From: <Tudor.Ambarus@microchip.com>
To: <michael@walle.cc>
Cc: <linux-mtd@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
<miquel.raynal@bootlin.com>, <richard@nod.at>, <vigneshr@ti.com>,
<boris.brezillon@collabora.com>
Subject: Re: [PATCH v6 4/5] mtd: spi-nor: atmel: Fix unlock_all() for AT25FS010/040
Date: Wed, 2 Dec 2020 10:32:04 +0000 [thread overview]
Message-ID: <33b3dd7d-3aa0-2cf2-6f0c-1afaa4dff61d@microchip.com> (raw)
In-Reply-To: <a8ce7d3a61d6f7bd988917291e938954@walle.cc>
On 11/30/20 4:16 PM, Michael Walle wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>
> Am 2020-11-28 09:25, schrieb Tudor.Ambarus@microchip.com:
>> On 11/26/20 10:26 PM, Michael Walle wrote:
>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know
>>> the content is safe
>>>
>>> These flashes have some weird BP bits mapping which aren't supported
>>> in
>>> the current locking code. Just add a simple unlock op to unprotect the
>>> entire flash array which is needed for legacy behavior.
>>>
>>> Signed-off-by: Michael Walle <michael@walle.cc>
>>> ---
>>> changes since v5
>>> - new patch
>>>
>>> drivers/mtd/spi-nor/atmel.c | 53
>>> +++++++++++++++++++++++++++++++++++--
>>> drivers/mtd/spi-nor/core.c | 2 +-
>>> drivers/mtd/spi-nor/core.h | 1 +
>>> 3 files changed, 53 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/mtd/spi-nor/atmel.c b/drivers/mtd/spi-nor/atmel.c
>>> index 49d392c6c8bc..fe6a4653823d 100644
>>> --- a/drivers/mtd/spi-nor/atmel.c
>>> +++ b/drivers/mtd/spi-nor/atmel.c
>>> @@ -8,10 +8,59 @@
>>>
>>> #include "core.h"
>>>
>>> +/*
>>> + * The Atmel AT25FS010/AT25FS040 parts have some weird configuration
>>> for the
>>> + * block protection bits. We don't support them. But legacy behaviour
>>> in linux
>>> + * is to unlock the whole flash array on startup. Therefore, we have
>>> to support
>>> + * exactly this operation.
>>> + */
>>> +static int atmel_at25fs_lock(struct spi_nor *nor, loff_t ofs,
>>> uint64_t len)
>>> +{
>>> + return -EOPNOTSUPP;
>>> +}
>>> +
>>> +static int atmel_at25fs_unlock(struct spi_nor *nor, loff_t ofs,
>>> uint64_t len)
>>> +{
>>> + /* We only support unlocking the whole flash array */
>>> + if (ofs || len != nor->params->size)
>>> + return -EINVAL;
>>> +
>>> + /*
>>> + * Write 0x00 to the status register to try to disable the
>>> write
>>> + * protection. This will fail if SRWD (the datasheet calls it
>>> WPEN) is
>>> + * set. But there is nothing we can do.
>>> + */
>>
>> can't we do the same as you did in 5/5?
>
> Sure, but - assuming it is only used for the legacy unlock all operation
> - the
> outcome will be the same. It will either keep being locked or all will
> be
> unlocked.
In case WP# is asserted, we'll catch this via the dev_dbg message in
spi_nor_write_sr_and_check() when trying to clear the SRWD bit. We will
have an idea of what's going on, instead of a silent fail to unlock.
>
> That being said, I can also change it to the same as the
> global_unprotect().
> I don't have any option on that other than this is simpler.
>
> -michael
next prev parent reply other threads:[~2020-12-02 10:33 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-26 20:26 [PATCH v6 0/5] mtd: spi-nor: keep lock bits if they are non-volatile Michael Walle
2020-11-26 20:26 ` [PATCH v6 1/5] mtd: spi-nor: atmel: remove global protection flag Michael Walle
2020-11-26 20:26 ` [PATCH v6 2/5] mtd: spi-nor: sst: " Michael Walle
2020-11-26 20:26 ` [PATCH v6 3/5] mtd: spi-nor: intel: " Michael Walle
2020-11-27 9:07 ` Tudor.Ambarus
2020-11-26 20:26 ` [PATCH v6 4/5] mtd: spi-nor: atmel: Fix unlock_all() for AT25FS010/040 Michael Walle
2020-11-28 8:25 ` Tudor.Ambarus
2020-11-30 14:16 ` Michael Walle
2020-12-02 10:32 ` Tudor.Ambarus [this message]
2020-11-26 20:26 ` [PATCH v6 5/5] mtd: spi-nor: keep lock bits if they are non-volatile Michael Walle
2020-11-28 10:17 ` Tudor.Ambarus
2020-11-30 14:38 ` Michael Walle
2020-12-02 11:10 ` Tudor.Ambarus
2020-12-02 11:25 ` Michael Walle
2020-12-02 14:09 ` Tudor.Ambarus
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