@@ -14,6 +14,12 @@ Optional properties :
- i2c-sda-hold-time-ns : should contain the SDA hold time in nanoseconds.
This option is only supported in hardware blocks version 1.11a or newer.
+ - i2c-scl-falling-time : should contain the SCL falling time in nanoseconds.
+ This value which is by default 300ns is used to compute the tLOW period.
+
+ - i2c-sda-falling-time : should contain the SDA falling time in nanoseconds.
+ This value which is by default 300ns is used to compute the tHIGH period.
+
Example :
i2c@f0000 {
@@ -34,4 +40,6 @@ Example :
interrupts = <12 1>;
clock-frequency = <400000>;
i2c-sda-hold-time-ns = <300>;
+ i2c-sda-falling-time-ns = <300>;
+ i2c-scl-falling-time-ns = <300>;
};
@@ -219,7 +219,7 @@ i2c_dw_scl_hcnt(u32 ic_clk, u32 tSYMBOL, u32 tf, int cond, int offset)
*
* If your hardware is free from tHD;STA issue, try this one.
*/
- return (ic_clk * tSYMBOL + 5000) / 10000 - 8 + offset;
+ return (ic_clk * tSYMBOL + 500000) / 1000000 - 8 + offset;
else
/*
* Conditional expression:
@@ -235,7 +235,8 @@ i2c_dw_scl_hcnt(u32 ic_clk, u32 tSYMBOL, u32 tf, int cond, int offset)
* The reason why we need to take into account "tf" here,
* is the same as described in i2c_dw_scl_lcnt().
*/
- return (ic_clk * (tSYMBOL + tf) + 5000) / 10000 - 3 + offset;
+ return (ic_clk * (tSYMBOL + tf) + 500000) / 1000000
+ - 3 + offset;
}
static u32 i2c_dw_scl_lcnt(u32 ic_clk, u32 tLOW, u32 tf, int offset)
@@ -251,7 +252,7 @@ static u32 i2c_dw_scl_lcnt(u32 ic_clk, u32 tLOW, u32 tf, int offset)
* account the fall time of SCL signal (tf). Default tf value
* should be 0.3 us, for safety.
*/
- return ((ic_clk * (tLOW + tf) + 5000) / 10000) - 1 + offset;
+ return ((ic_clk * (tLOW + tf) + 500000) / 1000000) - 1 + offset;
}
static void __i2c_dw_enable(struct dw_i2c_dev *dev, bool enable)
@@ -288,6 +289,7 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
u32 input_clock_khz;
u32 hcnt, lcnt;
u32 reg;
+ u32 sda_falling_time, scl_falling_time;
input_clock_khz = dev->get_clk_rate_khz(dev);
@@ -309,15 +311,18 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
/* set standard and fast speed deviders for high/low periods */
+ sda_falling_time = dev->sda_falling_time ?: 300; /* ns */
+ scl_falling_time = dev->scl_falling_time ?: 300; /* ns */
+
/* Standard-mode */
hcnt = i2c_dw_scl_hcnt(input_clock_khz,
- 40, /* tHD;STA = tHIGH = 4.0 us */
- 3, /* tf = 0.3 us */
+ 4000, /* tHD;STA = tHIGH = 4.0 us */
+ sda_falling_time,
0, /* 0: DW default, 1: Ideal */
0); /* No offset */
lcnt = i2c_dw_scl_lcnt(input_clock_khz,
- 47, /* tLOW = 4.7 us */
- 3, /* tf = 0.3 us */
+ 4700, /* tLOW = 4.7 us */
+ scl_falling_time,
0); /* No offset */
/* Allow platforms to specify the ideal HCNT and LCNT values */
@@ -331,13 +336,13 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
/* Fast-mode */
hcnt = i2c_dw_scl_hcnt(input_clock_khz,
- 6, /* tHD;STA = tHIGH = 0.6 us */
- 3, /* tf = 0.3 us */
+ 600, /* tHD;STA = tHIGH = 0.6 us */
+ sda_falling_time,
0, /* 0: DW default, 1: Ideal */
0); /* No offset */
lcnt = i2c_dw_scl_lcnt(input_clock_khz,
- 13, /* tLOW = 1.3 us */
- 3, /* tf = 0.3 us */
+ 1300, /* tLOW = 1.3 us */
+ scl_falling_time,
0); /* No offset */
if (dev->fs_hcnt && dev->fs_lcnt) {
@@ -99,6 +99,8 @@ struct dw_i2c_dev {
unsigned int rx_fifo_depth;
int rx_outstanding;
u32 sda_hold_time;
+ u32 sda_falling_time;
+ u32 scl_falling_time;
u16 ss_hcnt;
u16 ss_lcnt;
u16 fs_hcnt;
@@ -159,6 +159,13 @@ static int dw_i2c_probe(struct platform_device *pdev)
"i2c-sda-hold-time-ns", &ht);
dev->sda_hold_time = div_u64((u64)ic_clk * ht + 500000,
1000000);
+
+ of_property_read_u32(pdev->dev.of_node,
+ "i2c-sda-falling-time-ns",
+ &dev->sda_falling_time);
+ of_property_read_u32(pdev->dev.of_node,
+ "i2c-scl-falling-time-ns",
+ &dev->scl_falling_time);
}
dev->functionality =