Hey Hans,
On 27-09-15 16:57, Hans de Goede wrote:
According to the datasheets to 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.
Ah!
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.
So this explains why all my i2c frequenties are double of what I setup.
Thanks for taking the time of figuring it out! I'll give it a test
hopefully soon.
Olliver
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
drivers/i2c/busses/i2c-mv64xxx.c | 27 ++++++++++++++++++---------
1 file changed, 18 insertions(+), 9 deletions(-)
diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
index 30059c1..e75cf6d 100644
--- a/drivers/i2c/busses/i2c-mv64xxx.c
+++ b/drivers/i2c/busses/i2c-mv64xxx.c
@@ -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 = {
@@ -759,25 +761,29 @@ 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)
@@ -815,8 +821,11 @@ 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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