Hi Dmitry
I am curious about how reset gpio works and I think the reset gpio
at low level after elants_i2c_power_on(),
So that the controller won't response anyway, please see below my
question and correct me if I am wrong.
> -----Original Message-----
> From: Dmitry Torokhov [mailto:d...@chromium.org]
> Sent: Thursday, August 06, 2015 2:54 AM
> To: linux-input@vger.kernel.org
> Cc: Rob Herring; Mark Rutland; Benson Leung; Duson Lin; Scott Liu; James
> Chen; devicet...@vger.kernel.org; linux-ker...@vger.kernel.org;
> linux-input@vger.kernel.org
> Subject: [PATCH] Input: elants_i2c - wire up regulator support
>
> Elan touchscreen controllers use two power supplies, vcc33 and vccio, and
> we need to enable them before trying to access the device. On X86 firmware
> usually does this, but on ARM it is usually left to the kernel.
>
> Signed-off-by: Dmitry Torokhov <d...@chromium.org>
> Reviewed-by: Benson Leung <ble...@chromium.org>
> Signed-off-by: Dmitry Torokhov <dmitry.torok...@gmail.com>
> ---
> .../devicetree/bindings/input/elants_i2c.txt | 3 +
> drivers/input/touchscreen/elants_i2c.c | 184
> ++++++++++++++++++---
> 2 files changed, 165 insertions(+), 22 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/input/elants_i2c.txt
> b/Documentation/devicetree/bindings/input/elants_i2c.txt
> index a765232..8a71038 100644
> --- a/Documentation/devicetree/bindings/input/elants_i2c.txt
> +++ b/Documentation/devicetree/bindings/input/elants_i2c.txt
> @@ -13,6 +13,9 @@ Optional properties:
> - pinctrl-names: should be "default" (see pinctrl binding [1]).
> - pinctrl-0: a phandle pointing to the pin settings for the device (see
> pinctrl binding [1]).
> +- reset-gpios: reset gpio the chip is connected to.
> +- vcc33-supply: a phandle for the regulator supplying 3.3V power.
> +- vccio-supply: a phandle for the regulator supplying IO power.
>
> [0]:
Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
> [1]: Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
> diff --git a/drivers/input/touchscreen/elants_i2c.c
> b/drivers/input/touchscreen/elants_i2c.c
> index 42e43f1..1912265 100644
> --- a/drivers/input/touchscreen/elants_i2c.c
> +++ b/drivers/input/touchscreen/elants_i2c.c
> @@ -38,6 +38,8 @@
> #include <linux/input/mt.h>
> #include <linux/acpi.h>
> #include <linux/of.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/regulator/consumer.h>
> #include <asm/unaligned.h>
>
> /* Device, Driver information */
> @@ -102,6 +104,9 @@
> /* calibration timeout definition */
> #define ELAN_CALI_TIMEOUT_MSEC 10000
>
> +#define ELAN_POWERON_DELAY_USEC 500
> +#define ELAN_RESET_DELAY_MSEC 20
> +
> enum elants_state {
> ELAN_STATE_NORMAL,
> ELAN_WAIT_QUEUE_HEADER,
> @@ -118,6 +123,10 @@ struct elants_data {
> struct i2c_client *client;
> struct input_dev *input;
>
> + struct regulator *vcc33;
> + struct regulator *vccio;
> + struct gpio_desc *reset_gpio;
> +
> u16 fw_version;
> u8 test_version;
> u8 solution_version;
> @@ -141,6 +150,7 @@ struct elants_data {
> u8 buf[MAX_PACKET_SIZE];
>
> bool wake_irq_enabled;
> + bool keep_power_in_suspend;
> };
>
> static int elants_i2c_send(struct i2c_client *client, @@ -1058,6 +1068,67
> @@ static void elants_i2c_remove_sysfs_group(void *_data)
> sysfs_remove_group(&ts->client->dev.kobj,
> &elants_attribute_group); }
>
> +static int elants_i2c_power_on(struct elants_data *ts) {
> + int error;
> +
> + /*
> + * If we do not have reset gpio assume platform firmware
> + * controls regulators and does power them on for us.
> + */
> + if (IS_ERR_OR_NULL(ts->reset_gpio))
> + return 0;
> +
> + gpiod_set_value_cansleep(ts->reset_gpio, 1);
> +
> + error = regulator_enable(ts->vcc33);
> + if (error) {
> + dev_err(&ts->client->dev,
> + "failed to enable vcc33 regulator: %d\n",
> + error);
> + goto release_reset_gpio;
> + }
> +
> + error = regulator_enable(ts->vccio);
> + if (error) {
> + dev_err(&ts->client->dev,
> + "failed to enable vccio regulator: %d\n",
> + error);
> + regulator_disable(ts->vcc33);
> + goto release_reset_gpio;
> + }
> +
> + /*
> + * We need to wait a bit after powering on controller before
> + * we are allowed to release reset GPIO.
> + */
> + udelay(ELAN_POWERON_DELAY_USEC);
> +
> +release_reset_gpio:
> + gpiod_set_value_cansleep(ts->reset_gpio, 0);
> + if (error)
> + return error;
> +
> + msleep(ELAN_RESET_DELAY_MSEC);
> +
> + return 0;
> +}
> +
> +static void elants_i2c_power_off(void *_data) {
> + struct elants_data *ts = _data;
> +
> + if (!IS_ERR_OR_NULL(ts->reset_gpio)) {
> + /*
> + * Activate reset gpio to prevent leakage through the
> + * pin once we shut off power to the controller.
> + */
> + gpiod_set_value_cansleep(ts->reset_gpio, 1);
> + regulator_disable(ts->vccio);
> + regulator_disable(ts->vcc33);
> + }
> +}
> +
> static int elants_i2c_probe(struct i2c_client *client,
> const struct i2c_device_id *id)
> {
> @@ -1072,13 +1143,6 @@ static int elants_i2c_probe(struct i2c_client
> *client,
> return -ENXIO;
> }
>
> - /* Make sure there is something at this address */
> - if (i2c_smbus_xfer(client->adapter, client->addr, 0,
> - I2C_SMBUS_READ, 0, I2C_SMBUS_BYTE, &dummy) < 0) {
> - dev_err(&client->dev, "nothing at this address\n");
> - return -ENXIO;
> - }
> -
> ts = devm_kzalloc(&client->dev, sizeof(struct elants_data),
> GFP_KERNEL);
> if (!ts)
> return -ENOMEM;
> @@ -1089,6 +1153,70 @@ static int elants_i2c_probe(struct i2c_client
> *client,
> ts->client = client;
> i2c_set_clientdata(client, ts);
>
> + ts->vcc33 = devm_regulator_get(&client->dev, "vcc33");
> + if (IS_ERR(ts->vcc33)) {
> + error = PTR_ERR(ts->vcc33);
> + if (error != -EPROBE_DEFER)
> + dev_err(&client->dev,
> + "Failed to get 'vcc33' regulator: %d\n",
> + error);
> + return error;
> + }
> +
> + ts->vccio = devm_regulator_get(&client->dev, "vccio");
> + if (IS_ERR(ts->vccio)) {
> + error = PTR_ERR(ts->vccio);
> + if (error != -EPROBE_DEFER)
> + dev_err(&client->dev,
> + "Failed to get 'vccio' regulator: %d\n",
> + error);
> + return error;
> + }
> +
> + ts->reset_gpio = devm_gpiod_get(&client->dev, "reset");
> + if (IS_ERR(ts->reset_gpio)) {
> + error = PTR_ERR(ts->reset_gpio);
> +
> + if (error == -EPROBE_DEFER)
> + return error;
> +
> + if (error != -ENOENT && error != -ENOSYS) {
> + dev_err(&client->dev,
> + "failed to get reset gpio: %d\n",
> + error);
> + return error;
> + }
> +
> + ts->keep_power_in_suspend = true;
> + } else {
> + error = gpiod_direction_output(ts->reset_gpio, 0);
Does it mean to reset our controller? (reset gpio pull low).
> + if (error) {
> + dev_err(&client->dev,
> + "failed to configure reset gpio as output:
%d\n",
> + error);
> + return error;
> + }
> + }
> +
> + error = elants_i2c_power_on(ts);
If reset gpio is at low, controller won't response initialize flow.
I am curious that does reset pin be at low level after
elants_i2c_power_on(ts)?
Thanks,
Scott
> + if (error)
> + return error;
> +
> + error = devm_add_action(&client->dev, elants_i2c_power_off, ts);
> + if (error) {
> + dev_err(&client->dev,
> + "failed to install power off action: %d\n", error);
> + elants_i2c_power_off(ts);
> + return error;
> + }
> +
> + /* Make sure there is something at this address */
> + if (i2c_smbus_xfer(client->adapter, client->addr, 0,
> + I2C_SMBUS_READ, 0, I2C_SMBUS_BYTE, &dummy) < 0) {
> + dev_err(&client->dev, "nothing at this address\n");
> + return -ENXIO;
> + }
> +
> error = elants_i2c_initialize(ts);
> if (error) {
> dev_err(&client->dev, "failed to initialize: %d\n", error);
@@
> -1196,17 +1324,23 @@ static int __maybe_unused elants_i2c_suspend(struct
> device *dev)
>
> disable_irq(client->irq);
>
> - for (retry_cnt = 0; retry_cnt < MAX_RETRIES; retry_cnt++) {
> - error = elants_i2c_send(client, set_sleep_cmd,
> - sizeof(set_sleep_cmd));
> - if (!error)
> - break;
> + if (device_may_wakeup(dev) || ts->keep_power_in_suspend) {
> + for (retry_cnt = 0; retry_cnt < MAX_RETRIES; retry_cnt++) {
> + error = elants_i2c_send(client, set_sleep_cmd,
> + sizeof(set_sleep_cmd));
> + if (!error)
> + break;
>
> - dev_err(&client->dev, "suspend command failed: %d\n",
error);
> - }
> + dev_err(&client->dev,
> + "suspend command failed: %d\n", error);
> + }
>
> - if (device_may_wakeup(dev))
> - ts->wake_irq_enabled = (enable_irq_wake(client->irq) == 0);
> + if (device_may_wakeup(dev))
> + ts->wake_irq_enabled =
> + (enable_irq_wake(client->irq) == 0);
> + } else {
> + elants_i2c_power_off(ts);
> + }
>
> return 0;
> }
> @@ -1222,13 +1356,19 @@ static int __maybe_unused
> elants_i2c_resume(struct device *dev)
> if (device_may_wakeup(dev) && ts->wake_irq_enabled)
> disable_irq_wake(client->irq);
>
> - for (retry_cnt = 0; retry_cnt < MAX_RETRIES; retry_cnt++) {
> - error = elants_i2c_send(client, set_active_cmd,
> - sizeof(set_active_cmd));
> - if (!error)
> - break;
> + if (ts->keep_power_in_suspend) {
> + for (retry_cnt = 0; retry_cnt < MAX_RETRIES; retry_cnt++) {
> + error = elants_i2c_send(client, set_active_cmd,
> + sizeof(set_active_cmd));
> + if (!error)
> + break;
>
> - dev_err(&client->dev, "resume command failed: %d\n", error);
> + dev_err(&client->dev,
> + "resume command failed: %d\n", error);
> + }
> + } else {
> + elants_i2c_power_on(ts);
> + elants_i2c_initialize(ts);
> }
>
> ts->state = ELAN_STATE_NORMAL;
> --
> 2.5.0.rc2.392.g76e840b
>
>
> --
> Dmitry
--
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