+#ifdef CONFIG_MTD_XIP
+
+/*
+ * No interrupt what so ever can be serviced while the flash isn't in array
+ * mode. This is ensured by the xip_disable() and xip_enable() functions
+ * enclosing any code path where the flash is known not to be in array mode.
+ * And within a XIP disabled code path, only functions marked with __xipram
+ * may be called and nothing else (it's a good thing to inspect generated
+ * assembly to make sure inline functions were actually inlined and that gcc
+ * didn't emit calls to its own support functions). Also configuring MTD CFI
+ * support to a single buswidth and a single interleave is also recommended.
+ */
+
+static void xip_disable(struct map_info *map, struct flchip *chip,
+ unsigned long adr)
+{
+ /* TODO: chips with no XIP use should ignore and return */
+ (void) map_read(map, adr); /* ensure mmu mapping is up to date */
+ local_irq_disable();
+}
+
+static void __xipram xip_enable(struct map_info *map, struct flchip *chip,
+ unsigned long adr)
+{
+ struct cfi_private *cfi = map->fldrv_priv;
+
+ if (chip->state != FL_POINT && chip->state != FL_READY) {
+ map_write(map, CMD(0xf0), adr);
+ chip->state = FL_READY;
+ }
+ (void) map_read(map, adr);
+ xip_iprefetch();
+ local_irq_enable();
+}
+
+/*
+ * When a delay is required for the flash operation to complete, the
+ * xip_udelay() function is polling for both the given timeout and pending
+ * (but still masked) hardware interrupts. Whenever there is an interrupt
+ * pending then the flash erase operation is suspended, array mode restored
+ * and interrupts unmasked. Task scheduling might also happen at that
+ * point. The CPU eventually returns from the interrupt or the call to
+ * schedule() and the suspended flash operation is resumed for the remaining
+ * of the delay period.
+ *
+ * Warning: this function _will_ fool interrupt latency tracing tools.
+ */
+
+static void __xipram xip_udelay(struct map_info *map, struct flchip *chip,
+ unsigned long adr, int usec)
+{
+ struct cfi_private *cfi = map->fldrv_priv;
+ struct cfi_pri_amdstd *extp = cfi->cmdset_priv;
+ map_word status, OK = CMD(0x80);
+ unsigned long suspended, start = xip_currtime();
+ flstate_t oldstate;
+
+ do {
+ cpu_relax();
+ if (xip_irqpending() && extp &&
+ ((chip->state == FL_ERASING && (extp->EraseSuspend & 2))) &&
+ (cfi_interleave_is_1(cfi) || chip->oldstate == FL_READY)) {
+ /*
+ * Let's suspend the erase operation when supported.
+ * Note that we currently don't try to suspend
+ * interleaved chips if there is already another
+ * operation suspended (imagine what happens
+ * when one chip was already done with the current
+ * operation while another chip suspended it, then
+ * we resume the whole thing at once). Yes, it
+ * can happen!
+ */
+ map_write(map, CMD(0xb0), adr);
+ usec -= xip_elapsed_since(start);
+ suspended = xip_currtime();
+ do {
+ if (xip_elapsed_since(suspended) > 100000) {
+ /*
+ * The chip doesn't want to suspend
+ * after waiting for 100 msecs.
+ * This is a critical error but there
+ * is not much we can do here.
+ */
+ return;
+ }
+ status = map_read(map, adr);
+ } while (!map_word_andequal(map, status, OK, OK));
+
+ /* Suspend succeeded */
+ oldstate = chip->state;
+ if (!map_word_bitsset(map, status, CMD(0x40)))
+ break;
+ chip->state = FL_XIP_WHILE_ERASING;
+ chip->erase_suspended = 1;
+ map_write(map, CMD(0xf0), adr);
+ (void) map_read(map, adr);
+ asm volatile (".rep 8; nop; .endr");
+ local_irq_enable();
+ spin_unlock(chip->mutex);
+ asm volatile (".rep 8; nop; .endr");
+ cond_resched();
+
+ /*
+ * We're back. However someone else might have
+ * decided to go write to the chip if we are in
+ * a suspended erase state. If so let's wait
+ * until it's done.
+ */
+ spin_lock(chip->mutex);
+ while (chip->state != FL_XIP_WHILE_ERASING) {
+ DECLARE_WAITQUEUE(wait, current);
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ add_wait_queue(&chip->wq, &wait);
+ spin_unlock(chip->mutex);
+ schedule();
+ remove_wait_queue(&chip->wq, &wait);
+ spin_lock(chip->mutex);
+ }
+ /* Disallow XIP again */
+ local_irq_disable();
+
+ /* Resume the write or erase operation */
+ map_write(map, CMD(0x30), adr);
+ chip->state = oldstate;
+ start = xip_currtime();
+ } else if (usec >= 1000000/HZ) {
+ /*
+ * Try to save on CPU power when waiting delay
+ * is at least a system timer tick period.
+ * No need to be extremely accurate here.
+ */
+ xip_cpu_idle();
+ }
+ status = map_read(map, adr);
+ } while (!map_word_andequal(map, status, OK, OK)
+ && xip_elapsed_since(start) < usec);
+}
+
+#define UDELAY(map, chip, adr, usec) xip_udelay(map, chip, adr, usec)
+
+/*
+ * The INVALIDATE_CACHED_RANGE() macro is normally used in parallel while
+ * the flash is actively programming or erasing since we have to poll for
+ * the operation to complete anyway. We can't do that in a generic way with
+ * a XIP setup so do it before the actual flash operation in this case
+ * and stub it out from INVALIDATE_CACHE_UDELAY.
+ */
+#define XIP_INVAL_CACHED_RANGE(map, from, size) \
+ INVALIDATE_CACHED_RANGE(map, from, size)
+
+#define INVALIDATE_CACHE_UDELAY(map, chip, adr, len, usec) \
+ UDELAY(map, chip, adr, usec)
+
+/*
+ * Extra notes:
+ *
+ * Activating this XIP support changes the way the code works a bit. For
+ * example the code to suspend the current process when concurrent access
+ * happens is never executed because xip_udelay() will always return with the
+ * same chip state as it was entered with. This is why there is no care for
+ * the presence of add_wait_queue() or schedule() calls from within a couple
+ * xip_disable()'d areas of code, like in do_erase_oneblock for example.
+ * The queueing and scheduling are always happening within xip_udelay().
+ *
+ * Similarly, get_chip() and put_chip() just happen to always be executed
+ * with chip->state set to FL_READY (or FL_XIP_WHILE_*) where flash state
+ * is in array mode, therefore never executing many cases therein and not
+ * causing any problem with XIP.
+ */
+
+#else
+
+#define xip_disable(map, chip, adr)
+#define xip_enable(map, chip, adr)
+#define XIP_INVAL_CACHED_RANGE(x...)
+
+#define UDELAY(map, chip, adr, usec) \
+do { \
+ spin_unlock(chip->mutex); \
+ cfi_udelay(usec); \
+ spin_lock(chip->mutex); \
+} while (0)
+
+#define INVALIDATE_CACHE_UDELAY(map, chip, adr, len, usec) \
+do { \
+ spin_unlock(chip->mutex); \
+ INVALIDATE_CACHED_RANGE(map, adr, len); \
+ cfi_udelay(usec); \
+ spin_lock(chip->mutex); \
+} while (0)
+
+#endif