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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: Hans de Goede <hdegoede@redhat.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Tested-by: Olliver Schinagl <oliver@schinagl.nl>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org
This commit is contained in:
Hans de Goede 2015-09-27 16:57:08 +02:00 committed by Wolfram Sang
parent 9abd29e7c1
commit bba61f50f7
1 changed files with 18 additions and 9 deletions
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27
drivers/i2c/busses/i2c-mv64xxx.c
View File

@ -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)
{
return tclk / (10 * (m + 1) * (2 << n));
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;
}