Re: [PATCH V0 4/7] usb: common: eud: Added the driver support for Embedded USB Debugger(EUD)

Greg KH
2021-10-04T11:31:39Z

On Mon, Oct 04, 2021 at 04:46:22PM +0530, Souradeep Chowdhury wrote:
> Add support for control peripheral of EUD (Embedded USB Debugger) to
> listen to events such as USB attach/detach, pet EUD to indicate software
> is functional.Reusing the platform device kobj, sysfs entry 'enable' is
> created to enable or disable EUD.
>
> To enable the eud the following needs to be done
> echo 1 > /sys/bus/platform/.../enable
>
> To disable eud, following is the command
> echo 0 > /sys/bus/platform/.../enable
>
> Signed-off-by: Souradeep Chowdhury <schowdhu@codeaurora.org>
> ---
> Documentation/ABI/testing/sysfs-driver-eud | 7 +
> drivers/usb/common/Kconfig | 9 +
> drivers/usb/common/Makefile | 1 +
> drivers/usb/common/qcom_eud.c | 256 +++++++++++++++++++++++++++++
> 4 files changed, 273 insertions(+)
> create mode 100644 Documentation/ABI/testing/sysfs-driver-eud
> create mode 100644 drivers/usb/common/qcom_eud.c
>
> diff --git a/Documentation/ABI/testing/sysfs-driver-eud b/Documentation/ABI/testing/sysfs-driver-eud
> new file mode 100644
> index 0000000..14a02da
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-driver-eud
> @@ -0,0 +1,7 @@
> +What: /sys/bus/platform/.../enable

Um, that's a _very_ generic regex, you just matched with any platform
device that might have a "enable" sysfs entry :(

Please use the dwc's name in here to help out with figuring this out.

> +Date: October 2021
> +Contact: Souradeep Chowdhury <schowdhu@codeaurora.org>

No tabs?

> +Description:
> + The Enable/Disable sysfs interface for Embedded
> + USB Debugger(EUD).This enables and disables the
> + EUD based on a 1 or a 0 value.

What does enabling or disabling actually do?

And please use a ' ' after a '.'.

> diff --git a/drivers/usb/common/Kconfig b/drivers/usb/common/Kconfig
> index 5e8a04e..669b3fe 100644
> --- a/drivers/usb/common/Kconfig
> +++ b/drivers/usb/common/Kconfig
> @@ -50,3 +50,12 @@ config USB_CONN_GPIO
>
> To compile the driver as a module, choose M here: the module will
> be called usb-conn-gpio.ko
> +
> +config USB_QCOM_EUD
> + tristate "USB EUD Driver"
> + select USB_ROLE_SWITCH
> + help
> + This module enables support for Qualcomm Technologies, Inc.
> + Embedded USB Debugger (EUD). The EUD is a control peripheral
> + which reports VBUS attach/detach events and has USB-based
> + debug and trace capabilities.

What is the module name if this is built?

> diff --git a/drivers/usb/common/Makefile b/drivers/usb/common/Makefile
> index 8ac4d21..eb66045 100644
> --- a/drivers/usb/common/Makefile
> +++ b/drivers/usb/common/Makefile
> @@ -11,3 +11,4 @@ usb-common-$(CONFIG_USB_LED_TRIG) += led.o
> obj-$(CONFIG_USB_CONN_GPIO) += usb-conn-gpio.o
> obj-$(CONFIG_USB_OTG_FSM) += usb-otg-fsm.o
> obj-$(CONFIG_USB_ULPI_BUS) += ulpi.o
> +obj-$(CONFIG_USB_QCOM_EUD) += qcom_eud.o
> diff --git a/drivers/usb/common/qcom_eud.c b/drivers/usb/common/qcom_eud.c
> new file mode 100644
> index 0000000..7a92fff
> --- /dev/null
> +++ b/drivers/usb/common/qcom_eud.c
> @@ -0,0 +1,256 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2015-2021, The Linux Foundation. All rights reserved.
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/delay.h>
> +#include <linux/err.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/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/sysfs.h>
> +#include <linux/usb/role.h>
> +
> +#define EUD_REG_INT1_EN_MASK 0x0024
> +#define EUD_REG_INT_STATUS_1 0x0044
> +#define EUD_REG_CTL_OUT_1 0x0074
> +#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_ENABLE 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)
> +
> +struct eud_chip {
> + struct device *dev;
> + struct usb_role_switch *role_sw;
> + void __iomem *eud_reg_base;
> + void __iomem *eud_mode_mgr2_phys_base;
> + unsigned int int_status;
> + int enable;

bool?

> + int eud_irq;
> + bool usb_attach;
> +

No need for a blank line.

> +};
> +
> +static int enable_eud(struct eud_chip *priv)
> +{
> + writel(EUD_ENABLE, priv->eud_reg_base + EUD_REG_CSR_EUD_EN);
> + writel(EUD_INT_VBUS | EUD_INT_SAFE_MODE,
> + priv->eud_reg_base + EUD_REG_INT1_EN_MASK);
> + writel(1, priv->eud_mode_mgr2_phys_base + EUD_REG_EUD_EN2);
> +
> + return usb_role_switch_set_role(priv->role_sw, USB_ROLE_DEVICE);
> +}
> +
> +static void disable_eud(struct eud_chip *priv)
> +{
> + writel(0, priv->eud_reg_base + EUD_REG_CSR_EUD_EN);
> + writel(0, priv->eud_mode_mgr2_phys_base + EUD_REG_EUD_EN2);
> +}
> +
> +static ssize_t enable_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct eud_chip *chip = dev_get_drvdata(dev);
> +
> + return sprintf(buf, "%d", chip->enable);

sysfs_emit() please.

> +}
> +
> +static ssize_t enable_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct eud_chip *chip = dev_get_drvdata(dev);
> + unsigned long enable;
> + int ret;
> +
> + if (kstrtoul(buf, 16, &enable))
> + return -EINVAL;

Use the default sysfs function to parse 0/1/y/n/Y/N please.

> +
> + if (enable == 1) {
> + ret = enable_eud(chip);
> + if (!ret)
> + chip->enable = enable;
> + } else if (enable == 0) {
> + disable_eud(chip);
> + } else {
> + return -EINVAL;
> + }
> +
> + return count;
> +}
> +
> +static DEVICE_ATTR_RW(enable);
> +
> +static const struct device_attribute *eud_attrs[] = {
> + &dev_attr_enable,
> + NULL,
> +};

You create a list of attributes and then never use it?

Who reviewed this thing?

You were so close in getting this right, see below...

> +
> +static void usb_attach_detach(struct eud_chip *chip)
> +{
> + u32 reg;
> +
> + /* read ctl_out_1[4] to find USB attach or detach event */
> + reg = readl(chip->eud_reg_base + EUD_REG_CTL_OUT_1);
> + if (reg & EUD_INT_SAFE_MODE)
> + chip->usb_attach = true;
> + else
> + chip->usb_attach = false;
> +
> + /* set and clear vbus_int_clr[0] to clear interrupt */
> + writel(BIT(0), chip->eud_reg_base + EUD_REG_VBUS_INT_CLR);
> + writel(0, chip->eud_reg_base + EUD_REG_VBUS_INT_CLR);
> +}
> +
> +static void pet_eud(struct eud_chip *chip)
> +{
> + u32 reg;
> + int ret;
> +
> + /* read sw_attach_det[0] to find attach/detach event */
> + reg = readl(chip->eud_reg_base + EUD_REG_SW_ATTACH_DET);
> + if (reg & EUD_INT_PET_EUD) {
> + /* Detach & Attach pet for EUD */
> + writel(0, chip->eud_reg_base + EUD_REG_SW_ATTACH_DET);
> + /* Delay to make sure detach pet is done before attach pet */
> + ret = readl_poll_timeout(chip->eud_reg_base + EUD_REG_SW_ATTACH_DET,
> + reg, (reg == 0), 1, 100);
> + if (ret) {
> + dev_err(chip->dev, "Detach pet failed\n");
> + return;
> + }
> +
> + writel(EUD_INT_PET_EUD, chip->eud_reg_base +
> + EUD_REG_SW_ATTACH_DET);
> + } else {
> + /* Attach pet for EUD */
> + writel(EUD_INT_PET_EUD, chip->eud_reg_base +
> + EUD_REG_SW_ATTACH_DET);
> + }
> +}
> +
> +static irqreturn_t handle_eud_irq(int irq, void *data)
> +{
> + struct eud_chip *chip = data;
> + u32 reg;
> +
> + /* read status register and find out which interrupt triggered */
> + reg = readl(chip->eud_reg_base + EUD_REG_INT_STATUS_1);
> + switch (reg & EUD_INT_ALL) {
> + case EUD_INT_VBUS:
> + chip->int_status = EUD_INT_VBUS;
> + usb_attach_detach(chip);
> + return IRQ_WAKE_THREAD;
> + case EUD_INT_SAFE_MODE:
> + pet_eud(chip);
> + break;
> + default:
> + return IRQ_NONE;
> + }
> + return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t handle_eud_irq_thread(int irq, void *data)
> +{
> + struct eud_chip *chip = data;
> + int ret;
> +
> + if (chip->int_status == EUD_INT_VBUS) {
> + if (chip->usb_attach)
> + ret = usb_role_switch_set_role(chip->role_sw, USB_ROLE_DEVICE);
> + else
> + ret = usb_role_switch_set_role(chip->role_sw, USB_ROLE_HOST);
> + if (ret)
> + dev_err(chip->dev, "failed to set role switch\n");
> + }
> +
> + return IRQ_HANDLED;
> +}
> +
> +static int eud_probe(struct platform_device *pdev)
> +{
> + struct eud_chip *chip;
> + int ret;
> +
> + chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
> + if (!chip)
> + return -ENOMEM;
> +
> + chip->dev = &pdev->dev;
> +
> + chip->role_sw = usb_role_switch_get(chip->dev);
> + if (IS_ERR(chip->role_sw)) {
> + if (PTR_ERR(chip->role_sw) != -EPROBE_DEFER)
> + dev_err(chip->dev, "failed to get role switch\n");
> +
> + return PTR_ERR(chip->role_sw);
> + }
> +
> + chip->eud_reg_base = devm_platform_ioremap_resource(pdev, 0);
> + if (IS_ERR(chip->eud_reg_base))
> + return PTR_ERR(chip->eud_reg_base);
> +
> + chip->eud_mode_mgr2_phys_base = devm_platform_ioremap_resource(pdev, 1);
> + if (IS_ERR(chip->eud_mode_mgr2_phys_base))
> + return PTR_ERR(chip->eud_mode_mgr2_phys_base);
> +
> + chip->eud_irq = platform_get_irq(pdev, 0);
> + ret = devm_request_threaded_irq(&pdev->dev, chip->eud_irq, handle_eud_irq,
> + handle_eud_irq_thread, IRQF_ONESHOT, NULL, chip);
> + if (ret)
> + return ret;
> +
> + device_init_wakeup(&pdev->dev, true);
> + enable_irq_wake(chip->eud_irq);
> +
> + platform_set_drvdata(pdev, chip);
> +
> + ret = device_create_file(&pdev->dev, eud_attrs[0]);

You raced with userspace and lost :(

Please properly attach the sysfs file to the platform driver to have the
driver core register this correctly.

> +
> + return ret;
> +}
> +
> +static int eud_remove(struct platform_device *pdev)
> +{
> + struct eud_chip *chip = platform_get_drvdata(pdev);
> +
> + if (chip->enable)
> + disable_eud(chip);
> +
> + device_remove_file(&pdev->dev, eud_attrs[0]);

No need for this if you do the above correctly.

> + device_init_wakeup(&pdev->dev, false);

Why is this needed?

thanks,

greg k-h