On 12.06.19 11:16, Andy Shevchenko wrote:
On Wed, Jun 12, 2019 at 10:13:05AM +0200, Stefan Roese wrote:
On 11.06.19 16:48, Andy Shevchenko wrote:
On Tue, Jun 11, 2019 at 04:02:54PM +0200, Stefan Roese wrote:
On 11.06.19 14:44, Andy Shevchenko wrote:
On Tue, Jun 11, 2019 at 12:56:03PM +0200, Stefan Roese wrote:
static inline void serial8250_out_MCR(struct uart_8250_port *up, int value)
{
serial_out(up, UART_MCR, value);
+
+ if (up->gpios) {
+ int mctrl_gpio = 0;
+
+ if (value & UART_MCR_RTS)
+ mctrl_gpio |= TIOCM_RTS;
+ if (value & UART_MCR_DTR)
+ mctrl_gpio |= TIOCM_DTR;
+
+ mctrl_gpio_set(up->gpios, mctrl_gpio);
+ }
}
static inline int serial8250_in_MCR(struct uart_8250_port *up)
{
- return serial_in(up, UART_MCR);
+ int mctrl;
+
+ mctrl = serial_in(up, UART_MCR);
+
+ if (up->gpios) {
+ int mctrl_gpio = 0;
+
+ /* save current MCR values */
+ if (mctrl & UART_MCR_RTS)
+ mctrl_gpio |= TIOCM_RTS;
+ if (mctrl & UART_MCR_DTR)
+ mctrl_gpio |= TIOCM_DTR;
+
+ mctrl_gpio = mctrl_gpio_get_outputs(up->gpios, &mctrl_gpio);
+ if (mctrl_gpio & TIOCM_RTS)
+ mctrl |= UART_MCR_RTS;
+ else
+ mctrl &= ~UART_MCR_RTS;
+
+ if (mctrl_gpio & TIOCM_DTR)
+ mctrl |= UART_MCR_DTR;
+ else
+ mctrl &= ~UART_MCR_DTR;
+ }
+
+ return mctrl;
}
These are using OR logic with potentially volatile data. Shouldn't we mask
unused bits in UART_MCR in case of up->gpios != NULL?
Sorry, I don't see, which bits you are referring to? Could you please be
a bit more specific with the variable / macro meant (example)?
I meant that we double write values in the out() which might have some
consequences, though I hope nothing wrong with it happens.
Where is the double write to a register? Sorry, I fail to spot it.
Not to the one register. From the functional point of view the same signal is
set up twice: once per UART register, once per GPIO pins.
In the in() we read the all bits in the register.
As now I look at the implementation of mctrl_gpio_get_outputs(),
I think we rather get helpers for conversion between TIOCM and UART_MCR values,
so, they can be used in get_mctrl() / set_mctrl() and above.
Do you something like this in mind?
More likely
static inline int serial8250_MCR_to_TIOCM(int mcr)
MSR_to_TIOCM (see below) ...
{
int tiocm = 0;
if (mcr & ...)
tiocm |= ...;
...
return tiocm;
}
static inline int serial8250_TIOCM_to_MCR(int tiocm)
{
... in a similar way ...
}
While implementing such wrapper functions I noticed, that get_mctrl() /
set_mctrl() need TIOCM->MCR and MSR->TIOCM (notice MSR vs MCR here) but
serial8250_in_MCR() needs MCR->TIOCM. So there is not that much
overlay here. Additionally the wrappers would need to handle all bits
and only some of them are needed in serial8250_in/out_MCR(), so I would
need to add masking here as well.
For my taste its not really worth adding these wrappers as they won't
make things much clearer (if at all).
Thanks,
Stefan
