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>

diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index 57a1c28..a571aa9 100644 (file)
--- 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 334d314..daf7440 100644 (file)
--- 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