Commit bba61f50 authored by Hans de Goede's avatar Hans de Goede Committed by Wolfram Sang
Browse files

i2c: mv64xxx: The n clockdiv factor is 0 based on sunxi SoCs 



According to the datasheets the n factor for dividing the tclk is
2 to the power n on Allwinner SoCs, not 2 to the power n + 1 as it is
on other mv64xxx implementations.

I've contacted Allwinner about this and they have confirmed that the
datasheet is correct.

This commit fixes the clk-divider calculations for Allwinner SoCs
accordingly.

Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
Acked-by: default avatarMaxime Ripard <maxime.ripard@free-electrons.com>
Tested-by: default avatarOlliver Schinagl <oliver@schinagl.nl>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org
parent 9abd29e7

drivers/i2c/busses/i2c-mv64xxx.c

+18 −9
Original line number Diff line number Diff line
@@ -146,6 +146,8 @@ struct mv64xxx_i2c_data { 
	bool			errata_delay;

	struct reset_control	*rstc;

	bool			irq_clear_inverted;

	/* Clk div is 2 to the power n, not 2 to the power n + 1 */

	bool			clk_n_base_0;

};



static struct mv64xxx_i2c_regs mv64xxx_i2c_regs_mv64xxx = {
@@ -757,25 +759,29 @@ MODULE_DEVICE_TABLE(of, mv64xxx_i2c_of_match_table); 
#ifdef CONFIG_OF

#ifdef CONFIG_HAVE_CLK

static int

mv64xxx_calc_freq(const int tclk, const int n, const int m)

mv64xxx_calc_freq(struct mv64xxx_i2c_data *drv_data,

		  const int tclk, const int n, const int m)

{

	if (drv_data->clk_n_base_0)

		return tclk / (10 * (m + 1) * (1 << n));

	else

		return tclk / (10 * (m + 1) * (2 << n));

}



static bool

mv64xxx_find_baud_factors(const u32 req_freq, const u32 tclk, u32 *best_n,

			  u32 *best_m)

mv64xxx_find_baud_factors(struct mv64xxx_i2c_data *drv_data,

			  const u32 req_freq, const u32 tclk)

{

	int freq, delta, best_delta = INT_MAX;

	int m, n;



	for (n = 0; n <= 7; n++)

		for (m = 0; m <= 15; m++) {

			freq = mv64xxx_calc_freq(tclk, n, m);

			freq = mv64xxx_calc_freq(drv_data, tclk, n, m);

			delta = req_freq - freq;

			if (delta >= 0 && delta < best_delta) {

				*best_m = m;

				*best_n = n;

				drv_data->freq_m = m;

				drv_data->freq_n = n;

				best_delta = delta;

			}

			if (best_delta == 0)
@@ -813,8 +819,11 @@ mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data, 
	if (of_property_read_u32(np, "clock-frequency", &bus_freq))

		bus_freq = 100000; /* 100kHz by default */



	if (!mv64xxx_find_baud_factors(bus_freq, tclk,

				       &drv_data->freq_n, &drv_data->freq_m)) {

	if (of_device_is_compatible(np, "allwinner,sun4i-a10-i2c") ||

	    of_device_is_compatible(np, "allwinner,sun6i-a31-i2c"))

		drv_data->clk_n_base_0 = true;



	if (!mv64xxx_find_baud_factors(drv_data, bus_freq, tclk)) {

		rc = -EINVAL;

		goto out;

	}

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