Hi, On 3/2/21 4:39 PM, Michael Walle wrote: > This may sound like a contradiction but some SPI-NOR flashes really > support erasing their OTP region until it is finally locked. Having the > possibility to erase an OTP region might come in handy during > development. > > The ioctl argument follows the OTPLOCK style. > > Signed-off-by: Michael Walle <michael@xxxxxxxx> > --- > OTP support for SPI-NOR flashes may be merged soon: > https://lore.kernel.org/linux-mtd/20210216162807.13509-1-michael@xxxxxxxx/ > > Tudor suggested to add support for the OTP erase operation most SPI-NOR > flashes have: > https://lore.kernel.org/linux-mtd/d4f74b1b-fa1b-97ec-858c-d807fe1f9e57@xxxxxxxxxxxxx/ > > Therefore, this is an RFC to get some feedback on the MTD side, once this > is finished, I can post a patch for mtd-utils. Then we'll have a foundation > to add the support to SPI-NOR. > > drivers/mtd/mtdchar.c | 7 ++++++- > drivers/mtd/mtdcore.c | 12 ++++++++++++ > include/linux/mtd/mtd.h | 3 +++ > include/uapi/mtd/mtd-abi.h | 2 ++ > 4 files changed, 23 insertions(+), 1 deletion(-) > > diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c > index 323035d4f2d0..da423dd031ae 100644 > --- a/drivers/mtd/mtdchar.c > +++ b/drivers/mtd/mtdchar.c > @@ -661,6 +661,7 @@ static int mtdchar_ioctl(struct file *file, u_int cmd, u_long arg) > case OTPGETREGIONCOUNT: > case OTPGETREGIONINFO: > case OTPLOCK: > + case OTPERASE: This is not a Safe IOCTL. We are destroying OTP data. Need to check for write permission before allowing the ioctl right? > case ECCGETLAYOUT: > case ECCGETSTATS: > case MTDFILEMODE: > @@ -938,6 +939,7 @@ static int mtdchar_ioctl(struct file *file, u_int cmd, u_long arg) > } > > case OTPLOCK: > + case OTPERASE: > { > struct otp_info oinfo; > > @@ -945,7 +947,10 @@ static int mtdchar_ioctl(struct file *file, u_int cmd, u_long arg) > return -EINVAL; > if (copy_from_user(&oinfo, argp, sizeof(oinfo))) > return -EFAULT; > - ret = mtd_lock_user_prot_reg(mtd, oinfo.start, oinfo.length); > + if (cmd == OTPLOCK) > + ret = mtd_lock_user_prot_reg(mtd, oinfo.start, oinfo.length); > + else > + ret = mtd_erase_user_prot_reg(mtd, oinfo.start, oinfo.length); > break; > } > > diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c > index 2d6423d89a17..d844d718ef77 100644 > --- a/drivers/mtd/mtdcore.c > +++ b/drivers/mtd/mtdcore.c > @@ -1918,6 +1918,18 @@ int mtd_lock_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t len) > } > EXPORT_SYMBOL_GPL(mtd_lock_user_prot_reg); > > +int mtd_erase_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t len) > +{ > + struct mtd_info *master = mtd_get_master(mtd); > + > + if (!master->_erase_user_prot_reg) > + return -EOPNOTSUPP; > + if (!len) > + return 0; > + return master->_erase_user_prot_reg(master, from, len); > +} > +EXPORT_SYMBOL_GPL(mtd_erase_user_prot_reg); > + > /* Chip-supported device locking */ > int mtd_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len) > { > diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h > index 157357ec1441..734ad7a8c353 100644 > --- a/include/linux/mtd/mtd.h > +++ b/include/linux/mtd/mtd.h > @@ -336,6 +336,8 @@ struct mtd_info { > size_t len, size_t *retlen, u_char *buf); > int (*_lock_user_prot_reg) (struct mtd_info *mtd, loff_t from, > size_t len); > + int (*_erase_user_prot_reg) (struct mtd_info *mtd, loff_t from, > + size_t len); > int (*_writev) (struct mtd_info *mtd, const struct kvec *vecs, > unsigned long count, loff_t to, size_t *retlen); > void (*_sync) (struct mtd_info *mtd); > @@ -517,6 +519,7 @@ int mtd_read_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t len, > int mtd_write_user_prot_reg(struct mtd_info *mtd, loff_t to, size_t len, > size_t *retlen, u_char *buf); > int mtd_lock_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t len); > +int mtd_erase_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t len); > > int mtd_writev(struct mtd_info *mtd, const struct kvec *vecs, > unsigned long count, loff_t to, size_t *retlen); > diff --git a/include/uapi/mtd/mtd-abi.h b/include/uapi/mtd/mtd-abi.h > index 65b9db936557..242015f60d10 100644 > --- a/include/uapi/mtd/mtd-abi.h > +++ b/include/uapi/mtd/mtd-abi.h > @@ -205,6 +205,8 @@ struct otp_info { > * without OOB, e.g., NOR flash. > */ > #define MEMWRITE _IOWR('M', 24, struct mtd_write_req) > +/* Erase a given range of user data (must be in mode %MTD_FILE_MODE_OTP_USER) */ > +#define OTPERASE _IOR('M', 25, struct otp_info) > Hmm, shouldn't this be: #define OTPERASE _IOW('M', 25, struct otp_info) Userspace is writing struct otp_info to the driver. OTPLOCK should probably be _IOW() as well. > /* > * Obsolete legacy interface. Keep it in order not to break userspace > Regards Vignesh
