On Thu, Oct 6, 2016 at 10:27 AM, Jagan Teki <[email protected]> wrote: > On Thu, Oct 6, 2016 at 8:32 PM, George McCollister > <[email protected]> wrote: >> I'm looking into adding a sub-command to sf to protect status >> registers on Winbond SPI flash parts via the status register protect >> bits SRP0, SRP1. I propose the sub-command be named sr-protect. >> >> My use case is simple, I want to make the SPI flash read-only when the >> /WP pin is low. To do this I must do 'sf protect lock 0 $size' then >> set SRP0 to 1 and hold the /WP pin low. Although my use case doesn't >> require it, setting SRP1 to 1 allows either Power Supply Lock-Down or >> One Time Program (if supported by hardware) and I would probably add >> support for these as well. >> >> All of the current Winbond SPI NOR flash part datasheets that I've >> looked at show that the parts support the same locking implemented in >> stm_lock() even though SPI_FLASH_CFI_MFR_WINBOND is not in the list of >> vendors which use the function. I'll change this to make >> SPI_FLASH_CFI_MFR_WINBOND parts use stm_lock(), stm_unlock(), >> stm_is_locked(). > > Does stm_lock can't protect the Winbond? how different is in the > process of doing when compared to stm?
stm_lock() does work with the Winbond parts. The issue is that you can simply unlock from software (stm_unlock). To make it impossible to write to the flash from software you must use stm_lock() then use the status register protect bits to prevent an unlock. > >> >> spi_flash_protect() (which ultimately calls either stm_lock() or >> stm_unlock()) is not part of the driver model (dm_spi_flash_ops). >> Is there any issue with adding another function (let's call it >> spi_flash_sr_protect) that is not part of the driver model? > > Why spi_flash_sr_protect, why can't existing stm_lock? Explained above. > > thanks! > -- > Jagan Teki > Free Software Engineer | www.openedev.com > U-Boot, Linux | Upstream Maintainer > Hyderabad, India. _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
