
On Wednesday, April 09, 2014 at 07:32:49 PM, Brian Norris wrote: > Signed-off-by: Brian Norris <computersforpeace@gmail.com> > --- > WIP. This could be improved more (e.g., don't spend too much time > documenting history; just document the current framework) > > Documentation/mtd/spi-nor.txt | 27 +++++++++++++++------------ > 1 file changed, 15 insertions(+), 12 deletions(-) > > diff --git a/Documentation/mtd/spi-nor.txt b/Documentation/mtd/spi-nor.txt > index 294d5b06f892..bfcdeb94e053 100644 > --- a/Documentation/mtd/spi-nor.txt > +++ b/Documentation/mtd/spi-nor.txt > @@ -1,16 +1,20 @@ > SPI NOR framework > ============================================ > > -Part I - why we need this framework? > +Part I - Why do we need this framework? > ------------------------------------- The underline is not matching the length of the text now ;-) > > -The SPI bus controller only deals with the byte stream. > -Some controller does not works like a SPI bus controller, it works > -like a SPI NOR controller instead, such as the Freescale's QuadSPI > controller. +SPI bus controllers (drivers/spi/) only deal with streams of > bytes; the bus +controller operates agnostic of the specific device > attached. However, some +controllers (such as Freescale's QuadSPI > controller) cannot easily handle +arbitrary streams of bytes, but rather > are designed specifically for SPI NOR. You use the word 'specifically' here and below quick after one another, that doesn't sound nice when you read the text. > -The Freescale's QuadSPI controller should know the NOR commands to > -find the right LUT sequence. Unfortunately, the old code can not meet > -this requirement. > +Specifically, Freescale's QuadSPI controller must know the NOR commands to [...] Best regards, Marek Vasut
On Wed, Apr 09, 2014 at 07:44:15PM +0200, Marek Vasut wrote: > On Wednesday, April 09, 2014 at 07:32:49 PM, Brian Norris wrote: > > Signed-off-by: Brian Norris <computersforpeace@gmail.com> > > --- > > WIP. This could be improved more (e.g., don't spend too much time > > documenting history; just document the current framework) > > > > Documentation/mtd/spi-nor.txt | 27 +++++++++++++++------------ > > 1 file changed, 15 insertions(+), 12 deletions(-) > > > > diff --git a/Documentation/mtd/spi-nor.txt b/Documentation/mtd/spi-nor.txt > > index 294d5b06f892..bfcdeb94e053 100644 > > --- a/Documentation/mtd/spi-nor.txt > > +++ b/Documentation/mtd/spi-nor.txt > > @@ -1,16 +1,20 @@ > > SPI NOR framework > > ============================================ > > > > -Part I - why we need this framework? > > +Part I - Why do we need this framework? > > ------------------------------------- > > The underline is not matching the length of the text now ;-) It wasn't exactly matching in the first place. But I'll adjust all the headings so the line is exactly as long as the text. > > > > -The SPI bus controller only deals with the byte stream. > > -Some controller does not works like a SPI bus controller, it works > > -like a SPI NOR controller instead, such as the Freescale's QuadSPI > > controller. +SPI bus controllers (drivers/spi/) only deal with streams of > > bytes; the bus +controller operates agnostic of the specific device > > attached. However, some +controllers (such as Freescale's QuadSPI > > controller) cannot easily handle +arbitrary streams of bytes, but rather > > are designed specifically for SPI NOR. > > You use the word 'specifically' here and below quick after one another, that > doesn't sound nice when you read the text. Sure, thanks for pointing it out. > > -The Freescale's QuadSPI controller should know the NOR commands to > > -find the right LUT sequence. Unfortunately, the old code can not meet > > -this requirement. > > +Specifically, Freescale's QuadSPI controller must know the NOR commands to My changes are pushed here temporarily, and I'll send v2 in the next day or so: http://git.infradead.org/users/norris/linux-mtd.git/shortlog/refs/heads/spinor Brian
diff --git a/Documentation/mtd/spi-nor.txt b/Documentation/mtd/spi-nor.txt index 294d5b06f892..bfcdeb94e053 100644 --- a/Documentation/mtd/spi-nor.txt +++ b/Documentation/mtd/spi-nor.txt @@ -1,16 +1,20 @@ SPI NOR framework ============================================ -Part I - why we need this framework? +Part I - Why do we need this framework? ------------------------------------- -The SPI bus controller only deals with the byte stream. -Some controller does not works like a SPI bus controller, it works -like a SPI NOR controller instead, such as the Freescale's QuadSPI controller. +SPI bus controllers (drivers/spi/) only deal with streams of bytes; the bus +controller operates agnostic of the specific device attached. However, some +controllers (such as Freescale's QuadSPI controller) cannot easily handle +arbitrary streams of bytes, but rather are designed specifically for SPI NOR. -The Freescale's QuadSPI controller should know the NOR commands to -find the right LUT sequence. Unfortunately, the old code can not meet -this requirement. +Specifically, Freescale's QuadSPI controller must know the NOR commands to +find the right LUT sequence. Unfortunately, the SPI subsystem has no notion of +opcodes, addresses, or data payloads; a SPI controller simply knows to send or +receive bytes (Tx and Rx). Therefore, we must define a new layering scheme under +which the controller driver is aware of the opcodes, addressing, and other +details of the SPI NOR protocol. Part II - How does the framework work? ------------------------------------- @@ -40,7 +44,7 @@ m25p80 code anymore. ------------------------ SPI NOR chip - With the SPI NOR controller driver(Freescale QuadSPI), it looks like: + With the SPI NOR controller driver (Freescale QuadSPI), it looks like: MTD ------------------------ SPI NOR framework @@ -53,7 +57,6 @@ Part III - How can the drivers use the framework ------------------------------------- The main API is the spi_nor_scan(). Before you call the hook, you should -initialize the necessary fields for spi_nor{}. -Please see the drivers/mtd/spi-nor/spi-nor.c for detail. -Please also reference to the fsl-quadspi.c when you want to write a new driver -for a SPI NOR controller. +initialize the necessary fields for spi_nor{}. Please see the +drivers/mtd/spi-nor/spi-nor.c for detail. Please also refer to the fsl-quadspi.c +when you want to write a new driver for a SPI NOR controller.
Signed-off-by: Brian Norris <computersforpeace@gmail.com> --- WIP. This could be improved more (e.g., don't spend too much time documenting history; just document the current framework) Documentation/mtd/spi-nor.txt | 27 +++++++++++++++------------ 1 file changed, 15 insertions(+), 12 deletions(-)