[U-Boot] [PATCH] i2c: designware: Get clock rate from clock DM

[Ley Foon Tan]

On Thu, May 30, 2019 at 5:13 PM Marek Vasut <marex at denx.de> wrote:
>
> On 5/30/19 11:07 AM, Ley Foon Tan wrote:
> > On Thu, May 30, 2019 at 4:59 PM Marek Vasut <marex at denx.de> wrote:
> >>
> >> On 5/30/19 10:43 AM, Ley Foon Tan wrote:
> >>> Get clock rate from clock DM if CONFIG_CLK is enabled.
> >>> Otherwise, uses IC_CLK define.
> >>>
> >>> Signed-off-by: Ley Foon Tan <ley.foon.tan at intel.com>
> >>> ---
> >>>  drivers/i2c/designware_i2c.c | 54 +++++++++++++++++++++++++++++-------
> >>>  1 file changed, 44 insertions(+), 10 deletions(-)
> >>>
> >>> diff --git a/drivers/i2c/designware_i2c.c b/drivers/i2c/designware_i2c.c
> >>> index 9ccc2411a6..a1ed30650c 100644
> >>> --- a/drivers/i2c/designware_i2c.c
> >>> +++ b/drivers/i2c/designware_i2c.c
> >>> @@ -4,6 +4,7 @@
> >>>   * Vipin Kumar, ST Micoelectronics, vipin.kumar at st.com.
> >>>   */
> >>>
> >>> +#include <clk.h>
> >>>  #include <common.h>
> >>>  #include <dm.h>
> >>>  #include <i2c.h>
> >>> @@ -35,6 +36,9 @@ struct dw_i2c {
> >>>       struct i2c_regs *regs;
> >>>       struct dw_scl_sda_cfg *scl_sda_cfg;
> >>>       struct reset_ctl_bulk resets;
> >>> +#if CONFIG_IS_ENABLED(CLK)
> >>> +     struct clk clk;
> >>> +#endif
> >>>  };
> >>>
> >>>  #ifdef CONFIG_SYS_I2C_DW_ENABLE_STATUS_UNSUPPORTED
> >>> @@ -78,7 +82,7 @@ static int dw_i2c_enable(struct i2c_regs *i2c_base, bool enable)
> >>>   */
> >>>  static unsigned int __dw_i2c_set_bus_speed(struct i2c_regs *i2c_base,
> >>>                                          struct dw_scl_sda_cfg *scl_sda_cfg,
> >>> -                                        unsigned int speed)
> >>> +                                        unsigned int speed, u32 bus_mhz)
> >>
> >> unsigned int bus_mhz , it's not a fixed-width register content, but just
> >> some random unsigned integer.
> > You mean change u32 to unsigned int?
>
> Yes
Okay.

>
> >> [...]
> >>
> >>> @@ -523,8 +527,20 @@ static int designware_i2c_xfer(struct udevice *bus, struct i2c_msg *msg,
> >>>  static int designware_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
> >>>  {
> >>>       struct dw_i2c *i2c = dev_get_priv(bus);
> >>> +     ulong rate;
> >>> +
> >>> +#if CONFIG_IS_ENABLED(CLK)
> >>> +     rate = clk_get_rate(&i2c->clk);
> >>
> >> Do we need to re-read the bus frequency for each transfer ?
> >> I would expect set_bus_speed callback to set the frequencies once and
> >> then keep them that way until it's called again.
> > Yes, we can get clock rate when request clock in _probe(). Then keep a
> > copy for future use.
>
> Not in .probe() , in set_bus_speed().
My patch is doing it in designware_i2c_set_bus_speed() already.  We
can't get clock rate in __dw_i2c_set_bus_speed(), because this
function doesn't have struct udevice.


Regards
Ley Foon