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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>
This commit is contained in:
David Brownell 2008-04-02 00:43:01 -04:00 committed by Dmitry Torokhov
parent e6cdd15629
commit 7c6d0ee14c
2 changed files with 12 additions and 13 deletions
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22
drivers/input/touchscreen/ads7846.c
View File

@ -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;

3
include/linux/spi/ads7846.h
View File

@ -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