ARM: OMAP4: PRM: Add IO Daisychain support

IO daisychain is a mechanism that allows individual IO pads to generate
wakeup events on their own based on a switch of an input signal level.
This allows the hardware module behind the pad to be powered down, but
still have device level capability to detect IO events, and once this
happens the module can be powered back up to resume IO. See section
3.9.4 in OMAP4430 Public TRM for details.

Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Signed-off-by: Vishwanath BS <vishwanath.bs@ti.com>
Signed-off-by: Tero Kristo <t-kristo@ti.com>
[paul@pwsan.com: use the shared MAX_IOPAD_LATCH_TIME declaration; renamed
 omap4_trigger_io_chain() to conform to other PRM function names;
 added kerneldoc; resolved checkpatch warnings]
Signed-off-by: Paul Walmsley <paul@pwsan.com>

arch/arm/mach-omap2/prm44xx.c

@@ -233,6 +233,60 @@ void omap44xx_prm_restore_irqen(u32 *saved_mask)
 				 OMAP4_PRM_IRQENABLE_MPU_2_OFFSET);
 }
 
+/**
+ * omap44xx_prm_reconfigure_io_chain - clear latches and reconfigure I/O chain
+ *
+ * Clear any previously-latched I/O wakeup events and ensure that the
+ * I/O wakeup gates are aligned with the current mux settings.  Works
+ * by asserting WUCLKIN, waiting for WUCLKOUT to be asserted, and then
+ * deasserting WUCLKIN and waiting for WUCLKOUT to be deasserted.
+ * No return value. XXX Are the final two steps necessary?
+ */
+void omap44xx_prm_reconfigure_io_chain(void)
+{
+	int i = 0;
+	u32 v;
+
+	v = omap4_prm_read_inst_reg(OMAP4430_PRM_DEVICE_INST,
+				    OMAP4_PRM_IO_PMCTRL_OFFSET);
+
+	/* Enable GLOBAL_WUEN */
+	if (!(v & OMAP4430_GLOBAL_WUEN_MASK))
+		omap4_prm_rmw_inst_reg_bits(OMAP4430_GLOBAL_WUEN_MASK,
+					    OMAP4430_GLOBAL_WUEN_MASK,
+					    OMAP4430_PRM_DEVICE_INST,
+					    OMAP4_PRM_IO_PMCTRL_OFFSET);
+
+	/* Trigger WUCLKIN enable */
+	omap4_prm_rmw_inst_reg_bits(OMAP4430_WUCLK_CTRL_MASK,
+				    OMAP4430_WUCLK_CTRL_MASK,
+				    OMAP4430_PRM_DEVICE_INST,
+				    OMAP4_PRM_IO_PMCTRL_OFFSET);
+	omap_test_timeout(
+		(((omap4_prm_read_inst_reg(OMAP4430_PRM_DEVICE_INST,
+					   OMAP4_PRM_IO_PMCTRL_OFFSET) &
+		   OMAP4430_WUCLK_STATUS_MASK) >>
+		  OMAP4430_WUCLK_STATUS_SHIFT) == 1),
+		MAX_IOPAD_LATCH_TIME, i);
+	if (i == MAX_IOPAD_LATCH_TIME)
+		pr_warn("PRM: I/O chain clock line assertion timed out\n");
+
+	/* Trigger WUCLKIN disable */
+	omap4_prm_rmw_inst_reg_bits(OMAP4430_WUCLK_CTRL_MASK, 0x0,
+				    OMAP4430_PRM_DEVICE_INST,
+				    OMAP4_PRM_IO_PMCTRL_OFFSET);
+	omap_test_timeout(
+		(((omap4_prm_read_inst_reg(OMAP4430_PRM_DEVICE_INST,
+					   OMAP4_PRM_IO_PMCTRL_OFFSET) &
+		   OMAP4430_WUCLK_STATUS_MASK) >>
+		  OMAP4430_WUCLK_STATUS_SHIFT) == 0),
+		MAX_IOPAD_LATCH_TIME, i);
+	if (i == MAX_IOPAD_LATCH_TIME)
+		pr_warn("PRM: I/O chain clock line deassertion timed out\n");
+
+	return;
+}
+
 static int __init omap4xxx_prcm_init(void)
 {
 	if (cpu_is_omap44xx())

arch/arm/mach-omap2/prm44xx.h

@@ -763,6 +763,8 @@ extern u32 omap4_prm_vcvp_read(u8 offset);
 extern void omap4_prm_vcvp_write(u32 val, u8 offset);
 extern u32 omap4_prm_vcvp_rmw(u32 mask, u32 bits, u8 offset);
 
+extern void omap44xx_prm_reconfigure_io_chain(void);
+
 /* PRM interrupt-related functions */
 extern void omap44xx_prm_read_pending_irqs(unsigned long *events);
 extern void omap44xx_prm_ocp_barrier(void);