Re: [PATCH v6 4/6] usb: misc: eud: Add driver support for SM6115 / SM4250
From: Bhupesh Sharma
Date: Thu May 18 2023 - 06:38:20 EST
On Thu, 18 May 2023 at 15:58, Konrad Dybcio <konrad.dybcio@xxxxxxxxxx> wrote:
>
> On 17.05.2023 23:17, 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.
> >
> > Signed-off-by: Bhupesh Sharma <bhupesh.sharma@xxxxxxxxxx>
> > ---
> > drivers/usb/misc/Kconfig | 2 +-
> > drivers/usb/misc/qcom_eud.c | 65 ++++++++++++++++++++++++++++++++++---
> > 2 files changed, 61 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/usb/misc/Kconfig b/drivers/usb/misc/Kconfig
> > index 99b15b77dfd5..51eb5140caa1 100644
> > --- a/drivers/usb/misc/Kconfig
> > +++ b/drivers/usb/misc/Kconfig
> > @@ -146,7 +146,7 @@ config USB_APPLEDISPLAY
> >
> > config USB_QCOM_EUD
> > tristate "QCOM Embedded USB Debugger(EUD) Driver"
> > - depends on ARCH_QCOM || COMPILE_TEST
> > + depends on (ARCH_QCOM && QCOM_SCM) || COMPILE_TEST
> > 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 74f2aeaccdcb..6face21b7fb7 100644
> > --- a/drivers/usb/misc/qcom_eud.c
> > +++ b/drivers/usb/misc/qcom_eud.c
> > @@ -11,9 +11,11 @@
> > #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>
> > +#include <linux/firmware/qcom/qcom_scm.h>
> > #include <linux/usb/role.h>
> >
> > #define EUD_REG_INT1_EN_MASK 0x0024
> > @@ -30,15 +32,25 @@
> > #define EUD_INT_SAFE_MODE BIT(4)
> > #define EUD_INT_ALL (EUD_INT_VBUS | EUD_INT_SAFE_MODE)
> >
> > +#define EUD_EN2_EN BIT(0)
> > +#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;
> > + phys_addr_t secure_mode_mgr;
> > };
> >
> > static int enable_eud(struct eud_chip *priv)
> > @@ -46,7 +58,11 @@ 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_EN);
> > + else
> > + writel(EUD_EN2_EN, priv->mode_mgr + EUD_REG_EUD_EN2);
> >
> > return usb_role_switch_set_role(priv->role_sw, USB_ROLE_DEVICE);
> > }
> > @@ -54,7 +70,11 @@ 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 +198,8 @@ 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_check;
> > int ret;
> >
> > chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
> > @@ -200,9 +222,37 @@ 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);
> > + /*
> > + * EUD block on a few Qualcomm SoCs needs secure register access.
> > + * Check for the same.
> > + */
> > + if (of_device_is_compatible(chip->dev->of_node, "qcom,sm6115-eud")) {
> I didn't notice that this changed between v4 and v5, but in my v4 review
> I suggested using
>
> if (of_property_read_bool(chip->dev->of_node, "qcom,secure-mode-enable"))
>
> as this was the only place where the value of that function was checked
> and caching it in the driver struct simply made no sense (as of today, anyway)
>
> checking the device compatible does not scale very well for something
> generic, as now it'd require adding each qcom,smABCD-eud to this condition
> as well.
>
> > + 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");
> This suggests the reg-name is "secure_mode_mgr" which is not true,
> according to your binding patch. I thought about adding a separate
> entry, but ultimately this would be against the DT philosophy, as it
> references the same physical region as "eud-mode-mgr", just that due
> to ACL software running at a higher exception level it's not
> directly accessible..
>
> I was debating suggesting moving it to SoC configuration, but that
> also depends on the software stack (e.g. there are windows and cros
> 7280 laptops with different security restrictions).. so I think
> the dt property is the way to go.
Well, the changes were done as per Krzysztof's comments on the earlier
versions (see [1] and [2]):
[1]. https://lore.kernel.org/linux-arm-msm/fe326d38-ee52-b0a4-21d8-f00f22449417@xxxxxxxxxx/
[2]. https://lore.kernel.org/linux-arm-msm/e60af365-4260-a56f-1ec1-c7c60d172b38@xxxxxxxxxx/
I am fine with either approach. As I originally argued, having a
dt-property seems more useful to me to indicate a secure-mode access.
May be @Krzysztof Kozlowski , can share his opinions on the same.
Thanks,
Bhupesh