Re: [PATCHv2 1/2] extcon: add driver for Intel USB mux

[Chanwoo Choi <cw00.choi@samsung.com>]

Hi Heikki,

I'm sorry for delay reply.

On 2015년 12월 03일 18:29, Heikki Krogerus wrote:
> Several Intel PCHs and SOCs have an internal mux that is
> used to share one USB port between USB Device Controller and
> xHCI. The mux is normally handled by System FW/BIOS, but not
> always. For those platforms where the FW does not take care
> of the mux, this driver is needed.
> 
> Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> ---
>  drivers/extcon/Kconfig               |   5 ++
>  drivers/extcon/Makefile              |   1 +
>  drivers/extcon/extcon-intel-usb.c    | 118 +++++++++++++++++++++++++++++++++++
>  include/linux/extcon/intel_usb_mux.h |  31 +++++++++
>  4 files changed, 155 insertions(+)
>  create mode 100644 drivers/extcon/extcon-intel-usb.c
>  create mode 100644 include/linux/extcon/intel_usb_mux.h
> 
> diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig
> index 0cebbf6..0a7ccb1 100644
> --- a/drivers/extcon/Kconfig
> +++ b/drivers/extcon/Kconfig
> @@ -118,3 +118,8 @@ config EXTCON_USB_GPIO
>  	  Used typically if GPIO is used for USB ID pin detection.
>  
>  endif
> +
> +config EXTCON_INTEL_USB
> +	bool
> +	depends on X86 && USB
> +	select EXTCON
> diff --git a/drivers/extcon/Makefile b/drivers/extcon/Makefile
> index ba787d0..e6e031a 100644
> --- a/drivers/extcon/Makefile
> +++ b/drivers/extcon/Makefile
> @@ -15,3 +15,4 @@ obj-$(CONFIG_EXTCON_PALMAS)	+= extcon-palmas.o
>  obj-$(CONFIG_EXTCON_RT8973A)	+= extcon-rt8973a.o
>  obj-$(CONFIG_EXTCON_SM5502)	+= extcon-sm5502.o
>  obj-$(CONFIG_EXTCON_USB_GPIO)	+= extcon-usb-gpio.o
> +obj-$(CONFIG_EXTCON_INTEL_USB)	+= extcon-intel-usb.o
> diff --git a/drivers/extcon/extcon-intel-usb.c b/drivers/extcon/extcon-intel-usb.c
> new file mode 100644
> index 0000000..3da6039
> --- /dev/null
> +++ b/drivers/extcon/extcon-intel-usb.c
> @@ -0,0 +1,118 @@
> +/**
> + * extcon-intel-usb.c - Driver for Intel USB mux
> + *
> + * Copyright (C) 2015 Intel Corporation
> + * Author: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/slab.h>
> +#include <linux/extcon.h>
> +
> +#include <linux/extcon/intel_usb_mux.h>
> +
> +#define INTEL_MUX_CFG0		0x00
> +#define INTEL_MUX_CFG1		0x04
> +
> +#define CFG0_SW_DRD_MODE_MASK	0x3
> +#define CFG0_SW_DRD_DYN		0
> +#define CFG0_SW_DRD_STATIC_HOST	1
> +#define CFG0_SW_DRD_STATIC_DEV	2
> +#define CFG0_SW_SYNC_SS_AND_HS	BIT(2)
> +#define CFG0_SW_SWITCH_EN	BIT(16)
> +#define CFG0_SW_IDPIN		BIT(20)
> +#define CFG0_SW_IDPIN_EN	BIT(21)
> +#define CFG0_SW_VBUS_VALID	BIT(24)
> +
> +#define CFG1_MODE		BIT(29)
> +
> +struct intel_usb_mux {
> +	struct notifier_block nb;
> +	struct extcon_dev edev;
> +	void __iomem *regs;
> +	u32 cfg0_ctx;
> +};
> +
> +static const int intel_mux_cable[] = {
> +	EXTCON_USB_HOST,
> +	EXTCON_NONE,
> +};
> +
> +static int intel_usb_mux_notifier(struct notifier_block *nb,
> +				  unsigned long old, void *ptr)
> +{
> +	struct intel_usb_mux *mux = container_of(nb, struct intel_usb_mux, nb);
> +	u32 val;
> +
> +	if (mux->edev.state)
> +		val = CFG0_SW_IDPIN_EN | CFG0_SW_DRD_STATIC_HOST;
> +	else
> +		val = CFG0_SW_IDPIN_EN | CFG0_SW_IDPIN | CFG0_SW_VBUS_VALID |
> +		      CFG0_SW_DRD_STATIC_DEV;
> +
> +	writel(val, mux->regs);
> +	return NOTIFY_OK;
> +}
> +
> +struct intel_usb_mux *intel_usb_mux_register(struct device *dev,
> +					     struct resource *r)
> +{
> +	struct intel_usb_mux *mux;
> +	int ret;
> +
> +	mux = kzalloc(sizeof(*mux), GFP_KERNEL);
> +	if (!mux)
> +		return ERR_PTR(-ENOMEM);
> +
> +	mux->regs = ioremap_nocache(r->start, resource_size(r));
> +	if (!mux->regs) {
> +		kfree(mux);
> +		return ERR_PTR(-ENOMEM);
> +	}
> +
> +	mux->cfg0_ctx = readl(mux->regs + INTEL_MUX_CFG0);
> +
> +	mux->edev.dev.parent = dev;
> +	mux->edev.supported_cable = intel_mux_cable;
> +
> +	ret = extcon_dev_register(&mux->edev);
> +	if (ret)
> +		goto err;
> +
> +	mux->edev.name = "intel_usb_mux";
> +	mux->edev.state = !!(readl(mux->regs + INTEL_MUX_CFG1) & CFG1_MODE);
> +
> +	/* An external source needs to tell us what to do */
> +	mux->nb.notifier_call = intel_usb_mux_notifier;
> +	ret = extcon_register_notifier(&mux->edev, EXTCON_USB_HOST, &mux->nb);
> +	if (ret) {
> +		dev_err(&mux->edev.dev, "failed to register notifier\n");
> +		extcon_dev_unregister(&mux->edev);
> +		goto err;
> +	}
> +	return mux;
> +err:
> +	iounmap(mux->regs);
> +	kfree(mux);
> +	return ERR_PTR(ret);
> +}
> +EXPORT_SYMBOL_GPL(intel_usb_mux_register);
> +
> +void intel_usb_mux_unregister(struct intel_usb_mux *mux)
> +{
> +	if (!mux)
> +		return;
> +
> +	if (WARN_ON(IS_ERR_OR_NULL(extcon_get_extcon_dev(mux->edev.name))))
> +		return;
> +
> +	extcon_unregister_notifier(&mux->edev, EXTCON_USB_HOST, &mux->nb);
> +	extcon_dev_unregister(&mux->edev);
> +	writel(mux->cfg0_ctx, mux->regs + INTEL_MUX_CFG0);
> +	iounmap(mux->regs);
> +	kfree(mux);
> +}
> +EXPORT_SYMBOL_GPL(intel_usb_mux_unregister);

I do never want to add some specific funtcion for only this driver.
I think is not appropriate way.
- intel_usb_mux_unregister
- intel_usb_mux_register

The client driver using extcon driver should use the standard extcon API
for code consistency. Also, I'll do the more detailed review for this patch.

> diff --git a/include/linux/extcon/intel_usb_mux.h b/include/linux/extcon/intel_usb_mux.h
> new file mode 100644
> index 0000000..f18ce52
> --- /dev/null
> +++ b/include/linux/extcon/intel_usb_mux.h
> @@ -0,0 +1,31 @@
> +/*
> + * Driver for Intel USB mux
> + *
> + * Copyright (C) 2015 Intel Corporation
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#ifndef _INTEL_USB_MUX_H
> +#define _INTEL_USB_MUX_H
> +
> +#include <linux/errno.h>
> +
> +struct intel_usb_mux;
> +
> +#ifdef CONFIG_EXTCON_INTEL_USB
> +struct intel_usb_mux *intel_usb_mux_register(struct device *dev,
> +					     struct resource *r);
> +void intel_usb_mux_unregister(struct intel_usb_mux *mux);
> +#else
> +static inline struct intel_usb_mux *intel_usb_mux_register(struct device *dev,
> +							   struct resource *r)
> +{
> +	return ERR_PTR(-ENOTSUPP);
> +}
> +static inline void intel_usb_mux_unregister(struct intel_usb_mux *mux) { }

ditto.

> +#endif /* CONFIG_EXTCON_INTEL_USB */
> +
> +#endif /* _INTEL_USB_MUX_H */
> 

Thanks,
Chanwoo Choi