diff options
| -rw-r--r-- | drivers/i2c/busses/i2c-designware-common.c | 5 | ||||
| -rw-r--r-- | drivers/i2c/busses/i2c-designware-core.h | 6 | ||||
| -rw-r--r-- | drivers/i2c/busses/i2c-designware-master.c | 23 |
3 files changed, 32 insertions, 2 deletions
diff --git a/drivers/i2c/busses/i2c-designware-common.c b/drivers/i2c/busses/i2c-designware-common.c index 443f946acf36..857783d458fb 100644 --- a/drivers/i2c/busses/i2c-designware-common.c +++ b/drivers/i2c/busses/i2c-designware-common.c @@ -382,6 +382,11 @@ int i2c_dw_fw_parse_and_configure(struct dw_i2c_dev *dev) i2c_parse_fw_timings(device, t, false); + if (device_property_read_u32(device, "snps,bus-capacitance-pf", &dev->bus_capacitance_pF)) + dev->bus_capacitance_pF = 100; + + dev->clk_freq_optimized = device_property_read_bool(device, "snps,clk-freq-optimized"); + i2c_dw_adjust_bus_speed(dev); if (is_of_node(fwnode)) diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h index 520f9699e3bd..347843b4f5dd 100644 --- a/drivers/i2c/busses/i2c-designware-core.h +++ b/drivers/i2c/busses/i2c-designware-core.h @@ -242,6 +242,10 @@ struct reset_control; * @set_sda_hold_time: callback to retrieve IP specific SDA hold timing * @mode: operation mode - DW_IC_MASTER or DW_IC_SLAVE * @rinfo: I²C GPIO recovery information + * @bus_capacitance_pF: bus capacitance in picofarads + * @clk_freq_optimized: if this value is true, it means the hardware reduces + * its internal clock frequency by reducing the internal latency required + * to generate the high period and low period of SCL line. * * HCNT and LCNT parameters can be used if the platform knows more accurate * values than the one computed based only on the input clock frequency. @@ -299,6 +303,8 @@ struct dw_i2c_dev { int (*set_sda_hold_time)(struct dw_i2c_dev *dev); int mode; struct i2c_bus_recovery_info rinfo; + u32 bus_capacitance_pF; + bool clk_freq_optimized; }; #define ACCESS_INTR_MASK BIT(0) diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c index 528b969253a7..eca8998d640f 100644 --- a/drivers/i2c/busses/i2c-designware-master.c +++ b/drivers/i2c/busses/i2c-designware-master.c @@ -151,19 +151,38 @@ static int i2c_dw_set_timings_master(struct dw_i2c_dev *dev) dev->hs_hcnt = 0; dev->hs_lcnt = 0; } else if (!dev->hs_hcnt || !dev->hs_lcnt) { + u32 t_high, t_low; + + /* + * The legal values stated in the databook for bus + * capacitance are only 100pF and 400pF. + * If dev->bus_capacitance_pF is greater than or equals + * to 400, t_high and t_low are assumed to be + * appropriate values for 400pF, otherwise 100pF. + */ + if (dev->bus_capacitance_pF >= 400) { + /* assume bus capacitance is 400pF */ + t_high = dev->clk_freq_optimized ? 160 : 120; + t_low = 320; + } else { + /* assume bus capacitance is 100pF */ + t_high = 60; + t_low = dev->clk_freq_optimized ? 120 : 160; + } + ic_clk = i2c_dw_clk_rate(dev); dev->hs_hcnt = i2c_dw_scl_hcnt(dev, DW_IC_HS_SCL_HCNT, ic_clk, - 160, /* tHIGH = 160 ns */ + t_high, sda_falling_time, 0); /* No offset */ dev->hs_lcnt = i2c_dw_scl_lcnt(dev, DW_IC_HS_SCL_LCNT, ic_clk, - 320, /* tLOW = 320 ns */ + t_low, scl_falling_time, 0); /* No offset */ } |