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

From: Konrad Dybcio
Date: Fri May 05 2023 - 14:32:17 EST



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);