| Message ID | 20161202141146.31281-2-lee.jones@linaro.org |
|---|---|
| State | New |
| Headers | show |
Hi Lee On 12/02/2016 03:11 PM, Lee Jones wrote: > Until this point, it has not been possible for serial applications > to toggle the UART RTS line. This can be useful with certain > configurations. For example, when using a Mezzanine on a Linaro > 96board, RTS line is used to take the the on-board microcontroller typo "the the on" > in and out of reset. > > Signed-off-by: Lee Jones <lee.jones@linaro.org> > --- > drivers/tty/serial/st-asc.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c > index 379e5bd..ce46898 100644 > --- a/drivers/tty/serial/st-asc.c > +++ b/drivers/tty/serial/st-asc.c > @@ -30,6 +30,7 @@ > #include <linux/of_platform.h> > #include <linux/serial_core.h> > #include <linux/clk.h> > +#include <linux/gpio/consumer.h> > > #define DRIVER_NAME "st-asc" > #define ASC_SERIAL_NAME "ttyAS" > @@ -38,6 +39,7 @@ > > struct asc_port { > struct uart_port port; > + struct gpio_desc *rts; > struct clk *clk; > unsigned int hw_flow_control:1; > unsigned int force_m1:1; > @@ -381,12 +383,16 @@ static unsigned int asc_tx_empty(struct uart_port *port) > > static void asc_set_mctrl(struct uart_port *port, unsigned int mctrl) > { > + struct asc_port *ascport = to_asc_port(port); > + > /* > * This routine is used for seting signals of: DTR, DCD, CTS/RTS > * We use ASC's hardware for CTS/RTS, so don't need any for that. > * Some boards have DTR and DCD implemented using PIO pins, > * code to do this should be hooked in here. > */ > + > + gpiod_set_value(ascport->rts, mctrl & TIOCM_RTS); > } > > static unsigned int asc_get_mctrl(struct uart_port *port) > @@ -731,12 +737,20 @@ MODULE_DEVICE_TABLE(of, asc_match); > static int asc_serial_probe(struct platform_device *pdev) > { > int ret; > + struct device_node *np = pdev->dev.of_node; > struct asc_port *ascport; > + struct gpio_desc *gpiod; > > ascport = asc_of_get_asc_port(pdev); > if (!ascport) > return -ENODEV; > > + gpiod = devm_get_gpiod_from_child(&pdev->dev, "rts", &np->fwnode); > + if (!IS_ERR(gpiod)) { > + gpiod_direction_output(gpiod, 0); > + ascport->rts = gpiod; > + } > + > ret = asc_init_port(ascport, pdev); > if (ret) > return ret; >
On Tue, 06 Dec 2016, Peter Griffin wrote: > On Mon, 05 Dec 2016, Patrice Chotard wrote: > > On 12/02/2016 03:11 PM, Lee Jones wrote: > > > Until this point, it has not been possible for serial applications > > > to toggle the UART RTS line. This can be useful with certain > > > configurations. For example, when using a Mezzanine on a Linaro > > > 96board, RTS line is used to take the the on-board microcontroller > > > > typo "the the on" > > > > > in and out of reset. > > > > > > Signed-off-by: Lee Jones <lee.jones@linaro.org> > > > --- > > > drivers/tty/serial/st-asc.c | 14 ++++++++++++++ > > > 1 file changed, 14 insertions(+) > > > > > > diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c > > > index 379e5bd..ce46898 100644 > > > --- a/drivers/tty/serial/st-asc.c > > > +++ b/drivers/tty/serial/st-asc.c > > > @@ -30,6 +30,7 @@ > > > #include <linux/of_platform.h> > > > #include <linux/serial_core.h> > > > #include <linux/clk.h> > > > +#include <linux/gpio/consumer.h> > > > > > > #define DRIVER_NAME "st-asc" > > > #define ASC_SERIAL_NAME "ttyAS" > > > @@ -38,6 +39,7 @@ > > > > > > struct asc_port { > > > struct uart_port port; > > > + struct gpio_desc *rts; > > > struct clk *clk; > > > unsigned int hw_flow_control:1; > > > unsigned int force_m1:1; > > > @@ -381,12 +383,16 @@ static unsigned int asc_tx_empty(struct uart_port *port) > > > > > > static void asc_set_mctrl(struct uart_port *port, unsigned int mctrl) > > > { > > > + struct asc_port *ascport = to_asc_port(port); > > > + > > > /* > > > * This routine is used for seting signals of: DTR, DCD, CTS/RTS > > > * We use ASC's hardware for CTS/RTS, so don't need any for that. > > > * Some boards have DTR and DCD implemented using PIO pins, > > > * code to do this should be hooked in here. > > > */ > > > + > > > + gpiod_set_value(ascport->rts, mctrl & TIOCM_RTS); > > This now puts the code and the comment above out of sync with each > other. > > However just checking the stih410 datasheet and I don't think this patch > to control RTS via a GPIO is required anyway. > > The correct way of handling this is to add UART10_RTS and UART10_CTS pins > to the pinctrl_serial0 group so they are properly configured for their cts/rts > alternate function. Once the pins are correctly configured, the IP block should > control the signals correctly like the comment says. That was the first thing I tried. It didn't work. -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog
On Tue, 06 Dec 2016, Lee Jones wrote: > On Tue, 06 Dec 2016, Peter Griffin wrote: > > On Mon, 05 Dec 2016, Patrice Chotard wrote: > > > On 12/02/2016 03:11 PM, Lee Jones wrote: > > > > Until this point, it has not been possible for serial applications > > > > to toggle the UART RTS line. This can be useful with certain > > > > configurations. For example, when using a Mezzanine on a Linaro > > > > 96board, RTS line is used to take the the on-board microcontroller > > > > > > typo "the the on" > > > > > > > in and out of reset. > > > > > > > > Signed-off-by: Lee Jones <lee.jones@linaro.org> > > > > --- > > > > drivers/tty/serial/st-asc.c | 14 ++++++++++++++ > > > > 1 file changed, 14 insertions(+) > > > > > > > > diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c > > > > index 379e5bd..ce46898 100644 > > > > --- a/drivers/tty/serial/st-asc.c > > > > +++ b/drivers/tty/serial/st-asc.c > > > > @@ -30,6 +30,7 @@ > > > > #include <linux/of_platform.h> > > > > #include <linux/serial_core.h> > > > > #include <linux/clk.h> > > > > +#include <linux/gpio/consumer.h> > > > > > > > > #define DRIVER_NAME "st-asc" > > > > #define ASC_SERIAL_NAME "ttyAS" > > > > @@ -38,6 +39,7 @@ > > > > > > > > struct asc_port { > > > > struct uart_port port; > > > > + struct gpio_desc *rts; > > > > struct clk *clk; > > > > unsigned int hw_flow_control:1; > > > > unsigned int force_m1:1; > > > > @@ -381,12 +383,16 @@ static unsigned int asc_tx_empty(struct uart_port *port) > > > > > > > > static void asc_set_mctrl(struct uart_port *port, unsigned int mctrl) > > > > { > > > > + struct asc_port *ascport = to_asc_port(port); > > > > + > > > > /* > > > > * This routine is used for seting signals of: DTR, DCD, CTS/RTS > > > > * We use ASC's hardware for CTS/RTS, so don't need any for that. > > > > * Some boards have DTR and DCD implemented using PIO pins, > > > > * code to do this should be hooked in here. > > > > */ > > > > + > > > > + gpiod_set_value(ascport->rts, mctrl & TIOCM_RTS); > > > > This now puts the code and the comment above out of sync with each > > other. > > > > However just checking the stih410 datasheet and I don't think this patch > > to control RTS via a GPIO is required anyway. > > > > The correct way of handling this is to add UART10_RTS and UART10_CTS pins > > to the pinctrl_serial0 group so they are properly configured for their cts/rts > > alternate function. Once the pins are correctly configured, the IP block should > > control the signals correctly like the comment says. > > That was the first thing I tried. It didn't work. cts = <&pio17 2 ALT1 IN>; rts = <&pio17 3 ALT1 OUT>; -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog
diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c index 379e5bd..ce46898 100644 --- a/drivers/tty/serial/st-asc.c +++ b/drivers/tty/serial/st-asc.c @@ -30,6 +30,7 @@ #include <linux/of_platform.h> #include <linux/serial_core.h> #include <linux/clk.h> +#include <linux/gpio/consumer.h> #define DRIVER_NAME "st-asc" #define ASC_SERIAL_NAME "ttyAS" @@ -38,6 +39,7 @@ struct asc_port { struct uart_port port; + struct gpio_desc *rts; struct clk *clk; unsigned int hw_flow_control:1; unsigned int force_m1:1; @@ -381,12 +383,16 @@ static unsigned int asc_tx_empty(struct uart_port *port) static void asc_set_mctrl(struct uart_port *port, unsigned int mctrl) { + struct asc_port *ascport = to_asc_port(port); + /* * This routine is used for seting signals of: DTR, DCD, CTS/RTS * We use ASC's hardware for CTS/RTS, so don't need any for that. * Some boards have DTR and DCD implemented using PIO pins, * code to do this should be hooked in here. */ + + gpiod_set_value(ascport->rts, mctrl & TIOCM_RTS); } static unsigned int asc_get_mctrl(struct uart_port *port) @@ -731,12 +737,20 @@ MODULE_DEVICE_TABLE(of, asc_match); static int asc_serial_probe(struct platform_device *pdev) { int ret; + struct device_node *np = pdev->dev.of_node; struct asc_port *ascport; + struct gpio_desc *gpiod; ascport = asc_of_get_asc_port(pdev); if (!ascport) return -ENODEV; + gpiod = devm_get_gpiod_from_child(&pdev->dev, "rts", &np->fwnode); + if (!IS_ERR(gpiod)) { + gpiod_direction_output(gpiod, 0); + ascport->rts = gpiod; + } + ret = asc_init_port(ascport, pdev); if (ret) return ret;
Until this point, it has not been possible for serial applications to toggle the UART RTS line. This can be useful with certain configurations. For example, when using a Mezzanine on a Linaro 96board, RTS line is used to take the the on-board microcontroller in and out of reset. Signed-off-by: Lee Jones <lee.jones@linaro.org> --- drivers/tty/serial/st-asc.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) -- 2.10.2