linux-kernel - Re: [PATCH v8 1/2] spi: Add Renesas R-Car Gen3 RPC-IF SPI controller driver

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Date:   Fri, 8 Mar 2019 20:32:31 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Mason Yang <masonccyang@...c.com.tw>,
        Mark Brown <broonie@...nel.org>,
        Marek Vasut <marek.vasut@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-spi <linux-spi@...r.kernel.org>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        juliensu@...c.com.tw, Simon Horman <horms@...ge.net.au>,
        zhengxunli@...c.com.tw
Subject: Re: [PATCH v8 1/2] spi: Add Renesas R-Car Gen3 RPC-IF SPI controller
 driver

Hello!

On 03/08/2019 12:14 PM, Geert Uytterhoeven wrote:

>>> Add a driver for Renesas R-Car Gen3 RPC-IF SPI controller.
>>>
>>> Signed-off-by: Mason Yang <masonccyang@...c.com.tw>
>>> Signed-off-by: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
>> [...]
>>> diff --git a/drivers/spi/spi-renesas-rpc.c b/drivers/spi/spi-renesas-rpc.c
>>> new file mode 100644
>>> index 0000000..ea12017
>>> --- /dev/null
>>> +++ b/drivers/spi/spi-renesas-rpc.c
>>> @@ -0,0 +1,804 @@
>> [...]
>>> +static void rpc_spi_hw_init(struct rpc_spi *rpc)
>>> +{
>>> +     //
>>> +     // NOTE: The 0x260 are undocumented bits, but they must be set.
>>> +     //      RPC_PHYCNT_STRTIM is strobe timing adjustment bit,
>>> +     //      0x0 : the delay is biggest,
>>> +     //      0x1 : the delay is 2nd biggest,
>>> +     //      On H3 ES1.x, the value should be 0, while on others,
>>> +     //      the value should be 6.
>>> +     //
>>> +     regmap_write(rpc->regmap, RPC_PHYCNT, RPC_PHYCNT_CAL |
>>> +                               RPC_PHYCNT_STRTIM(6) | 0x260);
>>> +
>>> +     //
>>> +     // NOTE: The 0x1511144 are undocumented bits, but they must be set
>>> +     //       for RPC_PHYOFFSET1.
>>> +     //       The 0x31 are undocumented bits, but they must be set
>>> +     //       for RPC_PHYOFFSET2.
>>> +     //
>>> +     regmap_write(rpc->regmap, RPC_PHYOFFSET1, RPC_PHYOFFSET1_DDRTMG(3) |
>>> +                  0x1511144);
>>> +     regmap_write(rpc->regmap, RPC_PHYOFFSET2, 0x31 |
>>> +                  RPC_PHYOFFSET2_OCTTMG(4));
>>> +     regmap_write(rpc->regmap, RPC_SSLDR, RPC_SSLDR_SPNDL(7) |
>>> +                  RPC_SSLDR_SLNDL(7) | RPC_SSLDR_SCKDL(7));
>>> +     regmap_write(rpc->regmap, RPC_CMNCR, RPC_CMNCR_MD | RPC_CMNCR_SFDE |
>>> +                  RPC_CMNCR_MOIIO_HIZ | RPC_CMNCR_IOFV_HIZ |
>>> +                  RPC_CMNCR_BSZ(0));
>>> +}
>>
>>    We clearly need runtime PM get/put() calls around this code. Otherwise,
>> we're dependant on U-Boot leaving the clocks enabled...
> 
> Even that would be futile, as the common clock framework disables all
> unused clocks at late boot time.

   This code is executed during the probing time and it indeed works. The clocks seem
to be disabled somewhat later...

> Gr{oetje,eeting}s,
> 
>                         Geert

MBR, Sergei