Re: [PATCH v4 3/5] usb: misc: eud: Add driver support for SM6115 / SM4250

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On 5.05.2023 17:50, Bhupesh Sharma wrote:
> On Fri, 5 May 2023 at 16:35, Konrad Dybcio <konrad.dybcio@xxxxxxxxxx> wrote:
>>
>> On 5.05.2023 08:40, Bhupesh Sharma wrote:
>>> Add SM6115 / SM4250 SoC EUD support in qcom_eud driver.
>>>
>>> On some SoCs (like the SM6115 / SM4250 SoC), the mode manager
>>> needs to be accessed only via the secure world (through 'scm'
>>> calls).
>>>
>>> Also, the enable bit inside 'tcsr_check_reg' needs to be set
>>> first to set the eud in 'enable' mode on these SoCs.
>>>
>>> Since this difference comes from how the firmware is configured, so
>>> the driver now relies on the presence of an extra boolean DT property
>>> to identify if secure access is needed.
>>>
>>> Signed-off-by: Bhupesh Sharma <bhupesh.sharma@xxxxxxxxxx>
>>> ---
>>>  drivers/usb/misc/Kconfig    |  1 +
>>>  drivers/usb/misc/qcom_eud.c | 74 +++++++++++++++++++++++++++++++++----
>>>  2 files changed, 68 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/drivers/usb/misc/Kconfig b/drivers/usb/misc/Kconfig
>>> index 99b15b77dfd5..fe1b5fec1dfc 100644
>>> --- a/drivers/usb/misc/Kconfig
>>> +++ b/drivers/usb/misc/Kconfig
>>> @@ -147,6 +147,7 @@ config USB_APPLEDISPLAY
>>>  config USB_QCOM_EUD
>>>       tristate "QCOM Embedded USB Debugger(EUD) Driver"
>>>       depends on ARCH_QCOM || COMPILE_TEST
>>> +     select QCOM_SCM
>>>       select USB_ROLE_SWITCH
>>>       help
>>>         This module enables support for Qualcomm Technologies, Inc.
>>> diff --git a/drivers/usb/misc/qcom_eud.c b/drivers/usb/misc/qcom_eud.c
>>> index b7f13df00764..18a2dee3b4b9 100644
>>> --- a/drivers/usb/misc/qcom_eud.c
>>> +++ b/drivers/usb/misc/qcom_eud.c
>>> @@ -5,12 +5,14 @@
>>>
>>>  #include <linux/bitops.h>
>>>  #include <linux/err.h>
>>> +#include <linux/firmware/qcom/qcom_scm.h>
>>>  #include <linux/interrupt.h>
>>>  #include <linux/io.h>
>>>  #include <linux/iopoll.h>
>>>  #include <linux/kernel.h>
>>>  #include <linux/module.h>
>>>  #include <linux/of.h>
>>> +#include <linux/of_device.h>
>>>  #include <linux/platform_device.h>
>>>  #include <linux/slab.h>
>>>  #include <linux/sysfs.h>
>>> @@ -22,23 +24,35 @@
>>>  #define EUD_REG_VBUS_INT_CLR 0x0080
>>>  #define EUD_REG_CSR_EUD_EN   0x1014
>>>  #define EUD_REG_SW_ATTACH_DET        0x1018
>>> -#define EUD_REG_EUD_EN2        0x0000
>>> +#define EUD_REG_EUD_EN2              0x0000
>>>
>>>  #define EUD_ENABLE           BIT(0)
>>> -#define EUD_INT_PET_EUD      BIT(0)
>>> +#define EUD_INT_PET_EUD              BIT(0)
>>>  #define EUD_INT_VBUS         BIT(2)
>>>  #define EUD_INT_SAFE_MODE    BIT(4)
>>>  #define EUD_INT_ALL          (EUD_INT_VBUS | EUD_INT_SAFE_MODE)
>>>
>>> +#define EUD_EN2_SECURE_EN    BIT(0)
>>> +#define EUD_EN2_NONSECURE_EN (1)
>> BIT(0) == 1, is that actually a separate register or does it just
>> reflect whether scm_writel is used?
>>
>> If the latter, perhaps it'd be okay to just call it EUD_EN2_EN or
>> something along those lines? Isn't that perhaps what the docs call it?
> 
> Ok, let's name it as EUD_EN2_ENABLE then.
> 
>>> +#define EUD_EN2_DISABLE              (0)
>>> +#define TCSR_CHECK_EN                BIT(0)
>>> +
>>> +struct eud_soc_cfg {
>>> +     u32 tcsr_check_offset;
>>> +};
>>> +
>>>  struct eud_chip {
>>>       struct device                   *dev;
>>>       struct usb_role_switch          *role_sw;
>>> +     const struct eud_soc_cfg        *eud_cfg;
>>>       void __iomem                    *base;
>>>       void __iomem                    *mode_mgr;
>>>       unsigned int                    int_status;
>>>       int                             irq;
>>>       bool                            enabled;
>>>       bool                            usb_attached;
>>> +     bool                            secure_mode_enable;
>> Since it's only used in the probe function now, we can get rid
>> of it!
> 
> Ok.
> 
>>> +     phys_addr_t                     secure_mode_mgr;
>>>  };
>>>
>>>  static int enable_eud(struct eud_chip *priv)
>>> @@ -46,7 +60,11 @@ static int enable_eud(struct eud_chip *priv)
>>>       writel(EUD_ENABLE, priv->base + EUD_REG_CSR_EUD_EN);
>>>       writel(EUD_INT_VBUS | EUD_INT_SAFE_MODE,
>>>                       priv->base + EUD_REG_INT1_EN_MASK);
>>> -     writel(1, priv->mode_mgr + EUD_REG_EUD_EN2);
>>> +
>>> +     if (priv->secure_mode_mgr)
>>> +             qcom_scm_io_writel(priv->secure_mode_mgr + EUD_REG_EUD_EN2, EUD_EN2_SECURE_EN);
>>> +     else
>>> +             writel(EUD_EN2_NONSECURE_EN, priv->mode_mgr + EUD_REG_EUD_EN2);
>>>
>>>       return usb_role_switch_set_role(priv->role_sw, USB_ROLE_DEVICE);
>>>  }
>>> @@ -54,7 +72,11 @@ static int enable_eud(struct eud_chip *priv)
>>>  static void disable_eud(struct eud_chip *priv)
>>>  {
>>>       writel(0, priv->base + EUD_REG_CSR_EUD_EN);
>>> -     writel(0, priv->mode_mgr + EUD_REG_EUD_EN2);
>>> +
>>> +     if (priv->secure_mode_mgr)
>>> +             qcom_scm_io_writel(priv->secure_mode_mgr + EUD_REG_EUD_EN2, EUD_EN2_DISABLE);
>>> +     else
>>> +             writel(EUD_EN2_DISABLE, priv->mode_mgr + EUD_REG_EUD_EN2);
>>>  }
>>>
>>>  static ssize_t enable_show(struct device *dev,
>>> @@ -178,6 +200,8 @@ static void eud_role_switch_release(void *data)
>>>  static int eud_probe(struct platform_device *pdev)
>>>  {
>>>       struct eud_chip *chip;
>>> +     struct resource *res;
>>> +     phys_addr_t tcsr_base, tcsr_check;
>>>       int ret;
>>>
>>>       chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
>>> @@ -200,9 +224,40 @@ static int eud_probe(struct platform_device *pdev)
>>>       if (IS_ERR(chip->base))
>>>               return PTR_ERR(chip->base);
>>>
>>> -     chip->mode_mgr = devm_platform_ioremap_resource(pdev, 1);
>>> -     if (IS_ERR(chip->mode_mgr))
>>> -             return PTR_ERR(chip->mode_mgr);
>>> +     chip->secure_mode_enable = of_property_read_bool(chip->dev->of_node,
>>> +                                             "qcom,secure-mode-enable");
>>> +     /*
>>> +      * EUD block on a few Qualcomm SoCs need secure register access.
>>> +      * Check for the same.
>>> +      */
>>> +     if (chip->secure_mode_enable) {
>> if (of_property_read_bool...)
> 
> Sure.
> 
>>> +             res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
>>> +             if (!res)
>>> +                     return dev_err_probe(chip->dev, -ENODEV,
>>> +                                          "failed to get secure_mode_mgr reg base\n");
>>> +
>>> +             chip->secure_mode_mgr = res->start;
>>> +     } else {
>>> +             chip->mode_mgr = devm_platform_ioremap_resource(pdev, 1);
>>> +             if (IS_ERR(chip->mode_mgr))
>>> +                     return PTR_ERR(chip->mode_mgr);
>>> +     }
>>> +
>>> +     /* Check for any SoC specific config data */
>>> +     chip->eud_cfg = of_device_get_match_data(&pdev->dev);
>>> +     if (chip->eud_cfg) {
>>> +             res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "tcsr-base");
>>> +             if (!res)
>>> +                     return dev_err_probe(chip->dev, -ENODEV,
>>> +                                          "failed to get tcsr reg base\n");
>>> +
>>> +             tcsr_base = res->start;
>> This variable does not seem very useful, we can get rid of it.
> 
> Ok.
> 
>>> +             tcsr_check = tcsr_base + chip->eud_cfg->tcsr_check_offset;
>>> +
>>> +             ret = qcom_scm_io_writel(tcsr_check, TCSR_CHECK_EN);
>>> +             if (ret)
>>> +                     return dev_err_probe(chip->dev, ret, "failed to write tcsr check reg\n");
>>> +     }
>>>
>>>       chip->irq = platform_get_irq(pdev, 0);
>>>       ret = devm_request_threaded_irq(&pdev->dev, chip->irq, handle_eud_irq,
>>> @@ -230,8 +285,13 @@ static int eud_remove(struct platform_device *pdev)
>>>       return 0;
>>>  }
>>>
>>> +static const struct eud_soc_cfg sm6115_eud_cfg = {
>> This could be marked __initconst, but I'm not sure if future
>> additions won't need to be accessed after the driver has already
>> gone through its probe function.. Your call!
> 
> Like Dmitry also mentioned, I have my apprehensions as well marking this
> as __initconst, so let's not do that.
Right, thanks Dmitry for pointing this out, I didn't think of usecases
where a driver can be removed..

Konrad
> 
> I will wait for a few more comments and then will send a new version across.
> 
> Thanks,
> Bhupesh
> 
>>> +     .tcsr_check_offset = 0x25018,
>>> +};
>>> +
>>>  static const struct of_device_id eud_dt_match[] = {
>>>       { .compatible = "qcom,sc7280-eud" },
>>> +     { .compatible = "qcom,sm6115-eud", .data = &sm6115_eud_cfg },
>>>       { }
>>>  };
>>>  MODULE_DEVICE_TABLE(of, eud_dt_match);



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