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Subject: Re: [PATCH v2 1/3] soc: samsung: exynos-chipid: Pass revision reg
 offsets
To:     Sam Protsenko <semen.protsenko@linaro.org>
Cc:     Rob Herring <robh+dt@kernel.org>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        Linux Samsung SOC <linux-samsung-soc@vger.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
        devicetree <devicetree@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
References: <20211013202110.31701-1-semen.protsenko@linaro.org>
 <1cd31098-ba9d-f2e3-e34c-5bada00a2696@canonical.com>
 <CAPLW+4mtSnt8dCCtSeu-yNTR0F5ZO-hdjFjyGChi=tTWQQt85Q@mail.gmail.com>
From:   Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Message-ID: <dd61666c-fd1a-c152-9423-9dc6718b1626@canonical.com>
Date:   Thu, 14 Oct 2021 13:48:45 +0200
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On 14/10/2021 13:34, Sam Protsenko wrote:
> On Thu, 14 Oct 2021 at 10:11, Krzysztof Kozlowski
> <krzysztof.kozlowski@canonical.com> wrote:
>>
>> On 13/10/2021 22:21, Sam Protsenko wrote:
>>> Old Exynos SoCs have both Product ID and Revision ID in one single
>>> register, while new SoCs tend to have two separate registers for those
>>> IDs. Implement handling of both cases by passing Revision ID register
>>> offsets in driver data.
>>>
>>> Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
>>> ---
>>>  drivers/soc/samsung/exynos-chipid.c       | 67 +++++++++++++++++++----
>>>  include/linux/soc/samsung/exynos-chipid.h |  6 +-
>>>  2 files changed, 58 insertions(+), 15 deletions(-)
>>>
>>> diff --git a/drivers/soc/samsung/exynos-chipid.c b/drivers/soc/samsung/exynos-chipid.c
>>> index 5c1d0f97f766..7837331fb753 100644
>>> --- a/drivers/soc/samsung/exynos-chipid.c
>>> +++ b/drivers/soc/samsung/exynos-chipid.c
>>> @@ -16,6 +16,7 @@
>>>  #include <linux/errno.h>
>>>  #include <linux/mfd/syscon.h>
>>>  #include <linux/of.h>
>>> +#include <linux/of_device.h>
>>>  #include <linux/platform_device.h>
>>>  #include <linux/regmap.h>
>>>  #include <linux/slab.h>
>>> @@ -24,6 +25,17 @@
>>>
>>>  #include "exynos-asv.h"
>>>
>>> +struct exynos_chipid_variant {
>>> +     unsigned int rev_reg;           /* revision register offset */
>>> +     unsigned int main_rev_shift;    /* main revision offset in rev_reg */
>>> +     unsigned int sub_rev_shift;     /* sub revision offset in rev_reg */
>>> +};
>>> +
>>> +struct exynos_chipid_info {
>>> +     u32 product_id;
>>> +     u32 revision;
>>> +};
>>> +
>>>  static const struct exynos_soc_id {
>>>       const char *name;
>>>       unsigned int id;
>>> @@ -49,31 +61,55 @@ static const char *product_id_to_soc_id(unsigned int product_id)
>>>       int i;
>>>
>>>       for (i = 0; i < ARRAY_SIZE(soc_ids); i++)
>>> -             if ((product_id & EXYNOS_MASK) == soc_ids[i].id)
>>> +             if (product_id == soc_ids[i].id)
>>>                       return soc_ids[i].name;
>>>       return NULL;
>>>  }
>>>
>>> +static int exynos_chipid_get_chipid_info(struct regmap *regmap,
>>> +             const struct exynos_chipid_variant *data,
>>> +             struct exynos_chipid_info *soc_info)
>>> +{
>>> +     int ret;
>>> +     unsigned int val, main_rev, sub_rev;
>>> +
>>> +     ret = regmap_read(regmap, EXYNOS_CHIPID_REG_PRO_ID, &val);
>>> +     if (ret < 0)
>>> +             return ret;
>>> +     soc_info->product_id = val & EXYNOS_MASK;
>>> +
>>> +     ret = regmap_read(regmap, data->rev_reg, &val);
>>
>> Isn't this the same register as EXYNOS_CHIPID_REG_PRO_ID?
>>
> 
> It is for Exynos4210, but it's not for Exynos850 (see PATCH 3/3), as
> it's described in the commit message. I tried to keep this code
> unified for all SoCs.

Yeah, but for Exynos4210 you read the same register twice. It's
confusing. Read only once. You could compare the offsets and skip second
read.

> 
>>> +     if (ret < 0)
>>> +             return ret;
>>> +     main_rev = (val >> data->main_rev_shift) & EXYNOS_REV_PART_MASK;
>>> +     sub_rev = (val >> data->sub_rev_shift) & EXYNOS_REV_PART_MASK;
>>> +     soc_info->revision = (main_rev << EXYNOS_REV_PART_SHIFT) | sub_rev;
>>> +
>>> +     return 0;
>>> +}
>>> +
>>>  static int exynos_chipid_probe(struct platform_device *pdev)
>>>  {
>>> +     const struct exynos_chipid_variant *drv_data;
>>> +     struct exynos_chipid_info soc_info;
>>>       struct soc_device_attribute *soc_dev_attr;
>>>       struct soc_device *soc_dev;
>>>       struct device_node *root;
>>>       struct regmap *regmap;
>>> -     u32 product_id;
>>> -     u32 revision;
>>>       int ret;
>>>
>>> +     drv_data = of_device_get_match_data(&pdev->dev);
>>> +     if (!drv_data)
>>> +             return -EINVAL;
>>> +
>>>       regmap = device_node_to_regmap(pdev->dev.of_node);
>>>       if (IS_ERR(regmap))
>>>               return PTR_ERR(regmap);
>>>
>>> -     ret = regmap_read(regmap, EXYNOS_CHIPID_REG_PRO_ID, &product_id);
>>> +     ret = exynos_chipid_get_chipid_info(regmap, drv_data, &soc_info);
>>>       if (ret < 0)
>>>               return ret;
>>>
>>> -     revision = product_id & EXYNOS_REV_MASK;
>>> -
>>>       soc_dev_attr = devm_kzalloc(&pdev->dev, sizeof(*soc_dev_attr),
>>>                                   GFP_KERNEL);
>>>       if (!soc_dev_attr)
>>> @@ -86,8 +122,8 @@ static int exynos_chipid_probe(struct platform_device *pdev)
>>>       of_node_put(root);
>>>
>>>       soc_dev_attr->revision = devm_kasprintf(&pdev->dev, GFP_KERNEL,
>>> -                                             "%x", revision);
>>> -     soc_dev_attr->soc_id = product_id_to_soc_id(product_id);
>>> +                                             "%x", soc_info.revision);
>>> +     soc_dev_attr->soc_id = product_id_to_soc_id(soc_info.product_id);
>>>       if (!soc_dev_attr->soc_id) {
>>>               pr_err("Unknown SoC\n");
>>>               return -ENODEV;
>>> @@ -106,7 +142,7 @@ static int exynos_chipid_probe(struct platform_device *pdev)
>>>
>>>       dev_info(soc_device_to_device(soc_dev),
>>>                "Exynos: CPU[%s] PRO_ID[0x%x] REV[0x%x] Detected\n",
>>> -              soc_dev_attr->soc_id, product_id, revision);
>>> +              soc_dev_attr->soc_id, soc_info.product_id, soc_info.revision);
>>>
>>>       return 0;
>>>
>>> @@ -125,9 +161,18 @@ static int exynos_chipid_remove(struct platform_device *pdev)
>>>       return 0;
>>>  }
>>>
>>> +static const struct exynos_chipid_variant exynos4210_chipid_drv_data = {
>>> +     .rev_reg        = 0x0,
>>> +     .main_rev_shift = 0,
>>> +     .sub_rev_shift  = 4,
>>
>> The code does not look correct here. Subrev is at 0:3 bits, mainrev is
>> at 4:7.
>>
> 
> Right. I was confused by those existing macros:
> 
>     #define EXYNOS_SUBREV_MASK        (0xf << 4)
>     #define EXYNOS_MAINREV_MASK        (0xf << 0)
> 
> Those were probably wrong the whole time? Anyway, now I've found
> Exynos4412 User Manual and checked it there -- you are right about
> offsets. Will fix in v3.

They were not used, I think.

> 
>> Did you test it that it produces same result? Looks not - I gave it a
>> try and got wrong revision.
>>
> 
> I only have Exynos850 based board, and that has 0x0 in Revision ID
> register. But for v3 I'll try to emulate register value in the code
> and make sure that the read value does not change with patch applied.

You should get one of Odroid boards to test it. The MC1 is fairly cheap.

Best regards,
Krzysztof