MFD: ti_tscadc: Disable TSC config registers in adc mode

AFE Pen Ctrl and TouchScreen transistors enabling is not
required when only ADC mode is being used, so check for availability of
TSC driver before accessing control register.
Signed-off-by: NPatil, Rachna <rachna@ti.com>
Acked-by: NVaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: NZubair Lutfullah <zubair.lutfullah@gmail.com>
Signed-off-by: NLee Jones <lee.jones@linaro.org>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>

drivers/mfd/ti_am335x_tscadc.c

@@ -204,13 +204,14 @@ static	int ti_tscadc_probe(struct platform_device *pdev)
 
 	/* Set the control register bits */
 	ctrl = CNTRLREG_STEPCONFIGWRT |
-			CNTRLREG_TSCENB |
-			CNTRLREG_STEPID |
-			CNTRLREG_4WIRE;
+			CNTRLREG_STEPID;
+	if (tsc_wires > 0)
+		ctrl |= CNTRLREG_4WIRE | CNTRLREG_TSCENB;
 	tscadc_writel(tscadc, REG_CTRL, ctrl);
 
 	/* Set register bits for Idle Config Mode */
-	tscadc_idle_config(tscadc);
+	if (tsc_wires > 0)
+		tscadc_idle_config(tscadc);
 
 	/* Enable the TSC module enable bit */
 	ctrl = tscadc_readl(tscadc, REG_CTRL);
@@ -290,10 +291,13 @@ static int tscadc_resume(struct device *dev)
 	pm_runtime_get_sync(dev);
 
 	/* context restore */
-	ctrl = CNTRLREG_STEPCONFIGWRT | CNTRLREG_TSCENB |
-			CNTRLREG_STEPID | CNTRLREG_4WIRE;
+	ctrl = CNTRLREG_STEPCONFIGWRT |	CNTRLREG_STEPID;
+	if (tscadc_dev->tsc_cell != -1)
+		ctrl |= CNTRLREG_TSCENB | CNTRLREG_4WIRE;
 	tscadc_writel(tscadc_dev, REG_CTRL, ctrl);
-	tscadc_idle_config(tscadc_dev);
+
+	if (tscadc_dev->tsc_cell != -1)
+		tscadc_idle_config(tscadc_dev);
 	am335x_tsc_se_update(tscadc_dev);
 	restore = tscadc_readl(tscadc_dev, REG_CTRL);
 	tscadc_writel(tscadc_dev, REG_CTRL,