Re: [PATCH v4] extcon: Palmas Extcon Driver

[Kishon Vijay Abraham I]

Hi,

On Tuesday 07 May 2013 06:13 AM, myungjoo.ham wrote:
> > From: Graeme Gregory <gg@xxxxxxxxxxxxxxx>
> >
> > This is the driver for the USB comparator built into the palmas chip. It
> > handles the various USB OTG events that can be generated by cable
> > insertion/removal.
> >
> > Signed-off-by: Graeme Gregory <gg@xxxxxxxxxxxxxxx>
> > Signed-off-by: Moiz Sonasath <m-sonasath@xxxxxx>
> > Signed-off-by: Ruchika Kharwar <ruchika@xxxxxx>
> > Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx>
> > [kishon@xxxxxx: adapted palmas usb driver to use the extcon framework]
> > Signed-off-by: Sebastien Guiriec <s-guiriec@xxxxxx>
>
> Here goes some comments in the code:
>
> []
>
> > diff --git a/drivers/extcon/extcon-palmas.c
> b/drivers/extcon/extcon-palmas.c
> > new file mode 100644
> > index 0000000..3ef042f
> > --- /dev/null
> > +++ b/drivers/extcon/extcon-palmas.c
> > @@ -0,0 +1,389 @@
> > +/*
> > + * Palmas USB transceiver driver
> > + *
> > + * Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License as published by
> > + * the Free Software Foundation; either version 2 of the License, or
> > + * (at your option) any later version.
> > + *
> > + * Author: Graeme Gregory <gg@...mlogic.co.uk>
> > + * Author: Kishon Vijay Abraham I <kishon@...com>
> > + *
> > + * Based on twl6030_usb.c
> > + *
> > + * Author: Hema HK <hemahk@...com>
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > + * GNU General Public License for more details.
> > + */
>
> Why the email addresses are masked in the source code?
> (I'm just curious as this is the first time to see such in kernel source)

That was not intentional. Took the previous version from the net. My bad.
> > +
> > +#include <linux/module.h>
> > +#include <linux/init.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/io.h>
> > +#include <linux/usb/phy_companion.h>
> > +#include <linux/regulator/consumer.h>
> > +#include <linux/err.h>
> > +#include <linux/notifier.h>
> > +#include <linux/slab.h>
> > +#include <linux/delay.h>
> > +#include <linux/mfd/palmas.h>
> > +#include <linux/of.h>
> > +#include <linux/of_platform.h>
> > +#include <linux/extcon/extcon_palmas.h>
> > +
> > +static const char *palmas_extcon_cable[] = {
> > +	[0] = "USB",
> > +	[1] = "USB-HOST",
>
> 	[1] = "USB-Host",
>
> > +	NULL,
> > +};
> > +
> > +static const int mutually_exclusive[] = {0x3, 0x0};
> > +
> > +static void palmas_usb_wakeup(struct palmas *palmas, int enable)
> > +{
> > +	if (enable)
> > +		palmas_write(palmas, PALMAS_USB_OTG_BASE, PALMAS_USB_WAKEUP,
> > +			PALMAS_USB_WAKEUP_ID_WK_UP_COMP);
> > +	else
> > +		palmas_write(palmas, PALMAS_USB_OTG_BASE, PALMAS_USB_WAKEUP,
> 0);
> > +}
> > +
> > +static ssize_t palmas_usb_vbus_show(struct device *dev,
> > +			struct device_attribute *attr, char *buf)
> > +{
> > +	unsigned long		flags;
> > +	int			ret = -EINVAL;
> > +	struct palmas_usb	*palmas_usb = dev_get_drvdata(dev);
> > +
> > +	spin_lock_irqsave(&palmas_usb->lock, flags);
>
> This spinlock is used in this sysfs-show function only.
> Is this really needed?
> The only protected value here is "linkstat", which is "readonly"
> in this protected context.
> Thus, removing the spin_lock and updating like the following should
> be the same with less overhead:
>
> 	int linkstat = palmas_usb->linkstat;
> 	switch(linkstat) {

hmm.. ok.
> > +
> > +	switch (palmas_usb->linkstat) {
> > +	case PALMAS_USB_STATE_VBUS:
> > +	       ret = snprintf(buf, PAGE_SIZE, "vbus\n");
> > +	       break;
> > +	case PALMAS_USB_STATE_ID:
> > +	       ret = snprintf(buf, PAGE_SIZE, "id\n");
> > +	       break;
> > +	case PALMAS_USB_STATE_DISCONNECT:
> > +	       ret = snprintf(buf, PAGE_SIZE, "none\n");
> > +	       break;
> > +	default:
> > +	       ret = snprintf(buf, PAGE_SIZE, "UNKNOWN\n");
> > +	}
> > +	spin_unlock_irqrestore(&palmas_usb->lock, flags);
> > +
> > +	return ret;
> > +}
> > +static DEVICE_ATTR(vbus, 0444, palmas_usb_vbus_show, NULL);
> > +
>
> []
>
> > +
> > +static void palmas_set_vbus_work(struct work_struct *data)
> > +{
> > +	int ret;
> > +	struct palmas_usb *palmas_usb = container_of(data, struct
> palmas_usb,
> > +
> set_vbus_work);
> > +
> > +	if (IS_ERR_OR_NULL(palmas_usb->vbus_reg)) {
> > +		dev_err(palmas_usb->dev, "invalid regulator\n");
> > +		return;
> > +	}
> > +
> > +	/*
> > +	 * Start driving VBUS. Set OPA_MODE bit in CHARGERUSB_CTRL1
> > +	 * register. This enables boost mode.
> > +	 */
> > +
> > +	if (palmas_usb->vbus_enable) {
> > +		ret = regulator_enable(palmas_usb->vbus_reg);
> > +		if (ret)
> > +			dev_dbg(palmas_usb->dev, "regulator enable
> failed\n");
> > +	} else {
> > +		regulator_disable(palmas_usb->vbus_reg);
> > +	}
> > +}
> > +
> > +static int palmas_set_vbus(struct phy_companion *comparator, bool
> enabled)
> > +{
> > +	struct palmas_usb *palmas_usb = comparator_to_palmas(comparator);
> > +
> > +	palmas_usb->vbus_enable = enabled;
> > +	schedule_work(&palmas_usb->set_vbus_work);
> > +
> > +	return 0;
> > +}
> > +
> > +static int palmas_start_srp(struct phy_companion *comparator)
> > +{
> > +	struct palmas_usb *palmas_usb = comparator_to_palmas(comparator);
> > +
> > +	palmas_write(palmas_usb->palmas, PALMAS_USB_OTG_BASE,
> > +		PALMAS_USB_VBUS_CTRL_SET,
> PALMAS_USB_VBUS_CTRL_SET_VBUS_DISCHRG
> > +		| PALMAS_USB_VBUS_CTRL_SET_VBUS_IADP_SINK);
> > +	palmas_write(palmas_usb->palmas, PALMAS_USB_OTG_BASE,
> > +		PALMAS_USB_VBUS_CTRL_SET,
> > +		PALMAS_USB_VBUS_CTRL_SET_VBUS_CHRG_VSYS |
> > +		PALMAS_USB_VBUS_CTRL_SET_VBUS_IADP_SINK);
> > +
> > +	mdelay(100);
>
> Why not msleep()? It's long enough to consider sleep.
> Is this in an atomic context? (if so, 100msec seems even more awful)

I guess it shouldn't be called from atomic context. Actually srp hasn't 
been tested because the controller driver we use with palmas dont have 
the infrastructure yet.
> > +
> > +	palmas_write(palmas_usb->palmas, PALMAS_USB_OTG_BASE,
> > +		PALMAS_USB_VBUS_CTRL_CLR,
> > +		PALMAS_USB_VBUS_CTRL_SET_VBUS_CHRG_VSYS |
> > +		PALMAS_USB_VBUS_CTRL_SET_VBUS_CHRG_VSYS);
> > +
> > +	return 0;
> > +}
> > +
> > +static void palmas_dt_to_pdata(struct device_node *node,
> > +		struct palmas_usb_platform_data *pdata)
> > +{
> > +	pdata->no_control_vbus = of_property_read_bool(node,
> > +					"ti,no_control_vbus");
> > +	pdata->wakeup = of_property_read_bool(node, "ti,wakeup");
> > +}
> > +
> > +static int palmas_usb_probe(struct platform_device *pdev)
> > +{
>
> []
>
> > +	/* init spinlock for workqueue */
> > +	spin_lock_init(&palmas_usb->lock);
>
> []
>
> > +	/* init spinlock for workqueue */
> > +	spin_lock_init(&palmas_usb->lock);
>
> Why this lock is initialized again?

Will remove it.

Thanks
Kishon
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