[ARM] S3C: ADC: Expose number of remaining conversions to
convert callback

This patch allow us to efficiently modify the number of
remaining conversions from the client side. This us useful
when we do not know in advance how many conversions we will
need or when we need to cancel pending conversions.

This change is simple enough to be compatible with existing
code that can just define the new pointer in the callback
and ignore it.

Sample usage:

http://tinyurl.com/s3c2410-ts-c (function stylus_adc_action).

Signed-off-by: Nelson Castillo <arhuaco@freaks-unidos.net>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
diff --git a/arch/arm/plat-s3c24xx/adc.c b/arch/arm/plat-s3c24xx/adc.c
index 91adfa7..ee1baf1 100644
--- a/arch/arm/plat-s3c24xx/adc.c
+++ b/arch/arm/plat-s3c24xx/adc.c
@@ -45,7 +45,8 @@
 	unsigned char		 channel;
 
 	void	(*select_cb)(unsigned selected);
-	void	(*convert_cb)(unsigned val1, unsigned val2);
+	void	(*convert_cb)(unsigned val1, unsigned val2,
+			      unsigned *samples_left);
 };
 
 struct adc_device {
@@ -158,7 +159,8 @@
 
 struct s3c_adc_client *s3c_adc_register(struct platform_device *pdev,
 					void (*select)(unsigned int selected),
-					void (*conv)(unsigned d0, unsigned d1),
+					void (*conv)(unsigned d0, unsigned d1,
+						     unsigned *samples_left),
 					unsigned int is_ts)
 {
 	struct s3c_adc_client *client;
@@ -227,9 +229,10 @@
 	data1 = readl(adc->regs + S3C2410_ADCDAT1);
 	adc_dbg(adc, "read %d: 0x%04x, 0x%04x\n", client->nr_samples, data0, data1);
 
-	(client->convert_cb)(data0 & 0x3ff, data1 & 0x3ff);
+	client->nr_samples--;
+	(client->convert_cb)(data0 & 0x3ff, data1 & 0x3ff, &client->nr_samples);
 
-	if (--client->nr_samples > 0) {
+	if (client->nr_samples > 0) {
 		/* fire another conversion for this */
 
 		client->select_cb(1);