Re: [PATCH v5 2/3] Input: Add Novatek NT36xxx touchscreen driver

From: Andy Shevchenko
Date: Sun Oct 18 2020 - 15:50:13 EST

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In reply to: kholk11: "[PATCH v5 2/3] Input: Add Novatek NT36xxx touchscreen driver"
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On Sun, Oct 18, 2020 at 12:40 AM <kholk11@xxxxxxxxx> wrote:
>
> From: AngeloGioacchino Del Regno <kholk11@xxxxxxxxx>
>
> This is a driver for the Novatek in-cell touch controller and
> supports various chips from the NT36xxx family, currently
> including NT36525, NT36672A, NT36676F, NT36772 and NT36870.
>
> Functionality like wake gestures and firmware flashing is not
> included: I am not aware of any of these DrIC+Touch combo
> chips not including a non-volatile memory and it should be
> highly unlikely to find one, since the touch firmware is
> embedded into the DriverIC one, which is obviously necessary
> to drive the display unit.
>
> However, the necessary address for the firmware update
> procedure was included into the address table in this driver
> so, in the event that someone finds the need to implement it
> for a reason or another, it will be pretty straightforward to.
>
> This driver is lightly based on the downstream implementation [1].
> [1] https://github.com/Rasenkai/caf-tsoft-Novatek-nt36xxx

...

> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>

> +#include <linux/of_gpio.h>

I haven't found evidence you need this header.
But mod_devicetable.h along with gpio/consumer.h seem missed.

> +#include <linux/input/mt.h>
> +#include <linux/input/touchscreen.h>
> +#include <linux/regulator/consumer.h>

...

> +enum nt36xxx_fw_state {
> + NT36XXX_STATE_INIT = 0xa0, /* IC reset */
> + NT36XXX_STATE_REK, /* ReK baseline */
> + NT36XXX_STATE_REK_FINISH, /* Baseline is ready */
> + NT36XXX_STATE_NORMAL_RUN, /* Normal run */
> + NT36XXX_STATE_MAX = 0xaf
> +};

Perhaps kernel doc?

...

> +static int nt36xxx_set_page(struct nt36xxx_i2c *ts, u32 pageaddr)
> +{
> + u32 data = cpu_to_be32(pageaddr) >> 8;
> + int ret;
> +
> + ret = regmap_noinc_write(ts->fw_regmap, NT36XXX_CMD_SET_PAGE,
> + &data, sizeof(data));

> + if (ret == 0)
> + usleep_range(100, 200);
> +
> + return ret;

Can you use traditional pattern, i.e.

if (ret)
return ret;

...
return 0;

?

> +}
> +
> +static int nt36xxx_sw_reset_idle(struct nt36xxx_i2c *ts)
> +{
> + int ret;
> +
> + ret = regmap_write(ts->regmap, ts->hw_client->addr,
> + NT36XXX_CMD_SW_RESET);
> +

> + usleep_range(15000, 16000);

Even in error case? Also, can you explain the value of delay?

> + return ret;
> +}
> +
> +static int nt36xxx_bootloader_reset(struct nt36xxx_i2c *ts)
> +{
> + int ret;
> +
> + ret = regmap_write(ts->regmap, ts->hw_client->addr,
> + NT36XXX_CMD_BOOTLOADER_RESET);
> +

> + msleep(35);

Same as above, esp. taking into account quite a long delay.

> + return ret;
> +}
> +
> +static int nt36xxx_check_reset_state(struct nt36xxx_i2c *ts,
> + enum nt36xxx_fw_state fw_state)
> +{
> + u8 buf[2] = { 0 };
> + int ret, retry = NT36XXX_MAX_FW_RST_RETRY;
> +
> + do {
> + ret = regmap_noinc_read(ts->fw_regmap,
> + NT36XXX_EVT_RESET_COMPLETE,
> + buf, sizeof(buf));
> + if (likely(ret == 0) &&
> + (buf[0] >= fw_state) &&
> + (buf[0] <= NT36XXX_STATE_MAX)) {
> + ret = 0;
> + break;
> + }
> + usleep_range(10000, 11000);
> + } while (--retry);
> +
> + if (!retry) {
> + dev_err(&ts->hw_client->dev, "Firmware reset failed.\n");
> + ret = -EBUSY;
> + }

This sounds like it should be a part of regmap API, such as
regmap_read_poll_timeout().

> +
> + return ret;
> +}
> +
> +static int nt36xxx_read_pid(struct nt36xxx_i2c *ts)
> +{
> + u8 buf[2] = { 0 };
> + int ret = 0;

Redundant assignments.

> + ret = nt36xxx_set_page(ts, ts->mmap->evtbuf_addr);
> + if (unlikely(ret < 0))
> + return ret;
> +
> + ret = regmap_noinc_read(ts->fw_regmap, NT36XXX_EVT_PROJECTID,
> + buf, sizeof(buf));
> + if (unlikely(ret < 0))
> + return ret;
> +

> + ts->fw_info.nvt_pid = (buf[1] << 8) + buf[0];

Define buf as __le16 and use le16_to_cpu().

> +
> + return 0;
> +}
> +
> +static int __nt36xxx_get_fw_info(struct nt36xxx_i2c *ts)
> +{
> + struct nt36xxx_fw_info *fwi = &ts->fw_info;
> + u8 buf[11] = { 0 };
> + int ret = 0;
> +
> + ret = nt36xxx_set_page(ts, ts->mmap->evtbuf_addr);
> + if (unlikely(ret < 0))
> + return ret;
> +
> + ret = regmap_noinc_read(ts->fw_regmap, NT36XXX_EVT_FWINFO,
> + buf, sizeof(buf));
> + if (ret)
> + return ret;
> +
> + fwi->fw_ver = buf[0];
> + fwi->x_num = buf[2];
> + fwi->y_num = buf[3];
> + fwi->abs_x_max = (u16)((buf[4] << 8) | buf[5]);
> + fwi->abs_y_max = (u16)((buf[6] << 8) | buf[7]);

be16_to_cpu() or get_unaligned_be16(), though here it's aligned.

> + fwi->max_buttons = buf[10];
> +
> + /* Check fw info integrity and clear x_num, y_num if broken */
> + if ((buf[0] + buf[1]) != 0xFF) {
> + dev_err(&ts->hw_client->dev,
> + "FW info is broken! fw_ver=0x%02X, ~fw_ver=0x%02X\n",
> + buf[0], buf[1]);
> + fwi->fw_ver = 0;
> + fwi->x_num = 18;
> + fwi->y_num = 32;
> + fwi->abs_x_max = TOUCH_DEFAULT_MAX_WIDTH;
> + fwi->abs_y_max = TOUCH_DEFAULT_MAX_HEIGHT;
> + fwi->max_buttons = 0;
> + return -EINVAL;
> + }
> +
> + /* Get Novatek ProjectID */
> + return nt36xxx_read_pid(ts);
> +}

...

> +static int nvt_stop_crc_reboot(struct nt36xxx_i2c *ts)
> +{
> + u8 buf[3] = { 0 };
> + u8 val;
> + int ret, retry = NT36XXX_MAX_RETRIES;
> +
> + /* Read dummy buffer to check CRC fail reboot is happening or not */
> +
> + /* Change I2C index to prevent getting 0xFF, but not 0xFC */
> + ret = nt36xxx_set_page(ts, NT36XXX_PAGE_CHIP_INFO);
> + if (ret) {
> + dev_dbg(&ts->hw_client->dev,
> + "CRC reset failed: Cannot select page.\n");
> + return ret;
> + }
> +
> + /* If ChipID command returns 0xFC or 0xFF, the MCU is in CRC reboot */
> + ret = regmap_noinc_read(ts->fw_regmap, NT36XXX_EVT_CHIPID,
> + buf, sizeof(buf));
> + if (ret)
> + return ret;
> +
> + if (((buf[0] == 0xFC) && (buf[1] == 0xFC) && (buf[2] == 0xFC)) ||
> + ((buf[0] == 0xFF) && (buf[1] == 0xFF) && (buf[2] == 0xFF))) {

You may decrese indentation by switching above to be negative conditional.

> + /* IC is in CRC fail reboot loop, needs to be stopped! */
> + do {
> + /* Special reset-idle sequence for CRC failure */
> + ret = regmap_write(ts->regmap, ts->hw_client->addr,
> + NT36XXX_CMD_SW_RESET);

> + ret += regmap_write(ts->regmap, ts->hw_client->addr,
> + NT36XXX_CMD_SW_RESET);

It's not good practice to sum error codes.

> + if (ret)
> + dev_dbg(&ts->hw_client->dev,
> + "SW Reset failed: may not recover\n");
> + usleep_range(1000, 1100);
> +
> + /* Clear CRC_ERR_FLAG */
> + ret = nt36xxx_set_page(ts, NT36XXX_PAGE_CRC);
> + if (ret)
> + continue;
> +
> + val = 0xA5;
> + ret = regmap_raw_write(ts->fw_regmap, NT36XXX_EVT_CRC,
> + &val, sizeof(val));
> + if (ret)
> + continue;
> +
> + /* Check CRC_ERR_FLAG */
> + ret = nt36xxx_set_page(ts, NT36XXX_PAGE_CRC);
> + if (ret)
> + continue;
> +
> + ret = regmap_noinc_read(ts->fw_regmap, NT36XXX_EVT_CRC,
> + &buf, sizeof(buf));
> + if (ret)
> + continue;
> +
> + if (buf[0] == 0xA5)
> + break;
> + } while (--retry);
> +
> + if (retry == 0) {
> + dev_err(&ts->hw_client->dev,
> + "CRC reset failed: buf=0x%02x%02x\n",
> + buf[0], buf[1]);

%2ph

> + }
> + }
> +
> + return 0;
> +}
> +
> +static int nt36xxx_i2c_chip_version_init(struct nt36xxx_i2c *ts)
> +{
> + u8 buf[7] = { 0 };
> + int retry = NT36XXX_MAX_RETRIES;
> + int sz = sizeof(trim_id_table) / sizeof(struct nt36xxx_trim_table);
> + int i, list, mapid, ret;
> +
> + ret = nt36xxx_bootloader_reset(ts);
> + if (ret < 0) {
> + dev_err(&ts->hw_client->dev, "Can't reset the nvt IC\n");
> + return ret;
> + }
> +
> + do {
> + ret = nt36xxx_sw_reset_idle(ts);
> + if (ret < 0)
> + continue;
> +
> + ret = regmap_write(ts->regmap, ts->hw_client->addr, NT36XXX_CMD_UNLOCK);
> + if (ret)
> + continue;
> + usleep_range(10000, 11000);
> +
> + ret = nt36xxx_set_page(ts, NT36XXX_PAGE_CHIP_INFO);
> + if (ret)
> + continue;
> +
> + memset(buf, 0, ARRAY_SIZE(buf));
> + ret = regmap_noinc_read(ts->fw_regmap, NT36XXX_EVT_CHIPID,
> + buf, sizeof(buf));
> + if (ret)
> + continue;
> +
> + /* Compare read chip id with trim list */
> + for (list = 0; list < sz; list++) {
> + /* Compare each not masked byte */
> + for (i = 0; i < NT36XXX_ID_LEN_MAX; i++) {
> + if (trim_id_table[list].mask[i] &&
> + buf[i] != trim_id_table[list].id[i])
> + break;
> + }
> +
> + if (i == NT36XXX_ID_LEN_MAX) {
> + mapid = trim_id_table[list].mapid;
> + ts->mmap = &nt36xxx_memory_maps[mapid];
> + return 0;
> + }
> +
> + ts->mmap = NULL;
> + ret = -ENOENT;
> + }
> +
> + /* Stop CRC check to prevent IC auto reboot */
> + if (((buf[1] == 0xFC) && (buf[2] == 0xFC) &&
> + (buf[3] == 0xFC)) ||
> + ((buf[1] == 0xFF) && (buf[2] == 0xFF) &&
> + (buf[3] == 0xFF))) {

You already have the same code above. Perhaps helper is good to have for this.

> + ret = nvt_stop_crc_reboot(ts);
> + if (ret < 0)
> + continue;
> + }
> +
> + usleep_range(10000, 11000);
> + } while (--retry);
> +
> + return ret;
> +}
> +
> +static const struct regmap_config nt36xxx_i2c_regmap_hw_config = {
> + .name = "nt36xxx_i2c_hw",
> + .reg_bits = 8,
> + .val_bits = 8,
> + .cache_type = REGCACHE_NONE,
> +};
> +
> +static const struct regmap_config nt36xxx_i2c_regmap_fw_config = {
> + .name = "nt36xxx_i2c_fw",
> + .reg_bits = 8,
> + .val_bits = 8,
> + .cache_type = REGCACHE_NONE,
> +};
> +
> +static void nt36xxx_disable_regulators(void *data)
> +{
> + struct nt36xxx_i2c *ts = data;
> +
> + regulator_bulk_disable(NT36XXX_NUM_SUPPLIES, ts->supplies);
> +}
> +
> +static int nt36xxx_i2c_probe(struct i2c_client *hw_client,
> + const struct i2c_device_id *id)
> +{
> + struct nt36xxx_i2c *ts;
> + struct input_dev *input;
> + int ret;
> +
> + if (!i2c_check_functionality(hw_client->adapter, I2C_FUNC_I2C)) {
> + dev_err(&hw_client->dev, "i2c_check_functionality error\n");
> + return -EIO;
> + }
> +
> + if (!hw_client->irq) {
> + dev_err(&hw_client->dev, "No irq specified\n");
> + return -EINVAL;
> + }
> +
> + ts = devm_kzalloc(&hw_client->dev, sizeof(struct nt36xxx_i2c), GFP_KERNEL);
> + if (!ts)
> + return -ENOMEM;
> +
> + ts->supplies = devm_kcalloc(&hw_client->dev,
> + NT36XXX_NUM_SUPPLIES,
> + sizeof(struct regulator_bulk_data),
> + GFP_KERNEL);
> + if (!ts->supplies)
> + return -ENOMEM;
> +
> + input = devm_input_allocate_device(&hw_client->dev);
> + if (!input)
> + return -ENOMEM;
> +
> + ts->fw_client = i2c_new_dummy_device(hw_client->adapter,
> + NT36XXX_FW_ADDR);
> + if (IS_ERR(ts->fw_client)) {
> + dev_err(&hw_client->dev, "Cannot add FW I2C device\n");
> + return PTR_ERR(ts->fw_client);
> + }
> +
> + ts->hw_client = hw_client;
> + ts->input = input;
> + i2c_set_clientdata(ts->hw_client, ts);
> + i2c_set_clientdata(ts->fw_client, ts);
> +
> + ts->reset_gpio = devm_gpiod_get_optional(&hw_client->dev, "reset",
> + GPIOD_OUT_HIGH);
> + if (IS_ERR(ts->reset_gpio))
> + return PTR_ERR(ts->reset_gpio);

> + if (ts->reset_gpio)

Redundant. If you mark GPIO as optional all those checks should not be here.

> + gpiod_set_consumer_name(ts->reset_gpio, "nt36xxx reset");
> +
> + /* These supplies are optional */
> + ts->supplies[0].supply = "vdd";
> + ts->supplies[1].supply = "vio";
> + ret = devm_regulator_bulk_get(&hw_client->dev,
> + NT36XXX_NUM_SUPPLIES,
> + ts->supplies);
> + if (ret != 0) {

if (ret)

> + if (ret != -EPROBE_DEFER)
> + dev_err(&hw_client->dev,
> + "Cannot get supplies: %d\n", ret);
> + return ret;

I think there is no return dev_err_probe() here b/c Dmitry is against it?

> + }
> +
> + ts->regmap = devm_regmap_init_i2c(ts->hw_client,
> + &nt36xxx_i2c_regmap_hw_config);
> + if (IS_ERR(ts->regmap)) {
> + dev_err(&hw_client->dev, "regmap (hw-addr) init failed\n");
> + return PTR_ERR(ts->regmap);
> + }
> +
> + ts->fw_regmap = devm_regmap_init_i2c(ts->fw_client,
> + &nt36xxx_i2c_regmap_fw_config);
> + if (IS_ERR(ts->fw_regmap)) {
> + dev_err(&hw_client->dev, "regmap (fw-addr) init failed\n");
> + return PTR_ERR(ts->fw_regmap);
> + }
> +
> + ret = regulator_bulk_enable(NT36XXX_NUM_SUPPLIES, ts->supplies);
> + if (ret)
> + return ret;

> + usleep_range(10000, 11000);

Why?

> + ret = devm_add_action_or_reset(&hw_client->dev,
> + nt36xxx_disable_regulators, ts);
> + if (ret)
> + return ret;
> +
> + mutex_init(&ts->lock);
> +
> + /* Set memory maps for the specific chip version */
> + ret = nt36xxx_i2c_chip_version_init(ts);
> + if (ret) {
> + dev_err(&hw_client->dev, "Failed to check chip version\n");
> + return ret;
> + }
> +
> + /* Reset the MCU */
> + ret = nt36xxx_bootloader_reset(ts);

> + if (unlikely(ret < 0))

All these unlikely() calls are unlikely needed. Please, drop them for
the sake of readability.

> + return ret;
> +
> + /* Check and eventually wait until the MCU goes in reset state */
> + ret = nt36xxx_check_reset_state(ts, NT36XXX_STATE_INIT);
> + if (unlikely(ret < 0))
> + return ret;
> +
> + /* Get informations from the TS firmware */
> + ret = nt36xxx_get_fw_info(ts);
> + if (unlikely(ret < 0))
> + return ret;
> +
> + input->phys = devm_kasprintf(&hw_client->dev, GFP_KERNEL,
> + "%s/input0", dev_name(&hw_client->dev));
> +
> + input->name = "Novatek NT36XXX Touchscreen";
> + input->id.bustype = BUS_I2C;
> + input->dev.parent = &hw_client->dev;
> +
> + __set_bit(EV_KEY, input->evbit);
> + __set_bit(EV_ABS, input->evbit);
> + input_set_capability(input, EV_KEY, BTN_TOUCH);
> +
> + ret = input_mt_init_slots(input, TOUCH_MAX_FINGER_NUM,
> + INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
> + if (ret) {
> + dev_err(&hw_client->dev, "Cannot init MT slots (%d)\n", ret);
> + return ret;
> + }
> +
> + input_set_abs_params(input, ABS_MT_PRESSURE, 0,
> + TOUCH_MAX_PRESSURE, 0, 0);
> + input_set_abs_params(input, ABS_MT_TOUCH_MAJOR, 0, 255, 0, 0);
> +
> + input_set_abs_params(input, ABS_MT_POSITION_X, 0,
> + ts->fw_info.abs_x_max - 1, 0, 0);
> + input_set_abs_params(input, ABS_MT_POSITION_Y, 0,
> + ts->fw_info.abs_y_max - 1, 0, 0);
> +
> + /* Override the firmware defaults, if needed */
> + touchscreen_parse_properties(input, true, &ts->prop);
> +
> + input_set_drvdata(input, ts);
> +
> + ret = input_register_device(ts->input);
> + if (ret) {
> + dev_err(&hw_client->dev, "Failed to register input device: %d\n",
> + ret);
> + return ret;
> + }
> +
> + ret = devm_request_threaded_irq(&hw_client->dev, hw_client->irq, NULL,
> + nt36xxx_i2c_irq_handler, IRQF_ONESHOT,
> + hw_client->name, ts);
> + if (ret) {
> + dev_err(&hw_client->dev, "request irq failed: %d\n", ret);

> + return ret;
> + }
> +
> + return 0;

return ret; ?

> +}
> +
> +static int __maybe_unused nt36xxx_i2c_suspend(struct device *dev)
> +{
> + struct nt36xxx_i2c *ts = i2c_get_clientdata(to_i2c_client(dev));
> + int ret;
> +
> + disable_irq(ts->hw_client->irq);
> +
> + ret = regmap_write(ts->fw_regmap, NT36XXX_EVT_HOST_CMD,
> + NT36XXX_CMD_ENTER_SLEEP);
> + if (unlikely(ret)) {
> + dev_err(&ts->hw_client->dev, "Cannot enter suspend!!\n");
> + return ret;
> + }

> + if (ts->reset_gpio)

Redundant.

> + gpiod_set_value(ts->reset_gpio, 1);
> +
> + return 0;
> +}
> +
> +static int __maybe_unused nt36xxx_i2c_resume(struct device *dev)
> +{
> + struct nt36xxx_i2c *ts = i2c_get_clientdata(to_i2c_client(dev));
> + int ret;
> +
> + mutex_lock(&ts->lock);

> + if (ts->reset_gpio)

Redundant.

> + gpiod_set_value(ts->reset_gpio, 0);

> + /* Reboot the MCU (also recalibrates the TS) */
> + ret = nt36xxx_bootloader_reset(ts);
> + if (ret < 0)
> + goto end;
> +
> + ret = nt36xxx_check_reset_state(ts, NT36XXX_STATE_REK);
> + if (ret < 0)
> + goto end;
> +
> + enable_irq(ts->hw_client->irq);
> +end:
> + mutex_unlock(&ts->lock);
> + return ret;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(nt36xxx_i2c_pm,
> + nt36xxx_i2c_suspend, nt36xxx_i2c_resume);
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id nt36xxx_of_match[] = {
> + { .compatible = "novatek,nt36525" },
> + { }
> +};
> +MODULE_DEVICE_TABLE(of, nt36xxx_of_match);
> +#endif
> +
> +static const struct i2c_device_id nt36xxx_i2c_ts_id[] = {
> + { "NVT-ts", 0 },
> + { }
> +};
> +MODULE_DEVICE_TABLE(i2c, nt36xxx_i2c_ts_id);
> +
> +static struct i2c_driver nt36xxx_i2c_ts_driver = {
> + .driver = {
> + .name = "nt36xxx_ts",
> + .pm = &nt36xxx_i2c_pm,

> + .of_match_table = of_match_ptr(nt36xxx_of_match),

You may do a good job by dropping these of_match_ptr() along with ugly
ifdeffery above. It will allow to use it on ACPI-enabled platforms.

> + },

--
With Best Regards,
Andy Shevchenko

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