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i2c-bfin-twi: fix CLKDIV calculation

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Calculation of the CLKDIV speed setting should be done using base 10 math
rather than base 2.  We also avoid exceeding the spec due to integer
truncation and a 50% duty cycle.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
This commit is contained in:
Sonic Zhang 2009-12-21 09:28:30 -05:00 committed by Ben Dooks
parent c9f937e4a3
commit ac07fb4dc1
1 changed files with 3 additions and 3 deletions
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6
drivers/i2c/busses/i2c-bfin-twi.c
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@ -693,13 +693,13 @@ static int i2c_bfin_twi_probe(struct platform_device *pdev)
}
/* Set TWI internal clock as 10MHz */
write_CONTROL(iface, ((get_sclk() / 1024 / 1024 + 5) / 10) & 0x7F);
write_CONTROL(iface, ((get_sclk() / 1000 / 1000 + 5) / 10) & 0x7F);
/*
* We will not end up with a CLKDIV=0 because no one will specify
* 20kHz SCL or less in Kconfig now. (5 * 1024 / 20 = 0x100)
* 20kHz SCL or less in Kconfig now. (5 * 1000 / 20 = 250)
*/
clkhilow = 5 * 1024 / CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ;
clkhilow = ((10 * 1000 / CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ) + 1) / 2;
/* Set Twi interface clock as specified */
write_CLKDIV(iface, (clkhilow << 8) | clkhilow);