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

From: Bhupesh Sharma
Date: Fri May 05 2023 - 11:51:10 EST

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.

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);