Be more compatible with the hwmon framework:
- Hook up to hwmon
* show sensor attrubites only if hwmon is present
* otherwise be just a touchscreen
- Report voltages per hwmon convention
* measure in millivolts
* voltages are named in[0-8]_input (ugh)
* for 7846 chips, properly range-adjust vBATT/in1_input
Battery measurements help during recharge monitoring. On OSK/Mistral,
the measured voltage agreed with a multimeter to several decimal places.
Signed-off-by: David Brownell <[email protected]>
Index: osk/drivers/input/touchscreen/Kconfig
===================================================================
--- osk.orig/drivers/input/touchscreen/Kconfig 2006-12-22 11:08:09.000000000 -0800
+++ osk/drivers/input/touchscreen/Kconfig 2006-12-22 11:08:44.000000000 -0800
@@ -12,12 +12,15 @@ menuconfig INPUT_TOUCHSCREEN
if INPUT_TOUCHSCREEN
config TOUCHSCREEN_ADS7846
- tristate "ADS 7846 based touchscreens"
+ tristate "ADS 7846/7843 based touchscreens"
depends on SPI_MASTER
help
Say Y here if you have a touchscreen interface using the
- ADS7846 controller, and your board-specific initialization
+ ADS7846 or ADS7843 controller, and your board-specific setup
code includes that in its table of SPI devices.
+
+ If HWMON is selected, you will also get hwmon interfaces for
+ the voltage (and for ads7846, temperature) sensors on this chip.
If unsure, say N (but it's safe to say "Y").
Index: osk/drivers/input/touchscreen/ads7846.c
===================================================================
--- osk.orig/drivers/input/touchscreen/ads7846.c 2006-12-22 11:08:43.000000000 -0800
+++ osk/drivers/input/touchscreen/ads7846.c 2006-12-22 11:08:44.000000000 -0800
@@ -17,8 +17,9 @@
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
-#include <linux/device.h>
+#include <linux/hwmon.h>
#include <linux/init.h>
+#include <linux/err.h>
#include <linux/delay.h>
#include <linux/input.h>
#include <linux/interrupt.h>
@@ -77,6 +78,7 @@ struct ads7846 {
struct spi_device *spi;
struct attribute_group *attr_group;
+ struct class_device *hwmon;
u16 model;
u16 vref_delay_usecs;
u16 x_plate_ohms;
@@ -169,7 +171,12 @@ struct ads7846 {
/*
* Non-touchscreen sensors only use single-ended conversions.
+ * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
+ * ads7846 lets that pin be unconnected, to use internal vREF.
+ *
+ * FIXME make external vREF_mV be a module option, and use that as needed...
*/
+static const unsigned vREF_mV = 2500;
struct ser_req {
u8 ref_on;
@@ -197,50 +204,55 @@ static int ads7846_read12_ser(struct dev
struct ser_req *req = kzalloc(sizeof *req, GFP_KERNEL);
int status;
int sample;
- int i;
+ int use_internal;
if (!req)
return -ENOMEM;
spi_message_init(&req->msg);
- /* activate reference, so it has time to settle; */
- req->ref_on = REF_ON;
- req->xfer[0].tx_buf = &req->ref_on;
- req->xfer[0].len = 1;
- req->xfer[1].rx_buf = &req->scratch;
- req->xfer[1].len = 2;
+ /* FIXME boards with ads7846 might use external vref instead ... */
+ use_internal = (ts->model == 7846);
- /*
- * for external VREF, 0 usec (and assume it's always on);
- * for 1uF, use 800 usec;
- * no cap, 100 usec.
- */
- req->xfer[1].delay_usecs = ts->vref_delay_usecs;
+ /* maybe turn on internal vREF, and let it settle */
+ if (use_internal) {
+ req->ref_on = REF_ON;
+ req->xfer[0].tx_buf = &req->ref_on;
+ req->xfer[0].len = 1;
+ spi_message_add_tail(&req->xfer[0], &req->msg);
+
+ req->xfer[1].rx_buf = &req->scratch;
+ req->xfer[1].len = 2;
+
+ /* for 1uF, settle for 800 usec; no cap, 100 usec. */
+ req->xfer[1].delay_usecs = ts->vref_delay_usecs;
+ spi_message_add_tail(&req->xfer[1], &req->msg);
+ }
/* take sample */
req->command = (u8) command;
req->xfer[2].tx_buf = &req->command;
req->xfer[2].len = 1;
+ spi_message_add_tail(&req->xfer[2], &req->msg);
+
req->xfer[3].rx_buf = &req->sample;
req->xfer[3].len = 2;
+ spi_message_add_tail(&req->xfer[3], &req->msg);
/* REVISIT: take a few more samples, and compare ... */
- /* turn off reference */
- req->ref_off = REF_OFF;
- req->xfer[4].tx_buf = &req->ref_off;
- req->xfer[4].len = 1;
- req->xfer[5].rx_buf = &req->scratch;
- req->xfer[5].len = 2;
-
- CS_CHANGE(req->xfer[5]);
+ /* maybe off internal vREF */
+ if (use_internal) {
+ req->ref_off = REF_OFF;
+ req->xfer[4].tx_buf = &req->ref_off;
+ req->xfer[4].len = 1;
+ spi_message_add_tail(&req->xfer[4], &req->msg);
- /* group all the transfers together, so we can't interfere with
- * reading touchscreen state; disable penirq while sampling
- */
- for (i = 0; i < 6; i++)
- spi_message_add_tail(&req->xfer[i], &req->msg);
+ req->xfer[5].rx_buf = &req->scratch;
+ req->xfer[5].len = 2;
+ CS_CHANGE(req->xfer[5]);
+ spi_message_add_tail(&req->xfer[5], &req->msg);
+ }
ts->irq_disabled = 1;
disable_irq(spi->irq);
@@ -260,21 +272,63 @@ static int ads7846_read12_ser(struct dev
return status ? status : sample;
}
-#define SHOW(name) static ssize_t \
+#ifdef CONFIG_HWMON
+
+#define SHOW(name,var,adjust) static ssize_t \
name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
{ \
+ struct ads7846 *ts = dev_get_drvdata(dev); \
ssize_t v = ads7846_read12_ser(dev, \
- READ_12BIT_SER(name) | ADS_PD10_ALL_ON); \
+ READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
if (v < 0) \
return v; \
- return sprintf(buf, "%u\n", (unsigned) v); \
+ return sprintf(buf, "%u\n", adjust(ts, v)); \
} \
static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
-SHOW(temp0)
-SHOW(temp1)
-SHOW(vaux)
-SHOW(vbatt)
+
+/* Sysfs conventions report temperatures in millidegrees Celcius.
+ * We could use the low-accuracy two-sample scheme, but can't do the high
+ * accuracy scheme without calibration data. For now we won't try either;
+ * userspace sees raw sensor values, and must scale appropriately.
+ */
+static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
+{
+ return v;
+}
+
+SHOW(temp0, temp0, null_adjust) // temp1_input
+SHOW(temp1, temp1, null_adjust) // temp2_input
+
+
+/* sysfs conventions report voltages in millivolts. We can convert voltages
+ * if we know vREF. userspace may need to scale vAUX to match the board's
+ * external resistors; we assume that vBATT only uses the internal ones.
+ */
+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 = retval >> 12;
+ return retval;
+}
+
+static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
+{
+ unsigned retval = vaux_adjust(ts, v);
+
+ /* ads7846 has a resistor ladder to scale this signal down */
+ if (ts->model == 7846)
+ retval *= 4;
+ return retval;
+}
+
+SHOW(in0_input, vaux, vaux_adjust)
+SHOW(in1_input, vbatt, vbatt_adjust)
+
+#endif
static int is_pen_down(struct device *dev)
{
@@ -323,10 +377,12 @@ static ssize_t ads7846_disable_store(str
static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
static struct attribute *ads7846_attributes[] = {
+#ifdef CONFIG_HWMON
&dev_attr_temp0.attr,
&dev_attr_temp1.attr,
- &dev_attr_vbatt.attr,
- &dev_attr_vaux.attr,
+ &dev_attr_in0_input.attr,
+ &dev_attr_in1_input.attr,
+#endif
&dev_attr_pen_down.attr,
&dev_attr_disable.attr,
NULL,
@@ -336,14 +392,16 @@ static struct attribute_group ads7846_at
.attrs = ads7846_attributes,
};
+#ifdef CONFIG_HWMON
+
/*
* ads7843/7845 don't have temperature sensors, and
* use the other sensors a bit differently too
*/
static struct attribute *ads7843_attributes[] = {
- &dev_attr_vbatt.attr,
- &dev_attr_vaux.attr,
+ &dev_attr_in0_input.attr,
+ &dev_attr_in1_input.attr,
&dev_attr_pen_down.attr,
&dev_attr_disable.attr,
NULL,
@@ -354,7 +412,7 @@ static struct attribute_group ads7843_at
};
static struct attribute *ads7845_attributes[] = {
- &dev_attr_vaux.attr,
+ &dev_attr_in0_input.attr,
&dev_attr_pen_down.attr,
&dev_attr_disable.attr,
NULL,
@@ -364,6 +422,11 @@ static struct attribute_group ads7845_at
.attrs = ads7845_attributes,
};
+#else
+#define ads7843_attr_group ads7846_attr_group
+#define ads7845_attr_group ads7846_attr_group
+#endif
+
/*--------------------------------------------------------------------------*/
/*
@@ -712,6 +775,14 @@ static int __devinit ads7846_probe(struc
err = -ENOMEM;
goto err_free_mem;
}
+#ifdef CONFIG_HWMON
+ ts->hwmon = hwmon_device_register(&spi->dev);
+ if (IS_ERR(ts->hwmon)) {
+ err = PTR_ERR(ts->hwmon);
+ ts->hwmon = NULL;
+ goto err_free_mem;
+ }
+#endif
dev_set_drvdata(&spi->dev, ts);
spi->dev.power.power_state = PMSG_ON;
@@ -876,9 +947,11 @@ static int __devinit ads7846_probe(struc
goto err_cleanup_filter;
}
- dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
+ dev_info(&spi->dev, "touchscreen%s, irq %d\n",
+ ts->hwmon ? " + hwmon" : "",
+ spi->irq);
- /* take a first sample, leaving nPENIRQ active; avoid
+ /* take a first sample, leaving nPENIRQ active and vREF off; avoid
* the touchscreen, in case it's not connected.
*/
(void) ads7846_read12_ser(&spi->dev,
@@ -913,6 +986,10 @@ static int __devinit ads7846_probe(struc
if (ts->filter_cleanup)
ts->filter_cleanup(ts->filter_data);
err_free_mem:
+#ifdef CONFIG_HWMON
+ if (ts->hwmon)
+ hwmon_device_unregister(ts->hwmon);
+#endif
input_free_device(input_dev);
kfree(ts);
return err;
@@ -922,6 +999,9 @@ static int __devexit ads7846_remove(stru
{
struct ads7846 *ts = dev_get_drvdata(&spi->dev);
+#ifdef CONFIG_HWMON
+ hwmon_device_unregister(ts->hwmon);
+#endif
input_unregister_device(ts->input);
ads7846_suspend(spi, PMSG_SUSPEND);
-
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