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SubjectRe: Adding a .platform_init callback to sdhci_arasan_ops
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On 28/11/16 12:44, Adrian Hunter wrote:
> On 28/11/16 13:20, Sebastian Frias wrote:
>> Hi Adrian,
>>
>> On 28/11/16 11:30, Adrian Hunter wrote:
>>> On 28/11/16 09:32, Michal Simek wrote:
>>>> +Sai for Xilinx perspective.
>>>>
>>>> On 25.11.2016 16:24, Sebastian Frias wrote:
>>>>> Hi,
>>>>>
>>>>> When using the Arasan SDHCI HW IP, there is a set of parameters called
>>>>> "Hardware initialized registers"
>>>>>
>>>>> (Table 7, Section "Pin Signals", page 56 of Arasan "SD3.0/SDIO3.0/eMMC4.4
>>>>> AHB Host Controller", revision 6.0 document)
>>>>>
>>>>> In some platforms those signals are connected to registers that need to
>>>>> be programmed at some point for proper driver/HW initialisation.
>>>>>
>>>>> I found that the 'struct sdhci_ops' contains a '.platform_init' callback
>>>>> that is called from within 'sdhci_pltfm_init', and that seems a good
>>>>> candidate for a place to program those registers (*).
>>>>>
>>>>> Do you agree?
>>>
>>> We already killed .platform_init
>>
>> I just saw that, yet it was the perfect place for the HW initialisation I'm
>> talking about.
>> Any way we can restore it?
>
> It doesn't serve any purpose I am aware of.

It would serve (for me) if it was there :-)

>
>>
>>>
>>> What is wrong with sdhci_arasan_probe()?
>>
>> Well, in 4.7 sdhci_arasan_probe() did not call of_match_device(), so I had
>> put a call to it just before sdhci_pltfm_init(), something like:
>>
>> +static const struct of_device_id sdhci_arasan_of_match[] = {
>> + {
>> + .compatible = "arasan,sdhci-8.9a",
>> + .data = &sdhci_arasan_ops,
>> + },
>> + {
>> + .compatible = "arasan,sdhci-5.1",
>> + .data = &sdhci_arasan_ops,
>> + },
>> + {
>> + .compatible = "arasan,sdhci-4.9a",
>> + .data = &sdhci_arasan_ops,
>> + },
>> + {
>> + .compatible = "sigma,smp8734-sdio",
>> + .data = &sdhci_arasan_tango4_ops,
>> + },
>> + { }
>> +};
>> +MODULE_DEVICE_TABLE(of, sdhci_arasan_of_match);
>>
>> ...
>>
>> + const struct of_device_id *match;
>> +
>> + match = of_match_device(sdhci_arasan_of_match, &pdev->dev);
>> + if (match)
>> + sdhci_arasan_pdata.ops = match->data;
>>
>> where 'sdhci_arasan_tango4_ops' contained a pointer to a .platform_init
>> callback.
>>
>> However, as I stated earlier, an upstream commit:
>>
>> commit 3ea4666e8d429223fbb39c1dccee7599ef7657d5
>> Author: Douglas Anderson <dianders@chromium.org>
>> Date: Mon Jun 20 10:56:47 2016 -0700
>>
>> mmc: sdhci-of-arasan: Properly set corecfg_baseclkfreq on rk3399
>>
>> changed struct 'sdhci_arasan_of_match' to convey different data, which
>> means that instead of having a generic way of accessing such data (such
>> as 'of_match_device()' and ".data" field), one must also check for
>> specific "compatible" strings to make sense of the ".data" field, such as
>> "rockchip,rk3399-sdhci-5.1"
>>
>> With the current code:
>> - there's no 'of_match_device()' before 'sdhci_pltfm_init()'
>> - the sdhci_pltfm_init() call is made with a static 'sdhci_arasan_pdata'
>> struct (so it cannot be made dependent on the "compatible" string).
>> - since 'sdhci_arasan_pdata' is the same for all compatible devices, even
>> for those that require special handling, more "compatible" matching code is
>> required
>> - leading to spread "compatible" matching code; IMHO it would be cleaner if
>> the 'sdhci_arasan_probe()' code was generic, with just a generic "compatible"
>> matching, which then proceeded with specific initialisation and generic
>> initialisation.
>>
>> In a nutshell, IMHO it would be better if adding support for more SoCs only
>> involved changing just 'sdhci_arasan_of_match' without the need to change
>> 'sdhci_arasan_probe()'.
>> That would clearly separate the generic and "SoC"-specific code, thus allowing
>> better maintenance.
>>
>> Does that makes sense to you guys?
>
> If you want to do that, then why not define your match data with your own
> callbacks. e.g. something like
>
> struct sdhci_arasan_of_data {
> struct sdhci_arasan_soc_ctl_map *soc_ctl_map;
> void (*platform_init)(struct sdhci_arasan_data *sdhci_arasan);
> };
>
> struct sdhci_arasan_of_data *data;
>
> data = match->data;
> sdhci_arasan->soc_ctl_map = data->soc_ctl_map;
> if (data->platform_init)
> platform_init(sdhci_arasan);

Well, that adds a level in the hierarchy, but here is what it would look like:


diff --git a/drivers/mmc/host/sdhci-of-arasan.c b/drivers/mmc/host/sdhci-of-arasan.c
index 410a55b..1cb3861 100644
--- a/drivers/mmc/host/sdhci-of-arasan.c
+++ b/drivers/mmc/host/sdhci-of-arasan.c
@@ -382,22 +382,6 @@ static int sdhci_arasan_resume(struct device *dev)
static SIMPLE_DEV_PM_OPS(sdhci_arasan_dev_pm_ops, sdhci_arasan_suspend,
sdhci_arasan_resume);

-static const struct of_device_id sdhci_arasan_of_match[] = {
- /* SoC-specific compatible strings w/ soc_ctl_map */
- {
- .compatible = "rockchip,rk3399-sdhci-5.1",
- .data = &rk3399_soc_ctl_map,
- },
-
- /* Generic compatible below here */
- { .compatible = "arasan,sdhci-8.9a" },
- { .compatible = "arasan,sdhci-5.1" },
- { .compatible = "arasan,sdhci-4.9a" },
-
- { /* sentinel */ }
-};
-MODULE_DEVICE_TABLE(of, sdhci_arasan_of_match);
-
/**
* sdhci_arasan_sdcardclk_recalc_rate - Return the card clock rate
*
@@ -578,6 +562,53 @@ static void sdhci_arasan_unregister_sdclk(struct device *dev)
of_clk_del_provider(dev->of_node);
}

+static void sdhci_tango4_platform_init(struct sdhci_host *host)
+{
+ printk("%s\n", __func__);
+
+ /*
+ pad_mode[2:0]=0 must be 0
+ sel_sdio[3]=1 must be 1 for SDIO
+ inv_sdwp_pol[4]=0 if set inverts the SD write protect polarity
+ inv_sdcd_pol[5]=0 if set inverts the SD card present polarity
+ */
+ sdhci_writel(host, 0x00000008, 0x100 + 0x0);
+}
+
+struct sdhci_arasan_chip_specific_data {
+ const struct sdhci_arasan_soc_ctl_map *soc_ctl_map;
+ void (*platform_init)(struct sdhci_host *host);
+};
+
+static const struct sdhci_arasan_chip_specific_data sdhci_arasan_rockchip = {
+ .soc_ctl_map = &rk3399_soc_ctl_map,
+};
+
+static const struct sdhci_arasan_chip_specific_data sdhci_arasan_sigma = {
+ .platform_init = sdhci_tango4_platform_init,
+};
+
+static const struct of_device_id sdhci_arasan_of_match[] = {
+ /* SoC-specific compatible strings w/ soc_ctl_map */
+ {
+ .compatible = "rockchip,rk3399-sdhci-5.1",
+ .data = &sdhci_arasan_rockchip,
+ },
+ {
+ .compatible = "sigma,sdio-v1",
+ .data = &sdhci_arasan_sigma,
+ },
+
+ /* Generic compatible below here */
+ { .compatible = "arasan,sdhci-8.9a" },
+ { .compatible = "arasan,sdhci-5.1" },
+ { .compatible = "arasan,sdhci-4.9a" },
+
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, sdhci_arasan_of_match);
+
+
static int sdhci_arasan_probe(struct platform_device *pdev)
{
int ret;
@@ -587,6 +618,7 @@ static int sdhci_arasan_probe(struct platform_device *pdev)
struct sdhci_host *host;
struct sdhci_pltfm_host *pltfm_host;
struct sdhci_arasan_data *sdhci_arasan;
+ struct sdhci_arasan_chip_specific_data *sdhci_arasan_chip_specific;
struct device_node *np = pdev->dev.of_node;

host = sdhci_pltfm_init(pdev, &sdhci_arasan_pdata,
@@ -599,7 +631,11 @@ static int sdhci_arasan_probe(struct platform_device *pdev)
sdhci_arasan->host = host;

match = of_match_node(sdhci_arasan_of_match, pdev->dev.of_node);
- sdhci_arasan->soc_ctl_map = match->data;
+ sdhci_arasan_chip_specific = (struct sdhci_arasan_chip_specific_data *)match;
+ if (sdhci_arasan_chip_specific->soc_ctl_map)
+ sdhci_arasan->soc_ctl_map = sdhci_arasan_chip_specific->soc_ctl_map;
+ if (sdhci_arasan_chip_specific->platform_init)
+ sdhci_arasan_chip_specific->platform_init(host);

node = of_parse_phandle(pdev->dev.of_node, "arasan,soc-ctl-syscon", 0);
if (node) {

I will try to send another patch with what a different approach

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