| Message ID | 20210521044525.7397-9-o.rempel@pengutronix.de (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | add z1 and z2 channels support for resistive-adc-touch driver | expand |
On Fri, 21 May 2021 06:45:25 +0200 Oleksij Rempel <o.rempel@pengutronix.de> wrote: > This patch adds support for the z1 and z2 channels. These are used to > calculate the applied pressure. As there is no common order of the > individual channels of a resistive touch ADC, support for > io-channel-names is added (although the DT bindings stated the > driver already supports these). > > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> One minor comment inline, but otherwise looks good to me. Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Would be nice at some point to make this handle channels that aren't 16 bits, but that can be a job for another day. Jonathan > --- > .../input/touchscreen/resistive-adc-touch.c | 142 ++++++++++++++++-- > 1 file changed, 128 insertions(+), 14 deletions(-) > > diff --git a/drivers/input/touchscreen/resistive-adc-touch.c b/drivers/input/touchscreen/resistive-adc-touch.c > index e50af30183f4..fa90005b7bc9 100644 > --- a/drivers/input/touchscreen/resistive-adc-touch.c > +++ b/drivers/input/touchscreen/resistive-adc-touch.c > @@ -20,7 +20,18 @@ > > #define DRIVER_NAME "resistive-adc-touch" > #define GRTS_DEFAULT_PRESSURE_MIN 50000 > +#define GRTS_DEFAULT_PRESSURE_MAX 65535 > #define GRTS_MAX_POS_MASK GENMASK(11, 0) > +#define GRTS_MAX_CHANNELS 4 > + > +enum grts_ch_type { > + GRTS_CH_NONE = 0, > + GRTS_CH_X, > + GRTS_CH_Y, > + GRTS_CH_PRESSURE, > + GRTS_CH_Z1, > + GRTS_CH_Z2, > +}; > > /** > * struct grts_state - generic resistive touch screen information struct > @@ -33,24 +44,61 @@ > */ > struct grts_state { > u32 pressure_min; > + u32 x_plate_ohms; > bool pressure; > struct iio_channel *iio_chans; > struct iio_cb_buffer *iio_cb; > struct input_dev *input; > struct touchscreen_properties prop; > + u8 ch[GRTS_MAX_CHANNELS]; > }; > > static int grts_cb(const void *data, void *private) > { > const u16 *touch_info = data; > struct grts_state *st = private; > - unsigned int x, y, press = 0x0; > + unsigned int x, y, press = 0, z1 = 0, z2; > + unsigned int Rt, i; > + > + for (i = 0; i < ARRAY_SIZE(st->ch) && st->ch[i] != GRTS_CH_NONE; i++) { > + switch (st->ch[i]) { > + case GRTS_CH_X: > + x = touch_info[i]; > + break; > + case GRTS_CH_Y: > + y = touch_info[i]; > + break; > + case GRTS_CH_PRESSURE: > + press = touch_info[i]; > + break; > + case GRTS_CH_Z1: > + z1 = touch_info[i]; > + break; > + case GRTS_CH_Z2: > + z2 = touch_info[i]; > + break; > + case GRTS_CH_NONE: Loop condition above prevents this. I guess you might get a warning though so if this is just warning suppression then add a comment to say so to make sure it isn't removed. > + break; > + } > + } > > - /* channel data coming in buffer in the order below */ > - x = touch_info[0]; > - y = touch_info[1]; > - if (st->pressure) > - press = touch_info[2]; > + if (z1) { > + Rt = z2; > + Rt -= z1; > + Rt *= st->x_plate_ohms; > + Rt = DIV_ROUND_CLOSEST(Rt, 16); > + Rt *= x; > + Rt /= z1; > + Rt = DIV_ROUND_CLOSEST(Rt, 256); > + /* > + * On increased pressure the resistance (Rt) is decreasing > + * so, convert values to make it looks as real pressure. > + */ > + if (Rt < GRTS_DEFAULT_PRESSURE_MAX) > + press = GRTS_DEFAULT_PRESSURE_MAX - Rt; > + else > + press = 0; > + } > > if ((!x && !y) || (st->pressure && (press < st->pressure_min))) { > /* report end of touch */ > @@ -94,12 +142,77 @@ static void grts_disable(void *data) > iio_channel_release_all_cb(data); > } > > +static int grts_get_properties(struct grts_state *st, struct device *dev) > +{ > + int idx, error; > + > + idx = device_property_match_string(dev, "io-channel-names", "x"); > + if (idx < 0) > + return idx; > + > + if (idx >= ARRAY_SIZE(st->ch)) > + return -EOVERFLOW; > + > + st->ch[idx] = GRTS_CH_X; > + > + idx = device_property_match_string(dev, "io-channel-names", "y"); > + if (idx < 0) > + return idx; > + > + if (idx >= ARRAY_SIZE(st->ch)) > + return -EOVERFLOW; > + > + st->ch[idx] = GRTS_CH_Y; > + > + /* pressure is optional */ > + idx = device_property_match_string(dev, "io-channel-names", "pressure"); > + if (idx >= 0) { > + if (idx >= ARRAY_SIZE(st->ch)) > + return -EOVERFLOW; > + > + st->ch[idx] = GRTS_CH_PRESSURE; > + st->pressure = true; > + > + return 0; > + } > + > + /* if no pressure is defined, try optional z1 + z2 */ > + idx = device_property_match_string(dev, "io-channel-names", "z1"); > + if (idx < 0) > + return 0; > + > + if (idx >= ARRAY_SIZE(st->ch)) > + return -EOVERFLOW; > + > + st->ch[idx] = GRTS_CH_Z1; > + > + /* if z1 is provided z2 is not optional */ > + idx = device_property_match_string(dev, "io-channel-names", "z2"); > + if (idx < 0) > + return idx; > + > + if (idx >= ARRAY_SIZE(st->ch)) > + return -EOVERFLOW; > + > + st->ch[idx] = GRTS_CH_Z2; > + st->pressure = true; > + > + error = device_property_read_u32(dev, > + "touchscreen-x-plate-ohms", > + &st->x_plate_ohms); > + if (error) { > + dev_err(dev, "can't get touchscreen-x-plate-ohms property\n"); > + return error; > + } > + > + return 0; > +} > + > static int grts_probe(struct platform_device *pdev) > { > struct grts_state *st; > struct input_dev *input; > struct device *dev = &pdev->dev; > - struct iio_channel *chan; > int error; > > st = devm_kzalloc(dev, sizeof(struct grts_state), GFP_KERNEL); > @@ -115,12 +228,13 @@ static int grts_probe(struct platform_device *pdev) > return error; > } > > - chan = &st->iio_chans[0]; > - st->pressure = false; > - while (chan && chan->indio_dev) { > - if (!strcmp(chan->channel->datasheet_name, "pressure")) > - st->pressure = true; > - chan++; > + if (!device_property_present(dev, "io-channel-names")) > + return -ENODEV; > + > + error = grts_get_properties(st, dev); > + if (error) { > + dev_err(dev, "Failed to parse properties\n"); > + return error; > } > > if (st->pressure) { > @@ -148,7 +262,7 @@ static int grts_probe(struct platform_device *pdev) > input_set_abs_params(input, ABS_Y, 0, GRTS_MAX_POS_MASK - 1, 0, 0); > if (st->pressure) > input_set_abs_params(input, ABS_PRESSURE, st->pressure_min, > - 0xffff, 0, 0); > + GRTS_DEFAULT_PRESSURE_MAX, 0, 0); > > input_set_capability(input, EV_KEY, BTN_TOUCH); >
diff --git a/drivers/input/touchscreen/resistive-adc-touch.c b/drivers/input/touchscreen/resistive-adc-touch.c index e50af30183f4..fa90005b7bc9 100644 --- a/drivers/input/touchscreen/resistive-adc-touch.c +++ b/drivers/input/touchscreen/resistive-adc-touch.c @@ -20,7 +20,18 @@ #define DRIVER_NAME "resistive-adc-touch" #define GRTS_DEFAULT_PRESSURE_MIN 50000 +#define GRTS_DEFAULT_PRESSURE_MAX 65535 #define GRTS_MAX_POS_MASK GENMASK(11, 0) +#define GRTS_MAX_CHANNELS 4 + +enum grts_ch_type { + GRTS_CH_NONE = 0, + GRTS_CH_X, + GRTS_CH_Y, + GRTS_CH_PRESSURE, + GRTS_CH_Z1, + GRTS_CH_Z2, +}; /** * struct grts_state - generic resistive touch screen information struct @@ -33,24 +44,61 @@ */ struct grts_state { u32 pressure_min; + u32 x_plate_ohms; bool pressure; struct iio_channel *iio_chans; struct iio_cb_buffer *iio_cb; struct input_dev *input; struct touchscreen_properties prop; + u8 ch[GRTS_MAX_CHANNELS]; }; static int grts_cb(const void *data, void *private) { const u16 *touch_info = data; struct grts_state *st = private; - unsigned int x, y, press = 0x0; + unsigned int x, y, press = 0, z1 = 0, z2; + unsigned int Rt, i; + + for (i = 0; i < ARRAY_SIZE(st->ch) && st->ch[i] != GRTS_CH_NONE; i++) { + switch (st->ch[i]) { + case GRTS_CH_X: + x = touch_info[i]; + break; + case GRTS_CH_Y: + y = touch_info[i]; + break; + case GRTS_CH_PRESSURE: + press = touch_info[i]; + break; + case GRTS_CH_Z1: + z1 = touch_info[i]; + break; + case GRTS_CH_Z2: + z2 = touch_info[i]; + break; + case GRTS_CH_NONE: + break; + } + } - /* channel data coming in buffer in the order below */ - x = touch_info[0]; - y = touch_info[1]; - if (st->pressure) - press = touch_info[2]; + if (z1) { + Rt = z2; + Rt -= z1; + Rt *= st->x_plate_ohms; + Rt = DIV_ROUND_CLOSEST(Rt, 16); + Rt *= x; + Rt /= z1; + Rt = DIV_ROUND_CLOSEST(Rt, 256); + /* + * On increased pressure the resistance (Rt) is decreasing + * so, convert values to make it looks as real pressure. + */ + if (Rt < GRTS_DEFAULT_PRESSURE_MAX) + press = GRTS_DEFAULT_PRESSURE_MAX - Rt; + else + press = 0; + } if ((!x && !y) || (st->pressure && (press < st->pressure_min))) { /* report end of touch */ @@ -94,12 +142,77 @@ static void grts_disable(void *data) iio_channel_release_all_cb(data); } +static int grts_get_properties(struct grts_state *st, struct device *dev) +{ + int idx, error; + + idx = device_property_match_string(dev, "io-channel-names", "x"); + if (idx < 0) + return idx; + + if (idx >= ARRAY_SIZE(st->ch)) + return -EOVERFLOW; + + st->ch[idx] = GRTS_CH_X; + + idx = device_property_match_string(dev, "io-channel-names", "y"); + if (idx < 0) + return idx; + + if (idx >= ARRAY_SIZE(st->ch)) + return -EOVERFLOW; + + st->ch[idx] = GRTS_CH_Y; + + /* pressure is optional */ + idx = device_property_match_string(dev, "io-channel-names", "pressure"); + if (idx >= 0) { + if (idx >= ARRAY_SIZE(st->ch)) + return -EOVERFLOW; + + st->ch[idx] = GRTS_CH_PRESSURE; + st->pressure = true; + + return 0; + } + + /* if no pressure is defined, try optional z1 + z2 */ + idx = device_property_match_string(dev, "io-channel-names", "z1"); + if (idx < 0) + return 0; + + if (idx >= ARRAY_SIZE(st->ch)) + return -EOVERFLOW; + + st->ch[idx] = GRTS_CH_Z1; + + /* if z1 is provided z2 is not optional */ + idx = device_property_match_string(dev, "io-channel-names", "z2"); + if (idx < 0) + return idx; + + if (idx >= ARRAY_SIZE(st->ch)) + return -EOVERFLOW; + + st->ch[idx] = GRTS_CH_Z2; + st->pressure = true; + + error = device_property_read_u32(dev, + "touchscreen-x-plate-ohms", + &st->x_plate_ohms); + if (error) { + dev_err(dev, "can't get touchscreen-x-plate-ohms property\n"); + return error; + } + + return 0; +} + static int grts_probe(struct platform_device *pdev) { struct grts_state *st; struct input_dev *input; struct device *dev = &pdev->dev; - struct iio_channel *chan; int error; st = devm_kzalloc(dev, sizeof(struct grts_state), GFP_KERNEL); @@ -115,12 +228,13 @@ static int grts_probe(struct platform_device *pdev) return error; } - chan = &st->iio_chans[0]; - st->pressure = false; - while (chan && chan->indio_dev) { - if (!strcmp(chan->channel->datasheet_name, "pressure")) - st->pressure = true; - chan++; + if (!device_property_present(dev, "io-channel-names")) + return -ENODEV; + + error = grts_get_properties(st, dev); + if (error) { + dev_err(dev, "Failed to parse properties\n"); + return error; } if (st->pressure) { @@ -148,7 +262,7 @@ static int grts_probe(struct platform_device *pdev) input_set_abs_params(input, ABS_Y, 0, GRTS_MAX_POS_MASK - 1, 0, 0); if (st->pressure) input_set_abs_params(input, ABS_PRESSURE, st->pressure_min, - 0xffff, 0, 0); + GRTS_DEFAULT_PRESSURE_MAX, 0, 0); input_set_capability(input, EV_KEY, BTN_TOUCH);
This patch adds support for the z1 and z2 channels. These are used to calculate the applied pressure. As there is no common order of the individual channels of a resistive touch ADC, support for io-channel-names is added (although the DT bindings stated the driver already supports these). Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> --- .../input/touchscreen/resistive-adc-touch.c | 142 ++++++++++++++++-- 1 file changed, 128 insertions(+), 14 deletions(-)