static int siox_gpio_pushpull()

in siox-bus-gpio.c [28:85]

• 37 lines of code
• 6 McCabe index (conditional complexity)

static int siox_gpio_pushpull(struct siox_master *smaster,
			      size_t setbuf_len, const u8 setbuf[],
			      size_t getbuf_len, u8 getbuf[])
{
	struct siox_gpio_ddata *ddata = siox_master_get_devdata(smaster);
	size_t i;
	size_t cycles = max(setbuf_len, getbuf_len);

	/* reset data and clock */
	gpiod_set_value_cansleep(ddata->dout, 0);
	gpiod_set_value_cansleep(ddata->dclk, 0);

	gpiod_set_value_cansleep(ddata->dld, 1);
	ndelay(siox_loadhigh_ns);
	gpiod_set_value_cansleep(ddata->dld, 0);

	for (i = 0; i < cycles; ++i) {
		u8 set = 0, get = 0;
		size_t j;

		if (i >= cycles - setbuf_len)
			set = setbuf[i - (cycles - setbuf_len)];

		for (j = 0; j < 8; ++j) {
			get <<= 1;
			if (gpiod_get_value_cansleep(ddata->din))
				get |= 1;

			/* DOUT is logically inverted */
			gpiod_set_value_cansleep(ddata->dout, !(set & 0x80));
			set <<= 1;

			gpiod_set_value_cansleep(ddata->dclk, 1);
			ndelay(siox_clkhigh_ns);
			gpiod_set_value_cansleep(ddata->dclk, 0);
		}

		if (i < getbuf_len)
			getbuf[i] = get;

		ndelay(siox_bytegap_ns);
	}

	gpiod_set_value_cansleep(ddata->dld, 1);
	ndelay(siox_loadhigh_ns);
	gpiod_set_value_cansleep(ddata->dld, 0);

	/*
	 * Resetting dout isn't necessary protocol wise, but it makes the
	 * signals more pretty because the dout level is deterministic between
	 * cycles. Note that this only affects dout between the master and the
	 * first siox device. dout for the later devices depend on the output of
	 * the previous siox device.
	 */
	gpiod_set_value_cansleep(ddata->dout, 0);

	return 0;
}