[PATCH 3/5] i2c: rzg2l: Add I2C driver for RZ/G2L family

[Paul Barker]

On 02/12/2023 18:18, Marek Vasut wrote:
> On 11/19/23 21:48, Paul Barker wrote:
>> On Sun, Nov 19, 2023 at 09:15:36PM +0100, Marek Vasut wrote:
>>> On 11/15/23 18:40, Paul Barker wrote:
>>>> This driver supports the I2C module on the Renesas RZ/G2L (R9A07G044)
>>>> SoC, also known as the RIIC module.
>>>>
>>>> This patch is based on both the u-boot driver in the Renesas RZ BSP
>>>> 3.0.5 release [1] (commit 7fcc1fdc2534), and the Linux v6.6 driver
>>>> (commit ffc253263a13).
>>>>
>>>> Support for deblocking the I2C bus is included as this may be needed
>>>> after triggering a reset via the Power Management IC (PMIC) over I2C
>>>> (the PMIC asserts the reset line before the SoC completes the I2C write
>>>> transaction with obvious bus locking effects). If the SDA line is
>>>> observed to be low during initialisation, we automatically attempt to
>>>> deblock.
>>>>
>>>> [1]: https://github.com/renesas-rz/renesas-u-boot-cip
>>>>
>>>> Signed-off-by: Paul Barker <paul.barker.ct at bp.renesas.com>
>>>
>>> The driver seems very similar to drivers/i2c/rcar_iic.c , can there be some
>>> code reuse ?
>>
>> My initial idea was to extend the R-Car iic driver but I quickly saw
>> that would be very messy. All the registers and bits are in different
>> places, the calculations are different (particularly in regard to
>> setting bus speed) and the read/write process has more edge cases for
>> the RZ/G2L. The bus recovery mechanism we use also doesn't exist on
>> previous R-Car SoCs.
>>
>> The Linux drivers for these modules are also separate, see
>> drivers/i2c/busses/i2c-sh_mobile.c (for R-Car and earlier SoCs) and
>> drivers/i2c/busses/i2c-riic.c (for RZ/G2L) in the Linux kernel.
> 
> Ah, I thought some of the registers were the same, but indeed the RZG 
> core is much more extensive.
> 
> You should either use devm_clk_*() in probe() or implement .remove 
> callback. With that fixed:
> 
> Reviewed-by: Marek Vasut <marek.vasut+renesas at mailbox.org>
> 
> And sorry for the delayed reply.

Here's an even more delayed reply from me! I've been busy on other work
but getting back to u-boot now.

Using devm_clk_get() in the probe function for this driver doesn't seem
to be needed. The `struct clk` is stored in a `struct riic_priv`, this
is allocated and freed automatically for each device as we set
`priv_auto` in the driver definition.

Thanks,

-- 
Paul Barker
-------------- next part --------------
A non-text attachment was scrubbed...
Name: OpenPGP_0x27F4B3459F002257.asc
Type: application/pgp-keys
Size: 3520 bytes
Desc: OpenPGP public key
URL: <https://lists.denx.de/pipermail/u-boot/attachments/20240220/b5ce497a/attachment.key>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: OpenPGP_signature.asc
Type: application/pgp-signature
Size: 236 bytes
Desc: OpenPGP digital signature
URL: <https://lists.denx.de/pipermail/u-boot/attachments/20240220/b5ce497a/attachment.sig>