mfd: fix pcap irq bottom handler

Mask interrupts before servicing them and loop while pcap asserts the interrupt
line.
Signed-off-by: Daniel Ribeiro <drwyrm@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/mfd/ezx-pcap.c

@@ -17,6 +17,7 @@
 #include <linux/irq.h>
 #include <linux/mfd/ezx-pcap.h>
 #include <linux/spi/spi.h>
+#include <linux/gpio.h>
 
 #define PCAP_ADC_MAXQ		8
 struct pcap_adc_request {
@@ -155,6 +156,7 @@ static void pcap_isr_work(struct work_struct *work)
 	u32 msr, isr, int_sel, service;
 	int irq;
 
+	do {
 		ezx_pcap_read(pcap, PCAP_REG_MSR, &msr);
 		ezx_pcap_read(pcap, PCAP_REG_ISR, &isr);
 
@@ -163,11 +165,12 @@ static void pcap_isr_work(struct work_struct *work)
 			ezx_pcap_read(pcap, PCAP_REG_INT_SEL, &int_sel);
 			isr &= ~int_sel;
 		}
+
+		ezx_pcap_write(pcap, PCAP_REG_MSR, isr | msr);
 		ezx_pcap_write(pcap, PCAP_REG_ISR, isr);
 
 		local_irq_disable();
 		service = isr & ~msr;
-
 		for (irq = pcap->irq_base; service; service >>= 1, irq++) {
 			if (service & 1) {
 				struct irq_desc *desc = irq_to_desc(irq);
@@ -183,6 +186,8 @@ static void pcap_isr_work(struct work_struct *work)
 			}
 		}
 		local_irq_enable();
+		ezx_pcap_write(pcap, PCAP_REG_MSR, pcap->msr);
+	} while (gpio_get_value(irq_to_gpio(pcap->spi->irq)));
 }
 
 static void pcap_irq_handler(unsigned int irq, struct irq_desc *desc)