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rk3288: guarantee i2c low period more than 1.3us 

change i2c clock low period and high period proportion to 7:3
guarantee the low period more than 1.3us

BUG=None
TEST=Boot on veyron_pinky rev2,check the i2c clock frequency

Original-Change-Id: I235e9e3ff54ab3b9cabad36bab58a8409f7005a0
Original-Signed-off-by: huang lin <hl@rock-chips.com>
Original-Reviewed-on: https://chromium-review.googlesource.com/223002
Original-Reviewed-by: Julius Werner <jwerner@chromium.org>

(cherry picked from commit 57a5d90d394086483e0dcdd6279678658d07d842)
Signed-off-by: Aaron Durbin <adurbin@chromium.org>

Change-Id: I6b0c9dfa540354f6463ed90c9f3f9503a4d5749e
Reviewed-on: http://review.coreboot.org/9259
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
This commit is contained in:
huang lin 2014-10-10 23:26:21 -07:00 committed by Aaron Durbin
parent 45e16fc199
commit 8affee5897
1 changed files with 4 additions and 4 deletions
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8
src/soc/rockchip/rk3288/i2c.c
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@ -284,7 +284,7 @@ void i2c_init(unsigned int bus, unsigned int hz)
unsigned int clk_div; unsigned int clk_div;
unsigned int divl; unsigned int divl;
unsigned int divh; unsigned int divh;
unsigned int i2c_src_clk; unsigned int i2c_src_clk = 0;
struct rk3288_i2c_regs *regs = i2c_bus[bus]; struct rk3288_i2c_regs *regs = i2c_bus[bus];
/*i2c0,i2c2 src clk from pd_bus_pclk /*i2c0,i2c2 src clk from pd_bus_pclk
@ -308,9 +308,9 @@ void i2c_init(unsigned int bus, unsigned int hz)
/*SCL Divisor = 8*(CLKDIVL + 1 + CLKDIVH + 1) /*SCL Divisor = 8*(CLKDIVL + 1 + CLKDIVH + 1)
SCL = PCLK/ SCLK Divisor SCL = PCLK/ SCLK Divisor
*/ */
clk_div = div_round_up(i2c_src_clk, hz * 8) - 2; clk_div = div_round_up(i2c_src_clk, hz * 8);
divh = clk_div / 2; divh = clk_div * 3 / 7 - 1;
divl = ALIGN_UP(clk_div, 2) / 2; divl = clk_div - divh - 2;
assert((divh < 65536) && (divl < 65536)); assert((divh < 65536) && (divl < 65536));
writel((divh << 16) | (divl << 0), &regs->i2c_clkdiv); writel((divh << 16) | (divl << 0), &regs->i2c_clkdiv);
} }