Re: [PATCH 1/3] usb: phy: Add RCAR Gen2 USB phy

From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: linux-sh@vger.kernel.org
Subject: Re: [PATCH 1/3] usb: phy: Add RCAR Gen2 USB phy
Date: Wed, 09 Oct 2013 20:32:12 +0000	[thread overview]
Message-ID: <1627679.QkRee4hVcu@avalon> (raw)
In-Reply-To: <1381188423-1867-2-git-send-email-valentine.barshak@cogentembedded.com>

Hi Valentine,

Thank you for the patch.

On Tuesday 08 October 2013 23:43:25 Valentine Barshak wrote:
> This adds RCAR Gen2 USB phy support. The driver configures
> USB channels 0/2 which are shared between PCI USB hosts and
> USBHS/USBSS devices. It also controls internal USBHS phy.
> 
> Signed-off-by: Valentine Barshak <valentine.barshak@cogentembedded.com>
> ---
>  drivers/usb/phy/Kconfig                         |  13 ++
>  drivers/usb/phy/Makefile                        |   1 +
>  drivers/usb/phy/phy-rcar-gen2-usb.c             | 255 +++++++++++++++++++++
>  include/linux/platform_data/usb-rcar-gen2-phy.h |  22 ++
>  4 files changed, 291 insertions(+)
>  create mode 100644 drivers/usb/phy/phy-rcar-gen2-usb.c
>  create mode 100644 include/linux/platform_data/usb-rcar-gen2-phy.h
> 
> diff --git a/drivers/usb/phy/Kconfig b/drivers/usb/phy/Kconfig
> index d5589f9..297062c 100644
> --- a/drivers/usb/phy/Kconfig
> +++ b/drivers/usb/phy/Kconfig
> @@ -214,6 +214,19 @@ config USB_RCAR_PHY
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called phy-rcar-usb.
> 
> +config USB_RCAR_GEN2_PHY
> +	tristate "Renesas R-Car Gen2 USB PHY support"
> +	depends on ARCH_R8A7790 || ARCH_R8A7791

From a development point of view it's always nice to be able to compile the 
driver for a wider range of devices, even if the device is only found in the 
R8A779[01]. This allows catching compilation errors, for instance caused by 
API changes that affect all drivers using the API being modified.

I would use either

	depends on ARM

or

	depends on ARCH_R8A7790 || ARCH_R8A7791 || COMPILE_TEST

(assuming the driver can compile on non-ARM platforms, otherwise the above 
line could be changed to ARCH_R8A7790 || ARCH_R8A7791 || (ARM && 
COMPILE_TEST)).

> +	select USB_PHY
> +	help
> +	  Say Y here to add support for the Renesas R-Car Gen2 USB PHY driver.
> +	  It is typically used to control internal USB PHY for USBHS,
> +	  and to configure shared USB channels 0 and 2.
> +	  This driver supports R8A7790 and R8A7791.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called phy-rcar-gen2-usb.
> +
>  config USB_ULPI
>  	bool "Generic ULPI Transceiver Driver"
>  	depends on ARM
> diff --git a/drivers/usb/phy/Makefile b/drivers/usb/phy/Makefile
> index 2135e85..8c5b147 100644
> --- a/drivers/usb/phy/Makefile
> +++ b/drivers/usb/phy/Makefile
> @@ -29,5 +29,6 @@ obj-$(CONFIG_USB_MSM_OTG)		+= phy-msm-usb.o
>  obj-$(CONFIG_USB_MV_OTG)		+= phy-mv-usb.o
>  obj-$(CONFIG_USB_MXS_PHY)		+= phy-mxs-usb.o
>  obj-$(CONFIG_USB_RCAR_PHY)		+= phy-rcar-usb.o
> +obj-$(CONFIG_USB_RCAR_GEN2_PHY)		+= phy-rcar-gen2-usb.o
>  obj-$(CONFIG_USB_ULPI)			+= phy-ulpi.o
>  obj-$(CONFIG_USB_ULPI_VIEWPORT)		+= phy-ulpi-viewport.o
> diff --git a/drivers/usb/phy/phy-rcar-gen2-usb.c
> b/drivers/usb/phy/phy-rcar-gen2-usb.c new file mode 100644
> index 0000000..a2e6f9f
> --- /dev/null
> +++ b/drivers/usb/phy/phy-rcar-gen2-usb.c
> @@ -0,0 +1,255 @@
> +/*
> + * Renesas R-Car Gen2 USB phy driver
> + *
> + * Copyright (C) 2013 Renesas Solutions Corp.
> + * Copyright (C) 2013 Cogent Embedded, Inc.
> + *
> + * 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/clk.h>
> +#include <linux/delay.h>
> +#include <linux/io.h>
> +#include <linux/usb/otg.h>
> +#include <linux/platform_data/usb-rcar-gen2-phy.h>
> +#include <linux/platform_device.h>
> +#include <linux/spinlock.h>
> +#include <linux/module.h>

Would you mind ordering the headers alphabetically ? This helps avoiding 
duplicate includes, an existing include might not be noticed at first glance 
when adding a new one if the list is long and not sorted.

> +struct rcar_gen2_usb_phy_priv {
> +	struct usb_phy phy;
> +	void __iomem *base;
> +	struct clk *clk;
> +	spinlock_t lock;
> +	int usecount;
> +	u32 ugctrl2;
> +};
> +
> +#define usb_phy_to_priv(p) container_of(p, struct rcar_gen2_usb_phy_priv,
> phy) +
> +/* Low Power Status register */
> +#define USBHS_LPSTS_REG			0x02
> +#define USBHS_LPSTS_SUSPM		(1 << 14)
> +
> +/* USB General control register */
> +#define USBHS_UGCTRL_REG		0x80
> +#define USBHS_UGCTRL_CONNECT		(1 << 2)
> +#define USBHS_UGCTRL_PLLRESET		(1 << 0)
> +
> +/* USB General control register 2 */
> +#define USBHS_UGCTRL2_REG		0x84
> +#define USBHS_UGCTRL2_USB0_PCI		(1 << 4)
> +#define USBHS_UGCTRL2_USB0_HS		(3 << 4)
> +#define USBHS_UGCTRL2_USB2_PCI		(0 << 31)
> +#define USBHS_UGCTRL2_USB2_SS		(1 << 31)
> +
> +/* USB General status register */
> +#define USBHS_UGSTS_REG			0x88
> +#define USBHS_UGSTS_LOCK		(3 << 8)
> +
> +/* Enable USBHS internal phy */
> +static int __rcar_gen2_usbhs_phy_enable(void __iomem *base)

Any reason for the __ as a function prefix ?

I would have passed a struct rcar_gen2_usb_phy_priv pointer to this function, 
which would allow you to print a debugging message using dev_dbg() in case of 
a timeout. That's up to you.

> +{
> +	u32 val;
> +	int i;

I tend to use unsigned int for loop counters that can't take negative values.

> +
> +	/* USBHS PHY power on */
> +	val = ioread32(base + USBHS_UGCTRL_REG);
> +	val &= ~USBHS_UGCTRL_PLLRESET;
> +	iowrite32(val, base + USBHS_UGCTRL_REG);
> +
> +	val = ioread16(base + USBHS_LPSTS_REG);
> +	val |= USBHS_LPSTS_SUSPM;
> +	iowrite16(val, base + USBHS_LPSTS_REG);
> +
> +	for (i = 0; i < 20; i++) {
> +		val = ioread32(base + USBHS_UGSTS_REG);
> +		if ((val & USBHS_UGSTS_LOCK) = USBHS_UGSTS_LOCK) {
> +			val = ioread32(base + USBHS_UGCTRL_REG);
> +			val |= USBHS_UGCTRL_CONNECT;
> +			iowrite32(val, base + USBHS_UGCTRL_REG);
> +			return 0;
> +		}
> +		udelay(1);

What's the maximum number of iterations you've observed in practice ? Does the 
20 limit come from somewhere in particular ?

> +	}
> +
> +	/* Timed out waiting for the PLL lock */
> +	return -ETIMEDOUT;
> +}
> +
> +/* Disable USBHS internal phy */
> +static int __rcar_gen2_usbhs_phy_disable(void __iomem *base)
> +{
> +	u32 val;
> +
> +	/* USBHS PHY power off */
> +	val = ioread32(base + USBHS_UGCTRL_REG);
> +	val &= ~USBHS_UGCTRL_CONNECT;
> +	iowrite32(val, base + USBHS_UGCTRL_REG);
> +
> +	val = ioread16(base + USBHS_LPSTS_REG);
> +	val &= ~USBHS_LPSTS_SUSPM;
> +	iowrite16(val, base + USBHS_LPSTS_REG);
> +
> +	val = ioread32(base + USBHS_UGCTRL_REG);
> +	val |= USBHS_UGCTRL_PLLRESET;
> +	iowrite32(val, base + USBHS_UGCTRL_REG);
> +	return 0;
> +}
> +
> +/* Setup USB channels */
> +static void __rcar_gen2_usb_phy_init(struct rcar_gen2_usb_phy_priv *priv)
> +{
> +	u32 val;
> +
> +	clk_prepare_enable(priv->clk);
> +
> +	/* Set USB channels in the USBHS UGCTRL2 register */
> +	val = ioread32(priv->base);
> +	val &= ~(USBHS_UGCTRL2_USB0_HS | USBHS_UGCTRL2_USB2_SS);
> +	val |= priv->ugctrl2;
> +	iowrite32(val, priv->base);
> +}
> +
> +/* Shutdown USB channels */
> +static void __rcar_gen2_usb_phy_shutdown(struct rcar_gen2_usb_phy_priv
> *priv)
> +{
> +	__rcar_gen2_usbhs_phy_disable(priv->base);
> +	clk_disable_unprepare(priv->clk);
> +}
> +
> +static int rcar_gen2_usb_phy_set_suspend(struct usb_phy *phy, int suspend)
> +{
> +	struct rcar_gen2_usb_phy_priv *priv = usb_phy_to_priv(phy);
> +	unsigned long flags;
> +	int retval;
> +
> +	spin_lock_irqsave(&priv->lock, flags);
> +	retval = suspend ? __rcar_gen2_usbhs_phy_disable(priv->base) :
> +			   __rcar_gen2_usbhs_phy_enable(priv->base);
> +	spin_unlock_irqrestore(&priv->lock, flags);
> +	return retval;
> +}
> +
> +static int rcar_gen2_usb_phy_init(struct usb_phy *phy)
> +{
> +	struct rcar_gen2_usb_phy_priv *priv = usb_phy_to_priv(phy);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&priv->lock, flags);
> +	/*
> +	 * Enable the clock and setup USB channels
> +	 * if it's the first user
> +	 */
> +	if (!priv->usecount++)
> +		__rcar_gen2_usb_phy_init(priv);
> +	spin_unlock_irqrestore(&priv->lock, flags);
> +	return 0;
> +}
> +
> +static void rcar_gen2_usb_phy_shutdown(struct usb_phy *phy)
> +{
> +	struct rcar_gen2_usb_phy_priv *priv = usb_phy_to_priv(phy);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&priv->lock, flags);
> +	if (!priv->usecount) {
> +		dev_warn(phy->dev, "Trying to disable phy with 0 usecount\n");
> +		goto out;
> +	}
> +
> +	/* Disable everything if it's the last user */
> +	if (!--priv->usecount)
> +		__rcar_gen2_usb_phy_shutdown(priv);
> +out:
> +	spin_unlock_irqrestore(&priv->lock, flags);
> +}
> +
> +static int rcar_gen2_usb_phy_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct rcar_gen2_phy_platform_data *pdata;
> +	struct rcar_gen2_usb_phy_priv *priv;
> +	struct resource *res;
> +	void __iomem *base;
> +	struct clk *clk;
> +	int retval;
> +
> +	pdata = dev_get_platdata(&pdev->dev);

DT support would be nice too :-)

> +	if (!pdata) {
> +		dev_err(dev, "No platform data\n");
> +		return -EINVAL;
> +	}
> +
> +	clk = devm_clk_get(&pdev->dev, "usbhs");
> +	if (IS_ERR(clk)) {
> +		dev_err(&pdev->dev, "Can't get the clock\n");
> +		return PTR_ERR(clk);
> +	}
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res) {
> +		dev_err(dev, "No memory resource\n");

No need to check the return value or print an error message, 
devm_ioremap_resource() already takes care of that.

> +		return -ENODEV;
> +	}
> +
> +	base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(base)) {
> +		dev_err(dev, "Failed to ioremap resource\n");

No need to print an error message here either.

> +		return PTR_ERR(base);
> +	}
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv) {
> +		dev_err(dev, "Memory allocation failed\n");
> +		return -ENOMEM;
> +	}
> +
> +	spin_lock_init(&priv->lock);
> +	priv->clk = clk;
> +	priv->base = base;
> +	priv->ugctrl2 = pdata->chan0_pci ?
> +			USBHS_UGCTRL2_USB0_PCI : USBHS_UGCTRL2_USB0_HS;
> +	priv->ugctrl2 |= pdata->chan2_pci ?
> +			USBHS_UGCTRL2_USB2_PCI : USBHS_UGCTRL2_USB2_SS;
> +	priv->phy.dev = dev;
> +	priv->phy.label = dev_name(dev);
> +	priv->phy.init = rcar_gen2_usb_phy_init;
> +	priv->phy.shutdown = rcar_gen2_usb_phy_shutdown;
> +	priv->phy.set_suspend = rcar_gen2_usb_phy_set_suspend;
> +
> +	retval = usb_add_phy(&priv->phy, USB_PHY_TYPE_USB2);
> +	if (retval < 0) {
> +		dev_err(dev, "Failed to add USB phy\n");
> +		return retval;
> +	}
> +
> +	platform_set_drvdata(pdev, priv);
> +
> +	return retval;
> +}
> +
> +static int rcar_gen2_usb_phy_remove(struct platform_device *pdev)
> +{
> +	struct rcar_gen2_usb_phy_priv *priv = platform_get_drvdata(pdev);
> +
> +	usb_remove_phy(&priv->phy);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver rcar_gen2_usb_phy_driver = {
> +	.driver = {
> +		.name = "usb_phy_rcar_gen2",
> +	},
> +	.probe = rcar_gen2_usb_phy_probe,
> +	.remove = rcar_gen2_usb_phy_remove,
> +};
> +
> +module_platform_driver(rcar_gen2_usb_phy_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("Renesas R-Car Gen2 USB phy");
> +MODULE_AUTHOR("Valentine Barshak <valentine.barshak@cogentembedded.com>");
> diff --git a/include/linux/platform_data/usb-rcar-gen2-phy.h
> b/include/linux/platform_data/usb-rcar-gen2-phy.h new file mode 100644
> index 0000000..dd3ba46
> --- /dev/null
> +++ b/include/linux/platform_data/usb-rcar-gen2-phy.h
> @@ -0,0 +1,22 @@
> +/*
> + * Copyright (C) 2013 Renesas Solutions Corp.
> + * Copyright (C) 2013 Cogent Embedded, Inc.
> + *
> + * 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 __USB_RCAR_GEN2_PHY_H
> +#define __USB_RCAR_GEN2_PHY_H
> +
> +#include <linux/types.h>
> +
> +struct rcar_gen2_phy_platform_data {
> +	/* USB channel 0 configuration */
> +	bool chan0_pci:1;	/* true: PCI USB host 0, false: USBHS */
> +	/* USB channel 2 configuration */
> +	bool chan2_pci:1;	/* true: PCI USB host 2, false: USBSS */
> +};
> +
> +#endif
-- 
Regards,

Laurent Pinchart