+ if (adap->hwadapnr == 0)
+ return (struct mxs_i2c_regs *)MXS_I2C0_BASE;
+ else
+ return (struct mxs_i2c_regs *)MXS_I2C1_BASE;
+}
+
+static unsigned int mxs_i2c_get_bus_speed(struct i2c_adapter *adap)
+{
+ struct mxs_i2c_regs *i2c_regs = mxs_i2c_get_base(adap);
+ uint32_t clk = mxc_get_clock(MXC_XTAL_CLK);
+ uint32_t timing0;
+
+ timing0 = readl(&i2c_regs->hw_i2c_timing0);
+ /*
+ * This is a reverse version of the algorithm presented in
+ * i2c_set_bus_speed(). Please refer there for details.
+ */
+ return clk / ((((timing0 >> 16) - 3) * 2) + 38);
+}
+
+static uint mxs_i2c_set_bus_speed(struct i2c_adapter *adap, uint speed)
+{
+ struct mxs_i2c_regs *i2c_regs = mxs_i2c_get_base(adap);
+ /*
+ * The timing derivation algorithm. There is no documentation for this
+ * algorithm available, it was derived by using the scope and fiddling
+ * with constants until the result observed on the scope was good enough
+ * for 20kHz, 50kHz, 100kHz, 200kHz, 300kHz and 400kHz. It should be
+ * possible to assume the algorithm works for other frequencies as well.
+ *
+ * Note it was necessary to cap the frequency on both ends as it's not
+ * possible to configure completely arbitrary frequency for the I2C bus
+ * clock.
+ */
+ uint32_t clk = mxc_get_clock(MXC_XTAL_CLK);
+ uint32_t base = ((clk / speed) - 38) / 2;
+ uint16_t high_count = base + 3;
+ uint16_t low_count = base - 3;
+ uint16_t rcv_count = (high_count * 3) / 4;
+ uint16_t xmit_count = low_count / 4;
+
+ if (speed > 540000) {
+ printf("MXS I2C: Speed too high (%d Hz)\n", speed);
+ return -EINVAL;
+ }
+
+ if (speed < 12000) {
+ printf("MXS I2C: Speed too low (%d Hz)\n", speed);
+ return -EINVAL;
+ }
+
+ writel((high_count << 16) | rcv_count, &i2c_regs->hw_i2c_timing0);
+ writel((low_count << 16) | xmit_count, &i2c_regs->hw_i2c_timing1);
+
+ writel((0x0030 << I2C_TIMING2_BUS_FREE_OFFSET) |
+ (0x0030 << I2C_TIMING2_LEADIN_COUNT_OFFSET),
+ &i2c_regs->hw_i2c_timing2);
+
+ return 0;
+}
+
+static void mxs_i2c_reset(struct i2c_adapter *adap)
+{
+ struct mxs_i2c_regs *i2c_regs = mxs_i2c_get_base(adap);