linux-kernel - Re: [PATCH 2/2] mmc: dw_mmc-pltfm: socfpga: add method to configure clk-phase

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Date:   Tue, 20 Sep 2022 08:24:39 -0500
From:   Dinh Nguyen <dinguyen@...nel.org>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     jh80.chung@...sung.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, linux-mmc@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 2/2] mmc: dw_mmc-pltfm: socfpga: add method to configure
 clk-phase


Hi Ulf,

Thanks for the review!

On 9/20/22 07:17, Ulf Hansson wrote:
> On Mon, 19 Sept 2022 at 20:13, Dinh Nguyen <dinguyen@...nel.org> wrote:
>>
>> The clock-phase settings for the SDMMC controller in the SoCFPGA
>> Strarix10/Agilex/N5X platforms reside in a register in the System
>> Manager. Add a method to access that register through the syscon
>> interface.
>>
>> Signed-off-by: Dinh Nguyen <dinguyen@...nel.org>
>> ---
>>   drivers/mmc/host/dw_mmc-pltfm.c | 68 ++++++++++++++++++++++++++++++++-
>>   1 file changed, 67 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/host/dw_mmc-pltfm.c b/drivers/mmc/host/dw_mmc-pltfm.c
>> index 9901208be797..9e3237c18a9d 100644
>> --- a/drivers/mmc/host/dw_mmc-pltfm.c
>> +++ b/drivers/mmc/host/dw_mmc-pltfm.c
>> @@ -17,10 +17,15 @@
>>   #include <linux/mmc/host.h>
>>   #include <linux/mmc/mmc.h>
>>   #include <linux/of.h>
>> +#include <linux/mfd/altera-sysmgr.h>
>> +#include <linux/regmap.h>
>>
>>   #include "dw_mmc.h"
>>   #include "dw_mmc-pltfm.h"
>>
>> +#define SYSMGR_SDMMC_CTRL_SET(smplsel, drvsel) \
>> +       ((((smplsel) & 0x7) << 4) | (((drvsel) & 0x7) << 0))
>> +
>>   int dw_mci_pltfm_register(struct platform_device *pdev,
>>                            const struct dw_mci_drv_data *drv_data)
>>   {
>> @@ -62,9 +67,70 @@ const struct dev_pm_ops dw_mci_pltfm_pmops = {
>>   };
>>   EXPORT_SYMBOL_GPL(dw_mci_pltfm_pmops);
>>
>> +static int dw_mci_socfpga_priv_init(struct dw_mci *host)
>> +{
>> +       struct device_node *np = host->dev->of_node;
>> +       struct regmap *sys_mgr_base_addr;
>> +       u32 clk_phase[2] = {0}, reg_offset;
>> +       int i, rc, hs_timing;
>> +
>> +       rc = of_property_read_variable_u32_array(np, "clk-phase-sd-hs", &clk_phase[0], 2, 0);
> 
> This needs to be documented through updated DT bindings.

Ok, but it looks like clk-phase-sd-hs is already documented in 
Documentation/devicetree/bindings/mmc/mmc-controller.yaml

Should I create a specific documentation just for
"altr,socfpga-dw-mshc" and document "clk-phase-sd-hs"?

> 
>> +       if (rc) {
>> +               sys_mgr_base_addr =
>> +                       altr_sysmgr_regmap_lookup_by_phandle(np, "altr,sysmgr-syscon");
> 
> DT bindings?

"altr,sysmgr-syscon" has already been documented in
Documentation/devicetree/bindings/net/socfpga-dwmac.txt

>> +               if (IS_ERR(sys_mgr_base_addr)) {
>> +                       pr_err("%s: failed to find altr,sys-mgr regmap!\n", __func__);
>> +                       return 1;
>> +               }
>> +       } else
>> +               return 1;
>> +
>> +       of_property_read_u32_index(np, "altr,sysmgr-syscon", 1, &reg_offset);
> 
> DT bindings?

Same...

> 
>> +
>> +       for (i = 0; i < ARRAY_SIZE(clk_phase); i++) {
>> +               switch (clk_phase[i]) {
>> +               case 0:
>> +                       clk_phase[i] = 0;
>> +                       break;
>> +               case 45:
>> +                       clk_phase[i] = 1;
>> +                       break;
>> +               case 90:
>> +                       clk_phase[i] = 2;
>> +                       break;
>> +               case 135:
>> +                       clk_phase[i] = 3;
>> +                       break;
>> +               case 180:
>> +                       clk_phase[i] = 4;
>> +                       break;
>> +               case 225:
>> +                       clk_phase[i] = 5;
>> +                       break;
>> +               case 270:
>> +                       clk_phase[i] = 6;
>> +                       break;
>> +               case 315:
>> +                       clk_phase[i] = 7;
>> +                       break;
>> +               default:
>> +                       clk_phase[i] = 0;
>> +                       break;
>> +               }
>> +       }
> 
> In my opinion, it looks like converting to use
> mmc_of_parse_clk_phase() should be able to avoid some of the open
> coding above.
> 
> If you need some inspiration of how to implement this, you may have a
> look at drivers/mmc/host/sdhci-of-aspeed.c
> 

Got it.

>> +       hs_timing = SYSMGR_SDMMC_CTRL_SET(clk_phase[0], clk_phase[1]);
>> +       regmap_write(sys_mgr_base_addr, reg_offset, hs_timing);
>> +
>> +       return 0;
>> +}
>> +
>> +static const struct dw_mci_drv_data socfpga_drv_data = {
>> +       .init           = dw_mci_socfpga_priv_init,
>> +};
>> +
>>   static const struct of_device_id dw_mci_pltfm_match[] = {
>>          { .compatible = "snps,dw-mshc", },
>> -       { .compatible = "altr,socfpga-dw-mshc", },
>> +       { .compatible = "altr,socfpga-dw-mshc", .data = &socfpga_drv_data, },
>>          { .compatible = "img,pistachio-dw-mshc", },
>>          {},
>>   };
>> --
>> 2.25.1
>>
> 
> Kind regards
> Uffe

Dinh