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Message-ID: <a96bb112-2361-1af1-7189-b7c5cbbdbf1e@gmail.com>
Date: Wed, 19 Apr 2017 17:32:31 +0200
From: Marek Vasut <marek.vasut@...il.com>
To: Andrey Smirnov <andrew.smirnov@...il.com>
Cc: linux-mtd@...ts.infradead.org, Chris Healy <cphealy@...il.com>,
David Woodhouse <dwmw2@...radead.org>,
Brian Norris <computersforpeace@...il.com>,
Boris Brezillon <boris.brezillon@...e-electrons.com>,
Richard Weinberger <richard@....at>,
Cyrille Pitchen <cyrille.pitchen@...el.com>,
linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 3/3] mtd: dataflash: Make use of "extened device
information"
On 04/19/2017 05:07 PM, Andrey Smirnov wrote:
> On Wed, Apr 19, 2017 at 1:47 AM, Marek Vasut <marek.vasut@...il.com> wrote:
>> On 04/19/2017 04:58 AM, Andrey Smirnov wrote:
>>> On Tue, Apr 18, 2017 at 11:31 AM, Marek Vasut <marek.vasut@...il.com> wrote:
>>>> On 04/18/2017 04:21 PM, Andrey Smirnov wrote:
>>>>> In anticipation of supporting chips that need it, extend the size of
>>>>> struct flash_info's 'jedec_id' field to make room 2 byte of extended
>>>>> device information as well as add code to fetch this data during
>>>>> jedec_probe().
>>>>>
>>>>> Cc: cphealy@...il.com
>>>>> Cc: David Woodhouse <dwmw2@...radead.org>
>>>>> Cc: Brian Norris <computersforpeace@...il.com>
>>>>> Cc: Boris Brezillon <boris.brezillon@...e-electrons.com>
>>>>> Cc: Marek Vasut <marek.vasut@...il.com>
>>>>> Cc: Richard Weinberger <richard@....at>
>>>>> Cc: Cyrille Pitchen <cyrille.pitchen@...el.com>
>>>>> Cc: linux-kernel@...r.kernel.org
>>>>> Signed-off-by: Andrey Smirnov <andrew.smirnov@...il.com>
>>>>> ---
>>>>>
>>>>> Changes since [v1]:
>>>>>
>>>>> - Formatting
>>>>>
>>>>> [v1] http://lkml.kernel.org/r/20170411161722.11164-1-andrew.smirnov@gmail.com
>>>>>
>>>>>
>>>>> drivers/mtd/devices/mtd_dataflash.c | 113 +++++++++++++++++++++---------------
>>>>> 1 file changed, 65 insertions(+), 48 deletions(-)
>>>>>
>>>>> diff --git a/drivers/mtd/devices/mtd_dataflash.c b/drivers/mtd/devices/mtd_dataflash.c
>>>>> index 5b7a8c3..5d694a4 100644
>>>>> --- a/drivers/mtd/devices/mtd_dataflash.c
>>>>> +++ b/drivers/mtd/devices/mtd_dataflash.c
>>>>> @@ -690,7 +690,7 @@ struct flash_info {
>>>>> /* JEDEC id has a high byte of zero plus three data bytes:
>>>>> * the manufacturer id, then a two byte device id.
>>>>> */
>>>>> - u32 jedec_id;
>>>>> + u64 jedec_id;
>>>>>
>>>>> /* The size listed here is what works with OP_ERASE_PAGE. */
>>>>> unsigned nr_pages;
>>>>> @@ -713,63 +713,34 @@ static struct flash_info dataflash_data[] = {
>>>>> * These newer chips also support 128-byte security registers (with
>>>>> * 64 bytes one-time-programmable) and software write-protection.
>>>>> */
>>>>> - { "AT45DB011B", 0x1f2200, 512, 264, 9, SUP_POW2PS},
>>>>> - { "at45db011d", 0x1f2200, 512, 256, 8, SUP_POW2PS | IS_POW2PS},
>>>>> + { "AT45DB011B", 0x1f22000000, 512, 264, 9, SUP_POW2PS},
>>>>> + { "at45db011d", 0x1f22000000, 512, 256, 8, SUP_POW2PS | IS_POW2PS},
>>>>>
>>>>> - { "AT45DB021B", 0x1f2300, 1024, 264, 9, SUP_POW2PS},
>>>>> - { "at45db021d", 0x1f2300, 1024, 256, 8, SUP_POW2PS | IS_POW2PS},
>>>>> + { "AT45DB021B", 0x1f23000000, 1024, 264, 9, SUP_POW2PS},
>>>>> + { "at45db021d", 0x1f23000000, 1024, 256, 8, SUP_POW2PS | IS_POW2PS},
>>>>>
>>>>> - { "AT45DB041x", 0x1f2400, 2048, 264, 9, SUP_POW2PS},
>>>>> - { "at45db041d", 0x1f2400, 2048, 256, 8, SUP_POW2PS | IS_POW2PS},
>>>>> + { "AT45DB041x", 0x1f24000000, 2048, 264, 9, SUP_POW2PS},
>>>>> + { "at45db041d", 0x1f24000000, 2048, 256, 8, SUP_POW2PS | IS_POW2PS},
>>>>>
>>>>> - { "AT45DB081B", 0x1f2500, 4096, 264, 9, SUP_POW2PS},
>>>>> - { "at45db081d", 0x1f2500, 4096, 256, 8, SUP_POW2PS | IS_POW2PS},
>>>>> + { "AT45DB081B", 0x1f25000000, 4096, 264, 9, SUP_POW2PS},
>>>>> + { "at45db081d", 0x1f25000000, 4096, 256, 8, SUP_POW2PS | IS_POW2PS},
>>>>>
>>>>> - { "AT45DB161x", 0x1f2600, 4096, 528, 10, SUP_POW2PS},
>>>>> - { "at45db161d", 0x1f2600, 4096, 512, 9, SUP_POW2PS | IS_POW2PS},
>>>>> + { "AT45DB161x", 0x1f26000000, 4096, 528, 10, SUP_POW2PS},
>>>>> + { "at45db161d", 0x1f26000000, 4096, 512, 9, SUP_POW2PS | IS_POW2PS},
>>>>>
>>>>> - { "AT45DB321x", 0x1f2700, 8192, 528, 10, 0}, /* rev C */
>>>>> + { "AT45DB321x", 0x1f27000000, 8192, 528, 10, 0}, /* rev C */
>>>>>
>>>>> - { "AT45DB321x", 0x1f2701, 8192, 528, 10, SUP_POW2PS},
>>>>> - { "at45db321d", 0x1f2701, 8192, 512, 9, SUP_POW2PS | IS_POW2PS},
>>>>> + { "AT45DB321x", 0x1f27010000, 8192, 528, 10, SUP_POW2PS},
>>>>> + { "at45db321d", 0x1f27010000, 8192, 512, 9, SUP_POW2PS | IS_POW2PS},
>>>>>
>>>>> - { "AT45DB642x", 0x1f2800, 8192, 1056, 11, SUP_POW2PS},
>>>>> - { "at45db642d", 0x1f2800, 8192, 1024, 10, SUP_POW2PS | IS_POW2PS},
>>>>> + { "AT45DB642x", 0x1f28000000, 8192, 1056, 11, SUP_POW2PS},
>>>>> + { "at45db642d", 0x1f28000000, 8192, 1024, 10, SUP_POW2PS | IS_POW2PS},
>>>>> };
>>>>>
>>>>> -static struct flash_info *jedec_probe(struct spi_device *spi)
>>>>> +static struct flash_info *jedec_lookup(struct spi_device *spi, u64 jedec)
>>>>> {
>>>>> - int ret, i;
>>>>> - u8 code = OP_READ_ID;
>>>>> - u8 id[3];
>>>>> - u32 jedec;
>>>>> + int status, i;
>>>>> struct flash_info *info;
>>>>> - int status;
>>>>> -
>>>>> - /*
>>>>> - * JEDEC also defines an optional "extended device information"
>>>>> - * string for after vendor-specific data, after the three bytes
>>>>> - * we use here. Supporting some chips might require using it.
>>>>> - *
>>>>> - * If the vendor ID isn't Atmel's (0x1f), assume this call failed.
>>>>> - * That's not an error; only rev C and newer chips handle it, and
>>>>> - * only Atmel sells these chips.
>>>>> - */
>>>>> - ret = spi_write_then_read(spi, &code, 1, id, 3);
>>>>> - if (ret < 0) {
>>>>> - pr_debug("%s: error %d reading JEDEC ID\n",
>>>>> - dev_name(&spi->dev), ret);
>>>>> - return ERR_PTR(ret);
>>>>> - }
>>>>> -
>>>>> - if (id[0] != CFI_MFR_ATMEL)
>>>>> - return NULL;
>>>>> -
>>>>> - jedec = id[0];
>>>>> - jedec = jedec << 8;
>>>>> - jedec |= id[1];
>>>>> - jedec = jedec << 8;
>>>>> - jedec |= id[2];
>>>>
>>>> Hm, the diff again screwed this up, oh well ...
>>>>
>>>>> for (i = 0, info = dataflash_data;
>>>>> i < ARRAY_SIZE(dataflash_data);
>>>>> @@ -799,12 +770,58 @@ static struct flash_info *jedec_probe(struct spi_device *spi)
>>>>> }
>>>>> }
>>>>>
>>>>> + return NULL;
>>>>> +}
>>>>> +
>>>>> +static struct flash_info *jedec_probe(struct spi_device *spi)
>>>>> +{
>>>>> + int ret;
>>>>> + u8 code = OP_READ_ID;
>>>>> + u8 id[8] = {0};
>>>>> + const unsigned int id_size = 5;
>>>>> + const unsigned int first_byte = sizeof(id) - id_size;
>>>>> + const u64 eid_mask = GENMASK_ULL(63, 16);
>>>>> + u64 jedec;
>>>>> + struct flash_info *info;
>>>>> +
>>>>> + /*
>>>>> + * JEDEC also defines an optional "extended device information"
>>>>> + * string for after vendor-specific data, after the three bytes
>>>>> + * we use here. Supporting some chips might require using it.
>>>>> + *
>>>>> + * If the vendor ID isn't Atmel's (0x1f), assume this call failed.
>>>>> + * That's not an error; only rev C and newer chips handle it, and
>>>>> + * only Atmel sells these chips.
>>>>> + */
>>>>> + ret = spi_write_then_read(spi, &code, 1, &id[first_byte], id_size);
>>>>> + if (ret < 0) {
>>>>> + pr_debug("%s: error %d reading JEDEC ID\n",
>>>>> + dev_name(&spi->dev), ret);
>>>>
>>>> I think you can turn this into:
>>>>
>>>> dev_err(&spi->dev, "error %d reading JEDEC ID\n", ret);
>>>
>>> OK, will do it in a separate patch, since this is original code.
>>
>> OK
>>
>>>>> + return ERR_PTR(ret);
>>>>> + }
>>>>> +
>>>>> + if (id[first_byte] != CFI_MFR_ATMEL)
>>>>> + return NULL;
>>>>> +
>>>>> + jedec = be64_to_cpup((__be64 *)id);
>>>>> +
>>>>> + info = jedec_lookup(spi, jedec);
>>>>> + if (info)
>>>>> + return info;
>>>>> +
>>>>> + /* Clear extended id bits and try to find a match again */
>>>>> + jedec &= eid_mask;
>>>>
>>>> Wouldn't that be jedec &= ~eid_mask; (with a tilde) if you want to clear
>>>> them ?
>>>
>>> eid_mask is generated as bits 63 to 16 with GENMASK_ULL, so bits 15 to
>>> 0 should already be zeroed out. I can rename it to eid_mask_inverted
>>> so it's less confusing.
>>
>> I think that's a good idea and you can make the mask u32 instead of u64.
>> But isn't eid_mask_inverted the same as id_mask ?
>
> I just realized that "eid_mask" is used only in one place and I don't
> gain anything by having that variable, so I think what I'd do is use
> GENMASK in-place, then it should be clear why there's no bit inversion
> and there's no dilemma on how to name the variable.
The upside of defining mask as a macro is that you can derive the
meaning of the macro from it's name . If you use ad-hoc constant in the
code, you cannot do that. And there might be spots in the code which
will re-use that macro in the future.
--
Best regards,
Marek Vasut
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