From bba61f50f76574ca5b84b310925be7c2e8e64275 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Sun, 27 Sep 2015 16:57:08 +0200 Subject: 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 Acked-by: Maxime Ripard Tested-by: Olliver Schinagl Signed-off-by: Wolfram Sang Cc: stable@kernel.org --- drivers/i2c/busses/i2c-mv64xxx.c | 27 ++++++++++++++++++--------- 1 file changed, 18 insertions(+), 9 deletions(-) (limited to 'drivers/i2c') diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c index 5801227b97ab..43207f52e5a3 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 = { @@ -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; } -- cgit v1.2.3-55-g7522