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path: root/drivers/i2c/busses/i2c-omap.c
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Diffstat (limited to 'drivers/i2c/busses/i2c-omap.c')
-rw-r--r--drivers/i2c/busses/i2c-omap.c39
1 files changed, 30 insertions, 9 deletions
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index ece0125a1ee5..c73475dd0fba 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;