Re: [PATCH v4] extcon: Palmas Extcon Driver

[Kishon Vijay Abraham I <kishon@ti.com>]

Hi,

On Tuesday 07 May 2013 06:13 AM, myungjoo.ham wrote:
>> From: Graeme Gregory <gg@slimlogic.co.uk>
>>
>> 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@slimlogic.co.uk>
>> Signed-off-by: Moiz Sonasath <m-sonasath@ti.com>
>> Signed-off-by: Ruchika Kharwar <ruchika@ti.com>
>> Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
>> [kishon@ti.com: adapted palmas usb driver to use the extcon framework]
>> Signed-off-by: Sebastien Guiriec <s-guiriec@ti.com>
>
> 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