Input: ads7846 - simplify support of external vREF (and ads7843)

This updates the ads7846 driver to handle external vREF (required
on boards using ads7843 chips) without module parameters, and also
removes a needless variable with its associated bogus gcc warning.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

2 files changed, 12 insertions, 13 deletions

diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index 57a1c28bf122..a571aa965da0 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -87,6 +87,7 @@ struct ads7846 {
 #endif
 
         u16                     model;
+        u16                     vref_mv;
         u16                     vref_delay_usecs;
         u16                     x_plate_ohms;
         u16                     pressure_max;
@@ -184,9 +185,6 @@ struct ads7846 {
  * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
  * ads7846 lets that pin be unconnected, to use internal vREF.
  */
-static unsigned vREF_mV;
-module_param(vREF_mV, uint, 0);
-MODULE_PARM_DESC(vREF_mV, "external vREF voltage, in milliVolts");
 
 struct ser_req {
         u8                      ref_on;
@@ -213,7 +211,6 @@ static int ads7846_read12_ser(struct device *dev, unsigned command)
         struct ads7846          *ts = dev_get_drvdata(dev);
         struct ser_req          *req = kzalloc(sizeof *req, GFP_KERNEL);
         int                     status;
-        int                     uninitialized_var(sample);
         int                     use_internal;
 
         if (!req)
@@ -270,13 +267,13 @@ static int ads7846_read12_ser(struct device *dev, unsigned command)
 
         if (status == 0) {
                 /* on-wire is a must-ignore bit, a BE12 value, then padding */
-                sample = be16_to_cpu(req->sample);
-                sample = sample >> 3;
-                sample &= 0x0fff;
+                status = be16_to_cpu(req->sample);
+                status = status >> 3;
+                status &= 0x0fff;
         }
 
         kfree(req);
-        return status ? status : sample;
+        return status;
 }
 
 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
@@ -317,7 +314,7 @@ static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
         unsigned retval = v;
 
         /* external resistors may scale vAUX into 0..vREF */
-        retval *= vREF_mV;
+        retval *= ts->vref_mv;
         retval = retval >> 12;
         return retval;
 }
@@ -375,14 +372,14 @@ static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
         /* hwmon sensors need a reference voltage */
         switch (ts->model) {
         case 7846:
-                if (!vREF_mV) {
+                if (!ts->vref_mv) {
                         dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
-                        vREF_mV = 2500;
+                        ts->vref_mv = 2500;
                 }
                 break;
         case 7845:
         case 7843:
-                if (!vREF_mV) {
+                if (!ts->vref_mv) {
                         dev_warn(&spi->dev,
                                 "external vREF for ADS%d not specified\n",
                                 ts->model);
@@ -875,6 +872,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
 
         ts->spi = spi;
         ts->input = input_dev;
+        ts->vref_mv = pdata->vref_mv;
 
         hrtimer_init(&ts->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
         ts->timer.function = ads7846_timer;
diff --git a/include/linux/spi/ads7846.h b/include/linux/spi/ads7846.h
index 334d31411629..daf744017a31 100644
--- a/include/linux/spi/ads7846.h
+++ b/include/linux/spi/ads7846.h
@@ -14,7 +14,8 @@ enum ads7846_filter {
 struct ads7846_platform_data {
         u16     model;                  /* 7843, 7845, 7846. */
         u16     vref_delay_usecs;       /* 0 for external vref; etc */
-        int     keep_vref_on:1;         /* set to keep vref on for differential
+        u16     vref_mv;                /* external vref value, milliVolts */
+        bool    keep_vref_on;           /* set to keep vref on for differential
                                          * measurements as well */
 
         /* Settling time of the analog signals; a function of Vcc and the