static int i2c_dw_set_timings_master()

in busses/i2c-designware-master.c [40:165]

• 102 lines of code
• 15 McCabe index (conditional complexity)

static int i2c_dw_set_timings_master(struct dw_i2c_dev *dev)
{
	u32 comp_param1;
	u32 sda_falling_time, scl_falling_time;
	struct i2c_timings *t = &dev->timings;
	const char *fp_str = "";
	u32 ic_clk;
	int ret;

	ret = i2c_dw_acquire_lock(dev);
	if (ret)
		return ret;

	ret = regmap_read(dev->map, DW_IC_COMP_PARAM_1, &comp_param1);
	i2c_dw_release_lock(dev);
	if (ret)
		return ret;

	/* Set standard and fast speed dividers for high/low periods */
	sda_falling_time = t->sda_fall_ns ?: 300; /* ns */
	scl_falling_time = t->scl_fall_ns ?: 300; /* ns */

	/* Calculate SCL timing parameters for standard mode if not set */
	if (!dev->ss_hcnt || !dev->ss_lcnt) {
		ic_clk = i2c_dw_clk_rate(dev);
		dev->ss_hcnt =
			i2c_dw_scl_hcnt(ic_clk,
					4000,	/* tHD;STA = tHIGH = 4.0 us */
					sda_falling_time,
					0,	/* 0: DW default, 1: Ideal */
					0);	/* No offset */
		dev->ss_lcnt =
			i2c_dw_scl_lcnt(ic_clk,
					4700,	/* tLOW = 4.7 us */
					scl_falling_time,
					0);	/* No offset */
	}
	dev_dbg(dev->dev, "Standard Mode HCNT:LCNT = %d:%d\n",
		dev->ss_hcnt, dev->ss_lcnt);

	/*
	 * Set SCL timing parameters for fast mode or fast mode plus. Only
	 * difference is the timing parameter values since the registers are
	 * the same.
	 */
	if (t->bus_freq_hz == I2C_MAX_FAST_MODE_PLUS_FREQ) {
		/*
		 * Check are Fast Mode Plus parameters available. Calculate
		 * SCL timing parameters for Fast Mode Plus if not set.
		 */
		if (dev->fp_hcnt && dev->fp_lcnt) {
			dev->fs_hcnt = dev->fp_hcnt;
			dev->fs_lcnt = dev->fp_lcnt;
		} else {
			ic_clk = i2c_dw_clk_rate(dev);
			dev->fs_hcnt =
				i2c_dw_scl_hcnt(ic_clk,
						260,	/* tHIGH = 260 ns */
						sda_falling_time,
						0,	/* DW default */
						0);	/* No offset */
			dev->fs_lcnt =
				i2c_dw_scl_lcnt(ic_clk,
						500,	/* tLOW = 500 ns */
						scl_falling_time,
						0);	/* No offset */
		}
		fp_str = " Plus";
	}
	/*
	 * Calculate SCL timing parameters for fast mode if not set. They are
	 * needed also in high speed mode.
	 */
	if (!dev->fs_hcnt || !dev->fs_lcnt) {
		ic_clk = i2c_dw_clk_rate(dev);
		dev->fs_hcnt =
			i2c_dw_scl_hcnt(ic_clk,
					600,	/* tHD;STA = tHIGH = 0.6 us */
					sda_falling_time,
					0,	/* 0: DW default, 1: Ideal */
					0);	/* No offset */
		dev->fs_lcnt =
			i2c_dw_scl_lcnt(ic_clk,
					1300,	/* tLOW = 1.3 us */
					scl_falling_time,
					0);	/* No offset */
	}
	dev_dbg(dev->dev, "Fast Mode%s HCNT:LCNT = %d:%d\n",
		fp_str, dev->fs_hcnt, dev->fs_lcnt);

	/* Check is high speed possible and fall back to fast mode if not */
	if ((dev->master_cfg & DW_IC_CON_SPEED_MASK) ==
		DW_IC_CON_SPEED_HIGH) {
		if ((comp_param1 & DW_IC_COMP_PARAM_1_SPEED_MODE_MASK)
			!= DW_IC_COMP_PARAM_1_SPEED_MODE_HIGH) {
			dev_err(dev->dev, "High Speed not supported!\n");
			t->bus_freq_hz = I2C_MAX_FAST_MODE_FREQ;
			dev->master_cfg &= ~DW_IC_CON_SPEED_MASK;
			dev->master_cfg |= DW_IC_CON_SPEED_FAST;
			dev->hs_hcnt = 0;
			dev->hs_lcnt = 0;
		} else if (!dev->hs_hcnt || !dev->hs_lcnt) {
			ic_clk = i2c_dw_clk_rate(dev);
			dev->hs_hcnt =
				i2c_dw_scl_hcnt(ic_clk,
						160,	/* tHIGH = 160 ns */
						sda_falling_time,
						0,	/* DW default */
						0);	/* No offset */
			dev->hs_lcnt =
				i2c_dw_scl_lcnt(ic_clk,
						320,	/* tLOW = 320 ns */
						scl_falling_time,
						0);	/* No offset */
		}
		dev_dbg(dev->dev, "High Speed Mode HCNT:LCNT = %d:%d\n",
			dev->hs_hcnt, dev->hs_lcnt);
	}

	ret = i2c_dw_set_sda_hold(dev);
	if (ret)
		return ret;

	dev_dbg(dev->dev, "Bus speed: %s\n", i2c_freq_mode_string(t->bus_freq_hz));
	return 0;
}