> -----Original Message----- > From: Leif Lindholm [mailto:[email protected]] > Sent: Tuesday, September 12, 2017 5:39 PM > To: Methavanitpong, Pipat/メタワニットポン ピパット > <[email protected]> > Cc: [email protected]; [email protected]; > [email protected]; [email protected] > Subject: Re: [PATCH edk2-platforms 13/14] Silicon/Socionext: add driver > for SPI NOR flash > > On Tue, Sep 12, 2017 at 01:41:34AM +0000, > [email protected] wrote: > > > -----Original Message----- > > > From: Leif Lindholm [mailto:[email protected]] > > > Sent: Tuesday, September 12, 2017 4:13 AM > > > To: Ard Biesheuvel <[email protected]> > > > Cc: [email protected]; Methavanitpong, Pipat/メタワニットポン ピ > パット > > > <[email protected]>; [email protected]; > > > [email protected] > > > Subject: Re: [PATCH edk2-platforms 13/14] Silicon/Socionext: add > > > driver for SPI NOR flash > > > > > > On Fri, Sep 08, 2017 at 07:23:14PM +0100, Ard Biesheuvel wrote: > > > > This imports the driver sources provided by Socionext for the > > > > FIP006 SPI NOR flash device found on Synquacer SoCs. It has been > > > > slightly tweaked to bring it up to date with the changes made on > > > > the EDK2 side since it was forked. > > > > > > > > Contributed-under: TianoCore Contribution Agreement 1.1 > > > > Signed-off-by: Ard Biesheuvel <[email protected]> > > > [Methavanitpong, Pipat/メタワニットポン ピパット] > > Hi Leif, > > > > 1. Hex magic > > > > There are 2 hex magic in this driver > > > > 1. FIP006 command sequencer decode command > > > > FIP006 in command sequencer mode detects accesses to its memory > region. > > An access to this region is translated into commands according to > > FIP006_REG_CS_RD and FIP006_REG_CS_WR for read and write > accordingly. > > > > A single access can be translated up to 8 1-byte commands, as the > > registers have 8 slots each. Each command is transmitted > consecutively > > starting from their base addresses. > > > > Each slot in the registers are decoded as > > > > 1. Immediate value - CSDC(imm, ..., ..., DEC=0) > > 2. Addr[7:0] - CSDC(0x00, ..., ..., DEC=1) > > 3. Addr[15:8] - CSDC(0x01, ..., ..., DEC=1) > > 4. Addr[23:16] - CSDC(0x02, ..., ..., DEC=1) > > 5. Addr[31:24] - CSDC(0x03, ..., ..., DEC=1) > > 6. HiZ for 1 byte - CSDC(0x04, ..., ..., DEC=1) > > 7. Upper 4-bit immediate value + 4-bit HiZ - CSDC((imm << 4) | > 0x05, ..., ..., DEC=1) > > 8. Command termination - CSDC(0x07, ..., ..., DEC=1) > > > > 2. Micron N25Q flash command > > > > In order to send a command to a flash device, FIP006's > FIP006_REG_CS_RD > > and FIP006_REG_CS_WR must be set properly. NorFlashSetHostCommand() > > sets these registers according to an instance's command definition > table. > > > > For example; NorFlashSetHostCommand (Instance, 0x13) corresponds to > a > > read access with 4-byte addressing read serial nor flash command > (0x13). > > The result FIP006_REG_CS_RD is the following: > > > > FIP006_REG_CS_RD[0] = CSDC(0x13, 0, 1-bit lane, DEC=0) > > FIP006_REG_CS_RD[1] = CSDC(0x03, 0, 1-bit lane, DEC=1) > > FIP006_REG_CS_RD[2] = CSDC(0x02, 0, 1-bit lane, DEC=1) > > FIP006_REG_CS_RD[3] = CSDC(0x01, 0, 1-bit lane, DEC=1) > > FIP006_REG_CS_RD[4] = CSDC(0x00, 0, 1-bit lane, DEC=1) > > FIP006_REG_CS_RD[5] = CSDC(0x07, 0, 1-bit lane, DEC=1) > > FIP006_REG_CS_RD[6] = CSDC(0x07, 0, 1-bit lane, DEC=1) > > FIP006_REG_CS_RD[7] = CSDC(0x07, 0, 1-bit lane, DEC=1) > > Thank you for the explanation. > However, the code needs to be be readable by someone who does not have the > instruction set for each given component fresh in their mind. > > That means that direct numeral expressions should be avoided wherever they > are not mathematically obvious (and where you consider them obvious, > consider whether everyone else would agree without already knowing what > the code is intended to do). > > They should be replaced by #defines or enums as appropriate. > > > 2. Bit field declaration > > > > About the bitfield struct you mentioned in "Fip006Reg.h", What should > > be a good way to declare it? > > The problem with bitfields is that they are not very well defined in the C > language, and hence do not tend to be very portable. > > Tedious as it may seem, #defines with shifts and masks are usually the way > to go.
Thank you for your comment, Leif. I will see what I can do with Ard. > > Regards, > > Leif -- Pipat Methavanitpong Software Developer, S-Project 3 Socionext Inc. _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
