i2c: rk3x: Move spec timing data to "static const" structs (b58fd3be) · Commits · 戴 / test

drivers/i2c/busses/i2c-rk3x.c

+55 −28

Original line number	Diff line number	Diff line
		@@ -75,6 +75,34 @@ enum {
		#define WAIT_TIMEOUT 1000 /* ms */
		#define DEFAULT_SCL_RATE (100 * 1000) /* Hz */

		/**
		* struct i2c_spec_values:
		* @min_low_ns: min LOW period of the SCL clock
		* @min_high_ns: min HIGH period of the SCL cloc
		* @min_setup_start_ns: min set-up time for a repeated START conditio
		* @max_data_hold_ns: max data hold time
		*/
		struct i2c_spec_values {
		unsigned long min_low_ns;
		unsigned long min_high_ns;
		unsigned long min_setup_start_ns;
		unsigned long max_data_hold_ns;
		};

		static const struct i2c_spec_values standard_mode_spec = {
		.min_low_ns = 4700,
		.min_high_ns = 4000,
		.min_setup_start_ns = 4700,
		.max_data_hold_ns = 3450,
		};

		static const struct i2c_spec_values fast_mode_spec = {
		.min_low_ns = 1300,
		.min_high_ns = 600,
		.min_setup_start_ns = 600,
		.max_data_hold_ns = 900,
		};

		/**
		* struct rk3x_i2c_calced_timings:
		* @div_low: Divider output for low
		@@ -459,6 +487,21 @@ out:
		return IRQ_HANDLED;
		}

		/**
		* Get timing values of I2C specification
		*
		* @speed: Desired SCL frequency
		*
		* Returns: Matched i2c spec values.
		*/
		static const struct i2c_spec_values *rk3x_i2c_get_spec(unsigned int speed)
		{
		if (speed <= 100000)
		return &standard_mode_spec;
		else
		return &fast_mode_spec;
		}

		/**
		* Calculate divider values for desired SCL frequency
		*
		@@ -474,10 +517,6 @@ static int rk3x_i2c_calc_divs(unsigned long clk_rate,
		struct i2c_timings *t,
		struct rk3x_i2c_calced_timings *t_calc)
		{
		unsigned long spec_min_low_ns, spec_min_high_ns;
		unsigned long spec_setup_start, spec_max_data_hold_ns;
		unsigned long data_hold_buffer_ns;

		unsigned long min_low_ns, min_high_ns;
		unsigned long max_low_ns, min_total_ns;

		@@ -489,6 +528,8 @@ static int rk3x_i2c_calc_divs(unsigned long clk_rate,
		unsigned long min_div_for_hold, min_total_div;
		unsigned long extra_div, extra_low_div, ideal_low_div;

		unsigned long data_hold_buffer_ns = 50;
		const struct i2c_spec_values *spec;
		int ret = 0;

		/* Only support standard-mode and fast-mode */
		@@ -511,22 +552,8 @@ static int rk3x_i2c_calc_divs(unsigned long clk_rate,
		* This is because the i2c host on Rockchip holds the data line
		* for half the low time.
		*/
		if (t->bus_freq_hz <= 100000) {
		/* Standard-mode */
		spec_min_low_ns = 4700;
		spec_setup_start = 4700;
		spec_min_high_ns = 4000;
		spec_max_data_hold_ns = 3450;
		data_hold_buffer_ns = 50;
		} else {
		/* Fast-mode */
		spec_min_low_ns = 1300;
		spec_setup_start = 600;
		spec_min_high_ns = 600;
		spec_max_data_hold_ns = 900;
		data_hold_buffer_ns = 50;
		}
		min_high_ns = t->scl_rise_ns + spec_min_high_ns;
		spec = rk3x_i2c_get_spec(t->bus_freq_hz);
		min_high_ns = t->scl_rise_ns + spec->min_high_ns;

		/*
		* Timings for repeated start:
		@@ -536,14 +563,14 @@ static int rk3x_i2c_calc_divs(unsigned long clk_rate,
		* We need to account for those rules in picking our "high" time so
		* we meet tSU;STA and tHD;STA times.
		*/
		min_high_ns = max(min_high_ns,
		DIV_ROUND_UP((t->scl_rise_ns + spec_setup_start) * 1000, 875));
		min_high_ns = max(min_high_ns,
		DIV_ROUND_UP((t->scl_rise_ns + spec_setup_start +
		t->sda_fall_ns + spec_min_high_ns), 2));

		min_low_ns = t->scl_fall_ns + spec_min_low_ns;
		max_low_ns = spec_max_data_hold_ns * 2 - data_hold_buffer_ns;
		min_high_ns = max(min_high_ns, DIV_ROUND_UP(
		(t->scl_rise_ns + spec->min_setup_start_ns) * 1000, 875));
		min_high_ns = max(min_high_ns, DIV_ROUND_UP(
		(t->scl_rise_ns + spec->min_setup_start_ns + t->sda_fall_ns +
		spec->min_high_ns), 2));

		min_low_ns = t->scl_fall_ns + spec->min_low_ns;
		max_low_ns = spec->max_data_hold_ns * 2 - data_hold_buffer_ns;
		min_total_ns = min_low_ns + min_high_ns;

		/* Adjust to avoid overflow */

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