PSoC4 Low Power Technics state that any interrupt will wake from deep-sleep. No isr-component needed, just an enabled interrupt.
Can make it difficult to find a wakeup cause, looks as if you'll have to read some ICU-registers to get the cause.
Keep in mind that debugging and deep-sleep may not go together!
This ap note should help -
http://www.cypress.com/?rID=95069 AN90799 - PSoC® 4 Interrupts
http://www.cypress.com/?rID=78797 AN86233 - PSoC® 4 Low-Power Modes and Power Reduction Techniques
and GPIO issues in sleep -
http://www.cypress.com/?rID=93401 AN86439 - PSoC® 4 - Using GPIO Pins