[PATCH 13/22] mfd/ti_tscadc: deal with partial activation

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

From: Pantelis Antoniou <panto@antoniou-consulting.com>

Fix the mfd device in the case where a subdevice might not be activated.

Signed-off-by: Pantelis Antoniou <panto@antoniou-consulting.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
[bigeasy: split out this chunk from the orignal patch, check for neither
          ADC nor TSC channels]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/mfd/ti_am335x_tscadc.c       |   34 +++++++++++++++++++++++-----------
 include/linux/mfd/ti_am335x_tscadc.h |    8 +++-----
 2 files changed, 26 insertions(+), 16 deletions(-)

diff --git a/drivers/mfd/ti_am335x_tscadc.c b/drivers/mfd/ti_am335x_tscadc.c
index 6b85459..857b6e8 100644
--- a/drivers/mfd/ti_am335x_tscadc.c
+++ b/drivers/mfd/ti_am335x_tscadc.c
@@ -96,11 +96,14 @@ static	int ti_tscadc_probe(struct platform_device *pdev)
 	of_property_read_u32(node, "ti,adc-channels", &adc_channels);
 
 	total_channels = tsc_wires + adc_channels;
-
 	if (total_channels > 8) {
 		dev_err(&pdev->dev, "Number of i/p channels more than 8\n");
 		return -EINVAL;
 	}
+	if (total_channels == 0) {
+		dev_err(&pdev->dev, "Need atleast one channel.\n");
+		return -EINVAL;
+	}
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res) {
@@ -183,26 +186,35 @@ static	int ti_tscadc_probe(struct platform_device *pdev)
 	ctrl |= CNTRLREG_TSCSSENB;
 	tscadc_writel(tscadc, REG_CTRL, ctrl);
 
+	tscadc->used_cells = 0;
+	tscadc->tsc_cell = -1;
+	tscadc->adc_cell = -1;
+
 	/* TSC Cell */
-	cell = &tscadc->cells[TSC_CELL];
-	cell->name = "tsc";
-	cell->platform_data = &tscadc;
-	cell->pdata_size = sizeof(tscadc);
+	if (tsc_wires > 0) {
+		tscadc->tsc_cell = tscadc->used_cells;
+		cell = &tscadc->cells[tscadc->used_cells++];
+		cell->name = "tsc";
+		cell->platform_data = &tscadc;
+		cell->pdata_size = sizeof(tscadc);
+	}
 
 	/* ADC Cell */
-	cell = &tscadc->cells[ADC_CELL];
-	cell->name = "tiadc";
-	cell->platform_data = &tscadc;
-	cell->pdata_size = sizeof(tscadc);
+	if (adc_channels > 0) {
+		tscadc->adc_cell = tscadc->used_cells;
+		cell = &tscadc->cells[tscadc->used_cells++];
+		cell->name = "tiadc";
+		cell->platform_data = &tscadc;
+		cell->pdata_size = sizeof(tscadc);
+	}
 
 	err = mfd_add_devices(&pdev->dev, pdev->id, tscadc->cells,
-			TSCADC_CELLS, NULL, 0, NULL);
+			tscadc->used_cells, NULL, 0, NULL);
 	if (err < 0)
 		goto err_disable_clk;
 
 	device_init_wakeup(&pdev->dev, true);
 	platform_set_drvdata(pdev, tscadc);
-
 	return 0;
 
 err_disable_clk:
diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h
index 2d78af8..b6e7ac6 100644
--- a/include/linux/mfd/ti_am335x_tscadc.h
+++ b/include/linux/mfd/ti_am335x_tscadc.h
@@ -127,11 +127,6 @@
 
 #define TSCADC_CELLS		2
 
-enum tscadc_cells {
-	TSC_CELL,
-	ADC_CELL,
-};
-
 struct mfd_tscadc_board {
 	struct tsc_data *tsc_init;
 	struct adc_data *adc_init;
@@ -141,6 +136,9 @@ struct ti_tscadc_dev {
 	struct device *dev;
 	void __iomem *tscadc_base;
 	int irq;
+	int used_cells;	/* 1-2 */
+	int tsc_cell;	/* -1 if not used */
+	int adc_cell;	/* -1 if not used */
 	struct mfd_cell cells[TSCADC_CELLS];
 	u32 reg_se_cache;
 	spinlock_t reg_lock;
-- 
1.7.10.4