usb: ohci-at91: Forcibly suspend ports while USB suspend

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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.
  - 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

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;
 }

include/soc/at91/at91_sfr.h

+/*
+ * 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