MUSB: PM cleanup

Second pass over TUSB power related code:

  - Add new field in board-specific platform data, giving a nonzero floor to
    the amount of VBUS power that peripherals could draw; pass that to the
    platform code.

  - Implement the call letting gadget drivers say how much VBUS power their
    current configuration may draw, and use that to initialize appropriately
    (pure-peripheral vs OTG modes) on USB reset and disconnect.

  - Provide TUSB-specific hook into OTG transceiver logic to support that
    VBUS call; and _only_ change the VBUS usage through that call.

  - Remove obsolete comment and bitmask declarations.

On one board I measured 36 mA (at 5.1V) coming from VBUS not the battery
using the default gadget drivers in non-OTG TUSB configuration.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

drivers/usb/musb/musb_gadget.c

@@ -1513,6 +1513,15 @@ static int musb_gadget_vbus_draw(struct usb_gadget *gadget, unsigned mA)
 }
 #endif
 
+static int musb_gadget_vbus_draw(struct usb_gadget *gadget, unsigned mA)
+{
+	struct musb	*musb = gadget_to_musb(gadget);
+
+	if (!musb->xceiv.set_power)
+		return -EOPNOTSUPP;
+	return otg_set_power(&musb->xceiv, mA);
+}
+
 static int musb_gadget_pullup(struct usb_gadget *gadget, int is_on)
 {
 	struct musb	*musb = gadget_to_musb(gadget);
@@ -1537,7 +1546,7 @@ static const struct usb_gadget_ops musb_gadget_operations = {
 	.wakeup			= musb_gadget_wakeup,
 	.set_selfpowered	= musb_gadget_set_self_powered,
 	//.vbus_session		= musb_gadget_vbus_session,
-	//.vbus_draw		= musb_gadget_vbus_draw,
+	.vbus_draw		= musb_gadget_vbus_draw,
 	.pullup			= musb_gadget_pullup,
 };
 
@@ -1925,6 +1934,9 @@ void musb_g_disconnect(struct musb *pThis)
 {
 	DBG(3, "devctl %02x\n", musb_readb(pThis->pRegs, MGC_O_HDRC_DEVCTL));
 
+	/* don't draw vbus until new b-default session */
+	(void) musb_gadget_vbus_draw(&pThis->g, 0);
+
 	pThis->g.speed = USB_SPEED_UNKNOWN;
 	if (pThis->pGadgetDriver && pThis->pGadgetDriver->disconnect) {
 		spin_unlock(&pThis->Lock);
@@ -2002,4 +2014,8 @@ __acquires(pThis->Lock)
 		pThis->g.is_a_peripheral = 1;
 	} else
 		WARN_ON(1);
+
+	/* start with default limits on VBUS power draw */
+	(void) musb_gadget_vbus_draw(&pThis->g,
+			is_otg_enabled(pThis) ? 8 : 100);
 }

drivers/usb/musb/musbdefs.h

@@ -448,6 +448,8 @@ struct musb {
 
 	s8 bFailCode;		/* one of MUSB_ERR_* failure code */
 
+	u8			min_power;	/* vbus for periph, in mA/2 */
+
 	/* active means connected and not suspended */
 	unsigned is_active:1;
 

drivers/usb/musb/plat_uds.c

@@ -1601,6 +1601,7 @@ musb_init_controller(struct device *dev, int nIrq, void __iomem *ctrl)
 	spin_lock_init(&pThis->Lock);
 	pThis->board_mode = plat->mode;
 	pThis->board_set_power = plat->set_power;
+	pThis->min_power = plat->min_power;
 
 	/* assume vbus is off */
 

drivers/usb/musb/tusb6010.c

@@ -143,23 +143,36 @@ void musb_read_fifo(struct musb_hw_ep *hw_ep, u16 len, u8 *buf)
 	}
 }
 
-/*
- * Enables TUSB6010 to use VBUS as power source in peripheral mode.
- * In host mode, a local battery must power the TUSB chip as well as
- * (through the charge pump) VBUS.  For OTG peripherals, the battery
- * must power the chip until it enters a confguration that's allowed
- * to draw enough current (call it 100mA).
+/* This is used by gadget drivers, and OTG transceiver logic, allowing
+ * at most mA current to be drawn from VBUS during a Default-B session
+ * (that is, while VBUS exceeds 4.4V).  In Default-A (including pure host
+ * mode), or low power Default-B sessions, something else supplies power.
  */
-static inline void tusb_enable_vbus_charge(struct musb *musb)
+static int tusb_set_power(struct otg_transceiver *x, unsigned mA)
 {
+	struct musb	*musb = container_of(x, struct musb, xceiv);
 	void __iomem	*base = musb->ctrl_base;
 	u32		reg;
 
-	musb_writel(base, TUSB_PRCM_WAKEUP_MASK, 0xffff);
+	/* tps65030 seems to consume max 100mA, with maybe 60mA available
+	 * (measured on one board) for things other than tps and tusb.
+	 *
+	 * REVISIT we could use VBUS to supply only _one_ of { 1.5V, 3.3V }.
+	 * The actual current usage would be very board-specific.  For now,
+	 * it's simpler to just use an aggregate (also board-specific).
+	 */
+	if (x->default_a || mA < (musb->min_power << 1))
+		mA = 0;
+
 	reg = musb_readl(base, TUSB_PRCM_MNGMT);
-	reg &= ~TUSB_PRCM_MNGMT_SUSPEND_MASK;
-	reg |= TUSB_PRCM_MNGMT_CPEN_MASK;
+	if (mA)
+		reg |= TUSB_PRCM_MNGMT_15_SW_EN | TUSB_PRCM_MNGMT_33_SW_EN;
+	else
+		reg &= ~(TUSB_PRCM_MNGMT_15_SW_EN | TUSB_PRCM_MNGMT_33_SW_EN);
 	musb_writel(base, TUSB_PRCM_MNGMT, reg);
+
+	DBG(3, "draw max %d mA VBUS\n", mA);
+	return 0;
 }
 
 /* workaround for issue 13:  change clock during chip idle
@@ -184,7 +197,7 @@ void tusb_set_clock_source(struct musb *musb, int mode)
  * Idle TUSB6010 until next wake-up event; NOR access always wakes.
  * Other code ensures that we idle unless we're connected _and_ the
  * USB link is not suspended ... and tells us the relevant wakeup
- * events.
+ * events.  SW_EN for voltage is handled separately.
  */
 static void tusb_allow_idle(struct musb *musb, u32 wakeup_enables)
 {
@@ -197,9 +210,7 @@ static void tusb_allow_idle(struct musb *musb, u32 wakeup_enables)
 	musb_writel(base, TUSB_PRCM_WAKEUP_MASK, ~wakeup_enables);
 
 	reg = musb_readl(base, TUSB_PRCM_MNGMT);
-	reg &= ~( TUSB_PRCM_MNGMT_OTG_VBUS_DET_EN
-			| TUSB_PRCM_MNGMT_15_SW_EN
-			| TUSB_PRCM_MNGMT_33_SW_EN );
+	reg &= ~TUSB_PRCM_MNGMT_OTG_VBUS_DET_EN; /* REVISIT leave alone? */
 	reg |= TUSB_PRCM_MNGMT_OTG_SESS_END_EN
 			| TUSB_PRCM_MNGMT_PM_IDLE
 			| TUSB_PRCM_MNGMT_DEV_IDLE;
@@ -318,12 +329,6 @@ tusb_otg_ints(struct musb *musb, u32 int_src, void __iomem *base)
 		/* no vbus ~= disconnect */
 		if (!is_host_enabled(musb) || !musb->xceiv.default_a) {
 
-			/* REVISIT in B-Default state machine, use VBUS power
-			 * for the USB link when (a) non-OTG, since 100 mA is
-			 * always available; or (b) OTG after SET_CONFIGURATION
-			 * enabling 100+ (?) mA draw.
-			 */
-
 			/* REVISIT use the b_sess_valid comparator, not
 			 * lowpower one; TUSB_DEV_OTG_STAT_SESS_VALID ?
 			 */
@@ -671,6 +676,7 @@ int __devinit musb_platform_init(struct musb *musb)
 		return -ENODEV;
 	}
 	musb->isr = tusb_interrupt;
+	musb->xceiv.set_power = tusb_set_power;
 
 	setup_timer(&musb_idle_timer, musb_do_idle, (unsigned long) musb);
 

drivers/usb/musb/tusb6010.h

@@ -104,20 +104,6 @@
 #define		TUSB_PRCM_MNGMT_PM_IDLE			(1 << 1)
 #define		TUSB_PRCM_MNGMT_DEV_IDLE		(1 << 0)
 
-#define		TUSB_PRCM_MNGMT_PM_CLEAR_MASK	\
-			( TUSB_PRCM_MNGMT_15_SW_EN \
-			| TUSB_PRCM_MNGMT_33_SW_EN \
-			| TUSB_PRCM_MNGMT_PM_IDLE \
-			| TUSB_PRCM_MNGMT_DEV_IDLE )
-#define		TUSB_PRCM_MNGMT_CPEN_MASK	\
-			( TUSB_PRCM_MNGMT_OTG_VBUS_DET_EN \
-			| TUSB_PRCM_MNGMT_15_SW_EN \
-			| TUSB_PRCM_MNGMT_33_SW_EN )
-#define		TUSB_PRCM_MNGMT_SUSPEND_MASK	\
-			( TUSB_PRCM_MNGMT_OTG_SESS_END_EN \
-			| TUSB_PRCM_MNGMT_PM_IDLE \
-			| TUSB_PRCM_MNGMT_DEV_IDLE )
-
 /* Wake-up source clear and mask registers */
 #define TUSB_PRCM_WAKEUP_SOURCE		(TUSB_SYS_REG_BASE + 0x020)
 #define TUSB_PRCM_WAKEUP_CLEAR		(TUSB_SYS_REG_BASE + 0x028)

include/linux/usb/musb.h

@@ -27,6 +27,9 @@ struct musb_hdrc_platform_data {
 	/* (HOST or OTG) mA/2 power supplied on (default = 8mA) */
 	u8		power;
 
+	/* (PERIPHERAL) mA/2 max power consumed (default = 100mA) */
+	u8		min_power;
+
 	/* (HOST or OTG) msec/2 after VBUS on till power good */
 	u8		potpgt;