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Message-id: <005c01ce4abb$d956fea0$8c04fbe0$@samsung.com>
Date: Tue, 07 May 2013 09:43:10 +0900
From: "myungjoo.ham" <myungjoo.ham@...sung.com>
To: 'Kishon Vijay Abraham I' <kishon@...com>, cw00.choi@...sung.com,
balbi@...com, ldewangan@...dia.com,
devicetree-discuss@...ts.ozlabs.org, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: grant.likely@...aro.org, rob.herring@...xeda.com, rob@...dley.net,
gg@...mlogic.co.uk, ruchika@...com, tony@...mide.com,
sameo@...ux.intel.com, broonie@...nsource.wolfsonmicro.com
Subject: RE: [PATCH v4] extcon: Palmas Extcon Driver
> From: Graeme Gregory <gg@...mlogic.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@...mlogic.co.uk>
> Signed-off-by: Moiz Sonasath <m-sonasath@...com>
> Signed-off-by: Ruchika Kharwar <ruchika@...com>
> Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
> [kishon@...com: adapted palmas usb driver to use the extcon framework]
> Signed-off-by: Sebastien Guiriec <s-guiriec@...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)
> +
> +#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) {
> +
> + 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)
> +
> + 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?
> +
> + INIT_WORK(&palmas_usb->set_vbus_work, palmas_set_vbus_work);
> +
[]
> +
> +module_platform_driver(palmas_usb_driver);
> +
> +MODULE_ALIAS("platform:palmas-usb");
> +MODULE_AUTHOR("Graeme Gregory <gg@...mlogic.co.uk>");
Is this intentional?
> +MODULE_DESCRIPTION("Palmas USB transceiver driver");
> +MODULE_LICENSE("GPL");
> +MODULE_DEVICE_TABLE(of, of_palmas_match_tbl);
>
Cheers,
MyungJoo
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