RE: [PATCH v3 1/2] usb: ohci-at91: Forcibly suspend ports while USB suspend

["Yang, Wenyou" <Wenyou.Yang@atmel.com>]

Hi Rob,

> -----Original Message-----
> From: Rob Herring [mailto:robh@kernel.org]
> Sent: 2016年6月9日 4:27
> To: Yang, Wenyou <Wenyou.Yang@atmel.com>
> Cc: Alan Stern <stern@rowland.harvard.edu>; Greg Kroah-Hartman
> <gregkh@linuxfoundation.org>; Ferre, Nicolas <Nicolas.FERRE@atmel.com>;
> Pawel Moll <pawel.moll@arm.com>; Mark Brown <broonie@kernel.org>; Ian
> Campbell <ijc+devicetree@hellion.org.uk>; Kumar Gala <galak@codeaurora.org>;
> Alexandre Belloni <alexandre.belloni@free-electrons.com>; linux-
> kernel@vger.kernel.org; devicetree@vger.kernel.org; linux-arm-
> kernel@lists.infradead.org; linux-usb@vger.kernel.org
> Subject: Re: [PATCH v3 1/2] usb: ohci-at91: Forcibly suspend ports while USB
> suspend
> 
> On Wed, Jun 08, 2016 at 12:15:10PM +0800, Wenyou Yang wrote:
> > In order to the save power consumption, as a workaround, suspend
> > forcibly the USB PORTA/B/C via set the SUSPEND_A/B/C bits of OHCI
> > Interrupt Configuration Register in the SFRs while OHCI USB suspend.
> >
> > This suspend operation must be done before the USB clock is disabled,
> > resume after the USB clock is enabled.
> >
> > Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
> > ---
> >
> > Changes in v3:
> >  - Change the compatible description for more precise.
> >
> > Changes in v2:
> >  - Add compatible to support forcibly suspend the ports.
> >  - Add soc/at91/at91_sfr.h to accommodate the defines.
> >  - Add error checking for .sfr_regmap.
> >  - Remove unnecessary regmap_read() statement.
> >
> >  .../devicetree/bindings/usb/atmel-usb.txt          |  6 +-
> >  drivers/usb/host/ohci-at91.c                       | 80 +++++++++++++++++++++-
> >  include/soc/at91/at91_sfr.h                        | 29 ++++++++
> >  3 files changed, 112 insertions(+), 3 deletions(-)  create mode
> > 100644 include/soc/at91/at91_sfr.h
> >
> > diff --git a/Documentation/devicetree/bindings/usb/atmel-usb.txt
> > b/Documentation/devicetree/bindings/usb/atmel-usb.txt
> > index 5883b73..888deaa 100644
> > --- a/Documentation/devicetree/bindings/usb/atmel-usb.txt
> > +++ b/Documentation/devicetree/bindings/usb/atmel-usb.txt
> > @@ -3,8 +3,10 @@ Atmel SOC USB controllers  OHCI
> >
> >  Required properties:
> > - - compatible: Should be "atmel,at91rm9200-ohci" for USB controllers
> > -   used in host mode.
> > + - compatible: Should be one of the following
> > +	       "atmel,at91rm9200-ohci" for USB controllers used in host mode.
> > +	       "atmel,sama5d2-ohci" for USB controllers used in host mode
> > +	       on SAMA5D2 which can force to suspend.
> 
> Guess I wasn't clear enough before. Drop "which can force to suspend".

In previous mail, Nicolas gave a suggestion with "...on SAMA5D2 and compatible SoCs that must explicitly force suspend through the Special Function Register (SFR)."

I think it is more clear, what is your opinion?

> 
> >   - reg: Address and length of the register set for the device
> >   - interrupts: Should contain ehci interrupt
> >   - clocks: Should reference the peripheral, host and system clocks
> > diff --git a/drivers/usb/host/ohci-at91.c
> > b/drivers/usb/host/ohci-at91.c index d177372..54e8feb 100644
> > --- a/drivers/usb/host/ohci-at91.c
> > +++ b/drivers/usb/host/ohci-at91.c
> > @@ -21,8 +21,11 @@
> >  #include <linux/io.h>
> >  #include <linux/kernel.h>
> >  #include <linux/module.h>
> > +#include <linux/mfd/syscon.h>
> > +#include <linux/regmap.h>
> >  #include <linux/usb.h>
> >  #include <linux/usb/hcd.h>
> > +#include <soc/at91/at91_sfr.h>
> >
> >  #include "ohci.h"
> >
> > @@ -45,12 +48,18 @@ struct at91_usbh_data {
> >  	u8 overcurrent_changed[AT91_MAX_USBH_PORTS];
> >  };
> >
> > +struct ohci_at91_caps {
> > +	bool suspend_ctrl;
> > +};
> > +
> >  struct ohci_at91_priv {
> >  	struct clk *iclk;
> >  	struct clk *fclk;
> >  	struct clk *hclk;
> >  	bool clocked;
> >  	bool wakeup;		/* Saved wake-up state for resume */
> > +	const struct ohci_at91_caps *caps;
> > +	struct regmap *sfr_regmap;
> >  };
> >  /* interface and function clocks; sometimes also an AHB clock */
> >
> > @@ -132,6 +141,17 @@ static void at91_stop_hc(struct platform_device
> > *pdev)
> >
> >
> > /*--------------------------------------------------------------------
> > -----*/
> >
> > +struct regmap *at91_dt_syscon_sfr(void) {
> > +	struct regmap *regmap;
> > +
> > +	regmap = syscon_regmap_lookup_by_compatible("atmel,sama5d2-sfr");
> > +	if (IS_ERR(regmap))
> > +		regmap = NULL;
> > +
> > +	return regmap;
> > +}
> > +
> >  static void usb_hcd_at91_remove (struct usb_hcd *, struct
> > platform_device *);
> >
> >  /* configure so an HC device and id are always provided */ @@ -197,6
> > +217,17 @@ static int usb_hcd_at91_probe(const struct hc_driver *driver,
> >  		goto err;
> >  	}
> >
> > +	ohci_at91->caps = (const struct ohci_at91_caps *)
> > +			  of_device_get_match_data(&pdev->dev);
> > +	if (!ohci_at91->caps)
> > +		return -ENODEV;
> > +
> > +	if (ohci_at91->caps->suspend_ctrl) {
> > +		ohci_at91->sfr_regmap = at91_dt_syscon_sfr();
> > +		if (!ohci_at91->sfr_regmap)
> > +			dev_warn(dev, "failed to find sfr node\n");
> > +	}
> > +
> >  	board = hcd->self.controller->platform_data;
> >  	ohci = hcd_to_ohci(hcd);
> >  	ohci->num_ports = board->ports;
> > @@ -440,8 +471,17 @@ static irqreturn_t ohci_hcd_at91_overcurrent_irq(int
> irq, void *data)
> >  	return IRQ_HANDLED;
> >  }
> >
> > +static const struct ohci_at91_caps at91rm9200_caps = {
> > +	.suspend_ctrl = false,
> > +};
> > +
> > +static const struct ohci_at91_caps sama5d2_caps = {
> > +	.suspend_ctrl = true,
> > +};
> > +
> >  static const struct of_device_id at91_ohci_dt_ids[] = {
> > -	{ .compatible = "atmel,at91rm9200-ohci" },
> > +	{ .compatible = "atmel,at91rm9200-ohci", .data = &at91rm9200_caps },
> > +	{ .compatible = "atmel,sama5d2-ohci", .data = &sama5d2_caps },
> >  	{ /* sentinel */ }
> >  };
> >
> > @@ -581,6 +621,38 @@ static int ohci_hcd_at91_drv_remove(struct
> platform_device *pdev)
> >  	return 0;
> >  }
> >
> > +static int ohci_at91_port_ctrl(struct regmap *regmap, bool enable) {
> > +	u32 regval;
> > +	int ret;
> > +
> > +	if (!regmap)
> > +		return -EINVAL;
> > +
> > +	ret = regmap_read(regmap, SFR_OHCIICR, &regval);
> > +	if (ret)
> > +		return ret;
> > +
> > +	if (enable)
> > +		regval &= ~SFR_OHCIICR_USB_SUSPEND;
> > +	else
> > +		regval |= SFR_OHCIICR_USB_SUSPEND;
> > +
> > +	regmap_write(regmap, SFR_OHCIICR, regval);
> > +
> > +	return 0;
> > +}
> > +
> > +static int ohci_at91_port_suspend(struct regmap *regmap) {
> > +	return ohci_at91_port_ctrl(regmap, false); }
> > +
> > +static int ohci_at91_port_resume(struct regmap *regmap) {
> > +	return ohci_at91_port_ctrl(regmap, true); }
> > +
> >  static int __maybe_unused
> >  ohci_hcd_at91_drv_suspend(struct device *dev)  { @@ -618,6 +690,9 @@
> > ohci_hcd_at91_drv_suspend(struct device *dev)
> >  		ohci_writel(ohci, ohci->hc_control, &ohci->regs->control);
> >  		ohci->rh_state = OHCI_RH_HALTED;
> >
> > +		if (ohci_at91->caps->suspend_ctrl)
> > +			ohci_at91_port_suspend(ohci_at91->sfr_regmap);
> > +
> >  		/* flush the writes */
> >  		(void) ohci_readl (ohci, &ohci->regs->control);
> >  		at91_stop_clock(ohci_at91);
> > @@ -637,6 +712,9 @@ ohci_hcd_at91_drv_resume(struct device *dev)
> >
> >  	at91_start_clock(ohci_at91);
> >
> > +	if (ohci_at91->caps->suspend_ctrl)
> > +		ohci_at91_port_resume(ohci_at91->sfr_regmap);
> > +
> >  	ohci_resume(hcd, false);
> >  	return 0;
> >  }
> > diff --git a/include/soc/at91/at91_sfr.h b/include/soc/at91/at91_sfr.h
> > new file mode 100644 index 0000000..04a3a1e
> > --- /dev/null
> > +++ b/include/soc/at91/at91_sfr.h
> > @@ -0,0 +1,29 @@
> > +/*
> > + * Header file for the Atmel DDR/SDR SDRAM Controller
> > + *
> > + * Copyright (C) 2016 Atmel Corporation
> > + *
> > + * Author: Wenyou Yang <wenyou.yang@atmel.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.
> > + *
> > + */
> > +#ifndef __AT91_SFR_H__
> > +#define __AT91_SFR_H__
> > +
> > +#define SFR_DDRCFG		0x04	/* DDR Configuration Register */
> > +/* 0x08 ~ 0x0c: Reserved */
> > +#define SFR_OHCIICR		0x10	/* OHCI Interrupt Configuration
> Register */
> > +#define SFR_OHCIISR		0x14	/* OHCI Interrupt Status Register
> */
> > +
> > +#define SFR_OHCIICR_SUSPEND_A	BIT(8)
> > +#define SFR_OHCIICR_SUSPEND_B	BIT(9)
> > +#define SFR_OHCIICR_SUSPEND_C	BIT(10)
> > +
> > +#define SFR_OHCIICR_USB_SUSPEND	(SFR_OHCIICR_SUSPEND_A | \
> > +				 SFR_OHCIICR_SUSPEND_B | \
> > +				 SFR_OHCIICR_SUSPEND_C)
> > +
> > +#endif
> > --
> > 2.7.4
> >


Best Regards,
Wenyou Yang