diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-omap.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-omap.c | 39 |
1 files changed, 30 insertions, 9 deletions
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c index ece0125a1ee..c73475dd0fb 100644 --- a/drivers/i2c/busses/i2c-omap.c +++ b/drivers/i2c/busses/i2c-omap.c @@ -333,8 +333,18 @@ static int omap_i2c_init(struct omap_i2c_dev *dev) if (cpu_is_omap2430() || cpu_is_omap34xx()) { - /* HSI2C controller internal clk rate should be 19.2 Mhz */ - internal_clk = 19200; + /* + * HSI2C controller internal clk rate should be 19.2 Mhz for + * HS and for all modes on 2430. On 34xx we can use lower rate + * to get longer filter period for better noise suppression. + * The filter is iclk (fclk for HS) period. + */ + if (dev->speed > 400 || cpu_is_omap_2430()) + internal_clk = 19200; + else if (dev->speed > 100) + internal_clk = 9600; + else + internal_clk = 4000; fclk_rate = clk_get_rate(dev->fclk) / 1000; /* Compute prescaler divisor */ @@ -343,17 +353,28 @@ static int omap_i2c_init(struct omap_i2c_dev *dev) /* If configured for High Speed */ if (dev->speed > 400) { + unsigned long scl; + /* For first phase of HS mode */ - fsscll = internal_clk / (400 * 2) - 6; - fssclh = internal_clk / (400 * 2) - 6; + scl = internal_clk / 400; + fsscll = scl - (scl / 3) - 7; + fssclh = (scl / 3) - 5; /* For second phase of HS mode */ - hsscll = fclk_rate / (dev->speed * 2) - 6; - hssclh = fclk_rate / (dev->speed * 2) - 6; + scl = fclk_rate / dev->speed; + hsscll = scl - (scl / 3) - 7; + hssclh = (scl / 3) - 5; + } else if (dev->speed > 100) { + unsigned long scl; + + /* Fast mode */ + scl = internal_clk / dev->speed; + fsscll = scl - (scl / 3) - 7; + fssclh = (scl / 3) - 5; } else { - /* To handle F/S modes */ - fsscll = internal_clk / (dev->speed * 2) - 6; - fssclh = internal_clk / (dev->speed * 2) - 6; + /* Standard mode */ + fsscll = internal_clk / (dev->speed * 2) - 7; + fssclh = internal_clk / (dev->speed * 2) - 5; } scll = (hsscll << OMAP_I2C_SCLL_HSSCLL) | fsscll; sclh = (hssclh << OMAP_I2C_SCLH_HSSCLH) | fssclh; |