staging: olpc_dcon: ->read_status() API change

Change ->read_status() by separating the error handling and the
status bits.  This also fixes a signedness bug in dcon_interrupt()
that would break the error handling.
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Acked-by: Andres Salomon <dilinger@queued.net>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/olpc_dcon/olpc_dcon.c

@@ -755,9 +755,9 @@ static int dcon_resume(struct i2c_client *client)
 irqreturn_t dcon_interrupt(int irq, void *id)
 {
 	struct dcon_priv *dcon = id;
-	int status = pdata->read_status();
+	u8 status;
 
-	if (status == -1)
+	if (pdata->read_status(&status))
 		return IRQ_NONE;
 
 	switch (status & 3) {

drivers/staging/olpc_dcon/olpc_dcon.h

@@ -84,7 +84,7 @@ struct dcon_platform_data {
 	int (*init)(struct dcon_priv *);
 	void (*bus_stabilize_wiggle)(void);
 	void (*set_dconload)(int);
-	u8 (*read_status)(void);
+	int (*read_status)(u8 *);
 };
 
 #include <linux/interrupt.h>

drivers/staging/olpc_dcon/olpc_dcon_xo_1.c

@@ -183,17 +183,15 @@ static void dcon_set_dconload_1(int val)
 	gpio_set_value(OLPC_GPIO_DCON_LOAD, val);
 }
 
-static u8 dcon_read_status_xo_1(void)
+static int dcon_read_status_xo_1(u8 *status)
 {
-	u8 status;
-
-	status = gpio_get_value(OLPC_GPIO_DCON_STAT0);
-	status |= gpio_get_value(OLPC_GPIO_DCON_STAT1) << 1;
+	*status = gpio_get_value(OLPC_GPIO_DCON_STAT0);
+	*status |= gpio_get_value(OLPC_GPIO_DCON_STAT1) << 1;
 
 	/* Clear the negative edge status for GPIO7 */
 	cs5535_gpio_set(OLPC_GPIO_DCON_IRQ, GPIO_NEGATIVE_EDGE_STS);
 
-	return status;
+	return 0;
 }
 
 struct dcon_platform_data dcon_pdata_xo_1 = {

drivers/staging/olpc_dcon/olpc_dcon_xo_1_5.c

@@ -167,20 +167,18 @@ static void dcon_set_dconload_xo_1_5(int val)
 	gpio_set_value(VX855_GPIO(1), val);
 }
 
-static u8 dcon_read_status_xo_1_5(void)
+static int dcon_read_status_xo_1_5(u8 *status)
 {
-	u8 status;
-
 	if (!dcon_was_irq())
 		return -1;
 
 	/* i believe this is the same as "inb(0x44b) & 3" */
-	status = gpio_get_value(VX855_GPI(10));
-	status |= gpio_get_value(VX855_GPI(11)) << 1;
+	*status = gpio_get_value(VX855_GPI(10));
+	*status |= gpio_get_value(VX855_GPI(11)) << 1;
 
 	dcon_clear_irq();
 
-	return status;
+	return 0;
 }
 
 struct dcon_platform_data dcon_pdata_xo_1_5 = {