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Diffstat (limited to 'drivers/i2c/busses/i2c-nomadik.c')
-rw-r--r--drivers/i2c/busses/i2c-nomadik.c40
1 files changed, 28 insertions, 12 deletions
diff --git a/drivers/i2c/busses/i2c-nomadik.c b/drivers/i2c/busses/i2c-nomadik.c
index 8bf9ac01301a..51e61d8127cb 100644
--- a/drivers/i2c/busses/i2c-nomadik.c
+++ b/drivers/i2c/busses/i2c-nomadik.c
@@ -340,6 +340,8 @@ static void setup_i2c_controller(struct nmk_i2c_dev *dev)
{
u32 brcr1, brcr2;
u32 i2c_clk, div;
+ u32 ns;
+ u16 slsu;
writel(0x0, dev->virtbase + I2C_CR);
writel(0x0, dev->virtbase + I2C_HSMCR);
@@ -347,18 +349,38 @@ static void setup_i2c_controller(struct nmk_i2c_dev *dev)
writel(0x0, dev->virtbase + I2C_RFTR);
writel(0x0, dev->virtbase + I2C_DMAR);
+ i2c_clk = clk_get_rate(dev->clk);
+
/*
* set the slsu:
*
* slsu defines the data setup time after SCL clock
- * stretching in terms of i2c clk cycles. The
- * needed setup time for the three modes are 250ns,
- * 100ns, 10ns respectively thus leading to the values
- * of 14, 6, 2 for a 48 MHz i2c clk.
+ * stretching in terms of i2c clk cycles + 1 (zero means
+ * "wait one cycle"), the needed setup time for the three
+ * modes are 250ns, 100ns, 10ns respectively.
+ *
+ * As the time for one cycle T in nanoseconds is
+ * T = (1/f) * 1000000000 =>
+ * slsu = cycles / (1000000000 / f) + 1
*/
- writel(dev->cfg.slsu << 16, dev->virtbase + I2C_SCR);
+ ns = DIV_ROUND_UP_ULL(1000000000ULL, i2c_clk);
+ switch (dev->cfg.sm) {
+ case I2C_FREQ_MODE_FAST:
+ case I2C_FREQ_MODE_FAST_PLUS:
+ slsu = DIV_ROUND_UP(100, ns); /* Fast */
+ break;
+ case I2C_FREQ_MODE_HIGH_SPEED:
+ slsu = DIV_ROUND_UP(10, ns); /* High */
+ break;
+ case I2C_FREQ_MODE_STANDARD:
+ default:
+ slsu = DIV_ROUND_UP(250, ns); /* Standard */
+ break;
+ }
+ slsu += 1;
- i2c_clk = clk_get_rate(dev->clk);
+ dev_dbg(&dev->adev->dev, "calculated SLSU = %04x\n", slsu);
+ writel(slsu << 16, dev->virtbase + I2C_SCR);
/*
* The spec says, in case of std. mode the divider is
@@ -915,11 +937,6 @@ static const struct i2c_algorithm nmk_i2c_algo = {
};
static struct nmk_i2c_controller u8500_i2c = {
- /*
- * Slave data setup time; 250ns, 100ns, and 10ns, which
- * is 14, 6 and 2 respectively for a 48Mhz i2c clock.
- */
- .slsu = 0xe,
.tft = 1, /* Tx FIFO threshold */
.rft = 8, /* Rx FIFO threshold */
.clk_freq = 400000, /* fast mode operation */
@@ -1027,7 +1044,6 @@ static int nmk_i2c_probe(struct amba_device *adev, const struct amba_id *id)
/* fetch the controller configuration from machine */
dev->cfg.clk_freq = pdata->clk_freq;
- dev->cfg.slsu = pdata->slsu;
dev->cfg.tft = pdata->tft;
dev->cfg.rft = pdata->rft;
dev->cfg.sm = pdata->sm;