ARM: OMAP: PRCM: add suspend prepare / finish support

PRCM chain handler needs to disable forwarding of interrupts during
suspend, because runtime PM is disabled and most of the drivers
are potentially not able to handle interrupts coming at this time.

This patch masks all the PRCM interrupt events if a PRCM interrupt
occurs during suspend, but does not ack them. Once suspend finish
is called, all the masked events will be re-enabled, which causes
immediate PRCM interrupt and handles the postponed event.

The suspend prepare and complete  callbacks will be called from
pm34xx.c / pm44xx.c files in the following patches.

The functions defined in this patch should eventually be moved to
suspend->prepare and suspend->finish driver hooks, once the PRCM
chain handler will be made as its own driver.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Cc: Kevin Hilman <khilman@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
[paul@pwsan.com: add kerneldoc, add omap_prcm_irq_setup.saved_mask, add fn
 ptrs for save_and_clear_irqen() and restore_irqen()]
Signed-off-by: Paul Walmsley <paul@pwsan.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/arch/arm/mach-omap2/prm2xxx_3xxx.c b/arch/arm/mach-omap2/prm2xxx_3xxx.c
index 177c3ddba788..58d9ce70e792 100644
--- a/arch/arm/mach-omap2/prm2xxx_3xxx.c
+++ b/arch/arm/mach-omap2/prm2xxx_3xxx.c
@@ -244,3 +244,40 @@ void omap3xxx_prm_ocp_barrier(void)
 {
 	omap2_prm_read_mod_reg(OCP_MOD, OMAP3_PRM_REVISION_OFFSET);
 }
+
+/**
+ * omap3xxx_prm_save_and_clear_irqen - save/clear PRM_IRQENABLE_MPU reg
+ * @saved_mask: ptr to a u32 array to save IRQENABLE bits
+ *
+ * Save the PRM_IRQENABLE_MPU register to @saved_mask.  @saved_mask
+ * must be allocated by the caller.  Intended to be used in the PRM
+ * interrupt handler suspend callback.  The OCP barrier is needed to
+ * ensure the write to disable PRM interrupts reaches the PRM before
+ * returning; otherwise, spurious interrupts might occur.  No return
+ * value.
+ */
+void omap3xxx_prm_save_and_clear_irqen(u32 *saved_mask)
+{
+	saved_mask[0] = omap2_prm_read_mod_reg(OCP_MOD,
+					       OMAP3_PRM_IRQENABLE_MPU_OFFSET);
+	omap2_prm_write_mod_reg(0, OCP_MOD, OMAP3_PRM_IRQENABLE_MPU_OFFSET);
+
+	/* OCP barrier */
+	omap2_prm_read_mod_reg(OCP_MOD, OMAP3_PRM_REVISION_OFFSET);
+}
+
+/**
+ * omap3xxx_prm_restore_irqen - set PRM_IRQENABLE_MPU register from args
+ * @saved_mask: ptr to a u32 array of IRQENABLE bits saved previously
+ *
+ * Restore the PRM_IRQENABLE_MPU register from @saved_mask.  Intended
+ * to be used in the PRM interrupt handler resume callback to restore
+ * values saved by omap3xxx_prm_save_and_clear_irqen().  No OCP
+ * barrier should be needed here; any pending PRM interrupts will fire
+ * once the writes reach the PRM.  No return value.
+ */
+void omap3xxx_prm_restore_irqen(u32 *saved_mask)
+{
+	omap2_prm_write_mod_reg(saved_mask[0], OCP_MOD,
+				OMAP3_PRM_IRQENABLE_MPU_OFFSET);
+}