About NXP SC16IS741A(I2C to UART) with Jetson TX1

Autonomous Machines Jetson & Embedded Systems Jetson TX1
1

Dear Sir,

We would like to use NXP SC16IS741A(I2C to UART) to get the additional UART interface.

L4T:28.2.0
CONFIG_SERIAL_SC16IS7XX=y
CONFIG_SERIAL_SC16IS7XX_I2C=y
Driver Path: /kernel/kernel-4.4/drivers/tty/serial/sc16is7xx.c

This is my final device tree setting

	i2c@7000c000 {
		sc16is741: sc16is741@48 {
		        status = "okay";
                compatible = "nxp,sc16is741";
                reg = <0x48>;
                interrupt-parent = <&gpio>;
                interrupts = <TEGRA_GPIO(K, 4) IRQ_TYPE_EDGE_FALLING>; 
                #interrupt-cells = <2>;
			    interrupt-controller;
                gpio-controller;
                #gpio-cells = <2>;
                vcc-supply = <&battery_reg>;
        };
	};

After booting,

[ 0.503552] <0> [sk]sc16is7xx_i2c_probe irq=0x91: check 0x91
[ 0.503714] sc16is7xx: probe of 0-0048 failed with error -2

=> I got a error at the probe stage.

After debuging,

static int sc16is7xx_probe(struct device *dev,
			   const struct sc16is7xx_devtype *devtype,
			   struct regmap *regmap, int irq, unsigned long flags)
{
	struct sched_param sched_param = { .sched_priority = MAX_RT_PRIO / 2 };
	unsigned long freq, *pfreq = dev_get_platdata(dev);
	int i, ret;
	struct sc16is7xx_port *s;
printk("<0> [sk]sc16is7xx_i2c_probe irq=0x%x: check 0x%x\n", irq, gpio_to_irq(84) );
	if (IS_ERR(regmap))
		return PTR_ERR(regmap);
printk("<0> [sk] regmap ok\n" );
	/* Alloc port structure */
	s = devm_kzalloc(dev, sizeof(*s) +
			 sizeof(struct sc16is7xx_one) * devtype->nr_uart,
			 GFP_KERNEL);
	if (!s) {
		dev_err(dev, "Error allocating port structure\n");
		return -ENOMEM;
	}

static int sc16is7xx_i2c_probe(struct i2c_client *i2c,
			       const struct i2c_device_id *id)
{
	const struct sc16is7xx_devtype *devtype;
	unsigned long flags = 0;
	struct regmap *regmap;

......

	regcfg.max_register = (0xf << SC16IS7XX_REG_SHIFT) |
			      (devtype->nr_uart - 1);
	regmap = devm_regmap_init_i2c(i2c, &regcfg);

	return sc16is7xx_probe(&i2c->dev, devtype, regmap, i2c->irq, flags);
}

=> The error is from

	if (IS_ERR(regmap))
              return PTR_ERR(regmap);

When I use the i2cdetect command, I can see the hardware at 0x48 address of I2C bus 0.

Can you help me this issue for regmap? or Any suggestion?

3

You may need to trace down the devm_regmap_init_i2c(i2c, &regcfg) to clarify.

4

Hi ShaneCCC,

Can I ask you some questions?

  1. Does it need to config the device tree for the regmap framework?
  2. Do you know how to check the regmap framework ready?

(PS: Sorry about that. I’m not the expert in the regmap.)
Thanks.
S.K.

5

As my experience for the driver need configure it not in the device tree like the sensor driver.

static int ov5693_probe(struct i2c_client *client,
                        const struct i2c_device_id *id)
{
         tc_dev->dev = dev;
        strncpy(tc_dev->name, "ov5693", sizeof(tc_dev->name));
        tc_dev->dev_regmap_config = &ov5693_regmap_config;
        tc_dev->sensor_ops = &ov5693_common_ops;