musb_hdrc: Add board specific external clock handling

On N800, if osc_ck is disabled by PM, USB will stop working.
Signed-off-by: Tony Lindgren <tony@atomide.com>

Updated so some of this code can be shared with other HDRC implementations;
pretty much everything except the TUSB 6010 EVM needs a clock.  This will
need more work in the future.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

arch/arm/mach-omap2/board-n800-usb.c

@@ -10,12 +10,14 @@
  */
 
 #include <linux/types.h>
-#include <linux/errno.h>
 #include <linux/delay.h>
 #include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/err.h>
 #include <linux/usb/musb.h>
 #include <asm/arch/gpmc.h>
 #include <asm/arch/gpio.h>
+#include <asm/arch/pm.h>
 
 #define TUSB_ASYNC_CS		1
 #define TUSB_SYNC_CS		4
@@ -23,6 +25,7 @@
 #define GPIO_TUSB_ENABLE	0
 
 static int tusb_set_power(int state);
+static int tusb_set_clock(struct clk *osc_ck, int state);
 
 #if	defined(CONFIG_USB_MUSB_OTG)
 #	define BOARD_MODE	MUSB_OTG
@@ -36,7 +39,9 @@ static struct musb_hdrc_platform_data tusb_data = {
 	.mode		= BOARD_MODE,
 	.multipoint	= 1,
 	.set_power	= tusb_set_power,
+	.set_clock	= tusb_set_clock,
 	.min_power	= 25,	/* x2 = 50 mA drawn from VBUS as peripheral */
+	.clock		= "osc_ck",
 };
 
 /*
@@ -71,6 +76,29 @@ static int tusb_set_power(int state)
 	return retval;
 }
 
+static int		osc_ck_on;
+
+static int tusb_set_clock(struct clk *osc_ck, int state)
+{
+	if (state) {
+		if (osc_ck_on > 0)
+			return -ENODEV;
+
+		omap2_block_sleep();
+		clk_enable(osc_ck);
+		osc_ck_on = 1;
+	} else {
+		if (osc_ck_on == 0)
+			return -ENODEV;
+
+		clk_disable(osc_ck);
+		osc_ck_on = 0;
+		omap2_allow_sleep();
+	}
+
+	return 0;
+}
+
 void __init n800_usb_init(void)
 {
 	int ret = 0;

drivers/usb/musb/musbdefs.h

@@ -39,6 +39,7 @@
 #include <linux/interrupt.h>
 #include <linux/smp_lock.h>
 #include <linux/errno.h>
+#include <linux/clk.h>
 #include <linux/device.h>
 #include <linux/usb/ch9.h>
 #include <linux/usb_gadget.h>
@@ -402,6 +403,8 @@ struct musb {
 	u8 board_mode;		/* enum musb_mode */
 	int			(*board_set_power)(int state);
 
+	int			(*set_clock)(struct clk *clk, int is_active);
+
 	u8			min_power;	/* vbus for periph, in mA/2 */
 
 	/* active means connected and not suspended */

drivers/usb/musb/plat_uds.c

@@ -97,7 +97,6 @@
 #include <linux/list.h>
 #include <linux/kobject.h>
 #include <linux/platform_device.h>
-#include <linux/clk.h>
 
 #include <asm/io.h>
 
@@ -792,6 +791,10 @@ static void musb_shutdown(struct platform_device *pdev)
 	spin_lock_irqsave(&musb->Lock, flags);
 	musb_platform_disable(musb);
 	musb_generic_disable(musb);
+	if (musb->clock) {
+		clk_put(musb->clock);
+		musb->clock = NULL;
+	}
 	spin_unlock_irqrestore(&musb->Lock, flags);
 
 	/* FIXME power down */
@@ -1712,8 +1715,23 @@ 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->set_clock = plat->set_clock;
 	pThis->min_power = plat->min_power;
 
+	/* Clock usage is chip-specific ... functional clock (DaVinci,
+	 * OMAP2430), or PHY ref (some TUSB6010 boards).  All this core
+	 * code does is make sure a clock handle is available; platform
+	 * code manages it during start/stop and suspend/resume.
+	 */
+	if (plat->clock) {
+		pThis->clock = clk_get(dev, plat->clock);
+		if (IS_ERR(pThis->clock)) {
+			status = PTR_ERR(pThis->clock);
+			pThis->clock = NULL;
+			goto fail;
+		}
+	}
+
 	/* assume vbus is off */
 
 	/* platform adjusts pThis->pRegs and pThis->isr if needed,
@@ -1825,6 +1843,8 @@ musb_init_controller(struct device *dev, int nIrq, void __iomem *ctrl)
 		musb_debug_create("driver/musb_hdrc", pThis);
 	else {
 fail:
+		if (pThis->clock)
+			clk_put(pThis->clock);
 		device_init_wakeup(dev, 0);
 		musb_free(pThis);
 		return status;

drivers/usb/musb/tusb6010.c

@@ -159,6 +159,9 @@ static int tusb_draw_power(struct otg_transceiver *x, unsigned mA)
 	/* tps65030 seems to consume max 100mA, with maybe 60mA available
 	 * (measured on one board) for things other than tps and tusb.
 	 *
+	 * Boards sharing the CPU clock with CLKIN will need to prevent
+	 * certain idle sleep states while the USB link is active.
+	 *
 	 * 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).
@@ -168,11 +171,15 @@ static int tusb_draw_power(struct otg_transceiver *x, unsigned mA)
 
 	reg = musb_readl(base, TUSB_PRCM_MNGMT);
 	if (mA) {
+		if (musb->set_clock)
+			musb->set_clock(musb->clock, 1);
 		musb->is_bus_powered = 1;
 		reg |= TUSB_PRCM_MNGMT_15_SW_EN | TUSB_PRCM_MNGMT_33_SW_EN;
 	} else {
 		musb->is_bus_powered = 0;
 		reg &= ~(TUSB_PRCM_MNGMT_15_SW_EN | TUSB_PRCM_MNGMT_33_SW_EN);
+		if (musb->set_clock)
+			musb->set_clock(musb->clock, 0);
 	}
 	musb_writel(base, TUSB_PRCM_MNGMT, reg);
 

include/linux/usb/musb.h

@@ -17,10 +17,15 @@ enum musb_mode {
 	MUSB_OTG		/* Mini-AB connector */
 };
 
+struct clk;
+
 struct musb_hdrc_platform_data {
 	/* MUSB_HOST, MUSB_PERIPHERAL, or MUSB_OTG */
 	u8		mode;
 
+	/* for clk_get() */
+	const char	*clock;
+
 	/* (HOST or OTG) switch VBUS on/off */
 	int		(*set_vbus)(struct device *dev, int is_on);
 
@@ -40,6 +45,9 @@ struct musb_hdrc_platform_data {
 
 	/* Power the device on or off */
 	int		(*set_power)(int state);
+
+	/* Turn device clock on or off */
+	int		(*set_clock)(struct clk *clock, int is_on);
 };